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2016 Fiscal Year Annual Research Report

Study on the microstructure and high-cycle fatigue property of ultrafine grained copper processed by severe plastic deformation

Research Project

Project/Area Number 26420021
Research InstitutionOita University

Principal Investigator

後藤 真宏  大分大学, 工学部, 教授 (30170468)

Project Period (FY) 2014-04-01 – 2017-03-31
Keywords疲労 / 強変形加工 / 微細結晶粒 / 銅 / き裂 / 応力拡大係数
Outline of Annual Research Achievements

本研究では、高サイクル疲労強度特性の向上を目指し強変形加工材の微視組織構造とき裂に関わる損傷の物理的背景、き裂進展に及ぼす組織の影響と力学的背景を明らかにするため、① 「き裂の挙動と微視組織構造の関連」、②「高サイクル領域の耐疲労特性の改善」、③「実用銅合金材料の疲労強度に及ぼす組織の影響」について検討した。
①については,高応力下のき裂は、ECAP最終せん断面と関係した最大せん断応力方向に形成したせん断帯を起点に発生し、最終せん断面に平行に進展すると共に特異なき裂面形状を呈することを明らかにした。さらに、これらの原因がき裂先端の面内せん断変形に起因することを応力拡大係数を計算して力学的に明らかにした。一方、低応力下では、結晶粒の粗大化により通常寸法の結晶の材料と同様にすべり帯からき裂が発生し主応力方向に垂直に進展する。
②については、組織の非平衡度を下げることにより耐久限度の向上を試みた。具体的には低温焼なましおよび累積ひずみ量の変化が耐久限度に及ぼす影響を調べ、耐久限度の10%程度の向上を得た。
③については、コネクターなどの電子材料として広く使用され,現在も盛んに開発が行われているCu-Ni-Si系合金の疲労強度と組織構造の関係に関係して、疲労き裂の起点が結晶粒界であり、その後隣接する粒内のすべり方向に沿って進展することを明らかにした。また、時効条件により発生する不連続析出相が疲労強度に及ぼす影響を検討し、機械的性質に悪影響を及ぼす不連続析出相が疲労強度に無害であることを示すと共にその物理的背景を明らかにした。なお、不連続析出相については、強変形加工を行い組織を制御することにより、通常組織の強変形加工に比べ引張強さが30%向上することを明らかにした。

  • Research Products

    (13 results)

All 2016 Other

All Int'l Joint Research (1 results) Journal Article (7 results) (of which Int'l Joint Research: 7 results,  Peer Reviewed: 7 results,  Acknowledgement Compliant: 3 results,  Open Access: 1 results) Presentation (5 results) (of which Int'l Joint Research: 5 results)

  • [Int'l Joint Research] Korea Institute of Materials Science/Gyeongsang National University/Changwon National University(韓国)

    • Country Name
      KOREA (REP. OF KOREA)
    • Counterpart Institution
      Korea Institute of Materials Science/Gyeongsang National University/Changwon National University
  • [Journal Article] Formation mechanism of inclined fatigue-cracks in ultrafine-grained Cu processed by equal channel angular pressing2016

    • Author(s)
      Masahiro Goto, Seung Zeon Han, Takaei Yamamoto, Jyunichi Kitamura, Jee-Hyuk Ahn, Terutoshi Yakushiji, Sangshik Kim, Jehyun Lee
    • Journal Title

      International Journal of Fatigue

      Volume: 92 Pages: 577/587

    • DOI

      dx.doi.org/10.1016/j.ijfatigue.2016.02.006

    • Peer Reviewed / Int'l Joint Research / Acknowledgement Compliant
  • [Journal Article] Increasing toughness by promoting discontinuous precipitation in Cu-Ni-Si alloys2016

    • Author(s)
      Jehyun Lee, Seungzeon Han, Masahiro Goto, Sung Hwan Lim, Jee-Hyuk Ahn, Snagshik Kim, Kwho Kim
    • Journal Title

      Philosophical Magazine Letters

      Volume: 96 Pages: 196/203

    • DOI

      10.1080/09500839.2016.1189099

    • Peer Reviewed / Int'l Joint Research
  • [Journal Article] Increasing strength and conductivity of Cu alloy through abnormal plastic deformation of an intermetallic compound2016

    • Author(s)
      Seung Zeon Han, Sung Hwan Lim, Sangshik Kim, Jehyun Lee, Masahiro Goto, Hyung Giun Kim, Byungchan Han, Kwang Ho Kim
    • Journal Title

      Scientific Reports

      Volume: 6 Pages: 30907

    • DOI

      10.1038/srep30907

    • Peer Reviewed / Open Access / Int'l Joint Research
  • [Journal Article] Role of microstructure on initiation and propagation of fatigue cracks in precipitate strengthened Cu-Ni-Si alloy2016

    • Author(s)
      Masahiro Goto, Sueng Zeon Han, Sung Hwan Lim, Junichi Kitamura, Tetsuya Fujimura, Jee-hyuk Ahn, Takaei Yamamoto, Sangshik Kim, Jehyun Lee
    • Journal Title

      International Journal of Fatigue

      Volume: 87 Pages: 15/21

    • DOI

      org/10.1016/j.ijfatigue.2016.01.004

    • Peer Reviewed / Int'l Joint Research / Acknowledgement Compliant
  • [Journal Article] Relationship between Grain Growth and Formation of Fracture Surface of Ultrafine Grained Cu in High-Cycle Fatigue2016

    • Author(s)
      Masahiro Goto, Seung Zeon Han, Takaei Yamamoto, Jyunichi Kitamura, K.usno Kamil, Tetsuya Fujimura, Terutoshi Yakushiji
    • Journal Title

      Key Engineering Materials

      Volume: 713 Pages: 147/150

    • DOI

      10.4028/www.scientific.net/KEM.713.147

    • Peer Reviewed / Int'l Joint Research / Acknowledgement Compliant
  • [Journal Article] Effect of heterogeneous precipitates on fatigue behavior of age-hardened Cu-Ni-Si alloy2016

    • Author(s)
      Tetsuya Fujimura, Masahiro Goto, Seung Zeon Han, Takaei Yamamoto, Jee-Hyuk Ahn, Jyunichi Kitamura, Daigo Okuzume
    • Journal Title

      International Journal of Fracture, Fatigue and Wear

      Volume: 4 Pages: 33/38

    • Peer Reviewed / Int'l Joint Research
  • [Journal Article] Effect of superplastic forming exposure on fatigue crack propagation behavior of Ti6Al4V alloy2016

    • Author(s)
      Daeho Jeong, Yongnam Kwon, Masahiro Goto, Sangshik Kim
    • Journal Title

      Metals and Materials International

      Volume: 22 Pages: 747/754

    • DOI

      10.1007/s12540-016-6075-9

    • Peer Reviewed / Int'l Joint Research
  • [Presentation] 強変形加工した銅の組織と機械的性質2016

    • Author(s)
      藤村哲也,北村純一,Seungzeon Han,山本隆栄,後藤真宏
    • Organizer
      日本材料学会九州支部第3回学術講演会
    • Place of Presentation
      北九州国際会議場、北九州市
    • Year and Date
      2016-12-10
    • Int'l Joint Research
  • [Presentation] Relationship between Grain Growth and Formation of Fracture Surface of Ultrafine Grained Cu in High-Cycle Fatigue2016

    • Author(s)
      Masahiro Goto, Seung Zeon Han, Takaei Yamamoto, Jyunichi Kitamura, K.usno Kamil, Tetsuya Fujimura, Terutoshi Yakushiji
    • Organizer
      15th International Conference on Fracture and Damage Mechanics
    • Place of Presentation
      Hotel Melia Alicante, Alicante, Spain
    • Year and Date
      2016-09-14 – 2016-09-16
    • Int'l Joint Research
  • [Presentation] Bending fatigue strength of annealed 0.45% carbon steel specimens finished by cutting and rubbing technique utilizing cemented carbon tip2016

    • Author(s)
      Terutoshi Yakushiji, Fuminori Nakagawa, Masahiro Goto
    • Organizer
      5th International Conference on Fracture, Fatigue and Wear
    • Place of Presentation
      Kitakyushu International Congress Center, Kitakyushu
    • Year and Date
      2016-08-24 – 2016-08-26
    • Int'l Joint Research
  • [Presentation] Effects of heterogeneous precipitates on fatigue behavior of age-hardened Cu-Ni-Si alloy2016

    • Author(s)
      Tetsuya Fujimura, Masahiro Goto, Seungzeon Han, Takaei Yamamoto, Jee-Hyuk Ahn, Jyunichi Kitamura, Daigo Okuzume
    • Organizer
      5th International Conference on Fracture, Fatigue and Wear
    • Place of Presentation
      Kitakyushu International Congress Center, Kitakyushu
    • Year and Date
      2016-08-24 – 2016-08-26
    • Int'l Joint Research
  • [Presentation] Role of microstructure on mechanical properties of ultrafine grained Cu processed by different ECAP pass-numbers2016

    • Author(s)
      Masahiro Goto, Seung-zeon Han, Junichi Kitamura, Takaei Yamamoto, Terutoshi Yakushiji, Jee-hyuk Ahn, Testuya Fujimura
    • Organizer
      International Conference on Processing & Manufacturing of Advanced Materials 2016
    • Place of Presentation
      Graz Convention Center, MESSE GRAZ, Graz, Austria
    • Year and Date
      2016-05-29 – 2016-06-03
    • Int'l Joint Research

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Published: 2018-01-16   Modified: 2022-02-16  

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