Abstract��The chemical composition�� microstructure�� corrosion products of the leaked heat-exchanger tubes used in environmental protection equipments were analyzed by optical emission spectrometer�� optical microscope�� scanning electron microscope and energy spectrometer. Experimental results demonstrated that the failure mode of the tubes was selective corrosion�� and the main reason of the early failure for the tubes was that the tubes were serviced in high corrosion environment which contained S and Cl. The difference in the micro composition and the microstructure between the weld area and the base metal caused a difference in the electrode potential�� which formed the corrosion primary cell and caused the selective corrosion and leakage eventually.
2017, Vol. 35 
