2022 Fiscal Year Final Research Report
Deformation Mechanism of Nanostructured Dual Phase Steels Composed of Soft and Hard Phases ~ control of mechanical properties based on heterogeneity
Project/Area Number |
20H00306
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Research Category |
Grant-in-Aid for Scientific Research (A)
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Allocation Type | Single-year Grants |
Section | 一般 |
Review Section |
Medium-sized Section 26:Materials engineering and related fields
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Research Institution | Kyoto University |
Principal Investigator |
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Co-Investigator(Kenkyū-buntansha) |
足立 大樹 兵庫県立大学, 工学研究科, 教授 (00335192)
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Project Period (FY) |
2020-04-01 – 2023-03-31
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Keywords | 金属材料 / 力学特性 / 変形中その場中性子回折 / 不均一ナノ組織 / デジタル画像相関法 / 不均一変形 / 強度 / 延性 |
Outline of Final Research Achievements |
In order to clarify the reason why nano-hetero structured metallic materials composed of hard phase/domain and soft phase/domain sometimes can manage both high strength and good tensile ductility, experimental studies were conducted. We have succeeded in fabricating ferrite and martensite dual-phase (DP) steels with various average grain sizes by applying our originally developed heat treatment process to Fe-2Mn-0.1C alloys. Local strain analysis using the micro-DIC (digital image correlation) method was performed to determine the average plastic strain of each phase during tensile deformation, and in situ neutron diffraction during tensile tests was simultaneously performed to quantitatively elucidate the mechanical interaction between the two phases. Stress-strain responses of each phase in the DP steel could be identified for the first time, and we could clarify the mechanical interaction between soft phase and hard phase quantitatively.
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Free Research Field |
金属材料学
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Academic Significance and Societal Importance of the Research Achievements |
ナノヘテロ組織材料(ナノ二相鋼)の優れた加工硬化の本質と軟質・硬質相間の変形拘束の影響を初めて定量的に解明し、ナノヘテロ組織がなぜ全体として優れた力学挙動を示すのかを明らかにすることができた。これは複雑な組織(ヘテロ組織)を有する高強度金属材料の変形挙動を理解するための重要な基礎的知見を与える点で学術的に重要な知見である。また近年、自動車など輸送機器の燃費向上と地球温暖化ガスの排出削減などのため、構造用金属材料には超高強度と十分な延性・靭性が要求されているが、本研究の成果はそうした革新的構造材料を実現するためにも有益な知見を与え、安全な社会の構築にも資することができる。
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