Effect of pre-oxidation on the corrosion behavior of Fe–40Al sheet in a N2–11.2O2–7.5CO2–500 ppm SO2 atmosphere at 1273 K

A 200 μm thick Fe–40A1 sheet, produced by powder metallurgy and hot extruding, was pie-oxidized at 1373 K in air for different times and then the pre-oxidized specimens were corroded at 1273 K for up to 360 ks in a N2–11.2 vol.% O2–7.4 vol.%CO2–500 ppm SO2 atmosphere. The pre-oxidation followed a parabolic rate law, forming continuous, adherent α-Al2O3 oxide scales, accompanied by the formation of valley-like flaws. The valley-like flaws originate from the inclusion of additives in the alloy substrate. The inclusion of additives as α-Al2O3 in the Fe–40Al sheet leads to some local exfoliation of the oxide scale in the SO2 containing atmosphere. The Fe–40Al pre-oxidized for longer than 14.4 ks showed very good corrosion resistance in the N2–11.2 vol.% O2–7.4 vol.% CO2–500 ppm SO2 atmosphere, and there is little exfoliation of the oxide scale after 360 ks oxidation at 1273 K.