Abstract:In order to discover the relationship between the twinning deformation and microstructure in Mg alloy, describing twinning by pseudo-slip mode, the crystal plastic constitutive relation including slipping and twinning was established. And the Newton-Raphson iteration method was developed with the shear strain rate directly as the basic variables of iteration. The deformation behaviors of extruded Mg alloy loaded by uniaxial tension and compression along the extrusion direction were simulated using the finite element model of polycrystal based on voxel algorithm. The simulation results show that the macroscopic hardening behaviors predicted using the proposed model are in good agreement with the experimental results, and there are the same evolutions of polycrystalline texture during testing and simulating for Mg alloy. The statistical analyses of principal physical variables show that the proposed constitutive model is available to demonstrate the inhomogeneous characteristic of spatial distribution of stress-strain, the fraction of twinning in polycrystal, but there is a short age of the explicit relatedness of the volume fraction of twinning with respect to grain size, the misorientation between grain boundary plane normal and loading direction, the grain boundary misorientation angles in polycrystal, respectively. It is shown that the inhomogeneous state of unique stress resulted from the inhomogeneity of microstructure is not the reason for the strong relatedness between twinning deformation and microstructure.