Although molybdenum is used alone in some alloys, often it is supplemented by other elements, particularly nickel or chromium or both. The addition of nickel increases the ductility of steel while allowing it to maintain its strength . Vanadium Addition of this element to steel promotes fine grain structure when the steel is heated above its critical range for heat treatment. It also imparts toughness and strength to the metal. This element is used mostly in steels designed for metal cutting tools.
Tungsten steels are tough, hard, and very resistant to wear.
Cobalt The chief function of cobalt is to strengthen the ferrite.