某变电站电流互感器接地引线螺栓断裂分析

Analysis on Fracture of CT Grounding Lead Bolt in a Substation

针对某变电站电流互感器接地引线螺栓发生断裂失效,采用宏观检查、化学成分、硬度检测、金相及断口分析等试验,分析螺栓断裂失效原因并提出改进措施。结果表明:螺栓材质为铅黄铜,锡含量超标,出现脆性的γ相组织;此外,大量铅聚集于螺栓边缘处,形成带状,破坏了材料基体的连续性,而且容易形成裂纹源,在外应力作用下,发生脆性断裂。

Aiming at the fracture and failure of the grounding lead bolt of current transformer(CT)in a substation,this paper uses the measures of macroscopic inspection and analyses on chemical composition,hardness testing,metallographic and fracture surface analysis,etc.to analyze the cause of the bolt breakage,and then puts forward improvement measures.The results shows that the bolt material is lead brass,and tin content exceeds the standard,thus appearing brittleγ-phase structure,and that in addition,a large amount of lead accumulates at the edge of the bolts,forming bands and destroying the continuity of the material matrix,easy to evolve into a crack source,with brittle fracture occurring under the action of external stress.