Invited review: Carbides and nitrides in steel

The crystal chemistry and the occurrence of carbides and nitrides in steels are reviewed. The characteristics of nitrogen are emphasised and are related to the behaviour of carbon. The importance of oxygen as an interstitial element and its influence on the stability of interstitial alloy phases in which it is a minor constituent are discussed. Iron carbides and nitrides, alloying element carbides and nitrides, and then interactions between alloying elements and carbon and nitrogen in solution in iron are considered in turn.