The failure analysis of the leakage of the economizer tube of the waste heat boiler in the energy factory is investigated in this study. The experimental methods included metallurgical and mechanical properties examination, XRD analyses of the corrosion products, and fractural observation of the failed tube. The results show that although the material and mechanical properties of the failed tube, were inferior to those of the new one, most of them were still satisfactory to the criterion requirement. From SEM observation, it is clear that the crack initiated in the outer surface and propagated toward the inner surface of the tube. The fracture, through the entire thickness of the tube, was identified to be intergranular. The crack formation is not dominated by overall degradation in the tube, but might result from a combination with the decrease in the toughness. The toughness degradation in the grain boundary of the economizer tube must have taken place during the fin welding process.
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