Stainless Steel - Definition of Industry Terms (Glossary)
Martensitic stainless steels are hardened by heating above their critical temperature, holding them at heat to ensure uniform temperature, and cooling them rapidly by quenching in air or oil.
AISI (American Iron and Steel Institute)
A North American trade association with 50 member companies and over 100 associate members. These companies represent the United States, Canada, and Mexico in all aspects of the steel industry.
The adding of any metallic element in stainless steel production in order to increase hardness, strength, or corrosion resistance. Molybdenum, nickel, and chromium are common alloying elements in stainless steel.
The producer’s selling price plus a surcharge added to offset the increasing costs of raw materials caused by increasing alloy prices.
Annealing (Solution Annealing)
A process of heating cold stainless steel to obtain maximum softness and ductility by heat treatment which also produces a homogeneous structure (in austenitic grades) or a 50/50 mixture of austenite and ferrite (in duplex grades). It relieves stresses that have built up during cold working and ensures maximum corrosion resistance. Annealing can produce scale on the surface that must be removed by pickling.
Polarization to a more oxidizing potential to achieve a reduced corrosion rate by the promotion of passivity.
Argon-Oxygen Decarburisation (AOD)
A process of further reducing the carbon content of stainless steel during refinement. AOD is closely related to Electric Arc Furnaces (EAF), but has a shorter operating time and requires lower temperatures.
Austenitic Stainless Steel
Non-magnetic stainless steels that contain nickel and chromium sufficient to develop and retain the austenitic phase at room temperature. Austenitic stainless steels are the most widely used category of stainless steel.
Automatic Gauge Control
A hydraulic roll force system where stainless steel makers can monitor a stainless steel sheet’s thickness while it moves through the mill. The computer’s gap sensor adjusts and monitors the thickness 50 to 60 times per second.
Stainless steel formed into long shapes from billets. They can be rounds, squares, hexagons, octagons or flats, either hot or cold finished.
Long pieces of squared-off metal, normally stainless steel, which is used in building construction.
Tests used to assess the ductility and malleability of stainless steel subjected to bending.
A semi-finished form of stainless steel that is used for long products such as bars and forgings. Billets are normally two to seven inches square.
A section of sheet stainless steel that has the outer dimensions of a specific part but has not yet been stamped by the end user. This lowers the stainless steel processor’s labour and transportation costs.
A semi-finished form of stainless steel that will be further processed into mill products. Generally having a cross-section greater than 36 sq. inches.
A hot rolling mill that takes continuously cast slabs or ingots and processes them into blooms.
Brazing and soldering are techniques for joining metals in the solid state by means of a fusible filler metal with a melting point well below that of the base metal.
The same as annealing but carried out in an atmosphere that prevents tarnishing
or scaling and therefore preserves the bright surface.
A fracture that has little or no plastic deformation.
A subtle ridge on the edge of strip stainless steel resulting from cutting operations such as slitting, trimming, shearing, or blanking. For example, as a stainless steel processor trims the sides of the sheet stainless steel parallel or cuts a sheet of stainless steel into strips, its edges will bend with the direction of the cut.
To shape molten metal by pouring into a mould to produce an ingot or a continuously cast slab.
Hardening a ferrous alloy to make the outside (case) much harder than the inside (core). This can be done carburizing, cyaniding, nitriding, carbonitriding, induction hardening, and flame hardening. Their application to stainless steel is limited wherever they decrease corrosion resistance.
Corrosion caused by a reaction of an amphoteric metal with the alkaline products of electrolysis.
A chemical substance that prevents or slows a cathodic or reduction reaction.
Reducing the corrosion of a metal by making the particular surface a cathode of an electrochemical cell.
The rapid formation and depletion of air bubbles that can damage the material at the solid/liquid interface under conditions of severe turbulent flow.
An operation whereby the surface of a bar is ground without using a lathe.
A report of the chemical composition of the elements, and their percentage that forms a stainless steel product.
The material that is loaded into an electric furnace that will melt into a composition that will produce a stainless molten product. Normally recycled scrap, iron, and alloying elements.
Chloride Stress Corrosion Cracking
Cracking due to the combination of tensile stress and corrosion in the presence of water and chlorides.
An alloying element that is used in stainless steel to deter corrosion.
Application of a stainless steel coating to a lower-alloy steel by means of pouring, welding, or coating to increase corrosion resistance at a lower cost than using steel exclusively.
A sheet of stainless steel that has been rolled into a coil to facilitate transportation and storage.
Cold Finished Bars
Hot rolled stainless steel bars that are annealed and cold worked to produce a higher surface quality and higher strength.
Cold Forming (Cold Working)
Any mechanical operation that creates permanent deformation, such as bending, rolling, drawing, etc. performed at room temperature that increases the hardness and strength of the stainless steel.
The process of rolling cold coils of a pickled hot-rolled sheet through a cold reduction mill to make the stainless steel stronger, thinner, and smoother by applying pressure.
Cold-Rolled Strip (Sheet)
Stainless steel that has been run through a cold reduction mill. The sheet is under 3/16th of an inch and 24″ wide and over. The strip is under 3/16 of an inch and under 24″ wide.
The physical use of stainless steel by end users. Consumption predicts changes in inventories, unlike demand figures.
Processes of pouring stainless steel into a billet, bloom, or slab directly from the furnace. This process avoids the need for large, expensive mills and also saves time because the slabs solidify in minutes rather than the several hours it takes it for an ingot to form.
Stainless steel customers demanding stainless steel in a more finished state such as tubing, pipe, and cold-rolled strip from re-rollers and tube makers.
The attack upon metals by chemical agents converting them to nonmetallic products. Stainless steel has a passive film created by the presence of chromium (and often other alloying elements, nickel, molybdenum) that resists this process.
Cracking due to repeating and fluctuating stresses in a corrosive environment.
The potential of a corroding surface in an electrolyte relative to a reference electrode under open-circuit conditions.
The rate at which an object corrodes.
A metal’s ability to resist corrosion in a particular environment.
A abbreviation for “cold rolled annealed and pickled.”
Strain caused by the stress that occurs over time.
Corrosion of stainless steel on the surface that is fully shielded from the air such that the passive film cannot be created to resist the corrosion.
Critical Pitting Potential
The lowest value of the oxidizing potential at which pits can form and grow. The value depends on the test method used.
Cutting flat-rolled stainless steel into the desired length and then normally shipped flat-stacked.
Removing the subtle ridge from the edge of strip metal that results from cutting operation such as slitting, trimming, shearing, or blanking.
A process that removes the oxide scale from the surface of the stainless steel that develops from hot operations.
A forming process that presses metal into or through a die (as in cold drawn wire).
To produce speciality tubing, this procedure uses a drawbench to pull tubing through a die and over a mandrel, allowing excellent control of the inside diameter and wall thickness.
A measurement of the malleability of stainless steel in terms of the amount of deformation it will withstand before failure.
Stainless steel comprised of austenitic and ferretic stainless steels that contain high amounts of chromium and nickel. This combination is stronger than both of the individual stainless steels. Duplex stainless steels are highly resistant to corrosion and cracking.
Edge Rolling (Edge Conditioning)
To facilitate customer manipulation, strips of stainless steel are rolled to smooth the edges and remove any burrs.
When stainless steel is bent, the metal towards the outside of the bend is in tension and the metal towards the inside is in compression. If the applied bending force is not sufficient to cause permanent plastic flow at either the inner or outer surfaces, the metal will return elastically to its original shape. Stainless steel has a greater elastic spring back than mild steel.
Electric Arc Furnace (EAF)
A stainless steel producing furnace where scrap generally makes up a high percentage of the charge. Heat is supplied from electricity that arcs from the electrodes to the metal bath. These furnaces may operate on AC or DC.
Electric Resistance Welded (ERW) Pipe
Pipe made from strips of hot-rolled stainless steel, which are passed through forming rolls and welded.
A measurement of ductility expressed in terms of the stretch having occurred over a given length on a standard tensile specimen at the time of fracture, usually based upon an original length of 2 inches.
A material’s loss of malleability due to chemical treatment or physical change.
The continuous depletion of a material due to mechanical interaction with a liquid, a multicomponent fluid, or solid particles carried with the fluid.
An accelerated loss of material concerning corrosion and erosion that results from corrosive material interacting with the material.
A shaped piece of stainless steel produced by forcing the bloom, bar, or rod through a die of the appropriate shape.
An intermediate product producer that purchases materials and processes them specifically for a particular project.
A condition leading to the eventual fracture of a material due to constant or repeated stresses that exert less pressure than the tensile strength of the material.
The body-centred cubic crystalline phase of iron-based alloys.
Magnetic stainless steels that have a low carbon content and contain chromium as the main alloying element, usually between 13% and 17%. It is the second most widely used stainless steel. Ferritic stainless steels are generally used in automotive trim and exhaust systems, hot water tanks, and interior architectural trim.
Metal products such as ferrochrome, ferromanganese, and ferrosilicon that are commonly used as raw materials to aid various stages in stainless steel making.
A common raw material in stainless steel production. This alloy consists of iron and up to 72% chromium.
Any metal that is primarily composed of iron.
The final condition of the surface after the last phase of production.
These facilities process semi-finished stainless steel into ready-made forms that can be used by others. Some facilities are rolling mills, pickle lines, tandem mills, annealing facilities, and temper mills.
Flat-Rolled Stainless Steel (Flat Product)
Category of stainless steel that includes shapes such as sheet, strip, and plate.
An iron cleaning agent that consists of limestone and lime. These products react with impurities in the metallic pool and float to the top of the liquid iron.
Metal with a maximum width of .005 inches.
Forming a hot or cold metal into a fixed shape by hammering, upsetting, or pressing.
A process that brings about a change in the shape of stainless steel by the application of force (i.e. cold forming, hot forming, wire forming).
An accumulation of marine organism deposits on a submerged metal surface. Fouling also refers to the accumulation of normally inorganic deposits on heat exchanger tubing.
A stainless steel to which a small amount of some relatively insoluble element (such as sulfur, selenium) is added to create a minute and widely distributed soft phase that acts as chip breakers during machining.
Deterioration at the interface of two contacting surfaces under load which is accelerated by their relative motion.
Accelerated corrosion of a metal because of an electrical contact with a more noble metal or nonmetallic conductor in a corrosive electrolyte.
(see edge rolling)
The thickness of a certain stainless steel.
“General corrosion” is the term used to describe the attack that proceeds in a relatively uniform manner over the entire surface of a metal. Typically stainless steels do not exhibit general corrosion.
Grain (Grain Boundary)
The individual crystal units comprising the aggregate structure where the crystalline orientation does not change. The grain boundary is where these individual crystal units meet.
A term that implies metal removal similar to fast milling where the surface is removed by abrasion.
An abbreviation for “hot rolled annealed and pickled.”
Hardness testing consists of pressing an indenter into a flat surface under a perfectly controlled load, then measuring the dimension of the resulting indentation. The three methods most commonly used for stainless steel are the Rockwell B, Rockwell C and Vickers tests. The higher the number, the harder the material.
A term referring to a batch of refined stainless steel; a charged oxygen or electric furnace full of stainless steel. A heat of stainless steel can be used to cast several slabs, billets, or blooms.
Heat-Affected Zone (HAZ)
The part of a metal that is not melted during cutting, brazing, or welding, but whose microstructure and physical properties are altered by these processes.
Altering the properties of stainless steel by subjecting it to a series of temperature changes. To increase the hardness, strength, or ductility of stainless steel so that it is suitable for additional applications.
Hot Band (Hot-Rolled Stainless Steel)
Stainless steel that has been rolled on a hot-strip mill. It can be sold directly to customers or further processed into other finished products.
Hot forming operations are used widely in the fabrication of stainless steel to take advantage of their lower resistance to shape change. High temperature reduces their yield strengths, and this results in a marked lowering of the force that is required to bring about plastic movement or flow from one shape to another. (hot rolling, hot stretching, etc.)
The absorption of hydrogen by a metal resulting in a loss of ductility.
Stepwise internal cracks that connect adjacent hydrogen blisters on different planes in the metal, or to the metal surface.
Hydrogen Stress Cracking
Cracking of a metal resulting from the combination of hydrogen and tensile stress.
Impact testing is used to measure the toughness of a material, corresponding to the energy necessary to cause fracture under shock loading. Low toughness is generally associated with brittle shear fracture and high toughness with ductile plastic tearing.
Semi-finished stainless steel that has been poured into moulds and then solidified. The moulds are then removed and the stainless steel is ready for rolling or forging.
Facilities that combine all the stainless steel making facilities from melt shop through hot rolling and cold finishing, to produce mill products.
Preferential corrosion cracking at or along the grain boundaries of a metal.
Intergranular Stress Corrosion Cracking
Stress corrosion cracking in which the cracking occurs along grain boundaries.
A mineral that contains enough iron to be a factor in stainless steel production.
These alloys are at the highest end of the range of temperature and strength. Additives such as chrome, nickel, titanium, manganese, molybdenum, vanadium, silicon, and carbon may be used. These superalloys are also referred to as “super chrome stainless steels.”
A machine that smoothes any physical deficiencies in the sheet before it is shipped to the customer.
Life Cycle Costing
An accounting method of costing where expenses are allocated over the life of the product. Life cycle costs are often lower for stainless steel than for alternatives despite a higher initial outlay, because stainless products generally last longer and require little maintenance.
Light-Gauge Stainless Steel
A very thin sheet of stainless steel that has either been temper rolled or passed through a cold reduction mill.
A pipe extending over long distances that transports oil, natural gas, and other fluids.
Category of stainless steel that includes rods, bars, and structural products that are described as long rather than flat.
Low-Carbon Stainless Steel
Stainless steel containing less than 0.03% carbon.
A hard supersaturated solid solution of iron characterized by an acicular (needle-like) microstructure.
A small category of magnetic stainless steels typically containing 12% chromium, a moderate level of carbon, and a very low level of nickel.
Mechanical Properties (Physical Properties)
Properties determined by mechanical testing, such as yield strength, ductility, ultimate tensile strength, hardness, bendability, impact strength, etc.
Generally mill forms of sheet, strip, plate, bar rod and semi-finished forms.
An alloying element that enhances corrosion resistance along with chromium in stainless steels.
An alloying element used in stainless steels to enhance ductility and corrosion resistance.
Alloy metal produced for high-performance, high-temperature applications such as nickel-iron-chrome alloys and nickel-chrome-iron alloys.
Metal or alloy that contains no iron.
Oil Country Tubular Goods (OCTG)
Category of pipe products used by petroleum exploration customers. Labels bearing OCTG are applied to casting, drill pipes, oil well tubing, etc.
An iron-containing material used primarily in the melting furnace.
A method of winding a narrow strip of stainless steel over a much wider roll. This allows for more stainless steel per roll and allows the customer to have longer processing runs.
Rust or corrosion due to exposure to oxygen.
When exposed in air, stainless steels passivate naturally (due to the presence of chromium). But the time required can vary. In order to ensure that the passive layer reforms rapidly after pickling, a passivation treatment is performed using a solution of nitric acid and water.
A characteristic condition of stainless steels which impedes normal corrosion tendencies to the point where the metal remains virtually un-attacked — hence passive to its environment.
A process that removes surface scale and oxidation products by immersion in a chemically active solution, such as sulfuric or hydrochloric acid.
A commercially available product that performs the pickling function when used on the surface of stainless steel.
A term that originally defined a tube used to transport fluids or gases. Often now, pipe and tube are used interchangeably.
Localized corrosion (in the form of pits) of a metal surface that is confined to a small area.
Stainless steel measuring more than ten inches wide with a thickness ranging from 3/16 of an inch and over.
Postweld Heat Treatment
Heating and cooling a weldment in such a way as to obtain desired properties.
Fabricating technique where fine metallic powder is compacted and heated under high pressure to solidify the material.
Precipitation Hardening (PH)
A small category of stainless steels resembling martensitic stainless steels that have great strength and hardness due to heat treatment.
A temporary adhesive protective film attached to the surface that protects the surface during forming and handling operations that are stripped before final use.
Reinforcing Bar (Rebar)
A commodity-grade stainless steel used to reinforce concrete in highway and building structures.
The impurities remaining in mini-mill stainless steels resulting from the wide variety of metals entering the process.
A stand of rolls that passes stainless steel back and forth between the rolls in order to reduce the stainless steel sheet or plate. The distance between the rolls is reduced after each pass.
Semi-finished stainless steel that is rolled from a billet and is commonly used for wire products, bolts, and nails.
Scale (Scale Removal)
The oxide that forms on the surface of stainless steel, after exposure to high temperature.
Iron-containing stainless steel material that is normally remelted and recast into new stainless steel. Home scrap is left over stainless steel generated from edge trimming and rejects within the mill. Also, industrial scrap that is trimmed by stampers and auctioned to buyers.
Pipe produced from a solid billet that is heated and rotated under pressure. This rotating pressure creates a hole in the middle of the billet, which is then formed into a pipe by a mandrel.
Secondary Stainless Steel
Stainless steel that has been rejected by an original customer because of a defect in the chemistry, gauge, or surface quality. Mills then search for another customer that will accept the stainless steel at a discount.
Semi-Finished Stainless Steel
Stainless steel products such as blooms, billets, or slabs that are then rolled and processed into beams, bars, sheets, etc.
The phenomenon in austenitic stainless steels that causes a change to occur in the grain boundaries when heated in the general range of 850 to 1475 degree F. This change destroys the passivity in these locations.
An operation that buys metal, stores it, (often processing it in some way) and then sells it in a slightly different form than it was purchased from the producing mills.
Levellers, edge trimmers, and temper mills reshape processed stainless steel to meet customers’ specifications. Reshaping is needed from processes that cause deformities in the stainless steel.
Trimming of the edges of sheet strip to make them parallel. This done at either the stainless steel mill or at the stainless steel processor.
A stainless steel flat-rolled product that is under 3/16 inches in thickness and 24 inches and over in width.
Blast cleaning using stainless steel shot as the abrasive. Not recommended for stainless steel. Glass beads should be used.
An extremely brittle Fe-Cr phase that can form at elevated temperatures in austenitic and ferritic stainless steels.
A very common type of semi-finished stainless steel usually measuring 6-10 inches thick by 30-85 inches wide and average 20 feet long. After casting, slabs are sent to a strip mill where it is rolled and coiled into sheet and plate products.
The impurities in a molten pool of iron. Flux may be added to congregate the impurities into a slag. Slag is lighter than iron and will float allowing it to be skimmed.
Cutting a sheet of stainless steel into a smaller strip to meet customers demands.
Solution Heat Treatment
Heating a metal to a high temperature and maintaining it long enough for one or more constituents to enter the solid solution. The solution is then cooled rapidly to retain the constitutes within.
The removal of contaminants such as oil, grease, dirt, salts, etc. by cleaning with a solvent, steam, vapour, alkali, or emulsion.
Metals with distinct chemical and physical properties. These alloys are produced for very specific applications; considered to be on the low end of superalloys.
Category of steel that includes electric, alloy, stainless, and tool steels.
A wide variety of high quality, specialized tubular products. It is usually found in the automotive and agricultural industries, construction equipment, hydraulic cylinders, etc.
Group of corrosion resistant steels containing at least 10.5% chromium and may contain other alloying elements. These steels resist corrosion and maintain its strength at high temperatures.
A reversing stainless steel sheet reduction mill with heated coil boxes at each end. Stainless steel sheet or plate is sent through the rolls of the reversing mill and coiled at the end of the mill, reheated in the coil box, and sent back through the Steckel stands and recoiled. By reheating the stainless steel prior to each pass, the rolls can squeeze the stainless steel thinner per pass and impart a better surface finish.
The amount of elongation, force, or compression that occurs in a metal at a given level of stress. Generally in terms of inches elongation per inch of material.
The ability of stainless steel to oppose applied forces when considering resistance to stretching, forming, compressing, etc.
Stress Corrosion Cracking (SCC)
Slowly developing cracks that form in stainless steel due to mechanical stress and exposure to a corrosive environment.
A stainless steel flat-rolled product that is under 3/16 inches and is under 24 inches in width.
An architectural stainless steel product group that includes I-beams, H-beams, wide-flange beams and sheet piling. These products are used in multi-story buildings, bridges, vertical highway supports, etc.
Lightweight metal alloys designed specifically to withstand extreme conditions. Conventional alloys are iron-based, cobalt-based, nickel-based, and titanium-based.
A section of sheet stainless steel that is cut to the manufacturer’s desire. Excess stainless steel is trimmed away to save transportation costs and is ready for the stamper to shape with a die press.
A cold-rolling mill that gives greater strength, a more uniform and smoother surface, and a reduced thickness to the stainless steel sheet. This mill rolls stainless steel through a series of rolls, to achieve the desired thickness and surface quality.
A by-product of tin processing, this refractory metal is used as a barrier to corrosion of chemical processing and carbide cutting tools, and still-growing use as electronic capacitors and filaments. Melts at 2415 degrees Fahrenheit.
A term applied to a cold worked material such as strip, sheet, wire, expressing the range of mechanical properties as produced by the cold work (as is quarter hard,
half hard, etc.).
A very ductile and malleable white metal that is used in aviation, aerospace, etc. because of its high strength and lightweight.
Lightweight, corrosive-resistant alloys suitable for high temperatures. These alloys are very practical for aeroplane parts. Titanium alloys can be blended with aluminium, iron, vanadium, silicon, cobalt, tantalum, zirconium, and manganese.
Tool Stainless Steels
Hardened stainless steels that are used in the manufacturing of tools and dies.
Unit of measure for stainless steel scrap and iron ore.
Gross Ton: 2,240 pounds.
Long (net) Ton: 2,240 pounds.
Short (net) Ton: 2,000 pounds. Normal unit of statistical raw material input and stainless steel output in the United States.
Metric ton: 1,000 kilograms. (2,204.6 pounds or 1.102 short tons).
When referring to OCTG, tubing is a separate pipe used within the casing to conduct the oil or gas to the surface. Depending on conditions and well life, the tubing may have to be replaced during the operational life of a well.
Gray metal with high tensile strength. It is ductile, malleable, and resistant to atmospheric elements and all acids except strong alkalies.
Vacuum Oxygen Decarburisation (VOD)
A refinement of stainless steel that reduces carbon content. Molten, unrefined stainless steel is heated and stirred by an electrical current while oxygen enters from the top. Many undesirable gases escape from the stainless steel and are evacuated by a vacuum pump. Alloys and other additives are then mixed in to refine the molten stainless steel further.
A grey metal that is normally used as an alloying agent for iron and stainless steel. It is also used as a strengthener of titanium-based alloys.
The lateral dimensions of rolled stainless steel, as opposed to the length or the gauge. If the width of the stainless steel strip is not controlled during rolling, the edges must be trimmed.
A cold finished stainless steel product (normally in coils) that is round, square, octagon, hexagon and flats under 3/16 inches.
The stress beyond which stainless steel undergoes important permanent flow — commonly specified as that stress producing a 0.2% offset from the linear portion of the stress-strain curve.
A strong, ductile metal obtained by the chemical processing of zircon-bearing sands. It has good corrosion resistance at high temperatures and is used as a structural material in nuclear reactors and cladding material for uranium.