Effect of Cryogenic Treatment on the Friction and Wear Properties of GCr15 Bearing Steel      

The effects of different cryogenic treatment durations on the microstructure and properties of GCr15 bearing steel were investigated through performance testing, friction and wear tests, X-ray diffraction (XRD), and scanning electron microscope (SEM). The results indicate that after cryogenic treatment, the content of fine carbides increases and they are more uniformly dispersed, while the amount of retained austenite is reduced. Compared to the non-cryogenically treated sample, the retained austenite content decreases by 27 % and 39.20 % after 6 h and 72 h of cryogenic treatment, respectively. Consequently, the hardness and wear resistance of GCr15 bearing steel are enhanced following cryogenic treatment, and prolonging the cryogenic duration is beneficial for further improving its performance. When the cryogenic time is extended from 6 h to 72 h, the hardness increases from 684.60 HV1.0 to 690.80 HV1.0 and then to 701.20 HV1.0; the wear rate decreases from 5.87×10^-6 mm³/(N·m) to 4.45×10^-6 mm³/(N·m)and then to 2.95×10^-6 mm³/(N·m), respectively. Compared with the non‑cryogenically treated D0 sample, the wear rate of the D2 sample (cryogenically treated for 72 h) was reduced by 49.70 %, exhibiting the optimal wear resistance.