Corrosion behavior and microstructural evolution of ASTM A182 Grade 92 steel in liquid sodium at 650 °C

ASTM A182 Grade 92 steel was exposed to liquid sodium at 650 °C to investigate the effect of oxidation on microstructural evolution. Comparisons were made to the same material exposed to argon gas at 650 °C. In the sodium-exposed specimens, intergranular oxidation and chromium depletion were observed at the near-surface. With the argon-exposed specimen, however, this behavior at the surface was not observed. At the near-surface in specimens exposed to 650 °C liquid sodium, it was mostly M23C6 carbide that was observed, whereas a M2(W,Mo) phase was predominant in the bulk steel matrix in specimens exposed to both 650 °C sodium and argon.