Effect of laser shock peening and heat treatment on the electrochemical behavior of IN718 superalloy

Abstract

The IN718 superalloy underwent laser shock peening (LSP) and heat treatment (HT) processes. The electrochemical corrosion behavior of four sample types was evaluated in a 3.5 wt% NaCl water solution. The results indicated that the combined application of LSP and HT (LSP + HT) significantly improved the corrosion resistance of IN718. LSP refined grain size and modified dislocation structure, creating additional diffusion channels and increasing binding energy. These changes promoted the precipitation of higher quantities of γ′ and γ″ phase particles during subsequent HT, accelerating the formation of a protective passivation layer. The HT process concurrently minimized microscopic defects within the crystal structure, significantly enhancing the material's corrosion resistance. Moreover, the corrosion current density of the LSP + HT samples decreased by 76.26 % compared to the as-received (AR) samples. Additionally, surface pitting in the LSP + HT samples was substantially reduced after corrosion, with the average pit diameter decreasing by 53.7 % compared to the AR samples.