Effect of laser shock peening on the surface integrity and wear performance of carburized and quenched gear steel

To explore the effects of Laser Shock Peening (LSP) processing on the surface integrity and wear performance of carburized and quenched gear steel, laser energy, and spot diameter were selected as variable parameters, and five laser power density processing parameters were constructed to perform LSP on carburized and quenched 18CrNiMo7-6 gear steel. Surface roughness, surface hardness, hardness gradient, and residual stress were tested, and the tooth surface wear rate before and after LSP was compared through theoretical calculations. LSP has less impact on surface roughness. Laser power density is within 9.4 GW·cm −2 ~10.2 GW·cm −2 , and LSP can slightly reduce the surface roughness value. LSP can improve the surface hardness and cross-section hardness within a certain depth, and the improvement effect increases with the increase of laser power density. The residual compressive stress value with the increase of laser power density shows a trend of decrease after the first increase and reaches the maximum value at the laser power density of 9.4 GW/cm −2 . Adopting a suitable LSP processing can improve the wear resistance of gear tooth surfaces. The wear rate of the gear tooth surface at the engage-in position has decreased to the largest, and the decrease is about 18%.