某异型钢轨在经60kg/m热轧钢轨加工至50kg/m过渡轨后出现矫直断裂。经对钢轨断口的宏、微观检验和分析，认为，断裂裂纹起源于轨腰次表层；钢轨发生矫直断裂的原因是在加工异型钢轨的过程中，加热温度偏高，导致轨腰表层部分区域出现沿晶氧化，锻压时因轨腰表层受拉应力作用，沿晶氧化处形成微裂纹，随后矫直时轨腰三点弯曲受力，微裂纹缺陷处产生应力集中致使裂纹扩展，导致钢轨断裂。

In a factory, a fracture occurred in a transition rail of the 60kg/m to 50kg/m in the correction.Macro and microstructure inspections and compostion analysis of the fracture rail showed that surface layer of the rail waist there is primitive small cracks, it was grown by the 3-point curve correction lead to the rail fracture. The reason of the primitive small cracks is too high heating temperature and cause the serface layer of the rail waist result from grain bounderies oxidation, and by forging and pressing lead to crack in the position that was oxidized.