输电线路金具直角挂板断裂原因分析

Fracture Mechanism Analysis of the Rectangular Hanging Plate in Transmission Line

某220 kV输电线路金具直角挂板发生断裂事故。为探究其断裂原因,通过宏观检测、扫描电镜微观形貌分析、能谱分析、金相检测等方法对断裂直角挂板进行检测分析。检测结果表明:裂纹内部存在锌元素,说明直角挂板进行表面热浸镀锌处理时,原始裂纹已经存在;进一步的研究发现,该直角挂板的金相组织异常,组织中存在的网状渗碳体会导致材料的晶界脆化,在外力的作用下会形成应力集中,产生裂纹并沿晶界发展;该直角挂板在安装到线路上后,受到拉应力的作用,裂纹继续扩展至断裂事故发生。本文还对钢材中存在的网状渗碳体对其性能造成的影响,以及在实际生产中如何减少此类导致材料失效的因素展开了深入探讨,力求从根源上避免此类事故的发生,保证线路安全运行。

A fracture accident of the rectangular hanging plate occurred in a 220 kV transmission line.The fracture mechanism of the rectangular hanging plate was analyzed by means of macro inspection,scanning electron microscope(SEM)micro morphology analysis,energy spectrum analysis,metallographic inspection and so on.The test results show that there was zinc element inside the crack,indicating that the original crack already existed when the rectangular hanging plate was hot⁃dip galvanized.Further research shows that the metallographic structure of the rectangular hanging plate was abnormal,and the network cementite in the structure led to the grain boundary embrittlement of the material.Under external force,the stress concentration formed,and cracks developed along the grain boundary.After the rectangular hanging plate was installed on the line,the crack continued to expand until the fracture accident occured under the action of tensile stress.The influence of network cementite in steel on its properties and how to reduce such factors leading to material failure in actual production were also discussed,trying to avoid such accidents from the root causes and ensureing the safe operation of the transmission line.