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<p>Edge cracking impedes the rolling productivity of AZ31B magnesium alloy. Although the classical Gurson-Tvergaard-Needleman (GTN) model is widely used for ductile damage prediction, it has limited applicability under complex stress states encountered during rolling, especially under shear-dominated loading or negative stress triaxiality. This study modifies the GTN model by introducing a stress-state-dependent weighting function, ω(η, μ), that explicitly couples stress triaxiality (η) and the Lode parameter (μ). The enhancement improves sensitivity to the full stress state and suppresses damage overestimation under shear and compression. Based on the modified model, a three-dimensional finite element model is developed to simulate edge cracking during rolling. The simulation results, validated by experiments, reveal that the susceptibility to edge cracking is governed by the synergistic evolution of edge tensile stress and stress triaxiality. The influence of key rolling parameters was systematically quantified. Increasing the roll diameter from 75 to 320&#xa0;mm reduced the maximum edge tensile stress by 76% (from 101 to 25&#xa0;MPa), thereby effectively suppressing edge cracking. A strong correlation between the maximum edge tensile stress and the crack length was conclusively established. This study provides an improved predictive framework and practical guidance for mitigating edge cracking during magnesium alloy rolling.</p>

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A modified GTN model coupled with Lode parameter and stress triaxiality for predicting edge cracking in rolling of AZ31B magnesium alloy

  • 期刊论文

  • 发表日期：

    2026年6月27日

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  • Lijun Wang,
  • Shuo Meng,
  • Lianyun Jiang,
  • Jintao Wang,
  • Jing Wang

摘要

Edge cracking impedes the rolling productivity of AZ31B magnesium alloy. Although the classical Gurson-Tvergaard-Needleman (GTN) model is widely used for ductile damage prediction, it has limited applicability under complex stress states encountered during rolling, especially under shear-dominated loading or negative stress triaxiality. This study modifies the GTN model by introducing a stress-state-dependent weighting function, ω(η, μ), that explicitly couples stress triaxiality (η) and the Lode parameter (μ). The enhancement improves sensitivity to the full stress state and suppresses damage overestimation under shear and compression. Based on the modified model, a three-dimensional finite element model is developed to simulate edge cracking during rolling. The simulation results, validated by experiments, reveal that the susceptibility to edge cracking is governed by the synergistic evolution of edge tensile stress and stress triaxiality. The influence of key rolling parameters was systematically quantified. Increasing the roll diameter from 75 to 320 mm reduced the maximum edge tensile stress by 76% (from 101 to 25 MPa), thereby effectively suppressing edge cracking. A strong correlation between the maximum edge tensile stress and the crack length was conclusively established. This study provides an improved predictive framework and practical guidance for mitigating edge cracking during magnesium alloy rolling.