Microstructure and mechanical properties of AZ31 magnesium alloy processed by cyclic closed-die forging

摘要

AZ31 alloy was subjected to cyclic closed-die forging (CCDF) under various processing conditions. Then tensile tests were carried out to investigate the relationship between tensile properties and microstruc-tural parameters that include grain size and the texture generated by CCDF. With increasing the number of CCDF passes, a finer grain size and more homogeneous microstructure but stronger basal texture are obtained along with significant improvement in both strength and ductility. An average grain size of ~5.2 μm is achieved after five passes at 350 °C AZ31 alloy exhibits a yield strength of 173 MPa and elongation of 15.3% compared to initial 42 MPa and 10.2%, respectively. On the other hand, in the samples processed at 350 °C, yield strength is higher than those of samples processed at higher temperatures, but elongation is smaller. This can be ascribed to difficult basal slip caused by the textures in which the basal plane is oriented parallel to the tensile direction.