| Project/Area Number |
63550508
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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 |
金属加工(含鋳造)
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| Research Institution | HIROSHIMA UNIVERSITY |
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Principal Investigator |
OHMORI Masanobu Fac. of Engineering, Professor, Hiroshima Univ., 工学部, 教授 (90034321)
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| Co-Investigator(Kenkyū-buntansha) |
ITOH Misao Fac. of Engineering, Lecturer. Hiroshima Univ., 工学部, 講師 (50144879)
YOSIDA Fusahito Fac. of Engineering, Associate Prof. Hiroshima Univ., 工学部, 助教授 (50016797)
YANAGISAWA Osamu Fac. of Engineering, Associate Prof. Hiroshima Univ., 工学部, 助教授 (50034393)
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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 |
¥1,800,000 (Direct Cost: ¥1,800,000)
Fiscal Year 1989: ¥300,000 (Direct Cost: ¥300,000)
Fiscal Year 1988: ¥1,500,000 (Direct Cost: ¥1,500,000)
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| Keywords | Nickel-Chromium Alloys / Intermediate Temperature Brittleness / Grain Boundary Ductile Fracture / Strain Rate / Ni-Cr Powder Sintered / 粒界延性破壊 / 粒界割れ / 圧延加工性 / セレーション |
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| Research Abstract |
High temperature plastic workability of pure nickel, 80%Ni-20%Cr alloy, 50%Ni-50%Cr alloy and a sintered material made from gas atomized powder of 50%Ni-50%Cr alloy were investigated in vacuum by tension teal. All specimens lost their ductility at temperatures around about 1100K. This less ductility, i.e., the intermediate temperature embrittlement was led by the grain boundary ductile fracture.
The intermediate brittleness disappeared in the pure nickel deformed at a strain rate higher than about 10^<-1> s^<-1>. Also the brittleness in the nickel-chromium alloys became slight with increasing strain rate. The brittleness behavior in the present specimens was quite similar to the behavior found in copper and its alloys.
The less ductility occurring in the nickel-chromium alloy, i.e., a fundamental system of nickel-base alloys, was conclusively considered to be due to viscous nature of crystal grain boundaries.
High temperature workability of sintered material made from nickel-and chrolnium-powder was also examined. Good workability was found in a temperature range of 700 to 900K. However, the ductility at temperatures lower and higher than 700-900K was very poor. The poor ductility at the lower temperatures came from brittle fracture in the chromium particles. At the higher temperatures, on the other hand, the tensile stress at the interface between nickel and chromium particles, originated from a large difference between thermal expansion coefficients of both particles, led to less ductility.
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