| About this Abstract |
| Meeting |
2022 TMS Annual Meeting & Exhibition
|
| Symposium
|
Environmentally Assisted Cracking: Theory and Practice
|
| Presentation Title |
Environmental Creep Behavior of a 9Cr Martensitic Steel in CO2 and Air |
| Author(s) |
Richard P. Oleksak, Kyle A Rozman, Jeffrey A Hawk, Ömer N Doğan |
| On-Site Speaker (Planned) |
Richard P. Oleksak |
| Abstract Scope |
Future supercritical CO2 (sCO2) power systems require structural alloys which are resistant to creep in CO2-rich environments. Herein we studied the environmental degradation of a 9Cr martensitic steel during creep testing in 1 bar of flowing CO2 or air at 650 °C. We found that CO2 caused a clear reduction in creep strength relative to air, which was associated with an increased depth of cracking initiated in the oxide scale. Microstructural analyses revealed this cracking was caused by a sub-surface zone of coarsened metal carbides resulting from carbon uptake during the CO2 exposure. The existence of this brittle carburized zone, and its subsequent oxidation behavior, facilitated and perpetuated the propagation of cracks initiated in the oxide scale. This work indicates that creep-oxidation interactions represent an important materials consideration for sCO2 power cycles and confirms that limiting steel carburization is critical for reducing long-term degradation in these environments. |
| Proceedings Inclusion? |
Planned: |
| Keywords |
Environmental Effects, Mechanical Properties, Iron and Steel |