This is the solid interstitial solution of carbon in gamma iron (FeC), which is stable only within a particular range of composition and temperature. and is non-magnetic. It has a FCC lattice in which the interstices are larger than in the BCC lattice, because of which the solubility of carbon in FeC is much higher and attains 2.14%. Austenite is ductile and has a higher strength than ferrite (HB 160-200) at a temperature 20-25°C. On cooling below 723°C it starts transforming into ferrite and which is magnetic and cementite to form the eutectoid pearlite, together with free ferrite or free cementite, depending on whether the carbon content is less or greater than 0.87% respectively. We may note that the austenite in a eutectoid steel is unstable at all temperatures.
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