Comparison of Isotropic and Anisotropic Yield Criteria Models in Quenching Residual Stress of Magnesium Alloys

Simulation model accuracy of quench induced residual stress in wrought magnesium alloy Mg‒Gd–Y–Zr–Ag–Er is tested by applying both isotropic and anisotropic criteria models in residual stress FEM simulation. Both hexagonal close-packed (HCP) lattice structure and asymmetry are considered in the manufacturing process. The distributions of residual stress in isotropic and anisotropic criteria models differ both in distribution and in value, which is due to stress-strain nonuniformity in extrusion direction (ED) and long transverse direction (LTD). Comparing the experimental and predicted errors of the two models, the anisotropic model improves the prediction accuracy by 8.3% in ED and 4.8% in LTD. Residual stress in LTD is always larger than that in ED by the XRD method, and the average deviation between the XRD method and the hole-drilling method is reduced through electropolishing.