驱动螺栓断裂失效分析

Fracture failure analysis of driving bolts

3Cr13不锈钢驱动螺栓在服役一段时间后在螺纹处发生断裂,对其化学成分、力学性能、断口及显微组织进行观察和分析。结果表明,螺栓断裂主要是由于热处理工艺不当,导致螺栓最终服役状态并非调质态,显微组织为回火马氏体及未溶碳化物颗粒,螺栓整体硬度过高;另外,组织中存在链状及球状非金属夹杂物,螺纹部位也有多种取向的裂纹,因而螺栓在受到冲击或扭转载荷时,裂纹和非金属夹杂可能成为裂纹源,以致发生脆性断裂。

Driving bolts made of 3Cr13 stainless steel was fractured during the service. Chemical composition, mechanical properties and microstructure of the failed bolt were analysed. The results show that the inappropriate heat treatment leads anormal mierostructure to unquenched and untempered which result to the bolt failure. The microstrueture is tempered martensites and undissolved carbides that lead to high microhardness. Additionally, globular nonmetallic inclusions and muhidirectional cracks are also observed in the bolt and accelerated the failure when the bolt is suffered from a shock or a torsional load.