Effect of Compound Treatment of Laser Shock Peening and Nitriding on Wear Resistance of M50 Steel

The surface modification of M50 steel was carried out by the compound treatment of laser shock peening and plasma nitriding, and the effects on the microstructure, hardness and wear resistance of the steel were studied. Results show that after single nitriding treatment, much vein microstructure was formed in the nitrogen atom diffusion zone near the surface, but there was less vein microstructure in the nitrided layer of the steel after compound treatment (LSP + PN). This is related to the fact that LSP caused many dislocations on the surface of the steel, which increased the diffusion channels and rate of nitrogen atoms. After wear test, compared with the substrate, the wear loss of the specimen after single nitriding and compound treatment was reduced by 23.81% and 75.71%, and the friction coefficient was reduced by 9.76% and 13.41%, respectively. The compound treatment significantly improved the wear resistance of M50 steel.