Study on Surface Integrity and Electrochemical Corrosion Resistance of Laser Shock Peened Zr-4 Alloy Based on Orthogonal Test

Zr-4 alloy is widely used as a structural material in nuclear reactors due to its good corrosion resistance. In the service process, it is exposed to high radiation, high temperature and high-pressure environments for a long period of time, resulting in the degradation of surface properties. Laser Shock Peening (LSP) technology can effectively improve the surface integrity and corrosion resistance of materials. In this study, the orthogonal test design method was used to investigate the effects of different LSP parameters on the surface properties of Zr-4 alloy using laser energy (Le), spot diameter (Sd), pulse overlap rate (Po) and scanning times (St) as the main research factors. Results show that the surface morphology of Zr-4 alloy after LSP has pits and a molten layer formation, resulting in increased roughness. Surface hardness, residual compressive stress and contact angle increase after LSP treatment compared to those of the Zr-4 alloy matrix. The results of the range analysis show that Sd is the main factor affecting the surface roughness and hardness of Zr-4 alloy. Po has the greatest impact on the contact angle. The influence of Le on the residual compressive stress and electrochemical corrosion resistance is most significant. Changes in electrochemical corrosion resistance are closely related to their surface integrity properties (surface roughness, contact angle, microcracks and residual compressive stress).