利用扫描电子显微镜、光学显微镜、直读光谱仪、拉伸试验机等对某伤损钢轨轨头的断口形貌、显微组织、化学成分、拉伸性能等进行了测试，探讨了纵横裂型核伤的形成原因并提出了解决措施。结果表明：在循环工作应力的作用下，在钢轨轨头轮轨接触应力分布区内沿轧制方向分布的粗大夹杂物处形成条状裂纹源且裂纹发生疲劳扩展，最终形成纵横裂型核伤；提高钢轨钢的纯净度、加强钢轨钢冶金质量的控制和检验、减少和细化钢中非金属夹杂物的数量和尺寸是防止纵横裂型核伤形成的主要措施。

The fracture morphology, microstructure, chemical composition and tensile properties of a damaged rail head were tested by scanning electron microscope, optical microscope, direct reading spectrometer and tensile testing machine. The reason for formation of longitudinal-transverse kidney-shaped fatigue cracks was discussed and the solutions were proposed. The results show that under the cyclic working stress, the strip crack source was formed at the location of coarse inclusions distributed along the rolling direction in the wheel-rail contacted stress area of the rail head, and then fatigue propagation of the cracks occurred resulting in the formation longitudinal-transverse kidney-shaped fatigue cracks. Improving the purity of the rail steel, strengthening the control and inspection of metallurgical quality of the rail steel and reducing the quantity and refining the size of non-metallic inclusions were the main solutions to prevent the formation of longitudinal-transverse kidney-shaped fatigue cracks.