Effect of laser energy density on surface physical characteristics and corrosion resistance of 7075 aluminum alloy in laser cleaning

In this paper, the pulsed laser cleaning technology was used to remove the oxide film on the surface of 7075 aluminum alloy. The effects of different laser energy density on the surface morphology, surface composition, microhardness and corrosion resistance of 7075 aluminum alloy were analyzed. The removal mechanism of oxide film on 7075 aluminum alloy surface by laser cleaning was studied. The results show that laser cleaning 7075 aluminum alloy oxide film is mainly based on gasification mechanism and shock wave generated by explosion. After laser cleaning, the surface microhardness of 7075 aluminum alloy increases from 158.5HV to 171.9HV. After removing the oxide film on the surface of aluminum alloy by laser, the corrosion resistance of the surface decreases, and surface melting also affect the corrosion resistance of the cleaned surface. In this study, when the energy density is in the range of 1.43 J/cm2 to 1.82 J/cm2, the oxide film can be largely removed without damaging the substrate. At the same time, the corrosion resistance of the surface is ensured as much as possible. When the energy density reaches 1.82 J/cm2 in this research, the mass percentage of oxygen on the cleaned surface is reduced to 2.03%, and the microhardness is 167.7HV.