Edge cracks are a type of damage that critically affect the quality and properties of rolled Mg alloys sheet. Accurate damage prediction plays a key role in root cause analysis and process optimization. Although the phenomenological prediction of edge damage in Mg alloy rolling has made some progress so far, the prediction of edge crack behavior and analysis of the mechanisms of crack formation and evolution during rolling have not yet been well reported. In this research, a modified Gurson-Tvergarrd-Needleman (GTN) model was proposed by modifying the growth mode of shear damage. The three-dimensional single-unit finite element (FE) model test results indicated that the proposed model improved the accuracy of the fracture response under negative stress triaxiality. Using AZ31B Mg alloy as the case study material, physical experiments and FE analysis of the rolling process were conducted. The simulations showed that the proposed model can accurately reflect the morphology and location of cracks during the rolling process, and revealed that the high-stress triaxiality at the Mg alloy edge was a significant cause of edge cracking. On this basis, an edge-constraint rolling process was proposed to inhibit edge cracking by embedding the billet into a U-shaped sheet. The numerical results showed that the minimum value of edge stress triaxiality could be reduced from -0.8 to -2.05 during edge-constraint rolling, and the accumulation of damage could be limited. The sheet forming quality was verified with different reduction rates of 30, 35, and 40%, and the results showed that the edge cracks could be effectively avoided during edge-constraint rolling, which provides an important basis for optimizing the rolling deformation process of Mg alloys.

边缘裂纹是一种严重影响轧制镁合金板材质量和性能的损伤。准确的损坏预测在根本原因分析和流程优化中起着关键作用。尽管目前镁合金轧制边缘损伤的唯象预测已经取得了一定进展，但边缘裂纹行为的预测和轧制过程中裂纹形成和演化机制的分析尚未得到很好的报道。在这项研究中，通过修改剪切损伤的增长模式，提出了改进的 Gurson-Tvergarrd-Needleman (GTN) 模型。三维单体有限元（FE）模型试验结果表明，所提出的模型提高了负应力三轴性下断裂响应的准确性。以AZ31B镁合金为案例研究材料，对轧制过程进行了物理实验和有限元分析。仿真结果表明，所提出的模型能够准确反映轧制过程中裂纹的形貌和位置，揭示了镁合金边缘的高应力三轴度是边缘开裂的重要原因。在此基础上，提出了一种边缘约束轧制工艺，通过将坯料嵌入U形板中来抑制边缘裂纹。数值结果表明，边缘约束轧制过程中边缘应力三轴度的最小值可以从-0.8降低到-2.05，并且可以限制损伤的累积。以30%、35%、40%的不同压下率验证了薄板成形质量，结果表明，边约束轧制可有效避免边裂，