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Shimodaira, Masaki; Ha, Yoosung; Takamizawa, Hisashi; Katsuyama, Jinya; Onizawa, Kunio
Proceedings of ASME 2023 Pressure Vessels and Piping Conference (PVP 2023) (Internet), 11 Pages, 2023/07
In the current structural integrity assessment of the reactor pressure vessel, the accurate reference temperature (T
) based on the Master Curve method is necessary. The T can be estimated by using the Mini-C(T) fracture toughness specimen in accordance with ASTM E1921 and JEAC4216, which prescribe the pre-crack straightness criteria. A requirement in ASTM E1921 has been revised in a decade to increase the accuracy and reasonability, and the applicable crack curvature has been varied by applied codes. The pre-crack curvature of the Mini-C(T) specimen might have an impact on the T because of the variation of the plastic constraint. In this work, the effect of the crack curvature on the fracture toughness (K
) evaluation using the Mini-C(T) specimen was quantitatively evaluated by using the finite element analysis (FEA) including the Weibull stress analysis, to discuss the difference in a requirement of the crack straightness in ASTM E1921 and JEAC4216. FEAs showed a possibility that the upper limit curvature would decrease the plastic constraint, and consequently obtain higher K in the Mini-C(T) specimen. Furthermore, if the upper limit curvature according to the ASTM E1921-21 was allowed, the T would be estimated as non-conservative based on the Weibull stress analysis. In contrast, the difference in (T) between the crack with upper limit curvature according to JEAC4216 and the ideal straight crack was not significant.
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.
Onizawa, Kunio; Suzuki, Masahide
Nihon Kikai Gakkai Heisei-12-Nendo Zairyo Rikigaku Bumon Koenkai Koen Rombunshu, p.431 - 432, 2000/10
no abstracts in English
Onizawa, Kunio; Tobita, Toru; Suzuki, Masahide
Effects of Radiation on Materials (ASTM STP 1366), p.204 - 219, 2000/00
no abstracts in English
Polymer, 23, p.1515 - 1518, 1982/00
Times Cited Count：13 Percentile：61.95(Polymer Science)no abstracts in English
; ; Kuriyama, Isamu
Radiation Physics and Chemistry, 16, p.481 - 485, 1980/00
no abstracts in English
Otsu, Takuyo; Tobita, Toru; Fuse, Masaharu; Yamaki, Kenichi; Terakado, Hiroshi; Nishiyama, Yutaka
no journal, ,
no abstracts in English
Tobita, Toru; Otsu, Takuyo; Nishiyama, Yutaka
no journal, ,
Fracture toughness of the neutron irradiated reactor pressure vessel steel up to a fluence of 1
10
n/cm
was performed using the 4 mm-thick miniature C(T) specimen. We evaluate fracture toughness scatter and a relation between the shifts of fracture toughness and Charpy DBTT.
