Electrochemical corrosion characteristics of modified heat-resistant chromium steels for fast breeder steam generators

The effect was examined of Mo, C, N and V on the microstructure of modified chromium steels containing 9-12% Cr, designed for fast breeder reactor steam generators. The aim of this study was to optimize the chemical composition of the steels with regard to the fact that in contact with overheated high-pressure steam, these materials develop oxidic layers, which must be removed periodically; this is associated with the hazard of local corrosion damage. Vanadium carbonitride was found to exert the highest sensitizing effect with respect to long-time thermal exposure; in vanadium-free steels, chromium nitride plays this role. (Z.M.). 2 figs., 3 tabs., 10 refs