Corrosion behaviors of pre-oxidized Al-containing Fe alloys in molten NaCl–KCl salts

The effect of pre-oxidation on the corrosion resistance of two Fe-based high-Al alloys, named Advanced Creep resistance Enhanced Stainless steel (ACES) and Alumina-forming Duplex Stainless Steel (ADSS), in molten NaCl–KCl salts at 750 °C for 500 h has been studied. Corrosion behavior of the alloys was evaluated through weight loss, electron microscopy, X-ray analysis, and elemental analysis. The results show that pre-oxidized ACES formed a stable aluminum oxide layer, which provided enhanced corrosion resistance. In contrast, pre-oxidized ADSS experienced significant oxide layer degradation and higher weight loss than those without pre-oxidation. This contrasting performance is attributed to the selective dissolution of alloying elements such as Cr and Mn, which influenced the integrity of the oxide scales.