主变黄铜抱箍断裂失效分析

Fracture Failure Analysis of Main Transformer Brass Hoop

抱箍作为主变开关连杆的重要紧固件,其安全稳定运行非常重要。针对某主变有载调压开关连杆上抱箍发生断裂事故,采取宏观检查、化学成分、金相分析,分析抱箍发生断裂的原因并提出改进措施。结果表明:根据黄铜中加入元素的"锌当量系数"推算,该黄铜抱箍的Zn含量超过了45%,组织呈单相β组织,这种组织的强度和塑性较差,在紧固螺栓的作用下出现开裂,最终发生了脆性断裂。

As the important fastener of the main change switch connecting rod, the hoop is very important for safe and stable operation. Macroscopic inspection, chemical composition and metallographic analysis are carried out for the cause of the breakage of the hoop and improvement measures are proposed. Based on the ″zinc equivalent coefficient″ of the elements added to the brass, the brass hoop has a Zn content of more than 45% and the tissue is in a single phase β. According to the results, this kind of tissue is inferior in strength and plasticity, causing cracks under the action of fastening bolts and finally brittle fracture.