Coupled simulation of the influence of austenite deformation on the subsequent isothermal austenite-ferrite transformation

The influence of austenite deformation on the subsequent isothermal austenite-ferrite transformation in binary Fe-C alloys is simulated by coupling a Q-state Potts Monte Carlo (MC) method with a crystal plasticity finite element method (CPFEM). The initial deformed microstructure characteristics induced by the plane strain hot compression are simulated using the CPFEM. Based on a linear interpolation approach, these characteristics, which include the stored energy and the orientation, are mapped onto a regular hexagonal lattice as the initial parameters of the MC simulation. The simulation results reveal that the plastic deformation increases the equilibrium ferrite volume fraction and accelerates the transformation kinetics. The regions with high stored energy at austenite grain interiors and boundaries and the extended austenite grain boundary area induced by plastic deformation can increase the effective ferrite nucleation sites. The effects of plastic deformation on the long-range diffusion of carbon atoms in austenite and short-range diffusion of iron atoms across the austenite/ferrite interface are investigated. This simulation technique provides a novel way for investigating the austenite-ferrite transformation under deformation conditions on a mesoscale.