Platts Steel Glossary

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Age hardening
Agglomeration

This is when solid particles stick to one another, and while this is an undesirable feature in many powder and particle processing operations, it is essential for the successful sintering of iron ore fines, coke and fluxes into a suitable blast furnace feed.

Alloy steel 

Firstly, what is an alloy? This is a material comprising two or more elements, at least one of them a metal. Alloys achieve better specific characteristics than their constituent parts, and steel is itself an alloy of iron.

Alloy steels are steels in which additional elements have been added to the usual iron, carbon, manganese and silicon that is present in ordinary carbon steels in order to improve their properties and performance. This typically involves better strength and/or hardness and/or ductility and/or corrosion resistance. Several additional elements may be present, and sometimes the desired properties are achieved through a combination of alloying and heat treatment.

There is a vast array of alloy steels developed for very specific applications – such as bearings, gears, shafts, drills, saws, bolts, tyrecord, car bodies, aircraft undercarriages, armour, etc, etc. Alloying elements include bismuth, boron, calcium, chromium, cobalt, lead, nickel, molybdenum, selenium, silicon, sulphur, tellurium, tungsten and vanadium.

 

Alloy surcharge
Aluminized sheet

This is sheet steel to which a thin, hot-dip, aluminium-silicon alloy coating has been applied.

It is primarily used in applications that must withstand or reflect heat and resist corrosion at temperatures that are higher than galvanized coatings can cope with.

The silicon content is usually 5-11% and this promotes adherence of the coating to the substrate. Although most aluminized coatings are applied to cold rolled carbon steel, they are also used on some ferritic stainless steels in order to give car exhausts life-of-vehicle durability.

Aluminized steel is very formable, and typical applications are vehicle exhaust pipes, ovens, furnaces, heat exchangers and bakeware.

The coating is said to be particularly good at resisting salt spray and exhaust condensate corrosion.

Annealing

Annealing is the heating of metal to restore desirable properties after rolling, forging etc. Its function is to soften the metal, relieve internal stresses or improve internal structure. In steel the process is mostly used on cold rolled products – predominantly sheet, but also wire.

However, long products (which are mainly hot rolled to final dimension) are sometimes annealed to meet the onward processing requirements of the customer, eg. cutting, forming, bending, forging.

When steel is cold rolled it can become brittle and difficult to work; austenitic stainless is particularly prone to this. The material is heated to a temperature that allows the internal grain structure to regroup (recrystallise), is held at that temperature, and then cooled.

 

Anti-dumping and countervailing duties

Anti-dumping duties on imports are sought by a trade group or producer(s) in a country or trading bloc. They do so when the goods are believed to be being sold at significantly below their home market price – or even below their cost of production – and as a result cause, or threaten, significant economic injury (material injury) to domestic producers of similar goods.

Countervailing duties on imports are sought when the supplying country’s production and/or exports are directly or indirectly subsidised to the extent that they cause or threaten material injury to domestic producers of these goods.

Both duties are allowed under WTO rules, but are only imposed after an investigation which may reject them.

The US market is attractive to steel exporters most of the time, and this has meant that over the years these duties have been a noticeable feature of that country’s steel trade. But AD and CV duties are also used elsewhere, including by the EU, Canada, Mexico, Southeast Asian countries etc.

 

AOD Process

AOD stands for argon oxygen decarburisation, a refining process associated with the production of stainless steel.

Most stainless steel is initially produced in an electric arc furnace before being transferred to a separate ladle furnace for refining to achieve the precise metallurgical content required – a process known as secondary metallurgy or secondary refining.

In the AOD process, a mixture of argon and oxygen is blown through the molten steel in the ladle furnace, and the oxygen achieves the main objective of oxidising unwanted carbon in the steel melt. But because the vital and expensive chromium contained in all stainless steels is also prone to oxidation and subsequent loss with the process slag, the argon is introduced to inhibit this reaction.

Apparent consumption

This is a statistically-derived figure for national or regional steel consumption during a given period. It is based on the sum of reported mill shipments of finished steel plus steel imports into the country/region, minus steel exports.

While a useful indicator, it does not necessarily accurately reflect real steel demand. This is because stock building or stock depletion in the supply chain (by distributors and/or steel users) can result in apparent consumption either exaggerating or under estimating true steel demand.

Arbitrage

Arbitrage is where a trader, broker or individual sees and exploits small variations in commodity prices, or currency conversion rates or the value of other financial instruments in different markets. The profit comes from buying at one price in one market and then immediately selling the same commodity in a different market for a higher price.


With currencies, traders will take advantage of small differences in conversion rates. Currency exchange rates will also play a part in commodity arbitrage, but the scope for arbitrage is reduced where commodity exchanges in different countries use a common currency (such as the US dollar).


Because the variations in values in different markets are usually quite small, it is necessary to engage in a large volume of transactions, at low transaction cost, to achieve any significant gain. Consequently, arbitrage tends mainly to be the province of trading companies rather than of individual speculators.

Assay

A chemical test performed on a mineral sample to determine the concentration of valuable metal contained.

Austempering

This is a form of heat treatment commonly used on medium-to-high carbon steels and ductile cast iron as it produces a structure that is stronger, tougher and more resistant to shock than those produced with conventional heat treatments. It also results in less distortion to the metal than treatment via quench and tempering.
Compared with conventional quench and tempering, austempering involves keeping the workpiece at the quenching temperature for a longer period of time.

Austenitic steel
Automatic gauge control (AGC)

Apart from correct metallurgy, the key parameters that determine the physical acceptability of flat rolled steel to the customer are its uniformity of thickness, its flatness, and its surface finish.

Automatic gauge control is a combination of hardware and software technology that is fitted to rolling mills to achieve good uniformity of thickness across the width of the sheet and throughout its length. Apart from the separation of mill work rolls, other factors with a bearing on achieving good thickness tolerances are mill speed and strip tension.

Using a combination of computerised thickness sensors and hydraulic mill actuators, the distance between work rolls is continuously adjusted to achieve the desired thickness of a strip of steel that can be passing through the mill at speeds of more than 80km/h.

Back-up rolls

In a rolling mill, back-up rolls exert force on the two rolls which are actually in contact with the metal being processed (the work rolls). The back-up rolls prevent the work rolls from bending under the forces exerted on them as they "squeeze" the metal passing through the mill into a new profile.

Carbon steel and non-ferrous rolling mills are usually 4-high (2 work rolls + 2 back-ups), or 6-high. But in the case of stainless steel, because of the very high forces involved during cold rolling, there is a whole cluster of back-up rolls around the (quite small diameter) work rolls – hence the name "cluster mill" (as an alternative to Sendzimir mill, which is widely used to describe this design).

Backwardation
Baghouse

A term for the dust capture system used in steelworks and foundries. Such installations usually comprise a dust separation and filtering arrangement involving an array of cloth filter bags, and are a very efficient way of preventing the emission of particles to the environment.

Bake hardening

The steel sheet used for automotive bodywork needs to be very formable during the press shop stage of panel manufacture, but must have high strength for optimum in-service performance. These are conflicting requirements which bake hardening resolves by altering the properties of the sheet on the car production line.

Once body panels have been pressed they are painted and the paint is then cured by passing through an oven. The steel has already been work hardened during pressing, but it is during curing, at temperatures of around 170 degrees C for a specific time, that the arrangement of the atoms in the steel changes (in a way known as strain ageing). The result is that after baking and cooling the steel has a higher strength than it did after pressing.

The method is mostly associated with outer automotive body panels which require good dent resistance.

Baled scrap

Baling is a method of compressing assorted scrap into dense cubes which are easily handled and transported. Balers are static units, and are particularly popular for handling lighter types of scrap.

Bankable feasibility study

See feasibility study

Banking
Bars

Long steel products of various different cross-sectional shapes including round, square, L-shaped (angle bars) and tees.

Basic oxygen furnace

See BOF.

Beams

Structural steel products of various shapes used to construct the supporting elements of buildings, bridges, etc. (see also: wide flange beams)

Benchmarking

A technique whereby the best practices and/or achievements in the most successful companies or organisations are used by others in the same sector to measure their own performance and to identify areas and means of improving their procedures or processes in order to achieve similar results.

As it applies to pricing, a benchmark price is one which is agreed between a prominent seller(s) and buyer(s) which is then used by others operating in the same market as a reference for their own pricing.

Premiums or discounts may be applied to the benchmark  price to account for any variations from the reference product.

Beneficiation
Bessemer Process

The Bessemer Process was invented and patented in 1855 by Henry Bessemer. This was the first inexpensive industrial process to make steel from molten pig iron. Although the process had been used outside Europe for hundreds of years before this, this was the first time it was used on an industrial scale.

The main principle of the process is using oxidation to remove impurities from the molten iron by blowing air through the iron. The oxidation of the iron raises the temperature to keep it molten during the operation.

A large container called the Bessemer Converter is used. This is made from steel with a special lining of silica and clay or dolomite.

Bill of lading

This is a document used in seaborne trading to indicate the ownership, quantity, condition and destination of goods, and to act as a receipt for them.

A bill of lading (B/L) is issued by the carrier (ship’s master or ship owner’s office) to the owner or person organising the movement of the goods (the shipper), and provides proof that they have been loaded.

The value of a B/L as a statement of condition is more debatable, for the reality and economics of loading a vessel may make it impractical for a carrier to verify the precise condition of every item of cargo – if for no other reason than packaging may prevent this.

However, if on arrival the quantity and/or condition of the goods is not as stated on the B/L, it is the carrier who is liable for any discrepancy, even though the bill may have been prepared by the shipper.

Normally the recipient of the goods has to show the B/L to take delivery at the destination.

Billet

These are long, continuously cast semis of less than 150mm square/round section. Like blooms they are cut-to-length after casting, and are reheated for rolling.

Billet is the starting point for rolling products like rebar, plain bar, merchant bar and light sections, narrow strip and wire rod. It is also used for seamless tube making.

Where ingot casting is employed, blooms are the starting point for rolling billet.

Black pipe

This is an uncoated steel tubular product and is called black because of the dark coloured iron-oxide scale formed on the surface of the steel.
This pipe is strong and is used in the oil and petroleum industries, for water transfer systems, for high pressure steam and air supplies, for commercial hot water systems and sometimes for protecting electrical wiring.

Blackplate

This is thin, low carbon, cold reduced steel coil which is used as a substrate for producing tinplate or tin-free steel/ECCS (electrolytic chromium coated steel – see separate entries). It should not be confused with black coil (untreated hot rolled coil).

Blackplate is available in single-reduced or double-reduced form, the latter referring to steel coil which is cold reduced part-way to its final thickness, then annealed, before further cold reduction to the final gauge. The result is a stronger and harder product.

Although primarily associated with tin coating, blackplate does have some other applications. For example it can be used as a substrate for enamelled hollowware, and for continuous paint lines (although many pre-painted steel uses a galvanized substrate to enhance corrosion protection), and also for dry battery jackets, lipstick shells and some other packaging.

Blanking

See cutting-to-length.

Blast furnace 

The blast furnace (BF) is a key installation in steelworks using iron ore as their principal raw material. These tall, shaft-like structures extract iron from ore in a continuous thermal process that produces molten iron (pig iron) for conversion into steel in a basic oxygen furnace.

Iron ore, coke and limestone are the main inputs, and are charged to the top of the BF. Preheated air blown into the furnace at a lower level sustains a thermal reaction involving the coke, and releasing carbon monoxide (CO). This reacts with the iron ore (iron oxide) to produce carbon dioxide (CO2) and molten iron – which settles to the base of the furnace and is tapped at regular intervals.

Hot gases rising inside the BF preheat incoming material, initiate ore reduction and convert limestone into CO2 and calcium oxide. This reacts with impurities in the molten iron to form slag which is drawn off.

BFs typically have an annual iron output of 1m-5m tonnes and routinely operate for several years between maintenance stops.

Blooming mill
Blooms

These are large, long, continuously cast pieces of steel with a minimum square section of 150mm x 150mm, but usually much larger. They are cut-to-length immediately after casting.

After reheating, blooms are used to roll medium and large sections, as well as large profiles such as sheet piling, and rails. Sometimes when large “H” or “I” beams are to be rolled, partially shaped blooms called beam blanks or “dogbones” are cast to shorten the rolling process.

Where ingot casting of carbon steel is still the only option, or in the case of certain highly specialised alloy steels where ingot casting produces higher quality material, blooms are rolled from cast ingot in a blooming mill.

Blooms (and billets) are also used for seamless tube making.

Body in white (the)

This is the term used to describe the main structure of a car before fitting any components (engine, seats, transmission, steering etc) and trim. Opinion is divided as to whether the body in white (BIW) includes or excludes closures (doors, bonnet, boot lid etc).

The BIW largely defines the size, shape and strength of a car, and comprises a monocoque structure made from steel sheet pressings welded together by robots. It is a strong, stiff structure and, without closures, accounts for about 20% of final vehicle weight (so about 280-290kg for a typical small/medium family saloon).

Both hot and cold rolled steel coil, most or all of it galvanized, is used to fabricate the parts that make up the BIW.

BOF, BOP, BOS

The basic oxygen furnace converts iron from the blast furnace into steel. This is achieved by blowing oxygen over the molten iron in the BOF vessel, where it combines with and removes carbon as carbon monoxide and carbon dioxide. Unwanted silicon, phosphorus and other elements are also driven off, while added fluxes (typically lime) combine with other impurities to be removed as slag.

The reactions in the BOF vessel generates heat, so ferrous scrap is added to act as a coolant. Scrap can account for up to 30% of the charge weight, which can total several hundred tonnes.

Alternative names for this plant/process are steel converter, BOS (basic oxygen steelmaking), basic oxygen process (BOP), and LD process (after the Linz steelworks in Austria where it was first commercialised in the early 1950s).

Boron steel

The addition of boron to steel allows the achievement of higher strength after hardening by heat treatment, but offers a workable material to the fabricator or manufacturer when in the “as-delivered” condition.

Boron is often added to medium carbon steels to achieve an in-service performance comparable to high carbon and more costly low alloy steels (rather than increasing their carbon and manganese content or adding chromium and molybdenum – with the attendant penalty of reduced ductility during fabrication).

The amount of boron which is added to achieve these characteristics is very small – in the range 0.0005-0.005%.

Traditional applications for boron steels are in wear applications such as shovels/spades, caterpillar tracks, plough shares, punches, but also some spring steels, and more recently in automotive car bodies. Here they have been developed into high strength sheet steels for parts of the body shell and chassis – such as door sills, door pillar reinforcement, cross members, safety beams and bumper reinforcements.

Breakout

This happens when the refractory lining of a blast furnace fails. It is particularly dangerous if this occurs below the molten iron or slag level as these liquids can then spill out. Apart from possible injury or death to operators, breakouts cause loss of production as well as possible damage to ancillary equipment.

Bright annealed

A highly polished, highly reflective, mirror finish on stainless steel coil which is produced by cold rolling between highly polished mill rolls and then annealing the steel in a closely controlled reducing atmosphere – usually a mixture of hydrogen and nitrogen – to prevent any surface scaling or oxidation.
After this treatment, the stainless steel is said to have a “BA” finish.

Bright bar

This is carbon, alloy or stainless steel bar which after hot rolling is later drawn through a die, or machined (turned), to give a close dimensional tolerance, good surface finish and sometimes improved mechanical properties.

The result is a product, also referred to as cold finished bar, which is far more suitable for direct use in engineering applications than in the hot rolled state with its associated surface scale and less precise dimensions.

Bright bar can be of round, square, flat, hexagonal or other cross-section.

Most bright bar is produced by drawing hot rolled bar through a tungsten die after first removing any surface scale and rust by shot blasting or pickling. Another common method is turning (also called peeling) and polishing, and for very accurate dimensional tolerances, drawing or turning followed by precision grinding is used.

Bright finish

A very reflective finish achieved on tinplate or stainless steel by rolling between highly polished rolls with a minimal reduction in gauge.

Brownfield

Brownfield developments are construction projects which take place on land which has had prior industrial, commercial, retail or residential use.

In the steel industry brownfield often applies to sites selected within urban areas for new distribution facilities or additional steel capacity. Such capacity is often located adjacent to, or within the perimeter of an existing steelworks.

See also Greenfield

 

Bulb flats

Bulb flats, or Dutch profiles, are long, hot rolled flats with a rounded bulb along one edge/side, which gives the flat section strength.

The main application is for stiffening plates in shipbuilding, but they are also used in bridge construction. Bulb flats provide good resistance to buckling and can offer a better strength-to-weight ratio than stiffeners such as steel bars and asymmetric angles.

The rounded profile of bulb flats offers and a good surface for paints to adhere to – an important factor in highly corrosive environments such as the ocean.

Bulk ores

These are metal containing ores which are transported in large volumes, rather than in smaller, packaged consignments. The term typically applies to iron ore, but also to non-ferrous ores like nickel and manganese.

Great care has to be taken in the shipping of large volumes of ores as fines, as improper loading can result in liquefaction of the cargo during transit, destabilising and even sinking a vessel.

Bulk sample

A large and representative sample of mineralised rock from an ore body whose mineral content is being assessed for commercial exploitation.

Busheling

This is a ferrous scrap term which originated in the USA and applies to thin uncoated clippings and stamping offcuts from manufacturing operations. Consequently it only applies to new production scrap, rather than scrap generated from obsolete used items. 

An equivalent European grade is E8 new scrap, and in the UK Grade 8A.

North America’s Institute of Scrap Recycling Industries defines busheling as clean steel scrap not exceeding 12 inches (305mm) in any dimension, including new factory sheet clippings, stampings etc. It must not include old auto body steel, must not be coated, and must not include electrical sheet containing over 0.5% silicon.

The European specifications refer to “thin new production scrap” and allow larger sheet sizes, but specify that the scrap should be “predominantly less” than 3mm (0.12in) thick and be prepared in a manner to ensure direct charging to a furnace.

The UK specifications refer to “new loose light steel cuttings” and say limited proportions of galvanised steel can be included by joint agreement between the parties.

C&F

See CFR

Campaign
Capability utilization

The measure of steelmaking activity used by the American Iron and Steel Institute (AISI). It is quoted as a percentage of the United States steel industry’s capability to produce crude steel if all mills had full order books for a sustained period.

Capacity utilisation

This is the usual way to indicate the level of activity at a steelworks or by a steel company. Quoted as a percentage, it is a measure of how much steel is being made compared to what could be produced if all available equipment was being fully employed (sometimes called ‘nameplate capacity’).

Capesize, Panamax, Handymax

These are cargo vessel size categories. Capesize refers to dry bulk carriers that are too big to pass through the Suez or Panama canals. Consequently they have to go round the southern tip of Africa (Cape of Good Hope) or South America (Cape Horn). They are usually around 80,000-160,000 deadweight tons  but can be larger, and typical cargoes are iron ore and coal. Needless to say they require deep berths or trans-shipment facilities on arrival.

Panamax cargo ships are the largest that can go through the Panama Canal, and are usually about 65,000 dwt. Handymax vessels typically carry dry bulk cargoes like steel, are in the 35,000-60,000 dwt range, and are equipped with on-board cranes.

Carbon leakage

This is the shift of industrial activity from one country or region to another because of the penalties associated with excessive carbon emissions, resulting in no net reduction in global emissions.

It is a phenomenon more associated with basic industries like steel, cement and chemicals than with the equally or more polluting power generation sector (because of limitations on electricity transmission distances).

The “leakage” might occur because a polluting company decides to move its activities to somewhere with weaker environmental regulation. Equally it could happen because the cost of environmental compliance results in a polluter in one country reducing or closing activity, but another company or companies in a less regulated part of the world starting, or increasing activity to fill the supply gap.

In the case of steelmaking in advanced industrial economies like Europe, the likelihood of carbon leakage by companies moving elsewhere is further enhanced by the inherently more favourable economics of basic steel production in certain other countries anyway, irrespective of environmental considerations.

Carbon steel

Plain ordinary grades of steel with no significant alloy content.

Carburising
Case hardening

A method of heat treatment to increase the hardness, and therefore the wear and abrasion resistance, of the surface of low carbon steels, while leaving a softer interior which is tougher and more fracture resistant.

The hardness is usually achieved by dissolving either carbon or nitrogen in the surface layer of the steel (processes which are respectively known as carburising and nitriding).

Case hardening can be applied to both carbon and alloy steels, and is usually applied to steels with carbon contents below about 0.2%.

Once treated, these steels can then be used for the manufacture of components like gears and other parts subject to mechanical wear.

Cash settlement

Settling futures or option contracts with cash, rather than by taking delivery of the commodity being traded. The settlement figure relates to the loss or gain that exists on expiry of the contract.

Casing

See OCTG.

Cast iron

See iron & steel.

Casting

The process of turning liquid steel into a solid shape suitable for processing into a finished product by rolling or forging.

Certified Emissions Reductions (CER)

Certified Emissions Reductions are carbon credits, each with a value of one tonne of greenhouse gas emissions which are allocated under the UN Clean Development Mechanism. CERs are valid in a number of voluntary emissions trading schemes. They can also be used in Europe’s Emissions Trading System (ETS) but only to account for a certain percentage of a plant’s emissions.

CFR

Contracts settled on a cost and freight (CFR) basis require the seller, in addition to paying for the goods, to arrange and meet the cost of transporting them to the agreed port of destination. Risk passes to the buyer as goods cross the ship’s rail. Additionally it might be specified that the seller provide appropriate marine insurance. (The terms cost and freight (C&F) and cost, insurance and freight (CIF) were replaced some years ago.)

Charge

In steelmaking this is the collective term for the principal raw material inputs to a blast furnace (iron ore, coke, limestone), electric arc furnace (scrap and/or direct reduced iron) and basic oxygen furnace or steel converter (liquid pig iron, scrap).

Chromium

This hard, steely-grey metal, with a high melting point (1,857C), is best known industrially for its role in stainless steel production, which accounts for the bulk of world consumption.

But it has another very visible application in electro-plating to provide a corrosion resistant decorative or hard wearing finish to carbon steel. Less apparent is chromium’s importance in nickel-rich superalloys, such as are used in aero engines, and in tool steels.

For use in steelmaking, the metal is extracted from chromium ore (chromite) by smelting into ferro-chromium (FeCr), an alloy of iron and chromium, in an electric arc furnace.

To produce stainless steel, FeCr, along with stainless steel scrap, is charged to the steelmaking furnace to achieve at least 10.5% chromium content – although the popular austenitic stainless grades typically contain about 18% Cr.

The main commercially viable reserves of chromite (FeCr2O4) are in Kazakhstan, South Africa and Zimbabwe, as well as Russia, India and Turkey.

CIF

See CFR.

Clean Development Mechanism (CDM)

The Clean Development Mechanism is a United Nations programme under the United Nations Framework Convention on Climate Change (UNFCCC) which allows developed countries (referred to as Annex 1 countries) to invest in emissions reduction projects in developing countries (non-Annex 1 countries) as a cheaper alternative to investing in emissions reductions in their own countries. Projects are awarded a number of Certified Emission Reductions equal to the amount of emissions saved.

Cluster mill
Coated steel

This usually refers to steel which is coated with a thin layer of zinc, tin, paint or plastic in a continuous process prior to sale to traders, stockists and end users. It is more accurate to call it continuously coated steel to distinguish it from batch coated steel.

Most coated steel is in coil or sheet form, but some long products, such as wire, are galvanized. See also: colour coat, galvanizing and tinplate.

Cogging mill

This term is mostly associated with a heavy duty rolling mill for shaping reheated steel ingots into blooms or slabs. It has largely been superseded by the continuous casting of steel directly into these shapes. The mill is a reversing mill, allowing the ingot to pass and re-pass through the rolling stand until the desired profile is achieved.

Prior to their introduction in late 19th century, large industrial hammers were used to reduce ingots to a suitable size and shape for rolling.

Sometimes referred to as a semi-finishing mill, blooming mill or slabbing mill.

Coke

Coke, iron ore and limestone are the principal inputs for blast furnace (BF) ironmaking. Coke provides thermal energy, combines with the oxygen in the ore to release iron, and ensures a permeable physical structure within the furnace to allow hot gases to move upwards, heating the incoming materials, and molten iron and slag to move downwards for tapping.

The quality of coke has a significant influence on furnace productivity and iron production costs.

Coke is produced by heating coal to about 1,100oC in a reducing (oxygen deficient) atmosphere. This is done in coke ovens, and volatile compounds like tars are released along with hydrogen and methane to leave a carbon-rich product.


Desirable qualities for coke are high carbon content; low sulphur, phosphorus and moisture content; low ash residue; and physical strength.


Coke consumption per tonne of liquid iron produced has fallen significantly over time and currently is around 400kg. Consumption, and costs, can be further reduced by the injection of pulverised (non-coking) coal.

Coke oven

See coke.

Coking coal

Unlike thermal or steaming coal used in power stations or for industrial or domestic heating, coking (or metallurgical) coal has unique properties that suit it to iron making.

A key characteristic is that when heated in the absence of air, this coal, unlike steaming coal, will form the hard, sponge-like material known as coke. As steelmakers are looking to produce high iron purity, the coal needs to have high carbon, but relatively low ash, sulphur and phosphorus content.

Also, coke should not physically break down as it travels down through the blast furnace (along with iron ore and limestone), so helping to retain permeability in the ironmaking burden.

The terms “hard”, “semi-hard” and “semi-soft” actually refer to the coal’s readiness to form coke (“hard” is best), and not its physical hardness. However, “hard” coal does happen to produce physically hard coke.

About 10% of world mined coal is coking coal, with the major exporters being Australia, Canada and the USA, followed by China and Russia.

Cold drawing

This is a process for changing the cross-sectional size or profile of steel in bar or coil by pulling (drawing) the unheated metal through a die of smaller diameter and/or different cross-section. The advantages include improved surface condition, good tolerances and better mechanical properties – such as higher tensile strength.

Shaped bar and wire are the principal steel products made by this technique.

In the production of wire a succession of drawing operations can reduce wire rod down to diameters of as little as a few microns (one thousandth of a mm). Cold drawn bar typically has round, square, hexagonal and octagonal profiles, but the larger the diameter, the closer the profile of the feedstock must be to the final shape, since there are strict limitations on what changes can be achieved with unheated steel.

In general the term cold drawing relates to long products. It should not be confused with deep drawing of sheet or drawn-over-mandrel tube making (see separate entries).

Cold end

See hot end.

Cold finished bar
Cold reduced steel

See cold rolled coil.

Cold rolled coil (CRC)

Flat rolled steel that has been rolled on a cold strip mill to reduce thickness and improve flatness. This form of gauge reduction also referred to as cold reduction.

Cold working

This is when the shape of a piece of steel is changed by processes such as rolling, drawing and stamping at room temperature (or well below the metal’s recrystallisation temperature).

Cold working increases a metal’s hardness and strength, improves surface quality, but reduces ductility.

Colour coat

Colour coated steel, or prepaint, is steel coil to which a paint, powder or film coating has been applied in a continuous process prior to it being cut and shaped. It provides a durable uniform surface finish, and can be an alternative to conventional post-manufacture painting of steel parts.

Steel coil is coated on one or both sides in a process similar to that used for newspaper/magazine printing. Rolls apply first a primer and then a topcoat to the moving steel strip. The substrate is usually cold reduced galvanised coil, but galvanised HRC, and even uncoated coil is used.

Colour coat avoids strict environmental controls at manufacturers’ paint shops, since the onus of compliance is on the coil coater.

Building applications account for around two thirds of consumption, with cladding on steel frame buildings a well known use. But it is also widely used for domestic appliance casings and for some furniture.

A real breakthrough would be prepaint’s use for automotive bodywork, but there are issues regarding the stamping and bending of complex shapes and then joining them without surface damage.

Compensated gross tonnes (cgt)

Compensated gross tonnes (cgt) are a measure devised by the OECD to provide a more accurate indicator of the amount of work needed to build a ship, since vessels can vary considerably in their complexity. The value is determined by multiplying the gross tonnage by pre-agreed constants. See also deadweight tonnes, gross tonnes and lightweight tonnes.

Concentrate

A fine powder-like intermediate product between ore and metal, from which much of the waste mineral has been eliminated, leaving a much higher concentration of the required mineral than in the original ore. Equipment used is known as a concentrator.

Concentrator
Conditioning

In the transition from cast steel to steel products, conditioning is the removal of surface defects from semi-finished steel like blooms, billets and slabs prior to rolling. This might involve grinding, machining or scarfing (removal of unwanted metal by torch cutting).

Contango and Backwardation

These are terms that will be familiar to steelmakers who have for some time hedged their zinc, nickel or tin cost exposure on commodity exchanges, but will now be of interest to a wider steel audience now that futures trading in steel is underway.

On any given day in a normal futures market the forward contract price is higher than that day’s cash settlement price. This is principally because of the cost of storing and insuring a consignment of metal earmarked for later delivery. In these circumstances the market is in contango.

But there are times when cash prices rise above forward prices, usually when a near-term supply shortage affects market sentiment. When this happens the market is in backwardation.

Commodity exchanges can sometimes step in to limit the extent of a backwardation.

Continuous casting

This is a process for converting liquid steel directly into a semi-finished shape suitable for further processing.

Steel is poured into the top of a long mould which at the point of entry is vertical, but which gradually curves to end horizontal. It has the cross-section of the desired semi.

As the steel passes down the mould it solidifies, emerging as a continuous strand which is cut into useable lengths. “Conticasters” (as they are often referred to) are used to produce slabs (for rolling plate and strip), blooms (for sections) and billets (for light sections and bars).

The key attractions of the process over its predecessor (casting discrete lumps or ingots of steel), are higher productivity and lower costs, as it avoids having to roll ingot into slabs or blooms. Costs can be further reduced by casting cross-sections closer to the finished product (typically beam blanks for beams, or thin slab and even strip casting for flat products).

Continuous mill

See reversing mill.

Conversion cost

A measure of the cost of processing material from one form into another. Often used to describe the cost per unit of production of a major transformation such as steelmaking, taking account of all costs – raw materials, energy and other consumables, labour, maintenance, depreciation, servicing capital employed. It can also be applied to more incremental changes – such as producing hot rolled coil from slab.

Converter

See BOF.

Corex

This is an ironmaking technology which, unlike the blast furnace, uses steaming (non-coking) coals, so avoiding the higher cost of coke.

It is a two-stage process where lump ore, pellets or sintered iron ore, or a mixture of these, is firstly charged to a reduction shaft where it is transformed into direct reduced iron by a reducing gas. The hot DRI then enters a melter/gasifier, along with coal and oxygen, where liquid iron and slag are produced and periodically tapped off.

Corex was developed by VAI (now Siemens-VAI), and after first operating commercially in the 1980s is now in service with a handful of steelmakers in Asia and in South Africa.

The developer says Corex’s emission values already comfortably meet future European standards.

Competing technologies include Finex, HIsmelt and Technored.

Countervailing duty
Crucible swelling number

The CSN, or free swelling index (FSI), is widely used to give an indication of the suitability of a particular coal for metallurgical coke production.
The CSN is determined by comparing the shape of a coke button produced when a piece of coal has been heated to 820oC in a covered crucible for several minutes against some standard profiles. The sample is then assigned a CSN value ranging from ‘0’ for no swelling, to ‘9’ for a high degree of swelling.
Coals with a CSN of 4 or less are generally deemed to be unsuitable for metallurgical coke production, while those with a higher value will produce coke of varying hardness – although there appears to be no direct correlation between CSN values and coke strength because of variables in the composition of different coals.

Crude steel

The normal measure of steel output. Crude steel is either liquid steel or cast steel before being further worked.

CSR

This is an abbreviation of ‘coke strength after reaction with CO2’. It is one of the key parameters used in evaluating the quality and therefore setting the price of coking coals (metallurgical coals) used in making blast furnace coke.

CSR is quoted as a percentage, and a CSR of 50% is generally regarded as the minimum for a commercially traded hard coking coal. Premium grades will have CSR’s well above that – typically in the mid-sixty percents.

The CSR value is taken along with other key parameters when assessing coking coal quality. Premium coals will have higher volatile matter content, but a lower ash, sulphur, phosphorus and moisture content.

Blast furnace operators will usually operate with a blend of coking coals to achieve the performance they require.

Cupola

This is a type of furnace, similar in concept to the blast furnace but very much smaller, that is widely used to produce liquid iron in foundries.

It is essentially a refractory lined steel vessel around 6-10 metres high into which cold pig iron, and perhaps some iron scrap, plus coke and a limestone flux is charged. Combustion is assisted by forced air.

This continuous process yields high quality iron at low cost for applications ranging from automotive components to drain covers.

Cupola melting is estimated to produce well over half the liquid iron used worldwide for grey and ductile iron castings. However, tighter environmental regulations are one factor pressing on users of this method.

Cut-off grade

The grade or concentration of iron (or other mineral) in a deposit below which it is considered to be uneconomical to mine and process.

Cutting-to-length, slitting, blanking

These are key stages in the preparation of flat rolled steel for the final customer, and they are usually undertaken by service centres.

The large coils produced by steelworks weigh 25 tonnes or more and are typically upwards of 1,500mm wide. Few customers can accept steel in this form, so the coils often have to be broken down into more manageable sizes.

Sometimes they are transformed into smaller, narrower coils by a combination of slitting (to reduced the width) and then cutting off a certain length of the main coil, and re-coiling this, to achieve the required size. A single coil may be slit into varying widths in one operation

Alternatively coils may be cut into sheet by removing specific lengths from the coil (cutting-to-length). This may follow a slitting operation if sheet which is narrower than the incoming coil is needed.

Less frequently, coil or sheet is transformed into a large number of identical flat shapes of precise dimensions ready for direct use on a production line by the steel end customer (blanking).

Deadweight tonnes (dwt)

This is a measure of the carrying capacity of a vessel (cargo, fuel, stores, passengers, crew etc). See also gross tonnes, lightweight tonnes and compensated gross tonnes.

Debar

See Rebar

Decarburisation

In steelmaking, decarburisation, or the reduction of carbon content, is one of the key roles of the basic oxygen furnace process for converting iron into steel. It is achieved by blowing oxygen over molten iron where it combines with and removes carbon as carbon monoxide and carbon dioxide.
But once steel has been cast and rolled, further decarburisation may occur at the surface during subsequent heat treatment or rolling. This is because when steel is hot, carbon reacts with oxygen resulting in a low carbon composition in the outer layers of the steel. Loss of strength and ductility and surface cracking are typical effects, and this may be undesirable, depending on the intended applications for the metal.
Decarburisation can be prevented or inhibited by restricting the duration of heat treatment or processing the steel in an inert atmosphere.

Deep drawing steel

Deep drawing is a mechanical process in which steel sheet is severely deformed to make a pronounced shape with a uniform thickness – such as a can body, canister, box or specific component. Consequently, deep drawing steels have properties that allow a rapid and radical change in shape in a die without tearing or rupture.

These steels are widely used in the food and drinks packaging industry, in the automotive industry, and in general engineering. Car makers typically use hot rolled deep drawing steels for body and structural parts, chassis components and wheel rims, and steel in the cold reduced condition for complex body parts, door sections, floor panels and other parts.

Deep-drawing steels have a low carbon and low manganese content and, depending on application, low quantities of residual elements like titanium, chromium, nickel and copper. They can be coated or uncoated, and some stainless steels can be deep drawn.

Deleterious material

Undesirable content in an ore that can cause complications in processing. In iron ore common deleterious elements are: Sulphur (S), Phosphorous (P), Aluminium (Al) and Silica (Si).

Derivative

A generic term for futures, options or swaps contracts which are arranged either directly between two parties (over-the-counter) or on a commodities exchange (exchange traded).

Descaling

Scale, a layer of oxide, is formed on the surface of steel during heating and hot rolling, and descaling is essential before any further processing takes place in order to prevent this unwanted material from damaging the surface of the steel.

In the case of hot rolled coil (HRC), descaling takes place immediately after rolling is complete using high pressure water jets positioned along the mill’s run-out table. However, HRC is also usually pickled prior to cold rolling to remove any residual scale and any oil or grease used to protect the steel against corrosion during storage or transit (see also ‘pickled & oiled’).

In the case of long products, hot rolled bars are either pickled or shot blasted before downstream operations such as bright drawing (see also ‘bright bar’).

Desulphurisation

To achieve high quality steels with the desired range of physical properties, various impurities need to be removed from the liquid metal before it is cast and further processed.

One of the most detrimental impurities is sulphur, since it affects both the overall quality of the steel and its surface condition. The only exception is that in controlled amounts it can confer some advantages to machining grades of steel.

Sulphur content is reduced to required levels by adding a reagent (a substance which creates a reaction) to the hot metal. The most commonly used reagents are lime, calcium carbide and magnesium.

Magnesium has emerged as a favoured additive as it has a high affinity for sulphur. Also, unlike the other two reagents, magnesium dissolves in the melt, which results in a more effective reaction.

With blast furnace based steelmaking, desulphurisation is usually performed on the liquid iron prior to the steelmaking stage. With the EAF route it is performed in the ladle furnace.

Direct reduced iron (DRI)

Direct reduced iron (DRI) is a metallic iron product used in electric arc furnace (EAF) steelmaking. It is produced from iron ore in a thermal, natural gas based process, & because of its purity and consistency tends to carry a price premium to scrap. It is sold as pellet, lump or in briquetted form (HBI – hot briquetted iron).

DRI is principally used as part of a furnace charge when EAF steelmakers need a high quality raw material to dilute undesirable elements in their main scrap feed. It is mostly favoured by mills producing sheet or special quality long products.

Direct shipping ore

This is iron ore which is readily accessible at the mine, and which has a sufficiently high ferrous content (normally 60%-plus) to be sold to steel mills without beneficiation prior to shipping.

Double cold reduced
Steel strip which undergoes a second pass through a rolling mill after being annealed.
Drawing

This a process whereby the shape and/or dimensions of rolled steel sheet or long product, such as bar, wire or tube, are altered.
In the case of steel sheet, drawing takes place in a press to change the sheet from a flat to a shaped profile (see also deep drawing).
With long products, these are drawn through a die on a drawbench to reduce diameter and increase length.
One category is bright drawn steel – usually bar which has been drawn after rolling to ensure good dimensional accuracy and provide a bright finish.
Drawing is generally, but not exclusively, a cold working technique as it is usually conducted at room temperature. See also deep drawing.

Drawn and wall ironed (D&WI)

This is a precise and high speed process for manufacturing cans from either tinplate or aluminium sheet, and is mostly used for producing beverage cans.

The sequence starts by stamping shallow cups from the incoming sheet. These cups, supported internally to prevent their sides collapsing, are then forced though a succession of dies, each of slightly smaller diameter than the previous one. The result is progressively thinner side walls, increased metal surface area and therefore greater depth of container.

The base of the resulting cans are then given a concave profile and the open ends trimmed to ensure uniform height. After cleaning to remove all machining lubricants, cans are printed and the rims ‘necked’ (slightly reduced in diameter) and made ready to receive their tops after filling by the customer.

Drawn-over-mandrel tube

This usually refers to a finishing stage for welded steel tube to achieve good dimensional accuracy and concentricity; uniformity of wall thickness, diameter and mechanical properties; good hardness; high yield and tensile strengths; provide a high standard of surface finish; and ensure weld integrity. The resulting tube requires minimal further processing prior to use.

The welded tube is first drawn through a die and then over a mandrel*. A range of finished tube sizes may be made by this route, and several dies and mandrels may be involved to achieve the final tube size.

Drawn-over-mandrel (DOM) is frequently used in the high volume production of tube for demanding mechanical applications such as in hydraulic systems.

*Solid bar whose diameter is close to the tube’s desired inside diameter.

Drill pipe

See OCTG.

Dry metric tonne unit

This is the internationally accepted unit of measure for iron ore pricing.

A dry metric tonne unit (dmtu) is 1% of iron (Fe) contained in a tonne of ore, excluding moisture.

The price per tonne of a consignment of iron ore is calculated by multiplying the cents/dmtu price by the percent Fe content of the ore in that shipment.

For example, a 67% Fe content iron ore will priced at the contracted dmtu price multiplied by 67, a 55% Fe content ore at the dmtu price multiplied by 55, etc.

Iron ore contract prices are quoted in US$ cents.

Dual phase steel

These steels are so named because their microstructure contains two phases, typically combinations of ferritic and martensitic phases, or austenitic and ferritic phases.

These are high strength steels, which usually have a ferritic/martensitic microstructure in the case of carbon steels, and an austenitic/ferritic structure in the case of stainless steels.

A ferritic steel’s structure is low in carbon and relatively soft, an austenitic steel is soft and ductile but capable of a higher carbon content than ferrite, while a martensitic structure is very strong and hard.

Dual-phase carbon steels are a class of high-strength low-alloy steels which are particularly attractive in applications such as the automotive industry because of their combination of high strength, good forming properties and excellent energy absorption characteristics.

Dual-phase stainless steels are well suited to very demanding operating environments because of their excellent corrosion resistance.

Ductility
Dumping
Duplex stainless

This steel combines the properties of austenitic and ferritic stainless, the two most widely used grades.

With its approximately 50% austenite and 50% ferrite microstructure, duplex stainless is characterised by high strength and corrosion resistance, along with greater hardness and ductility than ferritic grades and similar ductility, though less toughness, than austenitic stainless.

First produced in Sweden around 1930, Duplex steel achieved more enhanced properties 50 years later when improvements in refining technology allowed the introduction of nitrogen alloying. The composition of the main alloys is chrome 18-26%, nickel 4-6.5%, and molybdenum 0-3%.

Duplex stainless is often specified for oil/gas applications, process plants like pulp, paper and desalination, and for heat exchangers.

Dutch profiles
ECCS

Electrolytic chromium/chromium oxide coated steel, is cold rolled coil with a thin coating of metallic chromium (next to the substrate) and chromium hydroxide surface layer.

Electric arc furnace (EAF)

Electric arc furnaces produce steel directly from scrap. This can be supplemented by other inputs like direct reduced iron and pig iron. They account for about one third of global steel output. Basic oxygen furnace (converter) steelmaking accounts for the rest.

 

 

The EAF is a refractory-lined vessel with a retractable cover through which large graphite electrodes are lowered once the scrap has been charged and the furnace top closed. EAFs are usually of 60-150t capacity per melt, but occasionally larger. However, they are usually much smaller than BOFs.

 

 

Melting occurs due to the energy released by arcing between electrode and scrap. There are normally three electrodes, but only one with direct current furnaces.

 

 

Much effort has been directed at minimising the time from scrap charging to steel pouring (tap-to-tap time). It is now standard practice to transfer steel to a separate furnace for alloying modifications (secondary metallurgy) to free-up the EAF for the next charge. Scrap pre-heating and oxygen injection also raise productivity and reduce energy use.

Electrical Steels

 The hallmark of these sheet steels is their good magnetic properties. They concentrate magnetic fields and are easily magnetised and demagnetised.
 
 Electrical steels have a low carbon content but can contain up to around 3% Si – hence the alternative name silicon steel – and come in two forms: grain-oriented (GO) and non-grain-oriented (NGO).
 
 GO sheet has its internal structure aligned in one direction during cold rolling and annealing to give very good electrical properties in one direction. NGO sheet has a random internal structure and uniform magnetic properties in any direction.
 
 GO applications are principally in transformers for stepping-down voltage – such as from power station to consumer. NGO sheet is used in rotating electrical equipment like motors and alternators – from massive rolling mill motors to computer disc drives.

Electro-galvanized

See galvanized.

Emissions Reduction Units (ERU)

Emissions Reduction Units are carbon credits, each with a value of one tonne of greenhouse gas emissions, which are granted to projects in the Joint Implementation (JI) scheme (see separate entry). Like Certified Emissions Reductions they can be used under the European Emissions Trading System (ETS), but only to account for a certain percentage of a plant’s emissions.

Emissions trading scheme (ETS)

An emissions trading scheme (or system) is a way to price carbon emissions and thus encourage investment in greenhouse gas emission reductions. It also indirectly serves to make steelmaking more efficient.

At the end of a year plants must relinquish carbon credits equal to the value of the emissions they produce. For example, a plant that emits 1m tonnes of greenhouse gases in a year will have to hand over 1m carbon credits at the end of that year.

In the European emissions trading system, the only fully functioning international scheme, most plants currently receive their carbon credits for free from national governments. They therefore only have to buy additional credits when their emissions exceed expectations.

However, this should change slowly from 2013 when phase III (2013-2020) of the programme begins. The number of free allocations is expected to decrease, forcing plants to buy an ever greater number of credits on the market or cut their emissions.

Energy optimising furnace (EOF)

The energy optimising furnace (EOF) burns coal, enhanced by oxygen injection, to generate the thermal energy needed to preheat and then melt a mixture of scrap and pig iron, or other steelmaking raw materials, in an enclosed hearth.

It is a vertical process with the hearth at the base, and chambers above in which scrap etc is preheated by off-gases before descending into the melting zone. Steel is tapped off at the bottom of the vessel. The technology was pioneered in Brazil, but most working examples are in India, and commercial units are typically in the 500,000-600,000 tonnes/year range.

The EOF is recognised as a way of producing good quality steel with relatively low investment and operating costs, and is ideal where power networks cannot support the heavy electrical loads imposed by electric arc furnace (EAF) steelmaking. However, the EOF may be more environmentally damaging than the EAF.

Engineering steels

See SBQ

ERW pipe

Both electric resistance welded (ERW) and submerged arc welded (SAW) tube or pipe is mostly produced by first forming steel sheet or plate into a cylinder and then welding the longitudinal gap to form a seam.

With ERW the seam is progressively welded using a combination of heat and pressure. Resistance to electric current generates heat in the weld locality, taking the temperature of the steel to just below its melting point. Simultaneously, mill rolls located around the pipe force the two edges of the formed sheet/plate together to join them.

ERW is generally used for smaller diameter tube/pipe with relatively low wall thicknesses.

See also SAW pipe.

European Union Allowances (EUA)
European Union Allowances are carbon credits, each with a value of one tonne of CO2 emissions, and are the main kind of credit in Europe’s Emissions Trading System (see emissions trading scheme entry). Currently, in phase II (2008-2012) of the programme, most EUAs are allocated by national governments to polluting plants. Plants with more EUAs than they need can sell them on carbon markets, while plants which emit more gases than they have allocations for have to buy EUAs to cover the shortfall. In phase III (2013-2020) of the ETS free allocations of EUAs will be slowly reduced, forcing facilities to cut emissions or buy more credits to cover their emissions.
Ex-works

The ex-works price of a consignment is the price at the plant/works gate. No transport included, as distinct from CFR, C&F, CIF etc.

Exchange traded option

This is a contract which gives the holder the right, but not the obligation, to buy or sell a stipulated quantity of a specified asset at a predetermined price (strike price) on a regulated exchange on or before a set future date.
Exchange traded options can either be “call” options or “put” options, the former conferring a right to buy, the latter the right to sell.
These options have the attraction of standardised contracts – unlike over-the-counter options whose terms can be customised – liquidity, price visibility and the use of a clearing house, which ensures the contract is fulfilled.

Extrusion

Extrusion is method of producing lengths of steel to a particular profile by forcing the metal though a die cut to the cross-sectional shape required. The result is a profile with good dimensional tolerances (near net shape), though not as dimensionally accurate as a machined part.

The method is used to produce a wide range of shapes, from rounds, squares, “L” shapes, “T” shapes and tube, though to complex sections that can be difficult to make by any other method. The latter are often specific to a particular application, and a stock of ready-made dies will be held by an extrusion works ready for when these sections are needed.

The starting material for an extrusion press is usually a pre-heated round billet and, depending on steel type, sections up to a size that will fit within a 250mm diameter circle would be typical of what an extruder can produce.

The method is also widely used for non-ferrous metals, particularly aluminium, as well as plastics.

Feasibility study (bankable feasibility study)

A detailed study looking at the technical, economic, social and legal viability of a mining project. Risks are identified and quantified. Provides enough information to decide whether or not the project should go ahead. A bankable feasibility study is the basis on which lenders provide the necessary capital for a project.

 

Ferritic steel
Ferro-Alloys

These are the condiments of steelmaking. They are alloys of iron with other key elements, which, when added to the steel, melt determine whether the metal will have the properties which make it suitable for use as paper clips, a car body, an aircraft undercarriage, a beam in a high-rise building, etc.

Three ferro-alloys account for most demand: ferro-manganese, the most widely used, confers strength and hardness, as well as desulphurising and deoxidising the steel; ferro-silicon is a deoxidiser that improves steel strength, heat resistance and magnetic/electrical properties; and ferro-chrome, which is essential for making stainless steel, but is also used in other alloy steels to give hardness and impact resistance.

Ferro-nickel

This is an alloy of nickel and iron which provides a convenient way of adding nickel units during the production of stainless steel, other nickel containing steels, and foundry alloys.

 

Ferro-nickel typically contains 20-38% nickel with most of the balance as iron, plus traces of other elements which can include carbon, phosphorus, cobalt, copper and silicon.

 

Although ferro-nickel is mostly used in producing austenitic and duplex grades of stainless, it can also be present in small quantities in ferritic and martensitic grades.

 

This ferro-alloy is typically produced in convenient sizes and forms – such as small ingots, pellets and cones - for ease of charging to the stainless steel melting/refining process.

See also nickel, nickel pig iron and ferro-alloys.

Ferrous

Containing iron. Used to distinguish iron and steel from non-ferrous metals.

Fines

Material that passes through a standard screen on which coarser fragments are retained. In iron ore terms, fines is used to classify material that is usually between 1-10mm in size.

Finex

See Corex.

Finished steel

A steelworks' end products - such as bar, plate, beams, coil.

Flat products

Plate, strip and sheet, including strip/sheet coated with zinc, tin or other materials.

Flotation

A liquid concentration process in which the desirable mineral particles attach themselves to bubbles and float away from the waste particles.

Flux

Limestone or other slag-forming material charged to a furnace to remove impurities from the iron or steel.

FOB, FOT

A sales contract negotiated on a free on board (FOB) basis means the seller pays for the goods and the cost of transporting them to the port of shipment and loading them. The buyer pays for shipping, unloading, and transportation to the final destination, as well as insurance. Risk passes to the buyer as goods cross the ship’s rail. Free on truck (FOT) places similar conditions on the supplier, but at his premises, when goods are to be transported to the customer by road.

Forging

This is a way of producing individual metal parts by mechanical impact. It is suitable for working a wide range of steels, and can done with the metal cold, warm or hot. Forging differs from casting in that the metal changes shape while in a solid rather than molten state.

Forgings are used principally where strength and in-service integrity are key requirements. They are stronger than cast or machined parts because the mechanical deformation allows the grain structure of the metal to closely follow the part’s finished shape.

Cold forging tends to be for smaller parts, and offers precise dimensions and high productivity. With warm forging the ductility of the metal is increased, so reducing tool loadings. Hot forging, which is performed at the metal’s recrystallisation temperature, allows deformation of larger workpieces. Examples would include shafts for power station turbines or jumbo jet main undercarriage components.

There are a number of forms of forging which involve containing the metal workpiece to a greater or lesser degree. The starting material may be steel bar, billet or ingot, and this is often sourced externally from steelmakers.

Formability

This describes the ability of steel to undergo deformation into a new shape without losing its structural integrity, and to retain the new shape without partly or fully springing back to its original profile, or curling at the edges into an unwanted shape.
Formable steels will have good ductility (ability to change shape without failure).
It is because of its strength and good formability, along with its relatively low cost and ease of joining, that steel finds such a wide range of applications.

Free-cutting steel

Also known as free-machining steel, this has very good cutting properties during mechanical machining operations like drilling, turning and milling. It is used for making engineering components and is most commonly supplied to the machinist as hot rolled, cold drawn, turned or precision ground bar. These are typically round, square or hexagonal.

Good free-cutting steels will allow fast material feed rates and high cutting/drilling speeds (for maximum productivity), low cutting forces (for long tool life), and generate swarf (steel offcuts) that is easy to clear away from the machining area. A key feature of these steels is that they allow good dimensional tolerances and a good surface finish to be achieved.

The key element in making these steels so machineable is lead, and to some extent sulphur. Apart from carbon, the other main constituents are manganese, phosphorus and silicon. Adding tellurium enhances machining rates. (See also, leaded steel.)

Full Hard

Full Hard is a category of temper that applies to cold-reduced flat-rolled carbon and stainless steels.

During cold reduction from hot rolled coil the characteristics of the steel change and it becomes work hardened. This full-hard steel is often supplied without any subsequent annealing to soften its structure, although the mill or customer may pass the coil through a tension-leveller to improve flatness.

Full-hard steel, with its minimal ductility and formability, has limited direct use, and is really for flat working applications and those involving minimal bending and forming, with generous radii. It is resistant to impact.

However, much full-hard coil is subsequently hot-dip coated with zinc or tin, or is pre-painted. The heat involved in these operations tempers the steel, increasing its ductility and widening its applications.

Half-hard sheet is more formable, and can be bent up to 90 degrees around a radius equal to the sheet thickness.

Full recourse financing
Futures contract

In commodities a futures contract is an agreement between two parties to buy or sell a specified amount of a commodity, on an agreed future date, at a price that is set at the time that the contract is agreed.

Futures contracts are traded on a futures exchange, such as the London Metal Exchange, and are sometimes referred to as exchange traded derivatives.

It is possible to have contract settlement dates in excess of two years forward.

A common variation on a futures contract is an options contract. This gives the buyer, or holder of the contract the right, but not the obligation to exercise the futures contract.

Galvanizing

This is the application of a thin layer of zinc or zinc-aluminium alloy to steel to provide corrosion resistance. The two principal coating methods are continuous galvanizing and batch (or general) galvanizing.

Continuous galvanizing is used to coat flat-rolled steel (mostly cold reduced, but some hot rolled), and also wire and tube. Zinc is applied either by hot-dip coating (the steel passes through a pot of molten zinc) or electrolytic coating (deposition takes place in a series of electrolytic cells). Hot dip is the most common method as it is cheaper.

The key stages on a continuous hot-dip line for strip are pre-cleaning, heating, coating, air-knife (to control coating thickness), cooling and re-coiling. An electrolytic line has no heating or cooling stages.

Continuous lines operate with an endless steel strip created by welding the end of one coil to the start of the next. This highly productive coating process can typically throughput 200,000-500,000 tonnes/year of coil.

Batch galvanizing is the coating of individual finished items or components (typically street furniture) by dipping them in a large bath of molten zinc.

Galvannealed sheet

A hot-dip galvanised sheet which after the zinc coating stage on a continuous galvanising line passes through a further furnace. This re-heating enables iron in the carbon steel strip to migrate into the zinc layer to form a zinc-iron alloy.

Galvannealed strip has a dull grey appearance without the characteristic spangle of hot-dip, and is both easier to weld and smoother than a conventional zinc finish. These characteristics make it popular with car manufacturers.

Gangue

The worthless minerals extracted when mining an ore deposit.

Gauge

See reversing mill.

Global Depository Receipts

These are certificates issued by an international bank in more than one country denoting ownership of foreign-based shares, and they can be traded in various capital markets around the world.

Global depository receipts facilitate the trading of shares. They are frequently used by companies in emerging markets seeking to raise funds by listing for the first time on a major foreign stock exchange.

Very similar in concept and use are American depositary receipts.

In the steel industry, global depository receipts have featured in moves by Russian mills such as Evrazholding, Severstal and Novolipetsk to list on the London or other overseas stockmarkets.

Global Warming

What is...global warming?

Global warming is a term used to describe the increase in the Earth’s temperature due to man-made and other emissions of “greenhouse gases” over the last 300 years or so.

Greenhouse gases are released mainly by burning fossil fuels, like coal, oil and natural gas; they include carbon dioxide (CO2), methane (CH4) and nitrous oxide (N2O). Steelmaking produces large quantities of CO2.

The so-called “greenhouse effect”, whereby the Earth’s atmosphere traps the sun’s energy, is exacerbated by the release of greenhouse gases because they act like the glass in a greenhouse – letting sunlight in, but preventing its heat from escaping.

 

Grade

The metal content of an ore measured in grams per tonne or as a percentage.

Green pipe

This steel pipe or tube is generally produced to J-55, and is thus suitable for OCTG duties. However, it comes with a slightly altered chemistry, generally higher carbon and manganese, which allows it to be upgraded to N-80, L-80 or even P-110, via heat treatment like quenching and tempering.

Greenfield

This describes the construction of anything from a manufacturing or distribution facility to a retail or housing development on previously undeveloped land. It may be agricultural land, an urban open space, or just open country.

See also Brownfield

 

Gross tonnes (gt)

Gross tonnes (gt) are a measure of the total internal volume of a ship. One important application is in setting crewing levels. See also deadweight tonnes, lightweight tonnes and compensated gross tonnes.

H-beam
Hardgrove grindability index (HGI)

This measure of grindability of coal was developed by an American, Ralph M. Hardgrove. The test involved indicates how difficult it would be to grind a particular coal to a certain particle size.
Grindability is assigned an oH value (eg. 55oH), and the smaller the numerical oH value, the more difficult the coal is to grind.

Hardness
HBI (hot briquetted iron)

See DRI.

Heat treatment

This involves the heating and then cooling of metal, and is used to alter steel’s internal structure, and therefore its properties, without changing its shape and size.
Although often associated with increasing the strength of steel, it can improve formability, restore ductility or make the steel softer.
Heat treatment techniques include annealing, carburising and quenching.

Heavy sections

Beams and columns used to build large structures such as multi-storey buildings and bridges.

Hematite or Haematite

An iron oxide mineral (Fe2O3) widely used in the production of pig iron in a blast furnace. It is generally cheaper and easier to beneficiate than magnetite (Fe3O4), and also requires a lot less energy to crush and grind. However, it can contain impurities. (see also iron ore)

High speed steel

High speed steel (HSS) is so called because of its ability when used for cutting tools to cut faster than those made of high carbon tool steels.
Key properties include high working hardness, wear resistance and toughness, good compressive strength and an ability to perform at temperatures up to 5000C without losing hardness
This performance is achieved through the addition of several alloying elements such as chromium, tungsten, molybdenum, vanadium or cobalt, as well as through appropriate high temperature heat treatment. Carbon content is usually below 1%.
The main use of high-speed steels is for the manufacture of cutting tools such as drills, milling cutters, gear cutters, saw blades etc.
HSS can be coated – typically with titanium nitride – to increase a tool's hardness and lubrication.

High strength, low alloy (HLSA)

High strength low alloy is a term applied to flat rolled steels which, through the addition of small amounts of various specialised alloying elements, exhibit good strength with excellent formability. Corrosion resistance can also be enhanced.

Typically these steels have moderately low carbon content (0.05-0.1%) and use one or more of the alloying elements niobium (columbium), titanium and vanadium at around the 0.01-0.05% level, hence their alternative name microalloyed steels.

HSLA steels have found widespread use in applications such as the automotive industry, where good formability is needed during body panel production, but strength is required for the in-service conditions encountered by vehicles.

Hire Rolling
HIsmelt

See Corex.

HMS 1 & HMS 2

HMS stands for heavy melting scrap, and 1 & 2 are the two grades within that definition. They are widely traded, particularly in the western hemisphere.

Both HMS 1 & 2 comprise obsolete scrap only. That is iron and steel recovered from items demolished or dismantled at the end of their life.

Because both grades guarantee a minimum piece thickness – at least 1/4inch (6.3mm) for HMS 1, and 1/8in for HMS 2 – consignments have a high density. Both also have defined maximum dimensions (usually 60in x 24in), and should be prepared to facilitate handling and charging to a furnace.

This density, sizing and preparation makes for efficient furnace operation by minimising the time to charge enough scrap for a full melt. In contrast, thin mixed scrap greatly increases charging time, cutting furnace productivity.

Variations on maximum piece size are covered by ISRI (North America’s Institute of Scrap Recycling Industries) codes. HMS is usually traded as a blend of 1 & 2, either a premium blend (80:20) or lower grade mixes (70:30) and (60:40). Other major heavy scrap grades include Japan’s H2 and A3 from the CIS.

Home scrap

See scrap.

Hot band

See hot rolled coil.

Hot end

Both hot end and cold end are terms used in connection with steelworks which are integrated from iron/steelmaking through to rolling and coating.
Hot end refers to stages in which metal is either molten, or is solid but can only be worked at elevated temperatures. So it includes the blast furnace and converter (iron ore based steelworks), and electric arc furnace (scrap based steelmaking), along with any secondary metallurgy stages, casting and hot rolling.
Cold end is a term for production stages performed with the metal at ambient temperature, which for flat products mostly includes cold rolling and coiling/decoiling, along with operations like surface treatment and coating, where the metal may be undergo temporary reheating heating – as in hot dip galvanizing, tinning or painting.
Long products are generally hot rolled to their final shape, so ‘cold end’ includes further processing like wire drawing, mechanically applying a bright finish to stainless steel, and despatch operations like bundling.

Hot idling

This is a procedure for temporarily maintaining a furnace on standby without producing any iron. The main chamber is kept fully charged with coke (but not with limestone and iron ore, the two other bulk ingredients for iron making), and the amount of air entering the furnace is significantly reduced, slowing combustion while maintaining the refractory lining at temperatures that prevent deterioration. The term “banking” is also used for this procedure.

Blast furnaces are not usually hot idled for more than a few weeks unless all the iron is completely drained from the furnace, and they can be returned to full iron making capacity within a matter of days.

Normally blast furnaces can be operated continuously for up to about 15 years between major maintenance work, a period known as a “campaign”.

Hot rolled coil (HRC)

The most common form of flat steel product. Rolled on a hot strip mill, it is typically 2-25mm thick and up to 2,250mm wide.

Hot strip mill

See reversing mill.

Hot-dip galvanizing
Hydroforming

This is a way of producing fully formed steel parts by using internal hydraulic pressure within a tubular blank to achieve the desired final shape.

Its attractions are that complex parts, often requiring quite significant deformation, can be produced simply from a single piece of steel, rather than from multiple pieces which then have to be welded together. Also, production from a single workpiece means the required mechanical performance can be achieved with thinner steel.

The most common applications are in the automotive sector where hydroforming is used to shape tubular parts into important structural components like engine support cradles, suspension parts, impact beams and some bodywork items.

Production involves placing the tubular steel feedstock into a die and then subjecting it to internal pressure to force the steel into the shape of the die that encloses it.

Several steelmakers are involved in hydroforming as part of their bid to get closer to their automotive customers. Some produce the tubular blanks used to form specific parts, while others are actually producing finished components.

I-beams
Idling

Idling is a temporary cessation of production with the inactive plant maintained in good order in readiness for a quick restart. It is distinct from planned maintenance shutdowns.

See also mothballing and shuttering.

Incoterms

International commercial terms (Incoterms) are standard trading definitions which are widely used in commercial transactions to clearly apportion costs, responsibilities and risks between buyer and seller. They were devised by the International Chamber of Commerce (ICC), and first appeared in 1936.

In international trade, language differences can very easily lead to misunderstandings in contract terms, in conditions and in definitions, hence the need for clearly defined commercial terms which mean the same to everyone wherever they operate.

Included in the Incoterms vocabulary are terms like FOB (free on board) and CFR (cost and freight) – see separate entries.

The ICC says that correct use of Incoterms goes a long way towards providing the legal certainty upon which mutual confidence between business partners must be based. The latest edition is “Incoterms 2000", published on 1 January 2000.

Induction Furnace

Unlike the electric arc furnace (EAF) which provides heat energy via electrodes submerged within the furnace charge, induction furnaces heat the charge indirectly.

An alternating electrical current is passed through a coil surrounding the refractory-lined furnace vessel. This creates magnetic fields which cause electrical currents (eddy currents) in the iron/steel scrap charge, heating and melting it. Once the charge is in a molten state the eddy currents generate a stirring action.

The capital cost of the induction furnace is lower than the EAF, it uses less power per tonne melted and there are no recurring electrode costs. However there is a size constraint. They typically range from 5-100t capacity for steel melting, but most operating units are towards the lower end. This makes them smaller than most EAFs.

Induction furnaces are mainly used by foundries, except in India where they also account for several million tonnes/year of mainstream steel production.

Although cleaner than the cupola furnace, which is also popular with foundries, the induction furnace does require a reliable electricity supply.

Indurating furnace

These furnaces form a key part of one of the process routes for preparing iron ore fines for use in blast furnaces, and are specifically used when iron ore pellets are being produced.
Raw or “green” pellets need to be baked to give them sufficient mechanical strength to withstand further handling during transportation and charging to a blast furnace or to a direct reduced iron furnace.
In an indurating furnace, the pellets are loaded on to a travelling grate to a depth of approximately 30-60cm where they are preheated (typically to 800-9000C), before entering a higher temperature stage (around 1,200-1,3500C) which in some designs is a continuation of the travelling grate, and in others take the form of a rotary kiln. Once hardened the pellets are cooled ready for use.
The other route to preparing iron ore fines is to agglomerate them by sintering with coke and limestone.

Ingot casting

Liquid steel cast in a mould into an unwrought mass. Now largely superseded by continuous casting.

Integrated steel mill

A steelworks which operates the complete cycle of production processes – taking in iron ore, coal and other raw materials, and delivering finished steel products.

Interstitial-free steel

This is flat-rolled steel which is completely deoxidised and with very low carbon content. It has very good deep drawing characteristics, and as such is widely used in the automotive industry for body panels and similar highly formed pressed components.
The interstitial-free (IF) description relates to the fixing of dissolved nitrogen and carbon atoms in the metals structure by micro-alloying during production using titanium or niobium. The removal of these solutes improves the steel’s formability.
Optimum properties are achieved through careful control of steel chemistry during melting, and subsequent close control of casting, rolling, and annealing operations.

Iron & Steel

Iron is a naturally occurring element which was first smelted from its ore into a tough silvery/white metal about 2,400 BC. Cast iron is hard and brittle, while wrought iron is soft and malleable. Iron from a blast furnace (pig iron) is an alloy of iron and carbon (about 4%), along with smaller quantities of silicon, manganese, phosphorus, sulphur and other elements.

Iron is a far less versatile metal than steel, which is also an alloy of iron. It is produced in a BOF and has a much reduced carbon content. Other elements, particularly manganese, are adjusted or added to achieve specific properties. There are many thousand different steel grades. Even high carbon steels contain no more than about 1.5% carbon, though some high alloy steels reach 2.5%. Carbon allows hardening of the steel via heat treatment.

Iron ore

This is found in commercial quantities in various parts of the world, the largest and best deposits being in Brazil and Australia. Ore can have up to around 65% ferrous (iron) content, but often it is lower and can be less than half this. Lower grades need to be concentrated (beneficiated) prior to shipment. (See also: hematite and iron ore pricing)

Iron ore pricing

Internationally-traded iron ore is priced in US cents per unit of iron contained in a ton of ore. The usual measure is a dry metric tonne unit (excluding moisture content), although dry long ton units are sometimes used.

A unit of iron is 1% of iron, and a typical current price is 75 cents per dry metric tonne unit (see Dry metric tonne unit). So, at this price for ore assaying 63% iron, a tonne sells for $0.75x63 = US$47.25 (excluding freight).

Iron ore types differ, so there is a wide range of prices to account for varying physical and chemical properties, including the presence of deleterious matter such as silica and sulphur. Lump ore and pelletized ore – which can be charged directly into the blast furnace – attract a premium over fine ore which needs pre-processing (usually sintering).

The Steel Index provides a weekly, independent iron ore reference price. Get a free trial at www.thesteelindex.com.

Joint Implementation (JI)
Joint Implementation is the mechanism under the UN Framework Convention on Climate Change by which developed (Annex 1) countries can invest in emissions reduction projects in other developed countries. Each project is awarded with a number of Emission Reduction Units equal to the amount of emissions saved.
Jumbo sections

These are extra large H-profile structural steel sections. They are specified where there is a need for exceptional strength or load bearing capability in buildings and other structures.

When used for horizontal load bearing they are referred to as jumbo beams, and as jumbo columns when applied in vertical load bearing duties.

Jumbo sections are rolled from blooms or beam blanks in a beam mill, and typically have a web depth of 500mm or more.

Killed steel

This is steel that has been treated with a deoxidising agent such as aluminium or silicon while molten and prior to casting. The aim is to significantly lower or totally remove the steel’s oxygen content so that there is no gas formed during subsequent solidification.

The resulting cast steel is non-porous and very homogeneous, and as either a flat or long product can undergo significant forming or drawing during subsequent processing.

Ladle metallurgy
Lance

In steelmaking, lances are hollow steel bars which can resist very high temperatures. They are used to introduce additional elements into the melting vessel after it has been charged with its principal raw materials (molten iron and scrap for basic oxygen steelmaking, and scrap and/or direct reduced iron and/or cold pig iron in electric arc furnaces).

In both types of steelmaking a lance is principally used to inject oxygen into the melt. This is essential in BOF steelmaking to achieve the chemical conversion of iron into steel, whereas in EAFs, oxygen injection is more usually associated with generating additional energy in the melt to reduce electricity consumption.

In EAFs, lances are also used to inject fossil fuels such as coal/coke for slag control.

Oxygen injection via lances is also an essential feature of several secondary metallurgy (steel refining) techniques.

Landed price equivalent

This is basically a freight cost adjustment on a delivered commodity price.

In the steel industry the term came to prominence via iron ore miner BHP Billiton, which successfully argued that delivered prices for Australian ore into Asian ports should reflect buyers’ willingness also to source ore from further afield (Brazil) and pay the correspondingly higher freight element in those landed ore costs.

 

Laycan

This is an abbreviation of ‘laydays and cancelling date’, and refers to the earliest and latest dates between which a vessel must be available to load at a specified port or be delivered to the time charterer.

LD process

See BOF.

Leaded steel

Lead is added to steel to enhance its machinability, and is a key feature of premium low-carbon free-cutting (free-machining) steels.

Lead’s much lower melting point and the fact that it is insoluble in steel, means that during machining it melts and forms a lubricating layer at the point of contact between machining tool and the steel being turned, milled or drilled. This lubrication allows faster machining through higher rotational and material feed speeds, and enhances cutting tool life. The lead in the steel also helps reduce deformation stresses.

Some free-machining steels contain bismuth or tellurium as a substitute for lead, but leaded steels are still regarded as the superior product. Their importance to the engineering industry is recognised by the European Union, which exempts leaded steels from its restriction of hazardous substances directive provided the lead content is no more than 0.35%. However, leaded steel swarf or turnings do require more specialised and more costly disposal. (See also, free-cutting steel.)

Levelling

This is usually the final stage in the preparation of cold reduced steel strip or coil prior to its delivery/use.

The role of a leveller is to correct shape defects in the strip, such as edge wave and centre buckle, and make the delivered product as flat as possible.

There are two principal types of levelling machine: roller levellers (or multi-roll levellers) and tension levellers.

In the former, the strip is flattened by bending it up and down as it passes over and under a set of as many as 20 or so small diameter rolls. In contrast, tension levellers use a combination of bending over fewer small diameter rolls while applying significant longitudinal tension to the strip.

As these two types of levelling are best suited to treating different strip defects, it is not unusual for them to be used in tandem.

Light sections

Small-sized structural steel sections (usually < 80-100mm).

Lightweight tonnes (lwt)

Lightweight tonnes (lwt) are a measure of a vessel’s actual weight with no cargo, crew, passengers or fuel (equivalent to the weight of water displaced), and are mostly used when selling a ship for scrap. See also gross tonnes, deadweight tonnes and compensated gross tonnes.

Limestone

Limestone is a key ingredient in blast furnace ironmaking along with iron ore and coke.

While the role of iron ore is to provide the metallic input and coke the process heat and reducing gases while also playing a structural role within the furnace, limestone is there to react with impurities introduced by the other two ingredients to form a slag which can be removed from the furnace without contaminating the iron.

The heat inside the blast furnace (up to 1,800oC) converts limestone into calcium oxide and CO2 gas. Calcium oxide readily reacts with impurities like silica, sulphur, alumina and magnesia to form a slag. This percolates down through the furnace to settle on top of the liquid iron where it can be tapped off.

The limestone used for ironmaking may be pure calcium limestone or dolomite (containing some magnesia), or a blend of the two. It is crushed and screened to approximately 10-35mm and charged to the furnace at a rate of approximately 250kg/tonne of liquid iron.

Depending on its composition blast furnace slag can be used in road construction and cement production.

Limited recourse financing
Linepipe

This is large diameter steel pipe, typically upwards of 300 mm, which is used to transfer large volumes of crude oil, natural gas, water and other fluids. Most is of welded construction, but some is seamless.
Crude oil pipelines are generally of smaller diameter, have thinner walls and use steel of lower grade than natural gas lines. This is due to the lower density of gas and the higher operating pressures used to achieve efficient transmission.

A workhorse grade of steel for oil pipelines is API X65, and diameters are typically in the range 300-800 mm, but can be higher.

Overland natural gas pipelines typically use grades like API X70 and X80, and are usually of 800-1,420 mm diameter. Subsea sections can require higher grades and diameters tend to be smaller than for onshore sections, typically 800-900mm, although wall thicknesses can be higher.

Liquidity

In the context of metals and other commodities, a market has liquidity if there is sufficient material available for trading, and enough buyers and sellers interested in trading, for individual lots to be bought and sold quickly and without individually causing a significant movement in the price of the commodity.

The greater the number of active buyers and sellers, the more liquid the market.

London Metal Exchange

The London Metal Exchange (LME) offers futures and options contracts for non-ferrous metals, steel and plastics. It was established in London over 130 years ago, and until recently only traded in non-ferrous metals.


The exchange provides a transparent forum for establishing prices on the day of trading (cash) and for hedging prices months and even years forward.


With its longer established contracts – like copper, aluminium, nickel, lead, zinc and tin – LME prices are used as a reference worldwide. Its steel billet contracts were launched in 2008.


Being a principal-to-principal market, only member firms are able to trade. They provide the physical industry with access to the market, to the risk management tools and to the delivery mechanism.


Trading takes place via open-outcry trading on the floor of the exchange, through an inter-office telephone market and through the LME’s electronic trading platform.


LME approved warehouses around the world provide a point of delivery of last resort or source of metal in extremes of market supply and demand.

Long products

Steel products other than flat products. Includes bar, rod, beams and rail.

Lump ore

This is one of the three forms in which iron ore is purchased by integrated steel mills (the other two being fines and pellets). It is generally in the size range 10-40mm and commands a price premium over fines (which need to be sintered into a lumpy charge for use in the blast furnace), but lump ore is cheaper than pellets.

Magnetite

This iron oxide is one of the two principal types of iron ore used in iron making (the other is haematite/hematite). Most of the very large reserves of this ore occur in banded iron formations, much of which can be surface mined. But magnetite (Fe3O4) also occurs as black beach sands, of which those found in New Zealand are typical.

Malleability

A steel which is malleable can be deformed by compressive forces without cracking or rupturing during its working into a new shape by rolling, forging, hammering etc.

Forging steels should be able to tolerate sudden impacts without rupture, while steels which are tolerant of more gradual compressive changes can successfully be rolled into thinner gauges or smaller diameters.

Malleability, or the lack of it, is one of the key properties used in describing the physical characteristics of a metal. The others include toughness, hardness, ductility and strength.

Manganese

This is the most widely used alloying addition in steelmaking, and is present in virtually every grade of steel.

Manganese (Mn) has three key benefits. It combines with sulphur in the melt to improve the hot working properties of the resulting steel, it acts as a deoxidant, and it makes an important contribution to the final toughness and hardness of the steel.

It is mostly added as ferro-manganese (FeMn), but can be added as silico-manganese (SiMn) depending on the final steel grade required.

FeMn is produced from manganese ore or concentrate mostly in electric arc furnaces, and is generally categorised as high, medium or low carbon material. In commercially traded grades the Mn content is often in the range 75-80%, though it can be 65-82%. Carbon content is usually in the range 1.5-7.5%.

Manganese can also be added to the melt in the form of spiegeleisen – pig iron with a high manganese content.

Martensitic steel
Mechanical tube
Medium sections

Medium-size structural steel sections (usually 100-400mm).

Meltshop

This is a commonly used term which describes the part of a steelworks which is involved in melting, refining and casting steel.
It is particularly associated with electric arc furnace based steelworks, where the production of steel from scrap and other metallics, its subsequent refining and then its casting usually all take place under one roof.
The key equipment embraced by this term are the electric arc furnace, the ladle furnace (for refining the liquid steel), and the continuous casting machine (for producing long or flat semi-finished products for rolling).
Meltshop is a less appropriate description for the liquid metal activities of an integrated steelworks, where molten iron is produced in a blast furnace, sent to a converter shop elsewhere on site (to be converted into steel), and then transferred to a continuous caster.

Merchant Bar

Merchant bar is a range of commodity carbon steel long products widely used in the manufacture and fabrication of a broad range of items. It includes round, square and hexagonal bars, angles, channels and flats. Maximum diameter or width is usually 80-100mm, although flats up to 150mm wide are included. These are a staple item for many steel stockholders, large or small.

Merchant pig iron

Most pig iron is produced in blast furnaces for subsequent steelmaking at integrated steelworks, and is transferred as molten iron from BF to nearby oxygen converters.

But a much smaller tonnage is produced for sale as a steelmaking or foundry raw material. This merchant pig iron is mostly made in coke or charcoal fuelled BFs and sold as ingot. Electric arc furnace (EAF) steelmaking, rather than foundry castings, is the main application. Some integrated steel mills also sell surplus pig iron.

Total global merchant trade is around 25m tonnes/year, with some 17m t/y internationally traded, according to International Pig Iron Association data. The figures exclude China, which has a very large, but difficult to quantify, domestic market, and is an occasional exporter.

Pig iron is a supplement to ferrous scrap in the EAF, and may be used instead of, or in addition to direct reduced iron or hot briquetted iron in order to make higher grades of steel that may not be achievable using only scrap.

Mesh

Steel rods or bars welded into an open lattice for reinforcing flat concrete structures.

Metallurgical coal
Mill scale

Mill scale forms on the surface of steel when oxygen reacts with very hot metal to form iron oxides. This occurs immediately after casting, and during reheating and hot rolling.

The scale, which can range in size from a few microns to several centimetres across, has to be removed, otherwise it will damage the surface finish of the steel during any subsequent rolling. High pressure water jets are used to blast away the scale, and on a hot strip mill this occurs as the steel passes down the run-out table from the roughing mill.

Some mills, particularly plate mills, also offer customers the option of having any residual mill scale removed by shot blasting.

In integrated steel mills this iron-rich scale can be recycled by returning it to the sinter plant. However, contamination of the scale with oils and hydraulic fluids during its collection can restrict reuse for technical and environmental reasons.

Mill stand

See reversing mills.

Mineral resources and reserves

A resource is an occurrence of minerals that is believed to have the potential to be technically and economically extracted. The degree of confidence that is held in the estimated quantity, quality and mineability of the minerals is reflected in the different categories assigned to resources – namely ‘inferred’ (the least certain), ‘indicated and ‘measured’ (the clearest indication of expected grade and tonnage).

A mineral reserve is part of a resource that more detailed geological and metallurgical evaluation has shown to be economically mineable. The degree of certainty in this evaluation is given by the categorisation of reserves as either ‘probable’ or ‘proven’.

Mini Mills

 Although this term is becoming less widely used, it refers to scrap-based steelworks, usually producing mainstream/commodity products, which are mainly sold into local/regional markets.

Mini-mills first flourished in northern Italy and the USA from the mid-1960s as basic, privately owned, non-unionised, entrepreneurial operations producing long products. They capitalised on the increased volumes of scrap that were becoming available as open hearth steelmaking gave way to BOFs, a low cost base and their proximity to local markets.

Minis have grown in scope, scale and geographical presence, often dominating long products supply in the regions where they operate. They have become increasing active in making more demanding grades/shapes/sizes of longs, and moved into flat products, including galvanized and plate

The most stunning example of mini-mill evolution is Nucor, which is now one of the largest producers of steel in the USA.

Molybdenum

In steelmaking this high melting point metal is used as an alloying element in engineering and stainless steels. It improves corrosion resistance and hardenability, enables steel to perform at elevated temperatures – and confers higher strength at these temperatures – and improves weldability.

In stainless steels the highest content is about 6%, but the most widely used moly-containing grade of stainless (austenitic 316 / 1.4401) has 2.5-3% Mo.

In other alloy steels the moly content is usually below 1%, but there can be as much as 9-10% in high speed steels.

Molybdenum containing steels are used to meet demanding in-service duties in a wide range of applications – from mining and power generation, to the automotive, aerospace, process and oil/gas sectors.

Mothballing

This is the long term closure of a facility, but with it decommissioned and subsequently maintained in such a way that it can be brought back into service if required – although this would take longer than if the plant were idled.

See also idling and shuttering.

Nameplate capacity
New production scrap

See scrap.

Nickel

This silvery-white metal with a high melting point (1,454oC) has corrosion resistant properties and is workable, despite being hard with good strength and toughness.

Nickel is an important constituent of stainless steel, and increases the tensile strength of carbon steel. It is also essential to some other alloys capable of operating at very high temperatures and/or in very aggressive environments. Electro-plating, portable batteries and coinage are other applications.

Canada, Russia and the Pacific rim, particularly New Caledonia, are the major producers.

Stainless steel accounts for 60-65% of global consumption (~1.2m t/y), and collectively, metallurgical applications take over 90% of nickel demand.

In stainless steel, nickel is most associated with austenitic grades (typically 4-22% Ni). It is sometimes present in ferritic and martensitic grades, but at low concentrations. In duplex grades the Ni content can be up to about 7%.

The LME is the basis of nickel pricing (as refined cathode, 99.8% Ni).

The metal can be added to the stainless steel making process as cathode, cut cathode, ferro-nickel (~30-35% Ni) or nickel pig iron. Stainless scrap is also an important source.

Nickel pig iron

This is a low purity ferro-nickel which is produced and used exclusively in China as an alternative to primary nickel or conventional ferro-nickel in the stainless steel industry. Much of it goes into the production of the low-nickel, high-manganese content 200 series stainless.

Small blast furnaces, and increasingly electric arc furnaces (EAFs), smelt low grade lateritic (oxide) nickel ores imported from Southeast Asia, to make a product with a nickel content ranging from as low as 1.5% to up to 25% or more. Conventional FeNi typically contains around 40% Ni. The higher grade nickel pig iron mostly comes from EAF producers.

Production economics are highly dependent on world primary nickel prices, as well as on coke and electricity costs.

Other constituents in nickel pig iron are small amounts of chromium, sulphur and silica, and unwelcome levels of phosphorus and carbon – which need to be lowered. Iron accounts for the balance, and can add significantly to the value of the product, as can chromium, depending on their prevailing market prices.

Non-prime

This term embraces a range of material, but mostly it is steel which is unsuitable for its originally intended application – either because of its metallurgy or physical condition – or is in excess of the tonnage required to fulfil a particular contract (over-rolled).

Much non-prime is the result of defects created during steelmaking and downstream processing – and as a result this steel does not have the mill certification associated with prime material.

Additionally, a mill may deliver what it believes to be prime steel only to have it rejected on arrival – so called ‘field rejects’ – usually because of visible defects caused by improper handling or incorrect presentation.

Also, some steel comes on to the market because it is surplus to a specific project or production run, or is simply the result of a purchasing error.

Non-recourse financing

This is financing where the lender is only entitled to repayment from the revenue or profits of the project/activity that the loan is funding, and not from any other assets of the borrower. This is in contrast to full-recourse financing, where the borrower fully guarantees the debt, and repayment is not in any way conditional on revenue from the activity being funded.

Between the two, and with similarities to non-recourse financing, is limited-recourse financing. Here the majority of loan repayment comes from project/activity revenue, but the lender also seeks other assurances of repayment from sponsors, contractors, raw materials suppliers, governments etc, as well as guarantees of cash flow – such as by a project securing advance sales contracts. A common option in regions where financial risks are higher.

Normalising

This is a process similar to annealing, where metal is heated to a high temperature and held at this temperature for several hours to improve grain structure. But unlike with annealing, where the metal is cooled slowly in the furnace, it is cooled more swiftly by removing it from the furnace to cool in air.

This makes the metal stronger and harder than it would be after annealing, and because of this the normalising process is often employed to treat steel plate used for pressure vessel fabrication.

Steel casting, forging and rolling are both processes that might produce grain structures in the metal that require normalising before it is used or further processed.

Obsolete scrap

See scrap.

OCTG

This is shorthand for Oil Country Tubular Goods, a category of steel tube used in oil and gas drilling and extraction. Much of it is seamless, but welded tube is also very prominent.

OCTG comes in three forms, drill pipe, casing and oil well tubing. It does not include pipe for conveying oil/gas from the point of production to the refinery or customer; this is linepipe. Drill pipe connects the drill bit with the drilling motor during well drilling and is usually about 2-6.5in (50-165mm) outside dia. Drilling mud is pumped down the pipe to cool the drill bit, while drilled material travels up it to the surface. The very demanding operational conditions mean drill pipe is always seamless.

Casing acts as the liner and structural wall of oil/gas wells, preventing contamination of the well and of the surrounding water table, and can be up to 26in dia. Casing accounts for about three quarters of all OCTG shipments. The third type is oil well tubing. This is used to bring oil/gas out of a well and is usually around 2-4.5in dia.

Oil well tubing

See OCTG.

Open hearth steelmaking

Open hearth steelmaking has largely been superseded by basic oxygen, and in some instances by electric arc furnaces (BOFs and EAFs), and today accounts for less than 3% of world crude steel output. Where plants still exist – notably in Russia and Ukraine, but also India – they are mostly being phased out.

When introduced in the mid-19th century, open hearth (OH) steelmaking offered the potential to make higher quality steels than existing processes (mostly the Bessemer converter). The process could also accept a high proportion of ferrous scrap at a time when this was becoming plentiful in newly industrialising countries.

Steelmaking takes place in a shallow bath – typically of about 500 tonnes capacity – within a refractory-lined chamber. Heat energy is usually supplied by the combustion of preheated gas and air above the bath surface. The charge of cold and/or molten pig iron and scrap can be supplemented with iron ore and limestone.

It takes several hours to produce each batch of steel, so OH steelmaking is far less efficient that the BOF (and EAF) routes. It is also both more labour intensive and more polluting.

Open outcry

This is a style of trading which is used in several commodity and futures exchanges, although electronic trading is tending to gradually erode the extent of its use.
During an open outcry trading session a broker announces verbally and by hand signals his/her interest in buying or selling a commodity and gives the price and required date for delivery. Should another broker in the ring accept these terms, the price quoted becomes the latest price for the delivery date specified.
Trading in ‘the ring’ at the London Metal Exchange is one example of an exchange using the method, and the New York Mercantile Exchange and Chicago Mercantile Exchange are two others.
In most exchanges using open outcry the trading floor is call ‘the pit’.

Ore

A mixture of valuable minerals and gangue from which at least one of the minerals can be profitably extracted.

OTC (over-the-counter) trading

In the context of metals trading, OTC (over-the-counter) trading refers to an agreed forward trading position between trader and client that is not a standard contract in the sense that it is not arranged and transacted on a commodities exchange such as the London Metal Exchange.

OTC contracts are established between traders or brokers and their clients over the telephone or electronically, rather than on the trading floor.

A key attraction of these contracts compared to futures contracts is their flexibility. An OTC contact can be for a grade or quantity of metal mutually agreed with the broker, while exchange-listed futures have to be traded for the specifications detailed in the futures contract and can only be traded in multiples of the fixed lots sizes of the contract.

OTC also allows trading of exchange listed products to continue outside of exchange opening hours.

This form of transaction is also very useful for brokers and traders who are too small to meet the requirements to trade an exchange listed future, or elect not to do so.

Outsell prices

These are the prices at which stockholders and service centres sell steel to their customers. In normal market conditions the outsell price is higher than the price at which the steel was bought by the stockist from a mill, trader or other supplier because of the cost incurred in breaking large mill-size orders into much smaller consignments.

Over-rolled
Oxidizing atmosphere

An oxidising atmosphere contains sufficient oxygen for this to combine with (oxidise) certain other elements if they are present. An everyday example is the rusting of steel, which is essentially the oxidation of the metal in the presence of moisture to form a surface layer of iron oxide.
An oxidising atmosphere is key to the success of the basic oxygen steelmaking process for converting liquid pig iron into steel. Oxygen is blown through the molten iron in the BOF vessel, where it combines with and removes unwanted carbon as carbon monoxide and carbon dioxide.

PCI (pulverised coal injection)

This is principally a cost reducing technique in ironmaking. It involves substituting part of the normal coke charge to a blast furnace with coal that is cheaper than the hard coking variety needed for coke making. PCI also reduces environmental impact because less cokemaking capacity is required.

The low-volatile coal used for PCI can typically be 20% cheaper than coking coal. Also pulverisation is less capital intensive than coke making.

Coal is prepared by pulverising it into very small particles before injection into the furnace, typically at rates of 120-150kg per tonne of liquid iron production. This is about one third of the normal coke requirement of a blast furnace operating without PCI.

PCI Coal

The coals used by steelmakers for pulverised coal injection (PCI) into blast furnaces are broadly speaking steam coals (which are mostly used by coal-fired power stations) rather than the coking coals used to produce coke.

The desirable qualities in a PCI coal relate both to its thermal performance in the furnace, and to its physical characteristics (which vary depending on the individual coal preparation, handling and injection techniques used).

Coal with a low phosphorus, low sulphur and low ash content is sought, and other key qualities are a good calorific value and good combustibility. As already indicated, coking qualities are not required.

High volatility coals are desirable for their ready combustibility, but high volatility is not synonymous with a high calorific value (which increases the coke replacement rate that can be achieved), so there has to be something of a compromise here.

The behaviour of ash, char and any remnant coal particles in the furnace is also an important consideration when selecting coals for PCI.

Peeled bar
Pellet

A small, round, marble-sized ball of iron ore manufactured as feed for blast furnaces (see pelletizing).

Pelletizing

The process by which iron ore is crushed, ground into a powder, rolled into balls and fired in a furnace to produce strong, marble-sized pellets that contain 60% to 65% iron. Raw iron ore pellets are generally manufactured within certain size categories and with mechanical properties high enough to maintain usefulness during the stresses of transference, transport, and use. Both mechanical force and thermal processes are used to produce the correct pellet properties.

Pickled & Oiled

Pickling is a continuous operation that requires the decoiling and subsequent recoiling of the HRC so that it can pass through the acid-based liquid pickling process. This cleans the steel, removing surface scale, rust and dirt or grease, before rinsing and drying.

Applying a surface oil film after pickling helps protect the steel from corrosion and assists further processing operations, such as press-forming, by providing lubrication to the die.

Pig iron

See iron & steel.

Piling
Pipe

See welded and seamless tube/pipe.

Plate

Plate is thick, flat-rolled steel produced from slab or ingot, and is mostly sold as discrete pieces but also coiled. It is available in carbon, alloy and stainless grades.

The majority of the plate produced is in the thickness range 5-80mm and overlaps with hot rolled coil at the lower gauges.

Most carbon plate is quarto or discrete plate rolled on reversing mills, but a minority is produced on hot strip mills as coiled, or continuously produced plate.

Quarto plate (see separate entry) can be over 5 metres wide and up to 400mm thick. Coiled plate is normally up to about 12-14mm thick and mostly less than 2 metres wide.

Much plate is produced to specific customer requirements, and this greatly reduces the size of the freely traded plate market.

Most commodity trade is in 8-50mm thick material, and two popular European grades are S235 and S355. Main applications include heavy machine building, various civil, industrial and offshore structural applications, wind turbine towers and off-road equipment.

Ship plate spans the gap between commodity and the higher grades specified for boilers and pressure vessels, large diameter oil/gas pipe and other energy sector uses, including some offshore.

Position limit

A limit set by an exchange on the number of options or futures contracts one trader, or a group of traders, can hold on the same side of a commodity market.
The aim is to ensure stable market conditions by preventing control and manipulation of the market by one or a small group of traders.
Exchanges set position limits for contracts bearing in mind prevailing trading volumes.

Powder metals

These are metals that have been converted into fine powders for subsequent processing into finished parts.
The powder is most typically produced by atomisation, whereby a steam of molten metal is separated into very small particles by a high pressure jet of gas or liquid, with the particles solidifying before they are collected. Electrolytic, chemical and mechanical methods are also used.
Ferrous and non-ferrous powder metals are employed to make both large and small complex components with good dimensional accuracy and a homogenous structure. This is often done by compacting powder in a die before sintering (heating) at just below the metal’s melting point. Other methods include injection moulding and forging.

Pre-feasibility study

A preliminary assessment of the economic viability of a deposit which forms the basis for jusifying a more extensive and expensive feasibility study.

Precipitation hardening

This is a heat treatment technique which is used on some grades of stainless steel, as well as certain non-ferrous metals like aluminium, nickel and titanium.

Its purpose is to significantly raise the strength and hardness of the metal, but the downside of using the process is a reduction in ductility.

The metal being treated has to be held at elevated temperatures for longer than is the case with tempering*, and because of this extended time period – which can be several days – the process is sometimes described as age hardening.

At the end of the heating period the metal is cooled using air, oil or water.

Price-fix hedge

This is an instrument that enables the hedger – often a miner or end user of metals – to lock in a future price for a commodity for an extended forward period, sometimes up to several years ahead.

Profile
Prompt scrap

See scrap.

Pulverized coal injection

See PCI.

Quarto Plate

Quarto plate is hot rolled from slab. Desired thickness is achieved by passing the slab back and forth through the mill (a 4-high, hence “quarto”, reversing mill). This distinguishes it from plate rolled on a multiple stand (tandem) mill without reversing direction (continuously produced plate, CPP).
 
 Quarto plate mills tend to be dedicated to plate rolling, and can achieve a wider, thicker product than on a tandem mill. It ranges from 5-400mm thick (though usually up to 150mm), can exceed 5,000mm wide and be as much as 35m long. A single quarto plate can weigh 35t or more.
 
 Depending on steel grade – and the term applies to carbon, alloy and stainless – applications include shipbuilding, pressure vessels/boilers, offshore structures, large oil/gas pipe, construction/mining plant, railway stock, and engineering moulds/dies.

Quenched and tempered steel

This is a complex process to describe fully because it involves fundamental changes to metallurgical structure. But in outline, pre-heated steel is rapidly cooled (quenched), increasing its hardness and brittleness. It is then reheated (usually to between 400-600C) resulting in reduced brittleness but greater toughness and the desired ductility.

Control of time and temperature during tempering is critical, and is specific to each grade of steel treated.

Quenching and tempering is used both on flat and long products. It is, for example, applied to bar used for manufacturing fasteners like bolts, or when making wire for automotive engine valve springs. In flat products, the high strength structural and wear resistance plate achievable with this process would typically go into mining equipment.

Quenching

See quenched and tempered.

Re-rollable scrap

This is steel scrap which is in such a form and condition for it to be possible to make it suitable for another application by rolling into a saleable product, rather than it taking the normal scrap recycling route of melting, casting and rolling.
Re-rolling is a production route which is more prevalent in emerging economies than in industrialised countries, and a wide range of steel sizes and shapes are traded in this sector, including plate, bar, rebar, sections and profiles, as well as specific items like steel rails and railcar axles.
Demolition scrap is a principal source of re-rollable steel, but in the Indian subcontinent another major supply of such material comes from the ship breaking industry.

Real consumption
Rebar (reinforcing bar)

A steel bar, normally having surface deformations, for use in reinforcing concrete.

Rectangular hollow sections

Rectangular hollow sections (RHS) are tubular products rolled from steel strip. They are made by first forming the strip into a longitudinally welded tube before rolling through further mill stands to change the shape to a rectangular, rather than circular, cross-section.

 

Also generically known as hollow structural sections (HSS), they are often also made with a square cross-section.

 

Rectangular hollow sections are predominantly, though not exclusively made from carbon steels, and are usually cold formed, rather than rolled with the steel pre-heated (hot formed).

 

A typical size range for cold formed RHS is 50-450mm x 25-250mm, with a steel thickness of 2-15mm.

Hot formed RHS can be produced with larger sections and with a greater steel thickness. RHS have a wide range of mechanical and structural applications in the engineering and construction sectors.

Reducing atmosphere

In a reducing atmosphere, oxidation is prevented because there is little or no oxygen, or other oxidising gases present. Hydrogen is a typical reducing atmosphere.

Refining
Refractories

These are used to line and insulate the vessels involved in iron and steel making (blast furnaces, torpedo cars, basic oxygen converters, ladle furnaces, tundishes) as well as the various heating furnaces used to ensure cast steel is at the correct temperature for hot rolling.

They are often made of magnesite in combination with alumina, dolomite, silica and sometimes carbon. They are mostly used as bricks, but refractory material can be applied directly to form a lining.

Refractories need to be resistant to high temperatures (up to more than 1,500 degrees C) and be strong at these temperatures. Those used in hot metal production must not contaminate the melt and must be resistant to erosion by molten metal, slag and fluxes.

However refractories do gradually degrade, and although minor defects can be repaired in situ, eventually a full or partial reline is needed. In the case of a blast furnace this may be every 10-15 years, but is more frequent with other equipment which can more readily be taken offline for short periods.

Reheat furnace

Reheat furnaces are used to ensure that partly worked steel, which has been allowed to cool, arrives at its next processing stage at the optimum temperature. They are mostly used for semi-finished items like slabs, blooms, billets and beam blanks, but also tubes.

There are several different configurations, notably walking beam, walking hearth, pusher and rotary hearth. Such furnaces are usually gas or oil fired, and during its residence time the steel goes through three stages: preheating, heating and soaking.

In walking beam and walking hearth furnaces the steel is moved through the furnace in a series of lifting/forward movements. With pusher furnaces, each piece of steel pushes the one in front, propelled by a pusher arm at the entrance. With the rotary hearth, the steel reaches its process temperature after one revolution on the horizontal hearth, and this type of furnace is also frequently used for forgings and for the heat treatment of rolled steel.

Reserves

See mineral resources and reserves.

Resource
Reversing, tandem & continuous mills

Steel is rolled to reduce its thickness (gauge) by passing it between a pair of rolls in a rolling mill (a mill stand).


But as it is rare to achieve the desired final thickness or cross-section in one step (single pass); the steel will need to go through the same mill several times (with a reduced roll gap, and/or changed roll profile each time), or transferred to other mill stands for further reduction/shaping.


When steel is rolled back-and-forth through the same mill, this is a reversing mill. When it moves directly in a continuous process to other mill stands, this is a tandem or continuous mill. These can achieve far higher throughputs than a reversing mill.


Tandem mills are associated with flat products and typically have 4 or 6 stands. Continuous mill is a long products term, and can be followed by an indication of the number of stands and product (eg. 8-stand bar mill, 10-stand rod mill etc).

Revert scrap

See scrap.

Rimmed steel

This type of steel is produced during ingot casting, with the resulting ingot having a very pure surface layer, or rim.

This feature is due to the absence or near absence of a deoxidising agent during steel production, which allows carbon monoxide to be formed from the oxygen and carbon in the melt. As this gas migrates to the surface, other elements (eg.carbon, phosphorus and sulphur) gravitate towards the centre of the ingot to leave a much purer layer or rim on the outside.

After hot rolling this steel has a good surface finish which is low in carbon. The overall carbon content of rimmed steel is usually below 0.25%.

Also known as drawing quality steel, it is usually used for cold processes such as forming, heading and bending.

Rod
Rolling mill

A machine which converts semi-finished steel (semis) into finished steel products by passing them through sets of rotating cylinders which squeeze the steel into the desired shape. Rolled steel products include bar, rod, plate, beams, coil etc.

Roughing mill

The principal function of these mills is to roll hot semis down to the correct entry dimensions for subsequent rolling stages, while removing as much surface scale as possible. These are reversing mills, ie the steel goes back-and-forth through the mill (multiple passes) until the desired dimensions are achieved.

SAW pipe

Both electric resistance welded (ERW) and submerged arc welded (SAW) tube or pipe is mostly produced by first forming steel sheet or plate into a cylinder and then welding the longitudinal gap to form a seam.

SAW is a form of electric arc welding. A power supply is used to strike an arc between a consumable electrode and the pipe. This heats the steel, and filler metal in the electrode melts and flows into the seam. Fluxes in the electrode blanket the welding operation, suppressing sparks, fumes and ultra-violet radiation.

SAW is mostly associated with larger, thicker-walled pipe manufacture.

See also ERW pipe.

SBQ

  SBQ, or special bar quality, is a predominantly North American term to describe steel long products for more demanding processing or end-use applications than can be met by commodity grades. Elsewhere the term “engineering steels” is widely used.

The chemistry and production routes for SBQ are more complex than for merchant bar and other commodity grades, and they are generally machined, forged or cold drawn during subsequent processing.

The main application area is the automotive industry for engine, transmission, steering and suspension components, but these steels find widespread applications from hand tools to electric motors and in the petrochemicals and other industrial sectors.

Scarfing
Scrap

All steel is 100% recyclable without loss of quality. Obsolete scrap is derived from steel-containing goods at the end of their useful lives (a drinks can, a 15-year-old car, a 50-year-old building). Revert scrap (home scrap) is steel waste produced and recycled within a steelworks. New production scrap (prompt scrap) is generated when steel is cut and formed during the manufacturing of finished products or components. The scrap is returned to steelworks and foundries. (see also: HMS 1 & HMS 2, and busheling). See also: re-rollable scrap.

Seamless tube/pipe

Seamless tubes have greater strength than welded tubes because of their homogenous microstructure, but are much more expensive to produce. They are made by rolling a preheated billet between offset rolls (the axes form an “x”) At high rolling speeds and pressures this configuration sets up stresses in the centre of the billet that facilitate its piercing with a pointed bar, or plug, to create a tube shell.

This shell is then elongated in a multi-stand rolling mill with a mandrel, or long bar with a shaped end, inserted inside the tube to achieve the desired wall thickness and a limited range of diameters.

Tube diameter can also be achieved with a sizing collar, but for significant diameter changes the tube is reheated and passed through a stretch-reducing mill – a multi-stand mill that reduces outside diameter but not wall thickness. Boiler tubing, the oil and gas industries, and automotive transmission components are typical applications.

Secondary metallurgy

Steel’s precise composition can vary from customer to customer, and steelmakers use a secondary metallurgy vessel (often referred to as a ladle furnace) between the steelmaking and casting operations to allow molten steel to be brought to the required specification.

Typically the composition, purity and temperature of the steel are adjusted at this intermediate stage by adding alloying elements or by more sophisticated treatments such as vacuum degassing. Key operations can include deoxidation, desulphurisation and dephosphorisation.

Not only does the use of secondary metallurgy enable a larger range of steel grades to be cast, but fine tuning steel composition in a separate furnace greatly improves the productivity of the main steelmaking unit. This is because with metallurgical adjustments taking place elsewhere, the time from steelmaking raw materials in, to tapped liquid steel out, is shortened.

Secondary refining
Sections
Semi-finishing mill
Semis

Semis is short for semi-finished steel, which is the name given to large, uniform cast pieces that require further processing in order to be transformed into finished long, flat and tubular steel products.

Most semis are continuously cast, and take the form of blooms and billets (for rolling into long products like bar and sections, or for making seamless tube) and slab (for rolling flat products like coil and sheet). But there are still a few mills without continuous casting and they cast ingots for subsequent processing. Also, some producers of certain alloy steels specifically cast ingots for metallurgical reasons.

All semis have to be hot worked in order to achieve the required dimensional changes. This is mostly by rolling, but can be by rolling/piercing (for tube) or by forging (for individual components).

Sendzimir mill

The Sendzimir mill is specifically designed for processing stainless steel and other metals which rapidly work harden during cold rolling, making gauge reduction difficult.

A typical Sendzimir rolling stand is immediately recognisable by its large number of small diameter back-up rolls (typically about 20) clustered around two small-diameter work rolls. This is in contrast to the large diameter work rolls and two or four large back-up rolls on most rolling mills.

The large number of back-up rolls on the Sendzimir allows very high reduction forces to be exerted on the passing sheet, and gauges down to 0.025mm are not unusual for stainless steel – although several passes through the mill may be required to achieve this. After each cold reduction, stainless coil must be annealed before it can be further processed.

The original design was developed the Polish engineer Tadeusz Sendzimir, but this type of mill is also referred to as a Z-mill or cluster mill, and apart from rolling stainless, is used for silicon and certain carbon steels, as well as some non-ferrous metals.

Service centre
Shale gas

This is a natural gas – mostly composed of methane – which is trapped within sedimentary geological formations known as shale (a fine grained, flaky deposit predominantly composed of clay). The gas is the result of the decomposition of organic matter within the shale bed.
Exploitation of this resource has been most rapid and most successful in the US, where it has significantly altered the economics of energy supply, but there are believed to be many other parts of the world where it could be economic to extract shale gas.
The gas is released using a process called hydraulic fracturing, where water and chemicals are pumped into the shale at high pressure to break up the formation and allow the gas to escape and be collected.
The main impact of the rise in shale gas extraction on steelmaking has been a revival of interest in gas-based production of direct reduced iron.

Sheared scrap

Shearing is used to cut large pieces of scrap into more manageable sizes, and is most frequently associated with the processing of heavy and demolition scrap. Shears are heavy duty static pieces of equipment.

Sheet pile

A sheet pile is a length of narrow, hot rolled strip, up to 20-25 metres long, which is given a profile either during hot rolling or through subsequent cold forming to enhance rigidity and provide an interlocking system along its edges.

Sheet piles are driven vertically into soft ground, and their edge profile allows each successive pile to interlock with the previous one to form a continuous retaining wall. The piles are typically 3-20mm thick and around 600-800mm wide.

Temporary applications include coffer dams used to retain ground or water during the preparation of building foundations or bridge piers. These piles can be removed and reused. Permanent applications include river and harbour walls, bridge abutments, and walls in basements and underground car parks.

Although sheet piling can provide a water barrier, it is not totally watertight.

Short ton

See Ton

Shot peening

This cold working process involves the bombardment of a metal surface with small spherical particles of steel, glass or ceramic in order to improve the in-service life of machined or fabricated components.
Each piece of shot, travelling at high velocity, acts as a miniature peening hammer as it hits the metal surface, forming a small indentation or dimple in the surface. The effect of this is to create a compressive layer at and near to the metal’s surface which serves to counteract any tensile forces set up in the component during manufacture, and makes the part less susceptible to fatigue or stress failures during service.
Although the process may resemble sand blasting, shot peening slightly deforms the metal’s surface, rather than abrading it.

Shredded scrap

Shredding transforms mixed metallic scrap into a more homogeneous product. It is done in a shredder, a powerful piece of enclosed equipment with rotating hammers which break down the incoming material. Shredded scrap’s regular consistency is attractive to electric arc furnace operators as it is easy to charge and offers uniform steel chemistry.

Shuttering

Shuttering means the permanent closure of a facility. The only way back for such units is through a subsequent sale to a new owner who is prepared to bring them back on line.

See also idling and mothballing.

Silicon

Silicon is one of the most abundant elements in the earth’s crust. As well as being used in carbon and stainless steel making in the form of ferro-silicon, it is the basis for most semiconductors, is used as silica in the production of glass and ceramics, and finds application as silicon metal in aluminium refining.

In steel refining, ferro-silicon (FeSi) acts as a deoxidiser to reduce carbon loss, but is also used to improve tensile strength and heat resisting qualities, and to enhance the magnetic properties of steels used in electrical equipment (see also electrical steels). In foundry iron production FeSi improves casting performance.

FeSi is produced from silica, coke and iron/scrap in electric furnaces, and is the most energy intensive of the bulk ferro-alloys to make.

The most widely used grades contain 75% silicon, although lower grades are traded. Small amounts of aluminium and calcium are also present, normally 1-2%.

Silicon steel

See electrical steel.

Sinter

This lumpy material is produced by integrated steelworks for use as a raw material in ironmaking, and is the main way of introducing iron ore into blast furnaces. Sinter is made by mixing iron ore fines, coke and a flux, such as limestone, placing this mixture on a steel conveyor belt, and igniting it. The resulting high temperature causes the constituents to fuse into a porous clinker but not to melt.

Iron ore fines are the principal iron source for steelmakers, but without such agglomeration they would be difficult to charge to the blast furnace and, in the large volumes required, would form a dense impermeable mass once inside the furnace, seriously affecting the efficiency of the ironmaking process.

Skelp

The steel strip feedstock used by welded tube/pipe mills. It is of the width required to give the correct tube diameter after forming by mill rolls either into a circular section for the longitudinal welding of its two edges, or into a spiral to produce a spirally welded pipe.

Skin pass mill

This is a specialised rolling mill which is used as a final stage in the processing of hot or cold reduced steel coil to enhance product quality.

Basically the steel coil is rolled not with the aim of achieving significant further reductions in gauge, but to give the sheet better and consistent mechanical and geometrical properties throughout its length – properties such as good elongation tolerance, flatness and surface finish. Gauge reduction is minimal.

The skin pass mill can be located as an in-line unit immediately following a hot or cold rolling line, or be a stand-alone facility. In the latter case the mill will have a decoiler on the entry side and a recoiler on the exit side.

Skin pass mills, which are also often referred to as temper mills, can be single or 2-stand units and have a 2-high or 4-high mill roll configuration. Mills with a 2-stand configuration are usually considered preferable when processing harder materials.

Slab

A semi-finished product (semi) of flat cross-section, but usually more than 200mm thick, used for rolling into a plate or coil.

Slabbing mill
Slag

Flux materials are charged into a furnace to remove impurities from the iron or steel as a slag. After solidifying the slag can be reclaimed for use as an aggregate or, in the case of high-phosphorus slag, a fertiliser

Slitting

See cutting-to-length.

Special bar quality

See SBQ.

Special steels

As opposed to ordinary mild or carbon steels, special steels are alloyed to achieve particular mechanical properties to suit specific end-uses. Examples include steels for cutting tools, roller bearings or springs. (see also: SBQ)

Spread

This is the difference in two prices, for example the contango or backwardation between two prompt dates, or the difference between the bid and offer price.

Spring steel

This steel will tolerate continual deflection under load, but recover to its original form once the loading is removed. It is a medium carbon steel (0.4-0.95%) available both as a long product (bar, wire) or in flat form. High yield strength is important and the key alloying additions used to determine the steel’s final properties are silicon and manganese.

There is a considerable difference in the in-service requirements imposed on spring steels, with automotive engine valve springs an example of the top end of the performance range. These have to operate with precision at a rate of several thousand compression cycles per minute over a normal engine lifespan of several thousand hours.

Most springs are made from hardened and tempered steel, though to ease the manufacture of larger springs these may be produced from annealed steel and hardened after fabrication.

Stainless Steel

Good corrosion resistance due to a high chromium content is the key characteristic. Opinions vary on the level of chromium (Cr) at which a steel becomes stainless, but it is at least 10.5%. Nickel (Ni) and molybdenum (Mo) are often present, and manganese, copper, titanium, silicon + other alloying elements may be added.

The principal grades are austenitic (typically 16-26%Cr, 6-22Ni); ferritic (10.5-28%Cr with no/low Ni); martensitic (higher carbon content than ferritic and typically 12-19%Cr with low/no Ni); and duplex, a dual-phase austenitic/ferritic steel (Cr>21%, Ni <8%).

Austenitics are non-magnetic, easily formed, but harden rapidly during processing (typically used in the process industries, heat exchangers, cutlery). Ferritics are less corrosion resistant, easily formed and magnetic (catering, architectural, materials handling). Martensitics are magnetic, have higher strength, are less easily worked (surgical instruments, shafts, fasteners). Duplex is strong with good impact resistance (desalination, heat exchangers).

Stainless steel was discovered in 1913 by Harry Brearly, a metallurgist from Sheffield.

Stamp charging

A method for improving the productivity of coke ovens by compacting, or stamping, the crushed coking coal prior to charging to the coke oven chamber.
This increases the bulk density of the charge by 30-35% and raises oven productivity by 10% or more. It also allows the use of a greater proportion of lower quality coal, and improves CSR (coke strength after reaction with CO2) values.

Standard tube

This tube or pipe is mostly used for conveying fluids such as air, water, gas and steam. It is distinct from linepipe, which is of much larger diameter and designed for transporting crude oil, gas and related hydrocarbon products in large volumes over long distances.

Some standard tube has mechanical applications, but the product that is designated as mechanical tube or pipe is generally produced to higher specifications in order to meet the requirements of a wide range of engineering applications in machinery or sub-assemblies.

In car and truck manufacture, for example, mechanical tube is used for drive shafts, steering and suspension parts, and in seat frames. But its applications are widespread, from appliances and agricultural and construction equipment to furniture.

Steckel mill

This is a piece of equipment usually associated with the production of flat rolled steel, and is essentially a reversing hot rolling mill where steel slab is reduced to strip by passing back and forth though either single or twin mill stands until the desired gauge is reached.

The key difference compared to the reversing mill is that a Steckel mill has coiling reels on the entry and exit sides of the mill stand to hold the steel between passes, instead of horizontal run-out tables. These coilers are usually enclosed and heated, allowing the temperature of the steel to be maintained during the rolling sequence.

The Steckel mill is a much less expensive and space consuming route to hot rolled coil than via a tandem mill, but the downside is far lower productivity and generally a lower quality product due to thermal issues.

Because of their restricted throughput, these mills are often installed at steelworks with annual outputs of up to around 1m tonnes/year, and where finished grades are normally produced in small batches –such as at stainless and speciality steel mills. Some carbon steel mini-mills also use them.

Steel

Steel is an alloy of iron and carbon which is produced from melting and refining pig iron and/or scrap iron, steel or DRI. It has a carbon content which is normally in the range 0.002% to 1.7%.

The proportion of carbon greatly influences the properties of the steel, but it is usually supplemented by other elements – most frequently manganese and silicon – to achieve certain physical properties such as hardness, ductility and strength.

Carbon steel is the most common form. Within this grouping mild steel generally has a carbon content of up to 0.25%, medium carbon steel contains carbon in the range 0.25-0.45%, and high carbon steel is above 0.45%.

Alloy steels, for example SBQ grades, and stainless and tool steels, have additional elements added, such as tungsten, chromium and nickel, to achieve a very specific in-service performance.

Stockholder

A steel merchant who maintains a stock of steel products in a warehouse for sale in small lots to end-users. The merchant will often undertake processing work, such as slitting coil, cutting-to-length and blanking to suit the steel to particular end-uses. Also known as a steel service centre when such additional processing is undertaken.

Strength
Strip

Thin flat steel normally produced in a continuous strip and wound into a coil weighing up to 40 tonnes for further processing.

Structural hollow sections
Structural steel

Structural steel is produced specifically for building construction with a specific shape or cross section, chemical composition and strength. These parameters and more, such as storage, are regulated to particular standards in most industrialised countries. (see also, wide flange beams)

Substrate

This is a prepared material on to which another finish or coating is to be applied.

For example, the substrate for continuously galvanized steel is steel coil which is free of corrosion, grease and other contaminants.

However, once galvanized, this coil often then becomes the substrate for a subsequent coating operation such as painting.

Surcharge

This is an addition to the normal mill price of steel to cover the cost of alloying elements used in producing certain grades. In some cases surcharges also reflect energy costs.

Surcharges were introduced when the price of alloying elements, such as nickel, became much more volatile, moving sharply away from their historic, and more stable, price range. Mills were faced with sharply escalating prices and introduced surcharges to protect their margins. Clearly over time surcharge values move down as well as up.

Apart from nickel, other elements typically factored into mill surcharge calculations include chrome, molybdenum, manganese, titanium, vanadium, silicon and iron (scrap).

Surcharges can play a very influential role in setting the transaction price (base price + surcharge) of stainless steel, and can significantly exceed the base price. They are also a factor in the pricing of other alloy steels like electrical sheet and engineering/SBQ* grades, as well as carbon steels in some markets (scrap surcharge).

Values are usually adjusted monthly based on recent past alloy/scrap price movements.

Swap

This typically refers to the exchange of an open futures contract for some other form of collateral. It could be swapped for another futures contract, for an option contract or for physical material.

Syndicated Loan

When there is a requirement for a very large loan, such as for financing a new steelworks, a group of banks, or other financial institutions qualified to conduct credit transactions, often work together as a syndicate to provide the necessary funds to the borrower.

Banks favour this approach to minimise their exposure to a default on the loan and to avoid large, unexpected losses. Up to 20 banks could be involved, though usually it is fewer.

There is always a lead bank, and although this arranges the syndicate it only guarantees the part of the loan that it commits to. There may be more than one lead bank. Participating banks are invited by the lead bank(s) to join the syndicate. The correspondent bank, which manages the loan, is usually the lead bank.

Taconite

Taconite is a relatively low grade source of iron ore, where the iron content, as magnetite* and some hematite is usually in the range 25-40%, and is present with other minerals such as quartz and carbonates. It is named after a type of rock formation found in the Taconic Mountains of New York state, USA.

Tailor Welded Blanks

These are shaped sheets made up by welding different grades and/or thicknesses of steel together to form a blank which is ready for final stamping by car makers – say for an inner door panel or engine compartment.

Tailor welded blanks (TWBs) were developed to reduce vehicle weight. Previously all car body parts had to be of a grade and thickness of steel capable of meeting the most demanding duties of that component. With TWBs it is possible to achieve a better utilisation of steel by putting material with appropriate properties and gauges only where it is needed. The rest can be cheaper steel.

As well as reducing weight, TWBs can reduce the number of parts and therefore final assembly costs. But clearly the cost savings in steel purchasing are offset by the higher costs of preparing a TWB versus a normal plain blanked sheet. Also their surface finish means they are not suitable for visible parts.

Tandem mill

See reversing mill.

Tap-to-tap time

This is a measure of productivity in electric arc furnace (EAF) steelmaking. It defines the time it takes to complete a melting cycle from the end of emptying (tapping) the molten steel produced in one melting operation to completion of tapping the steel from the next one.

Various refinements have helped to reduce tap-to-tap times so that a typical EAF cycle is now well under one hour. Principal amongst these was the introduction of electric refining furnaces. Steel from the EAF is transferred to an adjacent refining furnace for any melt composition adjustments prior to casting, so freeing the main furnace for charging and melting the next load.

Twin shell furnaces further reduce the tap-to-tap time. These have two adjacent melting vessels sharing a common power source. One of these is charged while the other is melting, and as soon as tapping of the first unit commences, power is transferred to the second furnace to commence melting.

Preheating scrap prior to charging using the EAF’s hot off-gases also helps cut melting times.

Technored

See Corex.

Temper mill
Temper rolling

A second cold rolling for coil in which the reduction in gauge is minimal. Can be used to achieve a bright finish.

Tempering

This is a heat treatment process applied to steels which have been hardened for a particular application (by heating and rapidly cooling), but as a result have become too brittle for the end-use for which they are intended.

To temper steel it is heated and held at an elevated temperature (but below its hardening or annealing* temperatures). This allows the metallurgical structure which was locked in place by the fast cooling used in the hardening process to modify itself slightly. The steel is then allowed to cool – usually slowly, though some steels can be cooled rapidly. The result is a strong, ductile and hard steel.

Steelmakers can achieve a wide range of key physical properties by careful control of tempering temperatures and process times.

Tension leveller
Terne plate

This is a thin lead/tin alloy coating applied to sheet steel for corrosion protection. The coating is typically alloyed in the ratio of about 80-90% lead to 10-20% tin with traces of antimony, the tin being present to ensure that the coating bonds effectively to the steel substrate.
Terne plate was first produced about 150 years ago, and the name is thought to derive from the French term for ‘dull’.
One of the main applications used to be for the production of automotive fuel tanks, with the coating acting as a lining for the internal surfaces, but a variety of factors, including legislation, weight and safety considerations, have seen the industry move away from this material.

Theoretical weight

The theoretical weight of a consignment of steel is a figure derived from a calculation based on steel density and product size.

It is quoted in kilograms/metre or kilograms/square metre depending on whether the calculation is for long products (using the steel’s cross sectional dimension), or for flat products (when thickness is the key dimensional input). A typical standard reference would be 7.85kg/mm thickness of 1square metre of carbon steel.

Formulae exist for calculating the theoretical weight of simple profiles like round bar and plate, or for more complicated shapes like hexagonal bars, channels and beams (taking into account any radii). Special handheld calculators can be bought for this task.

Because of dimensional deviations during rolling, the calculated theoretical weight of a finished consignment of steel is likely to be different to the actual value, and for this reason it is generally only used when a piece count is important for stockists, or for reference purposes during estimating.

Thin slab casting

In steelworks producing flat rolled products, molten steel is continuously cast into slabs in excess of 200mm thick. These are either allowed to cool before reheating for hot rolling, or kept hot in a nearby furnace before being sent on to the hot mill.

With thin slab casting (TSC) the molten steel is cast as a much thinner slab – usually around 50-60mm thick. This allows the mill to use a simpler hot rolling line (no roughing/breakdown mill) so reducing capital and operating costs. Connecting the exit of the caster to the entry of the hot mill with a tunnel furnace is common practice to minimise energy losses and shorten overall production times.

Because TSC was pioneered by scrap-based mini-mills (like Nucor) who were targeting the less sophisticated part of the flat rolled steel market, they could also cut costs by having fewer mill stands in the hot mill – typically four rather than six or seven.

Thin strip casting

Unlike slab and thin slab casting, this route produces 1-2mm thick steel strip direct from the caster, thus eliminating much of the rolling equipment associated with 200mm-plus thick conventional slabs, and 50-60mm thin slabs.

The first such commercial plant, at Nucor’s Crawfordsville steelworks in the USA (which also pioneered thin slab casting), employs a single-stand hot rolling mill immediately following the caster to further reduce the thickness of the 1,350mm wide strip to below 1mm.

At the heart of the strip casting process are two horizontal counter-rotating rolls separated by a narrow gap. Steel poured into the cavity formed by the top part of these adjacent rolls solidifies by the time it emerges from the gap between them.

Apart from the lower capital cost associated with thin strip casting, the minimal rolling requirements and elimination of any slab reheating or temperature maintenance between casting and rolling stages, reduces operating costs.

Nucor’s plant was operating commercially by 2005, but take-up of the technology elsewhere has been slow.

Tin Free Steel

Although classed along with tinplate as a tinmill product, tin-free steel is a chromium-coated, corrosion-resistant steel which, like tinplate, is used for food and other packaging applications. It is correctly known as electrolytic chromium coated steel (ECCS).

The coating is applied to a cold-rolled, low-carbon steel coil substrate in a continuous electrolytic process using chromic acid. The result is a very thin layer of chromium and chromium oxide.

Apart from its packaging uses, it does find other applications, such as in some electrical equipment.

Compared to tinplate, ECCS is easier to recycle because tin is a contaminant in scrap.

Tinplate

Tinplate is cold reduced steel sheet coated with a thin layer of tin. It has good corrosion resistance and food compatibility – although many products require a thin coating of lacquer to maximise the shelf life of the contents.

Around 90% of tinplate is used in packaging, with food and drinks cans the biggest market, but it is also widely used for other consumer and general packaging, such as aerosols, paints and oils.

Tin is applied in a continuous process where decoiled steel (tinplate feedstock is called blackplate) passes through an electrolytic plating bath containing tin in solution.

Tinplate can be produced with different coating thicknesses on either side of the sheet. The coating on each side is typically in the range 2.8-5.6 grams/sq metre, but can be 1-14 g/m2. (11.2 g/m2 on each side equates to one pound “per basis box”, a unit of measure still used in the USA.)

Overall tinplate thickness is usually in the range 0.13-0.49mm.

Toll Processing

Toll Processing describes an arrangement where the producer or owner of a metallurgical raw material, or of a partly or fully rolled metal product, sends this for further treatment by a third party prior to further in-house processing or sale. He receives back the original material in a different form, and while the third party charges for the work undertaken, it has no ownership rights.

In the steel industry, tolling work usually relates to additional rolling operations or the application of final coatings or special finishes. The term hire rolling is also widely used.

In other parts of the metals industry, toll processing is used to transform raw materials into primary metal, and at times it has been particularly prevalent in aluminium (alumina smelted into slab or ingot).

The decision whether to process steel in-house or externally can be down to a number of factors, including historical precedent, economics of production, or commercial confidentiality.

Ton

The ton is a unit of weight, but takes various forms. A metric ton (usually written tonne) is 1,000 kilograms (kg) and is the most widely used.

A long ton is 2,240 pounds (lb). Historically it was used across the British empire, but now is only likely to be encountered in the USA for bulk commodities like scrap and iron ore. Also know as a gross ton. (Equates to 1.015 tonnes)

A short ton is 2,000lb and is predominant in the USA. Also known as a net ton, and in South Africa as a harbour ton. (Equates to 0.906 tonnes)

There are other tons. Deadweight ton (dwt) is a measure of a ship’s carrying capacity (cargo, fuel, crew etc). Traditionally measured in long tons, this is increasingly being quoted in tonnes.

Tool steels

Carbon and alloy steels for making tools used in a wide range of applications – cutting, punching, pressing, forging, digging, moulding and extrusion.

Key requirements are hardness and resistance to abrasion so that tools remain effective over long periods. Resistance to deformation is also important, as is toughness and good compressive and impact resistance. Good machinability can be a requirement.

Carbon content is in the range 0.4-2.1%, and the steel may contain several of the following alloying elements: manganese, chromium, tungsten, silicon, molybdenum, vanadium, nickel and cobalt. Some tool steels are stainless steels.

Tool steels are heat treated, and the higher carbon grades tend to be for cutting and stamping applications. Those categorised as “cold working” are for applications where surface temperatures remain below 200oC; “hot working” denotes applications above 200 °C.

Torpedo ladle

Torpedo ladles – or torpedo cars – are large, well insulated vessels used to transport liquid iron from blast furnace to steel converter.
 
 They have a distinctive appearance, being long, circular in cross-section, but with a larger circumference in the middle than at either end. Clearly good, robust insulation is essential to prevent significant heat loss or a blow-out and spillage of the metal.
 
 Torpedo ladles can contain several hundred tonnes of iron at temperatures approaching 1,500oC, and are moved by locomotive along dedicated rail tracks. They may travel just a few hundred metres or up to several kilometres.
 
 A modern blast furnace can produce around 10,000 tonnes of iron daily, so several torpedo ladles would normally be in use.

Toughness, hardness, ductility, strength

Toughness is a measure of a material’s ability to resist fracture by absorbing the stress and strain imposed by sudden loading/impact. It tends to improve with increasing temperature.

Tough material may undergo some deformation in absorbing sudden impacts, and a very tough material will have high strength (ability to resist deformation) and high ductility (ability to change shape without failure). Toughness is the opposite of brittleness.

Hardness defines a material’s ability to resist permanent deformation or changes to its shape when under load, or to resist cutting, scratching or other forms of abrasion. So in general, the harder a material the greater its wear resistance.

Traded option
Tube

See seamless and welded tube/pipe.

Tube shell

This is the feedstock for seamless tube rolling mills. It takes the form of a billet which has been pierced to form a basic tube form ready for further rolling to the desired diameter and wall thickness.

Tundish

The tundish is a refractory lined vessel whose role is to provide a reservoir of molten metal for the continuous casting of steel slab, billets or blooms.

Newly produced liquid steel is transferred from the basic oxygen furnace (BOF), electric arc furnace (EAF) or ladle furnace (LF) into this holding vessel which is positioned at the top of the caster.

A short refractory pipe directs the metal from a hole in the base of the tundish to the top of the caster mould(s).

Some casters are equipped with a ladle turret. This can hold two ladles from the meltshop and its use facilitates long casting sequences. The second ladle is moved into position over the tundish once the first ladle is emptied (and returned to the meltshop for refilling) so keeping the tundish well charged with liquid steel.

Tunnel furnace

These are long, horizontal, refractory-lined, heated rectangular enclosures which are used to maintain steel semis leaving the caster at rolling temperature as they are transferred to the rolling mill.

Their function is to save energy and raise productivity by avoiding the usual cooling and subsequent reheating of semis prior to hot rolling. The furnace, which can be more than 100 metres long, also acts as a buffer between caster and mill to assist rolling mill scheduling.

As semis move slowly through the tunnel, conveyed by a series of rolls, their temperature is maintained by burners mounted at intervals along the sidewalls.

Tunnel furnaces were first developed around 20 years ago with the advent of thin slab casting.

Turned bar
Vacuum degassing

Vacuum degassing (VD) is used following steel making to reduce the carbon, nitrogen, hydrogen and sulphur content of molten steel. Phosphorus can also be reduced. The process takes place under vacuum in a ladle furnace, and is frequently employed by both volume and special steels producers.

When dealing with high-chromium steels, VD allows very low carbon content to be achieved without heavy chromium losses from the melt.

Vacuum degassing has become widespread as demand for higher quality steels has grown in sectors like automotive, construction, offshore, pipe making and rails. In alloy steel products like bearings VD steels improve fatigue life, while in flat products, very low carbon VD steels are well suited to demanding processing and fabrication.

Vanadium

About 80% of world vanadium production goes into steelmaking, but it is also an important constituent of certain high performance non-ferrous aerospace alloys. It is usually added to steel as a ferro-alloy (FeVa).

In steel, vanadium increases tensile strength, toughness and fatigue resistance, as well as improving the hardenability of some grades and conferring rust resistance. An early application was armour plate.

Today, vanadium’s main applications are in high-strength low-alloy sheet for the automotive sector, in engineering steels – such as for axles, crankshafts and gears – and in spring and high-speed tool steels. In stainless steels it is typically used for producing grades needed for applications like surgical instruments.

Vertical edgers

These are used in conjunction with roughing mills to ensure correct slab width prior to further rolling. The edger’s rolls keep the sides of the steel slab square as well as controlling width.

VOD

Vacuum oxygen decarburisation is a method for reducing the carbon content of molten steel. Oxygen is blown on to the surface of the metal, which is held in sealed vessel at reduced pressure. Very low carbon levels are possible. This method is often used in stainless steel production.

Volatile matter

In coking coal this term refers to any constituents of the coal, apart from moisture, which are released (vaporised) at higher temperatures. These are usually mostly hydrocarbons, but also sulphur.
Along with other properties such as ash and moisture content, volatile matter content is one of the key parameters used in defining the quality of a coal.

Walking beam furnace
Warrant

In the context of metals trading on the London Metal Exchange, a warrant is a document signifying title to a particular consignment or lot of metal, stored in a defined location within a specific LME approved warehouse.

Every warrant states the brand of the metal, the number of pieces, the overall weight of the consignment or batch, and the storage rental.

Prior to receiving the warrant, the buyer will not necessarily know the specific LME approved brand or grade of the metal he has bought, nor its precise location.

The existence of approved warehouses as a point of delivery or source of metal against exchange contracts in times of metal surplus or shortage, is fundamental to the LME’s status as a physically deliverable market.

It is the responsibility of the warehouse to check that the identity of the metal is visible, that it is kept in good condition and is properly secured.

Welded tube/pipe

This is made from hot rolled or cold reduced strip, sheet or plate. Small and medium diameters are produced in continuous, multiple-roll mills that progressively bend incoming, unheated strip into a circular cross-section prior to welding along the longitudinal seam. Tube may subsequently be cold-drawn through dies to achieve precise dimensions and finish.

This is cheaper than the seamless process but welded tube generally has a lower mechanical and pressure performance.

Large diameters are made from discrete plate. First this is bent into a “U” shape, then an “O” shape, which is welded prior to mechanical or hydraulic expansion – the “E” of the UOE process – to achieve final dimensions. This pipe can be 400-1,600mm diameter.

Spiral welded tube/pipe uses HR strip that is twisted as it goes through a mill to form a hollow spiral which is then welded. It is cheap to make but has traditionally had a lower integrity than conventional welded pipe – though it is improving. Diameters of up to 2,500mm are possible.

Welding

This method of joining metals is essential for certain types of pipemaking and is widely used in structural steel fabrication, shipbuilding etc.

The workpieces are melted at the point where they are to be joined using a very localised, high temperature energy source, and a filler material is added to create a small additional amount of molten metal. When this cools the workpieces fuse together to form a strong joint. Pressure is sometimes applied to the workpieces during welding.

The commonly used energy sources are an electric arc and a gas flame.

Submerged arc welding (SAW) is widely used in the large scale production of steel tube and pipe from strip, sheet or plate. In this electric arc process, the molten weld area is protected from the atmosphere by a layer of conductive flux in order to prevent any contamination.

Wide Flange Beams

These heavy duty structural sections are often referred to as H-beams and I-beams (because of their cross-sectional appearance). They are mainly used in the frames of industrial and hi-rise structures, are internationally traded and are a stockholder item in standard lengths. Dimensions are in metric, except in the USA where they are sold as “W” shapes in inches.

H-beams are mainly hot rolled from blooms. They are classified by depth (web plus end-flange thickness – hence the “W” notation in the US) and weight per unit length. These parameters are typically up to 1,000mm-plus and 600 kg/metre respectively.

They are sometimes confused with I-beams, which have similar uses but narrower flanges and smaller web depths and steel thicknesses.

Wire Drawing

This is the process by which steel wire is produced from a larger diameter feedstock, usually wire rod.


Wire is the smallest diameter steel product, and to achieve the gauges needed for manufacturing items like fencing, nails, tyrecord and ultra-fine filtration gauzes, the cold rod is pulled through a series of drawing dies, each of successively smaller bore diameter.


A continuous multi-die wire-drawing machine can have up to 15 blocks, each containing a die. These have a metal casing but the forming hole is made in a ‘nib’ of tungsten carbide, or natural or synthetic diamond. Though mostly round, wire can be flat or have other profiles.


A wide range of steels may be drawn, from the mild steel used for paper clips and champagne cork wire, to spring grades and the high strength steels needed for suspension bridge cables and piano wire.

Wire Rod

Hot rolled from low, medium and high carbon or alloy steel billet, wire rod is delivered as coil, most commonly at 5.5mm dia, but in sizes up to 60mm dia. Close control of final cooling is a critical part of production.

Low carbon rod is used for undemanding applications like fencing wire and concrete reinforcing mesh, while medium and high carbon rod goes into higher performance uses like steelcord for car tyre reinforcement.

Some rod (cold heading carbon and alloy grades) is used to make fasteners (bolts, screws, nails, rivets), and alloy rod is commonly machined into products like engineering bearings. Some rod provides filler metal in welding operations.

Work rolls
Wrought iron

This is a type of iron, which unlike hard, brittle pig iron – such as is tapped from a blast furnace – is tough and malleable, allowing it to be forged and welded. It has a high tensile strength and is more corrosion resistant than steel.

Wrought iron has a very low carbon content – lower than many steels – but importantly it has traces of manganese/sulphur/phosphorus/silicon-containing slag which give it a fibrous structure and which contributes to its desirable properties.

Production is by melting and then stirring new pig iron or scrap cast iron to lower the carbon content, a process known as “puddling”. This is followed by forging to optimise slag content.

Wrought iron was widely used for structural, engineering and decorative applications, and consumption declined after the mid-nineteenth century once steel became more widely available. Small amounts are produced today for artistic applications and restoration work.

Arguably the most famous example of wrought iron in action is the Eiffel Tower, Paris.

Wrought metals

Metals which after melting, casting and solidifying have been further worked in a hot or cold condition to alter their shape and/or dimensions by rolling, forging, extruding and drawing.

Z-mill
Zeroing

This is the practice when making steel dumping calculations of counting negative anti-dumping margins as zero, and not allowing them to fully offset positive margins in order to keep any margins that are imposed artificially high.

In steel it is a practice which in recent years is particularly associated with the USA, and the continued use of zeroing is routinely challenged by the European Commission, most recently at WTO hearings.

The key argument against zeroing is that without it the dumping margin could be “de minimis” (too small to be worth enforcing), or even negative.

Trade policy observers have long considered this to be a fundamentally distortive practice, as it almost always ensures the finding of dumping margins.

 

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