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Ukai, Shigeharu*; Yano, Yasuhide; Inoue, Toshihiko; Sowa, Takashi*
Materials Science & Engineering A, 812, p.141076_1 - 141076_11, 2021/04
Times Cited Count:20 Percentile:77.54(Nanoscience & Nanotechnology)FeCrAl oxide dispersion strengthened alloys are promising materials for accident tolerant fuels for light water reactors (LWRs). In these alloys, Al and Cr are key elements with important synergistic effects: enhancement of the formation of oxidation-resistant AlO
phase by Cr addition and suppression of the formation of the embrittling Cr-rich
' phase by Al addition. The solid-solution strengthening resulting from Al and Cr co-addition was investigated in this study. The solid-solution strengthening resulting from Al and Cr co-addition was investigated in this study. The Al and Cr contents were systematically varied from 9-16 at.% and 10-17 at.%, respectively, and tensile tests were conducted at 298 K, 573 K and 973 K in the as-annealed condition. The solid solution strengthening increased linearly, 20 MPa per 1 at.% Al and 5 MPa per 1 at.% Cr, at the typical LWR operational temperature of 573 K. The conventional Fleischer-Friedel and Labusch theories cannot explain this level of solid-solution strengthening. It was shown that Suzuki's double kink theory for screw dislocations reasonably predicts the solid solution strengthening by Al and Cr as well as the inverse dependency on the absolute temperature and linear dependency on the Al and Cr content.
Aghamiri, S. M. S.*; Sowa, Takashi*; Ukai, Shigeharu*; Ono, Naoko*; Sakamoto, Kan*; Yamashita, Shinichiro
Materials Science & Engineering A, 771, p.138636_1 - 138636_12, 2020/01
Times Cited Count:37 Percentile:88.92(Nanoscience & Nanotechnology)Oxide dispersion strengthened (ODS) FeCrAl ferritic steels are being developed as potential accident tolerance fuel cladding materials for the light water reactors (LWRs) due to significant improvement in steam oxidation by alumina forming scale and good mechanical properties up to high temperatures. In this study, the microstructural characteristics and tensile properties of the two FeCrAl ODS cladding tubes with different extrusion temperatures of 1100C and 1150
C were investigated during processing conditions. While the hot extruded sample showed micron sized elongated grains with strong
-fiber in
110
texture, cold pilger rolling process change the microstructure to submicron/micron size grain structure along with texture evolution to both
-fiber (
110
texture) and
-fiber ({111} texture) via crystalline rotations. Subsequently, final annealing resulted in evolution of microstructure to large grain recrystallized structure starting at recrystallization temperature of
810-850
C. Two distinct texture development happened in recrystallized cladding tubes, i.e., only large elongated grains of (110)
211
texture following extrusion temperature of 1100
C; and two texture components of (110)
211
and {111}
112
following higher extrusion temperature of 1150
C. The different texture development and retarding of recrystallization progress in 1100
C-extruded cladding tubes were attributed to higher distribution of oxide particles.
Sowa, Takashi*; Ukai, Shigeharu*; Ono, Naoko*; Yano, Yasuhide; Kaito, Takeji; Torimaru, Tadahiko*; Kimura, Akihiko*; Hayashi, Shigenari*
no journal, ,
no abstracts in English
Sowa, Takashi*; Ukai, Shigeharu*; Aghamiri, M.*; Shibata, Hironori*; Hayashi, Shigenari*; Ono, Naoko*; Sakamoto, Kan*; Hirai, Mutsumi*; Yamashita, Shinichiro
no journal, ,
no abstracts in English
Aghamiri, M. S.*; Ukai, Shigeharu*; Ono, Naoko*; Hayashi, Shigenari*; Sowa, Takashi*; Sugawara, Naoya*; Sakamoto, Kan*; Yamashita, Shinichiro
no journal, ,
Both the grain structure and mechanical properties of the fuel cladding tubes are important issues to design the material for high temperature conditions and probable accident of nuclear reactor. In this study, we compared the microstructure and tensile properties of FeCrAl-ODS steels plates and cladding tubes in different extruded, recovered and recrystallized conditions and propose the material for the application.