Multi-phase-field modeling of diffusive solid phase transition in carbon steel during continuous cooling transformation

Abstract

Abstract The growth kinetics and final morphology of ferrite ( α ) grains are characterized by interfacial energy and boundary mobility, which strongly correlate to constituent phase, misorientation angle and the specific orientation relationship at the α / γ interface, such as the Kurdjumov–Sachs (KS) orientation relationship. In a previous phase-field simulation of the α grain growth, interfacial energy and mobility is assumed to be constant. Therefore, the simulated morphology of α grains is equiaxed. In this study, the multi-phase-field (MPF) simulation of α grain growth during γ → α transformation is performed to study the effects of phase- and misorientation-dependent interfacial energy and boundary mobility on the growth kinetics of α grains. The phase and misorientation dependence of interfacial energy is simply described by the Read–Shockley equation. Our results indicate that the phase- and misorientation-dependent interfacial energy induces α grain growth along the γ grain boundary so as to reduce the total interfacial energy of the system. Furthermore, by considering both the phase- and misorientation-dependent interfacial energy and boundary mobility, the plausible growth kinetics of α grains can be reproduced and the morphology of α grains can be quite similar to the α grain morphology determined by the KS orientation relationship.