针对U71Mn钢轨在矫直过程中出现断裂的现象，对钢轨断口部位的宏观形貌、显微组织、化学成分、力学性能和显微硬度等进行了观察和分析。结果表明:钢轨角部的外来夹杂物、网状渗碳体、针状渗碳体魏氏组织，以及钢轨角部由于擦伤出现的隐针马氏体和微裂纹，是造成钢轨矫直断裂的主要原因。最后探讨了解决措施。

In order to solve the problem of U71Mn steel rails fracture during straightening, microstructure, chemical compositions, mechanical properties and microhardness of fracture positions were observed and studied, respectively. The results show that the foreign inclusions, network cementite, acicular Widmanstatten cementite, the fine acicular martensite and micro cracks in corner of the steel rail because of friction impairment were main reasons for fracture of the U71Mn steel rails during straightening. At the same time, the solving measures were discussed.