某45钢电机转轴早期断裂失效分析

Fracture Failure Analysis of a 45 Steel Motor Rotating Shaft

本文对某机床45钢电机转轴早期异常断裂情况,采用直读光谱、扫描电子显微镜、硬度计、蔡司金相显微镜等分析设备对转轴进行了检测和分析,内容包括对断口位置的化学成分、夹杂物,宏观形貌和微观组织,以及显微维氏硬度。结果表明:化学成分和非金属夹杂物、带状组织、晶粒度,转轴基材符合国标对45钢的要求。断裂主要原因是轴与轴套接触位置配合不当,应力集中导致在断裂源处发生热摩擦,使转轴表面有过热重熔现象,形成了粗大显微组织,降低了转轴表面强度,从而加快疲劳裂纹的形成和扩展,导致早期异常断裂的发生。

In this paper,the failure analysis of the rotating shaft of 45 steel duo to early abnormal fracture was carried out.Scanning electron microscope,hardness meter and zeiss metallographic microscope were used to detect,including chemical composition,mechanics,macroscopic and microscopic morphology,metallographic structure and micro-vickers hardness test.The results show that the chemical composition,nonmetallic inclu-sion,banded structure,grain size and rotating shaft substrate meet the requirements of national standard for 45 steel.The main reason for the fracture is due to improper matching of the contact position between the shaft and the shaft sleeve,stress concentration leading to thermal friction at the frac-ture source,causing overheating and remelting on the surface of the shaft,forming coarse microstructure,reducing the surface strength of the shaft,accelerating the formation and expansion of fatigue cracks,and leading to the occurrence of early abnormal fracture.