Wear Resistance of 20CrMo Carburized Steel after Boriding and Sulfur Nitrogen Boriding Treatment

Using ferroboron and B₄C as a boron source respectively and adding moderate nitrogen source, sulphur source and fillers, the boriding layers and sulfur nitrogen boriding layers on the surface of 20CrMo carburized steel were prepared by the powder embedding method, and then the phase composition, hardness and wear resistance of the two layers were analyzed. The results show that the boriding layers were both composed of Fe₂B, FeB and Fe₃C phases while the sulfur nitrogen boriding layers were composed of Fe₂B, Fe₃N, FeS and Fe₃C phases without the formation of brittle FeB phase. The surface hardness, abrasive and adhesive wear resistance of the boriding layers and the sulfur nitrogen boriding layers were all higher than those of the carburizing layer. Moreover, the surface hardness and abrasive wear resistance of the boriding layers were higher while the adhesive wear resistance was lower than those of the sulfur nitrogen boriding layers. The abrasive wear resistance of the boriding layers prepared with ferroboron as a boron source was higher while the adhesive wear resistance was lower than those with B₄C as a boron source.