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φ32钢脚疲劳性能要求3000万次,而该厂生产的钢脚只能达到2300万次左右即断裂。为分析该批φ32钢脚未达到技术要求的原因,进行了断口的宏观分析,钢脚的成分及金相组织和晶粒度分析,SEM微观断口形貌分析。实验结果发现:断裂的φ32钢脚的宏观断口形貌为较典型的疲劳断口形貌;金相组织为网状铁素体和块状铁素体;SEM观察发现断口有裂纹源区以及裂纹扩展区,且裂纹以及疲劳变形带,有较为明显的解理台阶。
φ32 steel foot fatigue performance requirements of 30 million times, while the factory production of steel feet can only reach about 23 million that is broken. In order to analyze the reasons that the batch of φ32 steel legs did not meet the technical requirements, the macro analysis of the fracture, the composition and microstructure of the steel legs, the grain size analysis and the SEM micro-fracture surface analysis were carried out. The experimental results show that the macroscopic fracture morphology of the fractured φ32 steel is a typical fatigue fracture morphology; the microstructure is reticular ferrite and massive ferrite; the SEM observation shows that there are crack source regions and crack propagation District, and cracks and fatigue deformation zone, there is a clear cleavage step.