Glossary of Metal Terms



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.


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.”


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.


Alloy steel which may be hardened by cooling in air from a temperature above the 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.


Steels of the American Iron and Steel Institute. 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.


The common name for a type of clad wrought aluminum products, such as sheet and wire, with coatings of high-purity aluminum or an aluminum alloy different from the core alloy in composition. The coatings are anodic to the core so they protect exposed areas on the core electrolytically during exposure to corrosive environments.


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


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, vanadium, or tungsten are present. An enormous variety of distinct properties can be created for the steel by substituting these elements in the recipe to increase hardness, strength, or chemical resistance. (See STEEL)


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


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.


The polymorphic form of iron, stable below 1670°F. has a body centered cubic lattice, and is magnetic up to 1410° F.


Chemical symbol Al. Silvery white metal; ductile with tensile strength and malleable; resistant to corrosion, but can be attacked by acids and alkalis; good conductor of electricity. Lightweight, strong metal produced from alumina, which is processed from bauxite ore. Commercial use is only 100 years old, yet the metal is second only to steel in tonnage consumed annually. Used extensively in articles requiring lightness, corrosion resistance, or electrical conductivity. Metal is used to make transportation, packaging, building, electrical, and consumer durable products.


A steel where aluminum has been used as a deoxidizing agent. (See Killed Steel.)


A heat or thermal treatment process by which a previously cold-rolled coil of metal is made more suitable for forming and bending. The sheet is heated to a designated temperature for a sufficient amount of time and then cooled either in batches or in a continuous annealing process.


Aluminum coated with a thin film of oxide (applied by anodic treatment) resulting in a surface with extreme hardness. A wide variety of dye-colored coatings are made possible by impregnation in the anodizing process.


Chemical symbol Sb. Silvery white and lustrous, it exhibits poor heat and electrical conductivity. It is used primarily in compounds such as antimony trioxide for flame-retardants. Other applications include storage battery components (lead-antimony), ceramics, glass, friction bearings, ammunition, cable sheaths and tank linings. It also is used as an alloying agent in metal castings.


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.


A trade name for a patented heat treating process that consists of quenching a ferrous alloy from temperature above the transformation ranges, in a medium having a rate of heat abstraction sufficiently high to prevent the formation of high-temperature transformation products and in maintaining the alloy, until transformation is complete, at a temperature below that of pearlite formations 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.


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


A cold-rolled, low-carbon sheet steel used for automotive body panel applications. Because of the steel's special processing, it has good stamping and strength characteristics, and, after paint is baked on, improved dent resistance.


Surface of metal, under the oxide-scale layer, resulting from heating in an oxidizing environment. In the case of steel, such bark always suffers from decarburization.


A relatively long, straight, rigid piece of metal; long steel products rolled from billets into such shapes as squares, rectangles, rounds, angles, channels, hexagons, and tees. In steel, "merchant bars" include rounds, flats, angles, squares, and channels that are used by fabricators to manufacture a wide variety of products such as furniture, stair railings, and farm equipment. Concrete reinforcing bar (rebar) is used to strengthen concrete in highways, bridges, and buildings.


The only commercial ore of aluminum, corresponding essentially to the formula Al2O3xH2O.


A squared-off long, oblong piece of metal (usually steel) used in construction. Commonly referred to as T-bars, I-beams, H-beams.


Raising a ridge on sheet metal. 


Various tests used to determine the toughness and ductility of flat rolled metal sheet, strip or plate, in which the material is bent around its axis or around an outside radius. A complete test might specify such a bend to be both with and against the direction of grain. For testing, samples should be edge filed to remove burrs and any edgewise cracks resulting from slitting or shearing. If a vice is to be used then line the jaws with some soft metal or brass, so as to permit a free flow of the metal in the sample being tested.


Chemical symbol Be. A gray metal found in beryl and bertrandite ores; brittle, but tough; lighter than all metals except magnesium and lithium. Used as unalloyed metal in nuclear reactors and weapons, and as an alloy with copper for electronic, aerospace, and automotive applications. Beryllium-copper is an alloy of copper and beryllium (about 3%) with fractional amounts of nickel or cobalt. These alloys have remarkable age-hardening properties, are extremely hard, and have good electrical conductivity, so they are used extensively in electrical switches and springs.


Rectangular semi-finished steel form (hot rolled from ingot or sheared from continuous caster's output) destined for further processing into rod, bar, structural, or tubing product. A billet is different from a slab because of its outer dimensions; billets are normally two to seven inches square, while slabs are 30-80 inches wide and 2-10 inches thick. Both shapes are generally continually cast, but they may differ greatly in their chemistry.


An alloy containing two elements, apart from minor impurities, as brass containing the two elements copper and zinc.


Chemical symbol Bi. A soft, course crystalline heavy metal with a silvery white color and pinkish tinge; usually produced as a by-product of copper, lead and other metals. Has a thermal conductivity lower than all other metals except mercury. Used as alloying agent but leading use is in pharmaceuticals.


A lightweight, thin, uncoated cold-reduced steel strip or sheet 12-to-32 inches wide with a dark oxide coloring prior to pickling that serves as the substrate (raw material) to be coated in the tin mill. Black plate ranges in thickness up to 275 lbs (base box weight). It is sold uncoated, enameled, painted, tin-coated, or terne-coated.


An early step in preparing flat-rolled metal for use by an end user. A blank is a section of sheet that has the same outer dimensions as a specified part to be stamped. Metal processors may offer blanking for their customers to reduce their labor and transportation costs as excess metal can be trimmed prior to shipment. (See STAMPING)


A defect in metal produced by gas bubbles either on the surface or formed beneath the surface while the metal is hot or plastic. Very fine blisters are called “pin-head” or “pepper” blisters.


Nearly square semi-finished steel product (hot rolled from ingot or sheared from continuous caster's output) whose cross-section is more than eight inches. Destined for further processing into rod, bar, or tubing product, but most commonly for such structural products as I-beams, H-beams, and sheet piling.


Sheets - A method of coating sheets with a thin, even film of bluish-black oxide, obtained by exposure to an atmosphere of dry steam or air, at a temperature of about 1000 0øF., generally this is done during box-annealing. Bluing of tempered spring steel strip; an oxide film blue in color produced by low temperature heating.


The coating of steel with a film composed largely of zinc phosphate in order to develop better bonding surface for paint or lacquer.


A piece of equipment used for bending sheet: also called a “bar folder.” If operated manually, it is called a “hand brake”; if power driven, it is called a “press brake.”


An alloy that is 70% copper, 30% zinc. One of the most widely used of the copper-zinc alloys; malleable and ductile; excellent cold-working but poor hot-working and machining properties; excellent for soft-soldering; good for silver alloy brazing or oxyacetylene welding, but fair for resistance or carbon-arc welding. Used for drawn cartridges, tubes, eyelet machine items, and snap fasteners.


Joining metals by fusion of nonferrous alloys that have melting points above 800°F. but lower than those of the metals being joined. This may be accomplished by means of a torch (torch brazing), in a furnace (furnace brazing) or by dipping in a molten flux bath (dip or flux brazing). The filler metal is ordinarily in rod form in torch brazing; whereas in furnace and dip brazing the work material is first assembled and the filler metal may then be applied as wire, washers, clips, bands, or may be integrally bonded, as in brazing sheet.


(For tempered steel) A method of testing hardened and tempered high carbon spring steel strip wherein the specimen is held and bent across the grain in a vice-like calibrated testing machine. Pressure is applied until the metal fractures at which point a reading is taken and compared with a standard chart of brake limitations for various thickness range. (See Bend Test)


A common standard method of measuring the hardness of certain metals. The smooth surface of the metal is subjected to indentation by a hardened steel ball under pressure or load. The diameter of the resultant indentation, in the metal surface, is measured by a special microscope and the Brinell hardness value read from a chart or calculated formula.


An alloy containing 90% copper and 10% tin. Used for screws, wire, hardware, wear plates, bushings, and springs; it is somewhat stronger than copper and brass, and has equal or better ductility.


A thin ridge or roughness left by a cutting operation such as in metal slitting, shearing, blanking or sawing. This is common to a No. 3 slit edge in the case of steel.


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The standard steel pipe used in plumbing. Heated skelp is passed continuously through welding rolls, which form the tube and squeeze the hot edges together to make a solid weld