Phase-field Simulation of Habit Plane Formation during Martensitic Transformation in Low-carbon Steels

摘要

The origin of the habit plane of the martensite phase (α') in low-carbon steels is elucidated by three-dimensional phase-field simulations. The cubic → tetragonal martensitic transformation and the evolution of dislocations with Burgers vector a_(α')/2〈111〉_(α') in the evolving α' phase are modeled simultaneously. By assuming a static defect in the undercooled parent phase (γ), we simulate the heterogeneous nucleation in the martensitic transformation. The transformation progresses with the formation of the stress-accommodating cluster composed of the three tetragonal domains of the α' phase. With the growth of the α' phase, the habit plane of the martensitic cluster emerges near the (111 )_γ plane, whereas it is not observed in the simulation in which the slip in the α' phase is not considered. We observed that the formation of the (111 )_γ habit plane, which is characteristic of the lath martensite that contains a high dislocation density, is attributable to the slip in the α' phase during the martensitic transformation.