Microstructure evolution and strengthening mechanism of WE43 magnesium alloy subjected to electropulsing-assisted laser shock peening

WE43 magnesium alloy has a hexagonal close-packed (HCP) crystal structure exhibiting poor plasticity and is difficult to process owing to the limited number of slip systems activated at room temperature. Laser shock peening (LSP) has been shown to significantly enhance its mechanical properties, however, excessive laser power may cause surface damage such as cracking. In this study, electropulsing-assisted laser shock peening (ELSP) is investigated for the synergistic effects of laser shockwaves and electron wind to achieve substantial grain refinement at the surface, while significantly enhancing grain growth in deeper regions through the Joule heating effect, and generating deeper compressive residual stress (CRS) and improving the alloy’s overall performance. The results show that ELSP significantly reduces the alloy’s flow stress and increases the depth of the CRS layer to 0.93 mm—a 47.6 % increase as compared to LSP treatment. Furthermore, ELSP not only enhances surface integrity but also promotes dynamic recrystallization, greatly refining the surface microstructure and forming a distinct fine-to-coarse gradient structure, which lead to a 20.6 % increase in tensile strength and a 48.1 % increase in ductility. The study offers a new route for the surface enhancement of high-performance magnesium alloys.