为弄清核电厂海水过滤器转子连接螺栓发生断裂失效的原因，采用体视显微镜、扫描电镜和能谱仪观察螺栓断口形貌，分析腐蚀产物成分。利用Marc有限元软件分别模拟了剪切载荷和轴向拉伸载荷作用下螺栓中的应力分布，并讨论了螺栓的失效机理。结果表明：距离法兰支撑面最近的第一扣螺纹牙承受的载荷最大；在径向交变剪切载荷和轴向拉伸载荷的长期作用下，螺纹根部的微裂纹沿弧切线方向扩展，最终导致疲劳断裂。

To figure out the reasons for fracture failure of rotor connection bolts of seawater filter in a nuclear power plant, the fracture morphology of the bolts was observed by means of stereo microscopy and scanning electron microscopy, and the composition of corrosion products was analyzed by energy dispersive spectroscopy. The stress distributions in bolts under shear load and axial tensile load respectively were simulated by Marc finite element software, and the failure mechanism of bolts was discussed. The results show that the first screw thread nearest to the flange support face bore the greatest load. Under the long-term action of radial alternating shear load and the axial tensile load, the micro crack at the screw root expanded along the tangent direction of arc, and finally led to fatigue fracture.