Study on wear resistance of 38CrMoAl steel with nitridation enhanced by laser shock wave

To improve the quality of nitriding layer and wear resistance of 38CrMoAl-steel, a new method was put forward by which the sample was treated by laser shock processing before nitriding. The wear resistances of different samples with nitriding and nitriding after laser shock processing were tested by the ball milling experiment, and their microstructures were analyzed by XRD and SEM. The enhancement mechanism of wear resistance by laser shock processing before nitriding was also discussed. The wear rate of the sample with laser shock processing was 9.47×10^-15 m³/Nm, reducing about 50% compared to the samples with nitriding only, and the surface micro hardness was increased by 12%. The grains in the surface layer were refined by laser shock wave, and there were many high density dislocations. The grain refinements and the high density dislocations near the surface provided more channels for the nitrogen diffusion process. More nitrogen infiltrated into the α-Fe matrix metal, resulting in solution strengthening. On the other hand, the microstructure of the nitriding layer was dense, and defect-free, with a large number of nitrides distributed along the grain boundary.