Effect of differential speed rolling on the room and elevated temperature tensile properties of rolled AZ31 Mg alloy sheets

Abstract

Cast-rolling AZ31 Mg alloy sheets were manufactured at four rolling speed ratios of 0.8, 1.0, 1.2 and 1.3. The results show that the basal texture can be weakened by differential speed rolling (DSR). The AZ31 alloy sheet manufactured at a speed ratio of 1.2 exhibits a fine microstructure with an average grain size of 10.3μm. The yield strength, ultimate tensile strength and elongation-to-failure at this speed ratio are 145MPa, 240MPa and 28.5% at room temperature, respectively. These parameters mainly benefit from the fine grains and weakened basal texture. The AZ31 alloy sheets processed by the DSR exhibit a remarkable improvement in elongation-to-failure compared with the AZ31 alloy sheets processed by equal speed rolling (ESR) primarily due to the weakened basal texture at room temperature. However, the difference in elongation-to-failure of the AZ31 alloy sheets processed by the ESR and DSR decreases at elevated temperatures, which can be attributed to the weakening of the influence of basal texture, with probable activation of non-basal slips and grain boundary sliding (GBS). The results obtained here will shed light on some DSR methods, which is critical to the development of Mg alloys with high mechanical properties.