通过对机车车辆常用件13号车钩舌所产生裂纹的宏观和微观形貌进行了研究,并对其形成机理进行了探讨。结果表明钩舌裂纹既有典型的表面裂纹又有内部微观裂纹。其产生裂纹的主要原因是铸造过程中形成的组织缺陷以及钩舌在使用过程中的冲击和摩擦、磨损产生的应力集中。 The macroscopic and microscopic appearances of the cracks produced by the coupler knuckles of the common car parts of locomotives were studied and the formation mechanism was discussed. The results show that there are both typical surface cracks and internal micro-cracks in the knuckle crack. The main reason for cracks is the formation of defects in the casting process as well as the knuckle impact and friction during wear and tear, stress concentration caused by wear.