某锅炉换热器仅运行2 h即发生换热管断裂事故, 采用光学显微镜、扫描电子显微镜、能谱仪、拉伸试验机和直读光谱仪等设备对换热管的断裂原因进行了分析。结果表明: 该换热管外壁表面在运行前就已存在原始横向裂纹和机械损伤, 在服役过程中这些裂纹和机械损伤处容易形成应力集中, 加之换热管的使用温度较低, 从而导致其在运行仅2 h后就发生早期脆性断裂。最后对该换热管的生产提出了建议。

Instruments such as optical microscope, scanning electronic microscope, energy spectrometer, tensile testing machine and direct reading spectro meter were used to analyze the fracture reason of tubes of a boiler heat exchanger which fractured after being put into operation only for 2 h. The results show that there were original cracks and mechanical damage on the surface of the tubes before their running. Stress concentration formed at the defect positions and lower service temperature together resulted in the early brittle fracture of the heat exchange tubes after 2 h operation. Some suggestion for producing the heat exchange tubes was proposed finally.