Steel Terminology

Alloy steel: a steel, other than a stainless steel, that conforms to a specification that requires one or more of the following elements, by mass percent, to have a minimum content equal to or greater than: 0.30 for aluminum; 0.0008 for boron; 0.30 for chromium; 0.30 for cobalt; 0.06 for columbium (niobium); 0.40 for copper; 0.40 for lead; 1.65 for manganese; 0.08 for molybdenum; 0.30 for nickel; 0.60 for silicon; 0.05 for titanium; 0.30 for tungsten (wolfram); 0.10 for vanadium; 0.05 for zirconium; or 0.10 for any other alloying element, except sulphur, phosphorus, carbon, and nitrogen.

Annealing: a generic term covering any of several heat treatments.

Capped steel: n—a rimmed steel in which, during ingot solidification, the rimming action was limited by mechanical or chemical means.

Carbon steel: n—a steel that conforms to a specification that prescribes a maximum limit, by heat analysis in mass percent, of not more than: 2.00 for carbon and 1.65 for manganese, but does not prescribe a minimum limit for chromium, cobalt, columbium (niobium), molybdenum, nickel, tungsten (wolfram), vanadium, or zirconium.

Certificate of compliance: n—in manufactured products, a document that states that the product was manufactured, sampled, tested, and inspected in accordance with the requirements of the specification (including year of issue) and any other requirements specified in the purchase order or contract, and has been found to meet such requirements.

Cold working: n—mechanical deformation of a metal at temperatures below its recrystallization temperature.

Cold treatment: exposing a steel object to temperatures below room temperature for the purpose of obtaining desired conditions or properties, such as dimensional or structural stability.

Conditioning heat treatment: a preliminary heat treatment used to prepare a steel object for a desired reaction to a subsequent heat treatment.

Controlled cooling: cooling a steel object from an elevated temperature in a predetermined manner to avoid hardening, cracking, or internal damage, or to produce a desired microstructure or mechanical properties.

Cyaniding: introducing carbon and nitrogen into a solid steel object by holding it above The transformation temperature (Ac1) in contact with molten cyanide of suitable composition.

Direct quenching: in thermochemical processing, quenching immediately following the thermochemical treatment.

Flame annealing: annealing in which the heat is applied directly by a flame.

Flame hardening: a process in which only the surface layer of a suitable steel object is heated by flame to above Ac3 or Accm, and then the object is quenched.

Full annealing: annealing a steel object by austenitizing it and then cooling it slowly through the transformation range.

Graphitization annealing: annealing a steel object in such a way that some or all of the carbon is precipitated as graphite.

Hardening: increasing the hardness by suitable treatment, usually involving heating and cooling.

Heat treatment: heating and cooling a steel object in such a way as to obtain desired conditions or properties.

Killed steel: n—steel deoxidized to such a level that essentially no reaction occurred between carbon and oxygen during solidification.

Homogenizing: holding a steel object at high temperature to eliminate or decrease chemical segregation by diffusion.

Hot quenching: n—an imprecise term used to cover a variety of quenching procedures in which the quenching medium is maintained at a prescribed temperature above 160°F or 70°C.

Induction hardening: n—in surface hardening, a process in which only the surface layer of a suitable steel object is heated by electrical induction to above Ac3 or Accm, and then the object is quenched.

Induction hardening: n—in through hardening, a process in which a suitable steel object is heated by electrical induction to above Ac3 or Accm throughout its section, and then the object is quenched.

Induction heating: n—heating by electrical induction.

Intermediate annealing: n—annealing wrought steel objects at one or more stages during manufacture prior to final thermal treatment.

Interrupted aging: n—aging at two or more temperatures, by steps, and cooling to room temperature after each step.

Interrupted quenching: n—quenching in which the object being quenched is removed from the quenching medium while the object is at a temperature substantially higher than that of the quenching medium.

Isothermal annealing: n—austenitizing a steel object and then cooling it to, and holding it at, a temperature at which austenite transforms to a ferrite-carbide aggregate.

Isothermal transformation: n—a change in phase at any constant temperature.

Low-steel/" target="_blank" class="keylink">alloy steel: n—a steel, other than a carbon steel or an interstitial-free steel, that conforms to a specification that requires the minimum content for each specified alloying element to be lower than the applicable limit in the definition for steel/" target="_blank" class="keylink">alloy steel.

Maraging: n—a precipitation hardening treatment applied to a special group of steel/" target="_blank" class="keylink">alloy steels to precipitate one or more intermetallic compounds in a matrix of essentially carbon free martensite.

Martempering, n—quenching an austenitized steel object in a medium at a temperature in the upper part of, or slightly above, the martensite range, holding it in the medium until its temperature is substantially uniform throughout, and then cooling it in air through the martensite range.

Martensite range: n—the temperature interval between Ms and Mf.

Natural aging: n—spontaneous aging of a super-saturated solid solution at room temperature.

Nitriding: n—introducing nitrogen into a solid steel object by holding it at a suitable temperature in contact with a nitrogenous environment.

Normalizing: n—heating a steel object to a suitable temperature above the transformation range and then cooling it in range.

Overaging: n—aging under conditions of time and temperature greater than those required to obtain maximum change in a certain property, so that the property is altered away from the maximum.

Overheating: n—heating a steel object to such a high temperature that excessive grain growth occurs.

Patenting: n—in wire making, heating a medium-carbon or high-carbon steel before wire drawing, or between drafts, to a temperature above the transformation range, and then cooling it in air, or a bath of molten lead or salt, to a temperature below Ae1.

Post-weld heat treatment: n—heating weldments immediately after welding, to provide tempering, stress relieving, or a controlled rate of cooling to prevent formation of a hard or brittle microstructure.

Precipitation hardening: n—hardening caused by the precipitation of a constituent from a supersaturated solid solution.

Precipitation heat treatment: n—artificial aging in which a constituent precipitates from a supersaturated solid solution.

Preheating: n—for steel/" target="_blank" class="keylink">tool steels, heating to an intermediate temperature immediately before final austenitizing.

Preheating: n—heating before welding, a mechanical treatment, or some further thermal treatment.

Process annealing: cooling it, in order to soften it for further cold working.

Progressive aging: n—aging by increasing the temperature in steps, or continuously, during the aging cycle.

Quench aging: n—aging associated with quenching after solution heat treatment.

Quench annealing: n—annealing an austenitic steel object by solution heat treatment.

Quench hardening: n—hardening a steel object by austenitizing it, and then cooling it rapidly enough that some or all of the austenite transforms to martensite.

Quenching: n—rapid cooling.

Recrystallization: n—the formation of a new grain structure through a nucleation and growth process.

Recrystallization annealing: n—annealing a cold-worked steel object to produce a new grain structure without a change in phase.

Recrystallization temperature:, n—the approximate minimum temperature at which recrystallization of a cold-worked steel object occurs within a specified time.

Secondary hardening: n—the hardening phenomenon that occurs during high-temperature tempering of certain steels containing one or more carbide-forming alloying elements.

Selective heating: n—intentionally heating only certain portions of a steel object.

Selective quenching: n—quenching only certain portions of a steel object.

Shell hardening: n—a surface hardening process in which a suitable steel object, when heated through and quench hardened, develops a martensitic layer or shell that closely follows the contour of the piece and surrounds a core of essentially pearlitic transformation product.

Slack quenching: n—the incomplete hardening of a steel object due to quenching from the austenitizing temperature at a rate slower than the critical cooling rate for the particular steel composition, resulting in the formation of one or more transformation products in addition to martensite.

Snap temper: n—a precautionary interim stress-relieving treatment applied to a high-hardenability steel immediately after quenching to prevent cracking because of delay in tempering it at the prescribed higher temperature.

Soaking: n—prolonged holding at a selected temperature.

Solution heat treatment: n—heating a steel object to a suitable temperature, holding it at that temperature long enough to cause one or more constituents to enter into solid solution, and then cooling it rapidly enough to hold such constituents in solution.

Spray quenching: n—quenching in a spray of liquid.

Stabilizing treatment: n—any treatment intended to stabilize the microstructure or dimensions of a steel object.

Strain aging: n—aging induced by cold working.

Stress relieving: n—heating a steel object to a suitable temperature, holding it long enough to reduce residual stresses, and then cooling it slowly enough to minimize the development of new residual stresses.

Subcritical annealing: n—annealing at a temperature slightly below Ac1.

Surface hardening: n—a generic term covering any of several processes that, by quench hardening only, produce in a steel object a surface layer that is harder or more wear resistant than the core.

Tempering: n—reheating a quench hardened or normalized steel object to a temperature below Ac1, and then cooling it at any desired rate.

Thermochemical treatment: n—a heat treatment carried out in a medium suitably chosen to produce a change in the chemical composition of the steel object by exchange with the medium.

Time quenching: n—interrupted quenching in which the duration of holding in the quenching medium is controlled.

Transformation ranges: n—those range of temperature within which austenite forms during heating and transforms during cooling.

Transformation temperature: n—the temperature at which a change in phase occurs, with the limiting temperatures of the transformation ranges designated using the following symbols:

Accm—the temperature at which the solution of cementite in austenite is completed during heating.

Ac1—the temperature at which austenite begins to form during heating.

Ac3—the temperature at which transformation of ferrite to austenite is completed during heating.

Ac4—the temperature at which austenite transforms to delta ferrite during heating. Ae1, Ae3, Aecm,

Ae4—the temperatures of phase change at equilibrium.

Arcm—the temperature at which precipitation of cementite starts during cooling.

Ar1—the temperature at which transformation of austenite to ferrite or to ferrite plus cementite is completed during cooling.

Ar3—the temperature at which austenite begins to transform to ferrite during cooling.

Ar4—the temperature at which delta ferrite transforms to austenite during cooling.

Mf—the temperature at which transformation of austenite to martensite is substantially completed during cooling.

Ms—the temperature at which transformation of austenite to martensite starts during cooling.

Defect: n—an imperfection of sufficient magnitude to warrant rejection based on the specified requirements.

Quenching: immediately following the final hot deformation.

Grain size: n—the dimensions of the grains or crystals in a polycrystalline metal, exclusive of twinned regions and subgrains when present.

Heat: n—a generic term denoting a specific lot of steel, based upon steelmaking and casting considerations.

Heat analysis: n—the chemical analysis determined by the steel producer as being representative of a specific heat of steel.

Heat number: n—the alpha, numeric, or alphanumeric designator used to identify a specific heat of steel.

High-strength low-steel/" target="_blank" class="keylink">alloy steel: n—a steel, other than a carbon  steel or an interstitial-free steel, that conforms to a specification that requires the minimum content for each specified alloying element to be lower than the applicable limit in the definition for steel/" target="_blank" class="keylink">alloy steel, and the yield point or yield strength of the product to be at least 36 ksi or 250 MPa.

Hot-cold working: n—the mechanical deformation of austenitic and precipitation hardening steels at a temperature just below the recrystallization temperature to increase the yield strength and hardness by plastic deformation or precipitation hardening effects induced by plastic deformation, or both.

Hot working: n—mechanical deformation of a metal at temperatures above its recrystallization temperature.

Primary heat: n—the product of a single cycle of a batch melting process.

Remelted heat: n—the product of the remelting of a primary heat, in whole or in part.

Rimmed steel: n—a steel that contained sufficient oxygen to generate carbon monoxide at the boundary between the solid metal and the remaining molten metal during solidification, resulting in an outer layer low in carbon.

Semikilled steel: n—an incompletely deoxidized steel that contained sufficient oxygen to form enough entrapped carbon monoxide during solidification to offset solidification shrinkage.

Stainless steel: n—a steel that conforms to a specification that requires, by mass percent, a minimum chromium content of 10.5 or more, and a maximum carbon content of less than 1.20.

Steel: n—a material that conforms to a specification that requires, by mass percent, more iron than any other element and a maximum carbon content of generally less than 2.

Strain hardening: n—an increase in hardness and strength of a metal caused by plastic deformation at temperatures below its recrystallization temperature. (Syn. work hardening)

Test report: n—a document that presents the applicable qualitative or quantitative results obtained by applying one or more given test methods.
 

Abbreviated terms

COWH        Combination helical welding process for pipe during manufacturing

COWL        Combination longitudinal welding process for pipe during manufacturing

CTOD         Crack tip opening displacement

CVN            Charpy V-notch

CW            Continuous welding process for pipe during manufacturing

DWT           Drop-weight tear

EDI             Electronic data interchange

EW             Electric resistance or electric induction welding process for pipe during manufacturing

HAZ            Heat-affected zone

HBW           Brinell hardness

HFW           High-frequency electric welding process for pipe during manufacturing

HIC             Hydrogen-induced cracking

HRC            Rockwell hardness, C scale

HV              Vickers hardness

IQI              Image quality indicator

LFW           Low-frequency electric welding process for pipe during manufacturing

LPI             Liquid penetrant

LW             Laser welding process for pipe during manufacturing

MPI            Magnetic particle

NDE            Non-destructive examination 

NDT            Non-destructive testing

PSL            Product specification level

RI               Radiographic

SAWH        Submerged-arc helical welding process for pipe during manufacture

SAWL        Submerged-arc longitudinal welding process for pipe during manufacture

SSC           Sulfide stress cracking

SWC          Step-wise cracking

TFL            Through the flow line

T2,T3          Radiographic film classification

UI               Ultrasonic

USC            United States customary