A study on material modeling to predict spring-back in V-bending of AZ31 magnesium alloy sheet at various temperatures

AZ31 magnesium alloy sheets are usually performed at high temperatures of 200–250°C due to their unusual hexagonal close-packed structure and low ductility at room temperature. In this study, to predict V-bending/unbending spring-back of AZ31 magnesium alloy sheets subjected to high temperatures, a modified kinematic/isotropic hardening model considering the unusual plastic behavior of the magnesium alloy sheets, which follow the modified Johnson–Cook (JC) model, was used by way of a user-material subroutine, using an explicit finite element code. The simulation results from the modified hardening model at room temperature are compared with measurements of tension/compression and compression/tension tests. The modified JC model was then applied to predict tension/compression and compression/tension curves at high temperatures. Finally, an actual V-bending/unbending process for an AZ31 magnesium alloy sheet at high temperatures was performed to verify the spring-back angle, and this angle was then compared with spring-back angle predictions of the FE simulation. The proposed hardening model showed good agreement between simulation results and corresponding experiments.