40Cr水泵轴断裂失效原因分析

Study on Fracture Failure of 40Cr Water Pump Shaft

针对某40Cr水泵轴在使用过程中发生的断裂现象,通过化学成分分析、金相、扫描电镜以及低倍酸洗检验等方法,分析了水泵轴材料是否符合标准要求,研究了水泵轴内部微观组织结构以及产生缺陷的原因,观察断口形貌特征并分析了其断裂原因。结果表明:不合理的调质处理使断裂泵轴组织中索氏体粗大,二次碳化物网和颗粒也变得粗大,进而降低了轴的耐腐蚀性和韧性,导致沿车削加工刀痕产生应力腐蚀裂纹,并在泵轴服役过程中逐渐扩展直至断裂。

In view of the fracture phenomenon of a 40 Cr pump shaft in the use process,the chemical composition analysis,metallographic analysis,scanning electron microscopy and acid pickling test were used to analyze whether the material of the pump shaft meets the standard requirements.The internal microstructure of the pump shaft and the causes of defects were studied.The fracture morphology characteristics were observed and the causes of fracture were analyzed.The results show that the unreasonable quenching and tempering treatment makes the sorbite in the fracture pump shaft coarse,the secondary carbide network and particles become coarse,thereby reducing the corrosion resistance and toughness of the shaft,resulting in the stress corrosion cracks along the turning tool marks,and gradually expanding until the fracture of the pump shaft during service.