Effect of Zn on workability and coupled CA-FE simulation for DRX of Mg-8Gd-4Sm-0.5Zr alloy during hot deformation

In this paper, the effect of Zn on the dynamic precipitation phase and DRX grain size of Mg-8Gd-4Sm-0.5Zr alloy was investigated by using OM, SEM, and TEM. The effect of Zn on the hot workability was investigated by constructing the DMM model. The variation of DRX behavior and microstructure evolution of the two alloys were investigated by constructing the CA-FE coupled model. The test was conducted using the Gleeble-1500 testing machine at deformation temperatures of 350–470 °C and strain rates of 0.002–1 s −1 . The results show that the addition of Zn promotes the type and number of dynamically precipitated phases and refines the DRX grain size. The critical strain ε c decreases with the addition of Zn, and the dynamic recrystallization level of 1Zn alloy is higher. The addition of Zn reduces the instability region and increases the workability region. The plastic deformability is optimized in the high-temperature P 1 region. The nucleation site of DRX grains simulated by CA-FE coupling is closely related to the dislocation density distribution. The DRX grains nucleate at grain boundaries and gradually expand into the surrounding grains. The standard deviation (S.D.) and the distribution of different sizes of DRX grains gradually increase with increasing temperature. Meanwhile, the relative errors between the simulated and experimental values for predicting the DRX grain sizes of the two alloys are mostly less than 10 %. It is verified that the coupled CA-FE simulation can accurately predict the variation of dynamic recrystallization behavior and microstructure evolution of materials under different deformation conditions.