某风力发电机浆叶的连接螺栓在力矩紧固维护过程中发生断裂。通过宏观分析、金相检验、化学成分分析、力学性能试验等方法分析了连接螺栓断裂的原因。结果表明：该连接螺栓的冶金质量较差，存在较多的非金属夹杂物并形成裂纹源。在周期性交变载荷作用下裂纹源不断扩展而未被发现，螺栓剩余工作截面变小，最终在力矩紧固维护时于螺栓与螺母咬合部位第1螺纹根部处发生断裂。

The blade connecting bolt of a wind turbine fractured during torque tightening maintenance. The fracture causes of the connecting bolt were analyzed by means of macroscopic analysis, metallographic examination, chemical composition analysis and mechanical property test. The results show that the metallurgical quality of the connecting bolt was poor, there were more nonmetallic inclusions and the crack source was formed in here. Under the action of periodic alternating load, the crack source expanded continuously without being found, and the remaining working cross section of bolt became smaller. Finally, during the torque tightening maintenance, the fracture occurred at the root of the first thread where the bolt and nut were engaged.