Effect of cold forging and static recrystallization on microstructure and mechanical property of magnesium alloy AZ31

Abstract

We perform a cold forging and annealing technique on Mg alloy AZ31 and investigate the impact on microstructure evolution and mechanical property. In particular, we focus on how twin and static recrystallization behave during the forging process followed by the annealing. Interestingly, we find that a large number of thick-lenticular (1012) twins emerge at initial stage of deformation and subsequently evolve into narrow-band (1011) and (3032) twins. The transformable twins are found to be crucial for inducing static recrystallization via providing recrystallization sites and refined grains. Moreover, the alloy forged at room temperature and annealed at 623 K is found to have optimal microstructure due to the complete recrystallization and therefore exhibit the highest micro-hardness, largest compressive strength, and most significantly enhanced compressive ratio. The improved mechanical properties are comparable or even superior to those of the alloy deformed using other techniques, rendering the cold forging a promising way for further tailing properties of Mg alloy. © 2010 The Japan Institute of Metals.