Effect of annealing on the microstructure and mechanical properties of Mg-9Al% alloy plates processed with symmetrical and asymmetrical rolling

In this study, the Mg-9Al% plates with a total of approximately 50% thickness reduction corresponding to 0.76mm per pass, were obtained by symmetrical and asymmetrical rolling. The effect of different annealing temperature and corresponding holding time on the microstructure and mechanical properties were investigated. Key results showed that in the as-rolled state, the plates processed by asymmetrical rolling had smaller grain size and higher hardness value and ultimate tensile strength than symmetrical rolling. After annealing treatment, the hardness value of the both plates decreased due to the internal stress released. A good combination of strength and ductility were achieved for symmetrical and asymmetrical processed plates at 350℃ for 1 hour and 325℃ for 1 hour, respectively, which can be attributed to the static recrystallization and weakening the basal texture. These results show that the appropriate annealing is an effective way to enhance the mechanical formability of plastic deformed Mg plates.