The Effect of Shot Peening on Surface Layer Properties and Corrosion Fatigue Behavior of 7075-T6 Aluminum Alloy in Sea Water

Shot peening as a surface treatment is a process that by bombardment of shots on the metal surface, creates plastic deformation and compressive residual stresses beneath the surface. On the other hand, aluminum alloys for having high strength against weight ratio and good corrosion resistance, as compared to other metals, is utilized in sea industries. The present paper investigates the effect of shot peening on the surface layers properties such as surface roughness, surface layers hardness, and the effect of formed compressive residual stresses on behavior of corrosion fatigue of 7075-T6 aluminum alloy in sea environment. For this purpose, surface of the aluminum specimens were prepared under the tossed balls and plastic deformation on the surface was created. The residual stresses in the subsurface layers were formed. Roughness and hardness of the surface layer was measured by micro hardness and roughness tester machine. The polished and shot peening specimens under the rotating fatigue corrosion are tested. The obtained results by the research show the increase of surface layers hardness, surface roughness, corrosion fatigue life time, and strength of the alloy by shot clashes and compressive residual stresses resulting from shot peening process compared to polishing specimens.