目的 探究高合金表面硬化轴承钢的滚动接触疲劳失效机理，以提高钢的疲劳寿命。方法 在球棒滚动接触疲劳试验机上进行滚动接触疲劳试验，测试试验钢的疲劳寿命，其中，滚动体为GCr15钢，钢棒为高合金表面硬化轴承钢。采用显微硬度仪、光学显微镜、扫描电子显微镜和Thermo-Calc热力学计算软件等，分析了失效钢棒的渗碳层深度、碳化物类型、碳化物分布，研究钢棒表面磨损行为和滚动接触疲劳的失效类型、裂纹起裂原因、裂纹扩展机理。结果 试验钢棒经表面渗碳处理后，渗碳层深度达到1.6 mm，表面硬度最高为827HV。渗碳层碳化物为M23C6、M7C3、M6C，其中，M23C6主要分布在渗碳层晶界上，M7C3和M6C主要分布在晶体内部。试验钢棒在5 GPa接触应力下循环1.02×10⁹周次后，其滚道深度为9.3 μm，压入量为0.093%。球棒润滑状态为部分膜弹流润滑，随着疲劳周次的增加，表面磨损加剧，磨损类型为疲劳磨损。循环2.76×10⁸周次后，钢棒发生剥落失效，失效类型为渗碳层碳化物引起的表面起裂失效和次表面剪切应力引起的次表面起裂失效。在剥落坑下部，发现白蚀区(white etching area, WEA)，WEA的硬度为684HV，比基体的硬度升高了25.4%。在WEA内，与滚动方向呈一定角度的小裂纹汇聚形成主裂纹，主裂纹穿过渗碳层，终止于距表面1.5 mm处。在距表面560 μm处，发现宽度为610 μm的黑蚀区(dark etching regions, DER)，DER的硬度为612HV，比基体的硬度降低了10.5%。结论 控制渗碳层的碳化物尺寸和形状，可以进一步提高高合金表面硬化轴承钢滚动接触疲劳寿命。

Rolling contact fatigue is the most important failure mode of bearings. The failure mechanism of rolling contact fatigue of high-alloy case-hardened bearing steels is studied to provide the basis for improving the service life of bearing steels. The test was carried out on the rolling contact fatigue (RCF) test rig to test the fatigue life of the experimental steel. The rolling element is GCr15 steel and the steel rod is high-alloy case-hardened bearing steel. By means of a microhardness tester, optical microscope, scanning electron microscope and thermodynamic calculation software, the depth of carburized case and carbide type and distribution were observed, and the surface wear behavior, rolling contact fatigue failure type, reason of crack initiation and crack propagation mechanism of the failed steel were analyzed. The results show that the depth of carburized case is 1.6 mm, and the maximum surface hardness is 827HV after surface carburizing. The carbides of carburized case are M23C6, M7C3 and M6C. M23C6 is mainly distributed in grain boundary carburized case, while M7C3 and M6C are mainly distributed in grains. After 1.02×109 cycles under a contact stress of 5 GPa, the raceway depth is 9.3 μm and the amount of indentation is 0.093%. The lubrication state between the ball and the rod is partial elastohydrodynamic lubrication. With the increase of fatigue cycles, the surface wear becomes more severe, and the wear type is fatigue wear. When the fatigue life reached 2.76×108, spalling failure occur in the experimental steel. The failure types are the surface cracking failure caused by carburized carbides and the subsurface cracking failure caused by subsurface shear stress. A white etching area (WEA) is found in the lower part of the spalling pit. The hardness of WEA is 684HV, 25.4% higher than that of base. The white etching area is composed of many small cracks that converged to form a main crack, which passes through the carburized case and ends at 1.5 mm away from the surface. A 610 μm wide dark etching regions (DER) is found at 560 μm away from the surface. The hardness of DER is 612HV, 10.5% lower than that of the base. The rolling contact fatigue life of high-alloy case-hardened bearing steel can be effectively improved by controlling the size and shape of carbides in the carburized case.