Alloy Steel is a metal alloy consisting mostly of iron, in addition to small amounts of carbon, depending on the grade and quality of the steel.

Alloy steel is any type of steel to which one or more elements besides carbon have been intentionally added, to produce a desired physical property or characteristic. Common elements that are added to make alloy steel are molybdenum, manganese, nickel, silicon, boron, chromium, and vanadium.