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Takahashi, Osamu*; Shibui, Yohei*; Xu, P. G.; Harjo, S.; Suzuki, Tetsuya*; Tomota, Yo*
Quantum Beam Science (Internet), 4(1), p.16_1 - 16_15, 2020/03
Tanigawa, Hiroyasu; Hashimoto, Naoyuki*; Sakasegawa, Hideo*; Klueh, R. L.*; Sokolov, M. A.*; Shiba, Kiyoyuki; Jitsukawa, Shiro; Koyama, Akira*
Journal of Nuclear Materials, 329-333(1), p.283 - 288, 2004/08
Times Cited Count:19 Percentile:75.21(Materials Science, Multidisciplinary)Reduced-activation ferritic/martensitic steels (RAFs) were developed as candidate structural materials for fusion power plants. In a previous study, it was reported that ORNL9Cr-2WVTa and JLF-1 (Fe-9Cr-2W-V-Ta-N) steels showed smaller ductile-brittle transition temperature (DBTT) shifts compared to IEA modified F82H (Fe-8Cr-2W-V-Ta) after neutron irradiation up to 5 dpa at 573K. This difference in DBTT shift could not be interpreted as an effect of irradiation hardening, and it is also hard to be convinced that this difference was simply due to a Cr concentration difference. To clarify the mechanisms of the difference in Charpy impact property between these steels, various microstructure analyses were performed.
Tanigawa, Hiroyasu; Hashimoto, Naoyuki*; Sokolov, M. A.*; Klueh, R. L.*; Ando, Masami
Fusion Materials Semiannual Progress Report for the Period Ending (DOE/ER-0313/35), p.58 - 60, 2004/04
1TCT fracture toughness specimens of F82H-IEA steel were fatigue precracked and sliced in specimen thickness wise for microstructure analysis around the precrack. The microstructure around the precrack was observed by optical microscopy (OM), scanning electron microscopy (SEM), orientation imaging microscopy (OIM), and transmission electron microscopy (TEM). TEM samples around the crack front were prepared by focused ion beam (FIB) processor. The fracture surfaces of tested 1TCT specimens were also observed. OM observation showed that the precrack penetration was straight in the beginning, and then tended to follow a prior austenite grain boundary and to branch into 2 to 3 directions at the terminal. SEM and OIM observations revealed that the both microstructures around the precracks and ahead of the precrack had turned into cell structure, which is the typical microstructure of fatigue-loaded F82H. TEM images and inverse pole figures obtained from the crack-front region confirmed this structure change.
Ishii, Toshimitsu; Omi, Masao; Saito, Junichi; Hoshiya, Taiji; Ooka, Norikazu; Jitsukawa, Shiro; Eto, Motokuni
Journal of Nuclear Materials, 283-287(Part.2), p.1023 - 1027, 2000/12
Times Cited Count:12 Percentile:62.16(Materials Science, Multidisciplinary)no abstracts in English
Nishiyama, Yutaka; Onizawa, Kunio; Idei, Yoshio; Suzuki, Masahide
JAERI-Research 2000-047, 32 Pages, 2000/10
no abstracts in English
;
JNC TN9400 2000-035, 164 Pages, 2000/03
High Strength Ferritic/Martensitic Steel (PNC-FMS : 0.12C-11Cr-0,5Mo-2W-0.2V-0.05Nb), developed by JNC, is one of the candidate materials for the long-life core of large-scale fast breeder reactor. Ductile brittle transition temperature (DBTT) was tentatively determined in 1992 in material design base standard of PNC-FMS. Howevcr, specimen size effect on impact property and upper shelf energy (USE) have not been evaluated. ln this study, effects of specimen size, thermal aging and neutron irradiation on the charpy impact property of PNC-FMS were evaluated, using together with recently obtained data. The design value of USE and DBTT as fabricated and each correlation of aging and irradiation effects were determined. The results are summarized as follows. (1)lt was found that USE is related to (Bb) as USE=m(Bb), where B is specimen width, b is ligament size and both m and n are constant. For PNC-FMS, n value is equal to 1.4. It's possible to determine n value from USE (J) for full size specimen using the correlation: n=1.3810 USE + 1.20. (2)lt was clarified that DBTT is correlated with (BKt) as DBTT=p(logBKt)+q, where Kt is elastic stress concentration factor and both p and q are constant. For PNC-FMS, the correlation is as follows: DBTT=119(logBKt)-160. (3)DBTT estimated at the irradiation temperature from 350 to 650 C for sub size specimen (width and height are 3 and 10 mm, respectively), was below 180 C, based on the design value of DBTT as fabricated and each correlation of aging and irradiation effects.
Suzuki, Masahide; Eto, Motokuni; Nishiyama, Yutaka; Fukaya, Kiyoshi; *; *
Journal of Nuclear Materials, 191-194, p.1023 - 1027, 1992/00
Times Cited Count:11 Percentile:70.41(Materials Science, Multidisciplinary)no abstracts in English
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Nihon Gakujutsu Shinkokai Tainetsu Kinzoku Zairyo Dai-123 Iinkai Kenkyu Hokoku, 27(1), p.11 - 20, 1986/00
no abstracts in English
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Trans.Iron Steel Inst.Jpn., 23, p.842 - 845, 1983/00
no abstracts in English
Takamizawa, Hisashi; Nishiyama, Yutaka
no journal, ,
no abstracts in English
Takamizawa, Hisashi; Nishiyama, Yutaka
no journal, ,
no abstracts in English
Takamizawa, Hisashi; Nishiyama, Yutaka
no journal, ,
Irradiation embrittlement of reactor pressure vessel steels is usually predicted based on ductile-to-brittle transition temperature shift obtained by Charpy impact tests for unirradiated and irradiated specimens. It is important to understand the uncertainty in the evaluation by Charpy impact test when giving margins for structural integrity assessment using embrittlement trend curves and when discussing the need for surveillance specimens obtained from the weld heat affected zone. In this study, we modeled the temperature dependence of Charpy absorbed energy based on about 1900 datasets of unirradiated and irradiated Japanese and U.S. materials. Then we used Bayesian statistics to construct an evaluation model that could take into account the variation in absorbed energy, the number of tests, and test temperatures for each dataset. In my presentation, we will discuss the results of analyses for the effects of irradiation, difference between Japanese and U.S. materials, and product form on the uncertainty of the Charpy ductile-to-brittle transition temperature.