Sliding wear behavior of nitrocarburized bearing steel

Four-ball tribological apparatus was employed to investigate the sliding we ar behavior of bearing steel 52100 treated by salt bath nitrocarburizing an d complex nitrocarburizing processes. The microstructures, phase identifica tion, surface hardness and hardness profiles of specimens were analyzed by optical microscopy, X-ray diffraction and microhardness testing. The experi mental results show that higher sub-surface hardness and hardness profiles were obtained by nitrocarburizing and complex nitrocarburizing, although th eir surface hardness was lower than that of commercial balls. It was also d emonstrated that the E-phase formed on the specimen surfaces had a signific ant effect on reducing friction coefficient but this treatment lowered the wear resistance. Complex nitrocarburizing increased the wear resistance. Bo th Nitrocarburizing and complex nitrocarburizing could upgrade the load-bea ring capacity of treated specimens. (C) 2000 Elsevier Science S.A. All righ t reserved.