某风电场多台3 MW风力发电机组在运行1.5 a(年)后，叶片连接螺栓频繁发生断裂。通过化学成分分析、力学性能测试、金相分析及断口分析等方法，对其中一台风力发电机组的叶片连接螺栓断裂原因进行了分析。结果表明：该风电场叶片连接螺栓的断裂原因主要是材料中存在大量的氧化硅夹杂物，以及制造过程中热处理工艺控制不当导致的晶粒粗大等原因。且叶片连接螺栓安装及定期维护时预紧力分散度较大，使得螺栓在运行中受到复杂的应力条件下发生疲劳断裂失效。

The high-strength bolts, which were applied to the 3 MW Wind turbine blades in a wind power plant, were fractured frequently after running for 1.5 years. The reasons of the fracture were analyzed by means of chemical composition analysis, mechanical properties testing, metallographic analysis, fracture surface analysis, and so on. The results show that the main reasons of the fracture of the bolts were lots of silicon oxide inclusions in the material, bulky grains caused by improper heat treatment, and so on. In addition, the pretightening force was relatively dispersive in the installation and maintenance process, which led to fatigue fracture failure of the bolts under the complicated stress.