Analysis of Fatigue Life and Surface Roughness in Laser Peened Al6082/SiC/7.5% Metal Matrix Composite

Objectives: To investigate the influence of laser shock peening (LSP) energy on fatigue life and surface roughness of stir-cast Al6082/SiC/7.5% metal matrix composites. Methodology: Al6082/SiC/7.5% composites were fabricated using stir casting and subjected to laser shock peening at energy levels of 1 J, 2 J, and 2.5 J using a Q-switched Nd:YAG laser. Rotating bending fatigue tests were conducted to determine fatigue life, while surface roughness was measured using a contact profilometer. Findings: Fatigue life increased by 29%, 34.77%, and 44.5% at 1 J, 2 J, and 2.5 J respectively compared to un-peened composites. Surface roughness decreased by 1.40% at 2 J and 6.50% at 2.5 J, indicating improved surface integrity at higher laser energies. Novelty: This study establishes a quantitative relationship between laser shock peening energy, fatigue enhancement, and surface roughness reduction in Al6082/SiC composites, identifying an optimal processing window that has not been clearly reported for particle-reinforced aluminum metal matrix composites. Keywords: Al6082 MMC, SiC reinforcement, Laser peening, Fatigue life, Surface roughness