Glossary of Terms
Click on any term to see its definition.
Changes in physical and mechanical properties that occur when low carbon steel is stored for some time. Aging is also accelerated by exposure of steel to elevated temperatures. Stretcher strains and fluting can result from aging.
Generally refers to the heating and controlled cooling of solid material for the purpose of removing stresses, making it softer, refining its structure or changing its ductility, toughness or other properties.
• AS ROLLED
Bars that are hot rolled and allowed to cool in the air, they are said to be “as rolled” or in the natural condition.
Deviation from edge straightness, usually referring to the greatest deviation of side edge from a straight line, the measurement being taken on the concave side with a straight edge. In sheet and strip the greatest deviation of a side from a straight line. In structurals: the curvature from the plane of a flange in the length of the section, either leg of an angle being taken as the flange.
• CARBON STEEL
Steel which owes its properties chiefly to carbon without substantial amounts of other alloying elements; also known as straight carbon steel or plain carbon steel. Steel is classified as carbon steel when the maximum content does not exceed the following percentages: Manganese: 1.65; Silicon: 0.06; Copper 0.60 (when specified).
• 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.
• COIL BREAK
Creases or ridges which appear as parallel lines, transverse to the direction of rolling. They generally extend across the width of the sheet.
• COLD FINISHING
Changing the shape of, or reducing the cross-section of steel while cool. Usually accomplished by rolling or drawing through a die or turning.
• COLD ROLL PRODUCTS
Flat rolled products for which the approximate required thickness has been obtained by rolling without heating at approximately room temperature.
• COMMERCIAL STEEL
Sheet of this quality (also known as Commercial Quality) is for uses involving simple bending or moderate drawing. Commercial quality sheet can be bent flat upon itself in any direction at room temperature.
Gradual chemical or electrochemical attack on a metal by atmospheric moisture or other agents.
• DRAWING QUALITY
As compared with commercial quality sheet, drawing quality sheet has a greater degree of ductility and is more consistent in performance. The greater ductility and uniformity result from higher standards of production, selection, and processing of the steel.
• DRAWING QUALITY SPECIAL KILLED
When drawing quality will not provide a sufficient degree of ductility for the fabrication of parts, or applications require that the sheet be free from aging, drawing quality special killed should be used. The quality is made by special steelmaking and processing practices. Also sometimes known as deep drawing quality.
The ability of a material to deform physically without fracturing, being measured by elongation or reduction of area in a tensile test, by height of cupping in an Erichsen test, or by other means.
• EDGE CONDITION
A mill edge is the normal edge produced in rolling, and does not conform to any definite contour. A sheared edge is one that has been cut after rolling. A slit edge results when a strip is cut into multiple widths by means of a rotary knife.
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.
• FLOOR PLATE
Plates rolled with special projections or buttons on one surface to provide a non-slip grip.
A series of sharp parallel kinks or creases occurring in the arc when sheet steel is formed cylindrically, stretching the outer surface well beyond its yield point.
The process of applying a coating of zinc to the finished cold-reduced sheet or to fabricated parts made of strip products. The coating is applied by hot dipping or electrolytic deposition.
The term grade designates divisions within different types based on carbon content or mechanical properties; for example, “This is a high tensile (grade) structural steel.”
A method of conditioning steel which makes use of a power-driven grinding wheel.
Quenching steel, or cooling it rapidly from a temperature above the transformation temperature. Steel is quenched in water or brine for rapid cooling, in oil for some alloy steels, and in air for certain alloy steels. After steel is quenched it is usually very hard and brittle and must be tempered.
Heating and cooling a solid metal or alloy in such a way as to obtain desired conditions and properties. Heating for the sole purpose of hot working is excluded from the meaning of this definition.
• HIGH STRENGTH STEEL
Low alloy steels forming a specific class in which enhanced mechanical properties and, in most cases, good resistance to atmospheric corrosion are obtained by the incorporation of moderate proportions of one or more alloying elements other than carbon. The preferred terminology is now “high-strength, low-alloy steels.”
• HOT ROLLED
This term describes flat steel products that are brought to approximate finished size by rolling at high temperatures.
Particles of foreign material in a metallic matrix. The particles are usually compounds (such as oxides, sulfides, or silicates), but may be of any substance that is foreign to (and essentially insoluble in) the matrix.
• KILLED STEEL
Steel deoxidized by silicon or aluminum to reduce the oxygen content to a minimum so that no reaction occurs during solidification of the metal. Killed steels have more uniform properties and chemical composition than other steels.
Imperfections (separations or weakness) resulting from the presence of blisters, seams or foreign inclusions aligned parallel to the worked surface of a metal.
A surface imperfection, 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.
The flattening of steel plates and sheets. There are several methods, such as roller leveling and stretcher leveling.
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The ease of metal removal during machining, the tool life obtained, the surface finish obtained or any combination of the three.
In general, the cutting away of the surface of a metal by means of power-driven machinery. Specifically, a method of conditioning steel by machining away the surface.
• MECHANICAL PROPERTIES
The properties of a material that reveal its elastic and inelastic behavior when force is applied, thereby indicating its suitability for mechanical applications; for example, modulus of elasticity, tensile strength, elongation, hardness, and fatigue limit.
The science which deals with the extraction of metals form their ores and the adaptation and application of these metals to the uses for which they are intended.
• MILL EDGE
Normal rounded edge produced in Hot Rolling of flat steel. Does not conform to any standard radius. Replaces the old term, band edge.
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. Steel is normalized to refine grain size, make it structure more uniform or to improve machinability.
Application of a suitable oil to final product to retard rusting. Where surface is a consideration, it is also desirable in reducing friction scratches that may develop in transit. The oil coating is not intended to serve as a lubricant for subsequent fabrication.
• PHYSICAL PROPERTIES
Properties of a metal or alloy that are relatively insensitive to structure and can be measured without the application of force; for example, density, electrical conductivity, coefficient of thermal expansion, magnetic permeability and lattice parameter. Does not include chemical reactivity.
Removal of mill scale or oxide by immersion of steel in a dilute solution of sulphuric or hydrochloric acid. The steel is then rinsed and dried.
• 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.
A method of shearing to meet closer-than-standard width, length, and out-of-square tolerances.
Complex forms of oxides of iron which form on the surface of hot steel.
• SCREW STOCK
Metal in the form of wire or rod, ordinarily a free-machining type of alloy used for making screw-machine products.
On the surface of a metal, an unwelded fold or lap that appears as a crack, usually resulting from a discontinuity obtained in casting or in mechanical working.
An imperfection consisting of a very thin elongated piece of metal attached by only one end to the parent metal into whose surface it has been worked.
The spangle of a galvanized sheet surface is the visual manifestation of zinc when it solidifies as the sheet emerges from the pot of molten zinc in a galvanize line. Similar appearances are developed when moisture freezes on a window. The zinc crystal or spangle varies in size, brightness, and appearance depending upon a number of factors, most of which are related to cooling rate.
• STRESS RELIEVING
The heating of steel to a temperature below the transformation temperature, as in tempering, but is done primarily to relieve internal residual stresses and then cooling slowly enough to minimize the development of new residual stresses.
• STRETCHER LEVELING
Stretches material beyond its yield point to equalize the stresses, providing a product with superior flatness. This activity produces material that stays flat.
• STRUCTURAL QUALITY
When mechanical property values other than bend tests, such as tensile or yield point elongation, Rockwell hardness, or similar tests are specified or required.
In reference to wide flange beams, sweep is the curvature from the plane of the web in the length of the beam.
A condition produced in a metal or alloy by mechanical or thermal treatment and having characteristic structure and mechanical properties. A given alloy may be in the fully softened and annealed temper, or it may be cold worked to the hard temper, or further to spring temper. Intermediate tempers produced by cold working (rolling or drawing) are called “quarter-hard,” “half-hard” and “three-quarter hard,” and are determined by the amount of cold reduction and the resulting tensile properties. In addition to the annealed temper, conditions produced by thermal treatment are the solution heat treated temper and the heat-treated and artificially aged temper. Other tempers involve a combination of mechanical and thermal treatments and include temper produced by cold working after heat treating, and temper produced by artificial aging of alloys that are as-cast, as-extruded, as-forged, heat treated and worked.
• TEMPER ROLLING (PASSING)
A relatively light cold rolling operation that may be used on hot rolled, cold rolled and some coated sheet such as galvanized. Temper rolling hot rolled sheet helps to improve flatness, minimize coil breaks and fluting and alter mechanical properties. Temper rolling cold reduced and coated sheet steel improves surface finish, alters mechanical properties and reduces the tendency of the steel to flute during fabrication.
Consists of reheating quenched steel to a suitable temperature below the transformation temperature for an appropriate time and cooling back to room temperature. This decreases the hardness and increases the toughness of the steel.
• TENSILE STRENGTH
In tensile testing, the ration or maximum load to the original cross-sectional area. Also called ultimate strength.
• THEORETICAL NOMINAL WEIGHT
Most steel weights are nominal and based on a theoretical derived weight. There are apt to be differences between nominal weights and actual scale weights due to manufacturing practices.
• TOLERANCE LIMIT
The permissible deviation from the desired value.
A method of removing the surface from a circular piece by bringing the cutting edge of a tool against it while the piece is rotated.
• 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. Only certain materials exhibit a yield point.
• YIELD STRENGTH
The stress at which a material exhibits a specified deviation from the proportionality of stress and strain. An offset of 0.2% is used for many metals.