Effect of laser shock peening on grain structure, surface hardness, residual stresses, and wear behavior of Al5083 alloy

Abstract The present investigation studies the impact of Laser Shock Peening (LSP) on the microstructural features, hardness, and wear behavior of Al5083 aluminum alloy. The microstructural investigation used an optical and scanning electron microscope (SEM). LSP treatment led to significant grain refinement, reducing the mean grain size from 100 ± 21 to 8 ± 5.5 μm and refining precipitate distribution. The hardness was measured using a Vickers hardness tester. The hardness increased by 15%, reaching 127.5 HV, and remained elevated to 1500 μm depth owing to compressive residual stresses and higher dislocation density. LSP significantly enhances compressive residual stress, with peak values of −312 MPa at the surface and deep penetration up to 1500 μm. Wear testing at different loads (20 N and 40 N) and sliding distances (500 m and 1000 m) using a pin-on-disk tribometer revealed significant enhancement in wear resistance, with the wear rate decreasing by up to 46% and the coefficient of friction reducing by up to 18%. SEM investigation of worn surfaces confirmed reduced delaminations and smoother wear tracks in LSP-treated specimens, showing enhanced surface integrity and wear resistance. Although LSP was carried without a protective coating, surface ablation was minimal, likely owing to optimized process parameters and the material’s high thermal conductivity. The observed hardness distribution demonstrated that the LSP-induced effects extended to approximately 1500 μm depth, after which the hardness returned to the substrate level. The study highlights the effectiveness of LSP in improving the mechanical and wear characteristics of aluminum alloy Al5083, making it an excellent surface treatment for applications requiring improved hardness, wear resistance, and structural reliability in aerospace, marine, and automotive industries.