Glossary of Steel Terms

Steel Terms Explained.

Below we list some of the most common steel terms and explain what they mean.

AISIAbbreviation for the American Iron and Steel Institute.
AlloyTwo or more chemical elements, of which one at least is metal.
Alloy SteelA steel containing more than one alloying element.
AnnealingA process to soften steel and remove any stresses. The process usually involves heating the steel in a furnace and allowing to cool slowly.
ASTMAbbreviation for the American Society for Testing and Materials, now known as ASTM International.
AusteniticA range of stainless steels which have austenite as their primary phase, with a face centred cubic crystal structure. Commonly these are 18/8 stainless steel types with an average composition of 18% chromium and 8% nickel.
BarSteel is rolled or forged from billet into long lengths in round, flat, square and hexagon bar.
Brinell (HB)A measurement of the surface hardness of a steel.
Bright DrawnA ‘bright drawn’ steel is produced by drawing steel bar through a die without pre heating to obtain a smooth finish with tight tolerances.
Carbon SteelA steel with key components of carbon, silicon and manganese but normally has no or very low content of other alloying elements.
Case HardeningA heat treatment process for steel, usually low carbon steel and alloy steel grades. The process hardens the outside case of the steel by infusing elements in the steel surface, whilst giving good strength to the steel core. Also known as carburising or surface hardening.
Cast IronAn alloy of iron that contains a carbon content of between 1.8% to 4.5%, combined with silicon and manganese. Cast Iron is more brittle than steel and has a lower melting temperature.
Centreless GrindingThe method of finishing round steel bar by removing the surface with a grinding wheel. Centreless ground steel bar is produced to very tight tolerances.
Charpy TestA charpy test measures the amount of energy absorbed by a steel during fracture.
CreepA metal failure caused by elongation due to continuous stress.
DIN StandardsCommonly referring to DIN steel specifications introduced by Deutsches Institut für Normung in Germany. DIN steel standards are combination of letters and numbers.
DuplexDuplex is a stainless steel with an austenitic ferritic chromium, nickel, molybdenum composition. Duplex combines improved resistance to stress corrosion cracking, pitting, crevice corrosion and offers high strength when compared with other stainless alloys.
Electric Arc FurnaceA steel furnace that uses an electric arc to generate heat. After melting the steel is commonly cast into blooms, slabs or billets.
FerrousAny steel, metal or alloy which is primarily made up of iron.
FatigueProgressive and structural damage which occurs when a steel is subjected to repeated cyclic stressing or loading.
Flame CuttingA process used to cut carbon steel plate using an oxy-fuel gas flame.
ForgingA process of shaping or forming steel by using compressive forces such as hammering, upsetting, rolling or pressing.
GradeThe name and designation of a steel defined by its composition and properties.
HardeningA process used to increase the hardness of steel. The process usually requires heating, quenching, tempering and cooling.
HardnessThe hardness of a steel is measured by its ability to resist surface penetration. Common measurements of hardness include Rockwell, Brinell and Vickers.
Heat TreatmentA process to change the mechanical properties of a steel. Typical heat treatment processes are hardening, annealing, normalising and nitriding.
High Carbon SteelUsually a steel suited to heat treatment with a minimum of 0.5% carbon content.
High Speed SteelHigh Speed Steel has more advantages to the standard tool steel grades offering high hardness at temperature and high wear resistance.
ImpactImpact testing measures energy absorption by fracturing a steel test bar at high velocity.
Lumsden GrindingThe method of finishing steel plate by removing the surface with a reciprocating or rotary grinding machine.
Manganese SteelCommonly referring to the 11% to 14% manganese steel plate. A work hardening steel that becomes increasingly hard when the surface is subject to repeated abrasion or impact.
MartensiticA range of stainless steel grades which are magnetic and can be hardened and tempered.
Mechanical PropertiesSteels can achieve different measurements of strength, toughness and hardness, dependent on composition and heat treatment – commonly known as the mechanical properties of steel.
MeehaniteA continuous cast iron type material.
Modulus of ElasticityA measurement of the resistance of a steel to be deformed elastically and how it will restore it to its original shape after distortion.
Non Ferrous MetalA metal or alloy that has no iron content.
NormalisingA heat treatment process to remove stresses from steel, often used after flame cutting of higher carbon steel grades. The steel is heated and held at a temperature above its upper critical limit for a designated amount of time and then allowed to cool in air.
OxidationWhen a steel is exposed to oxygen, commonly atmospheric conditions it may oxidise giving the surface a stain, discolouration or rust.
Physical PropertiesRelating to the physics of a steel rather than mechanical properties, usually include such properties as density, coefficient of thermal expansion and electrical conductivity.
Plasma CuttingA process used to cut stainless steel plate using a plasma torch. An inert gas is blown at high speed through a nozzle forming an electrical arc which forms a hot plasma for penetrating and cutting.
Precipitation HardeningCommonly a heat treatment process for certain types of stainless steel, in which a constituent precipitates from a supersaturated solid solution. Also known as age hardening.
Precision GrindingThe method of finishing steel plate by removing the surface with a surface grinding machine, to achieve tight tolerances.
QuenchingA heat treatment term where a steel is rapidly cooled after heating (common cooling mediums include oil, water and air)
RockwellA measurement of the surface hardness of a steel.
Spheroidal Graphite IronA ductile cast iron, commonly known as S G Iron.
Spring SteelA medium to high carbon steel or an alloy or stainless steel which, when heat treated, has a high yield strength.
Stainless SteelHighly alloyed steel grades giving good resistance to corrosion and oxidation.
SteelAn iron based alloy containing various quantities of carbon, silicon, manganese and other elements.
Steel AnalysisThe chemical composition and make up of a steel specification.
Steel ElementsA steel element is a pure chemical substance defined by its atomic number (the number of protons in its nucleus).
TemperingA heat treatment term where a steel is re heated to a desired temperature after quenching and allowed to cool to give the required hardness or mechanical properties.
Tensile StrengthA measurement of the maximum load per unit a steel test piece will achieve before fracturing.
Tolerances (of steel bar and plate)The tolerance is the permissible limits or limits of variation from a specified dimension.
Tool SteelCommonly steels that are suitable for heat treatment to a high hardness, which offer good tooling characteristics such as abrasion resistance and ability to hold a cutting edge. Tool steel types include cold work tool steel, hot work tool steel and plastic mould tool steel.
Tool Steel Brand NamesCommonly referring to tool steel producers of old who give a steel specification its own company brand name.
UNSAbbreviation for ‘unified numbering system’.
WerkstoffGerman steel specifications commonly shown as a number followed by a full stop then four more numbers (i.e. 1.2379).
Yield StrengthThe yield strength or yield stress of a steel relates to the level of stress in steel where plastic deformation commences.