Influence of surface treatments on surface layer properties, fatigue and corrosion fatigue performance of AA7075 T73

Ball-burnishing (BB) and shot peening (SP) as surface treatments lead to local plastic deformations in near-surface regions, which result in development of residual stresses and changes in the surface topography. In this study, the effects of various process parameters of shot peening (SP) and ball-burnishing (BB) on the surface layer properties, i.e. surface roughness, microhardness and residual compressive stresses, fatigue and corrosion fatigue properties of Al-alloy AA7075 T73 were investigated. The results show pronounced enhancement in the fatigue life tested in ambient air as well as corrosion fatigue life tested in 3.5% NaCl after both SP and BB compared to the electrolytically polished (EP) reference conditions.

► Ball-burnishing and shot peening change the surface topography and induce compressive stresses.
► The fatigue strength is drastically improved by ball-burnishing and shot peening.
► No significant difference in the fatigue performance by using different shot peening media.
► The corrosive environment markedly reduces the fatigue life.
► Ball-burnishing and shot peening enhance markedly the corrosion fatigue life.