重型汽车骑马螺栓断裂分析

The analysis of facture of the U-bolt in the heavy truck

本文采用组织分析、扫描电镜断口及化学分析,对重型汽车骑马螺栓断裂原因进行分析,结果表明在车辆使用中,由于骑马螺栓拧紧力矩减小引起板簧侧向窜动,对骑马螺栓产生多次小能量冲击,形成附加弯矩,同时在螺栓热处理过程中表面贫碳降低表面的疲劳强度,最终发生弯曲疲劳断裂。

The facture of the U-bolt in the heavy truck was researched by microstructure, SEM and chemical analysis. The result showed that the tightening torque loss in U-bolt caused the lateral movement of leaf spring, which produced frequent small energy impact and additional bending moment to U-bolto Also, the carbon depleted surface after heat treatment reduced the fatigue strength of the surface, leaded to ultimate bending fatigue fracture