The fracture of an axle pin in a large air compressor was analyzed by fractography, metallogra-phy, stress analysis.The results showed that fracture of axle pin was caused by improper heat treatment.

• 采用断口分析、金相检验及受力分析等方法；从微观机理及宏观力学两方面分析了轴销断裂的原因；并建立力学模型考察其疲劳强度.；试验结果表明；造成轴销断裂的主要原因是热处理工艺控制不当