Microstructure evolution and deformation behaviors of AZ31 Mg alloy with different grain orientation during uniaxial compression

Effect of grain orientation on deformation behaviors and microstructure evolution of rolled AZ31 Mg alloy during uniaxial compression have been investigated as a function of temperature and strain rate. Rectangular prism samples of rolled AZ31 Mg alloy were compressed along different directions, with the compression axis parallel to the sheet normal direction (ND), the 45° direction and the rolling direction (RD), referred to as ND, 45° and RD sample, respectively. The results indicated that the compression flow curve, the strength and the strain hardening rate were highly anisotropic with respect to the initial grain orientation at various temperature and strain rate, especially at low temperature and low strain rate. This is due to the fact that the crystallographic slips dominate the early deformation in ND sample, the crystallographic slips and {10-12} twinning collectively dominate the early deformation in 45° sample while the {10-12} twinning dominates the early deformation in RD sample at low temperature. The anisotropies gradually decreased with the increasing temperature, which is due to that the dislocation slips gradually begin to dominate the deformation. Obvious dynamic recrystallization (DRX) had taken place with the increasing temperature. CDRX and DDRX were initiated in the ND sample during compressing at elevated temperature. In addition to CDRX and DDRX, {10-12} twin related DRX was also initiated in the RD sample during compressing at elevated temperature.