Abstract: Failure of heat exchanger at a wash of circulating water factory was analyzed by optical microscope, X-ray fluorescence spectrometer, X-ray diffraction (XRD), electrochemical test analysis method. The results show that chemical composition of heat exchanger didn’t meet the standard of 20# steel. Due to the surface of the vascular bundles scaling there is a serious corrosion. inside surface of tubes exist iron oxide layer which led to the under-deposition corrosion because different concentration of oxygen inside and outside deposition form corrosion battery. Therefore, under-deposit corrosion is the main the main cause of tubes perforation.

Key words: 　Heat exchanger ,  Perforation , Corrosion , Failure

摘要： 　    采用光学显微镜、Ｘ射线荧光光谱仪、Ｘ射线衍射仪（ＸＲＤ）、电化学测试等分析手段，对某洗化厂循环水换热器管束钢（２０＃ 钢）进行失效分析。分析结果表明：管束材质成分不符合标准２０＃ 钢成分的要求，管束材质的变化将影响其耐蚀性；又由于管束内表面结垢发生较为严重的垢下腐蚀，管束内表面存在氧化铁垢层使垢层内外形成氧浓差电池，构成大阴极小阳极腐蚀原电池。所以，垢下腐蚀是引起管束穿孔的主要原因。

关键词: 　换热器 , 　穿孔 , 　腐蚀 , 　失效