Abstract
NF616 is a third-generation ferritic martensitic steel, developed to have better creep resistance than the prior generation T91. Unlike relatively numerous studies of T91, there is a lack of understanding of the irradiation effect on the microstructural evolution and mechanical response of NF616. This work evaluated the microstructures and radiation hardening of NF616 irradiated up to 8.2 displacement per atom (dpa) at 292 °C – 431 °C, compared with T91 from two heats. Dislocation loops were observed in all investigated samples. NF616 exhibited comparable loop size but slightly lower loop density than those in the general T91 heat at 430 °C. Cavities were only observed in NF616 at 431 °C but absent at lower irradiation temperatures (292 °C and 359 °C). Ni-rich clusters were also observed in NF616 at 431 °C, while only weak Ni-clustering were observed at lower irradiation temperatures. Compared to the general T91 heat, NF616 demonstrated better swelling resistance (e.g., one third of swelling in the general T91 heat at 430 °C), a slightly higher number density of Ni-rich clusters, and slightly lower radiation hardening. The low-carbon T91 showed the greatest hardening with the largest swelling and loop sizes, despite its lowest irradiation temperature and intermediate dose. The calculated hardening from loops, cavities and Ni-rich clusters using the classic dispersed barrier-hardening model had reasonable agreement with the experiment-derived results, with the primary hardening contribution attributed to dislocation loops.
| Original language | English |
|---|---|
| Article number | 153001 |
| Journal | Journal of Nuclear Materials |
| Volume | 552 |
| DOIs | |
| State | Published - Aug 15 2021 |
Funding
This research was sponsored by the U.S. Department of Energy ( DOE ), Office of Nuclear Energy (NE), the FY 2017 Consolidated Innovative Nuclear Research (CINR) Nuclear Science User Facilities (NSUF) program and the Light Water Reactor Sustainability (LWRS) program, under Contract no. DE-AC05-00OR22725 . The microstructure characterization and hardness measurement were completed at the Low Activation Materials Development and Analysis (LAMDA) at Oak Ridge National Laboratory (ORNL). The Talos F200X S/TEM tool provided by US DOE, Office of Nuclear Energy, Fuel Cycle R&D Program and the Nuclear Science User Facilities. This research was sponsored by the U.S. Department of Energy (DOE), Office of Nuclear Energy (NE), the FY 2017 Consolidated Innovative Nuclear Research (CINR) Nuclear Science User Facilities (NSUF) program and the Light Water Reactor Sustainability (LWRS) program, under Contract no. DE-AC05-00OR22725. The microstructure characterization and hardness measurement were completed at the Low Activation Materials Development and Analysis (LAMDA) at Oak Ridge National Laboratory (ORNL). The Talos F200X S/TEM tool provided by US DOE, Office of Nuclear Energy, Fuel Cycle R&D Program and the Nuclear Science User Facilities. This manuscript has been authored by UT-Battelle, LLC under Contract No. DE-AC05-00OR22725 with the U.S. Department of Energy. The United States Government retains and the publisher, by accepting the article for publication, acknowledges that the United States Government retains a non-exclusive, paid-up, irrevocable, worldwide license to publish or reproduce the published form of this manuscript, or allow others to do so, for United States Government purposes. The Department of Energy will provide public access to these results of federally sponsored research in accordance with the DOE Public Access Plan ( http://energy.gov/downloads/doe-public-access-plan ).
Keywords
- Cavities
- Dislocation loops
- Hardening
- Microstructure