Effect of pre-existing [formula omitted] extension twins on mechanical properties, microstructure evolution and dynamic recrystallization of AZ31 Mg alloy during uniaxial compression

Abstract

AZ31 Mg alloy plates were pre-compressed at room temperature along the transverse direction (TD) to introduce {101¯2} extension twinning. Mechanical properties, microstructure evolution and dynamic recrystallization (DRX) mechanisms of twinned samples containing pre-existing twins during uniaxial compression were investigated and compared to those of as-received samples. The results indicated that compared to that of as-received sample compressed along the rolling direction (RD), the yield stress of twinned sample was dramatically increased at from room temperature to 200 °C. In contrast, when compressing along the normal direction (ND), the yield stress of twinned sample was greatly decreased at from room temperature to 200 °C. With the further increase of temperature, the as-received and twinned samples exhibited similar compression flow curves and obvious DRX had taken place. Continuous dynamic recrystallization (CDRX) was the main DRX mechanism in the as-received sample compressed along ND at 200 °C. Twin assisted DRX besides CDRX was also initiated in the as-received sample compressed along RD and in the twinned sample compressed along ND or RD at 200 °C. DRX mechanism was changed to discontinuous dynamic recrystallization (DDRX) in the as-received and twinned samples with the further increase of temperature.