Corrosion behavior of austenitic and ferritic steels in supercritical water

Abstract

The general corrosion behavior of austenitic and ferritic steels (316L, 304, N controlled 304L, and 410) in supercritical water is investigated in this paper. After exposure to deaerated supercritical water at 480 °C/25 MPa for up to 500 h, the four steels studied were characterized using gravimetry, scanning electron microscopy/energy dispersive X-ray spectroscopy (SEWEDS), X-ray photoelectron spectroscopy (XPS), and X-ray diffraction (XRD). The results show that the 316L steel with a higher Cr and Ni content has the best corrosion-resistance performance among the steels tested. In addition to the oxide layer mixed with Fe3O4 and (Fe,Cr)3O4 that formed on all the samples, a Fe3O4 loose outer layer was observed on the 410 steel. The corrosion mechanism of stainless steels in supercritical water is discussed based on the above results.