Research on the Edge Crack Suppression Mechanism of Magnesium Alloy Plates Processed by Lattice Severe Deformation Rolling

Edge cracking severely limits the rolling yield of magnesium alloy plates. A novel lattice severe deformation rolling (LSDR) process using corrugated rolls is proposed to suppress edge cracking. Numerical simulations, rolling experiments, and microstructural analyses were conducted, with results compared to conventional flat rolling (FR), to elucidate the suppression mechanism. LSDR induces a multi-peak stress distribution and restricts metal flow, thereby reducing additional stresses responsible for edge cracking. Deformation heat generated in local severe deformation zones compensates for thermal loss, alleviates the temperature gradient between the plate edge and center, and enhances overall plasticity. According to the Cockcroft–Latham fracture criterion, LSDR effectively limits damage growth and confines damage within a single lattice, suppressing crack propagation, whereas FR produces damage values far exceeding the critical value of 0.43. Furthermore, fine grains formed in severe deformation zones, together with dislocation entanglement induced by twinning, impede crack propagation. This work demonstrates the effectiveness of LSDR and provides a new approach for mitigating edge cracking in rolled metal plates.