2000 Fiscal Year Final Research Report Summary
Control of Interphase Bowdlerizes in Steel
| Project/Area Number |
10305050
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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 | KYOTO UNIVERSITY |
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Principal Investigator |
MAKI Tadashi kyoto Univ.Dept.of Mater.Sci & Eng. Prof., 工学研究科, 教授 (10026247)
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| Co-Investigator(Kenkyū-buntansha) |
MORITO Shigekazu Kyoto Univ, Res.Assoc., 工学研究科, 助手 (00301242)
FURUHARA Tadashi Kyoto Univ, Assoc.Prof., 工学研究科, 助教授 (50221560)
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| Project Period (FY) |
1998 – 2000
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| Keywords | Steel / Phase Transformation / Precipitation / Recryotellization / In clusion / Crystallography / Interphase Bombay |
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| Research Abstract |
The (α+γ) and (α+θ) lamellar structures are heavily cold rolled and annealed to form the microduplex structures of which α grain size is less than 1 μm. α phase exhibits a subgrain structure in the (α+γ) case whereas α phase contains both of high angle and low angle boundaries in the (α+θ) case.
VC in y.and s-Cu in α are both coherent to their matrices after solution treatment and aging. However, they become incoherent by losing the original orientation relationship after the recrystallization of matrix. After losing coherency, these precipitates coarsens vary rapidly.
In the bcc precipitation from fcc matrix in a Ni-Cr alloy, regardless of the presence of near rational orientation relationship, precipitate (bcc)/matrix(fcc) interphase boundaries exhibit planar facets that often contain ledges and regularly aligned line defects. The boundary orientations of the planar facets correspond to the planes with the higher densities of coherent atoms by analyzing the geometrical near coincidence site model.
Relation between the (α+θ) microstructure and the superplastic behavior in ultra-high carbon steels has been studied. The austenitizing, quenching and tempering treatment of pearlite structure produces an (α+θ) microduplex structure with high angle α grain boundaries. The specimen austenitized, quenched and tempered shows much larger superplastic elongation in the tensile tests at 973K than the as warm rolled specimens. This structure also exhibits the superior strength-ductility balance at room temperature.
In the nucleation of intragranular ferrite idiomorphs on the incoherent MnS+V(C, N) complex precipitates in austenite, there is no specific orientation relationship between the ferrite and its austenite matrix indicating that the ferrite transformation texture could be randomized.
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