Glossary of Terms

Aluminum:

A reliable deoxidizer because of its great affinity for oxygen. It produces fine austenitic grain size.

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.

Austenitizing:

Forming austenite by heating a ferrous alloy into the transformation range (partial austenitizing) or above the transformation range (complete austenitizing).

Billets:

Usually associated with a solid semi-finished product for further rerolling, reprocessing or reshaping, in dimensions of 2 1/2 in2 minimum to 36 in2.

Blooms:

A semi-finished product rectangular in cross-section, the width not being more than double the thickness and the cross-section usually not less than 36 in2.

Boron:

A non-metallic element added to some steels primarily to improve hardenability and to increase the depth at which the steel will harden when quenched.

Brinell Hardness Test:

a test for determining the hardness of a material by forcing a hard steel or carbide ball of specified diameter into it under a specific load. The result is expressed as the Brinell hardness number, which is the value obtained by dividing the applied load in kilograms by the surface area of the resulting impression in square millimeters.

Capped Steel:

a type of steel with characteristics similar to those of rimmed steels, but to a degree intermediate between those of rimmed and semikilled steels. It can be either mechanically capped or chemical capped when the ingot is cast, but in either case, the full rimming action is stopped, resulting in a more uniform composition than rimmed steel.

Carbon:

the principal hardening element in steel. As carbon content increases, the hardness increases. Tensile strength also increases with the carbon content up to about .85% carbon. Ductility and weldability decrease with increasing carbon.

Carburizing:

Introducing carbon into a solid ferrous alloy by holding above Ac1 in contact with a suitable carbonaceous material. The carburized alloy is usually quench hardened.

Case Hardening:

Hardening a ferrous alloy so that the outer portion, or case, is made substantially harder than the inner portion or core.

Centerless Grinding:

Grinding the surface of a bar mounted on rollers rather than centers.

Charpy Test:

A pendulum-type single blow impact test in which the specimen, usually notched, is supported at both ends as a simple beam and broken by a falling pendulum. The energy absorbed, as determined by the subsequent rise of the pendulum, is a measure of impact strength or notch toughness.

Chromium:

Exerts a toughening effect and increases hardenability, it also improves the surface resistance to abrasion and wear and is used extensively to increase the corrosion resistance of steel.

Cold-Drawing:

The process of pulling a “conditioned” bar (pickled and limed or grit blasted) through a die for the purpose of producing a bright, smooth surface finish and close tolerances.

Core:

In a ferrous alloy, the inner portion that is softer than the outer portion or case.

Elongation:

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

Full Anneal:

Annealing a ferrous alloy by austenitizing and then cooling slowly through the transformation range.

Grain Size:

in killed steels, grain size is specified as either coarse (grain size 1 to 5 inclusive) or fine (grain size 5 to 8 inclusive), determined in accordance with ASTM Designation E112, Standard Methods for Estimating the Average Grain Size of Metals.

Hardenability:

In a ferrous alloy, the property that determines the depth and distribution of hardness induced by quenching.

Hardness:

Resistance of metal to plastic deformation usually by indentation.

Heat Treatment:

Heating and cooling a solid metal or alloy in such a way as to obtain desired conditions or properties. Heating for the sole purpose of hot working is excluded from the meaning of the definition.

Hot-Rolled:

products in the “as-rolled condition” from any hot mill operation.

Impact Test:

A test to determine the behavior of materials when subjected to high rates of loading, usually in bending, tension or torsion. The quantity measured is the energy absorbed in breaking the specimen by a single blow, as in the Charpy or lzod tests.

Ingot:

A mass of metal cast in a form convenient for storage or transportation. The cross section of most ingots approximates a square or rectangle with rounded corners. All ingots are tapered and are commonly cast big-end down. For certain purposes, however, ingots are cast big-end up.

Internal Soundness:

Relative freedom from segregation and porosity, as evaluated by means of a macroetch test which is performed on representative samples.

Isothermal Annealing:

Oustenitizing a ferrous alloy and then cooling to and holding at a temperature at which austenite transforms to a relatively soft ferric carbide aggregate.

Izod Test:

a pendulum-type of single blow impact test in which the specimen, usually notched, is fixed at one end and broken by a falling pendulum. The energy absorbed, as measured by the subsequent rise of the pendulum, is a measure of impact strength or notch toughness.

Killed Steel:

Steel deoxidized with certain deoxidizing elements, such as aluminum, silicon, etc. The term “killed” is used because such additions cause the steel to lie quietly in the molds during solidification.

Lap:

A surface defect appearing as a seam caused by folding over hot metal, fins, or sharp corners and then rolling or forging them into the surface but not welding them.

Manganese:

Contributes to strength and hardness, but to a lesser degree than carbon. The amount of increase in these properties is dependent upon the carbon content, i.e., higher carbon steels are affected more by manganese than lower carbon. Manganese tends to increase the rate of carbon penetration during carburizing.

Maraging:

A precipitation hardening treatment applied to a special group of iron base alloys to precipitate one or more intermetallic compounds in a matrix of essentially carbon-free martensite.

Mill-Shearing:

A defect which can be described as a feathering type light surface lap.

Molybdenum:

Aromotes hardenability in steel and is useful where close hardenability-control is essential. It increases depth-hardness and widens the range of effective heat treating temperatures.

Nickel:

Provides such properties as improved toughness at low temperatures, good resistance to corrosion when used in conjunction with chromium in stainless grades, deep hardening, and ready response to conventional methods of heat treating.

Normalizing:

Heating a ferrous alloy to a suitable temperature above the transformation range and then cooling in air to a temperature substantially below the transformation range.

Phosphorus:

In appreciable amounts increases strength and hardness, but at the sacrifice of ductility and impact toughness, particularly in higher carbon steels that are quenched and tempered. Consequently, for most applications, phosphorus is maintained below a specified maximum.

Quenching:

Rapid cooling.

Recrystallization:

The formation of a new, strain-free grain structure from that existing in cold worked metal, usually accomplished by heating.

Reduction of Area:

The difference, expressed as a percentage of original area, between the original cross-sectional area of a tensile test specimen and the minimum cross-sectional area measured after complete separation.

Rimmed Steel:

A type of steel characterized by a gaseous effervescence when cooling in the mold. This results in a relatively pure iron outer rim.

Rockwell Hardness Test:

A test for determining the hardness of a material based upon the depth of penetration of a specified penetrator into the specimen under certain arbitrarily fixed conditions of test.

Rolled-In Scale:

Rolled-in oxides of iron which form on the surface of hot steel.

Scabs:

Elongated patches of loosened metal which have been rolled into the surface.

Seams:

Open, broken surface running in straight longitudinal lines caused by the presence of oxides near the surface.

Segregation:

A phenomenon associated with solidification, which causes nonuniformity in chemical composition.

Semikil/ed Steel:

Steel that is partially deoxidized so that there is greater degree of gas evolution than in killed steel, but less than in capped or rimmed steel. The uniformity in composition lies between that of killed steel and rimmed steel.

Silicon:

One of the principal deoxidizers used in steelmaking, and, therefore, the amount of silicon present is related to the type of steel. Silicon increases strength and hardness.

Slivers:

Surface ruptures somewhat similar in appearance to skin laminations, but usually more prominent.

Spheroidizing:

Heating and cooling to produce a spheroidal or globular form of carbide in steel.

Strand Casting:

The direct casting of steel from the ladle into slabs, blooms or billets.

Stress Relieving:

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

Sulfur:

Increased sulfur content lowers transverse ductility and notched impact toughness, but has only a slight effect on longitudinal mechanical properties. Weldability decreases with increasing sulfur. Sulfur is added, however, to improve machinability.

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 ratio of maximum load to original cross-sectional area;

also called Ultimate Strength.

Turning:

A method of cold-finishing by machining to size in a lathe or turning machine to remove surface metal formed during hot rolling.

Vanadium:

Used to refine the grain size and enhance the mechanical properties of steel.

Yield Point:

The first stress in a material usually less than the maximum attainable stress, at which an increase in strain occurs without an increase in stress.

Yield Strength:

The stress at which a material exhibits a specified deviation from proportionality of stress and strain.

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