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Yoshida, Masayuki*; Nishihata, Itsuki*; Matsuda, Tomoki*; Ito, Yusuke*; Sugita, Naohiko*; Shiro, Ayumi*; Shobu, Takahisa; Arakawa, Kazuto*; Hirose, Akio*; Sano, Tomokazu*
Journal of Applied Physics, 132(7), p.075101_1 - 075101_9, 2022/08
Times Cited Count：5 Percentile：67.2(Physics, Applied)Zhang, X. X.*; Knoop, D.*; Andr
, H.*; Harjo, S.; Kawasaki, Takuro; Lutz, A.*; Lahres, M.*
International Journal of Plasticity, 140, p.102972_1 - 102972_20, 2021/05
Times Cited Count：28 Percentile：94.45(Engineering, Mechanical)Woo, W.*; Naeem, M.*; Jeong, J.-S.*; Lee, C.-M.*; Harjo, S.; Kawasaki, Takuro; He, H.*; Wang, X.-L.*
Materials Science & Engineering A, 781, p.139224_1 - 139224_7, 2020/04
Times Cited Count：38 Percentile：93.57(Nanoscience & Nanotechnology)Shobu, Takahisa; Shiro, Ayumi*; Yoshida, Yutaka*
Zairyo, 69(4), p.343 - 347, 2020/04
Dislocation density is a very important physical quantity in the evaluation of fatigue of metallic materials. Generally, the dislocation density is evaluated by a scanning electron microscope. Recently, a method generated the dislocation density from the width of the X-ray diffraction profile has been proposed. In this study, we report the application of this technology to synchrotron radiation. Five diffraction profiles were obtained with a two-dimensional detector during tensile loading of the austenitic stainless steel SUS316L, and the dislocation density was calculated from the line profile analysis. As a result, the dislocation density increased sharply after plastic deformation, and the value was in good agreement with the result separately measured with a scanning electron microscope. In the future, it is expected that the line profile analysis will contribute to the elucidation of the mechanism of fatigue fracture by measuring the dislocation density from the local area in materials.
Tomota, Yo*; Ojima, Mayumi*; Harjo, S.; Gong, W.*; Sato, Shigeo*; Ung
r, T.*
Materials Science & Engineering A, 743, p.32 - 39, 2019/01
Times Cited Count：25 Percentile：80.65(Nanoscience & Nanotechnology)Xiong, Z.; Naoe, Takashi; Wan, T.; Futakawa, Masatoshi; Maekawa, Katsuhiro*
Procedia Engineering, 101, p.552 - 560, 2015/03
Times Cited Count：1 Percentile：62.19(Engineering, Multidisciplinary)Very high-cycle fatigue behaviour of SUS316L, which is used as the structural material of the spallation neutron sources, was investigated through the ultrasonic fatigue test with the strain rate of 10
s
. Cross-sectional hardness distributions of the fatigue-failed specimens for solution annealed (SA) and cold worked (CW) 316L were measured to understand the cyclic hardening or softening. In addition, the tensile tests of the fatigue-failed specimens were performed at room temperature. Furthermore, the nonlinear ultrasonic system was used for evaluating the dislocation density variation. The results showed the cyclic hardening in the region of very high-cycle fatigue in the case of SA. In contrast, in the case of 10%CW, cyclic softening occurred when the number of cycles below 10
and followed by cyclic hardening. In the case of 20%CW, cyclic softening was observed when the number of cycles below 10
, while cyclic hardening occurred subsequently.
Kumagai, Masayoshi*; Akita, Koichi; Imafuku, Muneyuki*; Oya, Shinichi*
Advanced Materials Research, 996, p.39 - 44, 2014/08
Times Cited Count：6 Percentile：93.39(Engineering, Mechanical)The microstructural features of shot and laser peened austenitic stainless steels were studied using line profile analysis with X-rays. Although both specimens had similar residual stress profiles toward the depth direction, the microstructural features were different not only on the original surfaces of the specimens but also to several micrometers in depth. The dislocation densities of the SP specimen were greater than that of the LP specimen. And the crystallite sizes of the SP specimen were smaller than that of the LP specimen.
; Katano, Y.; Shiraishi, K.
Journal of Nuclear Science and Technology, 14(10), p.723 - 730, 1977/10
Times Cited Count：13no abstracts in English
Shobu, Takahisa; Shiro, Ayumi*
no journal, ,
no abstracts in English
Harjo, S.; Kawasaki, Takuro; Aizawa, Kazuya; Tomota, Yo*
no journal, ,
no abstracts in English
Shobu, Takahisa; Yasuda, Ryo*; Shiro, Ayumi*; Yoshida, Yutaka*; Tokuda, Susumu*; Shibano, Junichi*; Kumagai, Masayoshi*
no journal, ,
A dislocation density increases and fatigue failure of the structure occur, when a metal is deformed. In this study, dislocation density of a broken 0.3 mm thick SUS316L specimen was calculated by line profile analysis obtained by high energy synchrotron X-ray diffraction method, and a relationship between fatigue fracture and dislocation density was evaluated. As a result of the analysis, it was revealed that the dislocation density abruptly increases as approaching the fracture part. In addition, it was revealed that the bcc structure appeared in the fcc structure which is the basic structure in the fracture part. In steel, the increase in dislocation density is closely related to the increase in material strength, and the material strength of steel with bcc structure is known to be higher than that with fcc structure. So, it seems that the structure has changed due to a sharp increase in dislocation density at the fracture part.
Kurosawa, Masaya*; Yoshida, Yutaka*; Sugino, Yoshito*; Tanno, Takashi; Yano, Yasuhide
no journal, ,
no abstracts in English
in situ neutron diffractionIto, Tatsuya; Ogawa, Yuhei*; Gong, W.; Mao, W.; Kawasaki, Takuro; Okada, Kazuho*; Shibata, Akinobu*; Harjo, S.
no journal, ,
no abstracts in English
