Crystal plasticity finite element modeling of twin band formation and evolution together with the macroscale mechanical responses of hexagonal metals

Abstract

Deformation twinning is one of the major plastic deformation modes of hexagonal metals. In this study, a new system of crystal plasticity finite element models is developed, with the cooperative interactions of dislocation slip and deformation twinning comprehensively involved. The obtained stress-strain curves for several differently-orientated Mg single crystals match well with experimental results, and the formation and thickening features of twin bands are captured. Simulation results reveal that (1) some thin twin bands are firstly formed in the shearing direction of the twinning plane, because of the much lower twinning resistance than that in the normal direction; (2) the softening and hardening of the twinning resistance play a critical role in the anisotropic mechanical response. By optimizing the twinning activation behaviors, the favorable interactions of twinning and dislocation slip can occur and the plastic deformation ability can be improved.