35钢延长拉杆过热断裂原因分析

Analysis on reasons of overheating fracture for 35 steel extension rod

延长拉杆是输电线路重要的承载连接金具。结合一起500 kV输电线路延长拉杆断裂实例,通过对延长拉杆进行宏观检测、材料成分检测、室温和高温力学性能检测、不同热处理条件下的金相组织观察、断口形貌观察、通流试验等进行分析,研究引起延长拉杆过热断裂的原因。结果表明,当引流线夹接触不良或断开时,会导致延长拉杆通过大电流后长时间严重发热,使延长拉杆珠光体组织由层片状结构转变为球状结构,在导线拉力的作用下延长拉杆发生蠕变,承载面积减小,且抗拉强度大大降低,最终在导线拉力作用下发生断裂。研究结果对线路巡线和引流线夹安装修复工作有一定的指导意义。

Extension rod is an important load-bearing connection fitting for transmission lines. Therefore, for an example of an extension rod fracture for 500 kV transmission line, the reasons causing the overheating fracture of extension rod were investigated by macroscopic observation, material composition detection, mechanical performance detection at room temperature and high temperature, metallographic structure observation under different heat treatment conditions, fracture morphology observation and current test of extension rod. The results show that the poor contact or disconnection of jumper conductor clamper causes the extension rod to generate serious heat for a long time owing to passing through large current, the pearlite structure of the extension rod changes from lamellar structure to spherical structure, and creep occurs under the action of wire tension, then the bearing area decreases and the tensile strength has a significant drop, finally fracture occurs on the extension rod under the action of wire tension. Thus, the research provides guide for the line patrolling, installation and repair work of jumper conductor clamper.