某电梯公司生产的材料为Q345A钢的电梯驱动轴在短期内发生断裂失效, 采用化学成分分析、金相检验、硬度测试、扫描电子显微镜分析等方法对驱动轴断裂原因进行了分析。结果表明: 该驱动轴断裂属性为多源旋转弯曲疲劳断裂;断裂源位于驱动轮盘和驱动轴过渡的环焊缝热影响区的应力集中处, 加之驱动轴表面加工刀痕明显, 且存在硬而脆的马氏体非正常组织, 进一步加剧了该处的应力集中, 在扭转力作用下萌生多源裂纹, 裂纹不断扩展最终导致断裂。

Fracture failure happened to an elevator drive shaft with material of Q345A steel after service for a short time, and the fracture reasons were analyzed by means of chemical compositions analysis, metallographic examination, hardness test and scanning electronic microscope analysis. The results show that fracture property of the drive shaft was multisource rotary bending fatigue fracture. The fracture sources located at the stress concentrated heat affected zone of traction wheel and the actuating shaft welded construction. At the same time, there were obvious machining marks and hard and brittle martensite at the fracture source, which further intensified the stress concentration. So cracks emerged and fracture happened under the action of the twisting force.