Oxidation and Corrosion Behavior of a 14Cr Oxide Dispersion Strengthened Ferritic Steel Applied for Supercritical Water Reactor

摘要

Oxide Dispersion Strengthened（ODS） ferritic steels are promising candidate advanced materials applied for Generation nuclear energy systemⅣ. In this work, a 14Cr ODS ferritic steel was prepared by mechanically alloying（MA）combined with hot isostatic pressing(HIP). High temperature oxidation tests were conducted at 700 °C for 500h and 1000 °C for 2h in air respectively to evaluate the high temperature oxidation behavior. This result shows that 14Cr ODS ferritic steel has rather good high temperature oxidation resistance, due to the high Cr content and the addition of dispersion particles Y2O3. Corrosion tests were performed in Supercritical Water (SCW) at 550 °C and 25MPa for 1000h. The corrosion rate of 14Cr ODS decreased along with the increase of the corrosion time, which indicates that a protective oxide scale has formed on the surface of 14Cr ODS, thus preventing further oxidation of the metal matrix. The oxide scale of 14Cr ODS was composed of an outer magnetite (Fe3O4) layer, a middle spinel ((Fe, Cr)3O4) layer, and an inner oxidation transition zone. After corrosion for 200h, the oxide scale of 14Cr ODS shows a high porosity, but the porosity decreased along with the exposure corrosion time. The decrease of pores can hamper the diffusion of cations and oxygen, therefore further oxidation of 14Cr ODS could be prohibited.