U75V热轧钢轨铺设在曲线半径R=400 m地段使用2 a(年)多, 部分钢轨出现了严重的接触疲劳裂纹及剥离掉块伤损, 采用化学成分分析、扫描电镜以及能谱仪分析、光学显微镜分析等方法对钢轨伤损原因进行了分析。结果表明: 钢轨出现剥离掉块和接触疲劳裂纹伤损的主要原因是轮轨接触圆角处的接触应力过大超过其接触疲劳强度, 在钢轨塑性变形层表面萌生疲劳裂纹并沿变形流线方向疲劳扩展, 在轮轨接触圆角处形成疲劳核伤;可通过提高冶金质量、铺设高强度等级的钢轨、改善轮轨接触关系及受力状态、对出现接触疲劳裂纹的钢轨进行打磨等措施来延长钢轨的使用寿命。

Parts of U75V hot-rolled steel rails which were laid in the line with the curve radius R=400 m appeared contact fatigue cracking and peeling after two years, and the damage reasons were analyzed by means of chemical compositions analysis, scanning electron microscope and energy dispersive spectrometer analysis and metallographic examination. The results indicate that the main reason for the contact fatigue cracking and peeling damage was that the contact stress of the contact round corner of the rail and wheel was too large and exceeded its fatigue strength, which resulted the fatigue cracks initiated in the rail’s plastic deformation layer and propagated along the deforming line, and finally caused crosswise fatigue damage on the contact round corner of rail and wheel. Measures such as improving the metallurgical quality, laying high strength rails, improving the contacting condition of the rail and wheel to change the stress state and polishing the rails with contact fatigue cracks could be adopted to extend the service life of the rails.