A new phase field model has been developed which can simulate the austenite to ferrite (γ → α) transformation in low carbon steels at large space and time scales and involving multiple ferrite grain growth. The two-dimensional phase-field simulation shows that interface composition does not obey the local equilibrium assumption, while grain growth obeys a parabolic law for most of the transformation. The kinetics of continuous cooling transformation are successfully modelled. Results suggest that nucleation occurs both along austenite grain boundaries and within grains for high cooling rate transformations. Grain coarsening behind the transformation front is predicted. Two interesting phenomena, namely, interface acceleration, and solute enrichment behind the impingement fronts, are disclosed via this phase-field simulation.
- Phase field model
- Surface energy