Improvement in cavitation erosion resistance of AA5083 aluminium alloy by laser shock processing

Abstract

Aluminium alloys are commonly used to manufacture the components that service under cavitation erosion environment. However, their poor cavitation erosion performance results in a significant reduction in their service life. In this study, a novel surface treatment method for improving cavitation erosion resistance by laser shock processing (i.e. laser shock peening with ablative coating (LSP) and laser shock peening without ablative coating (LSPwC)) was proposed. The microstructure, microhardness and residual stress of AA5083 aluminium alloy after laser shock processing were investigated. The cavitation erosion experiments were performed by ultrasonic cavitation. The cumulative mass loss, maximum surface damage depth, surface roughness and eroded surface morphologies during the cavitation erosion tests were characterized. The results indicate that laser shock processing can lengthen the incubation period and decrease the mass loss. The cavitation erosion resistance of LSP and LSPwC specimens is about 1.45 and 2.13 times that of substrate after 300 min cavitation erosion test, respectively. The eroded surface of substrate shows more serious damage morphology than that of treated specimens. The enhancement of cavitation erosion resistance for treated AA5083 aluminium alloy is ascribed to the refined grain and surface compressive residual stress, which can hinder the crack initiation and propagation, thereby inhibiting material spalling during cavitation erosion.