Studies on High Temperature Corrosion of Austenitic Heat-resistant Steels Super 304H/10Cr18Ni9Cu3NbN in Simulated and Real Combustion Gas Atmospheres

High temperature corrosion behavior of austenitic heat-resistant steel Super 304H/10Cr18Ni9Cu3NbN in simulated and real combustion gas conditions was investigated in this paper. An scanning electron microscopy (SEM) equipped with an energy dispersive spectrometer (EDS) was employed to characterize the morphology and cross-section of specimens cut from experimental tubes. Results show different corrosion resistance of Super 304H and 10Cr18Ni9Cu3NbN steels under a simulated condition. High temperature corrosion is a complicated process containing the molten complex alkali-iron tri-sulphate corrosion, high temperature oxidation and sulfuration. The corrosion rate might be controlled by sulfuration of metals. Finally, the exfoliation mechanism of high temperature scales was put forward which is mainly related to the temperature fluctuation and different thermal coefficients of expansion of multi-corrosion layers.