Alloy - The mixture of any element with a pure metal. However, there are several elements regularly occurring in plain carbon steel as manufactured, such as carbon, manganese, silicon, phosphorous, sulfur, oxygen, nitrogen and hydrogen. Plain carbon steel is therefore an alloy of iron and carbon and these other elements are incidental to its manufacture. Steel does not become alloy steel until these elements are increased beyond their regular composition for a specific purpose, or until other metals are added in significant amounts for a specific purpose.

Age Hardening - Precipitation hardening; a process of aging that increases hardness and strength and ordinarily decreases ductility. Age hardening usually follows rapid cooling from solution heat treatment temperatures or cold working.

Aging - 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.

Alloy Steel - Steel is considered to be alloy steel when the maximum of the range given for the content of alloying elements exceeds one or more of the following limits: Manganese 1.650/0, silicon,.60%, copper,.600/0, or in which a definite range or a definite minimum quantity of any of the following elements is specified or required within the limits of the recognized field of constructional alloy. Steels: Aluminum, chromium up to 3.9~, cobalt, columbium, molybdenum, nickel, titanium, tungsten, vanadium, zirconium, or any other alloying element added to obtain a desired alloying effect.

Annealing - A process involving high-temperature heating and cooling of the as-rolled cold rolled steel substrate to make it softer and more formable.

AR 400 Steel - This is a steel with an even higher yield strength and it is more difficult to form than hi-tensile steel. HEIL uses this steel in flat plates mainly on the floors and tailgates of custom bodies. It has a minimum yield strength of 145,000 psi and a Brinell hardness of 400.