Flow behavior and microstructure of ZK60 magnesium alloy compressed at high strain rate

Flow behavior and microstructure of a homogenized ZK60 magnesium alloy were investigated during compression in the temperature range of 250–400 °C and the strain rate range of 0.1–50 s−1. The results showed that dynamic recrystallization (DRX) developed mainly at grain boundaries at lower strain rate (0.1–1 s−1), while in the case of higher strain rate (10–50 s−1), DRX occurred extensively both at twins and grain boundaries at all temperature range, especially at temperature lower than 350 °C, which resulted in a more homogeneous microstructure than that under other deformation conditions. The DRX extent determines the hot workability of the workpiece, therefore, hot deformation at the strain rate of 10–50 s−1 and in the temperature range of 250–350 °C was desirable for ZK60 alloy. Twin induced DRX during high strain rate compression included three steps. Firstly, twins with high dislocation subdivided the initial grain, then dislocation arrays subdivided the twins into subgrains, and after that DRX took place with a further increase of strain.