Oxidation behavior analysis of a ferritic ODS steel in supercritical Water

Abstract

Abstract The corrosion behavior of 14Cr ODS steel exposed to the supercritical water (SCW) at 600 °C under 25 MPa with the dissolved oxygen content of 300 ppb was investigated. The weight gain measurement and corrosion layers analysis were used to determine the corrosion behavior and corrosion mechanism of the 14Cr ODS steel. The results indicate that the 14Cr ODS steel exposed in this work possesses better corrosion resistance than the other ODS steel with a similar composition. Both uniform corrosion regions and nodular corrosion regions can be seen on the exposed specimens, which is due to the bimodal microstructure of the ODS steel. The corrosion products have a multi-layer structure, including the outer oxide layer, the inner oxide layer, and the transition layer. The oxide in the inner layer is FeCr2O4. The oxides in the outer layer change from the initial Fe3O4 to Fe2O3 with the increase of exposure time. The possible corrosion mechanism is analyzed as well, combining with the microstructure characters of the 14Cr ODS steel.