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U75V热轧钢轨铺设在曲线地段使用超过3a(年),其中一支钢轨发生断裂,部分钢轨出现剥离掉块。当查找断裂原因,对断裂钢轨进行了理化检验。结果表明:轮轨接触应力过大,超过了钢轨接触疲劳强度,由于疲劳裂纹萌生和扩展的速率大于磨耗速率,在钢轨塑性变形层表面萌生并形成了疲劳裂纹,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。
U75V hot-rolled rail laying in the curved section of the use of more than 3a (years), one of the rail rupture, peel off some rails. When looking for the cause of the fracture, physical and chemical tests were performed on the broken rail. The results show that the wheel-rail contact stress is too large and exceeds the contact fatigue strength of the rail. Since the rate of fatigue crack initiation and propagation is greater than the wear rate, fatigue cracks are formed on the surface of the plastic deformation layer of the rail and fatigue extended along the flow direction , A fatigue nuclear injury was formed 2 mm away from the surface at the contact angle of the wheel and rail and the fracture occurred under the repeated action of the wheel.