Further insights into the mechanisms involved in the corrosion of 316L(N) austenitic steel in oxygenated liquid sodium at 550 °C

Abstract

316L(N) austenitic steel was corroded at 550 °C in liquid sodium containing ca. 200 µg g-1 dissolved oxygen from 242 h to 7704 h. NaCrO2 is formed for all immersion times, O and Na from liquid metal and Cr from steel. The oxidation front is located at the chromite / steel interface and in the steel grain boundaries. M6C carbides (M = Mo and Fe) are also formed, C from liquid sodium. NaCrO2 is dissolved until the saturation of liquid sodium in Cr is reached. The Cr solubility is higher than that of pure Cr due to the presence of dissolved oxygen.