Stress-strain hysteresis and strain hardening during cyclic tensile test of Mg-0.6at%Y alloy

The Mg-0.6at%Y alloy having an average grain size of 180µm and random texture was subjected to cyclic tensile tests at room temperature. Tensile tests were performed at a strain rate of 1×10−3s−1 for 10 cycles with the peak stress of 40, 70, and 100MPa with reference to the 0.2% proof stress of 68MPa. Hysteresis loops and cyclic strain hardening were observed in all peak stress cases. The observation of slip traces and twin types suggested that the hysteresis behavior was due to synchronous movement of basal slip and anomalous {101̅2} twinning, and that the cyclic strain hardening was due to non-basal slip. Prismatic slip led to cyclic strain hardening when peak stress was below the proof stress, and both prismatic and pyramidal slip promoted larger cyclic strain hardening when peak stress was increased over the proof stress.