Impact of laser shock peening on the microstructure and mechanical performance of 7075 aluminum alloy

7075 aluminum alloy is extensively utilized in high-end manufacturing sectors such as aerospace, owing to its outstanding mechanical properties. However, the 7075 aluminum alloy typically experiences multiple complex working conditions during its service. Enhancing its performance is crucial for improving the service reliability of the entire structure. This study explores the effects of laser shock peening (LSP) on the microstructure and mechanical properties of 7075 aluminum alloy. The results demonstrate that LSP significantly improves microhardness, tensile strength, and strain-hardening behavior, while promoting grain refinement and increasing dislocation density. With an increasing number of LSP cycles, dislocation density rises, leading to the formation of fine-grained surface layer. After LSP for 4 cycles, the surface microhardness increased to 205.8 HV, reflecting a rise of 21.73%. The yield strength and ultimate tensile strength were measured at 510.06 MPa and 572.11 MPa, respectively, indicating increases of 9.62% and 5.40%. Furthermore, LSP-treated specimens exhibited higher strain-hardening rate compared to the untreated alloy, indicating enhanced strengthening. However, elongation decreased with the increase in LSP cycles, likely due to the elevated dislocation density and the consequent reduction in plastic deformation capacity. Overall, LSP emerges as a promising surface treatment technique for enhancing the mechanical properties of 7075 aluminum alloy, with potential applications in industries demanding high-strength materials.