| Project/Area Number | 07555666 |
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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 | Osaka University |
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Principal Investigator |
TOYODA Masao Osaka University, Faculty of Engineering, Professor, 工学部, 教授 (00029191)
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| Co-Investigator(Kenkyū-buntansha) |
SUZUKI Suichi Sumitomo Metal Ind., Steel Sheet & Plate Planning Section, Manager, 鹿島製鉄所・厚板管理室, 室長(研究者)
NAGAE Moriyasu NKK Corp., Materials and Processing Research Center, Manager, 総合材料技術研究所・福山研究所, 課長(研究者)
KAWABATA Fumimaru Kawasaki Steel Corp., Heavy Steel Products Research Dept., Manager, 鉄鋼研究所・厚板・条鋼研究室, 課長(研究者)
HAGIWARA Yukito Nippon Steel Corp., Steel Research Lab., General Manager, 鉄鋼研究所, 部長(研究者)
MINAMI Fumiyoshi Osaka University, Faculty of Engineering, Associate Professor, 工学部, 助教授 (60135663)
SHIMIZU Masato Kobelco Research Ins., Contracted Research Division, Manager
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| Project Period (FY) |
1995 – 1997
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| Project Status |
Completed(Fiscal Year 1997)
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| Budget Amount *help |
¥1,800,000 (Direct Cost : ¥1,800,000)
Fiscal Year 1997 : ¥700,000 (Direct Cost : ¥700,000)
Fiscal Year 1996 : ¥1,100,000 (Direct Cost : ¥1,100,000)
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| Keywords | Dual-Phase Steels / Local Heterogeneity / Brittle Fracture / Fracture Toughness / Controlling Microstructure / Stress-Strain analysis / Local Approach / Material Design / 破壊靭性 / 高強度鋼 / 溶接熱影響部 / 局部的劣化部 / CTOD試験 / 応力・歪解析 |
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| Research Abstract |
This study discussed the transfer of local stress fields in microstructures to fracture property evaluation of structural steels. Initiation behavior of brittle microcrack in dual-phase steels was mainly focused. The Weibull stress employed in the local approach is available for the evaluation of fracture driving force of each microstructure in dual-phase steels. The idea in this procedure is the integration of local stress in the microstructure responsible for fracture initiation. The local stress in dual-phase steels can be different considerably from a macroscopic stress obtained from the global analysis of specimen. Generally, the high-strength phase bears larger stress than the low-strength phase, which means that fracture property evaluation based on the global stress field is not always reliable. The local stress in the microstructure is affected by the morphology of second phase and matrix. Increase in strength and slenderness of hard phase leads to elevation of fracture driving force of the hard phase. The stresses in low-strength phase can be relaxd to a large extent, provided that the low-strength phase is enclosed by the high-strength phase. These microscopic characteristics of stress fields are important in the fracture control design of structural steels. The Weibull stress is expected as a measure to link between microscopic and macroscopic aspects of fracture.
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