Cavitation erosion behaviour of AISI 420 stainless steel subjected to laser shock peening as a function of the coverage layer in distilled water and water-particle solutions

Abstract Influences of the coverage layer on cavitation erosion (CE) behaviour, cavitation-silt erosion (CSE) behaviour and damage morphologies of AISI 420 steel subjected to massive laser shock peening treatment (MLSPT) was studied through mass loss measurement, scanning electron microscopy observation, microstructure characterization, and residual stress measurement. Results showed that original martensitic laths with an average width of 450 nm were refined into fine equiaxed grains of 94-220 nm under the mechanical effect of ultra-strong laser shock wave. Moreover, MLSPT induced a compressive residual stress layer up to 1 mm deep, and the surface residual stress was up to -400 MPa. In addition, the average cumulative mass losses of LSPed specimens were respectively 42.2% and 26.5% lower than that of the non-treated specimen in distilled water and water-particle solution, and the erosion resistance was significantly improved with increasing the coverage layer due to the MLSPT-induced grain refinement and compressive residual stresses in the surface layer.