材料为SAE9254钢的圆柱螺旋压缩弹簧在工作约200 h后突然发生断裂, 为分析其断裂原因, 采用显微硬度计、金相显微镜、光电直读光谱仪和扫描电镜等分别对该断裂弹簧的硬度梯度、显微组织、化学成分、断口宏观和微观形貌等进行了分析。结果表明: 弹簧断裂是疲劳断裂, 而弹簧表面的碰伤是导致其疲劳断裂的根本原因。最后, 对弹簧的生产工艺改进和正确安装使用给出了建议。

The cylinder helical compression spring made of SAE9245 steel fractured suddenly after working for about 200 h. In order to analyze the fracture reasons, the hardness gradient, microstructure, chemical compositions, fracture macro and micro morphology of the fractured spring were analyzed by using micro-hardness tester, optical microscope, optical emission spectrometer and SEM respectively. The results indicate that the failure property of the spring was fatigue fracture, and the surface damage of the spring was the main reason for the fatigue fracture. At the same time, the improvement measures of the production process and the correct installation recommendations of the spring were suggested.