Austenite

Austenite is a solid solution of carbon and iron that exists in steel above the critical temperature of 1333°F (about 723°C). It is named after Sir W.C. Roberts-Austen. Its face-centred cubic (FCC) structure allows it to hold a high proportion of carbon. As it cools, it breaks down into other materials such as pearlite (a mixture of ferrite and cementite), martensite and bainite. The rate of cooling determines the relative proportions of these materials and therefore the mechanical properties (e.g. hardness, tensile strength) of the steel.

The addition of certain other metals, such as manganese, nickel and chromium, can cause the austenitic structure to survive at room temperature, resulting in austenitic steel.