Hot tensile deformation behaviors and a fracture damage model of the Mg-Gd-Y-Zn-Zr alloy

In this study, the hot deformation of Mg-9Gd-4Y-2Zn-0.5Zr alloy was studied by the hot tensile test conducted at various temperatures (350 degrees C-500 degrees C) and strain rates (0.0001-0.1s(-1)). Furthermore, the relationship among the peak stress, the fracture strain, fracture morphology and soften behavior was discussed, and a fracture damage model was pro-posed to predict the fracture failure. The results were as follows. The soften behaviors, including the twin being replaced by multi-slip and the occurrence of DRX become more obvious with the decrease of Z (Z = <(epsilon) over dot> exp(Q/RT)) value, which leads to the decrease of the RT strain hardening exponent n determining the peak stress and the increase of the strain-rate hardening exponent m determining the fracture strain. The greater the n, the greater the peak stress; the greater the m, the greater the fracture strain. The trans-formation of the fracture morphology with the decreasing Z value is cleavage surfaces -> coexistence of cleavage surfaces and dimple -> dimple. The proposed fracture damage model is in good agreement with the experimental results. (C) 2022 The Authors. Published by Elsevier B.V.