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分析了余热锅炉中二级过热器管(材质为12CrMoV)的失效原因,结果表明管子的腐蚀和超温可能与失效过程有关,但管子表面腐蚀是二级过热器管失效的主要原因。利用X-射线衍射、金相、电子探针、红外、差热分析和化学分析等方法,研究了取自现场的腐蚀产物形貌、化学组份和结构。腐蚀产物主要是Fe_2O_3、Fe_2(SO_4)_3和铁的硫化物。因此腐蚀机制可能是Fe_2(SO_4)_3在高温下分解产生高分压的SO_3所引起的硫化和氧化。在分析结果的基础上,提出了解决这种问题的可能途径。
The failure reason of secondary superheater tube (material: 12CrMoV) in waste heat boiler is analyzed. The results show that the corrosion and over - temperature of the tube may be related to the failure process, but the corrosion of the tube surface is the main reason for the failure of the secondary superheater tube. The morphology, chemical composition and structure of corrosion products were investigated from the field by X-ray diffraction, metallography, electron probe, infrared, differential thermal analysis and chemical analysis. The corrosion products are mainly Fe 2 O 3, Fe 2 (SO 4) 3 and iron sulfide. Therefore, the corrosion mechanism may be caused by the decomposition of Fe 2 (SO 4) 3 at high temperatures to produce high partial pressure of SO 3 caused by the sulfide and oxidation. Based on the analysis results, we put forward some possible solutions to this problem.