Effect of shot peening on surface characterization and cavitation resistance of nickel aluminum bronze

Abstract

Nickel aluminum bronze is subjected to cavitation corrosion as propellers working in the seawater. The cavitation corrosion is dominated by the synergistic effect of corrosion and mechanical attack. Previous studies have demonstrated that shot peening (SP) could enhance surface mechanical strength through residual stress and refined grains. In this work, shot peening with Almen intensities from 30 A to 40 A is performed on the nickel aluminum bronze to investigate the effect on the corrosion and cavitation performance. After shot peening with the rough surface, the samples exhibit higher corrosion current densities due to the increased corrosion area and galvanic cells compared to the as-treated samples. Meanwhile, the samples treated by 40 A show the lowest mass loss during the cavitation test and the highest surface micro-hardness. The enhancement of the cavitation resistance is dominated by the coupling mechanism of the surface corrosion aggravation and strain strengthening. Meanwhile, the higher current intensity, the more pronounced surface strengthening enhancement due to the grain refinement's synergistic mechanism and dislocation density.