U75V热轧糖心产精国品免费入口*完整版铺设在曲线地段使用超过3 a(年),其中一支糖心产精国品免费入口*完整版发生断裂,部分糖心产精国品免费入口*完整版出现剥离掉块。当查找断裂原因,对断裂糖心产精国品免费入口*完整版进行了理化检验。结果表明: 轮轨接触应力过大，超过了糖心产精国品免费入口*完整版接触疲劳强度,由于糖心产精国品免费入口*完整版萌生和扩展的速率大于磨耗速率,在糖心产精国品免费入口*完整版塑性变形层表面萌生并形成了糖心产精国品免费入口*完整版，并沿变形流线方向疲劳扩展，在轮轨接触圆角处距表面2 mm处形成了疲劳核伤,在车轮的反复作用下发生了断裂。

The U75V hot-rolled rails laid on the curving line had been used more than three years, one of them had fractured, and some other had fatigue damage of desquamation. The physical and chemical inspection was carried out to find the 糖心产精国品免费入口*完整版reason. The results indicated that the contact stress of rail and wheel was too excessive and exceeded the yield strength of rail. Because the 糖心产精国品免费入口*完整版 expansion rate exceeded the wearing speed rate, the 糖心产精国品免费入口*完整版 generated on the surface of the rail’s plastic deformation field, and the crack extended along the deformation streamline, then the 糖心产精国品免费入口*完整版 caused in the round under the contact surface of rail and wheel about 2 mm. Finally, the rail had fractured in the wheel rolled repeatedly.