Long-term high temperature oxidation behavior of ODS ferritics

Four oxide dispersion strengthened Fe–(13–14 at.%) Cr ferritic compositions were exposed in air and air with 10 vol.% water vapor for up to 10 000 h at 700–1100 °C. At 700–800 °C in air, the reaction rates were very low for all of the alloys compared to stainless steels. At 900 °C, a dispersion of Y2O3, compared to Al2O3, showed a distinct benefit in improving the oxidation resistance, due to a reactive element effect. However, failure occurred after 7000 h at 900 °C when only 13% Cr was present. The absence of Ti and W in one alloy appeared to result in a thinner reaction product after oxidation at 800 °C. One composition was exposed in 10 vol.% water vapor at 800 and 900 °C and in air at 1000 and 1100 °C. Under both of these conditions, there was a significant increase in the rates of oxidation. With the relatively low Cr contents in these alloys, their corrosion-limited operating temperature in air is near 900 °C.