电流互感器铝合金法兰开裂失效分析

Failure Analysis on Cracking of an Aluminum Alloy Flange for Current Transformer

某福建沿海地区用于电流互感器的铝合金法兰发生多处开裂,采用宏观检验、化学成分分析、金相分析、扫描电镜以及能谱分析等方法对该法兰开裂原因进行了分析。结果表明:法兰开裂均起始于螺栓孔处,为在腐蚀介质和应力共同作用下发生的应力腐蚀开裂;法兰螺栓扭紧力高、服役环境氯离子含量高以及法兰所用铝合金材料应力腐蚀开裂敏感性高等是造成该法兰开裂的主要原因。最后针对法兰开裂原因提出了预防措施。

Multiple cracking was found on an aluminum flange used for the current transformer in coastal region of Fujian province. Means such as macro examination,chemical composition analysis,metallographic analysis,scanning electron microscope and energy spectrum analysis,and so on were utilized to investigate the causes for the cracking. The results show that all the cracks initiated from the bolt holes,and the failure of the flange was stress corrosion cracking（SCC） under the coaction of corrosive environment and stress. The high tightening force of the bolts,the high Clconcentration of the service environment and the high sensitivity to SCC of the aluminum alloy were the main causes for the cracking of the flange. Finally,preventive measures were put forward according to the cracking causes of the flange.