| Abstract Scope |
Corrosion of an austenitic Fe-Cr-Mn stainless steel (Nitronic® 32, N32) in supercritical water (25 MPa), relative to Fe-Cr-Ni stainless steel (Types 310 and 316L) was determined. Mass change measurements revealed N32 is less susceptible to corrosion than Type 316L, but more susceptible than Type 310 stainless steel after 500 h immersion at 550 °C. The relative difference in corrosion cab be explained by the protective ability of the oxide scales formed, which, for N32, consists of an outer Mn-rich (Mn,Cr)2O3 layer residing on a Cr-rich (Cr,Mn)3O4 inner layer, as revealed by X-ray diffraction and electron microscopy techniques. A rather significant Mn depletion zone accompanies corrosion, which transforms the near-surface region from austenite to ferrite. The suitability of Fe-Cr-Mn alloy fuel claddings for the supercritical water-cooled reactor concept is discussed within the context of the findings. |