蒸发器管子管板液压胀芯轴断裂分析

某公司在进行蒸发器管子管板液压胀管过程中,胀管芯轴多次发生断裂,采用光学显微镜、扫描电子显微镜、拉伸试验机和直读光谱仪等设备对芯轴的断裂原因进行了分析。结果表明：由于液压胀过程中固定工装仅一侧固定,从而容易在芯轴螺栓螺纹根部形成应力集中,引发低周疲劳,造成芯轴疲劳断裂,缩短芯轴的使用寿命。最后对芯轴液压胀工艺提出了建议。

Fracture Analysis of Hydraulic Expanding Mandrel of Tube Hole and Tube Sheet for Steam Generator

The hydraulic tube-expanding mandrel of tube hole and tube sheet for steam generator in a company fractured repeatedly during the hydraulic pressure expanding process,and fracture reason of the mandrel was studied by instruments of optical microscope,scanning electronic microscope,tensile testing machine and direct reading spectrometer.The results show that stress concentration easily formed at the concave position of thread of the mandrel because fixed tooling was fixed only on one side,which led to low cycle fatigue fracture of the mandrel and shortening its service life.Some suggestion for hydraulic tube-expanding process was proposed finally.