无碳化物贝氏体钢的滚动接触疲劳磨损行为

Rolling Contact Fatigue Wear Behavior of Carbide-free Bainitic Steel

通过滚动接触疲劳磨损试验和扫描、透射、X射线衍射等分析方法,研究无碳化物贝氏体钢的滚动接触疲劳磨损行为。结果表明,无碳化物贝氏体钢拥有较为理想的滚动接触疲劳磨损性能,其疲劳磨损失效形式为浅层剥落,试样表面产生的严重塑性变形层,有效地阻碍了疲劳裂纹向深处扩展;经过920℃奥氏体化处理40 min,随后350℃盐浴等温30 min比等温100 min处理的试样的滚动接触疲劳磨损性能更加优异,其滚动接触疲劳磨损寿命可达到8.0×10~6次;残余奥氏体能够有效地提高接触表面硬度,松弛裂纹尖端的应力集中,从而改善滚动接触疲劳磨损性能;在滚动接触疲劳磨损过程中,试样表面的硬度显著的提高,表面合金元素的再分配,对滚动接触疲劳磨损性能的提高有一定的促进作用。

Rolling contact fatigue wear(RCFW) behavior of a new type carbide-free bainitic steel(CFBS) has been investigated by means of RCFW testing, scanning electron microscope, transmission electron microscopy and X-ray diffraction. The results show that the CFBS exists the satisfactory RCFW performance, the failure mode of fatigue wear of CFBS is shallow spalling. The severe plastic deformation layer produced on the specimen surface can effectively block the fatigue crack toward greater depth. The RCFW behavior is more excellent of the sample which is austenized at 920 ℃ for 40 min, and immediately austempered in a molten salt bath at a temperature of 350 ℃ for 30 min than that for 100 min. The RCFW life of the sample of 350 ℃ for 30 min can reach 8.0×10~6 cycles. Retained austenite can effectively improve the hardness of the contact surface and relax the stress concentration at the crack tip, and the RCFW behavior is improved. During the RCFW process, the hardness increase in the specimen surface and redistribution of the alloying elements exhibit a positive effect on the improvement of the RCFW behavior.