Abstract
A family of alumina-forming austenitic (AFA) stainless steels is under development for use in aggressive oxidizing conditions from ~600-900 °C. These alloys exhibit promising mechanical properties but oxidation resistance in air with water vapor environments is currently limited to ~800 °C due to a transition from external protective alumina scale formation to internal oxidation of aluminum with increasing temperature. The oxidation behavior of a series of AFA alloys was systematically studied as a function of Cr, Si, Al, C, and B additions in an effort to provide a basis to increase the upper-temperature oxidation limit. Oxidation exposures were conducted in air with 10% water vapor environments from 800-1000 °C, with post oxidation characterization of the 900 °C exposed samples by electron probe microanalysis (EPMA), scanning and transmission electron microscopy, and photo-stimulated luminescence spectroscopy (PSLS). Increased levels of Al, C, and B additions were found to increase the upper-temperature oxidation limit in air with water vapor to between 950 and 1000 °C. These findings are discussed in terms of alloy microstructure and possible gettering of hydrogen from water vapor at second phase carbide and boride precipitates.
Original language | English |
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Pages (from-to) | 337-357 |
Number of pages | 21 |
Journal | Oxidation of Metals |
Volume | 75 |
Issue number | 5-6 |
DOIs | |
State | Published - Jun 2011 |
Funding
Acknowledgements The authors thank B.A. Pint for providing comparative FeCrAlY material, suggestions regarding the addition of high levels of B, and for helpful comments on this manuscript. The authors also thank S. Dryepondt and Govindarajan Muralidharan for helpful comments in reviewing this manuscript and Dorothy Coffey for the FIB sample preparation. Funding from the U.S. Department of Energy’s Energy Efficiency and Renewable Energy Industrial Technologies Program and collaboration with the SHaRE User Facility at ORNL is also acknowledged. ORNL is managed by UT-Battelle, LLC for the US DOE under contractDE-AC05-00OR22725. Notice: This submission was sponsored by a contractor of the United States Government under contract DE-AC05-00OR22725 with the United States Department of Energy. The United States Government retains, and the publisher, by accepting this submission for publication, acknowledges that the United States Government retains, a nonexclusive, paid-up, irrevocable, worldwide license to publish or reproduce the published form of this submission, or allow others to do so, for United States Government purposes.
Keywords
- Alumina
- Internal oxidation
- Multi-phase alloy oxidation
- Stainless steel
- Third-element effect
- Water vapor