电站连接螺栓断裂失效分析

Failure Analysis on Fracture of Connecting Bolts in a Power Plant

采用宏观检验、化学成分分析、力学性能测试、金相检验、扫描电镜分析等方法,分析了某核电减速机轮毂与辐条连接螺栓的断裂失效原因。结果表明:螺栓断裂是由于螺栓松动后,辐条上下滑动,使螺栓承受较大的剪切应力,最终导致其多源双向疲劳断裂;螺栓材料中存在大量超尺寸脆性硅酸盐类夹杂物,在一定程度上加速了疲劳裂纹的形成和扩展。

The fracture reasons of the bolts connecting the wheel hub and spokes of a reduction gear in a nuclear power plant were analyzed by macroscopic examination,chemical composition analysis,mechanical property testing,metallographic examination and scanning electron microscopy（SEM）analysis.The results show that the failure form of the bolts was multi-source bidirectional fatigue fracture which was mainly related to the high shear stress caused by the spoke slide after the bolt looseness.A lot of super-sized brittle silicate inclusions existing in the raw material might accelerate the formation and propagation of the fatigue cracks.