Effect of Original Microstructure on Contact Fatigue Property of CL70 Wheel Steel

The wear test and rolling contact fatigue test of CL70 wheel steel specimens with the original structure of lamellar pearlite+proeutectoid ferrite (P+F) and tempered sorbite (TS) were carried out using double-disk rolling contact fatigue tester.The optical microscope, scanning electron microscope and hardness tester was used to analyze the structure and hardness. The influences of original structure on the fatigue performance were studied. The results show that:P+F specimen and TS specimen have different wear mechanisms on the surface after pre-wearing. The surface of P+F specimen is mainly fatigue wear, and accompanied by peeling phenomenon.The surface of the TS specimen is mainly adhesive wear and abrasive wear, with slight fatigue wear; the surface layers of the two original structures are fine ferrite matrixes with fine cementite, but the surface grains of the P+F specimen are smaller, the hardness is higher, and the thickness of the deformation layer is also thin.The contact fatigue test results of the two pre-wear specimens show that the fatigue life of the TS specimen is 4.4 times higher than that of the P+F specimen.The surface morphology of the fatigue specimens are that after fatigue, the TS specimen mainly has typical fatigue spalling deep pits on the surface, while the P+F specimen mainly has pitting flaking on the surface accompanied by spalling deep pits.Pre-wear can refine the structure and increase the hardness, while reduce the fatigue wear, which help improve the fatigue life.