Effects of Primary Carbide Size and Type on the Sliding Wear and Rolling Contact Fatigue Properties of M50 Bearing Steel

The influences of primary carbide size and type on the sliding wear behavior and rolling contact fatigue (RCF) properties of M50 bearing steel were systematically investigated under oil lubrication condition. A major breakthrough was achieved in the influence of primary carbide on tribological behavior. The opposite effect brought by primary carbide size on the sliding wear resistance and RCF life of M50 bearing steel was determined. Wear resistance increased with an increase in the studied primary carbide size, whereas RCF life decreased significantly. Compared with the 0 R and R positions with a relatively small carbide size, the wear volume of the 1/2 R position with a large carbide size was the smallest. Compared with the 0 R and R positions, the L10 life of the 1/2 R position decreased by 82.7% and 84.8%, respectively. On the basis of the statistical correlation between primary carbide size and the two tribological properties, a critical maximum carbide size of 5–10 μm was proposed to achieve optimal tribological performance. This research suggests that the equivalent diameter of the primary carbide should be controlled to be smaller than 10 μm, but further decreasing primary carbide size to less than 5 μm is unnecessary. The influence of primary carbide type in M50 bearing steel on sliding wear resistance was also discussed. Results indicate that the MC-type carbides with higher elastic modulus and microhardness exhibit better wear resistance than the M2C-type carbides.

本研究在油润滑条件下，系统探究了初生碳化物的尺寸与类型对M50轴承钢滑动磨损行为及滚动接触疲劳（RCF）性能的影响，并在初生碳化物对摩擦学行为的影响方向取得了重要突破。经研究明确，初生碳化物尺寸对M50轴承钢的滑动耐磨性能与滚动接触疲劳寿命存在相反作用效果：随着所考察的初生碳化物尺寸增大，材料的滑动耐磨性能逐步提升，而滚动接触疲劳寿命则显著下降。相较于碳化物尺寸相对较小的0R与R位置，碳化物尺寸更大的1/2R位置磨损体积最小；相较于0R与R位置，1/2R位置的L10寿命分别降低82.7%与84.8%。基于初生碳化物尺寸与上述两项摩擦学性能的统计相关性，本研究提出可实现最优摩擦学性能的临界最大碳化物尺寸区间为5~10 μm，建议将初生碳化物的等效直径控制在10 μm以下，且无需将其进一步缩减至5 μm以下。此外，本研究还探讨了M50轴承钢中初生碳化物类型对滑动耐磨性能的影响，结果显示，弹性模量与显微硬度更高的MC型碳化物，其耐磨性能优于M2C型碳化物。