Abstract
European and Japanese developments of technologies for coal-fired power plants employing advanced steam conditions have resulted in Fe-Cr alloys that appear to have acceptable strength up to 620°C (1148°F) or possibly 650°C (1202°F). However, these alloys have relatively low Cr contents (up to 13 percent), which are marginal for the formation of protective oxide scales at these temperatures. Since there is no practical experience with alloys of this type in steam at elevated temperatures, information on their oxidation behavior in steam, in particular their rate of oxidation, is needed. This paper reports an assessment of the available information on steam oxidation of Fe-Cr alloys. It appears that the 9-12Cr and the 2-3Cr alloys oxidize at essentially the same rate at 550°C (1022°F), but the higher-Cr alloys provide somewhat better protection at the higher temperatures of interest (up to 700°C/1292°F). However, the oxidation rates are still fast, since the predominant scales formed are based on magnetite. It will be important for lifetime prediction to determine if the scale grows according to a parabolic or linear rate law; this point is not well resolved by examination of existing data. Routes for promoting the formation of more protective, Cr-rich scales on the more highly-alloyed are being explored and some show good promise.
| Original language | English |
|---|---|
| Journal | NACE - International Corrosion Conference Series |
| Volume | 2002-April |
| State | Published - 2002 |
| Event | Corrosion 2002 - Denver, United States Duration: Apr 7 2002 → Apr 11 2002 |
Funding
This work was carried out as part of program FEAA061, "Materials for Ultra-Supercritical Steam Power Plants," funded by the U.S. Department of Energy under contract no. DE-AC05-00OR22725 with UT-Battelle LLC. The authors are grateful to colleagues at the Oak Ridge National Laboratory, especially Drs. J. C. Griess and R. W. Swindeman, for input and helpful discussions. This program is part of an overall DOE-and Energy Industries of Ohio-funded program on "Boiler Materials for Ultrasupercritical Coal Power Plants," and the authors are also grateful to members of the consortium participating in this program for review and comment on the paper.
| Funders | Funder number |
|---|---|
| U.S. Department of Energy |
Keywords
- Advanced steam conditions
- Ferritic steels
- Linear oxidation
- Magnetite scales
- Parabolic oxidation
- Steam oxidation