Crystal Plasticity Modeling of Pure Magnesium Considering Volume Fraction of Deformation Twinning

Abstract

In this study, a novel crystal plasticity model for pure magnesium involving the deformation twinning is presented. The deformation twinning is an important deformation mechanism of magnesium and other HCP metals. The deformation twinning has two important issues: first, the large rotation of crystal lattice caused by twinning occurs. Second, in the crystalline scale, the twinned and untwinned regions may simultaneously exist in a grain. Therefore, a crystal plasticity analysis of magnesium should introduce both of them, and the present framework takes these two key features into account. To represent the second issue, the volume fraction of deformation twinning is considered. This paper provides a framework of crystal plasticity model involving the effect of tensile twinning, and a numerical example is conducted to evaluate the evolution of volume fraction of twinned region. It is shown that the present scheme can describe the mixed state of twinned and untwinned regions. The obtained results suggest that the twinned and untwinned regions simultaneously exist even under the large deformation and the volume fraction of twinned region should be considered.