Pre‑oxidation as a Means to Increase Corrosion Resistance of Commercial Superheater Steels

This study addresses the effect of pre-oxidation on the corrosion resistance of the following three commercial steels: a low-alloyed ferritic 10CrMo9-10 steel; a Nb-stabilized austenitic AISI 347 steel; and a high-alloyed austenitic Sanicro 28 steel. Samples of these three steels were pre-oxidized under various conditions and then exposed to potassium chloride (KCl) for 168 h at 550 °C under dry conditions. In the case of the ferritic 10CrMo9-10 and the austenitic AISI 347 steels, despite differences in oxide scale composition and structure, their corrosion resistance could not be improved by any of the studied pre-oxidation procedures. In contrast, pre-oxidation conditions resulting in chromium-enriched oxides improved the corrosion resistance of the high-alloyed austenitic Sanicro 28 steel in terms of oxide scale growth during exposure to KCl.