Motomichi Koyama

J-GLOBAL         Last updated: Oct 9, 2019 at 20:54
 
Avatar
Name
Motomichi Koyama
Affiliation
Tohoku University
Research funding number
20722705
ORCID ID
https://orcid.org/0000-0002-5006-9976

Research Areas

 
 

Published Papers

 
Alireza Karimi, Reza Razaghi, Motomichi Koyama
Computer Methods and Programs in Biomedicine   182    Dec 2019
© 2019 The spontaneous coronary artery dissection (SCAD) is a clinical complication of angioplasty leading to an initiation of a tear/crack in the intima layer of the artery. The crack can propagate to the interface of the intima-media layer follo...
Samsol Faizal Anis, Motomichi Koyama, Shigeru Hamada, Hiroshi Noguchi
Theoretical and Applied Fracture Mechanics   104    Dec 2019
© 2019 Elsevier Ltd In this study, the effects of Mg on the fatigue crack growth (FCG) characteristics of precipitation-hardened Al6061 alloys containing Zr and excess Mg are examined. The growth behavior of microstructurally large cracks is inves...
Transformation-assisted hydrogen desorption during deformation in steels: Examples of αʹ- and ε-martensite
T. Hojo, M. Koyama, N. Terao, K. Tsuzaki, E. Akiyama
International Journal of Hydrogen Energy   In press    Dec 2019   [Refereed]
EBSD- and ECCI-based assessments of inhomogeneous plastic strain evolution coupled with digital image correlation
R. Kakimoto, M. Koyama, K. Tsuzaki
ISIJ International   In press    Dec 2019   [Refereed]
Growth behavior of a mechanically long fatigue crack in an FeCrNiMnCo high entropy alloy: A comparison with an austenitic stainless steel
Motomichi Koyama
ISIJ International   In press    Dec 2019   [Refereed]
B. Li, M. Koyama, S. Hamada, H. Noguchi
Theoretical and Applied Fracture Mechanics   In press    Dec 2019   [Refereed]
K. Habib, M. Koyama, T. Tsuchiyama, H. Noguchi
In press    Dec 2019   [Refereed]
Evolution of quasi-brittle hydrogen-assisted damages in a dual-phase steel
T. Kumamoto, M. Koyama, K. Sato, K. Tsuzaki
Materials Transactions   In pess    Dec 2019   [Refereed]
Akira Maenosono, Motomichi Koyama, Yoshihisa Tanaka, Shien Ri, Qinghua Wang, Hiroshi Noguchi
International Journal of Fatigue   128    Nov 2019   [Refereed]
© 2019 Elsevier Ltd We investigated the microstructurally small fatigue crack growth (FCG) in a fully laminated Ti-6Al-4V alloy. Basal slip only causes Mode II FCG, which is the predominant FCG mechanism in the present alloy. However, when the bas...
Motomichi Koyama, Daisuke Yamasaki, Arisa Ikeda, Tomohiko Hojo, Eiji Akiyama, Kenichi Takai, Kaneaki Tsuzaki
International Journal of Hydrogen Energy   44 26028-26035   Oct 2019
© 2019 Hydrogen Energy Publications LLC The effects of martensitic transformation on microstructural hydrogen distribution in a multiphase transformation-induced plasticity (TRIP) steel were investigated using silver decoration before and after co...
Akinobu Shibata, Masanori Enoki, Nahoko Saji, Hirotaka Tai, Motomichi Koyama, Hiroshi Ohtani, Nobuhiro Tsuji, Kaneaki Tsuzaki
Metallurgical and Materials Transactions A: Physical Metallurgy and Materials Science   50(9) 4027-4036   Sep 2019   [Refereed]
© 2019, The Minerals, Metals & Materials Society and ASM International. This study investigated the effect of hydrogen on the substructure of martensite in Fe-31Ni alloy. In both the hydrogen-charged and uncharged specimens, typical lenticular m...
Motomichi Koyama, Natsuki Terao, Kaneaki Tsuzaki
Materials Letters   249 197-200   Aug 2019
© 2019 Elsevier B.V. Hydrogen effects on deformation-induced γ-ε martensitic transformation were revisited in terms of morphology, number density, and fraction of ε-martensite in strained austenitic steel. Hydrogen charging suppresses the stress-a...
Qinghua Wang, Shien Ri, Akira Maenosono, Yoshihisa Tanaka, Motomichi Koyama
Data in Brief   25    Aug 2019
© 2019 The Author(s) Dynamic microscale strain distributions with temporal resolution of 1 s in a smooth and a cracked Ti-6Al-4V alloys during one-cycle dwell fatigue tests are illustrated in videos (URL: https://drive.google.com/drive/folders/1pi...
Y. Kuroki, S. Kawano, S. Iikubo, H. Ohtani, M. Koyama, K. Tsuzaki
Metallurgical and Materials Transactions A: Physical Metallurgy and Materials Science   50 3019-3023   Jul 2019
© 2019, The Minerals, Metals & Materials Society and ASM International. This study uses first-principles calculations to investigate the effect of hydrogen on the chemical driving force of the transformation of iron from the face centered cubic ...
T. Kumamoto, M. Koyama, K. Sato, K. Tsuzaki
Engineering Fracture Mechanics   216    Jul 2019
© 2019 Elsevier Ltd Micro-damage quantification and associated microstructure characterization in a ferrite/martensite dual-phase (DP) steel were performed after tensile tests with different strain rates of 10−2 and 10−4 s−1 in order to understand...
Motomichi Koyama, Kenshiro Ichii, Kaneaki Tsuzaki
International Journal of Hydrogen Energy   44(31) 17163-17167   Jun 2019   [Refereed]
© 2019 Hydrogen Energy Publications LLC We investigated the grain refinement effect on the resistance to hydrogen embrittlement in an equiatomic CoCrFeMnNi high-entropy alloy. In a 100 MPa hydrogen gas pre-charging condition, grain refinement to 1...
Qinghua Wang, Shien Ri, Akira Maenosono, Yoshihisa Tanaka, Motomichi Koyama
Mechanics of Materials   133 63-70   Jun 2019   [Refereed]
© 2019 Towards clarifying underlying behavior of dwell fatigue in Ti alloys, we here present the first example of 1 second- and 1 μm-resolved full-field dynamic strain mapping. It has been realized by developing a video sampling moiré method comb...
Motomichi Koyama, Cemal Cem Tasan, Kaneaki Tsuzaki
Engineering Fracture Mechanics   214 123-133   Jun 2019   [Invited]
© 2019 Elsevier Ltd The main factors affecting resistance to hydrogen-assisted cracking are hydrogen diffusivity and local ductility. In this context, we note fcc (γ) to hcp (ε) martensitic transformation, instead of γ to bcc (ά) martensitic trans...
Tak Min Park, Min Tae Kim, Kyeong Ho Baik, Motomichi Koyama, Jeongho Han
Materials Characterization   151 221-226   May 2019   [Refereed]
© 2019 Elsevier Inc. We suggest that the partial recrystallization is a novel pathway to increase the hydrogen embrittlement resistance of Fe-Mn-C twinning-induced plasticity steels. The Fe-18Mn-0.6C (wt%) cold-rolled steel was annealed for from 3...
Zhao Zhang, Motomichi Koyama, Meimei Wang, Cemal Cem Tasan, Hiroshi Noguchi
Metallurgical and Materials Transactions A: Physical Metallurgy and Materials Science   50 1142-1145   Mar 2019
© 2019, The Minerals, Metals & Materials Society and ASM International. Pre-cold-rolling before annealing in transformation-induced plasticity (TRIP) maraging steels changes the microstructural morphology from lamellar to granular, increasing th...
Ibrahim Burkay Tuğluca, Motomichi Koyama, Yusaku Shimomura, Burak Bal, Demircan Canadinc, Eiji Akiyama, Kaneaki Tsuzaki
Metallurgical and Materials Transactions A: Physical Metallurgy and Materials Science   50 1137-1141   Mar 2019
© 2019, The Minerals, Metals & Materials Society and ASM International. We investigated the strain rate dependency of the hydrogen-induced mechanical degradation of Fe-33Mn-1.1C steel at 303 K within the strain rate range of 10 −2 to 10 −5 s −1...
Shunsuke Mizumachi, Motomichi Koyama, Yoshihiro Fukushima, Kaneaki Tsuzaki
Tetsu-To-Hagane/Journal of the Iron and Steel Institute of Japan   105 93-99   Feb 2019
© 2019 Iron and Steel Institute of Japan. All Rights Reserved. Synopsis: Fatigue crack growth characteristics of an Fe20Cr20Ni20Mn20Co high entropy alloy (HEA) were investigated by ΔK increasing compact tension test in comparison with a SUS316L. F...
Ryohei Kakimoto, Motomichi Koyama, Kaneaki Tsuzaki
Tetsu-To-Hagane/Journal of the Iron and Steel Institute of Japan   105 100-108   Feb 2019
© 2019 Iron and Steel Institute of Japan. All Rights Reserved. Synopsis: We measured local grain orientation gradient and dislocation density by electron backscatter diffraction (EBSD) measurement and electron channeling contrast imaging (ECCI) to...
Daisuke Sasaki, Motomichi Koyama, Hiroshi Noguchi
ISIJ International   59 1683-1690   Jan 2019
© 2019 ISIJ. In order to clarify influence of stress re-distribution effect on hydrogen-induced fatigue crack propagation, we investigated fatigue crack propagation rates and brittle-like fracture ratio. The experiments were conducted in nitrogen ...
Kishan Habib, Motomichi Koyama, Toshihiro Tsuchiyama, Hiroshi Noguchi
Metallurgical and Materials Transactions A: Physical Metallurgy and Materials Science   50 426-435   Jan 2019
© 2018, The Minerals, Metals & Materials Society and ASM International. We attempted to clarify the underlying mechanisms of the enhanced small-fatigue-crack resistance of Fe-Mn-C twinning-induced plasticity (TWIP) steel and high-nitrogen austen...
Tsubasa Kumamoto, Motomichi Koyama, Koichi Sato, Kaneaki Tsuzaki
Nippon Kinzoku Gakkaishi/Journal of the Japan Institute of Metals   83 221-230   Jan 2019
© 2019 Japan Institute of Metals (JIM). All rights reserved. We studied the statistical quantitative analysis of the hydrogen-assisted damage evolution behavior from nano- to micro-scale by combining positron annihilation spectroscopy(PAS)and scan...
B. Cameron, Motomichi Koyama, C.C. Tasan
Metallurgical Materials Transctions A   50(1) 29-34   Jan 2019   [Refereed]
K. Habib, Motomichi Koyama, E. Sakurada, N. Yoshimura, T. Yokoi, K. Ushioda, Kaneaki Tsuzaki
ISIJ International   59(1) 186-191   2019   [Refereed]
Fatigue resistance of metastable laminated microstructures
M. Koyama, H. Noguchi, K. Tsuzaki
Materia   58 206-213   2019   [Refereed][Invited]
X.Lin, M. Koyama, S.Gao, N. Tsuiji, K. Tsuzaki
International Journal of Fatigue   118 117-125   2019   [Refereed]
Motomichi Koyama, Kenji Hirata, Yuji Abe, Akihiro Mitsuda, Satoshi Iikubo, Kaneaki Tsuzaki
Scientific Reports   8    Dec 2018
© 2018, The Author(s). Iron and steels are extensively used as structural materials, and have three primary phase structures: Body-centered cubic (bcc), face-centered cubic (fcc), and hexagonal closed-packed (hcp). Controlling phase stabilities, e...
Wang Qinghua, Ri Shien, Tsuda Hiroshi, Koyama Motomichi
OPTICS AND LASERS IN ENGINEERING   110 155-162   Nov 2018   [Refereed]
Effect of shear-affected zone on fatigue crack propagation mode
Shigeru Hamada, Kejin Zhang, Jiwang Zhang, Motomichi Koyama, Tatsuo Yokoi, Hiroshi Noguchi
International Journal of Fatigue   116 36-47   Nov 2018   [Refereed]
Roughness-induced stress shielding effect in fatigue crack propagation under Mode II loading
Shigeru Hamada, Taro Suemasu, Shuto Fukudome, Motomichi Koyama, Masaharu Ueda, Hiroshi Noguchi
International Journal of Fatigue   116 245-256   Nov 2018   [Refereed]
Takuro Ogawa, Motomichi Koyama, Yuri Nishikura, Kaneaki Tsuzaki, Hiroshi Noguchi
ISIJ International   58 1910-1919   Oct 2018
© 2018 ISIJ Fatigue properties of Fe-19Cr-8Ni-0.05C and Fe-19Cr-8Ni-0.14C steels were investigated using a rotating bending fatigue test machine. Fatigue limit of both of the steels were dominated by critical stress amplitude for crack initiation....
K. Hirata, S. Iikubo, M. Koyama, K. Tsuzaki, H. Ohtani
Metallurgical and Materials Transactions A: Physical Metallurgy and Materials Science   49 5015-5022   Oct 2018
© 2018, The Minerals, Metals & Materials Society and ASM International. The hydrogen diffusion behavior in BCC, FCC, and HCP iron has been investigated by means of first-principles calculations. Diffusion coefficients were estimated quantitative...
Koyama Motomichi, Yamasaki Daisuke, Tsuzaki Kaneaki
MATERIALS LETTERS   228 273-276   Oct 2018   [Refereed]
Hamada Shigeru, Zhang Jiwang, Zhang Kejin, Koyama Motomichi, Tsuchiyama Toshihiro, Yokoi Tatsuo, Noguchi Hiroshi
INTERNATIONAL JOURNAL OF FRACTURE   212(2) 237-248   Aug 2018   [Refereed]
Nishikura Yuri, Koyama Motomichi, Yamamura Yusuke, Ogawa Takuro, Tsuzaki Kaneaki, Noguchi Hiroshi
INTERNATIONAL JOURNAL OF FATIGUE   113 359-366   Aug 2018   [Refereed]
Yoshimura Nobuyuki, Ushioda Kohsaku, Yoshida Yuichi, Sakurada Eisaku, Yonemura Mitsuharu, Koyama Motomichi, Noguchi Hiroshi, Watanabe Chihiro
MATERIALS SCIENCE AND ENGINEERING A-STRUCTURAL MATERIALS PROPERTIES MICROSTRUCTURE AND PROCESSING   732 212-219   Aug 2018   [Refereed]
B. Bal, M. Koyama, D. Canadinc, G. Gerstein, H. J. Maier, K. Tsuzaki
Journal of Engineering Materials and Technology, Transactions of the ASME   140    Jul 2018
Copyright © 2018 by ASME. This paper presents a combined experimental and theoretical analysis focusing on the individual roles of microdeformation mechanisms that are simultaneously active during the deformation of twinning-induced plasticity (TW...
Ichii Kenshiro, Koyama Motomichi, Tasan Cemal Cem, Tsuzaki Kaneaki
SCRIPTA MATERIALIA   150 74-77   Jun 2018   [Refereed]
Li Bochuan, Koyama Motomichi, Sakurada Eisaku, Yoshimura Nobuyuki, Ushioda Kohsaku, Noguchi Hiroshi
INTERNATIONAL JOURNAL OF FATIGUE   110 1-9   May 2018   [Refereed]
Koyama Motomichi, Yamamura Yusuke, Sawaguchi Takahiro, Tsuzaki Kaneaki, Noguchi Hiroshi
INTERNATIONAL JOURNAL OF FATIGUE   108 18-24   Mar 2018   [Refereed]
M. Koyama, Y. Tanaka, K. Tsuzaki
Experimental Mechanics   58 381-386   Feb 2018
© 2017, Society for Experimental Mechanics. This study presents a microlithography-based approach to increase the spatial resolution of strain mapping by micrographic digital image correlation. A micro-mesh with a lattice size of 500 nm was added ...
Tugluca Ibrahim Burkay, Koyama Motomichi, Bal Burak, Canadinc Demircan, Akiyama Eiji, Tsuzaki Kaneaki
MATERIALS SCIENCE AND ENGINEERING A-STRUCTURAL MATERIALS PROPERTIES MICROSTRUCTURE AND PROCESSING   717 78-84   Feb 2018   [Refereed]
Kishan Habib, Motomichi Koyama, Toshihiro Tsuchiyama, Hiroshi Noguchi
Materials Research Letters   6 61-66   Jan 2018
© 2017 The Author(s). The dislocation pattern at the tip of a non-propagating fatigue crack in an Fe-25Cr-1N steel (mass%) was characterized by electron channeling contrast imaging. Planar dislocation arrays on two different slip planes were obser...
Nao Uehata, Motomichi Koyama, Shusaku Takagi, Kaneaki Tsuzaki
ISIJ International   58 179-185   Jan 2018
© 2018 ISIJ. We evaluated the availability of an optical-microscopy-based damage quantification method in a ferrite/ martensite dual-phase steel, and interpreted the obtained results toward screening damage evolution behavior under various test co...
Akira Maenosono, Motomichi Koyama, Yoshihisa Tanaka, Shien Ri, Qinghu Wang, Hiroshi Noguchi
Procedia Structural Integrity   13 694-699   Jan 2018
© 2018 The Authors. The fatigue life of Ti-6Al-4V alloy exhibits significant scatter, which is derived from the statistical scatter of uncontrollable material factors. In particular, crack propagation behaviors in microstructurally small cracks s...
Shigeru Hamada, Taro Suemasu, Motomichi Koyama, Masaharu Ueda, Hiroshi Noguchi
Procedia Structural Integrity   13 1026-1031   Jan 2018
© 2018 The Authors. The essence of rolling contact fatigue is the so-called "Mode II fatigue crack propagation." However, its understanding has not progressed as much as that of Mode I. We think that this cause is the name: "Mode II fatigue crack ...
Kejin Zhang, Shigeru Hamada, Motomichi Koyama, Tatsuo Yokoi, Hiroshi Noguchi
Procedia Structural Integrity   13 1047-1052   Jan 2018
© 2018 The Authors. In punched steel plate, "punched specimen" from here onwards, the region near the edge of the punched hole is called the shear-affected-zone (SAZ), where tensile characteristics are compromised due to the punching process. Howe...
Mohammadi Abbas, Koyama Motomichi, Gerstein Gregory, Maier Hans Juergen, Noguchi Hiroshi
INTERNATIONAL JOURNAL OF HYDROGEN ENERGY   43(4) 2492-2502   Jan 2018   [Refereed]
Motomichi Koyama T. Kaneko, T. Sawaguchi, K. Tsuzaki
International Journal of Fracture   213(2) 193-206   2018   [Refereed]
Koyama Motomichi, Abe Yuji, Tsuzaki Kaneaki
ISIJ INTERNATIONAL   58(9) 1745-1747   2018   [Refereed]
Koyama Motomichi, Sawaguchi Takahiro, Tsuzaki Kaneaki
ISIJ INTERNATIONAL   58(8) 1383-1395   2018   [Refereed]
Chiba Aya, Koyama Motomichi, Akiyama Eiji, Nishimura Toshiyasu
JOURNAL OF THE ELECTROCHEMICAL SOCIETY   165(2) C19-C26   2018   [Refereed]
On the unity of crystal plasticity modeling to uncover the individual roles of micro-deformation mechanisms on the work hardening response of Fe-23Mn-0.5C TWIP steel in the presence of hydrogen.
B. Bal, Motomichi Koyama, D. Canadinc, G. Gerstein, H.J. Maier, Kaneaki Tsuzaki
Journal of Engineering Materials and Technology   140 31002-31015   2018   [Refereed]
Z. Zang, Motomichi Koyama, M.M.Wang, Kaneaki Tsuzaki
International Journal of Fatigue   113 126-136   2018   [Refereed]
Cooling and deformation-induced hydrogen desorption in metastable austenitic steels detected by mass spectroscopy.
Motomichi Koyama, N. Terao, T. Hojo, E.Akiyama, Kaneaki Tsuzaki
Conference proceedings   J03    2018   [Refereed]
A new design concept for prevention of hydrogen-induced mechanical degradation: viewpoints of metastability and high entropy.
Motomichi Koyama, T Eguchi, K. Ichii, Kaneaki Tsuzaki
Structural Integrity Procedia      2018   [Refereed]
Effect of Si on temperature dependence of non-propagation limit of small fatigue crack in a Fe-C alloy.
K. Kishida, Motomichi Koyama, N. Yoshimura, E. Sakurada, T. Yokoi, K. Ushioda, Kaneaki Tsuzaki, H. Noguchi
Structural Integrity Procedia      2018   [Refereed]
Proposal of fractographic analysis method coupled with EBSD and ECCI.
T. Kaida, Motomichi Koyama, S. Hamada, H. Noguchi, E. Sakurada, T. Yokoi, K. Ushioda
   2018   [Refereed]
Small fatigue crack growth in a high entropy alloy.
K. Suzuki, Motomichi Koyama, H. Suzuki
Structural Integrity Procedia      2018   [Refereed]
Localized plasticity and associated cracking in stable and metastable high-entropy alloys pre-charged with hydrogen.
K. Ichii, Motomichi Koyama, C.C. Tasan, Kaneaki Tsuzaki
Structural Integrity Procedia      2018   [Refereed]
Strain rate sensitivity of microstructural damage evolution in a dual-phase steel pre-charged with hydrogen.
T. Kumamoto, Motomichi Koyama, Kaneaki Tsuzaki
Structural Integrity Procedia      2018   [Refereed]
Fatigue crack growth behavior and associated microstructure in a metastable high-entropy alloy.
T. Eguchi, Motomichi Koyama, Y. Fukushima, C.C. Tasan, Kaneaki Tsuzaki
Structural Integrity Procedia      2018   [Refereed]
The influence of fracture surface contact in fatigue crack propagation of material having texture under Mode II loading.
T. Suemasu, Motomichi Koyama, S. Hamada, M. Ueda, H. Noguchi
Structural Integrity Porcedia      2018   [Refereed]
Quantification method for parameters affecting multi-scale roughness-induced fatigue crack closure.
T. Mizoguchi, Motomichi Koyama, H. Noguchi
Structural Integrity Procedia      2018   [Refereed]
Analysis of fatigue crack configuration influence on fatigue life.
M. Aibara, Motomichi Koyama, S. Hamada, H. Noguchi
Structural Integrity Procedia      2018   [Refereed]
Proposal and verification of novel fatigue crack propagation simulation method by finite element method.
T. Sano, Motomichi Koyama, D. Sasaki, H. Noguchi
Structural Integrity Procedia      2018   [Refereed]
Koyama Motomichi, Shimomura Yusaku, Chiba Aya, Akiyama Eiji, Tsuzaki Kaneaki
SCRIPTA MATERIALIA   141 20-23   Dec 2017   [Refereed]
Habib Kishan, Koyama Motomichi, Tsuchiyama Toshihiro, Noguchi Hiroshi
INTERNATIONAL JOURNAL OF FATIGUE   104 158-170   Nov 2017   [Refereed]
Ju Yun-Byum, Koyama Motomichi, Sawaguchi Takahiro, Tsuzaki Kaneaki, Noguchi Hiroshi
INTERNATIONAL JOURNAL OF FATIGUE   103 533-545   Oct 2017   [Refereed]
Koyama Motomichi, Ogawa Takuro, Yan Dingshun, Matsumoto Yuya, Tasan Cemal Cem, Takai Kenichi, Tsuzaki Kaneaki
INTERNATIONAL JOURNAL OF HYDROGEN ENERGY   42(42) 26423-26435   Oct 2017   [Refereed]
Li Bochuan, Koyama Motomichi, Hamada Shigeru, Noguchi Hiroshi
ENGINEERING FRACTURE MECHANICS   182 287-302   Sep 2017   [Refereed]
Micrographic Digital Image Correlation Coupled with Microlithography: Case Study of Strain Localization and Subsequent Cracking at an FIB Notch Tip in a Laminated Ti-6Al-4VAlloy
M. Koyama, Y. Tanaka, K. Tsuzaki
Experimental Mechanics   58 381-386   Sep 2017   [Refereed]
Fukumura Naoki, Li Bochuan, Koyama Motomichi, Suzuki Tomohiro, Hamada Shigeru, Tsuzaki Kaneaki, Noguchi Hiroshi
THEORETICAL AND APPLIED FRACTURE MECHANICS   90 193-202   Aug 2017   [Refereed]
Z. Zhang, M. Koyama, M. M. Wang, K. Tsuzaki, C. C. Tasan, H. Noguchi
International Journal of Fatigue   100 176-186   Jul 2017
© 2017 Elsevier Ltd The effect of austenitization time on the fatigue crack resistance of transformation-induced plasticity (TRIP)-maraging steel was investigated by observing the crack initiation site, propagation path and fracture surface. Our a...
Koyama Motomichi, Onishi Yosuke, Noguchi Hiroshi
INTERNATIONAL JOURNAL OF FRACTURE   206(1) 123-130   Jul 2017   [Refereed]
Ogawa Takuro, Koyama Motomichi, Tasan Cemal Cem, Tsuzaki Kaneaki, Noguchi Hiroshi
JOURNAL OF MATERIALS SCIENCE   52(13) 7868-7882   Jul 2017   [Refereed]
Yoshimura Nobuyuki, Ushioda Kohsaku, Yonemura Mitsuharu, Koyama Motomichi, Tanaka Masaki, Noguchi Hiroshi
MATERIALS SCIENCE AND ENGINEERING A-STRUCTURAL MATERIALS PROPERTIES MICROSTRUCTURE AND PROCESSING   701 120-128   Jul 2017   [Refereed]
Koyama Motomichi, Yamanouchi Keita, Wang Qinghua, Ri Shien, Tanaka Yoshihisa, Hamano Yasuaki, Yamasaki Shigeto, Mitsuhara Masatoshi, Ohkubo Masataka, Noguchi Hiroshi, Tsuzaki Kaneaki
MATERIALS CHARACTERIZATION   128 217-225   Jun 2017   [Refereed]
Habib Kishan, Koyama Motomichi, Noguchi Hiroshi
INTERNATIONAL JOURNAL OF FATIGUE   99 1-12   Jun 2017   [Refereed]
Wang Qinghua, Ri Shien, Tsuda Hiroshi, Koyama Motomichi, Tsuzaki Kaneaki
OPTICS EXPRESS   25(12) 13465-13480   Jun 2017   [Refereed]
Li Bochuan, Koyama Motomichi, Sakurada Eisaku, Yoshimura Nobuyuki, Ushioda Kohsaku, Noguchi Hiroshi
INTERNATIONAL JOURNAL OF FATIGUE   98 101-110   May 2017   [Refereed]
Koyama Motomichi, Akiyama Eiji, Lee Young-Kook, Raabe Dierk, Tsuzaki Kaneaki
INTERNATIONAL JOURNAL OF HYDROGEN ENERGY   42(17) 12706-12723   Apr 2017   [Refereed]
T. Nagashima, M. Koyama*, A. Bashir, M. Rohwerder, C. C. Tasan, E. Akiyama, D. Raabe and K. Tsuzaki
Materials and Corrosion 2017   68(3) 306-310   Mar 2017   [Refereed]
Koyama Motomichi, Yamasaki Daisuke, Nagashima Tatsuya, Tasan Cemal Cem, Tsuzaki Kaneaki
SCRIPTA MATERIALIA   129 48-51   Mar 2017   [Refereed]
Koyama Motomichi, Zhang Zhao, Wang Meimei, Ponge Dirk, Raabe Dierk, Tsuzaki Kaneaki, Noguchi Hiroshi, Tasan Cemal Cem
SCIENCE   355(6329) 1055-1057   Mar 2017   [Refereed]
Koyama Motomichi, Li Huichao, Hamano Yasuaki, Sawaguchi Takahiro, Tsuzaki Kaneaki, Noguchi Hiroshi
ENGINEERING FAILURE ANALYSIS   72 34-47   Feb 2017   [Refereed]
Omura Toshinobu, Koyama Motomichi, Hamano Yasuaki, Tsuzaki Kaneaki, Noguchi Hiroshi
INTERNATIONAL JOURNAL OF FATIGUE   95 38-44   Feb 2017   [Refereed]
Motomichi Koyama, Bohong Ren, Nobuyuki Yoshimura, Eisaku Sakurada, Kohsaku Ushioda, Hiroshi Noguchi
Tetsu-To-Hagane/Journal of the Iron and Steel Institute of Japan   103 660-666   Jan 2017
The coaxing effect has been recognized as a phenomenon that enhances the fatigue resistance associated with work hardening and strainage hardening. To uncover the intrinsic factors that affect the degree of coaxing effect, rotating bending fatigue...
S. F. Anis, M. Koyama, H. Noguchi
Materials Science Forum   889 MSF 143-147   Jan 2017
© 2017 Trans Tech Publications, Switzerland. The influence of excess Mg on the Mode I propagation of fatigue crack was examined in newly developed precipitation-hardened Al alloy containing Zr and excess Mg. The aim of this study was to evaluate t...
Q. Wang, S. Ri, Y. Tanaka, M. Koyama
ICCM International Conferences on Composite Materials   2017-August    Jan 2017
© 2017 International Committee on Composite Materials. All rights reserved. Owing to high tensile strength and toughness even at high temperatures, titanium (Ti) alloys hold great promise for applications in automobiles, aircraft, spacecraft, etc....
Motomichi Koyama, Takahiro Sawaguchi, Kaneaki Tsuzaki
ICF 2017 - 14th International Conference on Fracture   1 75-76   Jan 2017
© 2017 ICF 2017 - 14th International Conference on Fracture. All rights reserved. We used Fe-20Mn, Fe-28Mn, Fe-32Mn, and Fe-40Mn alloys. ε-martensite in the Fe-20Mn alloy critically deteriorated the resistance to hydrogen embrittlement owing to α'...
Q. H. Wang, S. Ri, Y. Tanaka, K. Naito, M. Koyama, K. Tsuzaki, M. Ohkubo
ICF 2017 - 14th International Conference on Fracture   2 481-482   Jan 2017
© 2017 Chinese Society of Theoretical and Applied Mechanics. All Rights Reserved. The full-field strain concentrations of a titanium (Ti) alloy were quantitatively and visually investigated for prediction of crack occurrence in a tensile test. The...
Koyama Motomichi, Yamamura Yusuke, Che Rinqing, Sawaguchi Takahiro, Tsuzaki Kaneaki, Noguchi Hiroshi
INTERNATIONAL JOURNAL OF FATIGUE   94 1-5   Jan 2017   [Refereed]
Koyama Motomichi, Rohwerder Michael, Tasan Cemal Cem, Bashir Asif, Akiyama Eiji, Takai Kenichi, Raabe Dierk, Tsuzaki Kaneaki
MATERIALS SCIENCE AND TECHNOLOGY   33(13) 1481-1496   2017   [Refereed]
Koyama Motomichi, Ren Bohong, Yoshimura Nobuyuki, Sakurada Eisaku, Ushioda Kohsaku, Noguchi Hiroshi
ISIJ INTERNATIONAL   57(2) 358-364   2017   [Refereed]

Conference Activities & Talks

 
Designing Hydrogen-Resistant Steels: Effects of Phase Stability, Configurational Entropy and Grain Refinement
Motomichi Koyama
Hydrogen-Metal System Gordon research conference (GRC)   Jun 2019   
Hydrogen embrittlement of advanced stable austenitic steels: examples of high-nitrogen steel and high-entropy alloy
Motomichi Koyama
International Conference “Corrosion in the Oil & Gas Industry”- Corrosion Oil&Gas 2019   May 2019   
Microstructure evolution beneath fatigue fracture surface
Motomichi Koyama
International Conference High-entropy materials (ICHEM)   Dec 2018   
A new concept for prevention of hydrogen-induced mechanical degradation: viewpoints of metastability and high entropy. [Invited]
Motomichi Koyama, T. Eguchi, K. Ichii, C.C. Tasan, Kaneaki Tsuzaki
European Conference on Fracture, Belgrade, Serbia   Aug 2018   
Microstructural factors enhancing fatigue crack resistance: aspects of metastability and nano-laminates. [Invited]
Motomichi Koyama
International Symposium on Innovative Process Design for Structural Materials, Seoul, Korea   25 Sep 2017   
Microstructural hydrogen detection and associated damage analysis in steels. [Invited]
Motomichi Koyama
Joint hydrogenious and i2cner international workshop on hydrogen-materials interactions 2017, Fukuoka, Japan   3 Feb 2017   
Effective utilization of ε-martensite in Fe-High Mn austenitic steels: aspects of deformation-induced reverse transformation. [Invited]
Motomichi Koyama
TMS 2016, Nashville Tennessee, USA   18 Feb 2016   
Multi-scale anyalysis on hydrogen-assisted damage evokution in fe-ni-c austenite/martensite dual phase steel. [Invited]
Motomichi Koyama
International Symposium on Plasticity and Its Current Applications 2016, Keauhou bay, Hawaii, USA   5 Jan 2016   
Advanced strategy of multi-scale damage evolution analysis and hydrogen mapping in complex steels. [Invited]
Motomichi Koyama
Max-Planck-Institut fur Eisenforschung GmbH work shop Hydrogen Embrittlement and Sour Gas Corrosion, Dusseldorf, Gemany   27 Jan 2015   
Role of twin boundary on plasticity and embrittlement in high Mn austenitic steel. [Invited]
Motomichi Koyama
International Symposium on Plasticity and Its Current Applications 2015 Montego Bay, Jamaica   Jan 2015