Reesidual Stress and Performance of 18Cr2Ni4WA Steel after Nitriding and Shot Peening Treatment

Shot peening and nitriding-shot peening surface treatments were applied to worm and worm gear samples with material of 18Cr2Ni4WA steel which requires high surface properties. The residual stress distribution and micro-hardness distribution were analyzed after these two different surface treatments. The results show that only with shot peening the maximum surface residual stress was -484 MPa and the maximum hardness was 735 HV, but after nitriding-shot peening the maximum surface residual stress reached -1214 MPa and the maximum hardness reached 1113 HV. Both these two surface treatment methods could greatly improve the residual stress and hardness of the material surface, and the effect of nitriding-shot peening method was better.