Hardened, tempered, polished and blued or yellow flat steel with dressed edges. Carbon content about1.00%. Material has to possess good flatness, uniform hardness and high elasticity.

ACID-BRITTLENESS

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

ACID-PROCESS

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

ACID-STEEL

The term has no reference to the acidity of the steel. (See Acid Process.)

AGE HARDENING

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

AGING

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

AIR COOLING

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

AIR HARDENING STEEL

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 ofchromium, nickel, molybdenum and manganese are effective toward this end.

AISI STEELS

Steels of the American Iron and Steel Institute. Common and alloy steels have been numbered in asystem essentially the same as the SAE. The AISI system is more elaborate than the SAE in that allnumbers are preceded by letters: “A” represents basic open-hearth alloy steel, “B” acid Bessemer carbonsteel, “C” basic open-hearth carbon steel, “CB” either acid Bessemer or basic open-hearth carbon steel,“E” electric furnace alloy steel.

ALCLAD

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

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ALLOTROPY

(See Polymorphism)

ALLOY

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

ALLOY STEEL

Steel containing substantial quantities of elements other than carbon and the commonly-accepted limitedamounts of manganese, sulfur, silicon, and phosphorous. Addition of such alloying elements is usuallyfor the purpose of increased hardness, strength or chemical resistance. The metals most commonly usedfor forming alloy steels are: nickel, chromium, silicon, manganese, tungsten, molybdenum and vanadium.“Low Alloy” steels are usually considered to be those containing a total of less than 5% of such addedconstituents.

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 or5% of tin. This alloy is used in coinage, springs, turbine, blades, etc.

ALPHA IRON

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

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

AMORPHOUS

Noncrystalline.

ANNEALING

A heating and cooling operation implying usually a relatively slow cooling. Annealing is a comprehensiveterm. The process of such a heat treatment may be: to remove stresses; to induce softness; to alterductility; toughness; electrical magnetic, or other physical properties; to refine the crystalline structure; toremove gases; to produce a definite micro-structure. In annealing, the temperature of the operation andthe rate of cooling depend upon the material being heat treated and the purpose of the treatment.