Oxidation Behavior of Austenitic Steels in Supercritical Water Containing Dissolved Oxygen

Oxidation tests of austenitic steel Super304H and HR3C were conducted at 550-600 °C in supercritical water under 25 MPa with the dissolved oxygen content. The oxidation rate of Super304H rapidly increased with increasing temperature, while the weight change of HR3C at 600 °C is slightly larger than that at 550 °C. A double-layer oxide scale developed on Super304H and HR3C steel, which was made up of an Fe-rich outer layer and a Cr-rich inner layer. The criterion contents of Cr were calculated for Super304H and HR3C. The effect of temperature and the Cr content on oxidation rate and oxide composition were discussed.