The corrosion behaviors of nuclear-grade 304 stainless steel (304SS) and ferritic- martensitic steel P92 exposed to 400°C/25 MPa supercritical water were investigated. The exposed specimens were characterized by weight gain measurement, XRD, Raman spectroscopy and SEM. It is found that both materials show general corrosion and exponential kinetics in mass gain, and the mass gain of 304SS is approximately an order of magnitude less than that of steel P92. The oxide film on 304SS is rather thin and composed of Cr2O3, α-Fe2O3, Fe2O4 and spinel, some nodules were observed on the surface. While the oxide film on steel P92 consists of α-Fe2O3, Fe2O4 and spinel, more α-Fe2O3 exist in the outer surface of the oxide film. The surface morphology of oxide film on steel P92 changes from dense particles to porous network structure with increasing exposure time, which may be relative to the dissolution of oxide.
- Ferritic-martensitic steel
- Nuclear-grade stainless steel
- Oxide film
- Supercritical water