Fittability and mechanical properties of laser shock liquid warm microforming of AZ31B magnesium alloy foils with complex features

Abstract

Difficult-to-form materials and complex mold characteristics have an important effect on the fittability and mechanical properties of microforming components. This study focuses on the fittability and mechanical properties of laser shock liquid warm microforming based on AZ31B magnesium alloy foils and a complex microcamera shell die. The characteristics of formed parts under varying temperatures and laser energies were discussed. Single-pulse and double-pulse forming experiments were conducted and compared. At 140 °C and 1260 mJ, double-pulse forming achieved a maximum depth of 184.5 μm, demonstrating near-perfect workpiece conformity to the die. In contrast, single-pulse forming did not achieve such results. This implies that double-pulse forming notably improves the fittability of workpieces and effectively mitigates springback. Finite element simulations corroborate the experimental findings. Moreover, simulation elucidates phenomena observed during experiments, including springback and crack formation. Additionally, the study delves into the microhardness, thickness distribution, and surface roughness of the formed parts. The results indicate that double-pulse forming yields workpieces with superior microhardness, reduced roughness, and a more uniform thickness distribution. Microstructural analysis reveals that grain refinement and substantial occurrence of twinning in the double-pulse forming process are the primary factors contributing to enhanced plasticity. The study also conducts a failure analysis of formed parts at room temperature, revealing the presence of numerous river patterns and cleavage planes, indicative of brittle fracture. Conversely, warm forming avoids fracture failure.