用于高铁变线道岔的某1Cr17Ni2不锈钢夹杆螺栓在使用约6 a（年）后发生了断裂。使用宏观检查、化学成分分析、拉伸试验和硬度测试等方法，对螺栓的断裂原因进行了分析。结果表明：螺栓断裂的主要原因是螺栓断裂部位的过渡圆角半径不符合技术要求，加剧了该部位的应力集中，在外力的作用下诱发疲劳裂纹；夹杆螺栓处于松动状态时，高速运行的火车使螺栓产生与运行方向相反的惯性力，导致螺栓于其薄弱部位发生疲劳断裂。

The clamp rod bolt of 1Cr17Ni2 stainless steel used for high-speed rail turnout fractured when the bolt was used for about six years. The fracture reasons were analyzed by methods of macroscopic examination, chemical composition analysis, tensile test, hardness testing and so on. The results show that:the main fracture reason of the bolt was that the transition fillet radius of the fracture position didn't meet the technical requirement, and it intensified the stress concentration of the position and induced fatigue cracks under the external force; when the clamp rod bolt was in a state of loose, the train at high speed would cause the bolt to create a inertia force in the opposite direction of the moving running, which led to the fatigue fracture of the bolt on its weak position.