The eutectoid phase transition in the iron carbon system takes place at 727 C. The three components in equilibrium at this temperature are Austenite, g, with the composition Fe - 0.77 wt % C, Ferrite, ...

At cooling rates faster than 140 C/s the transition is to a metastable material known as martensite. Between 35 and 140 C/s the system at room temperature is a mixture of these two materials. The ...