Modeling the austenite-ferrite diffusive transformation during continuous cooling on a mesoscale using Monte Carlo method

A Q-state Potts model is adopted to simulate the austenite-ferrite diffusive transformation during continuous cooling in a low carbon steel on a mesoscale with Monte Carlo method. The effects of the interfacial energy and the carbon diffusion on the phase transformation are both taken into account. The consideration of the interfacial energy effect makes the simulated ferrite grains polygonal. To simulate the carbon diffusion during the process of phase transformation, a random jumping based mesocopic diffusion model is developed. In this paper, the evolutions of the microstructure and the carbon concentration field are simulated. The simulation results of the effects of the cooling rate on the volume fraction of the ferrite and the ferrite grain size agree well with the experimental results. The simulation results show that increasing the cooling rate is an effective way to refine the microstructure. This Monte Carlo simulation technique provides a novel way for investigating the diffusive transformation on a mesoscale.