Dynamic recrystallization, twinning behaviors and mechanical response of pre-twinned AZ31 Mg alloy sheet along various strain paths at warm temperature

In this study, AZ31 Mg alloy sheet was pre-twinned at room temperature along the transverse direction (TD) to introduce {10–12} tensile twins. The uniaxial tensile experiment was conducted at 200 °C to investigate the dynamic recrystallization, twinning behaviors and mechanical response. The strain paths tilted angles of 0°, 15°, 30°, 45°, 60°, 75° and 90° in respect to the rolling direction (RD) on the RD-TD plane were considered. Results revealed that the strain path has significant effects on the microstructural evolution and mechanical response at warm temperature. When the strain path tilts were 0°, 15°, 30°, 45° and 60° with the RD, continuous dynamic recrystallization (CDRX) was the main mechanism to coordinate strain. The detwinning dominated the microstructural evolution but retarded by CDRX for the pre-twinned sample with a strain path angle of 75°. Detwinning and CDRX played an important role on the microstructural evolution in the pre-twinned sample when the strain path was tilted 90°. Additionally, the effect of CDRX on {10–12} twinning and three types of {10–12} tensile twin behaviors were discussed. Both strengthening and weakening effects were observed in pre-twinned samples.