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

抄録

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.