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2018 Fiscal Year Research-status Report

Development of a strong and ductile Ti-based bulk multi-gradients material utilizing friction stir powder surface processing technique and phase transformation theory

Research Project

Project/Area Number 18K14027
Research InstitutionOsaka University

Principal Investigator

劉 恢弘  大阪大学, 接合科学研究所, 助教 (40748943)

Project Period (FY) 2018-04-01 – 2020-03-31
KeywordsTi / Multi-gradients material / Friction stir processing / Phase transformation
Outline of Annual Research Achievements

In this study, we utilized friction stir processing to ultra-refine and alloying both-surfaces of alpha-type Ti to develop a novel bulk Ti-based multi-gradients material (MGM). Through proper heat treatments, this MGM is expected to simultaneously possess multi-gradients, thus having a great potential to be strong and ductile due to strong surfaces and ductile core, respectively. A beta-type Ti-alloy (Ti-15-3) sheet of 1.5 mm thick was lap-joined on an alpha-type Ti sheet by friction stir processing under an optimal condition with a rotation speed of 250 rpm, a travel speed of 100 mm/min and a plunge length of 1.9 mm using a WC-based-alloy tool with a shoulder diameter of 12 mm, a probe diameter of 6 mm and a probe length of 1.8 mm. The same processing was also conducted on the other surface of the alpha-type Ti sheet to fabricate a Ti-based plate with beta-phase surfaces and alpha-phase core. The transverse cross section of the fabricated plate was carefully inspected and no defect was visible throughout the cross section, suggesting that the sound weld was achieved between the alpha-Ti and beta-Ti-alloy sheets. Moreover, ultrafine- and coarse-grained microstructures were identified in the surface and core regions, respectively. These results indicated that a bulk Ti-based MGM was successfully fabricated, in which ultrafine-grained beta-phase, ultrafine-grained (beta+alpha)-phase, and coarse-grained alpha-phase microstructures were produced in the top surfaces, subsurfaces, and core of the plate, respectively.

Current Status of Research Progress
Current Status of Research Progress

2: Research has progressed on the whole more than it was originally planned.

Reason

The objective of this study is to develop a novel bulk Ti-based multi-gradients material (MGM) utilizing the friction stir processing technique and phase transformation theory. In the last year, a beta-type Ti-alloy sheet with a thickness of 1.5 mm was lap-joined on an alpha-type Ti sheet by friction stir processing at an optimal processing condition with a plunge length of 1.9 mm using a WC-based-alloy tool with a probe length of 1.8 mm. The same processing was conducted on the other side of the alpha-type Ti sheet so that a Ti-based plate with beta-phase surfaces and alpha-phase core was obtained. The results showed that a bulk Ti-based MGM with the absence of defects, contaminations and porosities was successfully fabricated, in which ultrafine-grained beta-phase, ultrafine-grained (beta+alpha)-phase, and coarse-grained alpha-phase microstructures were obtained in the top surfaces, subsurfaces, and core of the plate, respectively. However, the most appropriate heat treatment has still not been conducted on the fabricated plate to induce the desired phase transformation in order to achieve the best combination of strength and ductility in the plate as planned. Therefore, based on the above views, we consider that the study is progressing rather smoothly.

Strategy for Future Research Activity

In the last year, a novel bulk Ti-based multi-gradients material (MGM), in which ultrafine-grained beta-phase, ultrafine-grained (beta+alpha)-phase, and coarse-grained alpha-phase microstructures were obtained in the top surfaces, subsurfaces, and core of the plate, respectively, had been successfully fabricated. For the next step, the heat treatment will be conducted and optimized on the fabricated plate in order to induce the desired phase transformation in the beta phases. The microstructure of the fabricated plates with and without heat treatment will be systematically inspected by optical microscopy, X-ray diffraction, scanning electron microscopy, electron backscatter diffraction and transmission electron microscopy. Mechanical properties including hardness distribution, tensile properties and fatigue properties of the fabricated plates are planned to be evaluated. Furthermore, deformation mechanism of the optimized bulk MGM will be systematically investigated by in-situ SEM/EBSD observation during tensile deformation. The obtained findings might not only assist to develop a novel strong and ductile Ti-based bulk MGM for structural applications, but also provide an innovative strategy to develop desired gradient materials utilizing the friction stir processing principle and phase transformation theory.

  • Research Products

    (28 results)

All 2019 2018

All Journal Article (7 results) (of which Int'l Joint Research: 1 results,  Peer Reviewed: 7 results) Presentation (21 results) (of which Int'l Joint Research: 3 results,  Invited: 3 results)

  • [Journal Article] High-cycle fatigue properties of an easily hot-workable (α+β)-type titanium alloy butt joint prepared by friction stir welding below β transus temperature2019

    • Author(s)
      Masaaki Nakai, Mitsuo Niinomi, Kazuya Komine, Huihong Liu, Yoshiaki Morisada, Hidetoshi Fujii
    • Journal Title

      Materials Science and Engineering: A

      Volume: 742 Pages: 553-563

    • DOI

      10.1016/j.msea.2018.10.103

    • Peer Reviewed
  • [Journal Article] Elucidation of interface joining mechanism during friction stir welding through Cu/Cu-10Zn interfacial observations2019

    • Author(s)
      Huihong Liu, Kohsaku Ushioda, Hidetoshi Fujii
    • Journal Title

      Acta Materialia

      Volume: 166 Pages: 324-334

    • DOI

      10.1016/j.actamat.2019.01.004

    • Peer Reviewed
  • [Journal Article] Probing tool durability in stationary shoulder friction stir welding2019

    • Author(s)
      B. Vicharapu, H.H. Liu, H. Fujii, N. Ma, A. De
    • Journal Title

      The Proceedings of Friction Stir Welding and Processing X 2019 TMS Annual Meeting & Exhibition

      Volume: - Pages: 91-98

    • DOI

      10.1007/978-3-030-05752-7_9

    • Peer Reviewed / Int'l Joint Research
  • [Journal Article] Dissimilar friction stir welding of pure Ti and pure Al2018

    • Author(s)
      Jeong-Won Choi, Huihong Liu, Hidetoshi Fujii
    • Journal Title

      Materials Science and Engineering: A

      Volume: 730 Pages: 168-176

    • DOI

      10.1016/j.msea.2018.05.117

    • Peer Reviewed
  • [Journal Article] Elucidation of microstructural evolution of beta-type titanium alloy joint during friction stir welding using liquid CO2 cooling2018

    • Author(s)
      Huihong Liu, Kohsaku Ushioda, Hidetoshi Fujii
    • Journal Title

      Materials Characterization

      Volume: 145 Pages: 490-500

    • DOI

      10.1016/j.matchar.2018.09.005

    • Peer Reviewed
  • [Journal Article] Clarification of interface joining mechanism of friction stir welding by Cu/Cu-10Zn interfacial observation2018

    • Author(s)
      Huihong Liu, Kohsaku Ushioda, Hidetoshi Fujii
    • Journal Title

      Proceedings of the 12th International Symposium on Friction Stir Welding

      Volume: 12 Pages: 7B-1-1-7B-1-5

    • Peer Reviewed
  • [Journal Article] Dissimilar friction stir welding of pure Ti and pure Mg using an Al filler material2018

    • Author(s)
      Jeong-Won Choi, Huihong Liu, Kohsaku Ushioda, Hidetoshi Fujii
    • Journal Title

      Proceedings of the 12th International Symposium on Friction Stir Welding

      Volume: 12 Pages: P4-1-P4-5

    • Peer Reviewed
  • [Presentation] Microstructure and mechanical properties of dissimilar Ti/Mg joint fabricated by friction stir welding2019

    • Author(s)
      Jeong-Won Choi, Huihong Liu, Kohsaku Ushioda, Hidetoshi Fujii
    • Organizer
      TMS2019 148th Annual Meeting & Exhibition
  • [Presentation] Interface Joining Mechanism of Friction Stir Welding Investigated by Cu/Cu10Zn Interfacial Observation2019

    • Author(s)
      H.H. Liu, K. Ushioda, H. Fujii
    • Organizer
      4th Osaka University-JWRI/NTU-MSE Workshop
    • Int'l Joint Research / Invited
  • [Presentation] Ti-6Al-4V合金/SUS316L鋼における極低回転摩擦圧接2019

    • Author(s)
      劉恢弘, 藤井英俊
    • Organizer
      日本金属学会 2019年春期講演大会
  • [Presentation] Cu/Cu-10Znの界面観察によるCuの摩擦攪拌接合における界面接合機構の解明2018

    • Author(s)
      劉 恢弘, 藤井 英俊
    • Organizer
      溶接学会 平成30年度春季全国大会
  • [Presentation] 純Al薄膜をフィラー材料として用いた純Tiと純Mgの異材摩擦攪拌接合2018

    • Author(s)
      崔 正原, 劉 恢弘, 潮田 浩作, 藤井 英俊
    • Organizer
      溶接学会 平成30年度春季全国大会
  • [Presentation] 炭素鋼の大荷重局部変形接合2018

    • Author(s)
      宮垣 徹也, 劉 恢弘, 釜井 正善, 藤井 英俊
    • Organizer
      溶接学会 平成30年度春季全国大会
  • [Presentation] X線イメージングを利用したAl-Cu合金のTIG溶接時に発生する凝固割れのその場観察2018

    • Author(s)
      山下 大輔, 柳楽 知也, 釜井 正善, 青木 祥宏, 劉 恢弘, 藤井 英俊
    • Organizer
      溶接学会 平成30年度春季全国大会
  • [Presentation] Friction stir welding of dissimilar pure Ti/pure Mg using an Al filler material2018

    • Author(s)
      Jeong-Won Choi,Huihong Liu, Kohsaku Ushioda, Hidetoshi Fujii
    • Organizer
      軽金属溶接協会 2018年度年次講演大会
  • [Presentation] 高輝度X線を利用したその場観察によるAl-Cu合金のTIG溶接で生じる凝固割れの形成機構の解明2018

    • Author(s)
      山下 大輔, 柳楽 知也, 釜井 正善, 青木 祥宏, 劉 恢弘, 藤井 英俊
    • Organizer
      軽金属溶接協会 2018年度年次講演大会
  • [Presentation] Eludication of Interface Joining Mechanism of Friction Stir Welding through Cu/Cu-10Zn Interface Observation2018

    • Author(s)
      H.H. Liu, K. Ushioda, H. Fujii
    • Organizer
      Japan-China Joining and Welding Workshop 2018 (JCJW2018)-Cutting Edge of Additive Manufacturing, Laser Processing and Friction Stirring Welding
    • Int'l Joint Research / Invited
  • [Presentation] 大荷重局部変形による炭素鋼の低温接合2018

    • Author(s)
      宮垣 徹也, 劉 恢弘, 釜井 正善, 藤井 英俊
    • Organizer
      溶接学会 平成30年度秋季全国大会
  • [Presentation] 純TiとCFRPの異材摩擦攪拌接合2018

    • Author(s)
      崔 正原, 劉 恢弘, 潮田 浩作, 藤井 英俊, 永塚 公彬, 中田 一博
    • Organizer
      溶接学会 平成30年度秋季全国大会
  • [Presentation] Effect of Plate thickness on tool durability index in FSW of aluminum alloy2018

    • Author(s)
      B.Vicharapu, H.Liu, H.Fujii, N.Ma, A.De
    • Organizer
      溶接学会 平成30年度秋季全国大会
  • [Presentation] ステンレス鋼のTIG溶接時の凝固割れ2018

    • Author(s)
      山下 大輔, 柳楽 知也, 釜井 正善, 青木 祥宏, 劉 恢弘, 藤井 英俊
    • Organizer
      溶接学会 平成30年度秋季全国大会
  • [Presentation] Ti-6Al-4V合金/SUS316L鋼の異材摩擦圧接2018

    • Author(s)
      劉 恢弘, 青木 洋, 青木 祥宏, 藤井 英俊
    • Organizer
      溶接学会 平成30年度秋季全国大会
  • [Presentation] A1点以下での接合を実現する局部変形を活用した新規接合法の開発2018

    • Author(s)
      宮垣 徹也, 劉 恢弘, 釜井 正善, 藤井 英俊
    • Organizer
      日本鉄鋼協会 第176回秋期講演大会
  • [Presentation] TIG溶接時におけるステンレス鋼の凝固割れのその場観察2018

    • Author(s)
      山下 大輔, 柳楽 知也, 釜井 正善, 青木 祥宏, 劉 恢弘, 藤井 英俊
    • Organizer
      日本鉄鋼協会 第176回秋期講演大会
  • [Presentation] チタン合金/ステンレス鋼における異材摩擦圧接2018

    • Author(s)
      劉 恢弘, 青木 洋, 青木 祥宏, 藤井 英俊
    • Organizer
      日本金属学会 2018年秋期講演大会
  • [Presentation] Microstructure and mechanical properties of a beta-type titanium alloy joint fabricated by friction stir welding2018

    • Author(s)
      H.Liu, H. Fujii
    • Organizer
      The 3rd International Symposium on Creation of Life Innovation Materials for Interdisciplinary and International Researcher Development (iLIM-3)
    • Int'l Joint Research / Invited
  • [Presentation] In-situ observation of solidification cracking during TIG welding by X-ray imaging2018

    • Author(s)
      D. Yamashita, T. Nagira, M. Kamai, Y. Aoki, H. Liu, H. Fujii
    • Organizer
      4th international conference on welding and failure analysis of engineering materials
  • [Presentation] Low-temperature joining of carbon steel by large load and localized deformation2018

    • Author(s)
      T. Miyagaki, H. Liu, M. Kamai, H. Fujii
    • Organizer
      4th international conference on welding and failure analysis of engineering materials

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Published: 2019-12-27  

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