MODELING REAUSTENITIZATION FROM FERRITE CEMENTITE MIXTURES IN FE-C STEELS

The formulation of austenite which occurs upon heating low-alloy steels is known as reaustenitisation. Phase transformation theory applicable to the formulation of austenite from ferrite/cementite mixtures in Fe-C steels is described. The assumption of local equilibrium is made. Diffusion of carbon in cementite and ferrite is ignored. Under these assumptions, the process is controlled by the diffusion in austenite, the growing phase. Exact solutions to the equations are compared with results obtained using the finite difference method, for one-dimensional growth. It is found that the finite difference method is subjected to numerical inaccuracies which can be considerable. A method to circumvent this problem is described. Reverse time-temperature-transformation diagrams for Fe-C steels are presented.