针对线路钢轨出现的一起钢轨母材重伤，采用宏观检验、扫描电镜断口及能谱分析、金相分析、硬度测试等方法对该钢轨母材重伤原因进行了分析。结果表明：钢轨内部的冶金缺陷是其超声波探伤判定为重伤的原因，而该冶金缺陷主要与钢轨铸坯存在裂纹有关；钢轨缺陷部位的高碳马氏体组织与轧制时冷速过快有关，魏氏体组织为轧制时过热所致。建议钢厂加强铸坯的外观检查以及成品钢轨的超声波探伤检查，提高钢轨质量稳定性。

Aiming at the serious damage of rail base metal from a railway site, means such as macroscopic examination, scanning electron microscope (SEM) fracture analysis and energy spectrum analysis, metallographic analysis, hardness testing and so on, were used to investigate the causes for the serious damage of the rail base metal. The results show that the metallurgical defect in the rail was the reason for the serious damage of the ultrasonic flaw detection, and the metallurgical defect was mainly related to the existence of cracks in the rail slab. The high-carbon martensite of the defect position of the rail was related to the rapid cooling speed, and the widmanstatten was due to the overheating when rolling. Steel mills should be recommended to strengthen the appearance inspection of slabs and ultrasonic flaw detection of finished rails to improve rail quality and stability.