Simulation research on the rotating back extrusion process for magnesium alloy wheel

Abstract

The flow stress model, the dynamic recrystallization (DRX) model, the grain growth (GG) model and the Normalized Cockcroft-Latham (NC-L) ductile fracture criterion are integrated into the finite element (FE) model to simulate the physical field and DRX evolution of the AZ80 magnesium (Mg) alloy wheel forming process by the rotating back extrusion (RBE) process. The deformation behavior of the AZ80 Mg alloy wheel during the forming process is calculated quantitatively when the angular velocity (\(\omega\)) is 0 to 80°/s. Findings revealed that the RBE process increases the deformation heat and effective strain in the forming process of the wheel, and refines the grain size of the whole wheel. However, excessive angular velocity (\(\omega\) > 40°/s) is not conducive to the DRX of the wheel bottom, which makes the grain at the wheel core grow abnormally and reduces the uniformity of the microstructure distribution at the wheel bottom. The damage factor value at the upper rim increases with the increase in \(\omega\), i.e., the tendency of the upper rim to crack increases. Therefore, the \(\omega\) of the Mg alloy wheel produced by the RBE process within the scope of this study should be set at 40°/s. The RBE process of the Mg alloy wheel can provide a new idea for the plastic forming of Mg alloy wheels.