Knowing the correct terminology for the Steel Industry is important for many people.  If you have terms that you feel we should add please contact us at service@cardmet.com we will be glad for your input.

           

A

ACID EMBRITTLEMENT

A form of hydrogen embrittlement which may be induced in some metals by acid treatment such as pickling.

AGING

In a metal or alloy, a change in properties that generally occurs slowly at room temperature and more rapidly at higher temperatures.

ALLOYING ELEMENTS

An element added to a metal to effect changes in property, and which remains within the metal.

ANNEALING

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.  Annealing is a broad term covering such thermal treatments as full annealing, normalizing, etc.  When applying to ferrous alloys, the term “annealing,” without qualification, implies full annealing.

B

BANDED STRUCTURE

A segregated structure of nearly parallel bands aligned in the direction of working.

BARK

The decarbonized layer just beneath the scale that results from heating steel in an oxidizing atmosphere.

BESSEMER PROCESS

A process for making steel by blowing air through molten pig iron containing in a refractory lined vessel so as to remove by oxidation most of the carbon, silicon and manganese.

BILLET

A solid semi-finished round or square product that has a minimum width or thickness of 1- ½ inches and the cross-sectional area varies from 2-¼ to 36 square inches.

BLACK ANNEALING

Box annealing or pot annealing ferrous alloy sheet, strip or wire.  See box annealing.

BLAST FURNACE

A vertical shaft type furnace used for reducing iron ore to pig iron in a continuous operation.  The furnace is charged from the top, the air blast entering the bottom.

BLISTER

A defect produced by gas bubbles.

BLOWHOLE

A hole in a casting or a weld caused by gas entrapped during solidification.

BLUE ANNEALING

Heating hot rolled ferrous sheet in an open furnace to a temperature within the transformation range and then cooling in air, in order to soften the metal.  The formation of a bluish oxide on the surface.

BLUE BRITTLENESS

Brittleness occurring in some steels after being heated within the range of 300 to 650° Fahrenheit and more especially if the steel is worked at the elevated temperature.  Killed steels are virtually free of this kind of brittleness.

BOX ANNEALING

Annealing steel by heating in a sealed container under conditions that minimize oxidation.

BRIGHT ANNEALING

Annealing in a protective medium to prevent discoloration of the surface.

C

CARBON STEEL

Steel is classed as carbon steel when no minimum content is specified or required for aluminum, boron, chromium, cobalt, columbium, molybdenum, nickel, titanium, tungsten, vanadium or zirconium, or any other element added to obtain a desired ally effect; when the specified minimum for copper does not exceed 0.40%; or when the maximum content specified for maganese does not exceed 1.65%; silicon .60%; copper .60%.

CARBURIZING

Introducing carbon into a solid ferrous ally by holding above the critical temperature in contact with a suitable carbonaceous material, which may be a solid, liquid or gas.

CASE

In a ferrous alloy, the outer portion that has been made harder than the inner portion, or core, by carburizing and hardening.

CHIPPING

Removing seams and other surface defects in metals manually with chisel or gouge or by a continuous machine, before further processing.

CLEAVAGE PLANE

Planes along which crystals fracture more easily.

COLD SHUT

A place in metal where two portions of the metal in either a molten or plastic condition have failed to unite into a solid mass.

COLD WORKING

Plastic deformation of a metal at a temperature low enough to insure strain hardening.

CORE

The center portion of a piece of steel which may be of different chemical composition than the outside, as in the case of carburized parts, or which may have different mechanical properties than the outside due to the failure of penetration of heat treatment effect.

CROP

The defective ends of a rolled or forged product which are cut off and discarded.

CYANIDING

Introducing carbon and nitrogen into a solid ferrous ally by holding above the critical temperature in contact with molten cyanide salt of suitable composition.

D

DECARBURIZATION

The loss of carbon from the surface of a ferrous alloy as a result of heating in a medium that reacts with the carbon at the surface.

DRAWING BACK

A misnomer for tempering.  See tempering.

E

ELASTIC LIMIT

Strictly speaking the elastic limit of a material is the producing a measurable change in length after the load is released.  Owing to the difficulty of making a test to determine the true elastic limit, it is common practice to apply the load at a constant rate of increase and also measure the increase of length of the specimen at uniform load increments.  The point, at which the increase in length of the specimen ceases to bear a direct ratio to the increase in load, is called the proportional limit.  For commercial purposes the elastic limit and the proportional limit may be considered equal, although the elastic limit will usually be slightly higher than the proportional limit.

ELONGATION

In tensile testing, the increase in the gage length, measured after fracture of the specimen within the gage length, usually expressed as a percentage of the original gage length.

ENDURANCE LIMIT

Maximum stress to which material may be submitted without causing fatigue failure.

EUTECTOID STEEL

A steel consisting of nothing but pearlite (about .90 carbon)

F

 

FERROALLOY

An alloy of iron that contains a sufficient amount of one or more other chemical elements to be useful as an agent for inducing these elements into a molten metal, usually steel.

FIBER

A fibrous or woody appearing structure found in fractures of wrought metal, and generally indicating directional properties.

FINISHING TEMPERATURE

Temperature at which the hot working is finished.

FRACTURE TEST

Breaking a metal specimen and examining the fractured surface with the unaided eye or a low-power microscope to determine such things as composition, grain size, case depth, soundness or presence of defects.

FULL ANNEALING

Heating to above the critical temperature range followed by slow cooling through the range.

G

GRAINS

Metal crystals.

GRAIN GROWTH (coarsening)

An increase in the size of grains in polycrystalline metal, usually effected during heating at elevated temperatures.

H

HARDENING

Increasing the hardness by suitable treatment, usually involving heating and cooling.  When applicable, the following flame hardening, induction hardening, precipitation hardening and quench hardening.

HEAT TREATMENT

Method of heating and cooling of finished metals or alloys to produce certain desirable properties and conditions.

HOT SHORTNESS

Brittleness in metal in the hot forming range.

HOT WORKING

Deforming metal plastically at such a temperature and rate that strain hardening does not occur.

HYPEREUTECTOID STEEL

A steel having more than the eutectoid percentage (about .90) of carbon.

HYPO—EUTECTOID STEEL

A steel having less than the eutectoid percentage (about .90) of carbon.

MPACT TEST

A test to determine the behavior of materials when subjected to high rates of loading, usually in bending, tension or torsion.

I

INGOT

A casting suitable for working or remelting.

INGOT IRON

Commercially pure open-hearth iron.

J

K

KILLED STEEL

Steel deoxidized with a strong deoxidizing agent such as silicon or aluminum in order to reduce the oxygen content to such a level that no reaction occurs between carbon and oxygen during solidification.

L

LAP

A seamlike surface defect caused by folding over fins or sharp corners in hot metal and then rolling or forging them into the surface.

LAP WELD

Weld made on overlapped edges of scarfed or beveled skelp to form tubing or pipe.

M

MACROSTRUCTURE

The structure of metals as revealed by examination of the etched surface of a polished specimen at a magnification not exceeding ten diameters.

MECHANICAL WORKING

Working metal through rolls, presses, hammers, etc., to change its shape, properties or structure.

MODULUS OF ELASTICITY

A measure of the rigidity of metal.  Ratio of stress, within proportional limit, to corresponding strain.  Specifically, the modulus obtained in tension or compression is Young’s modulus, stretch modulus or modulus of extensibility; the modulus obtained in torsion; the modulus covering the ratio of the mean normal stress to the change in volume is the bulk modulus.  The tangent modulus and secant modulus are not restricted within the proportional limit; the former is the slope of the stress-strain curve at a specified point; the latter is the slope of a line from the origin to a specified point on the stress- strain curve.  Also called “elastic modulus” and “coefficient of elasticity.”

N

NETWORK STRUCTURE

A structure in which the crystals of on constituent are surrounded by envelopes of another constituent which gives a network appearance to an etched test specimen.

NITRIDING

Adding nitrogen by heating at a temperature below the critical in contact with some nitrogenous material.

NORMALIZING

Heating to about 100°F. above the critical temperature and cooling in still air to ordinary temperature.

O

OVERHEATING—Heating a metal or alloy to such a high temperature that its properties are impaired.  When the original properties cannot be restores by further heat treating, by mechanical working or by a combination of working and heat treating, the overheating is know then as burning.

P

PIG IRON—High carbon iron—made by reduction of iron ore in the blast furnace.

PIPE—The central cavity formed by contraction in metal, especially in ingots, during solidification.

PROPORTIONAL LIMIT—The maximum stress at which strain remains directly proportional to stress.

Q

QUENCHING—Cooling rapidly from the hardening temperature by subjecting the part to the proper coolant such as oil, water, molten salt, molten lead, airblast, etc.

R

 

RED SHORTNESS—Brittleness in metal in the hot forming range.

REDUCTION OF AREA—The decreased of cross-sectional area of a tension test-specimen at a point of rupture, expressed as percentage of original area.

REFINING TEMPERATURE—Temperature at which the grain size and structure of the steel is refined, usually above the upper critical.

RIMMED STEEL—A low-carbon steel containing sufficient iron oxide to give a continuous evolution of carbon monoxide while the ingot is solidifying, resulting in a case or rim of metal virtually free of voids.  Sheet and strip products made from the ingot have very good surface quality.

S

SEAM—On the surface of metal, an unwelded fold or lap, which appears as a crack, usually resulting from a defect obtained in casting or working.

SELF-HARDENING STEEL (Air Hardening)—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.  The term should be restricted to steels that are capable of being hardened by cooling in air in fairly large sections about two inches or more in diameter.

SHORTNESS—Brittleness.

SINKHEAD OR HOT TOP—An insulated reservoir on top of an ingot mold holding excess molten metal which it feeds to the ingot proper when shrinkage occurs.  Designed to prevent pipe.

SKELP—Steel or iron plate from which pipe or tubing is made.

SLAB—A piece of metal, intermediate between ingot and plate, with the width at least twice the thickness for rolling down into plates.

SLABBING MILL—A primary mill which produces slabs.

SOAKING—Holding steel at fixed temperature long enough for a complete, uniform penetration of the heat.

SONIMS—Composite word derived for Solid Non-metallic IMpuritieS.

SPALLING—Cracking and flaking of the metal surface.

SPHEROIDIZING—Prolonged heating at a temperature near the critical range followed by relatively slow cooling, causing the carbides to assume approximately a spherical shape.
T

TAPPING—Opening the outlet of a melting furnace to move metal.

TEEMING—Pouring a molten metal from a ladle into ingot molds, particularly iron or steel.

TEMPERING—Reheating a quench-hardened or normalized ferrous alloy to a temperature below the transformation range and then cooling at any desired rate.

TENSILE STRENGTH—The maximum load per unit of original cross-sectional area obtained before rupture.

U

V

W

WORK HARDNESS—Hardness resulting from mechanical working.

x

Y

YIELD POINT—The load per unit of original cross-section area at which a marked increase in the deformation of the specimen occurs without increase of load.  It is usually calculated from the load determined by the drop of the beam of the testing machine or by use of dividers.

Z