AISI | Steel Glossary

Everything You Always Wanted to Know About Steel…But Were Afraid to Ask - December 2004

Michelle Applebaum Research provides this collection of terms and concepts used in our research, company and industry reports, and other steel publications as an invaluable tool for those in the steel industry.

Reproduction of all or part of this glossary is specifically prohibited without the written consent of the author.

Pronunciation: stēl
Function:noun
Etymology: Middle English stele, from Old English style, stEle; akin to Old High German stahal steel and perhaps to Sanskrit stakati he resists

1 commercial iron that contains carbon in any amount up to about 1.7 percent as an essential alloying constituent, is malleable when under suitable conditions, and is distinguished from cast iron by its malleability and lower carbon content

2 an instrument or implement of or characteristically of steel: as a : a thrusting or cutting weapon b : an instrument (as a fluted round rod with a handle) for sharpening knives c : a piece of steel for striking sparks from flint

3 a quality (as hardness of mind or spirit) that suggests steel <nerves of steel>

4 a : the steel manufacturing industry b plural : shares of stock in steel companies

Fine particles of limestone (flux) and iron ore are difficult to handle and transport because of dusting and decomposition. The powdery material is therefore usually processed into larger pieces. The raw material’s properties determine the technique that is used by mills.

Baked particles that stick together in roughly one-inch chunks. Normally used for iron ore dust collected from the blast furnaces.

Iron ore or limestone particles are rolled into little balls in a balling drum and hardened by heat.

Small lumps are formed by pressing material together. Hot Briquetted Iron (HBI) is a concentrated iron ore substitute for scrap for use in electric furnaces.

A change in the properties of certain metal and alloys (such as steel) that occurs at ambient or moderately elevated temperatures after a hot working heat treatment or cold working operation. Typical properties impacted are: hardness, yield strength, tensile strength, ductility, impact value, formability, magnetic properties, etc.

An association of North American companies that mine iron ore and produce steel products. There are 31 member companies and 118 associate members, which include both suppliers and customers that distribute, process, or consume steel. The AISI represents the interests of Canada, Mexico, and the United States.

Any metallic element added during the melting of steel or aluminum for the purpose of increasing corrosion resistance, hardness, or strength. The metals used most commonly as alloying elements in stainless steel include chromium, nickel, and molybdenum.

An iron-based mixture is considered to be an alloy steel when manganese is greater than 1.65%, silicon over 0.5%, copper above 0.6%, or other minimum quantities of alloying elements such as chromium, nickel, molybdenum, or tungsten are present. An enormous variety of distinct properties can be created for the steel by substituting these elements in the recipe.

Steel deoxidized with aluminum in order to reduce the oxygen content to a minimum so that no reaction occurs between carbon and oxygen during solidification.

A heat or thermal treatment process by which a previously cold-rolled steel coil is made more suitable for forming and bending. The steel sheet is heated to a designated temperature for a sufficient amount of time and then cooled.

The bonds between the grains of the metal are stretched when a coil is cold-rolled, leaving the steel brittle and breakable. Annealing “recrystallizes” the grain structure of steel by allowing for new bonds to be formed at the higher temperature.

1. Batch (Box) Three to four coils are stacked on top of each other, and a cover is placed on top for up to 3 days, then heated in a non-oxygen atmosphere (to prevent rust) and slowly cooled.

2. Continuous. Normally part of a coating line, the steel is uncoiled and run through a series of vertical loops within a heater. The temperature and cooling rates are controlled to obtain the desired mechanical properties for the steel.

Derived demand for steel using AISI reported steel mill shipments plus Census Bureau reported imports, less Census Bureau reported exports. Domestic market share percentages are based on this figure, which does not take into account any changes in inventory.

A process for further refinement of stainless steel through reduction of carbon content.

The amount of carbon in stainless steel must be lower than that in carbon steel or lower alloy steel (i.e., steel with alloying element content below 5%). While electric arc furnaces (EAF) are the conventional means of melting and refining stainless steel, AOD is an economical supplement, as operating time is shorter and temperatures are lower than in EAF steelmaking. In addition, using AOD for refining stainless steel increases the availability of the EAF for melting purposes.

Molten, unrefined steel is transferred from the EAF into a separate vessel. A mixture of argon and oxygen is blown from the bottom of the vessel through the melted steel. Cleaning agents are added to the vessel along with these gases to eliminate impurities, while the oxygen combines with carbon in the unrefined steel to reduce the carbon level. The presence of argon enhances the affinity of carbon for oxygen and thus facilitates the removal of carbon.

A natural reduction in work force as a result of resignations, retirements, or death.

Most unionized companies cannot unilaterally reduce their employment levels to cut costs, so management must rely on attrition to provide openings that it, in turn, does not fill. Because the median ages of work forces at the integrated mills may be more than 50, an increasing number of retirements may provide these companies with added flexibility to improve their competitiveness.

The largest category of stainless steel, accounting for about 70% of all production. The austenitic class offers the most resistance to corrosion in the stainless group, owing to its substantial nickel content and higher levels of chromium. Austenitic stainless steels are hardened and strengthened through cold working (changing the structure and shape of steel by applying stress at low temperature) instead of by heat treatment. Ductility (ability to change shape without fracture) is exceptional for the austenitic stainless steels. Excellent weldability and superior performance in very low-temperature services are additional features of this class.

Applications include cooking utensils, food processing equipment, exterior architecture, equipment for the chemical industry, truck trailers, and kitchen sinks.

The two most common grades are type 304 (the most widely specified stainless steel, providing corrosion resistance in numerous standard services) and type 316 (similar to 304, with molybdenum added, to increase opposition to various forms of deterioration).

A facility that presses a steel blank into the desired form of a car door or hood, for example, with a powerful die (pattern). The steel used must be ductile (malleable) enough to bend into shape without breaking.

Using hydraulic roll force systems, steelmakers have the ability to control precisely their steel sheet’s gauge (thickness) while it is traveling at more than 50 miles per hour through the cold mill. Using feedback or feed-forward systems, a computer’s gap sensor adjusts the distance between the reduction rolls of the mill 50–60 times per second. These adjustments prevent the processing of any off-gauge steel sheet.

An air pollutant control device used to trap particles by filtering gas streams through large cloth or fiberglass bags.

A cold-rolled, low-carbon sheet steel used for automotive body panel applications. Because of special processing, the steel has good stamping and strength characteristics, and, after paint is baked on, improved dent resistance.

A pear-shaped furnace, lined with refractory bricks, that refines molten iron from the blast furnace and scrap into steel. Up to 30% of the charge into the BOF can be scrap, with hot metal accounting for the rest.

BOFs, which can refine a heat (batch) of steel in less than 45 minutes, replaced open-hearth furnaces in the 1950s; the latter required five to six hours to process the metal. The BOF’s rapid operation, lower cost, and ease of control give it a distinct advantage over previous methods.

Scrap is dumped into the furnace vessel, followed by the hot metal from the blast furnace. A lance is lowered from above, through which blows a high-pressure stream of oxygen to cause chemical reactions that separate impurities as fumes or slag. Once refined, the liquid steel and slag are poured into separate containers.

Long steel products that are rolled from billets. Merchant bar and reinforcing bar (rebar) are two common categories of bars, where merchants include rounds, flats, angles, squares, and channels that are used by fabricators to manufacture a wide variety of products such as furniture, stair railings, and farm equipment. Rebar is used to strengthen concrete in highways, bridges, and buildings.

A semi-finished steel form that is used for “long” products: bars, channels or other structural shapes. A billet is different from a slab because of its outer dimensions; billets are normally two to seven inches square, while slabs are 30 inches to 80 inches wide and two inches to ten inches thick. Both shapes are generally continually cast, but they may differ greatly in their chemistry.

Cold-reduced sheet steel, 12 inches to 32 inches wide, that serves as the substrate (raw material) to be coated in the tin mill.

A towering cylinder lined with heat-resistant (refractory) bricks, used by integrated steel mills to smelt iron from iron ore. Its name comes from the “blast” of hot air and gases forced up through the iron ore, coke, and limestone that load the furnace.

An early step in preparing flat-rolled steel for use by an end user. A blank is a section of sheet that has the same outer dimensions as a specified part (such as a car door or hood), but that has not yet been stamped. Steel processors may offer blanking for their customers to reduce their labor and transportation costs; excess steel can be trimmed prior to shipment.

A semi-finished steel form, with a rectangular cross-section that is more than 8”. This large cast steel shape is broken down in the mill to produce the familiar I-beams, H-beams, and sheet piling. Blooms are also part of the high-quality bar manufacturing process: Reduction of a bloom to a much smaller cross-section can improve the quality of the metal.

An accident caused by the failure of the walls of the hearth of the blast furnace, resulting in liquid iron or slag (or both) flowing uncontrolled out of the blast furnace.

A “brownfield” contrasts to a “greenfield” (or a facility new from the ground up). A brownfield expansion means adding on to an existing facility.

The very subtle ridge on the edge of strip steel left by cutting operations such as slitting, trimming, shearing, or blanking. For example, as a steel processor trims the sides of the sheet steel parallel or cuts a sheet of steel into strips, its edges will bend with the direction of the cut (see Edge Rolling).

Scrap consisting of sheet clips and stampings from metal production. This term arose from the practice of collecting the material in bushel baskets through World War II.

The standard pipe used in plumbing. Heated skelp is passed continuously through welding rolls, which form the tube and squeeze the hot edges together to make a solid weld.

1 Camber is the deviation of a side edge from a straight edge. Measurement is taken by placing a straight edge on the concave side of a sheet and measuring the distance between the sheet edge and the straight edge in the center of the arc. Camber is caused by one side being elongated more than the other.

Camber is the deviation from edge straightness. Maximum allowable tolerance of this deviation of a side edge from a straight line are defined in ASTM Standards.

Normal ability to produce metals in a given time period. This rating should include maintenance requirements, but because such service is scheduled to match the needs of the machinery (not those of the calendar), a mill might run at more than 100% of capacity one month and then fall well below rated capacity as maintenance is performed.

The theoretical volume of a mill or smelter, given its constraints of raw material supply and normal working speed.

Volume at full utilization, allowing for the maintenance of equipment and reflecting current material constraints. (Bottlenecks of supply and distribution can change over time — capacity will expand or reduce.)

Steel that has properties made up mostly of the element carbon and which relies on the carbon content for structure. Most of the steel produced in the world is carbon steel.

Casing is the structural retainer for the walls of oil and gas wells, and accounts for 75% (by weight) of OCTG shipments. Casing is used to prevent contamination of both the surrounding water table and the well itself. Casing lasts the life of a well and is not usually removed when a well is closed.

The process of pouring molten metal into a mould so that the cooled, solid metal retains the shape of the mould.

Process to directly cast molten steel into a final shape and thickness without additional hot or cold rolling. This reduces capital investment, energy, and environmental cost.

The act of loading material into a vessel. For example, iron ore, coke, and limestone are charged into a Blast Furnace; a Basic Oxygen Furnace is charged with scrap and hot metal.

The chemical composition of steel indicating the amount of carbon, manganese, sulfur, phosphorous and a host of other elements.

An alloying element that is the essential stainless steel raw material for conferring corrosion resistance. A film that naturally forms on the surface of stainless steel self-repairs in the presence of oxygen if the steel is damaged mechanically or chemically, and thus prevents corrosion from occurring.

Method of applying a stainless steel coating to carbon steel or lower alloy steel (i.e., steel with alloying element content below 5%).

To increase corrosion resistance at lower initial cost than exclusive use of stainless steel.

By 1) welding stainless steel onto carbon steel; 2) pouring melted stainless steel around a solid carbon steel slab in a mold; or 3) placing a slab of carbon steel between two plates of stainless steel and bonding them by rolling at high temperature on a plate mill.

The process of covering steel with another material (tin, chrome, and zinc), primarily for corrosion resistance.

Metal sheet that has been wound. The metal, once rolled flat, is more than one-quarter mile long; coils are the most efficient way to store and transport sheet steel.

The basic fuel consumed in blast furnaces in the smelting of iron. Coke is a processed form of coal. About 1,000 pounds of coke are needed to process a ton of pig iron, an amount which represents more than 50% of an integrated steel mill’s total energy use.

Metallurgical coal burns sporadically and reduces into a sticky mass. Processed coke, however, burns steadily inside and out, and is not crushed by the weight of the iron ore in the blast furnace.

Inside the narrow confines of the coke oven, coal is heated without oxygen for 18 hours to drive off gases and impurities.

A set of ovens that process coal into coke. Coke ovens are constructed in batteries of ten to 100 ovens that are 20 feet tall, 40 feet long, and less than two feet wide. Coke batteries, because of the exhaust fumes emitted when coke is pushed from the ovens, often are the dirtiest area of a steel mill complex.

Finishing mills roll cold coils of pickled hot-rolled sheet to make the steel thinner, smoother, and stronger by applying pressure, rather than heat.

Stands of rolls in a cold-reduction mill are set very close together and press a sheet of steel from one-quarter inch thick into less than an eighth of an inch, while more than doubling its length.

Sheet steel that has been pickled and run through a cold-reduction mill. Strip has a final product width of approximately 12 inches, while sheet may be more than 80 inches wide. Cold-rolled sheet is considerably thinner and stronger than hot-rolled sheet, so it will sell for a premium (see Sheet Steel).

Changes in the structure and shape of steel achieved through rolling, hammering, or stretching the steel at a low temperature (often room temperature).

The application of forces to the steel causes changes in the composition that enhance certain properties. In order for these improvements to be sustained, the temperature must be below a certain range, because the structural changes are eliminated by higher temperatures.

Measures the physical use of a metal by end users. Metal consumption estimates, unlike steel demand figures, account for changes in inventories.

A method of pouring steel directly from the furnace into a billet, bloom, or slab directly from its molten form.

Continuous casting avoids the need for large, expensive mills for rolling ingots into slabs. Continuous cast slabs also solidify in a few minutes versus several hours for an ingot. Because of this, the chemical composition and mechanical properties are more uniform.

Steel from the BOF or electric furnace is poured into a tundish (a shallow vessel that looks like a bathtub) atop the continuous caster. As steel carefully flows from the tundish down into the water-cooled copper mold of the caster, it solidifies into a ribbon of red-hot steel. At the bottom of the caster, torches cut the continuously flowing steel to form slabs or blooms.

Metal products committed to customers through price agreements extending three to 12 months. About one-half of all flat-rolled steel is sold on this basis, primarily because the auto companies sign agreements to cover at least one year’s model. Price increases that the steel mills might announce during the year do not generally affect the revenues from the contract side of the business.

Resources spent to process material in a single stage, from one type to another. The costs of converting iron ore to hot metal or bauxite to aluminum can be isolated for analysis.

Processes steel into a more finished state, such as pipe, tubing, and cold-rolled strip, before selling it to end users. Such steel generally is not sold on contract, making the converter segment of the mills’ revenues more price sensitive than their supply contracts to the auto manufacturers.

COREX® is a coal-based smelting process that yields hot metal or pig iron. The output can be used by integrated mills or EAF mills.

The process gasifies non-coking coal in a smelting reactor, which also produces liquid iron. The gasified coal is fed into a shaft furnace, where it removes oxygen from iron ore lumps, pellets, or sinter; the reduced iron is then fed to the smelting reactor.

The gradual degradation or alteration of metal caused by atmosphere, moisture, or other agents.

Heavy gauge, galvanized steel that is spiral-formed or riveted into corrugated pipe, which is used for highway drainage applications.

Process to uncoil sections of flat-rolled steel and cut them into a desired length. Product that is cut to length is normally shipped flat-stacked.

Parts/applications that require deep drawing in their fabrication. Examples are motor shells, fenders, quarter panels, and door panels.

A type of pension plan whereby the employer promises to make pension payments to retired employees in specified amounts, regardless of the performance of the fund. Because the employees’ total years of service and their length of retirement are uncertain, the employer’s future liabilities must be estimated and can fluctuate over time.

A pension plan in which the employer promises to make specified contributions to the pension fund, but the amount of pension benefits ultimately paid to retired employees depends on how well the pension fund’s assets are managed. There are no balance sheet items for Defined Contribution Plans because all liabilities are satisfied in full each year.

The process of removing scale from the surface of steel. Scale forms most readily when the steel is hot by union oxygen with iron. Common methods are: (1) crack the scale by use of roughened rolls and remove by a forceful water spray, (2) throw salt or wet sand or wet burlap on the steel just previous to its passage through the rolls.

Operation that injects a chemical mixture into a ladle full of hot metal to remove sulfur prior to its charging into the Basic Oxygen Furnace.

Sulfur enters the steel from the coke in the blast furnace smelting operation, and there is little the steelmaker can do to reduce its presence. Because excess sulfur in the steel impedes its welding and forming characteristics, the mill must add this step to the steelmaking process.

Processed iron ore that is iron-rich enough to be used as a scrap substitute in electric furnace steelmaking.

As mini-mills expand their product abilities to sheet steel, they require much higher grades of scrap to approach integrated mill quality. Enabling the mini-mills to use iron ore without the blast furnace, DRI can serve as a low residual raw material and alleviate the mini-mills’ dependence on cleaner, higher priced scrap.

The impurities in the crushed iron ore are driven off through the use of massive amounts of natural gas. While the result is 97% pure iron (compared with blast furnace hot metal, which, because it is saturated with carbon, is only 93% iron), DRI is only economically feasible in regions where natural gas is attractively priced.

A procedure for producing specialty tubing using a drawbench to pull tubing through a die and over a mandrel, giving excellent control over the inside diameter and wall thickness. Advantages of this technique are its inside and outside surface quality and gauge tolerance. Major markets include automotive applications and hydraulic cylinders.

Pipe used in the drilling of an oil or gas well. Drill pipe is the conduit between the wellhead motor and the drill bit. Drilling mud is pumped down the center of the pipe during drilling, to lubricate the drill bit and transmit the drilled core to the surface. Because of the high stress, torque and temperature associated with well drilling, drill pipe is a seamless product.

Ability of steel to undergo permanent changes in shape without fracture at room temperature.

Dumping occurs when imported merchandise is sold in, or for export to the domestic market at less than the normal value of the merchandise — that is, at a price that is less than the price at which identical or similar merchandise is sold in the comparison market, the home market (the market of the exporting country), or third-country market (in this case, “market” is used as proxy for “home market” in cases where home market cannot be used). The normal value of the merchandise cannot be below the cost of production.

The amount by which the normal value exceeds the export price or constructed export price of the subject merchandise.

A category of stainless steel with high amounts of chromium and moderate nickel content. The duplex class is so named because it is a mixture of austenitic (chromium-nickel stainless class) and ferritic (plain chromium stainless category) structures. This combination was originated to offer more strength than either of those stainless steels. Duplex stainless steels provide high resistance to stress corrosion cracking (formation of cracks caused by a combination of corrosion and stress) and are suitable for heat exchangers, desalination plants, and marine applications.

Rolling a strip of steel to smooth the edges. By removing the burr off the coil, it is safer for customers to manipulate.

Steel-making furnace where scrap is generally 100% of the charge. Heat is supplied from electricity that arcs from the graphite electrodes to the metal bath. Furnaces may be either an alternating current (AC) or direct current (DC). DC units consume less energy and fewer electrodes, but they are more expensive.

Pipe made from strips of hot-rolled steel which are passed through forming rolls and welded. While seamless pipe is traditionally stronger and more expensive than comparable ERW pipe, ERW technology is improving and the technique now accounts for approximately 48% of OCTG shipments by tonnage.

Cold Rolled or Black Plate to which a coating of zinc is applied by electro-deposition; used for applications in which corrosion resistance and paintability is a primary concern.

Cold rolled sheets coated with tin by electro-deposition through an acid or alkaline process.

The process used on stainless steel tubing and fittings to simultaneously smooth, brighten, clean, and passivate the interior surfaces of these components. Electropolishing is an electrochemical removal process that selectively removes a thin layer of metal, including surface flaws and imbedded impurities. Electropolishing is a required surface treatment process for all ultra high-purity components used in the gas distribution systems of semiconductor manufacturers worldwide and many sterile water distribution systems of pharmaceutical and biotechnology companies.

The process of shaping material by forcing it to flow through a shaped opening in a die.

DISCLAIMER: The information, opinions, estimates and projections contained in the accompanying message were prepared by Michelle Applebaum Research Inc ("MARI") and constitute the current judgment of MARI as of the date of this report. Additional information may be available from MARI upon request. The information contained herein is believed to be reliable and has been obtained from sources believed to be reliable, but MARI makes no representation or warranty, either express or implied, as to the accuracy, completeness or reliability of such information. MARI does not undertake, and has no duty, to advise you as to any information that comes to its attention after the date of the accompanying message or any changes in its opinion, estimates or projections. The information in the accompanying message is not intended to meet the objectives or needs of specific investors, but is intended as impersonal advisory services. MARI, our affiliates, and any officer, director or stockholder, or any member of their families may have a position in and may from time to time purchase or sell any of the securities mentioned or any related securities. MARI is not a registered broker-dealer. This is not a solicitation of any offer to buy or sell securities.

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