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Otsuka, Satoshi; Shizukawa, Yuta; Tanno, Takashi; Imagawa, Yuya; Hashidate, Ryuta; Yano, Yasuhide; Onizawa, Takashi; Kaito, Takeji; Onuma, Masato*; Mitsuhara, Masatoshi*; et al.
Journal of Nuclear Science and Technology, 60(3), p.288 - 298, 2023/03
Times Cited Count：4 Percentile：76.47(Nuclear Science & Technology)JAEA has been developing 9Cr-oxide dispersion strengthened (ODS) tempered martensitic steel(TMS) as a candidate material for the fuel cladding tubes of sodium-cooled fast reactors(SFRs). The reliable prediction of in-reactor creep-rupture strength is critical for implementing the 9Cr-ODS TMS cladding tube in the SFR. This study investigated the quantitative correlation between the creep properties of 9Cr-ODS TMS at 700 
C and the dispersions of nanosized oxides by analyzing the creep data and the material's nanostructure. The possibility of deriving a formula for estimating the in-reactor creep properties of 9Cr-ODS TMSs based on an analysis of the nanostructure of neutron-irradiated 9Cr-ODS TMSs was also discussed. The creep properties of 9Cr-ODS TMS at 700 C closely correlated with the dispersion of nanosized oxide particles. The correlation between creep-rupture lives and nanosized oxide particle dispersion was determined using existing creep models. The elucidation of correlation between the stress exponent of secondary creep rate and the nanostructure is essential to enhance future modeling reliability and formulation.
Oka, Hiroshi*; Tanno, Takashi; Yano, Yasuhide; Otsuka, Satoshi; Kaito, Takeji; Hashimoto, Naoyuki*
Journal of Nuclear Materials, 572, p.154032_1 - 154032_8, 2022/12
Times Cited Count：3 Percentile：66.21(Materials Science, Multidisciplinary)9Cr oxide dispersion strengthened steels with slightly different nitrogen concentrations (0.0034 - 0.029 wt%) were prepared and their creep property at 973 K was investigated with microstructural characterization before and after the creep test. The creep strength decreased significantly as the nitrogen concentration increased. Microstructural observation revealed that, in the higher nitrogen concentration specimen, coarse Y-rich inclusions were found along the boundary between transformed ferrite region and residual ferrite region. The solubility difference of nitrogen in 
and 
phase would induce the localized increment of nitrogen concentration in the boundary region during the austenitizing process, resulting in the thermodynamic destabilization and subsequent coarsening of the dispersed oxide particles. The rows of creep voids were found near the rupture part of the crept specimen, suggesting that the coarse inclusions were the starting point of creep void formation and the subsequent premature fracture.
Masaki, Nobuo*; Kato, Koji*; Yamamoto, Tomohiko; Miyagawa, Takayuki*; Fujita, Satoshi*; Okamura, Shigeki*
Nihon Kenchiku Gakkai Gijutsu Hokokushu, 28(68), p.81 - 84, 2022/02
no abstracts in English
Watanabe, Katsutoshi; Shindo, Masami; Nakajima, Hajime; Koikegami, Hajime*; Higuchi, Makoto*; Nakanishi, Tsuneo*; Sahira, Kensho*; Marushichi, Koki*; Takeiri, Toshiki*; Saito, Teiichiro*; et al.
JAERI-Research 97-009, 62 Pages, 1997/02
JAERI-Research-97-009.pdf:4.82MB
no abstracts in English
Watanabe, Katsutoshi; Nakajima, Hajime; Koikegami, Hajime*; Higuchi, Makoto*; Nakanishi, Tsuneo*; Saito, Teiichiro*; Takatsu, Tamao*
JAERI-Research 95-001, 58 Pages, 1995/01
JAERI-Research-95-001.pdf:4.31MB
no abstracts in English
*; Watanabe, Katsutoshi; Tsuji, Hirokazu; Nakajima, Hajime
JAERI-M 93-148, 34 Pages, 1993/07
no abstracts in English
Fujita, Mitsutane*; *; Nakajima, Hajime; *; Ueno, Fumiyoshi*; Kano, Shigeki*; Iwata, Shuichi*
Computer Aided Innovation of New Materials,II,Pt. 1, p.81 - 84, 1993/00
no abstracts in English
280mm t); ; Yoshida, Eiichi;
PNC TN9410 91-099, 106 Pages, 1991/02
This stady was performed in order to confirm the influence of sampling method on Creep properties of 9Cr-Mo steel forgings which are promising as candidate materials for steam generator of large scale fast breeder reactor. This results are to be reflected on fundation of materials strength standard. Test materials are four kinds of 9Cr-Mo steel forgings (thickness:250280mmt) such as Mod.9Cr-1Mo (F4, F8 heats), 9Cr-1Mo-Nb-V(G3 heat), 9Cr-2Mo (H6 heat) steels. Results obtained are summarized as follows. (1)In order to evaluation of fundamental material properties, creep-rupture data on three kinds of 9Cr-Mo steel forgings such as Mod.9Cr-1Mo, 9Cr-2Mo and 9Cr-1Mo-Nb-V steels was obtained up to 10,000 hours. (2)The Mod.9Cr-1Mo steel exhibited most excellent creep-rupture strength and the 9Cr-2Mo steel was the worst among the three. (3)The effect of the sampling location of specimens on creep strength was not significant for Mod.9Cr-1Mo steel. But for 9Cr-1Mo-Nb-V steel and 9Cr-2Mo steel, longer creep rupture time was observed with spcimens taken from just below the center of the surface with direction of L, and shorter creep rupture time was observed for those taken from t/2 thickness at the center with direction of Z. (4)Creep strength of 9Cr-2Mo steel was lower than that of Mod.9Cr-1Mo (F4, F8)and 9Cr-1Mo-Nb-V steel. But rupture elongation and reduction of area of 9Cr-2Mo steel was greater than hat of other three materials, irrespective of the sampling location of specimens.
; Ogawa, Yutaka; Nagasaki, R.
Tetsu To Hagane, 59(7), p.949 - 954, 1973/07
no abstracts in English
Kanayama, Hideyuki; Nagae, Yuji; Onizawa, Takashi; Wakai, Takashi; Imo, Kazumichi*
no journal, ,
no abstracts in English
