2022 Fiscal Year Annual Research 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 | Ion irradiation / Irradiation defects / Irradiation hardening / Cold rolling / Recrystallization |
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| Outline of Annual Research Achievements |
In FY2022, ion irradiation effects on cold rolled and recrystallized 12Cr ODS steel at room temperature (RT) and 673 K was investigated and reported at the Nuclear Materials Conference (NuMat2022). Results showed that large plastic deformation inducing high density of dislocations and fine grains would suppress the irradiation hardening at both RT and 673 K. Irradiation hardening of the recrystallized samples was caused by the dislocation loops, which were formed after ion irradiation at RT and 673 K. Moreover, ion irradiation experiments at 973 K were performed at Dual-Beam Facility for Energy Science and Technology (DuET), Kyoto University, using 6.4 MeV Fe3+ and 1 MeV He+ ions for the cold rolled and recrystallized samples. The results will be presented at the 21st International Conference on Fusion Reactor Materials (ICFRM-21).
In this project, a novel multi-directional cold rolling process with 90% thickness reduction can reduce the recrystallization temperature by about 300 K in the subsequent thermal annealing compared to the as-fabricated 12Cr ODS steel. This thermomechanical process improved the elongation and creep rupture time. Regarding the irradiation resistance, cold rolling can suppress the irradiation hardening by inducing large numbers of defects (dislocations, grain boundaries, etc.). Irradiation hardening of recrystallized samples at RT and 673 K was due to the formation of irradiation defects, whereas hardening at 973 K was not obviously observed.
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