Effect of post-annealing on the oxidation behavior of hot rolled ODS-FeCrAl steel in liquid lead

The microstructure of the hot-rolled and annealed ODS-FeCrAl steels and related oxide scales formed in the oxygen-containing liquid lead at 600 degree celsius was investigated by SEM-EDS, EBSD and TEM. The post-annealing caused partial recrystallization of hot-rolled ODS steel, which significantly reduced the intense theta-fiber (<001>||ND) and local dislocation density. After corrosion, the hot-rolled ODS steels exhibited complex and locally uneven oxide scales while the annealed ODS steels formed a uniform triple-layered oxide scale. A new insight into the relationship between oxidation depth and grain orientation was proposed, highlighting the significance of orientation-dependent dislocations on the transition of external/internal oxidation mechanisms.