高碳贝氏体轴承钢滚动接触疲劳性能的研究

Rolling Contact Fatigue Behaviors of High Carbon Bainitic Bearing Steel

以GCr15Si1Mo贝氏体轴承钢为研究对象,在油润滑条件和无润滑条件下,对不同初始碳化物体积分数的试样进行滚动接触疲劳试验,采用扫描电镜观察试验前后试样的表面形貌和碳化物分布,并通过Weibull曲线确定试样滚动接触疲劳性能的优劣性。结果表明,在无润滑条件下,碳化物体积分数为1.9%的试样滚动接触疲劳性能优于碳化物体积分数为5.1%的试样。在油润滑条件下,贝氏体轴承钢的滚动接触疲劳性能的优劣性依次为:无初始碳化物试样、碳化物体积分数为5.1%试样、碳化物体积分数为1.9%试样。碳化物作为基体的硬质相,很容易成为疲劳源,无初始碳化物的贝氏体轴承钢的滚动接触疲劳性能优于有碳化物的贝氏体轴承钢;碳化物脱落后的凹坑增大了润滑油和试样表面的粘着力,有利于增加油膜厚度,从而提高滚动接触疲劳寿命。

Bainitic bearing steel of GCr15 Si1 Mo has been selected as the testing material in this paper. The point rolling contact fatigue experiments are carried out under a well lubricated condition with/without oil lubrication condition. The steel with different volume fractions of carbide are tested. The surface morphology and the distribution of carbides in microstructure of the samples before and after rolling contact fatigue test are observed by scanning electron microscopy. The rolling fatigue properties of these specimens are determined by the Weibull plots. The results show that the rolling fatigue property of the specimen with 1.9 vol.% carbide is superior to the specimen of 5.1 vol.% carbide without lubrication condition. However the order of quality of rolling fatigue property under a well oil lubricated condition of the specimen, from best to the worst is:the specimen without carbide, the specimen with 5.1 vol.% carbide and with 1.9 vol.% carbide. The carbide is easy to be the rolling fatigue crack source as it is a hard phase in matrix of the steel. Then the specimen without carbide shows the best rolling fatigue property. The pits are formed on the surface of the sample after the carbides are fallen off, which increase the adhesive force between the lubricating oil and the surface of specimen. This is beneficial to increasing the oil film thickness during the process of test. Therefore, the rolling contact fatigue life of the specimen is improved.