Modified male die rapid gas blow forming of fine-grained Mg alloy AZ31B thin sheet

Abstract

Gas blow forming of a commercial, fine-grained, 0.6-mm-thick Mg alloy AZ31B thin sheets under high strain rates to decrease the forming time was investigated in the present work. An innovative male die rapid gas blow forming method was developed. Using this new method and stepwise pressurization profiles, alloy sheets were successfully deformed to form shallow rectangular pans. Deformation characteristics of rapid gas blow forming were discussed. Results indicated that the proposed process significantly reduces the forming time and that a shallow rectangular pan may be formed under a maximum average strain rate of approximately 10−2 s−1. A 10-mm-high rectangular pan was formed in <109 s. Sheet thinning was improved by modified male die forming. The fillet radius of the rectangular pan was found to be one of the key factors that influence the rapid gas blow forming time. Strain-enhanced grain growth was the major growth mechanism during rapid gas blow forming. Grain growth and cavitation were not serious problems during rapid gas blow forming.