电网铁附件断裂失效分析

摘要

针对电网铁附件抱箍易产生断裂失效的问题,采用 SEM微观形貌观察结合原位动态拉伸试验等方法对电网抱箍断裂失效进行了相关研究.首先通过 SEM对断口微观形貌观察,初步确定断裂起源,其次通过微观组织分析等,以确定断裂方式,最后为验证上述分析的正确性,对样品进行动态原位拉伸实验研究.结果表明:抱箍微裂纹起源于夹杂物及表面缺口处,根据断口形貌判断断裂方式为韧脆断裂,而原位动态拉伸实验发现该实验抱箍试样塑性较好,服役抱箍断裂是由于抱箍制弯过程消耗了材料本身大部分塑性导致抱箍在疲劳应力下发生韧脆断裂,其中制弯工艺对铁附件抱箍起到了加工硬化的作用,相应对该工艺方法提出了改进措施.%Aimed at the problem in power grid that the fracture failure of iron accessory hoop is easy to occur,a relevant investigation of such failure was conducted by means of SEM observation combined with in-situ dynamic tensile test.At first,the fracture micro-morphology was observed by SEM and the origin of the fracture was preliminarily determined.Secondly,the fracture mode was determined by microstruc-ture analysis.Finally,in order to verify the correctness of the above-mentioned analysis,the in-situ dy-namic tensile test of the sample was carried out.The investigation result showed that the microcracks would be originated from the inclusions and surface notches and the fracture mode would be ductile-brittle fracture according to the fracture morphology,while the in-situ dynamic tensile test would find that the hoop specimen would have a better plasticity.Service hoop fracture should be due to that the bending process of the hoop would consume most of the plasticity of the material itself,resulting in ductile brittle fracture of the hoop under fatigue stress,where the cold hardening of the iron accessory hoop would take place due to its bending process.Therefore an improvement measurement of this process was put forward accordingly.