Oshikawa Wataru

写真a

Title

Professor

Researcher Number(JSPS Kakenhi)

80224228
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Current Affiliation Organization 【 display / non-display 】

  • Duty   University of the Ryukyus   Faculty of Engineering   School of Engineering_Energy and Environment Program   Professor  

  • Concurrently   University of the Ryukyus   Graduate School of Engineering and Science   Material,Structural and Energy Engineering   Professor  

  • Concurrently   University of the Ryukyus   Graduate School of Engineering and Science   Solid Mechanics and Materials Engineering   Professor  

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Academic degree 【 display / non-display 】

  • The University of Tokyo -  Doctor of Engineering

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External Career 【 display / non-display 】

  • 2005.07
    　
    　

     

  • 2005.07
    　
    　

    - , University of the Ryukyus, Faculty of Engineering, Department of Mechanical Systems Engineering, Engineering Materials,Design and Processing, Associate Professor  

  • 2005.07
    　
    　

    University of the Ryukyus, Faculty of Engineering, Energy and Environment Program, Professor  

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Research Areas 【 display / non-display 】

  • Nanotechnology/Materials / Material processing and microstructure control

  • Nanotechnology/Materials / Material processing and microstructure control

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Published Papers 【 display / non-display 】

  • Study on Initial Corrosion Behavior of Arc‑thermally Spray Zn, Zn–Al, and Al–Mg Coatings Exposed in Atmospheric Environment for One‑Year

    Atsuhi Nakano, Yuki Toyota, Chihiro Morita, Kentaro Yasui, Wataru Oshikawa, Noboru Yonezawa

    International Journal of Steel Structures     2024.09 [ Peer Review Accepted ]

    Type of publication: Research paper (scientific journal)

  • Effect of Diffusion Rate of Oxygen on Soil Corrosion and Evaluation of that in Soil

      73 ( 8 ) 200 - 209   2024.08 [ Peer Review Accepted ]

    Type of publication: Research paper (scientific journal)

  • Effect of Soil Particle Diameter on Soil Corrosion

    Fujihashi Kenta, Nakagami Ryosuke, Oshikawa Wataru

    Zairyo-to-Kankyo ( Japan Society of Corrosion Engineering )  72 ( 1 ) 22 - 30   2023.01

    Type of publication: Research paper (scientific journal)

    　View Summary

    <p>The main foundation structure of photovoltaic power generation facilities is a steel pile foundation. Soil corrosion rate is regarded as 0.02 mm/year regardless of the soil. However, it is considered that corrosion rates of each soil are difference. In this study, we estimated the soil corrosion environment by measuring the physical properties of soil and evaluated the charge transfer resistance of each soil environment by AC impedance method that regarded soil as electrolyte, in order to investigate the effect of soil particle size on soil corrosion.</p><p>Glass beads of uniform sphere haven't been packed close-packed structure, and porosity of soil with particle size distribution was nearly equal to regardless of particle size. But in case of the soil that included particles less than 50μm in a large quantity, porosity of the soil was increase. Porosity of soil that had similar particle size distribution was nearly equal regardless of water content. Therefore, it is suggested that the change of soil water content was replacement liquid phase and gas phase. The charge transfer resistance of soil corrosion decreased with decrease of gas phase ratio in soil. Therefore, it is suggested that the charge transfer resistance of soil corrosion might be estimated from the soil particle size distribution and water content.</p>

  • Cracking Process in Delayed Fracture of High-Strength Steel after Long Atmospheric Exposure

    Homma T.

    ＩＳＩＪ　Ｉｎｔｅｒｎａｔｉｏｎａｌ ( 一般社団法人 日本鉄鋼協会 )  62 ( 4 ) 776 - 787   2022.04

    Type of publication: Research paper (scientific journal)

    　View Summary

    <p>This paper is the first microscopic observation of the entire cracking process in delayed fracture of high-strength steel bolt after long-term atmospheric exposure. A sufficiently fresh fracture surface exhibits the initiation of the propagating crack in a thin zone beneath the screw groove, resulting from the merging of multiple cracks nucleated therein. The fracture morphology is initially intergranular, exhibiting the three-dimensional shape of prior austenite grains, but the stress and strain states at the nucleation sites are not uniquely specified. The fracture morphology alters as the crack extends from intergranular to quasi-cleavage and fine dimples, associated with increasing stress intensity under a constant-displacement condition. The change from inter- to trans-granular fracture is continuous, implying affinity among different morphologies associated with the increased density and the distribution of potential crack nucleation sites in the crack front. The crack propagation in the quasi-cleavage and fine dimple regions is step-wise of about 50 <i>µ</i>m per step. Recent studies about the function of hydrogen in embrittlement are referred to in respect of the accumulation of strain-induced damage. The enhanced generation of strain-induced vacancies is the presumable function of hydrogen compatible with the present findings.</p>

  • Universities and Academic Associations in COVID-19

    Oshikawa Wataru

    Zairyo-to-Kankyo ( Japan Society of Corrosion Engineering )  71 ( 3 ) 61 - 62   2022.03

    Type of publication: Research paper (scientific journal)

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