Application of GTN Damage Model Based on Hill’48 Anisotropic Yield Criterion in Forming of ZK60 Magnesium Alloy Sheets

Sheet cracking severely impacts the formability of magnesium alloy sheets during rolling, representing a critical defect that cannot be overlooked. Accurate analysis of plastic anisotropy is essential to reveal the mechanisms behind edge cracking. To predict damage evolution during room‐temperature rolling, this study employs a shear‐modified anisotropic Gurson–Tvergaard–Needleman (GTN) model, incorporating Zhou's modified GTN model for low stress triaxiality and Hill’48 anisotropic yield criterion, to investigate transverse through‐thickness cracks (45° to rolling direction [RD]) under 30% reduction. Using ZK60 magnesium alloy as the research material, mechanical tests with digital image correlation are conducted, and the shear‐modified GTN model is integrated into ABAQUS/Explicit via a VUMAT subroutine to calibrate rolling parameters. The results demonstrate that the model accurately predicts the location and morphology of rolling cracks and reveals that ZK60 exhibits significantly lower yield strength in the transverse direction than in the RD, making it more susceptible to shear band initiation under transverse tensile stress. Low stress triaxiality () promotes shear damage, causing microvoid coalescence along 45° to form cracks, while high stress triaxiality () leads to microvoid expansion. Ultimately, surface shear cracks preferentially propagate through the thickness, forming macroscopic cracks at 45°.