| Project/Area Number |
14205103
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| Research Category |
Grant-in-Aid for Scientific Research (A)
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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, Department of Production Systems Engineering, Professor, 工学部, 教授 (90111921)
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| Co-Investigator(Kenkyū-buntansha) |
TODAKA Yoshikazu Toyohashi University of Technology, Manufacturing Technology Center, Research Associate, 工作センター, 助手 (50345956)
TUCHIYA Koichi Toyohashi University of Technology, Department of Production Systems Engineering, Associate Professor, 工学部, 助教授 (50236907)
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| Project Period (FY) |
2002 – 2003
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| Keywords | Nanocrystalline / Severe plastic deformation / Shot peening / Drilling / Steel / Cementite |
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| Research Abstract |
Nanocrystalline materials have attracted considerable scientific interests in the past decade. Particle impact deformation, shot peening, wear and drilling processing were demonstrated to produce nanocrystalline structure. Nanocrystalline layers with several μm thick at surface and interior of specimens were successfully produced by these processes. The nanograined structure in steels formed by these processes was randomly oriented equiaxed nanograins with about 20 nm: in diameter. The nanocrystalline layer has the homogeneous nanostructure with sharp boundary between work-hardened region: The intermediate state between the nanocrystalline and work-hardened states was not observed. The morphologies, such as spheroidal and lamellar cementites, disappeared by nanocrystallization. The hardness of the nanocrystalline layer is extremely higher (8〜14 GPa) than that of work-hardened region. The annealing of nanocrystalline layer shows substantially, slow grain growth. This annealing behavior is quite different from the work-hardened region which is characterized by recrystallization and fast grain growth. These characteristics are similar to those observed in the nanocrystalline. structures produced by ball milling and ball drop deformation processing The necessary condition to produce nanocrystalline materiall by deformation may be a large strain of more than about 7 in true strain. Nanograined structure in steels f is probably formed by the deformation induced amorphization and following mechanically induced nanocrystallization.
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