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Nakata, Toshiya; Komazaki, Shinichi*; Kono, Yutaka*; Tanigawa, Hiroyasu
Metallurgical Journal, LXIII(Sp.), p.146 - 150, 2010/08
The small punch (SP) test is one method of small specimen test technology. We constructed a model for finite element analysis (FEA) using the Ramberg-Osgood equation to try to estimate tensile properties from the SP test. The results showed that the SP curve obtained from previous experiments could be reproduced by FEA to the point where the necking behavior of SP specimens became prominent. It was found that the relationship between the Mises equivalent stress at the point giving the largest equivalent plastic strain, and the total strain based on the Ramberg-Osgood equation, in the SP specimens, agreed well with the true stress-true strain curve plotted from tensile test measurements, and could thus be used to evaluate the 0.2% proof stress, tensile strength and uniform elongation.
Tanigawa, Hiroyasu; Hirose, Takanori; Shiba, Kiyoyuki; Kasada, Ryuta*; Wakai, Eiichi; Serizawa, Hisashi*; Kawahito, Yosuke*; Jitsukawa, Shiro; Kimura, Akihiko*; Kono, Yutaka*; et al.
Fusion Engineering and Design, 83(10-12), p.1471 - 1476, 2008/12
Times Cited Count：78 Percentile：97.68(Nuclear Science & Technology)Reduced activation ferritic/martensitic steels (RAFMs) are recognized as the primary candidate structural materials for fusion blanket systems. F82H, which were developed and studied in Japan, was designed with an emphasis on high temperature properties and weldability. The database on F82H properties is currently the most extensive available among the existing RAFMs. The objective of this paper is to review the R&D status of F82H and to identify the key technical issues for the fabrication of an ITER Test Blanket Module (TBM) suggested by recent achievements in Japan.
Ando, Masami; Li, M.*; Tanigawa, Hiroyasu; Grossbeck, M. L.*; Kim, S.-W.; Sawai, Tomotsugu; Shiba, Kiyoyuki; Kono, Yutaka*; Koyama, Akira*
Journal of Nuclear Materials, 367-370(1), p.122 - 126, 2007/08
Times Cited Count：17 Percentile：71.98(Materials Science, Multidisciplinary)Irradiation creep behavior of the F82H and several JLF-1 steels have been measured up to 5 dpa, using helium-pressurized creep tubes irradiated in HFIR. These tubes were pressurized with helium to hoop stress levels of 0 to 400 MPa for irradiation temperature. The results of F82H and JLF-1 with 200 MPa hoop stress showed small creep strains (
0.15%) after irradiation. Irradiation creep rate in these steels is linearly dependent on the applied stress less than 200 MPa. However, at higher hoop stress level, the creep rate of them is nonlinear. The creep compliance coefficient for F82H and JLF-1 at 300 
C is very small values. These data contribute to a part of materials database for ITER Test blanket design work.
Ando, Masami; Tanigawa, Hiroyasu; Shiba, Kiyoyuki; Jitsukawa, Shiro; Kono, Yutaka*; Koyama, Akira*; Li, M.*; Stoller, R. E.*
Nihon Kinzoku Gakkai-Shi, 71(7), p.559 - 562, 2007/07
Times Cited Count：0 Percentile：0.01(Metallurgy & Metallurgical Engineering)no abstracts in English
Nakata, Toshiya; Tanigawa, Hiroyasu; Shiba, Kiyoyuki; Komazaki, Shinichi*; Fujiwara, Mikio*; Kono, Yutaka*; Koyama, Akira*
Nihon Kinzoku Gakkai-Shi, 71(2), p.239 - 243, 2007/02
Times Cited Count：4 Percentile：33.15(Metallurgy & Metallurgical Engineering)no abstracts in English
Nakata, Toshiya; Komazaki, Shinichi*; Nakajima, Motoki*; Kono, Yutaka*; Tanigawa, Hiroyasu; Shiba, Kiyoyuki; Koyama, Akira*
Nihon Kinzoku Gakkai-Shi, 70(8), p.642 - 645, 2006/08
Times Cited Count：4 Percentile：34.08(Metallurgy & Metallurgical Engineering)no abstracts in English
Hamada, Shozo; *; *; Hishinuma, Akimichi; *; Koyama, Akira*
Journal of Nuclear Materials, 212-215, p.458 - 463, 1994/00
Times Cited Count：1 Percentile：17.86(Materials Science, Multidisciplinary)no abstracts in English
Nakata, Toshiya; Tanigawa, Hiroyasu; Komazaki, Shinichi*; Kono, Yutaka*
no journal, ,
no abstracts in English
Nakata, Toshiya; Tanigawa, Hiroyasu; Ando, Masami; Komazaki, Shinichi*; Kono, Yutaka*
no journal, ,
no abstracts in English
Chikada, Nobuyoshi*; Hayashi, Shigenari*; Ukai, Shigeharu*; Kono, Yutaka*; Otsuka, Satoshi; Kaito, Takeji
no journal, ,
The mechanistic study was carried out on high-temperature strength of 9Cr-ODS ferritic steel that has a duplex microstructure of tempered martensite and residual-alpha ferrite. Microstructure characterizations were performed by micro and nano-hardness tests and microstructure observations after normalizing and tempering. Resistance to tempering was shown to increase with volume fraction of residual-alpha ferrite. This result is consistent with creep rupture test result. Individual strength of tempered martensite and residual-alpha ferrite was estimated from nano-hardenss and inter-particle spacing. In the presentation, discussion will be performed on the mechanism of residual-alpha ferrite formation as well as the effect of residual-alpha ferrite on high-temperature strength improvement.
Ando, Masami; Tanigawa, Hiroyasu; Li, M.*; Nakata, Toshiya; Stoller, R.*; Kono, Yutaka*
no journal, ,
Irradiation creep of RAF/M steels has been recognized as one of the most important properties for engineering data due to the ITER test blanket structural design. The objective of this work is to examine an irradiation creep mechanism by using a microstructural observation in pressurized tubes of irradiated F82H and JLF-1. Irradiation was performed in the HFIR up to 5 dpa at 573 and 773 K. A small piece was cut from the center of each irradiated tube after diametral measurement. The microstructural examination with FIBed samples and replica films was carried out using a TEM. The creep strain for all steels at 573 and 773 K shows linear dependence on the applied hoop stress up to 
250 MPa and 100 MPa, respectively. As results of extraction replica samples irradiated at 573 K, finer spherical precipitations were observed in highest hoop stress level. The detailed discussion will be presented along with the results of microstructure observation for irradiated specimens.
Nakata, Toshiya; Tanigawa, Hiroyasu; Shiba, Kiyoyuki; Komazaki, Shinichi*; Kono, Yutaka*; Koyama, Akira*
no journal, ,
no abstracts in English
Nakata, Toshiya; Tanigawa, Hiroyasu; Ando, Masami; Komazaki, Shinichi*; Kono, Yutaka*
no journal, ,
Reduced activation ferritic/martensitic steels are the first candidate material for fusion reactor, and will be used as the structural materials of ITER test blanket modules (TBM). TBM will be assembled by welding various parts, it is important to be clearly mechanical properties of weldments to qualify TBM structure. In this paper, unirradiated mechanical properties of weldments, which is consisted of weld metal, heat affected zone (HAZ) and base metal region, obtained from TIG and EB welded F82H IEA-heat were evaluated by charpy impact and creep test. The creep tests were carried out at temperatures of 773-873 K and at stress levels of 150-260 MPa, with the specimens which include weld metal and HAZ region in the gage section. In these conditions, rupture time of weldments yield to about 100-1000 hours. The mechanism of these properties deterioration will be discussed based on the detailed analyses on microstructure changes.
Tanigawa, Hiroyasu; Nakata, Toshiya*; Kim, D.-H.*; Ando, Masami; Shiba, Kiyoyuki; Hirose, Takanori; Komazaki, Shinichi*; Kono, Yutaka*; Koyama, Akira*
no journal, ,
Reduced activation ferritic/martensitic steels (RAFMs) are recognized as the primary candidate structural materials for fusion blanket systems, as they have been developed based on massive industrial experience of ferritic/martensitic steel replacing Mo and Nb of high chromium heat resistant martensitic steels (such as modified 9Cr-1Mo) with W and Ta, respectively. F82H (Fe-8Cr-2W-V, Ta) is the RAFM which is designed with emphasis on high temperature property and weldablility. Fusion blanket system will be suffer from high temperature/high pressure of its coolant, heat flux of fusion plasma etc., which cause creep and fatigue load on blanket system. On the other hand, the current blanket system design have complicated structure to achieve its function, and require long weld to fabricate its structure. In this paper, unirradiated creep and fatigue properties of base metal and weldments of F82H will be reviewed, and critical issues for design will be discussed.
Nakata, Toshiya; Komazaki, Shinichi*; Kono, Yutaka*; Tanigawa, Hiroyasu
no journal, ,
The small punch (SP) test method has many. However, because of the complex deformation process, it is difficult to evaluate the stress and strain distributions in the SP test specimen. The ability to evaluate material's tensile properties using the SP test would be of great engineering significance. In this research, in order to establish a new procedure for evaluating tensile properties by the SP test, we attempted the stress and strain analyses of the SP test specimen using the finite element method. As the result, the relationship between the maximum von-Mises equivalent stress in the SP specimen and the strain calculated based on the Ramberg-Osgood's law was in good agreement with the true stress-true strain curve obtained from the actual tensile test within uniform elongation. These results indicate that the tensile properties such as yield strength, tensile strength and uniform elongation can be estimated by the SP test and the subsequent finite element analysis.
Komazaki, Shinichi*; Chida, Shinji*; Nakata, Toshiya; Kono, Yutaka*; Tanigawa, Hiroyasu
no journal, ,
no abstracts in English
Shibata, Hiromi*; Kono, Yutaka*; Sato, Takahiro; Okubo, Takeru; Yamazaki, Akiyoshi; Ishii, Yasuyuki; Yokoyama, Akihito; Koka, Masashi
no journal, ,
Shibata, Hiromi*; Kono, Yutaka*; Sato, Takahiro; Okubo, Takeru; Yamazaki, Akiyoshi; Ishii, Yasuyuki; Yokoyama, Akihito; Koka, Masashi
no journal, ,
no abstracts in English
