Study of the Microstructure of AZ31B Magnesium Alloy Under High Strain Rate Deformation

In order to investigate the microstructure evolution under high strain rate deformation of magnesium alloy, AZ31B magnesium alloy was impacted by Split Hopkinson Pressure Bar within the strain rates of 496s(-1) to 2120s(-1), then the specimens were observed by optical microscopy. The results show that when the strain rate are relatively low (496s(-1)-964s(-1)), the microstructure is predominated by high density of twinning, while increase the strain rate to 2120s(-1) the volume fraction of twins is decreased. This implies that at relatively lower strain rate the deformation mechanism of AZ31B magnesium alloy under impact loading is twinning; increasing the strain rate the prismatic slip and pyramidal slip may be active besides twinning.