采用宏观及微观断口分析、化学成分分析、硬度测试及金相检验等方法, 对某贝氏体钢轨在矫直时发生断裂的原因进行了分析。结果表明: 造成该贝氏体钢轨矫直断裂的主要原因是其显微组织中存在大量的针状马氏体晶间脆性组织, 当钢轨受到矫直外力作用时, 便从马氏体脆性相应力集中部位的夹杂物处开始起裂, 裂纹沿脆性晶界迅速扩展最终导致断裂。

Means such as macro and micro fracture analysis, chemical compositions analysis, hardness test and metallographic examination were used to analyze the fracture reasons of bainite steel rails which fractured when straightening. The results show that the main reason for the fracture was attributed to intercrystalline brittleness of a great deal of acicular martensite in the microstructure of the bainite steel rails. When the rail received straightening stress, cracks initiated from inclusions at the intercrystalline brittleness phase stress concentration positions, and the cracks expanded rapidly along the brittle grain boundaries and led to fracture eventually.