Effect of laser shock peening on electrochemical corrosion resistance of IN718 superalloy

The effects of laser shock peening (LSP) treatment with different impacts on surface roughness, micro-hardness, microstructural observations, residual stress, and electrochemical corrosion resistance of IN718 superalloy were investigated. Results show that the corrosion potential increases to -0.4863 V, -0.2956 V, and -0.3578 V, and the corrosion rate reduces 66.10%, 79.08%, and 84.07% for 2 LSP impacts, 4 LSP impacts, and 6 LSP impacts, respectively, compared with the untreated one. In addition, LSP treatment has an important influence on grain refinement, which increases micro-hardness, reduces roughness of a surface, and also results in a compressive residual stress on a surface, both of which can be responsible for the electrochemical corrosion improvement. Finally, corrosion morphology under scanning electron microscopy demonstrates that LSP is an effective method to prevent the corrosion micro-crack propagation and improve the corrosion resistance. Also, with an increase in laser impacts, the electrochemical corrosion resistance will be further improved. (c) 2018 Optical Society of America