In theory, the maximum hardness and toughness of steel can be achieved with a simple alloy of pure iron and carbon. In practice, more alloying elements are needed because they facilitate the steelmaking processes and enable practical heat treatment. In other words, an iron-carbon alloy works in the laboratory; alloy steels are needed in real life.
European steel factories produce heat-treatable steel plates according to the European standard EN10132 “Cold rolled narrow steel strip for heat treatment. Technical delivery conditions”. The standard defines the properties of plates and the chemical compositions of steel grades. It includes 80CrV2, whose chemistry is as follows: 0.75–0.85%C, 0.15–0.35%Si, 0.3–0.5%Mn, <0.025%P, <0.025%S, 0.4–0.6%Cr, 0.15–0.25%V
Si and Mn are mandatory processing additions used during steel melting, while P and S are harmful impurities. In this respect, it is like ordinary carbon steel. Cr and V are the alloying elements that make 80CrV2 steel unique. The main job of Cr is to increase hardenability, but it also decrease the initial austenite grain size, while V prevents austenite grain growth during hardening. As a result, hardened 80CrV2 has an exceptionally small prior austenite grain size, which enables maximum toughness.