LN3-2-6X井直线电机抽油机导向轮轴在使用过程中发生断裂。采用宏观观察、无损检测、力学性能测试、化学成分分析及金相检验等方法对该导向轮轴的断裂原因进行了分析。结果表明:该导向轮轴在服役过程中承受交变载荷,从而发生疲劳断裂。裂纹起源于轮轴外表面与腹板焊接处,轮轴材料力学性能不合格、材料组织出现异常以及腹板焊接质量差对裂纹扩展起到了一定的促进作用。

The guide wheel shaft of linear motor pumping unit in LN3-2-6X well fractured in use. The fracture causes of the guide wheel shaft were analyzed by macroscopic observation, nondestructive testing, mechanical properties testing, chemical composition analysis and metallographic examination. The results show that the guide wheel shaft beers alternating load during service, resulting in fatigue fracture. The cracks originated from the welding of the outer surface of the axle and the web. The unqualified mechanical properties of axle materials, abnormal microstructure of materials and poor welding quality of webs played a certain role in promoting crack propagation.