Modeling kinetics of α→γ transformation in steels

The model for austenite growth during α→γ transformation in steels is developed in order to provide modeling of the transformation kinetics with regard to the steel microstructure parameters and the processing condition. Two cases of austenite growth are considered, which can take place during intercritical annealing of low carbon steels. In the simplest case the one-dimension austenite growth is considered to start from the boundary between cementite and ferrite phases and to proceed into ferrite. Herewith, the rate-controlling stage of the growth process is the carbon diffusion from the cementite/austenite boundary to the austenite/ferrite boundary. In the second case the austenite growth is considered to start from the boundary between ferrite grain and pearlite region, and then proceeds into pearlite. Herewith, the carbon diffusion in austenite in immediate proximity to the transformation front controls the growth rate. Agreement of the models suggested with the experimental data is demonstrated.