列车车轮滚动接触疲劳裂纹评价研究

列车车轮踏面表层金属滚动接触疲劳是影响列车运行安全性和舒适性的核心科学问题. 借助金相显微镜、扫描电镜、透射电镜和显微硬度计，通过开展列车车轮材料的标准滚动接触疲劳试验，将标准接触疲劳样品的损伤行为与实际服役车轮的损伤行为对比分析，研究了列车车轮的滚动接触疲劳裂纹评价方法. 结果表明:车轮表层金属接触疲劳开裂是表层金属累积塑性变形损伤的结果；标准滚动接触疲劳样品剥离坑的深度恰好等于硬化层的深度，实际服役车轮剥离坑的深度小于硬化层的深度；将车轮表面的滚动接触疲劳裂纹命名为“三角形指向性裂纹”；初步建立了车轮表面滚动接触疲劳损伤程度的定量评价方法. 

Evaluation of Rolling Contact Fatigue Crack of Train Wheels

Rolling contact fatigue of the wheel tread, which affects the safety and comfort of train, is the key scientific issue. Standard rolling contact fatigue test was carried out for a common wheel material and the damage behaviors of the standard rolling contact fatigue sample and the service wheel were compared using metallographic microscope, scanning electron microscope, transmission electron microscope and microhardness tester. The rolling contact fatigue crack evaluation method of the train wheel were studied. The results show that the rolling contact fatigue cracking is the result of cumulative plastic deformation damage of the surface metal. The depth of the spalling pit of the standard rolling contact fatigue sample is exactly equal to the depth of the hardened layer. The depth of the spalling pit of the service wheel is less than the depth of the hardening layer. The rolling contact fatigue crack on the wheel surface is designated as “triangular directional crack. Quantitative evaluation method for rolling contact fatigue damage degree of wheel surface was proposed.