Study of hierarchical deformation mechanism in LPSO-type magnesium alloys using diffraction method

Shiro, Ayumi*; Shobu, Takahisa; Hagihara, Koji*; Watanabe, Masashi*

SPring-8/SACLA Riyo Kenkyu Seikashu (Internet), 10(5), p.438 - 446, 2022/10

https://doi.org/10.18957/rr.10.5.438

no abstracts in English

Effects of stress and plastic strain on hydrogen embrittlement fracture of a U-bent martensitic steel sheet

Shibayama, Yuki; Hojo, Tomohiko*; Koyama, Motomichi*; Saito, Hiroyuki*; Shiro, Ayumi*; Yasuda, Ryo*; Shobu, Takahisa; Matsuno, Takashi*; Akiyama, Eiji*

ISIJ International, 61(4), p.1322 - 1329, 2021/04

https://doi.org/10.2355/isijinternational.ISIJINT-2020-569

On the phase transformation and dynamic stress-strain partitioning of ferrous medium-entropy alloy using experimentation and finite element method

Bae, J. W.*; Jung, J.*; Kim, J. G.*; Park, J. M.*; Harjo, S.; Kawasaki, Takuro; Woo, W.*; Kim, H. S.*

Materialia, 9, p.100619_1 - 100619_15, 2020/03

https://doi.org/10.1016/j.mtla.2020.100619

Influence of applied load on oxidation in the vicinity of crack tips of stainless steel under high temperature water

Kasahara, Shigeki; Chimi, Yasuhiro; Hata, Kuniki; Hanawa, Satoshi

Zairyo To Kankyo, 68(9), p.240 - 247, 2019/09

https://doi.org/10.3323/jcorr.68.240

In order to study environment assisted cracking mechanism of stainless steel under BWR primary coolant condition, effects of applied load on oxidation in the vicinity of crack tips of CT specimens were evaluated. Loaded CT specimens were immersed in an aqueous condition at 290C as a simulated BWR coolant condition, and microstructural observation on oxide near the tips of pre-cracks was carried out. Oxide inner layers, which consisted of fine grain magnetite containing Fe and Cr were formed, and oxide outer layers consisting of large grains of FeO were observed to cover the inner layers. FEM analysis of stress and strain in the loaded CT specimen suggests that both of dislocations due to localized plastic deformation and elastic strain could play important roles to accelerate inner oxide formation in the vicinity of the crack tip of the specimens.

Recent development of nano/micro-scale analytical techniques for nuclear materials, 2; Mechanical strength research using neutron diffraction

Morooka, Satoshi; Suzuki, Hiroshi

Nihon Genshiryoku Gakkai-Shi ATOMO, 60(5), p.289 - 293, 2018/05

no abstracts in English

Saturation behavior of thermal ratcheting strain due to long range travel of temperature distribution

Okajima, Satoshi; Wakai, Takashi

Nihon Kikai Gakkai 2017-Nendo Nenji Taikai Koen Rombunshu (DVD-ROM), 5 Pages, 2017/09

It was reported that the long distance travel of temperature distribution causes a new type of thermal ratcheting, even in the absence of primary stress. In this paper, based on the results of inelastic finite element analyses, we investigated saturation behavior of thermal ratcheting strain due to long range travel of temperature distribution. As a result, we revealed that the long distance travel of temperature distribution generates plastic strain distribution made maximum at the central part. Because of the shape of the generated strain distribution, the residual stress accumulates even at the central part of the region passed through the temperature distribution. In the case with excessive long traveling of temperature distribution, the region with plastic deformation extended to the surrounding region. Otherwise, sufficient magnitude of residual stress to cause shakedown behavior accumulated on entire region, and the accumulation of the plastic strain saturated.

Evaluation of bending strain in NbSn strands of CIC conductor using neutron diffraction

Hemmi, Tsutomu*; Harjo, S.; Kajitani, Hideki*; Suwa, Tomone*; Saito, Toru*; Aizawa, Kazuya; Osamura, Kozo*; Koizumi, Norikiyo*

IEEE Transactions on Applied Superconductivity, 27(4), p.4200905_1 - 4200905_5, 2017/06

https://doi.org/10.1109/TASC.2017.2660064

Prospect for application of compact accelerator-based neutron source to neutron engineering diffraction

Ikeda, Yoshimasa*; Taketani, Atsushi*; Takamura, Masato*; Sunaga, Hideyuki*; Kumagai, Masayoshi*; Oba, Yojiro*; Otake, Yoshie*; Suzuki, Hiroshi

Nuclear Instruments and Methods in Physics Research A, 833, p.61 - 67, 2016/10

https://doi.org/10.1016/j.nima.2016.06.127

A compact accelerator-based neutron source has been lately discussed on engineering applications such as transmission imaging and small angle scattering as well as reflectometry. However, nobody considers using it for neutron diffraction experiment because of its low neutron flux. In this study, therefore, the neutron diffraction experiments are carried out using Riken Accelerator-driven Compact Neutron Source (RANS), to clarify the capability of the compact neutron source for neutron engineering diffraction. The diffraction pattern from a ferritic steel was successfully measured by suitable arrangement of the optical system to reduce the background noise, and it was confirmed that the recognizable diffraction pattern can be measured by the large sampling volume with 10 mm in cubic for an acceptable measurement time, i.e. 10 minutes. The minimum resolution of the 110 reflection for RANS is approximately 2.5 % at 8 s of the proton pulse width, which is insufficient to perform the strain measurement by neutron diffraction. The moderation time width at the wavelength corresponding to the 110 reflection is estimated to be approximately 30 s, which is the most dominant factor to determine the resolution. Therefore, refinements of the moderator system to decrease the moderation time are important to improve the resolution of the diffraction experiment using the compact neutron source. In contrast, the texture evolution due to plastic deformation was successfully observed by measuring a change in the diffraction peak intensity by RANS. Furthermore, the volume fraction of the austenite phase was also successfully evaluated by fitting the diffraction pattern using a Rietveld code. Consequently, RANS was proved to be capable for neutron engineering diffraction aiming for the easy access measurement of the texture and the amount of retained austenite.

Thermal aging effect for creep properties on Ni base refractory alloys

Ishijima, Yasuhiro; Ueno, Fumiyoshi

Proceedings of 23rd International Conference on Nuclear Engineering (ICONE-23) (DVD-ROM), 4 Pages, 2015/05

In this study, to evaluate the effect of thermal aging on creep properties of Alloy 625, we carried out creep tests on aged and solution-treated Alloy 625 at 1073 K. According to the creep test results, time-to-rupture decreased by thermal aging when test stress was more than 100 MPa, but did not change when test stress was less than 100 MPa for any specimens. In the solution-treated alloy, creep deformation behaviors changed over 100 MPa. These results show that time-to-rupture was constant because intermetallic compounds precipitated when the test stress was less than 100 MPa in solution-treated alloy. The observed relationship between creep strain rate and test time showed that the precipitation started after 100 hr for solution treated alloys. These results suggest that intermetallic compounds precipitate immediately after furnace operation. And it is appropriate to use creep data of thermal-aged Alloy 625 for the reducing roasting furnace lifetime prediction.

Analysis of plastic deformation behavior at SCC crack tip by EBSP method

Kaji, Yoshiyuki; Miwa, Yukio; Tsukada, Takashi

Nihon Kikai Gakkai M&M 2005 Zairyo Rikigaku Kanfarensu Koen Rombunshu, p.175 - 176, 2005/12

From results of analysis of plastic deformation behavior at SCC crack tip by EBSP method, the conclusions was obtained as follows: (1)Regarding to basic data for quantitative evaluation of plastic deformation behavior at SCC crack tip, we obtained relationship between plastic deformation and misorientation of grain using SSRT result for SUS316L stainless steel in high temperature water and local plastic strain was able to estimate using this relationship. (2)From experimental results of plastic strain at SCC crack and ductile crack tips using relationship between misorientation and plastic deformation, plastic strain near ductile crack tip was larger than that at SCC crack tip. Plastic deformation region was, however, corresponded to region of about one grain at crack tip for both SCC and ductile cracks.