2007 Fiscal Year Final Research Report Summary
The quantitative evaluation of effect of strain gradient on the strengthening and structure refinement of metals during ultra large straining
| Project/Area Number |
18360329
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| Research Category |
Grant-in-Aid for Scientific Research (B)
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| Allocation Type | Single-year Grants |
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| Section | 一般 |
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| Research Field |
Structural/Functional materials
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| Research Institution | Toyohashi University of Technology |
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Principal Investigator |
UMEMOTO Minoru Toyohashi University of Technology, Dept.of Production Systems Engineering, Prof (90111921)
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| Co-Investigator(Kenkyū-buntansha) |
TSUCHIYA Koichi National Institute for Materials Science, Structural Functions Research Group, Researcher (50236907)
TODAKA Yoshikazu Toyohashi University of Technology, Dept.of Production Systems Engineering, Asst. Prof (50345956)
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| Project Period (FY) |
2006 – 2007
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| Keywords | ultra large strain / strain gradient / strengthening / grain refinement / high pressure torsion / crystallization / pressure induced transformation / GN dislocation |
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| Research Abstract |
In the present investigation, using specimens with different strain and strain gradient prepared by high pressure torsion machine, the effect of strain gradient on the strengthening and refinement of microstructure were studied. The measurement of hardness for HPTed pure metals such as Al, Ti, Ni, Cu, Fe revealed that recrystallization takes place in the pure metals with low melting point such as Al and Cu. Pressure induced transformation was observed in pure Ti. Thus using pure Fe in which only the effect of strain and strain gradient appears, the effect of strain and strain gradient on the hardness was studied. The clear strain gradient hardening was observed in the HPTed pure Fe. The HPTed Fe showed the ultimate tensile strength of 2GPa, and the total elongation increased with applied strain. The effect of high pressure during HPT was examined using pure Ti which transformed from phase to w phase when HPTed at high pressure. The volume fraction of CO phase increases with strain and with decreasing oxygen content. The co phase is metastable at ambient conditions and it transforms back to a phase during heating.
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[Journal Article] Dissolution of cementite in carbon steels by ball drop deformation and laser heating2007
Author(s)
Yoshikazu, Todaka, Minoru, Umemoto, Akifumi, Ohno, Mayumi, Suzuki, Yuji, Kawabata, Koichi, Tsuchiya
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Journal Title
Journal of Alloys and Compounds 434-435
Pages: 497-500
Description
「研究成果報告書概要(欧文)」より
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[Journal Article] Role of strain gradient on grain refinement by severe plastic deformation2007
Author(s)
Yoshikazu, Todaka, Minoru, Umemoto, Jun, Yin, Zhiguang, Liu, Koichi, Tsuchiya
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Journal Title
Materials Science and Engineering 462,1-2,25
Pages: 264-268
Description
「研究成果報告書概要(欧文)」より
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