Metallurgy glossary

Abrasive

Small particles of material that are propelled at high velocity to impact a surface during abrasive blast cleaning.

Abrasive Blast Cleaning

Cleaning and roughening of a surface produced by the high-velocity impact of an abrasive that is propelled by the discharge of pressurized fluid from a blast nozzle or by a mechanical device such as a centrifugal blasting wheel. (Also referred to as Abrasive Blasting.)

Acid

A substance which releases hydrogen ions when dissolved in water. Most acids will dissolve the common metals and will react with a base to form a neutral salt and water.

Active

The negative direction of electrode potential. (2) A state of a metal that is corroding without significant influence of reaction product.

Alkali

A group of water soluble mineral compounds, usually considered to have moderate strengths as bases (as opposed to the caustic or strongly basic hydroxides, although this differentiation is not always made). In general, the term is applied to bicarbonate and carbonate compounds when they are present in the water or solution.

Amphoteric Metal

A metal that is susceptible to corrosion in both acid and alkaline environments.

Anaerobic

Free of air or un-combined oxygen.

Anion

A negatively charged ion that migrates through the electrolyte toward the anode under the influence of a potential gradient.

Annealing

A heat treatment that softens metal and relieves internal stress by heating to an appropriate temperature then cooling at a controlled rate, improving ductility and machinability. *

Anode

The electrode of an electrochemical cell at which oxidation occurs. Electrons flow away from the anode in the external circuit. Corrosion usually occurs and metal ions enter the solution at the anode.

Anode Corrosion Efficiency

The ratio of the actual corrosion (mass loss) of an anode to the theoretical corrosion (mass loss) calculated from the quantity of electricity that has passed between the anode and cathode using Faraday’s law.

Anodic Inhibitor

A chemical substance that prevents or reduces the rate of the anodic or oxidation reaction.

Anodic Polarization

The change of the electrode potential in the noble (positive) direction caused by current across the electrode/electrolyte interface. [See Polarization.]

Anodic Protection

Polarization to a more oxidizing potential to achieve a reduced corrosion rate by the promotion of passivity.

Antifouling

Preventing fouling.

Atmospheric Corrosion

The gradual degradation or alteration of a material by contact with substances present in the atmosphere, such as oxygen, carbon dioxide, water vapour, and sulphur and chlorine compounds.

Austenitic Steel

A steel whose microstructure at room temperature consists predominantly of austenite.

Barrier Coating

(1) A coating that has a high resistance to permeation of liquids and/or gases. (2) A coating that is applied over a previously coated surface to prevent damage to the underlying coating during subsequent handling

Beach Marks

The characteristic markings on the fracture surfaces produced by fatigue crack propagation (also known as clamshell marks, conchoidal marks, and arrest marks).

Brittle Fracture

Fracture with little or no plastic deformation.

Carbon Steel

(1) Alloy of carbon and iron containing up to 2% carbon and up to 1.65% manganese and residual quantities of other elements, except those intentionally added in specific quantities for de-oxidation (usually silicon and/or aluminium). (2) An iron-based alloy containing carbon (usually less than 2.0%) and manganese (usually not less than 0.25%) with no specified minimum quantity for any alloying element other than manganese, silicon, and copper, and that contains only an incidental amount of any element other than carbon, silicon, manganese, copper, sulphur, and phosphorus.

Carburizing

The absorption and diffusion of carbon into iron or an iron-based alloy in contact with a suitable carbonaceous environment at elevated temperature.

Case Hardening

Hardening a ferrous alloy so that the outer portion, or case, is made substantially harder than the inner portion, or core. Typical processes are carburizing, cyaniding, carbo-nitriding, nitriding, induction hardening, and flame hardening.

Casting

Metal that is obtained at or near its finished shape by the solidification of molten metal in a mold.

Cathode

The electrode of an electrochemical cell at which reduction is the principal reaction. Electrons flow toward the cathode in the external circuit.

Cathodic Corrosion

Corrosion resulting from a cathodic condition of a structure, usually caused by the reaction of an amphoteric metal with the alkaline products of electrolysis.

Cathodic Inhibitor

A chemical substance that prevents or reduces the rate of the cathodic or reduction reaction.

Cathodic Polarization

The change of the electrode potential in the active (negative) direction caused by current across the electrode/electrolyte interface.

Cathodic Protection

A technique to reduce the corrosion of a metal surface by making that surface the cathode of an electrochemical cell.

Cation

A positively charged ion that migrates through the electrolyte toward the cathode under the influence of a potential gradient.

Cavitation

The formation and rapid collapse of cavities or bubbles within a liquid which often results in damage to a material at the solid/liquid interface under conditions of severe turbulent flow.

Cementation

The introduction of one or more elements into the surface layer of a metal by diffusion at high temperature. (Examples of cementation include carburizing [introduction of carbon], nitriding [introduction of nitrogen], and chromizing [introduction of chromium].)

Cementite

Microstructural constituent of steels composed of iron carbide (Fe3C).

Charpy Impact Test

A pendulum test measuring the energy absorbed by a notched specimen on fracture, used to assess toughness, often at sub-zero temperatures. *

Chevron Pattern

A V-shaped pattern on a fatigue or brittle-fracture surface. The pattern can also be one of straight radial lines on cylindrical specimens.

Chloride Stress Corrosion Cracking

Cracking of a metal under the combined action of tensile stress and corrosion in the presence of chlorides and an electrolyte (usually water).

Cold Working

Deforming metal plastically under conditions of temperature and strain rate that induce strain hardening, usually, but not necessarily, conducted at room temperature.

Compressive Strength

The maximum compressive stress a material is capable of withstanding without fracture or excessive flattening based on the load applied to its original cross-sectional area.

Conductivity

(1) A measure of the ability of a material to conduct an electric charge. It is the reciprocal of resistivity. (2) The current transferred across a material (e.g., coating) per unit potential gradient.

Corrosion

The deterioration of a material, usually a metal, that results from a reaction with its environment.

Corrosion Fatigue

Fatigue-type cracking of metal caused by repeated or fluctuating stresses in a corrosive environment characterized by shorter life than would be encountered as a result of either the repeated or fluctuating stress alone or the corrosive environment alone.

Corrosion Inhibitor

A chemical substance or combination of substances that, when present in the environment, prevents or reduces corrosion.

Corrosion Potential (ECORR)

The potential of a corroding surface in an electrolyte relative to a reference electrode under open-circuit conditions (also known as rest potential, open-circuit potential, or freely corroding potential).

Corrosion Rate

The rate at which corrosion proceeds.

Corrosion Resistance

Ability of a material, usually a metal, to withstand corrosion in a given system.

Corrosiveness

The tendency of an environment to cause corrosion.

Creep

Time-dependent strain occurring under stress.

Creep Strength

That stress which, when applied to a material at a specific elevated temperature, will cause a specified amount of elongation.

Crevice Corrosion

Localized corrosion of a metal surface at, or immediately adjacent to, an area that is shielded from full exposure to the environment because of close proximity of the metal to the surface of another material.

Critical Humidity

The relative humidity above which the atmospheric corrosion rate of some metals increases sharply.

Critical Pitting Potential (EP, EPP)

The lowest value of oxidizing potential (voltage) at which pits nucleate and grow. The value depends on the test method used.

Current

(1) A flow of electric charge. (2) The amount of electric charge flowing past a specified circuit point per unit time, measured in the direction of net transport of positive charges. (In a metallic conductor, this is the opposite direction of the electron flow.)

Current Density

The current to or from a unit area of an electrode surface.

Dealloying

The selective corrosion of one or more components of a solid solution alloy

Dendrite

A crystal that has a treelike branching pattern, being most evident in cast metals, slowly cooled through the solidification range.

Deposit Attack

Corrosion occurring under or around a discontinuous deposit on a metallic surface (also known as poultice corrosion).

Dezincification

A corrosion phenomenon resulting in the selective removal of zinc from copper-zinc alloys. (This phenomenon is one of the more common forms of de-alloying.)

Differential Aeration Cell

An electrochemical cell, the electromotive force of which is due to a difference in air (oxygen) concentration at one electrode as compared with that at another electrode of the same material.

Dissimilar Metals

Different metals that could form an anode-cathode relationship in an electrolyte when connected by a metallic path.

Ductility

The ability of a material to withstand significant plastic deformation prior to fracture. (It is often measured by the elongation or reduction in the cross-sectional area of a tensile test specimen.)

Duplex Stainless Steel

Stainless steel whose microstructure at room temperature consists primarily of a mixture of austenite and ferrite (also called <a title="Austenitic Stainless Steels" href="https://www.langleyalloys.com/materials/stainless/">austenitic/ferritic stainless steel</a>).

Elastic Deformation

Changes of dimensions of a material upon the application of a stress within the elastic range. Following the release of an elastic stress, the material returns to its original dimensions without any permanent deformation.

Elastic Limit

The maximum stress to which a material may be subjected without retention of any permanent deformation after the stress is removed.

Elasticity

The property of a material that allows it to recover its original dimensions following deformation by a stress below its elastic limit.

Electric Arc Furnace

An economical method of steel making that is energized by an electric arc flowing between two bottom electrodes. Furnace charges consist of purchased scrap.

Electrical Isolation

The condition of being electrically separated from other metallic structures or the environment.

Electrochemical Cell

A system consisting of an anode and a cathode immersed in an electrolyte so as to create an electrical circuit. The anode and cathode may be different metals or dissimilar areas on the same metal surface.

Electrode

A conductor used to establish contact with an electrolyte and through which current is transferred to or from an electrolyte.

Electrode Potential

The potential of an electrode in an electrolyte as measured against a reference electrode. (The electrode potential does not include any resistance losses in potential in either the electrolyte or the external circuit. It represents the reversible work to move a unit of charge from the electrode surface through the electrolyte to the reference electrode.)

Electrolyte

A chemical substance containing ions that migrate in an electric field.

Embrittlement

Loss of ductility of a material resulting from a chemical or physical change.

Environment

The surroundings or conditions (physical, chemical, mechanical) in which a material exists.

Environmental Cracking

Brittle fracture of a normally ductile material in which the corrosive effect of the environment is a causative factor.

Erosion

The progressive loss of material from a solid surface due to mechanical interaction between that surface and a fluid, a multicomponent fluid, or solid particles carried with the fluid.

Erosion-corrosion

A conjoint action involving corrosion and erosion in the presence of a moving corrosive fluid or a material moving through the fluid, leading to accelerated loss of material.

Etch

A roughened surface produced by chemical, electrochemical or mechanical means. To dissolve unevenly a part of the surface of a material to highlight microstructure in metallography.

Exfoliation Corrosion

Localized subsurface corrosion in zones parallel to the surface that result in thin layers of un-corroded metal resembling the pages of a book.

Fatigue

The phenomenon leading to fracture of a material under repeated or fluctuating stresses having a maximum value less than the tensile strength of the material.

Fatigue Strength

The maximum stress that can be sustained for a specified number of cycles without failure.

Ferralium

Langley Alloys' proprietary super duplex stainless steel (UNS S32550), the first commercially developed super duplex grade, offering high strength and outstanding pitting resistance. *

See: Ferralium 255

Ferrite

The body-centred cubic crystalline phase of iron-based alloys.

Ferrite/phase Balance

The proportion of ferrite to austenite in a duplex microstructure. A near 50:50 balance gives duplex and super duplex steels their combination of strength and corrosion resistance. *

See: Duplex

Ferritic Steel

A steel whose microstructure at room temperature consists predominantly of ferrite.

Filiform Corrosion

Corrosion that occurs under a coating in the form of randomly distributed thread-like filaments.

Fouling

An accumulation of deposits. This includes accumulation and growth of marine organisms on a submerged metal surface and the accumulation of deposits (usually inorganic) on heat exchanger tubing.

Fracture Mechanics

A quantitative analysis for evaluating structural reliability in terms of applied stress, crack length, and specimen geometry.

Free Machining

The machining characteristics of an alloy to which an ingredient has been introduced to give small broken chips, lower power consumption, better surface finish, and longer tool life.

Fretting Corrosion

Deterioration at the interface of two contacting surfaces under load which is accelerated by their relative motion.

Galvanic Anode

A metal that provides sacrificial protection to another metal that is more noble when electrically coupled in an electrolyte. This type of anode is the electron source in one type of cathodic protection.

Galvanic Corrosion

Accelerated corrosion of a metal because of an electrical contact with a more noble metal or non-metallic conductor in a corrosive electrolyte.

Galvanic Couple

A pair of dissimilar conductors, commonly metals, in electrical contact in an electrolyte.

Galvanic Current

The electric current between metals or conductive non-metals in a galvanic couple.

Galvanic Series

A list of metals and alloys arranged according to their corrosion potentials in a given environment.

General Corrosion

Corrosion that is distributed more or less uniformly over the surface of a material.

Grain

An individual crystal in a solid metal or alloy in which the atoms are arranged in an orderly pattern.

Grain Boundary

The irregular junction of two adjacent grains in a metal.

Graphitisation

The formation of graphite in iron or steel, usually from decomposition of iron carbide at elevated temperatures. [Should not be used as a term to describe graphitic corrosion.]

Hardness

Resistance of metal to plastic deformation, usually by indention.

Heat Treatment

Heating and cooling a solid metal or alloy in such a way as to obtain desired properties. Heating for the sole purpose of hot working is not considered heat treatment.

Heat-affected Zone

That portion of the base metal that is not melted during brazing, cutting, or welding, but whose microstructure and properties are altered by the heat of these processes.

Hidurel

Langley Alloys' high-strength copper-nickel alloy (Hidurel 5) designed for bearings and marine/electrical applications. *

See: Hidurel 5

Hiduron

Langley Alloys' family of high-strength copper-nickel alloys (Hiduron 130, Hiduron 191) designed for marine, defence and bearing applications requiring seawater corrosion resistance. *

See: Hiduron 130

High-temperature Hydrogen Attack

A loss of strength and ductility of steel by high-temperature reaction of absorbed hydrogen with carbides in the steel, resulting in decarburization and internal fissuring.

HISC (hydrogen-induced Stress Cracking)

Cracking of high-strength alloys, particularly duplex and super duplex stainless steels, under tensile stress in the presence of hydrogen. A concern for cathodically protected subsea components. *

See: Marine Offshore

Hot Working

Deforming metal plastically at such a temperature and strain rate that recrystallization takes place simultaneously with the deformation, thus avoiding any strain hardening.

Hydrogen Blistering

The formation of subsurface planar cavities, called hydrogen blisters, in a metal resulting from excessive internal hydrogen pressure. Growth of near-surface blisters in low-strength metals usually results in surface bulges.

Hydrogen Embrittlement

A loss of ductility of a metal resulting from absorption of hydrogen.

Hydrogen Stress Cracking

Cracking that results from the presence of hydrogen in a metal in combination with tensile stress. It occurs most frequently with high-strength alloys.

Hydrogen-induced Cracking

Stepwise internal cracks that connect adjacent hydrogen blisters on different planes in the metal, or to the metal surface (also known as stepwise cracking).

Impact Resistance

Ability of a material to resist deformation from impact.

Impingement Corrosion

A form of erosion-corrosion generally associated with the local impingement of a high-velocity, flowing fluid against a solid surface.

Inclusion

A non-metallic phase such as an oxide, sulphide, or silicate particle in a metal.

Incoloy

A trademark of Special Metals Corporation, covering a family of Nickel-Iron-Chrome alloys. The most commonly specified alloys are <a href="https://www.langleyalloys.com/materials/nickel/alloy-825/">INCOLOY 825</a> and <a href="https://www.langleyalloys.com/materials/nickel/alloy-925/">INCOLOY925</a>.

Inconel

A trademark of Special Metals Corporation, covering a family of Nickel-Chromium alloys. The most commonly specified alloys are <a href="https://www.langleyalloys.com/materials/nickel/alloy-718/">INCONEL718</a>, <a href="https://www.langleyalloys.com/materials/nickel/alloy-625/">INCONEL 625</a> and <a href="https://www.langleyalloys.com/materials/nickel/alloy-725/">INCONEL 725</a>.

Interdendritic Corrosion

Corrosive attack of cast metals that progresses preferentially along paths between dendrites.

Intergranular Corrosion

Preferential corrosion at or along the grain boundaries of a metal (also known as intercrystalline corrosion).

Intergranular Stress Corrosion Cracking

Stress corrosion cracking in which the cracking occurs along grain boundaries.

Internal Oxidation

The formation of isolated particles of oxidation products beneath the metal surface.

Ion

An electrically charged atom or group of atoms.

Iron Rot

Deterioration of wood in contact with iron-based alloys.

Knife-line Attack

Intergranular corrosion of an alloy along a line adjoining or in contact with a weld after heating into the sensitization temperature range.

Lining

A coating or layer of sheet material adhered to or in intimate contact with the interior surface of a container used to protect the container against corrosion by its contents and/or to protect the contents of the container from contamination by the container material.

Liquid Metal Cracking

Cracking of a metal caused by contact with a liquid metal.

Low-alloy Steel

Steel with a total alloying element content of less than approximately 5%, but more than specified for carbon steel.

Low-carbon Steel

Steel having less than 0.30% carbon and no intentional alloying additions.

Machinability

The relative ease with which a metal can be cut, judged by tool life, achievable cutting speed and resulting surface finish. *

See: Services/machining

Martensite

A hard supersaturated solid solution of carbon in iron characterized by an acicular (needle-like) microstructure.

Martensitic Steel

Steel in which a microstructure of martensite can be attained by quenching at a cooling rate fast enough to avoid the formation of other microstructures.

Metallising

The coating of a surface with a thin metal layer by spraying, hot dipping, or vacuum deposition.

Microstructure

The structure of a prepared surface of a metal as revealed by a microscope at a magnification exceeding 25x.

Mill Scale

The oxide layer formed during hot fabrication or heat treatment of metals.

Modulus Of Elasticity

A measure of the stiffness or rigidity of a material. It is actually the ratio of stress to strain in the elastic region of a material. If determined by a tension or compression test, it is also called Young’s Modulus or the coefficient of elasticity.

Monel

A trademark of Special Metals Corporation covering a family of Nickel-Copper alloys. The most commonly specified are Monel 400 and <a href="https://www.langleyalloys.com/materials/nickel/alloy-k-500/">Monel K500</a>.

NACE Mr0175 / Iso 15156

The standard qualifying materials for hydrogen sulphide (sour) service in oil and gas environments, with limits on hardness and composition to prevent sulphide stress cracking. *

See: Oil And Gas

Nitriding

Case hardening process in which nitrogen is introduced into the surface of metallic materials (most commonly ferrous alloys). Typical processes include, but are not limited to, liquid nitriding, gas nitriding, and ion or plasma nitriding.)

Nitronic

A trademark owned by Cleveland-Cliffs (formerly AK Steel Corporation, acquired 2020), covering a range of austenitic stainless steels. The most popular product within the family is <a href="https://www.langleyalloys.com/materials/stainless/fermonic-50/">Nitronic 50</a> also commonly referred to as XM-19.

Noble

The positive direction of electrode potential, thus resembling noble metals such as gold and platinum.

Noble Metal

(1) A metal that occurs commonly in nature in the free state. (2) A metal or alloy whose corrosion products are formed with a small negative or a positive free-energy change.

Noble Potential

A potential more cathodic (positive) than the standard hydrogen potential.

Normalising

Heating a ferrous alloy to a suitable temperature above the transformation range (austenitising), holding at temperature for a suitable time, and then cooling in still air to a temperature substantially below the transformation range.

NORSOK

Norwegian petroleum industry standards (e.g. M-650) qualifying manufacturers and materials for offshore service. Langley Alloys' piping projects are supplied to NORSOK-approved materials. *

See: Marine Offshore

Notch Propagation

The increase in depth or length of a cut, nick, or scratch in a material when the material is stressed.

Open-circuit Potential

The potential of an electrode measured with respect to a reference electrode or another electrode in the absence of current.

Oxidation

(1) Loss of electrons by a constituent of a chemical reaction. (2) Corrosion of a metal that is exposed to an oxidising gas at elevated temperatures.

Passivation

A reduction of the anodic reaction rate of an electrode involved in corrosion.

Passive

(1) The positive direction of electrode potential. (2) A state of a metal in which a surface reaction product causes a marked decrease in the corrosion rate relative to that in the absence of the product.

Patina

A thin layer of corrosion product, usually green, that forms on the surface of metals such as copper and copper-based alloys exposed to the atmosphere.

PH

The negative logarithm of the hydrogen ion activity written as: pH = - log10 (aH+), where aH+ = hydrogen ion activity = the molar concentration of hydrogen ions multiplied by the mean ion-activity coefficient.

Pickling

(1) Treating a metal in a chemical bath to remove scale and oxides (e.g., rust) from the surface. (2) Complete removal of rust and mill scale by acid pickling, <a title="Duplex Stainless Steels" href="https://www.langleyalloys.com/materials/duplex/">duplex</a> pickling, or electrolytic pickling.

Pitting

Localized corrosion of a metal surface that is confined to a small area and takes the form of cavities called pits.

Pitting Factor

The ratio of the depth of the deepest pit resulting from corrosion divided by the average penetration as calculated from mass loss.

Plastic Deformation

Permanent deformation caused by stressing beyond the elastic limit.

Plasticity

The ability of a material to deform permanently (non-elastically) without fracturing.

Postweld Heat Treatment

Heating and cooling a weldment in such a way as to obtain desired properties.

Precipitation Hardening

Hardening caused by the precipitation of a constituent from a supersaturated solid solution.

PREN (pitting Resistance Equivalent Number)

A number ranking a stainless steel's resistance to pitting corrosion, calculated as %Cr + 3.3×%Mo + 16×%N. Super duplex grades typically exceed 40. *

See: Super Duplex

Proof Stress (0.2%)

The stress at which a material undergoes 0.2% permanent (plastic) strain. Used as the standard yield measure for alloys with no distinct yield point. See also: Yield Strength. *

Quenching

Rapid cooling in the heat treating of metals, the step of cooling metals rapidly in order to obtain desired properties; most commonly accomplished by immersing the metal in oil or water.

Reduction

Gain of electrons by a constituent of a chemical reaction.

Reference Electrode

An electrode whose open-circuit potential is constant under similar conditions of measurement, which is used for measuring the relative potentials of other electrodes.

Relative Humidity

The ratio, expressed as a percentage, of the amount of water vapour present in a given volume of air at a given temperature to the amount required to saturate the air at that temperature.

Residual Stress

Stress present in a component free of external forces or thermal gradients.

Resistivity

(1) The resistance per unit length of a substance with uniform cross section. (2) A measure of the ability of an electrolyte (e.g., soil) to resist the flow of electric charge (e.g., cathodic protection current). Resistivity data are used to design a ground bed for a cathodic protection system.

Riser

(1) That section of pipeline extending from the ocean floor up to an offshore platform. (2) The vertical tube in a steam generator convection bank that circulates water and steam upward.

Rust

Corrosion product consisting of various iron oxides and hydrated iron oxides. (This term properly applies only to iron and ferrous alloys.)

Rust Bloom

Discoloration indicating the beginning of rusting.

Sacrificial Protection

Reduction of corrosion of a metal in an electrolyte by galvanically coupling it to a more anodic metal (a form of cathodic protection).

Scaling

(1) The formation at high temperatures of thick corrosion-product layers on a metal surface. (2) The deposition of water-insoluble constituents on a metal surface.

Sensitising Heat Treatment

A heat treatment, whether accidental, intentional, or incidental (as during welding), that causes precipitation of constituents (usually carbides) at grain boundaries, often causing the alloy to become susceptible to intergranular corrosion or intergranular stress corrosion cracking.

Shot Peening

Inducing compressive stresses in the surface layer of a material by bombarding it with a selected medium (usually steel shot) under controlled conditions.

Sigma Phase

An extremely brittle Fe-Cr phase that can form at elevated temperatures in Fe-Cr-Ni and Ni-Cr-Fe alloys.

Slip

A deformation process involving shear motion of a specific set of crystallographic planes.

Slow Strain Rate Technique

An experimental technique for evaluating susceptibility to environmental cracking. It involves pulling the specimen to failure in uniaxial tension at a controlled slow strain rate while the specimen is in the test environment and examining the specimen for evidence of environmental cracking.

Solution Heat Treatment

Heating a metal to a suitable temperature and holding at that temperature long enough for one or more constituents to enter into solid solution, then cooling rapidly enough to retain the constituents in solution.

Sour Gas

A gaseous environment containing hydrogen sulphide and carbon dioxide in hydrocarbon reservoirs. Prolonged exposure to sour gas can lead to hydrogen damage, sulphide-stress cracking, and/or stress-corrosion cracking in ferrous alloys.

Spalling

The spontaneous chipping, fragmentation, or separation of a surface or surface coating.

Stainless Steel

Steel containing 10.5% or more chromium, possibly with other elements added to secure special properties.

Standard Electrode Potential

The reversible potential for an electrode process when all products and reactions are at unit activity on a scale in which the potential for the standard hydrogen reference electrode is zero.

Stress Corrosion Cracking

Cracking of a material produced by the combined action of corrosion and tensile stress (residual or applied).

Stress Relieving (thermal)

Heating a metal to a suitable temperature, holding at that temperature long enough to reduce residual stresses, and then cooling slowly enough to minimize the development of new residual stresses.

Sulphidation

The reaction of a metal or alloy with a sulphur-containing species to produce a sulphur compound that forms on or beneath the surface of the metal or alloy.

Sulphide Stress Cracking

Cracking of a metal under the combined action of tensile stress and corrosion in the presence of water and hydrogen sulphide (a form of hydrogen stress cracking).

Super Duplex Stainless Steel

Stainless steel whose microstructure at room temperature consists primarily of a mixture of austenite and ferrite (also called austenitic/ferritic stainless steel), with a chromium content typically >25%.

Tarnish

Surface discoloration of a metal resulting from formation of a film of corrosion product.

Tempering

Heat treatment by heating to a temperature below the lower critical temperature for the purpose of decreasing the hardness and increasing the toughness of hardened steel, hardened cast iron, and sometimes normalized steel.

Tensile Strength

In tensile testing, the ratio of maximum load to original cross-sectional area nb. also called ultimate tensile strength.

Tensile Stress

A stress that causes two parts of an elastic body, on either side of a typical stress plane, to pull apart.

Tension

The force or load that produces elongation.

Thermal Spraying

A group of processes by which finely divided metallic or non-metallic materials are deposited in a molten or semi-molten condition to form a coating.

Ultimate Strength

The maximum stress that a material can sustain.

Uniform Corrosion

Corrosion that proceeds at about the same rate over a metal surface.

UNS (unified Numbering System)

A standardised alphanumeric alloy identification code (e.g. S32760) used across specifications to identify a defined composition. *

Vacuum Degassing

A process by which the amount of carbon in the steel is reduced by exposing liquid steel to a very low vacuum environment. Carbon combines in the process with oxygen to form carbon monoxide, which is removed in the process. The result is a steel that contains lower levels of carbon and thus, has higher formability.

Weld Decay

Intergranular corrosion, usually of stainless steel or certain nickel-base alloys, that occurs as the result of sensitization in the heat-affected zone during the welding operation.

Weld Metal

That portion of a weldment that has been molten during welding.

Werkstoff Number

The European/German material designation (e.g. 2.4858 for Alloy 825) assigned under DIN/EN standards. *

Working Electrode

The test or specimen electrode in an electrochemical cell.

Wrought

Metal in the solid condition that is formed to a desired shape by working (rolling, extruding, forging, etc.), usually at an elevated temperature.

Xm-19

A common highly-alloyed austenitic stainless steel, also known by the tradenames <a href="https://www.langleyalloys.com/materials/stainless/fermonic-50/">Fermonic 50</a> (Langley Alloys) and <a href="https://www.langleyalloys.com/materials/stainless/fermonic-50/">Nitronic 50</a> (Cleveland-Cliffs, formerly AK Steel Corporation)

Yield Point

The stress on a material at which the first significant permanent or plastic deformation occurs without an increase in stress. In some materials, particularly annealed low-carbon steels, there is a well-defined yield point from the straight line defining the modulus of elasticity.

Yield Strength

The stress at which a material exhibits a specified deviation from the proportionality of stress to strain. The deviation is expressed in terms of strain by either the offset method (usually at a strain of 0.2%) or the total-extension-under-load method (usually at a strain of 0.5%).

Zeron 100

Trade name (Rolled Alloys) for super duplex stainless steel UNS S32760, equivalent to Langley Alloys' Alloy 32760. *

See: Alloy 32760