The Effect of Twins on Mechanical Properties and Microstructural Evolution in AZ31 Magnesium Alloy during High Speed Impact Loading

In order to investigate the influence of twin on mechanical behavior and microstructural evolution of magnesium alloys under impact loading, high-speed impact tests of magnesium alloys with different twin densities were conducted by Split Hopkinson Pressure Bar under impact pressures of 0.3, 0.5, and 0.7 MPa with deformation temperatures of 150, 200, 250, 300, and 350 °C. The yield strength of magnesium alloy is significantly enhanced by twins under high-speed impact loading. At low-temperature impact deformation, twinning and deformation shear bands are the main accommodation mechanisms for un-twinned magnesium alloy, while with respect to the twinned magnesium alloy, dynamic recrystallization (DRX) could participate in plastic deformation. The appearance of twins could reduce the recrystallized temperature and the critical strain for DRX. The twinned magnesium alloy is benefit for texture weaken during high impact loading. The maximum pole density monotonic decreases with increasing recrystallization fraction and decreasing twin density.