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Motomichi Koyama Last modified date:2017.05.08

Assistant Professor / Faculty of Engineering
Department of Mechanical Engineering
Faculty of Engineering




E-Mail
Academic Degree
Ph.D, Eng.
Field of Specialization
Materials science and engineering
Outline Activities
My research topic is to reveal mechanisms of work hardening, embrittlement, and fatigue phenomena in advanced high strength steels.
Excellent mechanical properties can be designed through enhancement of work hardening and suppression of embrittlement and fatigue failure. We are attempting to propose a new material design strategy by clarifying the mechanisms of work hardening, embrittlement, and fatigue.
Our main tools are mechanical testing machines and microscopes such as SEM with EBSD and ECCI. Our future goal is placed on proposing the mechanisms based on metallography and mechanics.
Research
Research Interests
  • Enhancing fatigue crack resistance through microstructural laminates
    keyword : laminated structrue, fatigue crack
    2015.04~2018.03.
  • Understanding I-S interaction-related dynamic strain aging: toward its application
    keyword : I-S interaction, dynamic strain aging
    2014.04~2018.03.
  • Analysis on damage evolution of dual phase steel
    keyword : dual phase steel, damage evolution
    2014.04~2018.03.
  • Clarifying mechanisms of hydrogen embrittlement of austenitic steels, specifically high Mn steels
    keyword : hydrogen embrittlement, austenite
    2013.12~2015.03.
Academic Activities
Papers
1. Motomichi Koyama, Zhao Zhang, Meimei Wang, Dirk Ponge, Dierk Raabe, Kaneaki Tsuzaki, Hiroshi Noguchi, Cemal Cem Tasan, Bone-like crack resistance in hierarchical metastable nano-laminate steels, Science, 355, 2017.03.
2. Yun-Byum Ju, Motomichi Koyama, Takahiro Sawaguchi, Kaneaki Tsuzaki, 野口 博司, In situ microscopic observations of low-cycle fatigue-crack propagation in high-Mn austenitic alloys with deformation-induced ε-martensitic transformation, Acta Materialia, 112, 2016.04.
3. Motomichi Koyama, Shota Okazaki, Takahiro Sawaguchi, Kaneaki Tsuzaki, Hydrogen Embrittlement Susceptibility of Fe-Mn Binary Alloys with High Mn Content: Effects of Stable and Metastable e-Martensite, and Mn Concentration, METALLURGICAL AND MATERIALS TRANSACTIONS A, 47A, 2016.06.
4. Motomichi Koyama, Cemal Cem Tasan, Eiji Akiyama, Kaneaki Tsuzaki, Dierk Raabe, Hydrogen-assisted decohesion and localized plasticity in dual phase steel , Acta Materialia, 70, 2014.02.
5. Motomichi Koyama, Hauke Springer, Sergiy V. Merzlikin, Kaneaki Tsuzaki, Eiji Akiyama, Dierk Raabe, Hydrogen embrittlement associated with strain localization in a precipitation-hardened Fe-Mn-Al-C light weight austenitic steel, International Journal of Hydrogen Energy, 39, 2014.01.
6. Motomichi Koyama, Eiji Akiyama, Takahiro Sawaguchi, Kazuyuki Ogawa, Irina V. Kireeva, Yuriy I. Chumlyakov, Kaneaki Tsuzaki, Hydrogen-assisted quasi-cleavage fracture in a single crystalline type 316 austenitic stainless steel, Corrosion Science , 75, 2013.10.
7. Motomichi Koyama, Eiji Akiyama, Kaneaki Tsuzaki, Effects of static and dynamic strain aging on hydrogen embrittlement in twip steels containing Al, ISIJ International , 53, 7, 2013.07.
8. Motomichi Koyama, Eiji Akiyama, Kaneaki Tsuzaki, Factors affecting static strain aging under stress at room temperature in a Fe-Mn-C twinning-induced plasticity steel, ISIJ International , 53, 6, 2013.06.
9. Motomichi Koyama, Eiji Akiyama, Kaneaki Tsuzaki, Dierk Raabe, Hydrogen-assisted failure in a twinning-induced plasticity steel studied under in situ hydrogen charging by electron channeling contrast imaging, Acta Materialia , 61, 12, 2013.07.
10. Motomichi Koyama, Takahiro Sawaguchi, Kaneaki Tsuzaki, TWIP Effect and plastic instability condition in an Fe-Mn-C austenitic steel, ISIJ International , 53, 2, 2012.02.
11. Motomichi Koyama, Eiji Akiyama, Kaneaki Tsuzaki, Hydrogen embrittlement in Al-added twinning-induced plasticity steels evaluated by tensile tests during hydrogen charging, ISIJ International , 52, 12, 2012.12.
12. Motomichi Koyama, Takahiro Sawaguchi, Kaneaki Tsuzaki, Premature fracture mechanism in an Fe-Mn-C austenitic steel, Metallurgical and Materials Transactions A: Physical Metallurgy and Materials Science , 43, 11, 2012.11.
13. Motomichi Koyama, Takahiro Sawaguchi, Kaneaki Tsuzaki, Effect of deformation temperature on tensile properties in a pre-cooled Fe-Mn-C austenitic steel, Materials Science and Engineering A , 556, 2012.10.
14. Motomichi Koyama, Takahiro Sawaguchi, Kaneaki Tsuzaki, Selective appearance of epsilon-martensitic transformation and dynamic strain aging in Fe-Mn-C austenitic steels, Philosophical Magazine , 92, 24, 2012.08.
15. Motomichi Koyama, Eiji Akiyama, Kaneaki Tsuzaki, Hydrogen-induced delayed fracture of a Fe-22Mn-0.6C steel pre-strained at different strain rates, Scripta Materialia , 66, 11, 2012.06.
16. Motomichi Koyama, Eiji Akiyama, Kaneaki Tsuzaki, Effect of hydrogen content on the embrittlement in a Fe-Mn-C twinning-induced plasticity steel, Corrosion Science , 59, 2012.06.
17. Motomichi Koyama, Takahiro Sawaguchi, Kaneaki Tsuzaki, Influence of dislocation separation on dynamic strain aging in a Fe-Mn-C austenitic steel, Materials Transactions , 53, 3, 2012.03.
18. Motomichi Koyama, Eiji Akiyama, Takahiro Sawaguchi, Dierk Raabe, Kaneaki Tsuzaki, Hydrogen-induced cracking at grain and twin boundaries in an Fe-Mn-C austenitic steel, Scripta Materialia , 66, 7, 2012.04.
19. Motomichi Koyama, Takahiro Sawaguchi, Kaneaki Tsuzaki, Inverse grain size dependence of critical strain for serrated flow in a Fe-Mn-C twinning-induced plasticity steel, Philosophical Magazine Letters , 92, 3, 2012.03.
20. Motomichi Koyama, Takahiro Sawaguchi, Kaneaki Tsuzaki, Quasi-cleavage fracture along annealing twin boundaries in a Fe-Mn-C austenitic steel, ISIJ International , 52, 1, 2011.01.
21. Motomichi Koyama, Eiji Akiyama, Kaneaki Tsuzaki, Hydrogen embrittlement in a Fe-Mn-C ternary twinning-induced plasticity steel , Corrosion Science , 54, 1, 2012.01.
22. Motomichi Koyama, Takahiro Sawaguchi, Kaneaki Tsuzaki, Work hardening and uniform elongation of an ultrafine-grained Fe-33Mn binary alloy, Materials Science and Engineering A , 530, 1, 2011.12.
23. Motomichi Koyama, Takahiro Sawaguchi, Teakyung Lee, Chong Soo Lee, Kaneaki Tsuzaki, 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, Materials Science and Engineering A , 528, 24, 2011.09.
24. Motomichi Koyama, Takahiro Sawaguchi, Kaneaki Tsuzaki, Si content dependence on shape memory and tensile properties in Fe-Mn-Si-C alloys , Materials Science and Engineering A , 528, 6, 2011.03.
Membership in Academic Society
  • The Japan Institute of Metals and Materials
  • The Iron and Steel Institute of Japan
  • The Japan Society of Mechanical Engineering