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某型工程机械主泵驱动轴在疲劳试验过程发生早期断裂,通过断口形貌分析、化学成分分析、硬度测试、金相组织观察和结构应力分析等,明确该驱动轴断裂的原因。结果表明:该驱动轴的失效模式为扭转疲劳失效。驱动轴与联轴器的连接方式不合理,造成装配夹紧位置花键根部应力集中,导致裂纹形核;花键根部表面粗糙,存在加工刀痕及表面喷砂处理造成的表面损伤,为裂纹的形核提供了有利的条件;花键轴硬化层深度浅,且硬度梯度过高,抗变形能力差,有利于裂纹的扩展。
During the fatigue test, the main drive shaft of a certain type of construction machinery fractures early. Through the analysis of fracture surface morphology, chemical composition analysis, hardness test, microstructure observation and structural stress analysis, the cause of the fracture of the drive shaft is clarified. The results show that the failure mode of the drive shaft is torsional fatigue failure. The connection between the drive shaft and the coupling is unreasonable, resulting in stress concentration on the spline root in the clamping position of the assembly, which leads to nucleation of the crack. The surface of the spline root is rough, there are surface scratches caused by machining marks and surface blasting, Of the nucleation provides favorable conditions; shallow depth of the spline shaft hardened layer, and the hardness gradient is too high, anti-deformation ability is poor, is conducive to the expansion of the crack.