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Tanigawa, Hiroyasu; Sokolov, M. A.*; Sawahata, Atsushi*; Hashimoto, Naoyuki*; Ando, Masami; Shiba, Kiyoyuki; Enomoto, Masato*; Klueh, R. L.*
Journal of ASTM International (Internet), 6(5), 10 Pages, 2009/05
The master curve (MC) method works when the transition fracture toughness values follow the MC, and once the value is scaled properly, the MC is usually independent of the type of steel or the type of test specimen. This method is very much depending on the assumption that the fracture initiation points are homogeneously distributed and its initiation mechanism is independent on test temperature. The reduced-activation ferritic/martensitic steels (RAFs), such as F82H (Fe-8Cr-2W-0.2V-0.04Ta), has Al
O
Ta(V,Ti)O composite inclusions, or simple Ta(V)O inclusions, and shows inhomogeneous distribution, and it was revealed that that RAFs which contain Ta could initiate the facture in the different mechanism at lower temperature as the composite inclusions become fragile, and this should be considered when the toughness measured with small size toughness specimen which is usually tested at lower temperature.
Kim, S.-W.*; Tanigawa, Hiroyasu; Hirose, Takanori; Koyama, Akira*
Journal of ASTM International (Internet), 5(8), 8 Pages, 2008/09
Depending on the pulse lengths, the operating conditions, and the thermal conductivity, oscillating temperature gradients will cause elastic and elastic-plastic cyclic deformation giving rise to (creep-) fatigue in the structural first wall and blanket components. Small specimen testing technology and related remote-control testing techniques are indispensable for the effective use of the limited volumes of materials test reactor and proposed intense neutron sources. In order to perform an accurate fatigue lifetime assessment using small specimen, the effects of material factors (surface morphology, inclusion, etc.) on low cycle fatigue (LCF) is mandatory. In this work, the LCF properties of F82H IEA heat were examined for three kinds of surface morphology with miniaturized hourglass-type fatigue specimens (SF-1), and the correlation between LCF crack initiation/propagation and distribution of inclusions also revealed by using SF-1 specimen. Fracture surfaces and crack initiation sites were investigated by SEM.
Ando, Masami; Tanigawa, Hiroyasu; Wakai, Eiichi; Stoller, R.*
no journal, ,
The correlation between tensile property and micro-hardness with its micro-deformation zone in neutron/ion irradiated Ferritic/Martensitic steels was examined. The materials were F82H IEA heat and heat treatment variants. The neutron irradiation was performed in HFIR up to 9 dpa at 573 K. The ion-beam irradiation experiment was also carried out at the TIARA facility. Hardness and tensile test were performed at irradiated specimens. Irradiation hardening occurred by neutron/ion irradiation at 
573 K about F82H IEA and F82H heat treatment variants. The lowest hardness is an over-tempered F82H specimen before/after irradiation. For result of tensile tests, the increase of yield stress in an over-tempered F82H is less than that of F82H IEA. These results are similar to the tensile properties of TIG weldment irradiated at 573 K. This shows that a condition of heat treatment for smaller radiation hardening in F82H steel was obtained in this experiment.
Nishiyama, Yutaka; Tobita, Toru; Onizawa, Kunio
no journal, ,
A study on intergranular embrittlement of reactor pressure vessel steels due to thermal aging and neutron irradiation has been performed. Three kinds of A533B steel with grain boundary phosphorus concentrations of 9%, 17% and 32% were used. Fracture toughness tests in the ductile-to-brittle transition temperature region have been conducted using 1T-CT and PCCv specimens for these materials. To evaluate a conservative value of T0 for this material, the SINTAP lower tail analysis method was applied. The results indicated that the difference in T0 values from E1921 method and the SINTAP method was 
C for the highest Pgb material and negligible for the other materials. The detailed fracture toughness results and fractographic analyses for the materials after thermal aging and neutron irradiation are presented.