发电机张紧螺栓断裂原因分析

摘要

发电机张紧螺栓在使用中连续发生断裂。通过宏观检验、化学成分分析、硬度测试和金相检验等手段分析了该螺栓断裂的原因。结果表明，螺纹部分有脱碳现象，从而在应力集中的螺纹根部引发了裂纹并扩展；螺栓未淬透，降低了力学性能，加大了裂纹扩展的速率，两者共同作用导致螺栓早期断裂。%Fracture of tension bolts used in a generator occurred continually in service.The reason for the bolt fracture was investigated by means of macroscopic examination,chemical compositions analysis,hardness test,and metallographic examination.The results show that decarburized layer is present in the thread portion,causing cracks to form and to extend in the thread root due to stress concentration.Furthermore,the bolts are not throughout hardened,thus reducing their mechanical properties and accelerating extension of the crack.The premature fracture of the bolts is attributed to above-named both favtors.