电机铜铝接线端子失效机理

Failure mechanism for Cu-Al transition lug of electrical machinery

铜铝接线端子可以降低构件重量和成本、发挥各自材料的性能优点,是现役电力系统中重要的连接部件,在电力系统中应用广泛。针对某电厂运行6年后发生开裂的电动泵电机铜铝接线端子,分别通过宏观检查、化学成分分析、金相检验、扫描电镜分析和X射线衍射分析等试验进行原因分析。结果表明,接线端子接头存在焊接工艺控制不良,导致接头存在塑性变形不完全、铜夹渣、孔洞等缺欠。在服役过程中,腐蚀介质在上述缺欠处聚集进而发生电化学腐蚀,裂纹萌生并进一步扩展。

Cu-Al transition lug can reduce the weight and cost of the components and give full play to the performance advantages of their materials.It is an important connecting component in the active power system and is widely used in the power system.The reasons leading to fracture for Cu-Al transition lug of electric pump after 6 years operation was analyzed by means of morphology analysis,hardness test,metallographic test,SEM and other detection means.The results show that the welding process control of the Cu-Al transition lug is poor,which is resulting in incomplete plastic deformation,copper slag inclusion,holes and other defects.The cracks were formed and further expansion during the service,which the cause of the electrochemical corrosion at the above defects.