High temperature oxidation of heat-resistant alloys is considerably accelerated in the presence of water vapor which can severely reduce the longevity of high temperature components. The purpose of this study was to assess and compare the oxidation resistance of several Ni-Cr, Ni-Cr-Fe alloys, and Fe-Cr-Ni austenitic stainless steels in humidified air. The laboratory test program included 1,008 hour oxidation exposures at 649°C, 760°C and 871°C in air + 5 vol. % H2O and air + 10 vol. % H2O. Alloy performances were ranked by assessing weight change and extent of attack which includes metal loss, average internal penetration, and maximum internal penetration. The average and maximum internal penetrations were measured using optical microscopy. It was found that the Ni-based alumina-forming alloy exhibited superior performance compared to the other alloys selected in the study. Among chromia-formers, Fe-based alloys were found to be more susceptible to increased degradation in humidified air.

Subject
Test methods, Water, Oxidation resistance, Stainless alloys, Materials performance, Nickel based alloys, Metal loss, Vapors, Corrosion attacks, Penetration, Metals, Alloys, Oxidation
Keywords:
Ni-Cr alloys, Ni-Cr-Fe alloys, Fe-Cr-Ni alloys, oxidation resistance, water vapor, chromia-and alumina-formers
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2009
Association for Materials Protection and Performance (AMPP)
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