| Project/Area Number |
63550478
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| Research Category |
Grant-in-Aid for General Scientific Research (C)
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| Allocation Type | Single-year Grants |
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| Research Field |
Physical properties of metals
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| Research Institution | Tottori University |
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Principal Investigator |
OKA Muneo TOTTORI UNIV., DEPT., MECHANICAL ENG., PROFESSOR, 工学部, 教授 (60029866)
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| Co-Investigator(Kenkyū-buntansha) |
HAYAKAWA Motozo TOTTORI UNIV., DEPT., MECHANICAL ENG., ASSISTANT PROFESSOR, 工学部, 助教授 (60093621)
OKAMOTO Hisaki TOTTORI UNIV., DEPT., MECHANICAL ENG., RESEARCH ASSOCIATE, 工学部, 助手 (30029889)
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| Project Period (FY) |
1988 – 1989
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| Project Status |
Completed (Fiscal Year 1989)
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| Budget Amount *help |
¥1,900,000 (Direct Cost: ¥1,900,000)
Fiscal Year 1989: ¥400,000 (Direct Cost: ¥400,000)
Fiscal Year 1988: ¥1,500,000 (Direct Cost: ¥1,500,000)
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| Keywords | LOWER BAINITE / ISOTHERMAL TRANSFORMATION / ORIENTATION RELATIONSHIP / PHENOMENOLOGICAL THEORY / 高炭素鋼 / マルテンサイト |
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| Research Abstract |
The lower bainite transformation in five hypereutectoid steels (0.85 to 1.87 wt pct C) has been studied in the temperature range between 623 and 453 K by means of metallographic techniques. This paper brought conventional lower bainite into focus. The habit planes of ferrite and cementite platelets in lower bainite of a 1.10 wt pct C steel were close to (496)_f and between (101)_b and (112)_b, respectively (subscripts f, b, and c refer to the fcc austenite, bcc bainitic ferrite, and bainitic cementite, respectively). On the other hand, those in 1.80 and 1.87 wt pct C steels were close to (384)_f and (101)_bb, respectively. The orientation relationship between austenite and bainite ferrite was the Kurdjumov-Sachs (K-S) relation and that between ferrite and cementite was the Isaichev relation for a 1.80 wt pct C steel. Application of the phenomenological theory of martensitic transformation to lower bainite in 1.80 and 1.87 wt pct C steels indicated that the lower bainite crystallography could be described by use of the (101)[1^^-1^^-1]_b system as the inhomogeneous shear, instead of the (112)[1^^-1^^-1]_b system. The experimental and theoretical results suggest that lower bainite and martensite in 1.80 and 1.87 wt pct C steels have the same transformation inhomogeneity as the (101)[1^^-1^^-1]_b system and their transformation mechanisms might be similar. The formation mechanism for lower bainite in a 1.10 pct C steel is still under consideration.
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