A process in which Quid molecules are taken up by a liquid or solid and distributed throughout the body of that liquid or solid. Compare with adsorption.

Accelerated Cooling
Cooling a plate with water immediately following the final rolling operation. Generally the plate is water cooled from about 1400o F to approximately 1100o F

Accelerated corrosion test
Method designed to approximate, in a short time, the deteriorating effect under normal long-term service conditions.

Accordion Reed Steel
Hardened, tempered, polished and blued or yellow flat steel with dressed edges. Carbon content about 1.00. Material has to possess good flatness, uniform hardness and high elasticity.

Acicular ferrite
A highly sub-structure, non-equiaxed ferrite formed upon continuous cooling by a mixed diffusion and shear mode of transformation that begins at a temperature slightly higher than the transformation temperature range for upper bainite. It is distinguished from bainite in that it has a limited amount of carbon available thus, there is only a small amount of carbide present.

A chemical substance that yields hydrogen ions (H+) when dissolved in water. Compare with base.

Brittleness resulting from pickling steel in acid; hydrogen, formed by the interaction between iron and acid, is partially absorbed by the metal, causing acid brittleness.

Acid embrittlement
A form of hydrogen embrittlement that may be induced in some metals by acid.

A process of making steel, either Bessemer, open-hearth or electric, in which the furnace is lined with a siliceous refractory and for which low phosphorus pig iron is required as this element is not removed.

Acid rain
Atmospheric precipitation with a pH below 3.6 to 5.7. Burning of fossil fuels for heat and power is the major factor in the generation of oxides of nitrogen and sulfur, which are converted into nitric and sulfuric acids washed down in the rain. See also atmospheric corrosion.

Acid Steel
Steel melted in a furnace with an acid bottom and lining and under a slag containing an excess of an acid substance such as silica.

Resin polymerized from acrylic acid, methacrylic acid, eaters of these acids, or acrylonitrile.

The changing of a passive surface of a metal to a chemically active state. Contrast with passivation.

A state in which a metal tends to corrode; referring to the negative direction of electrode potential (opposite of passive or noble).

Active Metal
A metal ready to corrode, or being corroded

Active potential
The potential of a corroding material.

A measure of the chemical potential of a substance, where chemical potential is not equal to concentration, that allows mathematical relations equivalent to those for ideal systems to be used to correlate changes in an experimentally measured quantity with changes in chemical potential.

Activity (ion)
The ion concentration corrected for deviations from ideal behavior. Concentration multiplied by activity coefficient. activity coefficient. A characteristic of a quantity expressing the deviation of a solution from ideal thermodynamic behavior; often used in connection with electrolytes.

Actual throat thickness
The perpendicular distance between two lines each parallel to a line joining the outer toes one being tangent at the weld face and the other being through the furthermost point of fusion penetration.

Addition agent
A substance added to a solution for the purpose of altering or controlling a process. Examples include wetting agents in acid pickles, brighteners or antipitting agents in plating solutions, and inhibitors.

A substance added in a small amount, usually to a fluid, for a special purpose, such as to reduce friction, corrosion, etc.

The surface retention of solid, liquid, or gas molecules, atoms, or ions by a solid or liquid. Compare with absorption.

(1) Exposing to the action of air.
(2) Causing air to bubble through.
(3) Introducing air into a solution by spraying, stirring, or a similar method.
(4) Supplying or infusing with air, as in sand or soil.

Aeration Cell
An oxygen concentration cell; an electrolytic cell resulting from differences in dissolved oxygen at two points. Also see differential aeration cell..

Age Hardening
The term as applied to soft or low carbon steels, relates to slow, gradual changes that take place in properties of steels after the final treatment. These changes, which bring about a condition of increased hardness, elastic limit, and tensile strength with a consequent loss in ductility, occur during the period in which the steel is at normal temperatures.

Agglomerating Processes

Fine particles of limestone (flux) and iron ore are difficult to handle and transport because of dusting and decomposition, so the powdery material usually is 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 Iron Briquetting (HBI) is a concentrated iron ore substitute for scrap for use in electric furnaces.

Spontaneous change in the physical properties of some metals, which occurs on standing, at atmospheric temperatures after final cold working or after a final heat treatment. Frequently synonymous with the term “ Age-Hardening.”

Air-arc cutting
Thermal cutting using an arc for melting the metal and a stream of air to remove the molten metal to enable a cut to be made.

Air Cooling
Cooling of the heated metal, intermediate in rapidity between slow furnace cooling and quenching, in which the metal is permitted to stand in the open air.

Air-Hardening Steel
A steel containing sufficient carbon and other alloying elements to harden fully during cooling in air or other gaseous mediums from a temperature above its transformation range. Such steels attain their martensitic structure without going through the quenching process. Additions of chromium, nickel, molybdenum and manganese are effective toward this end. The term should be restricted to steels that are capable of being hardened by cooling in air in fairly large sections, about 2 in. or more in diameter.

AISI (American Iron and Steel Institute)
An association of North American companies that mine iron ore and produce steel products. There are 50 member companies and more than 100 associate members, which include customers that distribute, process, or consume steel. The AISI has reorganized into a North American steel trade association, representing the interests of Canada, Mexico, and the United States. Common and alloy steels have been numbered in a system essentially the same as the SAE. The AISI system is more elaborate than the SAE in that all numbers are preceded by letters: A represents basic open-hearth alloy steel, B acid Bessemer carbon steel, C basic open-hearth carbon steel, CB either acid Bessemer Or basic open-hearth carbon steel, E electric furnace alloy steel.

Composite sheet produced by bonding either corrosion-resistant aluminum alloy or aluminium of high purity to base metal of structurally stronger aluminium alloy. The coatings are anodic to the core so they protect exposed areas of the core electrolytically during exposure to corrosive environment.

Alkali metal
A metal in group lA of the periodic system - namely, lithium, sodium, potassium, rubidium, cesium, and francium. They form strongly alkaline hydroxides, hence the name.

(1) Having properties of an alkali.
(2) Having a pH greater than 7.

Alkaline cleaner
A material blended from alkali hydroxides and such alkaline salts as borates, carbonates, phosphates, or silicates. The cleaning action may be enhanced by the addition of surface-active agents and special solvents.

Resin used in coatings. Reaction products of polyhydric alcohols and polybasic acids

(1) A chemical process in which an alkyl radical is introduced into an organic compound by substitution or addition.
(2) A refinery process for chemically combining isoparaffin with olefin hydrocarbons.

(1) Pronounced wide cracking over the entire surface of a coating having the appearance of alligator hide.
(2) The longitudinal splitting of flat slabs in a plane parallel to the rolled surface. Also called fish-mouthing.

(See Polymorphism)

Metal prepared by adding other metals or non-metals to a basic metal to secure desirable properties.

Alloying Element
Any metallic element added during the making of steel 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.

Alloy plating
The codeposition of two or more metallic elements.

Alloy Steel
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. Addition of such alloying elements is usually for the purpose of increased hardness, strength or chemical resistance.

Alloy Surcharge
The addition to the producer's selling price included in order to offset raw material cost increases caused by higher alloy prices.

Alpha Brass
A copper-zinc alloy containing up to 38% of zinc. Used mainly for cold working.

Alpha Bronze
A copper-tin alloy consisting of the alpha solid solution of tin in copper. Commercial forms contain 4 or 5% of tin. This alloy is used in coinage, springs, turbine, blades, etc.

Alpha Iron
The polymorphic form of iron, stable below 1670 (degrees) F. has a body centered cubic lattice, and is magnetic up to 1410 (degrees) F.

Alternate-immersion test
A corrosion test in which the specimens are intermittently exposed to a liquid medium at definite time intervals.

A gas welding technique in which the flame rightward welding

Forming of an aluminum or aluminum alloy coating on a metal by hot dipping, hot spraying, or diffusion

Aluminum (Al)
Chemical symbol Al, Element No. 13 of the periodic system; Atomic weight 26.97; silvery white metal of valence 3; melting point 1220 (degrees) F; boiling point approximately 4118 (degrees) F.; ductile and malleable; stable against normal atmospheric corrosion, but attacked by both acids and alkalis. Aluminium is used extensively in articles requiring lightness, corrosion resistance, electrical conductivity, etc. Its principal functions as an alloy in steel making;
(1) Deoxidises efficiently.
(2) Restricts grain growth (by forming dispersed oxides or nitrides)
(3) Alloying element in nitriding steel.

Aluminum Killed Steel
A steel where aluminum has been used as a deoxidizing agent.

All-weld test piece
A block of metal consisting of one or more beads or runs fused together for test purposes. It may or may not include portions of parent metal.

All-weld test specimen
A test specimen that is composed wholly of weld metal over the portion to be tested.

An alloy of mercury with one or more other metals

An instrument for measuring the magnitude of electric current flow.

Amorphous solid
A rigid material whose structure lacks crystalline periodicity; that is, the pattern of its constituent atoms or molecules does not repeat periodically in three dimensions. See also metallic glass..


A term applied to oxides and hydroxides which can act basic toward strong acids and acidic toward strong alkalis. Substances which can dissociate electrolytically to produce hydrogen or hydroxyl ions according to conditions.

In the absence of air or unreacted or free oxygen.

A zinc-iron phosphate coating for iron and steel.

An ion or radical which is attracted to the anode because of the negative charge. See also cation and ion

Heating to and holding at a suitable temperature and then cooling at a suitable rate, for such purposes as reducing hardness, improving machinability, facilitating cold working, producing a desired microstructure, or obtaining desired mechanical, physical, or other properties. When applicable, the following more specific terms should be used: black annealing, blue annealing, box annealing, bright annealing, flame annealing, graphitizing, intermediate annealing, isothermal annealing, malleablizing, process annealing, quench annealing, re-crystallization annealing, and spherodizing. When applied to ferrous alloys, the term annealing, without qualification, implies full annealing. When applied to nonferrous alloys, the term annealing implies a heat treatment designed to soften an age-hardened alloy by causing a nearly complete precipitation of the second phase in relatively coarse form. Any process of annealing will usually reduce stresses, but if the treatment is applied for the sole purpose of such relief, it should be designated stress relieving.

  • WHAT
    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.
  • WHY
    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 high temperature.
  • HOW
    There are two ways to anneal cold-rolled steel coils: batch and continuous.

(1) BATCH (BOX). Three to four coils are stacked on top of each other, and a cover is placed on top. For up to three days, the steel is heated in a non-oxygen atmosphere (so it will not 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.

The electrode at which oxidation or corrosion of some component occurs (opposite of cathode). Electrons flow away from the anode in the external circuit.

Anode corrosion
The dissolution of a metal acting as an anode.

Anode corrosion efficiency
Ratio of actual to theoretical corrosion based on the total current flow calculated by Faraday's law from the quantity of electricity that has passed.

Anode effect
The effect produced by polarization of the anode in electrolysis. It is characterized by a sudden increase in voltage and a corresponding decrease in amperage due to the anode becoming virtually separated from the electrolyte by a gas film.

Anode efficiency
Current efficiency of the anode.

Anode film

  • (1) The portion of solution in immediate contact with the anode, especially if the concentration gradient is steep.
  • (2) The outer layer of the anode itself.

Anodic cleaning
Electrolytic cleaning in which the work is the anode. Also called reverse-current cleaning.

Anodic coating
A film on a metal surface resulting from an electrolytic treatment at the anode.

Anodic inhibitor
A chemical substance or combination of substances that prevent or reduce the rate of the anodic or oxidation reaction by a physical, physico-chemical or chemical action

Anodic polarization
The change in the initial anode potential resulting from current flow effects at or near the anode surface. Potential becomes mode noble (more positive) because of anodic polarization.

Anodic potential
An appreciable reduction in corrosion by making a metal an anode and maintaining this highly polarized condition with very little current flow.

Anodic protection
A technique to reduce corrosion of a metal surface under some conditions by passing sufficient to it to cause its electrode potential to enter and remain in the passive region; imposing an external electrical potential to protect a metal from corrosive attack. (Applicable only to metals that show active-passive behavior.) Contrast with cathodic protection.

Anodic reaction
Electrode reaction equivalent to a transfer of positive charge from the electronic to the ionic conductor. An anodic reaction is an oxidation process. An example common in corrosion is: Me ~ Me n+ + ne .

Anodizing (Aluminum Anodic Oxide Coating)
A process of coating aluminum by anodic treatment resulting in a thin film of aluminum oxide of extreme hardness. A wide variety of dye colored coatings are possible by impregnation in process.

The electrolyte adjacent to the anode in an electrolytic cell.

Intended to prevent fouling of under-water structures, such as the bottoms of ships; refers to the prevention of marine organism's attachment or growth on a submerged metal surface, generally through chemical toxicity caused by the composition of the metal or coating layer.

Antipitting agent
An addition agent for electroplating solutions to prevent the formation of pits or large pores in the electrodeposit.

Pertaining to water; an aqueous solution is made by using water as a solvent.

Arc blow
A lengthening or deflection of a DC welding arc caused by the interaction of magnetic fields set up in the work and arc or cables.

Arc fan
The fan-shaped flame associated with the atomic-hydrogen arc.

Arc voltage
The voltage between electrodes or between an electrode and the work, measured at a point as near as practical to the work.

Arc Welding
A group of welding processes wherein the metal or metals being joined are coalesced by heating with an arc, with or without the application of pressure and with or without the use of filler metal.

Argon-Oxygen Decarburization (AOD)

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

  • WHY
    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. Additionally, using AOD for refining stainless steel increases the availability of the EAF for melting purposes.

  • HOW
    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.

Artificial Aging
An aging treatment above room temperature. (See Precipitation Heat Treatment and compare with natural aging).

Abbreviation for American Society For Testing Material. An organization for issuing standard specifications on materials, including metals and alloys.

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

Atomic-hydrogen welding
Arc welding in which molecular hydrogen, passing through an arc between two tungsten or other suitable electrodes, is changed to its atomic form and then re-combines to supply the heat for welding

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

  • WHY
    Most unionized companies cannot unilaterally reduce their employment levels to cut costs, so management must rely on attrition to provide openings that they, in turn, do 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.

Quenching a ferrous alloy from a temperature above the transformation range, in a medium having a rate of heat abstraction high enough to prevent the formation of high-temperature transformation products, and then holding the alloy, until transformation is complete, at a temperature below that of pearlite formation and above that of martensite formation.

Phase in certain steels, characterized as a solid solution, usually off carbon or iron carbide, in the gamma form of iron. Such steels are known as “austenitic”. Austenite is stable only above 1333°F. in a plain carbon steel, but the presence of certain alloying elements, such as nickel and manganese, stabilizes the austenitic form, even at normal temperatures. 

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).

Austenitic Steel
Steel which, because of the presence of alloying elements, such as manganese, nickel, chromium, etc., shows stability of Austenite at normal temperatures. 

Forming austenite by heating a ferrous alloy into the transformation range (partial austenitizing) or above the transformation range (complete austenitizing). When used without qualification, the term implies complete austenitizing.

Auto Stamping Plant
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.

Automatic Gauge Control
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.

A radiograph recorded photographically by radiation spontaneously emitted by radioisotopes that are produced in, or added to, the material. This technique identifies the locations of the radioisotopes.

Auxiliary anode
In electroplating, a supplementary anode positioned so as to raise the current density on a certain area of the cathode and thus obtain better distribution of plating.

Auxiliary electrode
An electrode commonly used in polarization studies to pass current to or from a test electrode, usually made of non- corroding material.