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对断裂失效的螺栓件进行宏观分析、化学成分分析、力学性能试验、断口分析、金相分析和硬度测试,结果表明,该螺栓属于起裂螺纹根部表面的单向弯曲疲劳断裂,断裂螺栓起裂区断口为穿晶和少量沿晶混合的疲劳断口,扩展区断口为穿晶疲劳断口,终断区很窄,为韧窝断口,说明螺栓起裂过程除受到弯曲疲劳应力外,还受到氢的作用,螺栓终断时弯曲应力并不大。螺栓镀锌后残留氢偏高和工作中存在振动是导致螺栓发生疲劳断裂的主要原因。
The results show that the bolt belongs to the unidirectional bending fatigue fracture of the root surface of the starting rupture thread, and the rupture of the rupture bolt The fracture of the zone is the fatigue fracture of transgranular and a small amount of intergranular mixed. The fracture of the extension zone is the transgranular fatigue fracture, and the final fracture zone is very narrow, which is the fracture of dimple. It shows that in addition to the bending fatigue stress, the bolt fracture process is affected by hydrogen The role of the bolt when the bending stress is not large. Bolt galvanized residual hydrogen high and there is vibration in the work is the main cause of fatigue fracture of the bolt.