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Fujihara, Hiro*; Toda, Hiroyuki*; Ebihara, Kenichi; Kobayashi, Masakazu*; Mayama, Tsuyoshi*; Hirayama, Kyosuke*; Shimizu, Kazuyuki*; Takeuchi, Akihisa*; Uesugi, Masayuki*
International Journal of Plasticity, 174, p.103897_1 - 103897_22, 2024/03
Times Cited Count：0Hydrogen(H) embrittlement in high-strength aluminum(Al) alloys is a crucial problem. H accumulation at the interface of precipitates in Al alloy is considered to cause embrittlement. However, there is no quantitative knowledge regarding the interaction between H distribution and stress field near cracks. In this study, using a multi-modal three-dimensional image-based simulation combining the crystal plasticity finite element method and H diffusion analysis, we tried to capture the stress distribution near the crack, its influence on the H distribution, and the probability of crack initiation in the experimental condition. As a result, it was found that grain boundary cracks transition to quasi-cleavage cracks in the region where the cohesive energy of the semi-coherent interface of MgZn
precipitates decreases due to H accumulation near the tip. We believe the present simulation method successfully bridges nanoscale delamination and macroscale brittle fracture.
X-ray synchrotron diffractionLi, H.*; Liu, Y.*; Zhao, W.*; Liu, B.*; Tominaga, Aki; Shobu, Takahisa; Wei, D.*
International Journal of Plasticity, 165, p.103612_1 - 103612_20, 2023/06
Times Cited Count：2 Percentile：78.7(Engineering, Mechanical)In order to clarify the strength properties of Co-free maraging steel, tensile experiment using high energy synchrotron X-ray diffraction was performed. Diffraction profiles from the martensitic and austenitic phases were obtained, and their strength and width were observed to vary as loading. Analysis of the diffraction profiles showed that the content of martensite in the as-aged material decreased slowly at low stress levels and decreased rapidly at high stress levels. On the other hand, the austenite phase in the as-solution materials was significantly transformed the martensite phase as the stress increased. It was clarified to be responsible for their respective strength properties.
Wei, D.*; Gong, W.; Tsuru, Tomohito; Lobzenko, I.; Li, X.*; Harjo, S.; Kawasaki, Takuro; Do, H.-S.*; Bae, J. W.*; Wagner, C.*; et al.
International Journal of Plasticity, 159, p.103443_1 - 103443_18, 2022/12
Times Cited Count：27 Percentile：98.49(Engineering, Mechanical) neutron diffractionWei, D.*; Gong, W.; Tsuru, Tomohito; Kawasaki, Takuro; Harjo, S.; Cai, B.*; Liaw, P. K.*; Kato, Hidemi*
International Journal of Plasticity, 158, p.103417_1 - 103417_17, 2022/11
Times Cited Count：22 Percentile：97.48(Engineering, Mechanical)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)
Nb with the L1 structureOkamoto, Norihiko*; Takemoto, Shohei*; Chen, Z. M. T.*; Yamaguchi, Masatake; Inui, Haruyuki*
International Journal of Plasticity, 97, p.145 - 158, 2017/10
Times Cited Count：11 Percentile：49.82(Engineering, Mechanical)Aoyagi, Yoshiteru*; Tsuru, Tomohito; Shimokawa, Tomotsugu*
International Journal of Plasticity, 55, p.43 - 57, 2014/04
Times Cited Count：42 Percentile：87.14(Engineering, Mechanical)UFGMs with a grain size less than 1 
m exhibits remarkable material and mechanical properties, and a computational model predicting these properties is desired in the field of materials science and engineering. When grains are of the submicron order, dislocation loops are hardly generated from Frank-Read sources smaller than the grain size. In this study, we develop a crystal plasticity model considering the effect of the grain boundary and dislocation source. We thoroughly investigate the effect of dislocation behavior on the material properties of UFGMs.
Aoyagi, Yoshiteru*; Kobayashi, Ryotaro*; Kaji, Yoshiyuki; Shizawa, Kazuyuki*
International Journal of Plasticity, 47, p.13 - 28, 2013/08
Times Cited Count：25 Percentile：71.33(Engineering, Mechanical)In this study, we derive reaction-diffusion equations for dislocation patterning of dislocation cell structures and subgrains. In order to express the generation of dislocation pattern responding to deformation progress, information of slip rate and stress and effect of interactions between slip systems on formation of cell structures are introduced into the reaction rate coefficients of reaction-diffusion equations. Moreover, we propose a multiscale crystal plasticity model based on dislocation patterning. Then we carry out pseudo-three-dimensional FE-FD hybrid simulation for severe compression of FCC polycrystal using the present model. Some processes of ultra fine-graining, i.e., generation of dislocation cell structures, subgrains, dense dislocation walls and lamella subdivisions with high angle boundaries are numerically reproduced, and we investigate the effect of dislocation behavior on the processes of ultrafine-graining.
