Research on Two-stage Gas Bulging Forming of a Rolled Magnesium Alloy AZ31

The Two-Stage gas bulging forming of a rolled magnesium alloy AZ31 under the conditions of 523 K,0.3 MPa and 623～673 K,0.55～0.7 MPa,was investigated respectively.The wall thinknesses strains are different in a single gas bulging forming pan.The stress in the second-stage forming is much lower than that in the first-stage,and softening is observed.Optical microstructral observation and SEM observation show that in the first stage,the grain refinement after forming is obvious due to dynamic recrystallization and it is virtually beneficial to the second stage.During the second forming stage,grain boundary sliding functions mainly and accompanied with some inner-grain slide.