On oxidation film structure of SIMP steel exposed in stagnant oxygen-saturated LBE at 600 C

To understand the impact of multilayered oxide films on the liquid-metal resistance, SIMP steels with three different Si levels were investigated. A novel composite oxidation film, namely amorphous SiO2 packed by Cr2O3, was formed along the prior high-angle grain boundaries in internal oxidation zone to impede the inward diffusion of oxygen. Evolved into the inner layer, the amorphous SiO2 films stayed there, while Cr2O3 transformed into FeCr2O4. Moreover, outward diffusion of chromium facilitated the transformation from lower sublayer to upper sublayer in inner layer. This multilayer plays a critical role in improving the oxidation resistance of SIMP steel.