Features and applications of common carbon steel alloys

Low carbon steels generally contain less than 0.25% carbon and cannot be strengthened by heat-treating (strengthening can only be accomplished through cold working). The low carbon material is relatively soft and weak, but has outstanding ductility and toughness. In addition, it is machineable, weld-able, and is relatively inexpensive to produce.

Medium carbon steels have carbon concentrations between 0.25% and 0.60%. These steels may be heat-treated by austenizing, quenching, and then tempering to improve their mechanical properties. On a strength-to-cost basis, the heat-treated medium carbon steels provide tremendous load carrying ability.

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.