Tool steels consist of various combinations of carbide-forming metals such as chromium, molybdenum, tungsten and vanadium. These iron-based alloys have a relatively high carbon content to increase strength and form carbides.

Substitute solutes such as nickel and cobalt are added for high temperature strength. Carbide-forming metals such as chromium, molybdenum, tungsten and vanadium are added to improve hardness and wear resistance.