Corrosion Behavior of Modified UNS N08367 Austenitic Steel in Supercritical Water

摘要

The corrosion behavior of a modified UNS N08367 austenitic steel (mod. UNS N08367) exposed to deaerated supercritical water at 650° C and 25 MPa for exposure times to 1,000 h was investigated using weight gain measurement and oxide structure analysis. The morphologies, microstructures, and chemical compositions of oxide films grown on mod. UNS N08367 were analyzed using scanning electron microscopy/energy-dispersive spectroscopy and x-ray diffraction. A double-layered structure was identified in the oxide films. The loose, outer magnetite layer was rich in Fe, while the relatively compact magnetite/spinel-mixed inner layer was rich in Cr. Polyhedron-shaped surface oxide crystals grew with the exposure time. The general corrosion rates of mod. UNS N08367-1 (solution-annealed) and mod. UNS N08367-2 (aging at 600° C for 50 h) were 0.03366 mg/dm^sup 2^-h^sup -1^ and 0.02939 mg/dm^sup 2^-h^sup -1^, respectively, after 1,000 h exposure. [PUBLICATION ABSTRACT]