| Project/Area Number |
10355029
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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 | 展開研究 |
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| Research Field |
Material processing/treatments
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| Research Institution | Toyohashi University of Technology |
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Principal Investigator |
KOBAYASHI Toshiro Toyohashi University of Technology, 工学部, 教授 (90023324)
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| Co-Investigator(Kenkyū-buntansha) |
KURIKUMA Tsutomu Toyohashi University of Technology, 技術開発研究所, 主担当研究員
MORITA Shigeki Toyohashi University of Technology, 工学部, 教務職員 (00314089)
TODA Hiroyuki Toyohashi University of Technology, 工学部, 助教授 (70293751)
井上 直也 豊橋技術科学大学, 工学部, 教務職員 (80293760)
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| Project Period (FY) |
1998 – 2000
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| Project Status |
Completed (Fiscal Year 2000)
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| Budget Amount *help |
¥23,900,000 (Direct Cost: ¥23,900,000)
Fiscal Year 2000: ¥3,600,000 (Direct Cost: ¥3,600,000)
Fiscal Year 1999: ¥1,100,000 (Direct Cost: ¥1,100,000)
Fiscal Year 1998: ¥19,200,000 (Direct Cost: ¥19,200,000)
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| Keywords | ADI / thermomechanically treatment / toughening / austempering temperature / γ-pool / fracture toughness / graphite size / austempering reaction / 動的破壊靭性値 / 靭性 / 球状黒鉛鋳鉄 / 強じん化 / マルテンサイト変態 / 計装化シャルピー衝撃試験 / 破壊じん性 |
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| Research Abstract |
In the fiscal year 1998, effects of rolling reduction, austempering temperature and its time during thermo-mechanical treatments on toughness of the ADI were investigated. In the fiscal year 1999, in order for the optimization and efficiency of the thermo-mechanical treatment conditions, effects of graphite diameter and austempering temperature on toughness were investigated. In the fiscal year 2000, effects of rolling reduction and stability of Austenite on strength and toughness were evaluated.
It has been certified that the effects of the graphite size on the fracture toughness of the ADI is almost negligible.. On the other hand, according to the analysis of the relationship between the gamma pool and toughness, the gamma pool is predominant over the fracture toughness properties of the ADI.Although shear bands which are formed in-between the graphite nodules act as a nucleation site for the beinitic ferrite effectively, it sometimes causes fracture there. It has been concluded that
… More
large graphite nodules are preferable for the practical application of the thermo-mechanical treatment. As for the absorbed energy, the maximum value was obtained for the rolling reduction of 40% and austempering time of 14.4ks, while the fracture toughness reached maximum for the rolling reduction of 60%. The tensile strength exceeds 1000MPa when the rolling reduction ranges 0 to 4O%, and the elongation reached the maximum for the 4O% reduction. The residual Austenite decreased and its stability increased within the range and deformation-induced Martensite transformation disappeared in the high rolling reduction range.
Comprehensively speaking, the rolling reduction of 40% is concluded as the best condition from a viewpoint of the balance between strength and toughness. Strength becomes higher in the lower rolling reduction side, while toughness becomes superior in the higher side. The optimization of characteristics of respective portion becomes possible together with near-net-shape forming by utilizing the knowledge obtained above. By performing microstructural and component designs of the ductile cast irons on the basis of the above-mentioned concepts, predominance over the traditional steel can be recognized which enables substitution from the steels. Less
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