Comparison of Oxidation Resistance of Several Heat Resistant Steels in Supercritical Water

The electrochemical property and oxidation resistance of Super304H, P92 and 15CrMo steels after being oxidized in supercritical water at temperature of 554, 645 ℃ and pressure of 24 MPa for 44 h were studied by electrochemistry impedance spectra (EIS) and weight increment test. The surface morphology and phase analysis of oxide films were examined by SEM and XRD. The results show that the mass of Super304H steel had no obvious change. The mass increment of P92 steel and 15CrMo steel was evident after oxidation, but there was no obvious difference between them. Surface product on Super304H was composed of tiny acicular or granular oxides containing Fe and Cr elements, while the oxide scales on P92 steel and 15CrMo steel were composed of Fe3O4 particles. The impedance sequence of the samples in NaCl solution after oxidation in supercritical water at 554 ℃ was P92