東北大学 研究者紹介 - 小山　元道

Martensite Boundary Characteristics on Cycle- and Time-Dependent Fatigue Crack Growth Paths of Tempered Lath Martensitic Steels in a 90 MPa Gaseous Hydrogen Atmosphere 査読有り

Tingshu Chen, Motomichi Koyama, Yuhei Ogawa, Hisao Matsunaga, Eiji Akiyama

Metallurgical and Materials Transactions A: Physical Metallurgy and Materials Science　54　(7)　2512-2518　2023年7月

DOI： 10.1007/s11661-023-07041-9 　

ISSN：1073-5623

Cr Effects on the Local Plasticity Evolution and Fracture Behaviors of Ni–Cr Alloys Tensile-Tested under Hydrogen Charging 査読有り

Naohiro Kobayashi, Motomichi Koyama, Misaho Yamamura, Tomohiko Hojo, Eiji Akiyama

MATERIALS TRANSACTIONS　64　(1)　212-219　2023年1月1日

DOI： 10.2320/matertrans.mt-m2022140 　

ISSN：1345-9678

eISSN：1347-5320

Crack Tip Deformation during Dwell Fatigue and Its Correlation with Crack/Fracture Surface Morphologies in a Bi-Modal Ti–6Al–4V Alloy

Yuma Aoki, Motomichi Koyama, Masaki Tanaka, Kaneaki Tsuzaki

MATERIALS TRANSACTIONS　63　(9)　1232-1241　2022年9月1日

DOI： 10.2320/matertrans.mt-m2022076 　

ISSN：1345-9678

eISSN：1347-5320

Effects of Mn Content and Grain Size on Hydrogen Embrittlement Susceptibility of Face-Centered Cubic High-Entropy Alloys

Motomichi Koyama, Haoyu Wang, Virendra Kumar Verma, Kaneaki Tsuzaki, Eiji Akiyama

Metallurgical and Materials Transactions A: Physical Metallurgy and Materials Science　51　(11)　5612-5616　2020年11月1日

DOI： 10.1007/s11661-020-05966-z 　

ISSN：1073-5623

Hydrogen Enhances Shape Memory Effect of a Ferrous Face-Centered Cubic Alloy 査読有り

Motomichi Koyama, Chunxi Hao, Eiji Akiyama, Kaneaki Tsuzaki

Metallurgical and Materials Transactions A: Physical Metallurgy and Materials Science　51　(9)　4439-4441　2020年9月1日

DOI： 10.1007/s11661-020-05886-y 　

ISSN：1073-5623

Origin of micrometer-scale dislocation motion during hydrogen desorption

Motomichi Koyama, Seyedeh Mohadeseh Taheri-Mousavi, Seyedeh Mohadeseh Taheri-Mousavi, Haoxue Yan, Jinwoo Kim, Benjamin Clive Cameron, Seyed Sina Moeini-Ardakani, Ju Li, Ju Li, Cemal Cem Tasan

Science Advances　6　(23)　2020年6月

DOI： 10.1126/sciadv.aaz1187 　

eISSN：2375-2548

Gaseous hydrogen embrittlement of a Ni-free austenitic stainless steel containing 1 mass% nitrogen: Effects of nitrogen-enhanced dislocation planarity 査読有り

Motomichi Koyama, Kishan Habib, Takuro Masumura, Toshihiro Tsuchiyama, Hiroshi Noguchi

International Journal of Hydrogen Energy　45　(16)　10209-10218　2020年3月20日

DOI： 10.1016/j.ijhydene.2020.02.014 　

ISSN：0360-3199

Dislocation motion at a fatigue crack tip in a high-nitrogen steel clarified through in situ electron channeling contrast imaging 査読有り

Kishan Habib, Motomichi Koyama, Toshihiro Tsuchiyama, Hiroshi Noguchi

Materials Characterization　158　2019年12月

DOI： 10.1016/j.matchar.2019.109930 　

ISSN：1044-5803

Crystallographic selection rule for the propagation mode of microstructurally small fatigue crack in a laminated Ti-6Al-4V alloy: Roles of basal and pyramidal slips 査読有り

Akira Maenosono, Motomichi Koyama, Yoshihisa Tanaka, Shien Ri, Qinghua Wang, Hiroshi Noguchi

International Journal of Fatigue　128　105200-105200　2019年11月1日

DOI： 10.1016/j.ijfatigue.2019.105200 　

ISSN：0142-1123

Revisiting the effects of hydrogen on deformation-induced γ-ε martensitic transformation

Motomichi Koyama, Natsuki Terao, Kaneaki Tsuzaki

Materials Letters　249　197-200　2019年8月15日

DOI： 10.1016/j.matlet.2019.04.093 　

ISSN：0167-577X

eISSN：1873-4979

Grain refinement effect on hydrogen embrittlement resistance of an equiatomic CoCrFeMnNi high-entropy alloy 査読有り

Motomichi Koyama, Kenshiro Ichii, Kaneaki Tsuzaki

International Journal of Hydrogen Energy　44　(31)　17163-17167　2019年6月21日

DOI： 10.1016/j.ijhydene.2019.04.280 　

ISSN：0360-3199

Fatigue Resistance of Laminated and Non-laminated TRIP-maraging Steels: Crack Roughness vs Tensile Strength

Zhao Zhang, Motomichi Koyama, Meimei Wang, Cemal Cem Tasan, Hiroshi Noguchi

Metallurgical and Materials Transactions A: Physical Metallurgy and Materials Science　50　1142-1145　2019年3月15日

DOI： 10.1007/s11661-018-5081-6 　

ISSN：1073-5623

An unconventional hydrogen effect that suppresses thermal formation of the hcp phase in fcc steels

Motomichi Koyama, Kenji Hirata, Yuji Abe, Akihiro Mitsuda, Satoshi Iikubo, Kaneaki Tsuzaki

Scientific Reports　8　2018年12月1日

DOI： 10.1038/s41598-018-34542-0 　

Bone-like crack resistance in hierarchical metastable nanolaminate steels 査読有り

Motomichi Koyama, Zhao Zhang, Meimei Wang, Dirk Ponge, Dierk Raabe, Kaneaki Tsuzaki, Hiroshi Noguchi, Cemal Cem Tasan

SCIENCE　355　(6329)　1055-1057　2017年3月

DOI： 10.1126/science.aal2766 　

ISSN：0036-8075

eISSN：1095-9203

Surface and Internal Crack Growth during Tensile Loading in Ni-free High-nitrogen Austenitic Steel 査読有り

Motomichi Koyama, Yongxin Wang, Rama Srinivas Varanasi, Takuro Masumura, Toshihiro Tsuchiyama

ISIJ International　66　(4)　460-470　2026年3月30日

DOI： 10.2355/isijinternational.isijint-2025-212 　

ISSN：0915-1559

eISSN：1347-5460

Hydrogen Embrittlement of Hole-Expanded TRIP-aided Martensitic Steel Sheet 査読有り

Zisong Guo, Tomohiko Hojo, Hiroyuki Saitoh, Ayumi Shiro, Takahisa Shobu, Ryo Yasuda, Saya Ajito, Motomichi Koyama, Eiji Akiyama, Fumio Yuse, Makoto Kawamori

ISIJ International　66　(4)　590-598　2026年3月30日

DOI： 10.2355/isijinternational.isijint-2024-381 　

ISSN：0915-1559

eISSN：1347-5460

Neutron Diffraction Analysis of Dislocation Behaviour and Substructures of Si-alloyed and Interstitial-free BCC Steels 査読有り

Masayoshi Kumagai, Takanori Ito, Sunao Sadamatsu, Gábor Ribárik, Tamás Ungár, Motomichi Koyama

ISIJ International　66　(4)　471-476　2026年3月30日

DOI： 10.2355/isijinternational.isijint-2025-290 　

ISSN：0915-1559

eISSN：1347-5460

Localized plasticity, transformation, and martensite cracking in hydrogen-charged metastable austenitic stainless steel studied by in situ electron channeling contrast imaging 査読有り

Motomichi Koyama, Zhipeng Yang, Wenwu Xu, Eiji Akiyama

Materials Characterization　233　116127-116127　2026年3月

DOI： 10.1016/j.matchar.2026.116127 　

ISSN：1044-5803

Microscopic Strain Mapping: Functional Diversity and Their Demands 招待有り 査読有り

Motomichi Koyama, Kazuyuki Shimizu, Shien Ri, Norimitsu Koga, Hideaki Nishikawa, Tatsuya Morikawa, Hiroshi Fudouzi

MATERIALS TRANSACTIONS　67　(2)　99-116　2026年2月1日

DOI： 10.2320/matertrans.mt-m2025128 　

ISSN：1345-9678

eISSN：1347-5320

Hydrogen embrittlement in a CoCrNi medium-entropy alloy fabricated via laser powder bed fusion: Characteristic intergranular cracking and hydrogen-enhanced twinning 査読有り

Tingshu Chen, Hang Su, Motomichi Koyama, Hong Luo, Sui Wang, Zihan Chen, Anqing Fu, Yanan Li, Yao Zhang

Journal of Materials Science & Technology　240　201-213　2026年1月

DOI： 10.1016/j.jmst.2025.03.048 　

ISSN：1005-0302

In situ hydrogen embrittlement behavior of Fe-based medium entropy alloys with varying microstructures 査読有り

Young Kyun Kim, Jae Ho Lee, Duk Hyun Chung, Seong June Youn, Seok Su Sohn, Motomichi Koyama, Young Sang Na

International Journal of Hydrogen Energy　202　153077-153077　2026年1月

DOI： 10.1016/j.ijhydene.2025.153077 　

ISSN：0360-3199

Strengthening mechanism in ferrite and austenite of friction stir welded duplex stainless steel: In situ neutron diffraction study

Takayuki Yamashita, Motomichi Koyama, Wu Gong, Takuro Kawasaki, Stefanus Harjo, Kohsaku Ushioda, Hidetoshi Fujii

ISIJ International　2026年

DOI： 10.2355/isijinternational.isijint-2025-291 　

ISSN：0915-1559

eISSN：1347-5460

4D analysis of damage mechanisms in ductile fracture of quenched and tempered DP steels using synchrotron X-ray microtomography

Kazuyuki Shimizu, Hibiki Ishida, Yasuhiro Kamada, Tomohiko Hojo, Motomichi Koyama, Masayuki Uesugi, Akihisa Takeuchi, Takashi Matsuno

ISIJ International　2026年

DOI： 10.2355/isijinternational.isijint-2025-285 　

ISSN：0915-1559

eISSN：1347-5460

Revealing strength-ductility synergy in TRIP-assisted lean duplex stainless steels: The critical role of strain-induced martensitic transformation kinetics in damage tolerance and fracture mechanism 査読有り

Yongxin Wang, Xingzhou Cai, Rama Srinivas Varanasi, Zhenting Wang, Miao Jin, Huagui Huang, Xiaocong Ma, Lei Chen, Motomichi Koyama

Materials Science and Engineering: A　945　149039-149039　2025年11月

DOI： 10.1016/j.msea.2025.149039 　

ISSN：0921-5093

In situ 2D visualization of hydrogen entry into Zn-coated steels in NaCl solutions: Roles of Zn dissolution and potential distribution

Hiroshi Kakinuma, Saya Ajito, Koki Okumura, Makoto Akahoshi, Yu Takabatake, Tomohiko Omura, Motomichi Koyama, Eiji Akiyama

Corrosion Science　113386-113386　2025年10月

DOI： 10.1016/j.corsci.2025.113386 　

ISSN：0010-938X

Strain rate dependency of hydrogen embrittlement resistance in an additively manufactured equiatomic CoCrFeNi high-entropy alloy 査読有り

Virendra Kumar Verma, Motomichi Koyama, Mehmet Cagirici, Siyuan Wei, Eiji Akiyama, Pei Wang, Upadrasta Ramamurty

International Journal of Hydrogen Energy　172　151340-151340　2025年9月

DOI： 10.1016/j.ijhydene.2025.151340 　

ISSN：0360-3199

Review—Polyaniline-Based Hydrogenochromic Sensor and Its Application for Visualizing Hydrogen Entry into Metals and Microstructure-Dependent Hydrogen Diffusion

Hiroshi Kakinuma, Saya Ajito, Motomichi Koyama, Eiji Akiyama

MATERIALS TRANSACTIONS　66　(9)　1095-1106　2025年9月1日

DOI： 10.2320/matertrans.mt-maw2025001 　

ISSN：1345-9678

eISSN：1347-5320

Factors controlling transformation-induced hydrogen desorption and hydrogen-reduced transformability in austenitic steels clarified via dynamic hydrogen detection during cryogenic deformation 査読有り

Motomichi Koyama, Yifei Wen, Tomohiko Hojo, Saya Ajito, Makoto Kawamori, Eiji Akiyama

Scripta Materialia　265　116749-116749　2025年8月

DOI： 10.1016/j.scriptamat.2025.116749 　

ISSN：1359-6462

An irreversible hydrogenochromic sensor applicable to corrosion environments with high sensitivity and high spatial resolution

Zhenting Wang, Saya Ajito, Yongxin Wang, Motomichi Koyama, Eiji Akiyama, Hiroshi Kakinuma

npj Materials Degradation　9　(1)　2025年7月1日

DOI： 10.1038/s41529-025-00630-6 　

eISSN：2397-2106

Analysis of Void Formation and Crack Propagation at Grain Boundaries in Al-Zn-Mg-Cu Alloy

Shota Tsuchiya, Kazuyuki Shimizu, Yasuhiro Kamada, Hiroyuki Toda, Hiro Fujihara, Kyosuke Hirayama, Motomichi Koyama, Masayuki Uesugi, Akihisa Takeuchi

MATERIALS TRANSACTIONS　66　(7)　895-902　2025年7月1日

DOI： 10.2320/matertrans.mt-l2025004 　

ISSN：1345-9678

eISSN：1347-5320

Overview of Hydrogen Effects on γ−ε Martensitic Transformation in Steels 招待有り 査読有り

Motomichi Koyama, Satoshi Iikubo, Rama Srinivas Varanasi

Tetsu-to-Hagane　111　(8)　379-390　2025年6月1日

DOI： 10.2355/tetsutohagane.tetsu-2025-007 　

ISSN：0021-1575

eISSN：1883-2954

Stability of electrochemical hydrogen charging in NaCl aqueous solution containing NH<inf>4</inf>SCN: Effect of changes in solution chemistry

Saya Ajito, Yusuke Kabasawa, Hiroshi Kakinuma, Motomichi Koyama, Eiji Akiyama

Corrosion Science　249　2025年6月

DOI： 10.1016/j.corsci.2025.112843 　

ISSN：0010-938X

Growth path and morphology of hydrogen-related cracks in grain-refined tempered martensitic steel produced by cyclic thermal treatment 査読有り

Tingshu Chen, Yuhei Ogawa, Motomichi Koyama

International Journal of Hydrogen Energy　136　731-741　2025年6月

DOI： 10.1016/j.ijhydene.2024.05.327 　

ISSN：0360-3199

Hydrogen Effects on Hall–Petch Coefficient and Fracture Strength in Pure Ni and Ni-20Cr Alloy: A Macroscopic Insight of the Hydrogen Embrittlement Mechanism

Motomichi Koyama, Kota Tomatsu, Hiroshi Kakinuma, Saya Ajito, Eiji Akiyama

Metallurgical and Materials Transactions A: Physical Metallurgy and Materials Science　56　(3)　771-777　2025年3月

DOI： 10.1007/s11661-025-07688-6 　

ISSN：1073-5623

eISSN：1543-1940

Semi-quantitative characterisation of coherency-dependent hydrogen diffusion at Σ3 grain boundaries in pure Ni

Hiroshi Kakinuma, Motomichi Koyama, Rama Srinivas Varanasi, Saya Ajito, Eiji Akiyama

Materials Research Letters　1-8　2025年1月24日

DOI： 10.1080/21663831.2025.2457369 　

eISSN：2166-3831

Grain boundary nanochemistry and intergranular corrosion of Fe-0.01wt.%P alloy: Roles of elemental segregations and misorientation

Saya Ajito, Kazuya Tojima, Hiroshi Kakinuma, Kohei Ikeda, Yongjie Zhang, Tomohiko Hojo, Goro Miyamoto, Motomichi Koyama, Tadashi Furuhara, Eiji Akiyama

Acta Materialia　283　120577-120577　2025年1月15日

DOI： 10.1016/j.actamat.2024.120577 　

ISSN：1359-6454

Prussian blue as a fully reversible hydrogenochromic material for visualizing hydrogen distribution in Fe sheet

Hiroshi Kakinuma, Yoshinori Sasaki, Saya Ajito, Motomichi Koyama, Eiji Akiyama

ISIJ International　2025年

DOI： 10.2355/isijinternational.isijint-2025-340 　

ISSN：0915-1559

eISSN：1347-5460

Analysis of void formation and crack propagation at grain boundaries in Al-Zn-Mg-Cu alloy

Shota Tsuchiya, Kazuyuki Shimizu, Yasuhiro Kamada, Hiroyuki Toda, Hiro Fujihara, Kyosuke Hirayama, Motomichi Koyama, Masayuki Uesugi, Akihisa Takeuchi

Keikinzoku/Journal of Japan Institute of Light Metals　75　(2)　96-102　2025年

DOI： 10.2464/jilm.75.96 　

ISSN：0451-5994

Positive strain rate dependence: optimizing TRIP effect for high-speed deformation in lean duplex stainless steel

Yongxin Wang, Lei Chen, Xingzhou Cai, Motomichi Koyama, Zhenting Wang, Xiaolong Li, Zhikun Bai, Xiaocong Ma, Miao Jin

Materials Research Letters　13　(1)　42-50　2025年

DOI： 10.1080/21663831.2024.2415903 　

eISSN：2166-3831

Stress and Plastic Strain Partitioning Behaviors and Those Contributions to Martensitic Transformation of Retained Austenite in Medium Manganese and Transformation-Induced Plasticity-Aided Bainitic Ferrite Steels

Tomohiko Hojo, Motomichi Koyama, Bakuya Kumai, Yutao Zhou, Yuki Shibayama, Ayumi Shiro, Takahisa Shobu, Hiroyuki Saitoh, Saya Ajito, Eiji Akiyama

ISIJ International　65　(2)　284-296　2025年

DOI： 10.2355/isijinternational.ISIJINT-2024-268 　

ISSN：0915-1559

Local Work-Hardening and Lüders Deformation Invariance in TRIP-Aided Medium-Mn High-Strength Steel: Significant TRIP Effect Changes in the Warm Temperature Range up to 200 ℃

Takashi MATSUNO, Yuta YAMAZAKI, Seiya MATSUBARA, Jin EGUCHI, Kazuyuki SHIMIZU, Motomichi KOYAMA, Yoshitaka OKITSU, Toshihiro TSUCHIYAMA

Journal of the Japan Society for Technology of Plasticity　66　(771)　61-68　2025年

DOI： 10.9773/sosei.240702 　

ISSN：0038-1586

eISSN：1882-0166

Microscopic Strain Mapping: Functional Diversity and Their Demands

Motomichi Koyama, Kazuyuki Shimizu, Shien Ri, Norimitsu Koga, Hideaki Nishikawa, Tatsuya Morikawa, Hiroshi Fudouzi

Journal of the Japan Institute of Metals and Materials　88　(11)　253-269　2024年11月1日

DOI： 10.2320/jinstmet.j202408 　

ISSN：0021-4876

eISSN：1880-6880 2433-7501

Stress-controlled hydrogen embrittlement failure in U-bend high-strength steel

Yuki Shibayama, Tomohiko Hojo, Motomichi Koyama, Eiji Akiyama

International Journal of Hydrogen Energy　88　1010-1016　2024年10月28日

DOI： 10.1016/j.ijhydene.2024.09.123 　

ISSN：0360-3199

Novel Fe-Mo intermetallic composite synthesized via diffusional-displacive mixed-mode transformation

Rama Srinivas Varanasi, Srikakulapu Kiranbabu, Reina Utsumi, Hiroyuki Saitoh, Ronald Schnitzer, Eiji Akiyama, Motomichi Koyama

Materials Characterization　216　2024年10月

DOI： 10.1016/j.matchar.2024.114287 　

ISSN：1044-5803

Visualization of Microscopic Hydrogen Diffusion in Polycrystalline Pure Ni Using an Ir Complex

Saya Ajito, Hiroshi Kakinuma, Motomichi Koyama, Eiji Akiyama

Zairyo-to-Kankyo　73　(8)　194-199　2024年8月10日

DOI： 10.3323/jcorr.73.194 　

ISSN：0917-0480

eISSN：1881-9664

Understanding crack growth within the γ′ Fe4N layer in a nitrided low carbon steel during monotonic and cyclic tensile testing 査読有り

Rama Srinivas Varanasi, Motomichi Koyama, Mizuho Yokoi, Yusuke Ootani, Momoji Kubo, Kento Tanahara, Osamu Umezawa

Journal of Materials Science　59　(31)　14639-14652　2024年7月28日

DOI： 10.1007/s10853-024-10014-x 　

ISSN：0022-2461

eISSN：1573-4803

ポリアニリンを用いた金属中を拡散する水素の可視化技術 招待有り 査読有り

Hiroshi Kakinuma, Saya Ajito, Motomichi Koyama, Eiji Akiyama

Materia Japan　63　(6)　381-389　2024年6月1日

DOI： 10.2320/materia.63.381 　

ISSN：1340-2625

eISSN：1884-5843

Hydrogen Embrittlement as a Conspicuous Material Challenge─Comprehensive Review and Future Directions

Haiyang Yu, Andrés Díaz, Xu Lu, Binhan Sun, Yu Ding, Motomichi Koyama, Jianying He, Xiao Zhou, Abdelali Oudriss, Xavier Feaugas, Zhiliang Zhang

Chemical Reviews　124　(10)　6271-6392　2024年5月22日

DOI： 10.1021/acs.chemrev.3c00624 　

ISSN：0009-2665

eISSN：1520-6890

Influence of austenite grain boundary misorientation on hydrogen-induced intergranular crack propagation in a medium carbon martensitic steel 査読有り

Ji Hoon Kim, Goro Miyamoto, Akinobu Shibata, Tomohiko Hojo, Motomichi Koyama, Yongjie Zhang, Tadashi Furuhara

Acta Materialia　274　120036-120036　2024年5月

DOI： 10.1016/j.actamat.2024.120036 　

ISSN：1359-6454

Mechanism of local hydrogen entry into Fe sheets induced by atmospheric corrosion: Significance of potential, pH, and rust layer thickness 査読有り

Hiroshi Kakinuma, Sachiko Hiromoto, Tomohiko Hojo, Saya Ajito, Motomichi Koyama, Eiji Akiyama

Corrosion Science　232　112043-112043　2024年5月

DOI： 10.1016/j.corsci.2024.112043 　

ISSN：0010-938X

Microscopic visualization of hydrogen diffusion in UNS S32750 super duplex stainless steel: Roles of crystal structure and grain size 査読有り

Hiroshi Kakinuma, Saya Ajito, Motomichi Koyama, Eiji Akiyama

International Journal of Hydrogen Energy　59　866-873　2024年3月15日

DOI： 10.1016/j.ijhydene.2024.02.069 　

ISSN：0360-3199

An atomistic study on the HELP mechanism of hydrogen embrittlement in pure metal Fe 査読有り

Md Shahrier Hasan, Mehmet Fazil Kapci, Burak Bal, Motomichi Koyama, Hadia Bayat, Wenwu Xu

International Journal of Hydrogen Energy　57　60-68　2024年2月29日

DOI： 10.1016/j.ijhydene.2023.12.274 　

ISSN：0360-3199

Hydrogen Embrittlement Property of a 1.5 GPa Dual-Phase Steel Evaluated Using U-bending Test: A Comparison with Tempered Martensitic Steel with Identical Tensile Strength 査読有り

Shuya Chiba, Motomichi Koyama, Tomohiko Hojo, Saya Ajito, Yuki Shibayama, Rama Srinivas Varanasi, Eiji Akiyama

ISIJ International　64　(4)　706-713　2024年2月28日

DOI： 10.2355/isijinternational.isijint-2023-287 　

ISSN：0915-1559

eISSN：1347-5460

Hydrogen-assisted localized plasticity driven by dislocation pinning-depinning: Finite element simulations 査読有り

Daisuke Sasaki, Yuki Kusaba, Motomichi Koyama

International Journal of Hydrogen Energy　56　280-288　2024年2月22日

DOI： 10.1016/j.ijhydene.2023.12.053 　

ISSN：0360-3199

Plasticity-induced Hydrogen Desorptions Associated with Hydrogen-assisted Martensitic Transformation and Deformation Twinning in Austenitic Stainless Steels

Yifei Wen, Motomichi Koyama, Tomohiko Hojo, Saya Ajito, Eiji Akiyama

ISIJ International　64　(2)　474-481　2024年1月30日

DOI： 10.2355/isijinternational.isijint-2023-130 　

ISSN：0915-1559

eISSN：1347-5460

In situ visualization of misorientation-dependent hydrogen diffusion at grain boundaries of pure polycrystalline Ni using a hydrogen video imaging system 査読有り

Hiroshi Kakinuma, Saya Ajito, Tomohiko Hojo, Motomichi Koyama, Eiji Akiyama

Acta Materialia　263　119536-119536　2024年1月15日

DOI： 10.1016/j.actamat.2023.119536 　

ISSN：1359-6454

Critical role of initial multi-phase microstructure on the phase transformations during hydrogenation in Fe–Mo alloy system 査読有り

Rama Srinivas Varanasi, Motomichi Koyama, Reina Utsumi, Hiroyuki Saitoh, Toyoto Sato, Shin ichi Orimo, Eiji Akiyama

International Journal of Hydrogen Energy　50　1418-1434　2024年1月2日

DOI： 10.1016/j.ijhydene.2023.09.268 　

ISSN：0360-3199

Dual grain size-effects on hydrogen-assisted fatigue crack growth in 1 GPa-class medium-carbon martensitic steel 査読有り

Yuhei Ogawa, Kazuhiro Kuriyama, Motomichi Koyama

International Journal of Hydrogen Energy　50　108-115　2024年1月2日

DOI： 10.1016/j.ijhydene.2023.08.317 　

ISSN：0360-3199

Enhancing prior austenite grain boundary coherency by introducing partial bainite in martensitic steel

Ji Hoon Kim, Goro Miyamoto, Akinobu Shibata, Tomohiko Hojo, Motomichi Koyama, Yongjie Zhang, Tadashi Furuhara

Proceedings of International Symposia on Steel Science　2024　169-172　2024年

DOI： 10.2355/isijisss.2024.0_169 　

eISSN：2759-6621

Local Yield Stress and Its Unusual Independence on Multi-axial Stress States during Lüders Deformation of Medium-Mn, High-strength Steel

Takashi Matsuno, Koki Furukawa, Yoshitaka Okitsu, Motomichi Koyama, Toshihiro Tsuchiyama

ISIJ International　64　(5)　859-867　2024年

DOI： 10.2355/isijinternational.ISIJINT-2023-326 　

ISSN：0915-1559

Grain Refinement Effect on Resistance to Hydrogen-assisted Crack Growth in Equiatomic CoCrFeNi High-entropy Alloy with Different H Charging Conditions

Taein Kong, Haoyu Wang, Taekyung Lee, Motomichi Koyama, Eiji Akiyama

ISIJ International　64　(4)　688-695　2024年

DOI： 10.2355/ISIJINTERNATIONAL.ISIJINT-2023-218 　

ISSN：0915-1559

Overview of Hydrogen Effects on γ -ϵ Martensitic Transformation in Steels

Motomichi Koyama, Satoshi Iikubo, Rama Srinivas Varanasi

ISIJ International　64　(4)　732-741　2024年

DOI： 10.2355/isijinternational.ISIJINT-2023-243 　

ISSN：0915-1559

Visualization of Microscopic Hydrogen Diffusion in Polycrystalline Pure Ni Using an Ir Complex

Saya Ajito, Hiroshi Kakinuma, Motomichi Koyama, Eiji Akiyama

MATERIALS TRANSACTIONS　65　(11)　1436-1441　2024年

DOI： 10.2320/matertrans.mt-c2024008 　

ISSN：1345-9678

eISSN：1347-5320

Strain rate-dependent tensile deformation behavior and fracture mechanism of Mn–N bearing lean duplex stainless steel 査読有り

Yongxin Wang, Lei Chen, Lizi Shao, Shuo Hao, Motomichi Koyama, Xingzhou Cai, Xiaocong Ma, Miao Jin

Materials Science and Engineering: A　889　2024年1月

DOI： 10.1016/j.msea.2023.145832 　

ISSN：0921-5093

Hierarchical Deformation Heterogeneity during Lüders Band Propagation in an Fe-5Mn-0.1C Medium Mn Steel Clarified through in situ Scanning Electron Microscopy 査読有り

Motomichi Koyama, Takayuki Yamashita, Satoshi Morooka, Zhipeng Yang, Rama Srinivas Varanasi, Tomohiko Hojo, Takuro Kawasaki, Stefanus Harjo

Tetsu-To-Hagane/Journal of the Iron and Steel Institute of Japan　110　(3)　205-216　2024年

DOI： 10.2355/tetsutohagane.TETSU-2023-052 　

ISSN：0021-1575

Quantitative Evaluation of the Relationship between Strain and Color Change in Opal Photonic Crystal Films and Application into Complex Specimen Geometries 査読有り

Yutao Zhou, Zhipeng Yang, Motomichi Koyama, Saya Ajito, Tomohiko Hojo, Hiroshi Fudouzi, Eiji Akiyama

Tetsu-To-Hagane/Journal of the Iron and Steel Institute of Japan　110　(3)　311-320　2024年

DOI： 10.2355/tetsutohagane.TETSU-2023-020 　

ISSN：0021-1575

Stress and Plastic Strain Partitioning Behaviors and Those Contributions to Martensitic Transformation of Retained Austenite in Medium Manganese and Transformation- Induced Plasticity-Aided Bainitic Ferrite Steels 査読有り

Tomohiko Hojo, Motomichi Koyama, Bakuya Kumai, Yutao Zhou, Yuki Shibayama, Ayumi Shiro, Takahisa Shobu, Hiroyuki Saitoh, Saya Ajito, Eiji Akiyama

Tetsu-To-Hagane/Journal of the Iron and Steel Institute of Japan　110　(3)　227-240　2024年

DOI： 10.2355/tetsutohagane.TETSU-2023-062 　

ISSN：0021-1575

Local Yield Stress and its Unusual Independence on Multi-axial Stress States during Lüders Deformation of Medium-Mn, High-strength Steel 査読有り

Takashi Matsuno, Koki Furukawa, Yoshitaka Okitsu, Motomichi Koyama, Toshihiro Tsuchiyama

Tetsu-To-Hagane/Journal of the Iron and Steel Institute of Japan　110　(3)　217-226　2024年

DOI： 10.2355/tetsutohagane.TETSU-2023-049 　

ISSN：0021-1575

Fe-5Mn-0.1C中Mn鋼におけるリューダース変形中の微視組織および塑性の発達 査読有り

小山 元道, 山下 享介, 諸岡 聡, 澤口 孝宏, 楊 志鵬, 北條 智彦, 川崎 卓郎, ステファヌス ハルヨ

鉄と鋼　110　(3)　197-204　2024年

DOI： 10.2355/tetsutohagane.TETSU-2023-038 　

ISSN：0021-1575

eISSN：1883-2954

Temperature dependence of hydrogen-assisted damage evolution and fracture behavior in TRIP-aided bainitic ferrite steel 査読有り

Yutao Zhou, Tomohiko Hojo, Motomichi Koyama, Saya Ajito, Eiji Akiyama

Materials Science and Engineering: A　886　2023年10月17日

DOI： 10.1016/j.msea.2023.145663 　

ISSN：0921-5093

Mesoscale quantification of grain boundary character and local plasticity in hydrogen-assisted intergranular and intergranular-like cracking paths in tempered martensitic steel 査読有り

Tingshu Chen, Motomichi Koyama, Takahiro Chiba, Eiji Akiyama, Kenichi Takai

Materials Science and Engineering: A　886　145718-145718　2023年10月17日

DOI： 10.1016/j.msea.2023.145718 　

ISSN：0921-5093

Hydrogen-Induced Delayed Fracture in a 1.5 GPa Dual-Phase Steel via Coalescence of Surface and Sub-surface Cracks 査読有り

Rama Srinivas Varanasi, Motomichi Koyama, Yuki Shibayama, Shuya Chiba, Saya Ajito, Tomohiko Hojo, Eiji Akiyama

Metallurgical and Materials Transactions A: Physical Metallurgy and Materials Science　54　(8)　2989-2997　2023年8月

DOI： 10.1007/s11661-023-07096-8 　

ISSN：1073-5623

eISSN：1543-1940

Environment-assisted cracking of AZ31 magnesium alloy in a borate buffer solution containing ammonium thiocyanate under various potentials 査読有り

Saya Ajito, Tomohiko Hojo, Motomichi Koyama, Sachiko Hiromoto, Eiji Akiyama

Corrosion Science　218　2023年7月1日

DOI： 10.1016/j.corsci.2023.111195 　

ISSN：0010-938X

Phase transformations and microstructure evolutions during depressurization of hydrogenated Fe–Mn–Si–Cr alloy 査読有り

Rama Srinivas Varanasi, Motomichi Koyama, Hiroyuki Saitoh, Reina Utsumi, Toyoto Sato, Shin ichi Orimo, Eiji Akiyama

International Journal of Hydrogen Energy　48　(27)　10081-10088　2023年3月29日

DOI： 10.1016/j.ijhydene.2022.11.274 　

ISSN：0360-3199

Mechanical loading effect on the hydrogen uptake of tempered martensite steel: Elastic strain effect vs. plastic strain effect 査読有り

Yota Masuda, Motomichi Koyama, Hiroshi Kakinuma, Eiji Akiyama

Materials Science and Engineering: A　862　144486-144486　2023年1月18日

DOI： 10.1016/j.msea.2022.144486 　

ISSN：0921-5093

Crack Tip Deformation during Dwell Fatigue and Its Correlation with Crack/Fracture Surface Morphologies in a Bi–Modal Ti–6Al–4V Alloy 査読有り

Aoki Yuma, Koyama Motomichi, Tanaka Masaki, Tsuzaki Kaneaki

Nippon Kinzoku Gakkaishi/Journal of the Japan Institute of Metals　87　(12)　309-318　2023年

DOI： 10.2320/jinstmet.J2023022 　

ISSN：0021-4876

Effect of Stretch-forming on Hydrogen Diffusion Behavior in High-strength Steel Sheet 査読有り

Hayato Nishimura, Saya Ajito, Tomohiko Hojo, Motomichi Koyama, Ken-ichi Fujita, Yuki Shibayama, Hiroshi Kakinuma, Eiji Akiyama

ISIJ International　64　(4)　637-644　2023年

DOI： 10.2355/isijinternational.isijint-2023-149 　

ISSN：0915-1559

eISSN：1347-5460

Transformation-Induced Microcracks and Their Arrest with Different Deformation Temperatures in a Medium Mn Steel 査読有り

Yutao Zhou, Motomichi Koyama, Tomohiko Hojo, Saya Ajito, Eiji Akiyama

Metallurgical and Materials Transactions A　54　(1)　153-166　2023年1月

DOI： 10.1007/s11661-022-06855-3 　

ISSN：1073-5623

eISSN：1543-1940

Mixed type brittle fracture in 1.5 GPa dual-phase steel via {100} ferrite cleavage cracking 査読有り

Rama Srinivas Varanasi, Motomichi Koyama, Yuki Shibayama, Eiji Akiyama

Materials Science and Engineering: A　857　2022年11月1日

DOI： 10.1016/j.msea.2022.144021 　

ISSN：0921-5093

Hierarchical Deformation Heterogeneity during Lüders Band Propagation in an Fe-5Mn-0.1C Medium Mn Steel Clarified through &lt;i&gt;in situ&lt;/i&gt; Scanning Electron Microscopy 査読有り

Motomichi Koyama, Takayuki Yamashita, Satoshi Morooka, Zhipeng Yang, Rama Srinivas Varanasi, Tomohiko Hojo, Takuro Kawasaki, Stefanus Harjo

ISIJ International　62　(10)　2043-2053　2022年10月15日

DOI： 10.2355/isijinternational.isijint-2022-098 　

ISSN：0915-1559

eISSN：1347-5460

Microstructure and Plasticity Evolution During Lüders Deformation in an Fe-5Mn-0.1C Medium-Mn Steel 査読有り

Motomichi Koyama, Takayuki Yamashita, Satoshi Morooka, Takahiro Sawaguchi, Zhipeng Yang, Tomohiko Hojo, Takuro Kawasaki, Stefanus Harjo

ISIJ International　62　(10)　2036-2042　2022年10月15日

DOI： 10.2355/isijinternational.isijint-2021-510 　

ISSN：0915-1559

eISSN：1347-5460

Strain Rate and Temperature Effects on Hydrogen Embrittlement of Stable and Metastable High-Entropy Alloys 査読有り

M. Koyama, K. Ichii, K. Tsuzaki

Physical Mesomechanics　25　(5)　385-392　2022年10月

DOI： 10.1134/S1029959922050010 　

ISSN：1029-9599

eISSN：1990-5424

Transition mechanism of cycle- to time-dependent acceleration of fatigue crack-growth in 0.4 %C Cr-Mo steel in a pressurized gaseous hydrogen environment 査読有り

Atsuki Setoyama, Yuhei Ogawa, Masami Nakamura, Yuya Tanaka, Tingshu Chen, Motomichi Koyama, Hisao Matsunaga

International Journal of Fatigue　163　107039-107039　2022年10月

DOI： 10.1016/j.ijfatigue.2022.107039 　

ISSN：0142-1123

In situ 2D mapping of hydrogen entry into an Fe sheet under a droplet of NaCl solution using a hydrogenochromic sensor 査読有り

Hiroshi Kakinuma, Saya Ajito, Tomohiko Hojo, Motomichi Koyama, Sachiko Hiromoto, Eiji Akiyama

International Journal of Hydrogen Energy　47　(90)　38468-38476　2022年9月

DOI： 10.1016/j.ijhydene.2022.09.006 　

ISSN：0360-3199

Simultaneous observations of the corrosion behavior of an Fe sheet and the associated hydrogen distribution therein employing a hydrogenochromic sensor 査読有り

Hiroshi Kakinuma, Saya Ajito, Tomohiko Hojo, Motomichi Koyama, Sachiko Hiromoto, Eiji Akiyama

Corrosion Science　206　110534-110534　2022年9月

DOI： 10.1016/j.corsci.2022.110534 　

ISSN：0010-938X

Hydrogen-accelerated fatigue crack growth of equiatomic Fe–Cr–Ni–Mn–Co high-entropy alloy evaluated by compact tension testing 査読有り

Motomichi Koyama, Shunsuke Mizumachi, Eiji Akiyama, Kaneaki Tsuzaki

Materials Science and Engineering A　848　2022年7月19日

DOI： 10.1016/j.msea.2022.143394 　

ISSN：0921-5093

Synergistic effects of hydrogen and deformation temperature on mechanical properties of TRIP-aided bainitic ferrite steel 査読有り

Yutao Zhou, Tomohiko Hojo, Motomichi Koyama, Saya Ajito, Eiji Akiyama

Materials Science and Engineering A　842　2022年5月11日

DOI： 10.1016/j.msea.2022.143070 　

ISSN：0921-5093

Comparative study of stress and strain partitioning behaviors in medium manganese and transformation-induced plasticity-aided bainitic ferrite steels

Tomohiko Hojo, Motomichi Koyama, Bakuya Kumai, Yuki Shibayama, Ayumi Shiro, Takahisa Shobu, Hiroyuki Saitoh, Saya Ajito, Eiji Akiyama

Scripta Materialia　210　2022年3月15日

DOI： 10.1016/j.scriptamat.2021.114463 　

ISSN：1359-6462

Austenite stabilization kinetics in early stages of austempering treatment in TRIP-aided steel using in-situ neutron diffraction technique

Yutao Zhou, Tomohiko Hojo, Amane Kitahara, Yusuke Onuki, Shigeo Sato, Motomichi Koyama, Eiji Akiyama

Materialia　21　2022年3月

DOI： 10.1016/j.mtla.2022.101317 　

eISSN：2589-1529

Effects of Thermomechanical Processing on Hydrogen Embrittlement Properties of Ultrahigh-Strength TRIP-Aided Bainitic Ferrite Steels

Tomohiko Hojo, Yutao Zhou, Junya Kobayashi, Koh Ichi Sugimoto, Yoshito Takemoto, Akihiko Nagasaka, Motomichi Koyama, Saya Ajito, Eiji Akiyama

Metals　12　(2)　2022年2月

DOI： 10.3390/met12020269 　

eISSN：2075-4701

Effects of Ammonium Thiocyanate and pH of Aqueous Solutions on Hydrogen Absorption into Iron under Cathodic Polarization

Saya Ajito, Tomohiko Hojo, Motomichi Koyama, Eiji Akiyama

Tetsu-to-Hagane　108　(11)　857-863　2022年

DOI： 10.2355/tetsutohagane.tetsu-2022-043 　

ISSN：0021-1575

eISSN：1883-2954

Quantitative Evaluation of the Relationship between Strain and Color Change in Opal Photonic Crystal Films and Application into Complex Specimen Geometries 査読有り

Yutao Zhou, Zhipeng Yang, Motomichi Koyama, Saya Ajito, Tomohiko Hojo, Hiroshi Fudouzi, Eiji Akiyama

ISIJ International　2022年

DOI： 10.2355/isijinternational.isijint-2022-054 　

ISSN：0915-1559

eISSN：1347-5460

Effect of Stretch-forming on Hydrogen Diffusion Behavior in High-strength Steel Sheet

Hayato Nishimura, Saya Ajito, Tomohiko Hojo, Motomichi Koyama, Ken-ichi Fujita, Yuki Shibayama, Hiroshi Kakinuma, Eiji Akiyama

Tetsu-to-Hagane　108　(5)　316-324　2022年

DOI： 10.2355/tetsutohagane.tetsu-2021-096 　

ISSN：0021-1575

eISSN：1883-2954

Multi-Probe Characterization of Plasticity Heterogeneity: Requirement of Alloy Design Considering Dislocation Planarity for Developing Crack-Resistant Ni–Cr Alloys

Taein Kong, Motomichi Koyama, Misaho Yamamura, Eiji Akiyama

MATERIALS TRANSACTIONS　63　(1)　88-91　2022年1月1日

DOI： 10.2320/matertrans.mt-m2021191 　

ISSN：1345-9678

eISSN：1347-5320

Cr Effects on the Local Plasticity Evolution and Fracture Behaviors of Ni–Cr Alloys Tensile–Tested under Hydrogen Charging 査読有り

Naohiro Kobayashi, Motomichi Koyama, Misaho Yamamura, Tomohiko Hojo, Eiji Akiyama

Nippon Kinzoku Gakkaishi/Journal of the Japan Institute of Metals　86　(5)　77-84　2022年

DOI： 10.2320/JINSTMET.J2021054 　

ISSN：0021-4876

Real-Time Visualization of Hydrogen Distribution in Metals Using Polyaniline: An Ultrasensitive Hydrogenochromic Sensor

Hiroshi Kakinuma, Saya Ajito, Tomohiko Hojo, Motomichi Koyama, Eiji Akiyama

Advanced Materials Interfaces　9　(18)　2022年

DOI： 10.1002/admi.202101984 　

eISSN：2196-7350

Hydrogen Embrittlement Behavior of Pure Ni and Ni-20Cr Alloy with Different Grain Sizes

Naohiro Kobayashi, Motomichi Koyama, Kenji Kobayashi, Tomohiko Hojo, Eiji Akiyama

Materials Transactions　63　(2)　247-256　2022年

DOI： 10.2320/matertrans.MT-M2021170 　

ISSN：1345-9678

Annealing Time Effects on Mechanically Long Fatigue Crack Growth of TRIP-maraging Steels

Tomoki Mizoguchi, Motomichi Koyama, Hiroshi Noguchi

ISIJ International　62　(2)　399-401　2022年

DOI： 10.2355/isijinternational.ISIJINT-2021-093 　

ISSN：0915-1559

Factors Distinguishing Hydrogen-Assisted Intergranular and Intergranular-Like Fractures in a Tempered Lath Martensitic Steel

Tingshu Chen, Takahiro Chiba, Motomichi Koyama, Eiji Akiyama, Kenichi Takai

Metallurgical and Materials Transactions A: Physical Metallurgy and Materials Science　53　(5)　1645-1658　2022年

DOI： 10.1007/s11661-022-06608-2 　

ISSN：1073-5623

Pre-straining alters hydrogen-assisted cracking site and local hydrogen diffusivity in a nitrogen-doped duplex steel

Milene Yumi Maeda, Motomichi Koyama, Hayato Nishimura, Osvaldo Mitsuyuki Cintho, Eiji Akiyama

Scripta Materialia　207　114272-114272　2022年1月

DOI： 10.1016/j.scriptamat.2021.114272 　

ISSN：1359-6462

Quantification and Characterization of Microdamage Resistance in Metals for Designing High-Strength Ductile Microstructures

Motomichi Koyama

Accounts of Materials Research　2　(12)　1167-1176　2021年12月24日

DOI： 10.1021/accountsmr.1c00160 　

ISSN：2643-6728

eISSN：2643-6728

Notch shape dependence of fatigue crack extension in equiatomic CrMnFeCoNi high-entropy alloy

Kai Suzuki, Shigeru Hamada, Motomichi Koyama, Kaneaki Tsuzaki, Hiroshi Noguchi

International Journal of Fatigue　153　2021年12月

DOI： 10.1016/j.ijfatigue.2021.106481 　

ISSN：0142-1123

Hydrogenation treatment under several gigapascals assists diffusionless transformation in a face-centered cubic steel 査読有り

Motomichi Koyama, Hiroyuki Saitoh, Toyoto Sato, Shin-ichi Orimo, Eiji Akiyama

Scientific Reports　11　(1)　2021年12月

DOI： 10.1038/s41598-021-98938-1 　

eISSN：2045-2322

Hierarchical Characteristics of Hydrogen-Assisted Crack Growth and Microstructural Strain Evolution in Tempered Martensitic Steels: Case of Quasi-cleavage Fracture

Tingshu Chen, Takahiro Chiba, Motomichi Koyama, Akinobu Shibata, Eiji Akiyama, Kenichi Takai

Metallurgical and Materials Transactions A　52　(10)　4703-4713　2021年10月

DOI： 10.1007/s11661-021-06423-1 　

ISSN：1073-5623

eISSN：1543-1940

Twinning-Induced Plasticity (TWIP) Steel 招待有り 査読有り

Motomichi Koyama

Encyclopedia of Materials: Metals and Alloys　95-105　2021年9月1日

DOI： 10.1016/B978-0-12-819726-4.00067-3 　

Hydrogen embrittlement and associated surface crack growth in fine-grained equiatomic CoCrFeMnNi high-entropy alloys with different annealing temperatures evaluated by tensile testing under in situ hydrogen charging 査読有り

Haoyu Wang, Motomichi Koyama, Tomohiko Hojo, Eiji Akiyama

International Journal of Hydrogen Energy　46　(65)　33028-33038　2021年9月

DOI： 10.1016/j.ijhydene.2021.07.136 　

ISSN：0360-3199

Depressurization-induced diffusionless transformation in pure iron hydrogenated under several gigapascals 査読有り

Motomichi Koyama, Hiroyuki Saitoh, Toyoto Sato, Shin-ichi Orimo, Eiji Akiyama

Materials Letters: X　11　100078-100078　2021年9月

DOI： 10.1016/j.mlblux.2021.100078 　

ISSN：2590-1508

eISSN：2590-1508

Strain rate sensitivity of hydrogen-assisted ε-martensitic transformation and associated hydrogen embrittlement in high-Mn steel 査読有り

Chunxi Hao, Motomichi Koyama, Saya Ajito, Eiji Akiyama

International Journal of Hydrogen Energy　46　(53)　27221-27233　2021年8月

DOI： 10.1016/j.ijhydene.2021.05.162 　

ISSN：0360-3199

Effect of austempering treatment on the microstructure and mechanical properties of 0.4C–1.5Si-1.5Mn TRIP-aided bainitic ferrite steel

Yutao Zhou, Tomohiko Hojo, Motomichi Koyama, Eiji Akiyama

Materials Science and Engineering: A　819　141479-141479　2021年7月

DOI： 10.1016/j.msea.2021.141479 　

ISSN：0921-5093

Effects of Stress and Plastic Strain on Hydrogen Embrittlement Fracture of a U-bent Martensitic Steel Sheet

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

ISIJ International　61　(4)　1322-1329　2021年4月15日

DOI： 10.2355/isijinternational.isijint-2020-569 　

ISSN：0915-1559

eISSN：1347-5460

Roles of Hydrogen Content and Pre-strain on Damage Evolution of TRIP-aided Bainitic Ferrite Steel

Virendra Kumar Verma, Motomichi Koyama, Bakuya Kumai, Tomohiko Hojo, Eiji Akiyama

ISIJ International　61　(4)　1309-1314　2021年4月15日

DOI： 10.2355/isijinternational.isijint-2020-514 　

ISSN：0915-1559

eISSN：1347-5460

Effects of Ammonium Thiocyanate and pH of Aqueous Solutions on Hydrogen Absorption into Iron under Cathodic Polarization

Saya Ajito, Tomohiko Hojo, Motomichi Koyama, Eiji Akiyama

ISIJ International　61　(4)　1209-1214　2021年4月15日

DOI： 10.2355/isijinternational.isijint-2020-551 　

ISSN：0915-1559

eISSN：1347-5460

Effects of Residual Stress on Hydrogen Embrittlement of a Stretch-Formed Tempered Martensitic Steel Sheet

Hayato Nishimura, Tomohiko Hojo, Saya Ajito, Yuki Shibayama, Motomichi Koyama, Hiroyuki Saitoh, Ayumi Shiro, Ryo Yasuda, Takahisa Shobu, Eiji Akiyama

ISIJ International　61　(4)　1170-1178　2021年4月15日

DOI： 10.2355/isijinternational.isijint-2020-492 　

ISSN：0915-1559

eISSN：1347-5460

Novel −75°C SEM cooling stage: application for martensitic transformation in steel

Kaneaki Tsuzazki, Motomichi Koyama, Ryosuke Sasaki, Keiichiro Nakafuji, Kazushi Oie, Akinobu Shibata, Takashi Gondo, Hiroya Miyazaki, Hiroshi Akamine, Minoru Nishida

Microscopy　70　(2)　250-254　2021年3月24日

DOI： 10.1093/jmicro/dfaa051 　

ISSN：2050-5698

eISSN：2050-5701

Effects of matrix structure and nitrogen content on fatigue properties of ultrahigh-strength low alloy trip-aided steels

Tomohiko Hojo, Junya Kobayashi, Koh Ichi Sugimoto, Yoshito Takemoto, Akihiko Nagasaka, Motomichi Koyama, Eiji Akiyama

ISIJ International　61　(2)　591-598　2021年2月15日

DOI： 10.2355/isijinternational.ISIJINT-2020-392 　

ISSN：0915-1559

Fatigue crack growth at different frequencies and temperatures in an fe-based metastable high-entropy alloy

Motomichi Koyama, Takeshi Eguchi, Kaneaki Tsuzaki

ISIJ International　61　(2)　641-647　2021年2月15日

DOI： 10.2355/isijinternational.ISIJINT-2020-504 　

ISSN：0915-1559

Three-dimensional characterization of low-cycle fatigue crack morphology in TRIP-maraging steel: Crack closure, geometrical uncertainty and wear

Zhao Zhang, Motomichi Koyama, Kaneaki Tsuzaki, Hiroshi Noguchi

International Journal of Fatigue　143　2021年2月

DOI： 10.1016/j.ijfatigue.2020.106032 　

ISSN：0142-1123

Hydrogen-assisted damage evolution in nitrogen-doped duplex stainless steel

Milene Yumi Maeda, Motomichi Koyama, Hayato Nishimura, Osvaldo Mitsuyuki Cintho, Eiji Akiyama

International Journal of Hydrogen Energy　46　(2)　2716-2728　2021年1月6日

DOI： 10.1016/j.ijhydene.2020.10.152 　

ISSN：0360-3199

Hydrogen-assisted crack propagation in pre-strained twinning-induced plasticity steel: From initiation at a small defect to failure

Abbas Mohammadi, Motomichi Koyama, Gregory Gerstein, Hans Jürgen Maier, Hiroshi Noguchi

ISIJ International　61　(4)　1278-1286　2021年

DOI： 10.2355/isijinternational.ISIJINT-2019-510 　

ISSN：0915-1559

Annealing time effects on mechanically long fatigue crack growth of TRIP-maraging steels

Tomoki Mizoguchi, Motomichi KoyaMa, Hiroshi Noguchi

Tetsu-To-Hagane/Journal of the Iron and Steel Institute of Japan　107　(4)　321-324　2021年

DOI： 10.2355/TETSUTOHAGANE.TETSU-2020-106 　

ISSN：0021-1575

Effects of Residual Stress on Hydrogen Embrittlement of a Stretch-Formed Tempered Martensitic Steel Sheet

Hayato Nishimura, Tomohiko Hojo, Saya Ajito, Yuki Shibayama, Motomichi Koyama, Hiroyuki Saitoh, Ayumi Shiro, Ryo Yasuda, Takahisa Shobu, Eiji Akiyama

Tetsu-to-Hagane　107　(9)　760-768　2021年

DOI： 10.2355/tetsutohagane.tetsu-2021-055 　

ISSN：0021-1575

eISSN：1883-2954

Availability of Opal Photonic Crystal Films for Visualizing Heterogeneous Strain Evolution in Steels: Example of Lüders Deformation

Zhipeng Yang, Motomichi Koyama, Hiroshi Fudouzi, Tomohiko Hojo, Eiji Akiyama

Tetsu-to-Hagane　107　(8)　681-686　2021年

DOI： 10.2355/tetsutohagane.tetsu-2021-028 　

ISSN：0021-1575

eISSN：1883-2954

Effects of Matrix Structure and Nitrogen Content on Fatigue Properties of Ultrahigh-Strength Low Alloy TRIP-Aided Steels

Tomohiko Hojo, Junya Kobayashi, Koh-ichi Sugimoto, Yoshito Takemoto, Akihiko Nagasaka, Motomichi Koyama, Eiji Akiyama

Tetsu-to-Hagane　107　(8)　672-680　2021年

DOI： 10.2355/tetsutohagane.tetsu-2021-015 　

ISSN：0021-1575

eISSN：1883-2954

Stacking fault aggregation during cooling composing FCC–HCP martensitic transformation revealed by in-situ electron channeling contrast imaging in an Fe-high Mn alloy

Motomichi Koyama, Misaki Seo, Keiichiro Nakafuji, Kaneaki Tsuzaki

Science and Technology of Advanced Materials　22　(1)　135-140　2021年

DOI： 10.1080/14686996.2021.1877570 　

ISSN：1468-6996

eISSN：1878-5514

Potential Effects of Short-Range Order on Hydrogen Embrittlement of Stable Austenitic Steels—A Review 招待有り

Motomichi Koyama, Burak Bal, Dermican Canadinc, Kishan Habib, Toshihiro Tsuchiyama, Kaneaki Tsuzaki, Eiji Akiyama

Advanced Structured Materials　143　1-18　2021年

DOI： 10.1007/978-3-030-66948-5_1 　

ISSN：1869-8433

eISSN：1869-8441

Hydrogen embrittlement behavior of pure ni and ni–20cr alloy with different grain sizes

Naohiro Kobayashi, Motomichi Koyama, Kenji Kobayashi, Tomohiko Hojo, Eiji Akiyama

Nippon Kinzoku Gakkaishi/Journal of the Japan Institute of Metals　85　(2)　49-58　2021年

DOI： 10.2320/JINSTMET.J2020036 　

ISSN：0021-4876

{111} trace analysis in ECC images-toward in-situ observation of deformation behavior in FCC bulk specimens

Motomichi Koyama, Keiichiro Nakafuji, Kaneaki Tsuzaki

Nippon Kinzoku Gakkaishi/Journal of the Japan Institute of Metals　85　(1)　17-22　2021年

DOI： 10.2320/JINSTMET.JD202003 　

ISSN：0021-4876

Quantitative Evaluation of Hydrogen Effects on Evolutions of Deformation-Induced ε-Martensite and Damage in a High-Mn Steel

Chunxi Hao, Motomichi Koyama, Eiji Akiyama

Metallurgical and Materials Transactions A: Physical Metallurgy and Materials Science　51　(12)　6184-6194　2020年12月

DOI： 10.1007/s11661-020-06021-7 　

ISSN：1073-5623

In-Situ Electron Channeling Contrast Imaging under Tensile Loading: Residual Stress, Dislocation Motion, and Slip Line Formation 査読有り

Keiichiro Nakafuji, Motomichi Koyama, Kaneaki Tsuzaki

Scientific Reports　10　(1)　2020年12月1日

DOI： 10.1038/s41598-020-59429-x 　

eISSN：2045-2322

Availability of Opal Photonic Crystal Films for Visualizing Heterogeneous Strain Evolution in Steels: Example of Lüders Deformation 査読有り

Zhipeng Yang, Motomichi Koyama, Hiroshi Fudouzi, Tomohiko Hojo, Eiji Akiyama

ISIJ International　60　(11)　2604-2608　2020年11月15日

DOI： 10.2355/isijinternational.ISIJINT-2020-223 　

ISSN：0915-1559

eISSN：1347-5460

Pre-strain effects on critical stress and hydrogen content for hydrogen-induced quasi-cleavage fracture in a TRIP-aided bainitic ferrite steel: Martensitic transformation, matrix damage, and strain aging

Bakuya Kumai, Tomohiko Hojo, Motomichi Koyama, Eiji Akiyama, Hiroyuki Waki, Akihiko Nagasaka

International Journal of Hydrogen Energy　45　(51)　27920-27928　2020年10月16日

DOI： 10.1016/j.ijhydene.2020.07.036 　

ISSN：0360-3199

Shallow crack effect on evaluation of residual tensile strength: Harmless and stable cracks in finite-sized structure made of ductile metals

He Liu, Shigeru Hamada, Motomichi Koyama, Hiroshi Noguchi

Theoretical and Applied Fracture Mechanics　109　2020年10月

DOI： 10.1016/j.tafmec.2020.102734 　

ISSN：0167-8442

Application of an iridium complex for detecting hydrogen permeation through pure iron 査読有り

Saya Ajito, Tomohiko Hojo, Motomichi Koyama, Ken ichi Fujita, Eiji Akiyama

International Journal of Hydrogen Energy　45　(46)　25580-25586　2020年9月21日

DOI： 10.1016/j.ijhydene.2020.06.113 　

ISSN：0360-3199

Hydrogen embrittlement resistance of pre-strained ultra-high-strength low alloy TRIP-aided steel

Tomohiko Hojo, Bakuya Kumai, Motomichi Koyama, Eiji Akiyama, Hiroyuki Waki, Hiroyuki Saitoh, Ayumi Shiro, Ryo Yasuda, Takahisa Shobu, Akihiko Nagasaka

International Journal of Fracture　224　(2)　253-260　2020年8月1日

DOI： 10.1007/s10704-020-00451-5 　

ISSN：0376-9429

eISSN：1573-2673

Distinguishing geometric and metallurgic hydrogen-embrittlement susceptibilities in pre-cracked structures made of interstitial-free steel under monotonic tension

He Liu, Shigeru Hamada, Motomichi Koyama, Hiroshi Noguchi

Theoretical and Applied Fracture Mechanics　108　2020年8月

DOI： 10.1016/j.tafmec.2020.102574 　

ISSN：0167-8442

Equivalence between shallow notch and shallow crack in structural failure caused by plastic instability

He Liu, Shigeru Hamada, Motomichi Koyama, Hiroshi Noguchi

Theoretical and Applied Fracture Mechanics　108　2020年8月

DOI： 10.1016/j.tafmec.2020.102577 　

ISSN：0167-8442

Influence of dynamic-strain aging due to excess Mg on fatigue crack growth rate scatter in Al6061-T6 alloy

Samsol Faizal Anis, Motomichi Koyama, Shigeru Hamada, Hiroshi Noguchi

Theoretical and Applied Fracture Mechanics　108　2020年8月

DOI： 10.1016/j.tafmec.2020.102617 　

ISSN：0167-8442

Effects of hydrogen content that alters damage evolution mechanisms in SUH 660 precipitation-strengthened Fe–Cr–Ni steel

Virendra Kumar Verma, Motomichi Koyama, Shigeru Hamada, Eiji Akiyama

Materials Science and Engineering A　791　2020年7月22日

DOI： 10.1016/j.msea.2020.139750 　

ISSN：0921-5093

Simplified stress field determination for an inclined crack and interaction between two cracks under tension

Samsol Faizal Anis, Motomichi Koyama, Shigeru Hamada, Hiroshi Noguchi

Theoretical and Applied Fracture Mechanics　107　2020年6月

DOI： 10.1016/j.tafmec.2020.102561 　

ISSN：0167-8442

Fatigue behavior in an Fe-N binary ferritic steel: Similarity and difference between carbon and nitrogen 査読有り

Kishan Habib, Motomichi Koyama, Eisaku Sakurada, Nobuyuki Yoshimura, Tatsuo Yokoi, Kohsaku Ushioda, Kaneaki Tsuzaki, Hiroshi Noguchi

Tetsu-To-Hagane/Journal of the Iron and Steel Institute of Japan　106　(6)　123-129　2020年6月

DOI： 10.2355/tetsutohagane.TETSU-2019-051 　

ISSN：0021-1575

Thermal Stability of Resistance to Propagation of Mechanically Small Fatigue-cracks in an Fe-N Binary Ferritic Steel 査読有り

Motomichi Koyama, Kishan Habib, Tatsuo Yokoi, Eisaku Sakurada, Nobuyuki Yoshimura, Kohsaku Ushioda, Kaneaki Tsuzaki, Hiroshi Noguchi

Tetsu-To-Hagane/Journal of the Iron and Steel Institute of Japan　106　(6)　130-138　2020年6月

DOI： 10.2355/tetsutohagane.TETSU-2019-091 　

ISSN：0021-1575

Influence of Mn addition on fatigue limit and coaxing effect in ferritic steel containing solute carbon 査読有り

Yusui Uchida, Motomichi Koyama, Yoshihiro Fukushima, Kaneaki Tsuzaki

Tetsu-To-Hagane/Journal of the Iron and Steel Institute of Japan　106　(6)　112-122　2020年6月

DOI： 10.2355/tetsutohagane.TETSU-2019-092 　

ISSN：0021-1575

Fundamental criterion K<inf>trans</inf> for failure analysis of hydrogen-assisted cracks in notched specimens of pure Ni 査読有り

Tingshu Chen, Motomichi Koyama, Shigeru Hamada, Hiroshi Noguchi

Theoretical and Applied Fracture Mechanics　107　2020年6月

DOI： 10.1016/j.tafmec.2020.102556 　

ISSN：0167-8442

Multiple damage mechanisms facilitated by planar dislocation glide in a commercial-grade precipitation-strengthened Fe–Ni–Cr-based steel 査読有り

Virendra Kumar Verma, Motomichi Koyama, Shigeru Hamada, Eiji Akiyama

Materials Science and Engineering A　782　139250　2020年4月

DOI： 10.1016/j.msea.2020.139250 　

ISSN：0921-5093

Planar slip-driven fatigue crack initiation and propagation in an equiatomic CrMnFeCoNi high-entropy alloy 査読有り

Kai Suzuki, Motomochi Koyama, Shigeru Hamada, Kaneaki Tsuzaki, Hiroshi Noguchi

International Journal of Fatigue　133　2020年4月

DOI： 10.1016/j.ijfatigue.2019.105418 　

ISSN：0142-1123

Plastic deformation sequence and strain gradient characteristics of hydrogen-induced delayed crack propagation in single-crystalline Fe–Si alloy 査読有り

Thanh Thuong Huynh, Motomichi Koyama, Yoshimasa Takahashi, Shigeru Hamada, Kaneaki Tsuzaki, Hiroshi Noguchi

Scripta Materialia　178　99-103　2020年3月15日

DOI： 10.1016/j.scriptamat.2019.11.012 　

ISSN：1359-6462

Fatigue crack propagation modes: plastic deformation mode and damage accumulation mode 査読有り

Shigeru Hamada, Kejin Zhang, Motomichi Koyama, Masaharu Ueda, Hiroshi Noguchi

International Journal of Fracture　222　(1-2)　111-122　2020年3月1日

DOI： 10.1007/s10704-020-00433-7 　

ISSN：0376-9429

eISSN：1573-2673

Strain rate and hydrogen effects on crack growth from a notch in a Fe-high-Mn steel containing 1.1 wt% solute carbon 査読有り

Hina Najam, Motomichi Koyama, Burak Bal, Eiji Akiyama, Kaneaki Tsuzaki

International Journal of Hydrogen Energy　45　(1)　1125-1139　2020年1月1日

DOI： 10.1016/j.ijhydene.2019.10.227 　

ISSN：0360-3199

Growth behavior of a mechanically long fatigue crack in an FeCrNiMnCo high entropy alloy: A comparison with an austenitic stainless steel 査読有り

Shunsuke Mizumachi, Motomichi Koyama, Yoshihiro Fukushima, Kaneaki Tsuzaki

ISIJ International　60　(1)　175-181　2020年

DOI： 10.2355/isijinternational.ISIJINT-2019-230 　

ISSN：0915-1559

Transformation-assisted hydrogen desorption during deformation in steels: Examples of αʹ- and ε-martensite 査読有り

T. Hojo, M. Koyama, N. Terao, K. Tsuzaki, E. Akiyama

International Journal of Hydrogen Energy　In press　2019年12月

Effect analysis of stress-intensity-factor-range decreasing rate for obtaining threshold stress-intensity-factor-range 査読有り

Bochuan Li, Motomichi Koyama, Shigeru Hamada, Hiroshi Noguchi

Theoretical and Applied Fracture Mechanics　104　2019年12月

DOI： 10.1016/j.tafmec.2019.102377 　

ISSN：0167-8442

A patient-specific numerical modeling of the spontaneous coronary artery dissection in relation to atherosclerosis 査読有り

Alireza Karimi, Reza Razaghi, Motomichi Koyama

Computer Methods and Programs in Biomedicine　182　2019年12月

DOI： 10.1016/j.cmpb.2019.105060 　

ISSN：0169-2607

eISSN：1872-7565

Mode I fatigue crack growth induced by strain-aging in precipitation-hardened aluminum alloys 査読有り

Samsol Faizal Anis, Motomichi Koyama, Shigeru Hamada, Hiroshi Noguchi

Theoretical and Applied Fracture Mechanics　104　2019年12月

DOI： 10.1016/j.tafmec.2019.102340 　

ISSN：0167-8442

Detection of hydrogen effusion before, during, and after martensitic transformation: Example of multiphase transformation-induced plasticity steel

Motomichi Koyama, Daisuke Yamasaki, Arisa Ikeda, Tomohiko Hojo, Eiji Akiyama, Kenichi Takai, Kaneaki Tsuzaki

International Journal of Hydrogen Energy　44　(47)　26028-26035　2019年10月4日

DOI： 10.1016/j.ijhydene.2019.07.254 　

ISSN：0360-3199

Effect of Hydrogen on the Substructure of Lenticular Martensite in Fe-31Ni Alloy 査読有り

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　2019年9月15日

DOI： 10.1007/s11661-019-05320-y 　

ISSN：1073-5623

Data of dynamic microscale strain distributions of Ti-6Al-4V alloys in dwell fatigue tests

Qinghua Wang, Shien Ri, Akira Maenosono, Yoshihisa Tanaka, Motomichi Koyama

Data in Brief　25　2019年8月

DOI： 10.1016/j.dib.2019.104338 　

ISSN：2352-3409

First-Principles Study of Chemical Driving Force for Face Centered Cubic to Hexagonal Close Packed Martensitic Transformation in Hydrogen-Charged Iron

Y. Kuroki, S. Kawano, S. Iikubo, H. Ohtani, M. Koyama, K. Tsuzaki

Metallurgical and Materials Transactions A: Physical Metallurgy and Materials Science　50　(7)　3019-3023　2019年7月15日

DOI： 10.1007/s11661-019-05237-6 　

ISSN：1073-5623

Strain-rate sensitivity of hydrogen-assisted damage evolution and failure in dual-phase steel: From vacancy to micrometer-scale void growth

T. Kumamoto, M. Koyama, K. Sato, K. Tsuzaki

Engineering Fracture Mechanics　216　2019年7月

DOI： 10.1016/j.engfracmech.2019.106513 　

ISSN：0013-7944

1-second-resolved strain mapping in Ti-6Al-4V alloys during dwell fatigue in SEM by video sampling moiré 査読有り

Qinghua Wang, Shien Ri, Akira Maenosono, Yoshihisa Tanaka, Motomichi Koyama

Mechanics of Materials　133　63-70　2019年6月1日

DOI： 10.1016/j.mechmat.2019.03.002 　

ISSN：0167-6636

Overview of metastability and compositional complexity effects for hydrogen-resistant iron alloys: Inverse austenite stability effects 招待有り

Motomichi Koyama, Cemal Cem Tasan, Kaneaki Tsuzaki

Engineering Fracture Mechanics　214　123-133　2019年6月1日

DOI： 10.1016/j.engfracmech.2019.03.049 　

ISSN：0013-7944

Enhancement of hydrogen embrittlement resistance of Fe-Mn-C twinning-induced plasticity steel by partial recrystallization technique 査読有り

Tak Min Park, Min Tae Kim, Kyeong Ho Baik, Motomichi Koyama, Jeongho Han

Materials Characterization　151　221-226　2019年5月1日

DOI： 10.1016/j.matchar.2019.03.014 　

ISSN：1044-5803

Lowering Strain Rate Simultaneously Enhances Carbon- and Hydrogen-Induced Mechanical Degradation in an Fe-33Mn-1.1C Steel

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　(3)　1137-1141　2019年3月15日

DOI： 10.1007/s11661-018-5080-7 　

ISSN：1073-5623

Growth behavior of a mechanically long fatigue crack in an FeCrNiMnCo high entropy alloy: A comparison with an austenitic stainless steel

Shunsuke Mizumachi, Motomichi Koyama, Yoshihiro Fukushima, Kaneaki Tsuzaki

Tetsu-To-Hagane/Journal of the Iron and Steel Institute of Japan　105　(2)　93-99　2019年2月

DOI： 10.2355/tetsutohagane.TETSU-2018-073 　

ISSN：0021-1575

EBSD and ECCI based assessments of inhomogeneous plastic strain evolution coupled with digital image correlation

Ryohei Kakimoto, Motomichi Koyama, Kaneaki Tsuzaki

Tetsu-To-Hagane/Journal of the Iron and Steel Institute of Japan　105　(2)　100-108　2019年2月

DOI： 10.2355/tetsutohagane.TETSU-2018-072 　

ISSN：0021-1575

Understanding the damage initiation mechanism of precipitation-strengthened Fe-Ni-Cr based austenitic steel

Virendra Kumar Verma, Shigeru Hamada, Motomichi Koyama

Materials Today: Proceedings　26　3081-3084　2019年

DOI： 10.1016/j.matpr.2020.02.637 　

ISSN：2214-7853

Evolution of quasi-brittle hydrogen-assisted damages in a dual-phase steel

Tsubasa Kumamoto, Motomichi Koyama, Koichi Sato, Kaneaki Tsuzaki

Nippon Kinzoku Gakkaishi/Journal of the Japan Institute of Metals　83　(7)　221-230　2019年

DOI： 10.2320/jinstmet.J2019008 　

ISSN：0021-4876

ECCI Characterization of Dislocation Structures at a Non-propagating Fatigue Crack Tip: Toward Understanding the Effects of Mn-C and Cr-N Couples on Crack Growth Resistance

Kishan Habib, Motomichi Koyama, Toshihiro Tsuchiyama, Hiroshi Noguchi

Metallurgical and Materials Transactions A: Physical Metallurgy and Materials Science　50　426-435　2019年1月1日

DOI： 10.1007/s11661-018-4972-x 　

ISSN：1073-5623

Resistance to mechanically small fatigue crack growth in ultrafine grained interstitial-free steel fabricated by accumulative roll-bonding 査読有り

X. Lin, M. Koyama, S. Gao, N. Tsuji, K. Tsuzaki, H. Noguchi

International Journal of Fatigue　118　117-125　2019年1月

DOI： 10.1016/j.ijfatigue.2018.09.002 　

ISSN：0142-1123

EBSD- And ECCI-based Assessments of Inhomogeneous Plastic Strain Evolution Coupled with Digital Image Correlation 査読有り

Ryohei Kakimoto, Motomichi Koyama, Kaneaki Tsuzaki

ISIJ International　59　(12)　2334-2342　2019年

DOI： 10.2355/isijinternational.ISIJINT-2019-232 　

ISSN：0915-1559

Evolution of quasi-brittle hydrogen-assisted damages in a dual-phase steel 査読有り

Tsubasa Kumamoto, Motomichi Koyama, Koichi Sato, Kaneaki Tsuzaki

Materials Transactions　60　(11)　2368-2377　2019年

DOI： 10.2320/matertrans.MT-M2019196 　

ISSN：1345-9678

Fatigue behavior in an Fe-N binary ferritic steel: Similarity and difference between carbon and nitrogen 査読有り

Kishan Habib, Motomichi Koyama, Eisaku Sakurada, Nobuyuki Yoshimura, Tatsuo Yokoi, Kohsaku Ushioda, Kaneaki Tsuzaki, Hiroshi Noguchi

ISIJ International　59　(1)　186-191　2019年1月

DOI： 10.2355/isijinternational.ISIJINT-2018-535 　

ISSN：0915-1559

Phase stability effects on hydrogen embrittlement resistance in martensite-reverted austenite steels. 査読有り

Metallurgical Materials Transctions A　50　(1)　29-34　2019年1月

DOI： 10.1007/s11661-018-4948-x 　

Influence of stress re-distribution on hydrogen-induced fatigue crack propagation

Daisuke Sasaki, Motomichi Koyama, Hiroshi Noguchi

ISIJ International　59　1683-1690　2019年1月1日

DOI： 10.2355/isijinternational.ISIJINT-2019-012 　

ISSN：0915-1559

Roughness-induced stress shielding effect in fatigue crack propagation under Mode II loading 査読有り

Shigeru Hamada, Taro Suemasu, Shuto Fukudome, Motomichi Koyama, Masaharu Ueda, Hiroshi Noguchi

International Journal of Fatigue　116　245-256　2018年11月1日

DOI： 10.1016/j.ijfatigue.2018.06.029 　

ISSN：0142-1123

Effect of shear-affected zone on fatigue crack propagation mode 査読有り

Shigeru Hamada, Kejin Zhang, Jiwang Zhang, Motomichi Koyama, Tatsuo Yokoi, Hiroshi Noguchi

International Journal of Fatigue　116　36-47　2018年11月1日

DOI： 10.1016/j.ijfatigue.2018.06.003 　

ISSN：0142-1123

Optical full-field strain measurement method from wrapped sampling Moiré phase to minimize the influence of defects and its applications 査読有り

Qinghua Wang, Shien Ri, Hiroshi Tsuda, Motomichi Koyama

Optics and Lasers in Engineering　110　155-162　2018年11月1日

DOI： 10.1016/j.optlaseng.2018.05.020 　

ISSN：0143-8166

First-Principles Study on Hydrogen Diffusivity in BCC, FCC, and HCP Iron

K. Hirata, S. Iikubo, M. Koyama, K. Tsuzaki, H. Ohtani

Metallurgical and Materials Transactions A: Physical Metallurgy and Materials Science　49　5015-5022　2018年10月1日

DOI： 10.1007/s11661-018-4815-9 　

ISSN：1073-5623

Fatigue behavior of Fe-Cr-Ni-based metastable austenitic steels with an identical tensile strength and different solute carbon contents

Takuro Ogawa, Motomichi Koyama, Yuri Nishikura, Kaneaki Tsuzaki, Hiroshi Noguchi

ISIJ International　58　1910-1919　2018年10月1日

DOI： 10.2355/isijinternational.ISIJINT-2018-098 　

ISSN：0915-1559

Surface orientation dependence of hydrogen flux in lenticular martensite of an Fe-Ni-C alloy clarified through in situ silver decoration technique 査読有り

Motomichi Koyama, Daisuke Yamasaki, Kaneaki Tsuzaki

Materials Letters　228　273-276　2018年10月1日

DOI： 10.1016/j.matlet.2018.06.022 　

ISSN：1873-4979 0167-577X

Effect of state of carbon on fatigue properties and dislocation structure of Fe-0.017mass%C alloy 査読有り

Nobuyuki Yoshimura, Kohsaku Ushioda, Yuichi Yoshida, Eisaku Sakurada, Mitsuharu Yonemura, Motomichi Koyama, Hiroshi Noguchi, Chihiro Watanabe

Materials Science and Engineering A　732　212-219　2018年8月8日

DOI： 10.1016/j.msea.2018.06.082 　

ISSN：0921-5093

Microstructural mechanisms of fatigue crack non-propagation in TRIP-maraging steels 査読有り

Z. Zhang, M. Koyama, M. M. Wang, K. Tsuzaki, C. C. Tasan, H. Noguchi

International Journal of Fatigue　113　126-136　2018年8月1日

DOI： 10.1016/j.ijfatigue.2018.04.013 　

ISSN：0142-1123

Non-propagating fatigue cracks in austenitic steels with a micro-notch: Effects of dynamic strain aging, martensitic transformation, and microstructural hardness heterogeneity 査読有り

Yuri Nishikura, Motomichi Koyama, Yusuke Yamamura, Takuro Ogawa, Kaneaki Tsuzaki, Hiroshi Noguchi

International Journal of Fatigue　113　359-366　2018年8月1日

DOI： 10.1016/j.ijfatigue.2018.04.027 　

ISSN：0142-1123

Ductile-to-brittle transition in tensile failure due to shear-affected zone with a stress-concentration source: a comparative study on punched-plate tensile-failure characteristics of precipitation-hardened and dual-phase steels 査読有り

Hamada Shigeru, Zhang Jiwang, Zhang Kejin, Koyama Motomichi, Tsuchiyama Toshihiro, Yokoi Tatsuo, Noguchi Hiroshi

INTERNATIONAL JOURNAL OF FRACTURE　212　(2)　237-248　2018年8月

DOI： 10.1007/s10704-018-0304-9 　

ISSN：0376-9429

On the Utility of Crystal Plasticity Modeling to Uncover the Individual Roles of Microdeformation Mechanisms on the Work Hardening Response of Fe-23Mn-0.5C TWIP Steel in the Presence of Hydrogen

B. Bal, M. Koyama, D. Canadinc, G. Gerstein, H. J. Maier, K. Tsuzaki

Journal of Engineering Materials and Technology, Transactions of the ASME　140　(3)　2018年7月1日

DOI： 10.1115/1.4038801 　

ISSN：1528-8889 0094-4289

Comparative study of hydrogen embrittlement in stable and metastable high-entropy alloys 査読有り

Kenshiro Ichii, Motomichi Koyama, Cemal Cem Tasan, Kaneaki Tsuzaki

Scripta Materialia　150　74-77　2018年6月1日

DOI： 10.1016/j.scriptamat.2018.03.003 　

ISSN：1359-6462

Temperature dependence of transgranular fatigue crack resistance in interstitial-free steel and Fe-C steels with supersaturated carbon: Effects of dynamic strain aging and dynamic precipitation 査読有り

Bochuan Li, Motomichi Koyama, Eisaku Sakurada, Nobuyuki Yoshimura, Kohsaku Ushioda, Hiroshi Noguchi

International Journal of Fatigue　110　1-9　2018年5月1日

DOI： 10.1016/j.ijfatigue.2018.01.003 　

ISSN：0142-1123

Fe-Mn-Cオーステナイト鋼における動的ひずみ時効と関連現象 査読有り

小山元道, 澤口孝宏, 津﨑兼彰

鉄と鋼　104　(4)　187-200　2018年4月1日

DOI： 10.2355/tetsutohagane.TETSU-2017-089 　

ISSN：0021-1575

Microstructural hardness heterogeneity triggers fatigue crack non-propagation in as-hot-rolled Fe-30Mn-3Si-3Al twinning-induced plasticity steel 査読有り

Motomichi Koyama, Yusuke Yamamura, Takahiro Sawaguchi, Kaneaki Tsuzaki, Hiroshi Noguchi

International Journal of Fatigue　108　18-24　2018年3月1日

DOI： 10.1016/j.ijfatigue.2017.11.009 　

ISSN：0142-1123

High-concentration carbon assists plasticity-driven hydrogen embrittlement in a Fe-high Mn steel with a relatively high stacking fault energy 査読有り

Ibrahim Burkay Tuğluca, Motomichi Koyama, Burak Bal, Demircan Canadinc, Eiji Akiyama, Kaneaki Tsuzaki

Materials Science and Engineering A　717　78-84　2018年2月21日

DOI： 10.1016/j.msea.2018.01.087 　

ISSN：0921-5093

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-4V Alloy

M. Koyama, Y. Tanaka, K. Tsuzaki

Experimental Mechanics　58　(2)　381-386　2018年2月1日

DOI： 10.1007/s11340-017-0336-5 　

ISSN：1741-2765 0014-4851

Hydrogen-assisted failure in a bimodal twinning-induced plasticity steel: Delamination events and damage evolution 査読有り

Abbas Mohammadi, Motomichi Koyama, Gregory Gerstein, Hans Jürgen Maier, Hiroshi Noguchi

International Journal of Hydrogen Energy　43　(4)　2492-2502　2018年1月25日

DOI： 10.1016/j.ijhydene.2017.11.177 　

ISSN：0360-3199

Visualization of dislocations through electron channeling contrast imaging at fatigue crack tip, interacting with pre-existing dislocations

Kishan Habib, Motomichi Koyama, Toshihiro Tsuchiyama, Hiroshi Noguchi

Materials Research Letters　6　(1)　61-66　2018年1月2日

DOI： 10.1080/21663831.2017.1392370 　

ISSN：2166-3831

Influence of shear-affected-zone due to punching on tensile characteristics of steel plate

Kejin Zhang, Shigeru Hamada, Motomichi Koyama, Tatsuo Yokoi, Hiroshi Noguchi

Procedia Structural Integrity　13　1047-1052　2018年1月1日

DOI： 10.1016/j.prostr.2018.12.196 　

Re-examination of fatigue crack propagation mechanism under cyclic Mode II loading

Shigeru Hamada, Taro Suemasu, Motomichi Koyama, Masaharu Ueda, Hiroshi Noguchi

Procedia Structural Integrity　13　1026-1031　2018年1月1日

DOI： 10.1016/j.prostr.2018.12.191 　

Crystallographic orientation-dependent growth mode of microstructurally fatigue small crack in a laminated Ti-6Al-4V alloy

Akira Maenosono, Motomichi Koyama, Yoshihisa Tanaka, Shien Ri, Qinghu Wang, Hiroshi Noguchi

Procedia Structural Integrity　13　694-699　2018年1月1日

DOI： 10.1016/j.prostr.2018.12.115 　

ISSN：2452-3216

Optical microscopy-Based damage quantification: an example of cryogenic deformation of a dual-Phase steel

Nao Uehata, Motomichi Koyama, Shusaku Takagi, Kaneaki Tsuzaki

ISIJ International　58　(1)　179-185　2018年

DOI： 10.2355/isijinternational.ISIJINT-2017-468 　

ISSN：0915-1559

Proposal and verification of novel fatigue crack propagation simulation method by finite element method. 査読有り

Structural Integrity Procedia　2018年

Analysis of fatigue crack configuration influence on fatigue life. 査読有り

Structural Integrity Procedia　2018年

Quantification method for parameters affecting multi-scale roughness-induced fatigue crack closure. 査読有り

Structural Integrity Procedia　2018年

The influence of fracture surface contact in fatigue crack propagation of material having texture under Mode II loading. 査読有り

Structural Integrity Porcedia　2018年

Fatigue crack growth behavior and associated microstructure in a metastable high-entropy alloy. 査読有り

Structural Integrity Procedia　2018年

Strain rate sensitivity of microstructural damage evolution in a dual-phase steel pre-charged with hydrogen. 査読有り

Structural Integrity Procedia　2018年

Localized plasticity and associated cracking in stable and metastable high-entropy alloys pre-charged with hydrogen. 査読有り

Structural Integrity Procedia　2018年

Small fatigue crack growth in a high entropy alloy. 査読有り

Structural Integrity Procedia　2018年

Proposal of fractographic analysis method coupled with EBSD and ECCI. 査読有り

2018年

Effect of Si on temperature dependence of non-propagation limit of small fatigue crack in a Fe-C alloy. 査読有り

Structural Integrity Procedia　2018年

A new design concept for prevention of hydrogen-induced mechanical degradation: viewpoints of metastability and high entropy. 査読有り

Structural Integrity Procedia　2018年

Cooling and deformation-induced hydrogen desorption in metastable austenitic steels detected by mass spectroscopy. 査読有り

Conference proceedings　J03　2018年

同引張強度かつ異なる固溶炭素量を有するFe-Cr-Ni 基準安定オーステナイトステンレス鋼の疲労挙動 査読有り

小川 卓郎, 小山 元道, 西倉 優理, 津﨑 兼彰, 野口 博司

鉄 と 鋼 Tetsu-to-Hagané　104　(2)　88-97　2018年

DOI： 10.2355/tetsutohagane.TETSU-2017-058 　

ISSN：0021-1575

応力再分配効果が水素助長疲労き裂進展に及ぼす影響 査読有り

佐々木 大輔, 小山 元道, 野口 博司

鉄 と 鋼 Tetsu-to-Hagané　104　(1)　46-53　2018年

DOI： 10.2355/tetsutohagane.TETSU-2017-050 　

ISSN：0021-1575

Interstitial carbon enhanced corrosion resistance of Fe-33Mn-xC austenitic steels: Inhibition of anodic dissolution 査読有り

Aya Chiba, Motomichi Koyama, Eiji Akiyama, Toshiyasu Nishimura

Journal of the Electrochemical Society　165　(2)　C19-C26　2018年

DOI： 10.1149/2.0661802jes 　

ISSN：1945-7111 0013-4651

eISSN：1945-7111

Overview of Dynamic Strain Aging and Associated Phenomena in Fe-Mn-C Austenitic Steels 査読有り

Koyama Motomichi, Sawaguchi Takahiro, Tsuzaki Kaneaki

ISIJ INTERNATIONAL　58　(8)　1383-1395　2018年

DOI： 10.2355/isijinternational.ISIJINT-2018-237 　

ISSN：0915-1559

Split and Shift of epsilon-martensite Peak in an X-ray Diffraction Profile during Hydrogen Desorption: A Geometric Effect of Atomic Sequence 査読有り

Koyama Motomichi, Abe Yuji, Tsuzaki Kaneaki

ISIJ INTERNATIONAL　58　(9)　1745-1747　2018年

DOI： 10.2355/isijinternational.ISIJINT-2018-260 　

ISSN：0915-1559

Microstructural damage evolution and arrest in binary Fe-high-Mn alloys with different deformation temperatures. 査読有り

International Journal of Fracture　213　(2)　193-206　2018年

DOI： 10.1007/s10704-018-0307-6 　

Room-temperature blue brittleness of Fe-Mn-C austenitic steels 査読有り

Motomichi Koyama, Yusaku Shimomura, Aya Chiba, Eiji Akiyama, Kaneaki Tsuzaki

SCRIPTA MATERIALIA　141　20-23　2017年12月

DOI： 10.1016/j.scriptamat.2017.07.017 　

ISSN：1359-6462

Reply to comments on the paper "In situ observations of silver-decoration evolution under hydrogen permeation: Effects of grain boundary misorientation on hydrogen flux in pure iron" by Gavriljuk and Teus 査読有り

Motomichi Koyama, Daisuke Yamasaki, Kaneald Tsuzaki

SCRIPTA MATERIALIA　140　91-92　2017年11月

DOI： 10.1016/j.scriptamat.2017.07.019 　

ISSN：1359-6462

Fatigue crack non-propagation assisted by nitrogen-enhanced dislocation planarity in austenitic stainless steels 査読有り

Kishan Habib, Motomichi Koyama, Toshihiro Tsuchiyama, Hiroshi Noguchi

INTERNATIONAL JOURNAL OF FATIGUE　104　158-170　2017年11月

DOI： 10.1016/j.ijfatigue.2017.07.019 　

ISSN：0142-1123

eISSN：1879-3452

Effects of epsilon-martensitic transformation on crack tip deformation, plastic damage accumulation, and slip plane cracking associated with low-cycle fatigue crack growth 査読有り

Yun-Byum Ju, Motomichi Koyama, Takahiro Sawaguchi, Kaneaki Tsuzaki, Hiroshi Noguchi

INTERNATIONAL JOURNAL OF FATIGUE　103　533-545　2017年10月

DOI： 10.1016/j.ijfatigue.2017.06.040 　

ISSN：0142-1123

eISSN：1879-3452

Hydrogen desorption and cracking associated with martensitic transformation in Fe-Cr-Ni-Based austenitic steels with different carbon contents 査読有り

Motomichi Koyama, Takuro Ogawa, Dingshun Yan, Yuya Matsumoto, Cemal Cem Tasan, Kenichi Takai, Kaneaki Tsuzaki

INTERNATIONAL JOURNAL OF HYDROGEN ENERGY　42　(42)　26423-26435　2017年10月

DOI： 10.1016/j.ijhydene.2017.08.209 　

ISSN：0360-3199

eISSN：1879-3487

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 査読有り

M. Koyama, Y. Tanaka, K. Tsuzaki

Experimental Mechanics　58　381-386　2017年9月

Threshold stress intensity factor range of a mechanically-long and microstructually-short crack perpendicular to an interface with plastic mismatch 査読有り

Bochuan Li, Motomichi Koyama, Shigeru Hamada, Hiroshi Noguchi

ENGINEERING FRACTURE MECHANICS　182　287-302　2017年9月

DOI： 10.1016/j.engfracmech.2017.07.023 　

ISSN：0013-7944

eISSN：1873-7315

Material property controlling non-propagating fatigue crack length of mechanically and physically short-crack based on Dugdale-model analysis 査読有り

Naoki Fukumura, Bochuan Li, Motomichi Koyama, Tomohiro Suzuki, Shigeru Hamada, Kaneaki Tsuzaki, Hiroshi Noguchi

THEORETICAL AND APPLIED FRACTURE MECHANICS　90　193-202　2017年8月

DOI： 10.1016/j.tafmec.2017.04.012 　

ISSN：0167-8442

eISSN：1872-7638

Effects of martensitic transformability and dynamic strain age hardenability on plasticity in metastable austenitic steels containing carbon 査読有り

Takuro Ogawa, Motomichi Koyama, Cemal Cem Tasan, Kaneaki Tsuzaki, Hiroshi Noguchi

JOURNAL OF MATERIALS SCIENCE　52　(13)　7868-7882　2017年7月

DOI： 10.1007/s10853-017-1052-3 　

ISSN：0022-2461

eISSN：1573-4803

Characteristics of hydrogen-assisted intergranular fatigue crack growth in interstitial-free steel: role of plastic strain localization 査読有り

Motomichi Koyama, Yosuke Onishi, Hiroshi Noguchi

INTERNATIONAL JOURNAL OF FRACTURE　206　(1)　123-130　2017年7月

DOI： 10.1007/s10704-017-0205-3 　

ISSN：0376-9429

eISSN：1573-2673

Effect of the state of carbon on ductility in Fe-0.017mass%C ferritic steel 査読有り

Nobuyuki Yoshimura, Kohsaku Ushioda, Mitsuharu Yonemura, Motomichi Koyama, Masaki Tanaka, Hiroshi Noguchi

MATERIALS SCIENCE AND ENGINEERING A-STRUCTURAL MATERIALS PROPERTIES MICROSTRUCTURE AND PROCESSING　701　120-128　2017年7月

DOI： 10.1016/j.msea.2017.06.070 　

ISSN：0921-5093

eISSN：1873-4936

Effects of lamella size and connectivity on fatigue crack resistance of TRIP-maraging steel

Z. Zhang, M. Koyama, M. M. Wang, K. Tsuzaki, C. C. Tasan, H. Noguchi

INTERNATIONAL JOURNAL OF FATIGUE　100　176-186　2017年7月

DOI： 10.1016/j.ijfatigue.2017.03.040 　

ISSN：0142-1123

eISSN：1879-3452

Impact of Mn-C couples on fatigue crack growth in austenitic steels: Is the attractive atomic interaction negative or positive? 査読有り

Kishan Habib, Motomichi Koyama, Hiroshi Noguchi

INTERNATIONAL JOURNAL OF FATIGUE　99　1-12　2017年6月

DOI： 10.1016/j.ijfatigue.2017.02.009 　

ISSN：0142-1123

eISSN：1879-3452

Multiscale in situ deformation experiments: A sequential process from strain localization to failure in a laminated Ti-6Al-4V alloy 査読有り

Motomichi Koyama, Keita Yamanouchi, Qinghua Wang, Shien Ri, Yoshihisa Tanaka, Yasuaki Hamano, Shigeto Yamasaki, Masatoshi Mitsuhara, Masataka Ohkubo, Hiroshi Noguchi, Kaneaki Tsuzaki

MATERIALS CHARACTERIZATION　128　217-225　2017年6月

DOI： 10.1016/j.matchar.2017.04.010 　

ISSN：1044-5803

eISSN：1873-4189

Two-dimensional Moire phase analysis for accurate strain distribution measurement and application in crack prediction 査読有り

Qinghua Wang, Shien Ri, Hiroshi Tsuda, Motomichi Koyama, Kaneaki Tsuzaki

OPTICS EXPRESS　25　(12)　13465-13480　2017年6月

DOI： 10.1364/OE.25.013465 　

ISSN：1094-4087

Underlying interstitial carbon concentration dependence of transgranular fatigue crack resistance in Fe-C ferritic steels: The kinetic effect viewpoint 査読有り

Bochuan Li, Motomichi Koyama, Eisaku Sakurada, Nobuyuki Yoshimura, Kohsaku Ushioda, Hiroshi Noguchi

INTERNATIONAL JOURNAL OF FATIGUE　98　101-110　2017年5月

DOI： 10.1016/j.ijfatigue.2017.01.029 　

ISSN：0142-1123

eISSN：1879-3452

Overview of hydrogen embrittlement in high-Mn steels 査読有り

Motomichi Koyama, Eiji Akiyama, Young-Kook Lee, Dierk Raabe, Kaneaki Tsuzaki

INTERNATIONAL JOURNAL OF HYDROGEN ENERGY　42　(17)　12706-12723　2017年4月

DOI： 10.1016/j.ijhydene.2017.02.214 　

ISSN：0360-3199

eISSN：1879-3487

Interfacial hydrogen localization in austenite/martensite dual-phase steel visualized through optimized silver decoration and scanning Kelvin probe force microscopy 査読有り

T. Nagashima, M. Koyama, A. Bashir, M. Rohwerder, C. C. Tasan, E. Akiyama, D. Raabe, K. Tsuzaki

MATERIALS AND CORROSION-WERKSTOFFE UND KORROSION　68　(3)　306-310　2017年3月

DOI： 10.1002/maco.201609104 　

ISSN：0947-5117

eISSN：1521-4176

In situ observations of silver-decoration evolution under hydrogen permeation: Effects of grain boundary misorientation on hydrogen flux in pure iron 査読有り

Motomichi Koyama, Daisuke Yamasaki, Tatsuya Nagashima, Cemal Cem Tasan, Kaneaki Tsuzaki

SCRIPTA MATERIALIA　129　48-51　2017年3月

DOI： 10.1016/j.scriptamat.2016.10.027 　

ISSN：1359-6462

Generalized evaluation method for determining transition crack length for microstructurally small to microstructurally large fatigue crack growth: Experimental definition, facilitation, and validation 査読有り

Toshinobu Omura, Motomichi Koyama, Yasuaki Hamano, Kaneaki Tsuzaki, Hiroshi Noguchi

INTERNATIONAL JOURNAL OF FATIGUE　95　38-44　2017年2月

DOI： 10.1016/j.ijfatigue.2016.10.010 　

ISSN：0142-1123

eISSN：1879-3452

Mechanical-probabilistic evaluation of size effect of fatigue life using data obtained from single smooth specimen: An example using Fe-30Mn-4Si-2Al seismic damper alloy 査読有り

Motomichi Koyama, Huichao Li, Yasuaki Hamano, Takahiro Sawaguchi, Kaneaki Tsuzaki, Hiroshi Noguchi

ENGINEERING FAILURE ANALYSIS　72　34-47　2017年2月

DOI： 10.1016/j.engfailanal.2016.11.015 　

ISSN：1350-6307

eISSN：1873-1961

Study on crack occurrence of titanium alloy in tensile test by advanced moiré technique

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　2017年1月1日

Hydrogen embrittlement of binary high Mn austenitic steels

Motomichi Koyama, Takahiro Sawaguchi, Kaneaki Tsuzaki

ICF 2017 - 14th International Conference on Fracture　1　75-76　2017年1月1日

Visualization of strain concentrations in composites using advanced image processing techniques

Q. Wang, S. Ri, Y. Tanaka, M. Koyama

ICCM International Conferences on Composite Materials　2017-August　2017年1月1日

Investigation on Mode I propagation behavior of fatigue crack in precipitation-hardened aluminum alloy with different Mg content

S. F. Anis, M. Koyama, H. Noguchi

Materials Science Forum　889　143-147　2017年

DOI： 10.4028/www.scientific.net/MSF.889.143 　

ISSN：0255-5476

鉄鋼材料の疲労における固溶炭素の役割と潜在能力 査読有り

小山元道

まてりあ　56　(7)　458-461　2017年

DOI： 10.2320/materia.56.458 　

ISSN：1340-2625

Fe-Cフェライト二元合金におけるコーキシング効果発現因子： ひずみ時効現象に注目して 査読有り

小山 元道, 任 博泓, 吉村 信幸, 桜田 栄作, 潮田 浩作, 野口 博司

鉄 と 鋼 Tetsu-to-Hagané　103　(11)　660-666　2017年

Comparative study on small fatigue crack propagation between Fe-30Mn-3Si-3Al and Fe-23Mn-0.5C twinning-induced plasticity steels: Aspects of non-propagation of small fatigue cracks 査読有り

Motomichi Koyama, Yusuke Yamamura, Rinqing Che, Takahiro Sawaguchi, Kaneaki Tsuzaki, Hiroshi Noguchi

INTERNATIONAL JOURNAL OF FATIGUE　94　1-5　2017年1月

DOI： 10.1016/j.ijfatigue.2016.09.003 　

ISSN：0142-1123

eISSN：1879-3452

Intrinsic Factors that Trigger the Coaxing Effect in Binary Fe-C Ferritic Alloys with a Focus on Strain Aging 査読有り

Motomichi Koyama, Bohong Ren, Nobuyuki Yoshimura, Eisaku Sakurada, Kohsaku Ushioda, Hiroshi Noguchi

ISIJ INTERNATIONAL　57　(2)　358-364　2017年

DOI： 10.2355/isijinternational.ISIJINT-2016-513 　

ISSN：0915-1559

eISSN：1347-5460

Recent progress in microstructural hydrogen mapping in steels: quantification, kinetic analysis, and multi-scale characterisation 査読有り

Motomichi Koyama, Michael Rohwerder, Cemal Cem Tasan, Asif Bashir, Eiji Akiyama, Kenichi Takai, Dierk Raabe, Kaneaki Tsuzaki

MATERIALS SCIENCE AND TECHNOLOGY　33　(13)　1481-1496　2017年

DOI： 10.1080/02670836.2017.1299276 　

ISSN：0267-0836

eISSN：1743-2847

Intrinsic Factors That Trigger the Coaxing Effect in Binary Fe-C Ferritic Alloys with a Focus on Strain Aging

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　(11)　52-58　2017年

DOI： 10.2355/tetsutohagane.TETSU-2017-043 　

ISSN：0021-1575

eISSN：1883-2954

Effect of strain rate on hydrogen embrittlement susceptibility of twinning-induced plasticity steel pre-charged with high-pressure hydrogen gas 査読有り

B. Bal, M. Koyama, G. Gerstein, H. J. Maier, K. Tsuzaki

INTERNATIONAL JOURNAL OF HYDROGEN ENERGY　41　(34)　15362-15372　2016年9月

DOI： 10.1016/j.ijhydene.2016.06.259 　

ISSN：0360-3199

eISSN：1879-3487

Martensitic transformation-induced hydrogen desorption characterized by utilizing cryogenic thermal desorption spectroscopy during cooling 査読有り

Motomichi Koyama, Yuji Abe, Kei Saito, Eiji Akiyama, Kenichi Takai, Kaneaki Tsuzaki

SCRIPTA MATERIALIA　122　50-53　2016年9月

DOI： 10.1016/j.scriptamat.2016.05.012 　

ISSN：1359-6462

Potential resistance to transgranular fatigue crack growth of Fe-C alloy with a supersaturated carbon clarified through FIB micro-notching technique 査読有り

Bochuan Li, Motomichi Koyama, Eisaku Sakurada, Nobuyuki Yoshimura, Kohsaku Ushioda, Hiroshi Noguchi

INTERNATIONAL JOURNAL OF FATIGUE　87　1-5　2016年6月

DOI： 10.1016/j.ijfatigue.2016.01.003 　

ISSN：0142-1123

eISSN：1879-3452

Hydrogen Embrittlement Susceptibility of Fe-Mn Binary Alloys with High Mn Content: Effects of Stable and Metastable epsilon-Martensite, and Mn Concentration 査読有り

Motomichi Koyama, Shota Okazaki, Takahiro Sawaguchi, Kaneaki Tsuzaki

METALLURGICAL AND MATERIALS TRANSACTIONS A-PHYSICAL METALLURGY AND MATERIALS SCIENCE　47A　(6)　2656-2673　2016年6月

DOI： 10.1007/s11661-016-3431-9 　

ISSN：1073-5623

eISSN：1543-1940

In situ microscopic observations of low-cycle fatigue-crack propagation in high-Mn austenitic alloys with deformation-induced epsilon-martensitic transformation 査読有り

Yun-Byum Ju, Motomichi Koyama, Takahiro Sawaguchi, Kaneaki Tsuzaki, Hiroshi Noguchi

ACTA MATERIALIA　112　326-336　2016年6月

DOI： 10.1016/j.actamat.2016.04.042 　

ISSN：1359-6454

eISSN：1873-2453

Elucidation of the effects of cementite morphology on damage formation during monotonic and cyclic tension in binary low carbon steels using in situ characterization 査読有り

Motomichi Koyama, Yachen Yu, Jia-Xi Zhou, Nobuyuki Yoshimura, Eisaku Sakurada, Kohsaku Ushioda, Hiroshi Noguchi

MATERIALS SCIENCE AND ENGINEERING A-STRUCTURAL MATERIALS PROPERTIES MICROSTRUCTURE AND PROCESSING　667　358-367　2016年6月

DOI： 10.1016/j.msea.2016.05.029 　

ISSN：0921-5093

eISSN：1873-4936

Hexagonal close-packed Martensite-related Fatigue Crack Growth under the Influence of Hydrogen: Example of Fe-15Mn-10Cr-8Ni-4Si Austenitic Alloy 査読有り

Kaneaki Tsuzaki, Koki Fukuda, Motomichi Koyama, Hisao Matsunaga

SCRIPTA MATERIALIA　113　6-9　2016年3月

DOI： 10.1016/j.scriptamat.2015.10.016 　

ISSN：1359-6462

水素助長き裂進展に及ぼすパーライトの抑制効果

佐々木 大輔, 小山 元道, 野口 博司

年次大会　2016　S0310404　2016年

DOI： 10.1299/jsmemecj.2016.s0310404 　

eISSN：2424-2667

炭素拡散の速度論と積層欠陥の幾何学：γ鋼の”室温”ひずみ時効現象理解に向けて 査読有り

小山元道

ふぇらむ（私の論文）　21　(4)　186-189　2016年

ISSN：1341-688X

水焼入れFe-Cフェライト鋼における粒界き裂発生および微小き裂進展挙動 査読有り

小山元道, 周佳義, 吉田裕一, 吉村信幸, 潮田浩作, 野口博司

鉄と鋼　102　(5)　268-273　2016年

DOI： 10.2355/tetsutohagane.TETSU-2015-108 　

ISSN：0021-1575

eISSN：1883-2954

Hydrogen-assisted damage in austenite/martensite dual-phase steel 査読有り

Motomichi Koyama, Cemal Cem Tasan, Tatsuya Nagashima, Eiji Akiyama, Dierk Raabe, Kaneaki Tsuzaki

PHILOSOPHICAL MAGAZINE LETTERS　96　(1)　9-18　2016年1月

DOI： 10.1080/09500839.2015.1130275 　

ISSN：0950-0839

eISSN：1362-3036

ひずみ・微細組織・き裂/ボイドのマルチスケール観察による鉄鋼の損傷発達機構解析：εマルテンサイトが関与する損傷発達の場合 査読有り

Kaneko Takahiro, Koyama Motomichi, Fujisawa Tomoya, Tsuzaki Kaneaki

鉄と鋼　102　(5)　227-236　2016年

DOI： 10.2355/tetsutohagane.TETSU-2015-081 　

ISSN：0021-1575

eISSN：1883-2954

Characteristic Fatigue Crack Growth Behavior of Low Carbon Steel under Low-pressure Hydrogen Gas Atmosphere in an Ultra-low Frequency 査読有り

Yosuke Onishi, Motomichi Koyama, Daisuke Sasaki, Hiroshi Noguchi

ISIJ INTERNATIONAL　56　(5)　855-860　2016年

DOI： 10.2355/isijinternational.ISIJINT-2015-647 　

ISSN：0915-1559

eISSN：1347-5460

Notch Sensitivity of the Fatigue Limit in High-Strength Steel 査読有り

Yasuaki Hamano, Motomichi Koyama, Shigeru Hamada, Hiroshi Noguchi

ISIJ INTERNATIONAL　56　(8)　1480-1486　2016年

DOI： 10.2355/isijinternational.ISIJINT-2015-744 　

ISSN：0915-1559

eISSN：1347-5460

Suppression Mechanism of Strain-age-hardening in Carbon Steel Associated with Hydrogen Uptake 査読有り

Takuro Ogawa, Motomichi Koyama, Hiroshi Noguchi

ISIJ INTERNATIONAL　56　(9)　1656-1661　2016年

DOI： 10.2355/isijinternational.ISIJINT-2016-063 　

ISSN：0915-1559

eISSN：1347-5460

Combined Multi-scale Analyses on Strain/Damage/Microstructure in Steel: Example of Damage Evolution Associated with epsilon-martensitic Transformation 査読有り

Takahiro Kaneko, Motomichi Koyama, Tomoya Fujisawa, Kaneaki TsuzakI'

ISIJ INTERNATIONAL　56　(11)　2037-2046　2016年

DOI： 10.2355/isijinternational.ISIJINT-2016-272 　

ISSN：0915-1559

eISSN：1347-5460

Enhancing Hydrogen Embrittlement Resistance of Lath Martensite by Introducing Nano-Films of Interlath Austenite 査読有り

Meimei Wang, C. Cem Tasan, Motomichi Koyama, Dirk Ponge, Dierk Raabe

METALLURGICAL AND MATERIALS TRANSACTIONS A-PHYSICAL METALLURGY AND MATERIALS SCIENCE　46A　(9)　3797-3802　2015年9月

DOI： 10.1007/s11661-015-3009-y 　

ISSN：1073-5623

eISSN：1543-1940

Positive and negative effects of hydrogen on tensile behavior in polycrystalline Fe-30Mn-(6-x)Si-xAl austenitic alloys 査読有り

Kensuke Yamada, Motomichi Koyama, Takahiro Kaneko, Kaneaki Tsuzaki

SCRIPTA MATERIALIA　105　54-57　2015年8月

DOI： 10.1016/j.scriptamat.2015.05.007 　

ISSN：1359-6462

Effects of hydrogen-altered yielding and work hardening on plastic-zone evolution: A finite-element analysis 査読有り

Daisuke Sasaki, Motomichi Koyama, Kenji Higashida, Kaneaki Tsuzaki, Hiroshi Noguchi

INTERNATIONAL JOURNAL OF HYDROGEN ENERGY　40　(31)　9825-9837　2015年8月

DOI： 10.1016/j.ijhydene.2015.05.187 　

ISSN：0360-3199

eISSN：1879-3487

Factors affecting hydrogen-assisted cracking in a commercial tempered martensitic steel: Mn segregation, MnS, and the stress state around abnormal cracks 査読有り

Daisuke Sasaki, Motomichi Koyama, Hiroshi Noguchi

MATERIALS SCIENCE AND ENGINEERING A-STRUCTURAL MATERIALS PROPERTIES MICROSTRUCTURE AND PROCESSING　640　72-81　2015年7月

DOI： 10.1016/j.msea.2015.05.083 　

ISSN：0921-5093

eISSN：1873-4936

Effects of cementite morphology on short-fatigue-crack propagation in binary Fe-C steel 査読有り

Zhou-Jia Xi, Motomichi Koyama, Yuichi Yoshida, Nobuyuki Yoshimura, Kohsaku Ushioda, Hiroshi Noguchi

PHILOSOPHICAL MAGAZINE LETTERS　95　(7)　384-391　2015年7月

DOI： 10.1080/09500839.2015.1076174 　

ISSN：0950-0839

eISSN：1362-3036

Importance of crack-propagation-induced epsilon-martensite in strain-controlled low-cycle fatigue of high-Mn austenitic steel 査読有り

Huichao Li, Motomichi Koyama, Takahiro Sawaguchi, Kaneaki Tsuzaki, Hiroshi Noguchi

PHILOSOPHICAL MAGAZINE LETTERS　95　(6)　303-311　2015年6月

DOI： 10.1080/09500839.2015.1052029 　

ISSN：0950-0839

eISSN：1362-3036

Tensile properties of precracked tempered martensitic steel specimens tested at ultralow strain rates in high-pressure hydrogen atmosphere 査読有り

Daisuke Sasaki, Motomichi Koyama, Shigeru Hamada, Hiroshi Noguchi

PHILOSOPHICAL MAGAZINE LETTERS　95　(5)　260-268　2015年5月

DOI： 10.1080/09500839.2015.1049574 　

ISSN：0950-0839

eISSN：1362-3036

An Overview of Dual-Phase Steels: Advances in Microstructure-Oriented Processing and Micromechanically Guided Design 査読有り

C. C. Tasan, M. Diehl, D. Yan, M. Bechtold, F. Roters, L. Schemmann, C. Zheng, N. Peranio, D. Ponge, M. Koyama, K. Tsuzaki, D. Raabe

ANNUAL REVIEW OF MATERIALS RESEARCH, VOL 45　45　391-431　2015年

DOI： 10.1146/annurev-matsci-070214-021103 　

ISSN：1531-7331

Influences of ε martensite and Mn concentration o hydrogen uptake and desorption in Fe-high Mn vinary alloys by cryogenic thermal desorption analysis. 査読有り

ISIJ International　55　2269-2271　2015年

高Mnオーステナイト合金における引張特性に及ぼすSiの効果：変形誘起εマルテンサイト変態に関連して 査読有り

小山元道, 澤口孝宏, 津﨑兼彰

日本金属学会誌　79　(12)　657-663　2015年

DOI： 10.2320/jinstmet.J2015047 　

ISSN：0021-4876

eISSN：1880-6880

高強度鋼の疲労限度における切欠き敏感性について 査読有り

濱野泰明, 小山元道, 濱田繁, 野口博司

鉄と鋼　101　(10)　552-558　2015年

DOI： 10.2355/tetsutohagane.TETSU-2015-045 　

ISSN：0021-1575

eISSN：1883-2954

水素侵入に起因する炭素鋼のひずみ時効硬化抑制機構 査読有り

小川卓郎, 小山元道, 佐々木大輔, 野口博司

鉄と鋼　101　(10)　546-551　2015年

DOI： 10.2355/tetsutohagane.TETSU-2015-033 　

ISSN：0021-1575

eISSN：1883-2954

Detection of Charged Hydrogen in Ferritic Steel through Cryogenic Secondary Ion Mass Spectrometry 査読有り

Atsushi Nishimoto, Motomichi Koyama, Shigeru Yamato, Yasuji Oda, Tohru Awane, Hiroshi Noguchi

ISIJ INTERNATIONAL　55　(1)　335-337　2015年

DOI： 10.2355/isijinternational.55.335 　

ISSN：0915-1559

eISSN：1347-5460

Effects of Si on Tensile Properties Associated with Deformation-Induced epsilon-Martensitic Transformation in High Mn Austenitic Alloys 査読有り

Motomichi Koyama, Takahiro Sawaguchi, Kaneaki Tsuzaki

MATERIALS TRANSACTIONS　56　(6)　819-825　2015年

DOI： 10.2320/matertrans.M2015042 　

ISSN：1345-9678

eISSN：1347-5320

Deformation Twinning Behavior of Twinning-induced Plasticity Steels with Different Carbon Concentrations - Part 1: Atomic Force Microscopy and Electron Backscatter Diffraction Measurements 査読有り

Motomichi Koyama, Takahiro Sawaguchi, Kaneaki Tsuzaki

ISIJ INTERNATIONAL　55　(8)　1747-1753　2015年

DOI： 10.2355/isijinternational.ISIJINT-2015-069 　

ISSN：0915-1559

eISSN：1347-5460

Deformation Twinning Behavior of Twinning-induced Plasticity Steels with Different Carbon Concentrations - Part 2: Proposal of Dynamic-strain-aging-assisted Deformation Twinning 査読有り

Motomichi Koyama, Takahiro Sawaguchi, Kaneaki Tsuzaki

ISIJ INTERNATIONAL　55　(8)　1754-1761　2015年

DOI： 10.2355/isijinternational.ISIJINT-2015-070 　

ISSN：0915-1559

eISSN：1347-5460

Spatially and Kinetically Resolved Mapping of Hydrogen in a Twinning-Induced Plasticity Steel by Use of Scanning Kelvin Probe Force Microscopy 査読有り

Motomichi Koyama, Asif Bashir, Michael Rohwerder, Sergiy V. Merzlikin, Eiji Akiyama, Kaneaki Tsuzaki, Dierk Raabe

JOURNAL OF THE ELECTROCHEMICAL SOCIETY　162　(12)　C638-C647　2015年

DOI： 10.1149/2.0131512jes 　

ISSN：0013-4651

eISSN：1945-7111

epsilon -&gt;gamma Reverse Transformation-induced Hydrogen Desorption and Mn Effect on Hydrogen Uptake in Fe-Mn Binary Alloys 査読有り

Motomichi Koyama, Kaneaki Tsuzaki

ISIJ INTERNATIONAL　55　(10)　2269-2271　2015年

DOI： 10.2355/isijinternational.ISIJINT-2015-215 　

ISSN：0915-1559

eISSN：1347-5460

極低周波数における低炭素鋼の低圧水素ガス環境下での特異な疲労き裂伝ぱ挙動 査読有り

Ohnishi Yosuke, Koyama Motomichi, Sasaki Daisuke, Noguchi Hiroshi

鉄と鋼　101　(11)　605-610　2015年

DOI： 10.2355/tetsutohagane.TETSU-2015-018 　

ISSN：0021-1575

eISSN：1883-2954

Intergranular Fatigue Crack Initiation and Its Associated Small Fatigue Crack Propagation in Water-quenched Fe-C Fully Ferritic Steel 査読有り

Motomichi Koyama, Zhou-Jia Xi, Yuichi Yoshida, Nobuyuki Yoshimura, Kohsaku Ushioda, Hiroshi Noguchi

ISIJ INTERNATIONAL　55　(11)　2463-2468　2015年

DOI： 10.2355/isijinternational.ISIJINT-2015-305 　

ISSN：0915-1559

eISSN：1347-5460

Strain mapping with high spatial resolution across a wide observation range by digital image correlation on plastic replicas 査読有り

Shigeru Hamada, Tomoya Fujisawa, Motomichi Koyama, Norimitsu Koga, Nobuo Nakada, Toshihiro Tsuchiyama, Masaharu Ueda, Hiroshi Noguchi

MATERIALS CHARACTERIZATION　98　140-146　2014年12月

DOI： 10.1016/j.matchar.2014.10.010 　

ISSN：1044-5803

eISSN：1873-4189

Alloy Design, Combinatorial Synthesis, and Microstructure-Property Relations for Low-Density Fe-Mn-Al-C Austenitic Steels 査読有り

D. Raabe, H. Springer, I. Gutierrez-Urrutia, F. Roters, M. Bausch, J. -B. Seol, M. Koyama, P. -P. Choi, K. Tsuzaki

JOM　66　(9)　1845-1856　2014年9月

DOI： 10.1007/s11837-014-1032-x 　

ISSN：1047-4838

eISSN：1543-1851

Hydrogen-assisted decohesion and localized plasticity in dual-phase steel 査読有り

Motomichi Koyama, Cemal Cem Tasan, Eiji Akiyama, Kaneaki Tsuzaki, Dierk Raabe

ACTA MATERIALIA　70　174-187　2014年5月

DOI： 10.1016/j.actamat.2014.01.048 　

ISSN：1359-6454

eISSN：1873-2453

Hydrogen embrittlement associated with strain localization in a precipitation-hardened Fe-Mn-Al-C light weight austenitic steel 査読有り

Motomichi Koyama, Hauke Springer, Sergiy V. Merzlikin, Kaneaki Tsuzaki, Eiji Akiyama, Dierk Raabe

INTERNATIONAL JOURNAL OF HYDROGEN ENERGY　39　(9)　4634-4646　2014年3月

DOI： 10.1016/j.ijhydene.2013.12.171 　

ISSN：0360-3199

eISSN：1879-3487

Factors affecting hydrogen embrittlement susceptibility of twinning-induced plasticity steels. 査読有り

Proc. 2nd HMnS　2014年

双晶誘起塑性鋼の双晶変形挙動に及ぼす炭素の影響ーPart 2:動的ひずみ時効の影響を考慮した双晶変形機構の提案ー 査読有り

小山元道, 澤口孝宏, 津﨑兼彰

鉄と鋼　100　(10)　1253-1260　2014年

DOI： 10.2355/tetsutohagane.100.1253 　

ISSN：0021-1575

eISSN：1883-2954

双晶誘起塑性鋼の双晶変形挙動に及ぼす炭素の影響ーPart 1:原子間力顕微鏡法と後方電子線散乱回析法を用いた解析ー 査読有り

小山元道, 澤口孝宏, 津﨑兼彰

鉄と鋼　100　(10)　1246-1252　2014年

DOI： 10.2355/tetsutohagane.100.1246 　

ISSN：0021-1575

eISSN：1883-2954

Fe-Mn-C-Al TWIP鋼の水素脆化における静的および動的ひずみ時効の影響 査読有り

小山元道, 秋山英二, 津﨑兼彰

鉄と鋼　100　1132-1139　2014年

Fe-Mn-C TWIP鋼における室温動的ひずみ時効の影響因子 査読有り

小山元道, 秋山英二, 津﨑兼彰

鉄と鋼　100　1123-1131　2014年

水素チャージ下引張試験におけるAl添加型TWIP鋼の水素脆化 査読有り

小山元道, 秋山英二, 津﨑兼彰

鉄と鋼　100　662-667　2014年

Tensile Testing with Cyclic Strain Holding to Analyze Dynamic Recrystallization of Pure Lead 査読有り

Muramatsu, Mayu, Koyama, Motomichi, Watanabe, Ikumu

ADVANCES IN MATERIALS SCIENCE AND ENGINEERING　2014　2014年

DOI： 10.1155/2014/498674 　

ISSN：1687-8434

eISSN：1687-8442

Effects of Static and Dynamic Strain Aging on Hydrogen Embrittlement in TWIP Steels Containing Al

Motomichi Koyama, Eiji Akiyama, Kaneaki Tsuzaki

TETSU TO HAGANE-JOURNAL OF THE IRON AND STEEL INSTITUTE OF JAPAN　100　(9)　1132-1139　2014年

DOI： 10.2355/tetsutohagane.100.1132 　

ISSN：0021-1575

eISSN：1883-2954

Factors Affecting Static Strain Aging Under Stress at Room Temperature in a Fe-Mn-C Twinning-Induced Plasticity Steel

Motomichi Koyama, Eiji Akiyama, Kaneaki Tsuzaki

TETSU TO HAGANE-JOURNAL OF THE IRON AND STEEL INSTITUTE OF JAPAN　100　(9)　1123-1131　2014年

DOI： 10.2355/tetsutohagane.100.1123 　

ISSN：0021-1575

eISSN：1883-2954

Hydrogen Embrittlement in Al-Added Twinning-Induced Plasticity Steels Evaluated by Tensile Tests during Hydrogen Charging

Motomichi Koyama, Eiji Akiyama, Kaneaki Tsuzaki

TETSU TO HAGANE-JOURNAL OF THE IRON AND STEEL INSTITUTE OF JAPAN　100　(5)　70-75　2014年

DOI： 10.2355/tetsutohagane.100.662 　

ISSN：0021-1575

eISSN：1883-2954

Microstructure characteristic and its effect on mechanical and shape memory properties in a Fe-17Mn-8Si-0.3C alloy 査読有り

Motomichi Koyama, Takahiro Sawaguchi, Kaneaki Tsuzaki

JOURNAL OF ALLOYS AND COMPOUNDS　573　15-19　2013年10月

DOI： 10.1016/j.jallcom.2013.03.289 　

ISSN：0925-8388

eISSN：1873-4669

Hydrogen-assisted quasi-cleavage fracture in a single crystalline type 316 austenitic stainless steel 査読有り

Motomichi Koyama, Eiji Akiyama, Takahiro Sawaguchi, Kazuyuki Ogawa, Irina V. Kireeva, Yury I. Chumlyakov, Kaneaki Tsuzaki

CORROSION SCIENCE　75　345-353　2013年10月

DOI： 10.1016/j.corsci.2013.06.018 　

ISSN：0010-938X

eISSN：1879-0496

Hydrogen-assisted failure in a twinning-induced plasticity steel studied under in situ hydrogen charging by electron channeling contrast imaging 査読有り

Motomichi Koyama, Eiji Akiyama, Kaneaki Tsuzaki, Dierk Raabe

ACTA MATERIALIA　61　(12)　4607-4618　2013年7月

DOI： 10.1016/j.actamat.2013.04.030 　

ISSN：1359-6454

TWIP Effect and Plastic Instability Condition in an Fe-Mn-C Austenitic Steel 査読有り

Motomichi Koyama, Takahiro Sawaguchi, Kaneaki Tsuzaki

ISIJ INTERNATIONAL　53　(2)　323-329　2013年

DOI： 10.2355/isijinternational.53.323 　

ISSN：0915-1559

eISSN：1347-5460

Grain refinement effect on cryogenic tensile ductility in a Fe-Mn-C twinning-induced plasticity steel 査読有り

Motomichi Koyama, Taekyung Lee, Chong Soo Lee, Kaneaki Tsuzaki

Materials and Design　49　234-241　2013年

DOI： 10.1016/j.matdes.2013.01.061 　

ISSN：1873-4197 0261-3069

Factors Affecting Static Strain Aging under Stress at Room Temperature in a Fe-Mn-C Twinning-induced Plasticity Steel 査読有り

Motomichi Koyama, Eiji Akiyama, Kaneaki Tsuzaki

ISIJ INTERNATIONAL　53　(6)　1089-1096　2013年

DOI： 10.2355/isijinternational.53.1089 　

ISSN：0915-1559

Effects of static and dynamic strain aging on hydrogen embrittlement in twip steels containing al 査読有り

Motomichi Koyama, Eiji Akiyama, Kaneaki Tsuzaki

ISIJ International　53　(7)　1268-1274　2013年

DOI： 10.2355/isijinternational.53.1268 　

ISSN：0915-1559

Premature Fracture Mechanism in an Fe-Mn-C Austenitic Steel 査読有り

Motomichi Koyama, Takahiro Sawaguchi, Kaneaki Tsuzaki

METALLURGICAL AND MATERIALS TRANSACTIONS A-PHYSICAL METALLURGY AND MATERIALS SCIENCE　43A　(11)　4063-4074　2012年11月

DOI： 10.1007/s11661-012-1220-7 　

ISSN：1073-5623

eISSN：1543-1940

Effect of deformation temperature on tensile properties in a pre-cooled Fe-Mn-C austenitic steel 査読有り

Motomichi Koyama, Takahiro Sawaguchi, Kaneaki Tsuzaki

MATERIALS SCIENCE AND ENGINEERING A-STRUCTURAL MATERIALS PROPERTIES MICROSTRUCTURE AND PROCESSING　556　331-336　2012年10月

DOI： 10.1016/j.msea.2012.06.095 　

ISSN：0921-5093

eISSN：1873-4936

Hydrogen-induced delayed fracture of a Fe-22Mn-0.6C steel pre-strained at different strain rates 査読有り

Motomichi Koyama, Eiji Akiyama, Kaneaki Tsuzaki

SCRIPTA MATERIALIA　66　(11)　947-950　2012年6月

DOI： 10.1016/j.scriptamat.2012.02.040 　

ISSN：1359-6462

Effect of hydrogen content on the embrittlement in a Fe-Mn-C twinning-induced plasticity steel 査読有り

Motomichi Koyama, Eiji Akiyama, Kaneaki Tsuzaki

CORROSION SCIENCE　59　277-281　2012年6月

DOI： 10.1016/j.corsci.2012.03.009 　

ISSN：0010-938X

Tensile deformation behavior of Fe-Mn-C TWIP steel with ultrafine elongated grain structure 査読有り

Taekyung Lee, Motomichi Koyama, Kaneaki Tsuzaki, You-Hwan Lee, Chong Soo Lee

MATERIALS LETTERS　75　169-171　2012年5月

DOI： 10.1016/j.matlet.2012.02.012 　

ISSN：0167-577X

Hydrogen-induced cracking at grain and twin boundaries in an Fe-Mn-C austenitic steel 査読有り

Motomichi Koyama, Eiji Akiyama, Takahiro Sawaguchi, Dierk Raabe, Kaneaki Tsuzaki

SCRIPTA MATERIALIA　66　(7)　459-462　2012年4月

DOI： 10.1016/j.scriptamat.2011.12.015 　

ISSN：1359-6462

Influence of Dislocation Separation on Dynamic Strain Aging in a Fe-Mn-C Austenitic Steel 査読有り

Motomichi Koyama, Takahiro Sawaguchi, Kaneaki Tsuzaki

MATERIALS TRANSACTIONS　53　(3)　546-552　2012年3月

DOI： 10.2320/matertrans.M2011342 　

ISSN：1345-9678

eISSN：1347-5320

Fe-Mn-C オーステナイト鋼のTWIP効果と塑性不安定条件 査読有り

小山元道, 澤口孝宏, 津﨑兼彰

鉄と鋼　98　(6)　229-236　2012年

DOI： 10.2355/tetsutohagane.98.229 　

ISSN：0021-1575

Hydrogen embrittlement in a Fe-Mn-C ternary twinning-induced plasticity steel 査読有り

Motomichi Koyama, Eiji Akiyama, Kaneaki Tsuzaki

CORROSION SCIENCE　54　1-4　2012年1月

DOI： 10.1016/j.corsci.2011.09.022 　

ISSN：0010-938X

Quasi-cleavage Fracture along Annealing Twin Boundaries in a Fe-Mn-C Austenitic Steel 査読有り

Motomichi Koyama, Takahiro Sawaguchi, Kaneaki Tsuzaki

ISIJ INTERNATIONAL　52　(1)　161-163　2012年

DOI： 10.2355/isijinternational.52.161 　

ISSN：0915-1559

Inverse grain size dependence of critical strain for serrated flow in a Fe-Mn-C twinning-induced plasticity steel 査読有り

Motomichi Koyama, Takahiro Sawaguchi, Kaneaki Tsuzaki

PHILOSOPHICAL MAGAZINE LETTERS　92　(3)　145-152　2012年

DOI： 10.1080/09500839.2011.640645 　

ISSN：0950-0839

Selective appearance of epsilon-martensitic transformation and dynamic strain aging in Fe-Mn-C austenitic steels 査読有り

Motomichi Koyama, Takahiro Sawaguchi, Kaneaki Tsuzaki

PHILOSOPHICAL MAGAZINE　92　(24)　3051-3063　2012年

DOI： 10.1080/14786435.2012.685769 　

ISSN：1478-6435

eISSN：1478-6443

Hydrogen Embrittlement in Al-added Twinning-induced Plasticity Steels Evaluated by Tensile Tests during Hydrogen Charging 査読有り

Motomichi Koyama, Eiji Akiyama, Kaneaki Tsuzaki

ISIJ INTERNATIONAL　52　(12)　2283-2287　2012年

DOI： 10.2355/isijinternational.52.2283 　

ISSN：0915-1559

eISSN：1347-5460

Work hardening and uniform elongation of an ultrafine-grained Fe-33Mn binary alloy 査読有り

M. Koyama, T. Sawaguchi, K. Tsuzaki

MATERIALS SCIENCE AND ENGINEERING A-STRUCTURAL MATERIALS PROPERTIES MICROSTRUCTURE AND PROCESSING　530　659-663　2011年12月

DOI： 10.1016/j.msea.2011.10.038 　

ISSN：0921-5093

Nanoindentation/atomic force microscopy analyses of ε-martensitic transformation and shape memory effect in Fe-28Mn-6Si-5Cr alloy. 査読有り

Scripta Materialia　65　(11)　942-945　2011年12月

DOI： 10.1016/j.scriptamat.2011.08.010 　

ISSN：1359-6462

Work hardening associated with epsilon-martensitic transformation, deformation twinning and dynamic strain aging in Fe-17Mn-0.6C and Fe-17Mn-0.8C TWIP steels 査読有り

Motomichi Koyama, Takahiro Sawaguchi, Taekyung Lee, Chong Soo Lee, Kaneaki Tsuzaki

MATERIALS SCIENCE AND ENGINEERING A-STRUCTURAL MATERIALS PROPERTIES MICROSTRUCTURE AND PROCESSING　528　(24)　7310-7316　2011年9月

DOI： 10.1016/j.msea.2011.06.011 　

ISSN：0921-5093

Si content dependence on shape memory and tensile properties in Fe-Mn-Si-C alloys 査読有り

M. Koyama, T. Sawaguchi, K. Tsuzaki

MATERIALS SCIENCE AND ENGINEERING A-STRUCTURAL MATERIALS PROPERTIES MICROSTRUCTURE AND PROCESSING　528　(6)　2882-2888　2011年3月

DOI： 10.1016/j.msea.2010.12.065 　

ISSN：0921-5093

Effect of deformation temperature on work hardening behavior in Fe-17Mn-0.6C and Fe-17Mn-0.8C steels. 査読有り

Proceedings of HMnS　2011年

Continuous Transition of Deformation Modes in Fe-30Mn-5Si-1Al Alloy 査読有り

Motomichi Koyama, Takahiro Sawaguchi, Kazuyuki Ogawa, Takehiko Kikuchi, Masato Murakami

MATERIALS TRANSACTIONS　51　(7)　1194-1199　2010年7月

DOI： 10.2320/matertrans.M2010073 　

ISSN：1345-9678

eISSN：1347-5320

The improvement of shape recovery property through training treatment in an Fe-30Mn-5Si-1Al

M. Koyama, T. Sawaguchi, K. Ogawa, T. Kikuchi, M. Murakami

Proceedings of the International Conference on Martensitic Transformations, ICOMAT-08　583-586　2009年12月1日

Fe-30Mn-5Si-1Al合金における塑性変形様式の連続遷移 査読有り

Koyama Motomichi, Sawaguchi Takahiro, Ogawa Kazuyuki, Kikuchi Takehiko, Murakami Masato

日本金属学会誌　73　(3)　174-179　2009年3月

DOI： 10.2320/jinstmet.73.174 　

ISSN：0021-4876

eISSN：1880-6880

Role of Si on the shape memory property of Fe-Mn-Si-C based alloys 査読有り

M. Koyama, T. Sawaguchi, M. Murakami, K. Tsuzaki

ESOMAT 2009 - 8TH EUROPEAN SYMPOSIUM ON MARTENSITIC TRANSFORMATIONS　02015　2009年

DOI： 10.1051/esomat/200902015 　

The effects of thermomechanical training treatment on the deformation characteristics of Fe-Mn-Si-Al alloys 査読有り

Motomichi Koyama, Takahiro Sawaguchi, Kazuyuki Ogawa, Takehiko Kikuchi, Masato Murakami

MATERIALS SCIENCE AND ENGINEERING A-STRUCTURAL MATERIALS PROPERTIES MICROSTRUCTURE AND PROCESSING　497　(1-2)　353-357　2008年12月

DOI： 10.1016/j.msea.2008.07.026 　

ISSN：0921-5093

Mechanism of reversible transformation-induced plasticity of Fe-Mn-Si shape memory alloys 査読有り

Takahiro Sawaguchi, Leandru-Gheorghe Bujoreanu, Takehiko Kikuchi, Kazuyuki Ogawa, Motomichi Koyama, Masato Murakami

SCRIPTA MATERIALIA　59　(8)　826-829　2008年10月

DOI： 10.1016/j.scriptamat.2008.06.030 　

ISSN：1359-6462

AFM observation of microstructural changes in Fe-Mn-Si-Al shape memory alloy 査読有り

Motomichi Koyama, Masato Murakami, Kazuyuki Ogawa, Takehiko Kikuchi, Takahiro Sawaguchi

MATERIALS TRANSACTIONS　49　(4)　812-816　2008年4月

DOI： 10.2320/matertrans.MRA2007321 　

ISSN：1345-9678

eISSN：1347-5320

INFLUENCE OF AL CONCENTRATION ON DEFORMATION BEHAVIOR AND FRACTURE MODE OF FE-30MN-6(SI, AL) ALLOYS 査読有り

K. Ogawa, T. Sawaguchi, T. Kikuchi, M. Koyama, M. Murakami

SMST-2007: PROCEEDINGS OF THE INTERNATIONAL CONFERENCE ON SHAPE MEMORY AND SUPERELASTIC TECHNOLOGIES　645-+　2008年

DOI： 10.1361/cp2007smst645 　

Shape memory characteristics of Fe-30Mn-5Si-lAl and Fe-28Mn-5Si-1A1-5Cr alloys 査読有り

M. Koyama, M. Murakami, K. Ogawa, T. Kikuchi, S. Sawaguchi

SMST-2007: PROCEEDINGS OF THE INTERNATIONAL CONFERENCE ON SHAPE MEMORY AND SUPERELASTIC TECHNOLOGIES　653-+　2008年

DOI： 10.1361/cp2007smst653 　

Influence of Al on shape memory effect and twinning induced plasticity of Fe-Mn-Si-Al system alloy 査読有り

Motomichi Koyama, Masato Murakami, Kazuyuki Ogawa, Takehiko Kikuchi, Takahiro Sawaguchi

MATERIALS TRANSACTIONS　48　(10)　2729-2734　2007年10月

DOI： 10.2320/matertrans.MRA2007124 　

ISSN：1345-9678

eISSN：1347-5320

Fe-30Mn-5Si-1Al 形状記憶合金の原子間力顕微鏡組織観察 査読有り

小山元道, 村上 雅人, 小川 一行, 菊池 武丕児, 澤口 孝弘

日本金属学会誌　71　(9)　672-677　2007年9月

DOI： 10.2320/jinstmet.71.672 　

ISSN：0021-4876

eISSN：1880-6880

Fe-Mn-Si-Al 系合金の形状記憶効果と双晶誘起塑性に及ぼすAl の影響 査読有り

小山 元道, 村上雅人, 小川 一行, 菊池 武丕児, 澤口 孝弘

日本金属学会誌　71　(6)　502-507　2007年6月

DOI： 10.2320/jinstmet.71.502 　

ISSN：0021-4876

eISSN：1880-6880