Evaluation and prediction of the forming limit of AZ31B magnesium alloy sheets in a cross-shaped cup deep drawing process

Abstract

In this study, the formability of AZ31B magnesium alloy sheets was investigated through experimental and numerical approaches. Tensile tests and limit dome height tests were carried out at several temperatures between 25 °C and 300 °C to obtain the mechanical properties and forming limit diagram (FLD). The interfacial heat transfer coefficient between two adjacent tools, and the convection coefficient were estimated by comparing the tool temperatures obtained from trial heat transfer analyses with actual measured data. The FLD-based criterion considering the strain path and the blank temperature was used to predict by finite element analysis (FEA) the forming limit in a cross-shaped cup deep drawing process. A comparison of the FEA and experimental data showed that this criterion was very useful and reasonable. In particular, the temperature of each forming tool that provided the best formability of AZ31 sheets was determined by coupled temperature-deformation analyses. A practical method that can greatly reduce the forming time by increasing the punch speed during the forming process was suggested.