KINETICS OF AUSTENITE TO FERRITE TRANSFORMATION IN 3 MASS-PERCENT MN LOW-CARBON STEELS

The kinetics of isothermal austenite to ferrite transformation in low carbon steels was studied theoretically. The transformation rates were calculated in steels containing 3 mass% Mn assuming various modes of transformation, i.e. massive, paraequilibrium and ternary (Fe-C-Mn) lo cal equilibrium. A crude comparison was made with experimentally obser ved microstructures. The transformation is likely to occur accompanyin g carbon diffusion not only in the (alpha+gamma) two phase field, but also in the alpha single phase field. In contrast, diffusion of Mn is unlikely to occur, or may not play a major role in the transformation.