Simulation study on microstructure evolution during the backward extrusion process of magnesium alloy wheel

Abstract

Magnesium (Mg) alloy wheels can reduce emissions in the context of environmental protection. Further study on Mg alloy wheels is required in light of the enormous automotive market since it is still unknown how the microstructure is evolving for the backward extrusion (BE) process of Mg alloy wheels. In this paper, a numerical model of the Mg alloy wheel was established based on industrial production, and the physical field and dynamic recrystallization (DRX) evolution of cylindrical billet and truncated cone billet on the forming process of Mg alloy wheels were analyzed, as well as the accuracy of the simulation results was verified by physical simulation in laboratory conditions and industrial production. The wheel bottom is in adiabatic temperature rise and the temperature is higher than that of the rim during the wheel forming process, while the effective strain distribution and uniformity are lower than that of the rim. The DRX volume fraction and grain size are consistent with the effective strain evolution. The truncated cone billet can effectively improve the DRX volume fraction and refine the grain size of the wheel compared with the cylindrical billets. This work can provide theoretical guidance for the BE process of Mg alloy wheels.