60Si2Mn钢S钩的疲劳断裂失效分析

Failure Analysis on Fatigue Fracture of S Hook in 60Si2Mn Steel

采用光学显微镜、扫描电镜、全自动维氏硬度计、直读光谱仪、电感耦合等离子发射光谱仪等分析手段对某断裂失效的S钩进行断裂机理研究。结果表明:S钩断裂为疲劳断裂,主要原因是S钩表面脱碳层所导致的S钩表面弱化,脱碳层表面硬度远远低于芯部基体硬度,加速了疲劳裂纹源的形成,从而加速了疲劳断裂过程;并提出了相应的改进措施。

Fracture mechanism of S hook was studied by means of optical microscope, scanning electron microscope （ SEM）, automatic Vivtorinox hardness tester, direct reading spectrum and inductively coupled plasma emission spectrometer. Results showed that S hook fracture was fatigue fracture. The main reason was the surface weakening of the S hook caused by the decarburization layer on the S hook surface, and the surface hardness of the decarburization layer was much lower than that of the core substrate,which promoted the formation of the fatigue crack and accelerated the fatigue fracture process. The corresponding countermeasures were also proposed.