Corrosion Resistance of Experimental Alloys and Coatings Under SCW Conditions

Abstract

Resistance to high temperature corrosion is one of the key challenges in future nuclear reactor material development. Iron-based materials with low Cr (<15%) content shows superior mechanical properties and high resistance to stress corrosion cracking. However, due to relatively low Cr and Ni contents, their corrosion resistances under SCW conditions are generally poor. High-Cr ferritic alloys, despite much improved corrosion resistance, are prone to embrittlement due to the precipitation of sigma phase in the microstructure. One of the materials solutions to overcome this will be to use structurally stable materials such as P91 or ODS steels as a substrate combined with a highly corrosion resistant surface coating. In this study, development of a metallic coating on P91 steel is discussed together with the evaluation of their SCW corrosion resistance. Microstructures of a few ODS steels are also evaluated.