断路器轴销断裂机理分析

Circuit Breaker Shaft Pin Fracture Failure Mechanism Analysis

某断路器的操作过程中发生40Cr轴断裂,从断口分析、化学成分分析、硬度检测、金相分析等对轴断裂的原因进行分析。结果表明:轴针端部盲孔过渡弧曲率半径偏小,加工粗糙程度大而造成的应力集中,是销轴发生断裂失效的重要的外部因素;同时轴针端盲孔的过渡圆弧性能偏低,工作中造成应力集中,并萌生疲劳裂纹源,裂纹不断扩展,最终导致了低周疲劳断裂。

A 40 cr shaft pin broke when a type of circuit breaker was running. The research of the reasons for the fracture, which was based on the fracture of shaft pin, its chemical composition , its hardness testing and metallographic examination method, found that the most important external factors were excessively small holes transition arc R and the gravity concentration caused by roughness in processing. At the same time, the needle side blind holes transition arc performance on the low side, fatigue crack source expanding crack, eventually led to the low gravity concentration from work, and initiation of cycle fatigue fracture.