1. School of Mechanical Engineering, Jiangsu University, Zhenjiang, Jiangsu 212013, China; 2. College of Mechanical and Electronic Engineering, Nanjing Forestry University, Nanjing, Jiangsu 210037, China
Abstract：To study the effects of laser peening(LP)on the hot corrosion resistance properties of IN718 superalloy, samples were subjected by high-power LP treatments, and then the corrosion experiments were performed in hot environment of 800 ℃. The compressive residual stress, microstructure, hot corrosion kinetics curves, surface morphologies and cross-section morphologies of the corrosion layers of LPed and non-LPed samples were compared. Finally, the mechanism of hot corrosion resistance strengthened by LP was revealed. The results show that the compressive residual stress is generated and the grains are refined on the surface of LPed sample. While compared with non-LPed sample, the hot corrosion rate of LPed sample is significantly reduced and the number of the corrosion cracks and pits of LPded samples are decreased. The grain refinement speeds up the formation of protective oxide films on the surface of LPed samples, and reduces the thermal stress and growth stress in the oxide films. The compressive residual stress improves the adhesion of the surface oxide films. In addition, the grain refinement and δ phase precipitating on grain boundaries at high temperature hinders the invasion of sulfur, oxygen and other elements, and slows down the internal sulfurization and oxidation rate. As a result, LP can improve the hot corrosion resistance of IN718 superalloy.
