2021 Fiscal Year Research-status Report
Development of a novel multi-directional thermomechanical process to optimize the microstructure of Oxide-Dispersion-Strengthened (ODS) ferritic steel
| Project/Area Number |
20K14445
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| Research Institution | National Institute for Fusion Science |
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Principal Investigator |
申 晶潔 核融合科学研究所, ヘリカル研究部, 助教 (80824747)
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| Project Period (FY) |
2020-04-01 – 2023-03-31
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| Keywords | ODS steel / Recrystallization / Creep property / Irradiation effects |
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| Outline of Annual Research Achievements |
In the fiscal year 2021, the creep tests for recrystallized 12Cr ODS steel at 700℃ were continued. Moreover, to investigate the stability of oxide particles under irradiation, 2.8 MeV Fe2+ irradiation was conducted at room temperature (RT) and 400℃ at the High Fluence Irradiation Facility, The University of Tokyo. The irradiation doses were 0.5, 2, and 15 dpa (displacements per atom), which were estimated at the peak damage based on SRIM calculation. After irradiation, nanoindentation hardness test was carried out up the depth of 150 nm. As for the cold rolled specimen, the hardness was not evidently changed up to 15 dpa at both RT and 400℃, indicating that deformation dislocations provide the sinks for the irradiation defects. By contrast, the hardness of recrystallized specimen was increased with increasing irradiation dose at both RT and 400℃. Microstructural characterization for revealing the hardening mechanisms is ongoing.
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| Current Status of Research Progress |
Current Status of Research Progress
2: Research has progressed on the whole more than it was originally planned.
Reason
Ion irradiation experiments at room temperature and 400℃ were performed, and the nanoindentation hardness test of irradiated specimens was conducted. The microstructural characterization will be carried out to indicate the microstructure changes after irradiation. Creep test machines and the accelerator for high energy ion irradiation experiments need maintenance. The machine time will be arranged after maintenance in the FY2022.
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| Strategy for Future Research Activity |
According to the schedule of this study, creep tests at various temperature and load ranges will be conducted. Regarding the irradiated specimens, the microstructure will be characterized to indicate the hardening mechanisms after irradiation and the stability of the oxide particles. Besides, high energy ion irradiation experiments at 500 and 700℃ will be planned to investigate the temperature dependence of irradiation effects on ODS steel via joint usage/research with other universities and/or institutes.
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| Causes of Carryover |
Due to the COVID-19 pandemic, the domestic and international conferences were held virtually so that there was no need for travel expenses in FY2021.
This amount of budget would be used in the next fiscal year for machining specimens, ion irradiation experiments, and microstructural characterization.
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