| Project/Area Number |
17K17581
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| Research Category |
Grant-in-Aid for Young Scientists (B)
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| Allocation Type | Multi-year Fund |
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| Research Field |
Material processing/Microstructural control engineering
Structural/Functional materials
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| Research Institution | Tohoku University |
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Principal Investigator |
Sato Mitsutaka 東北大学, 金属材料研究所, 助教 (10547706)
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| Research Collaborator |
Furuhara Tadashi
Miyamoto Goro
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| Project Period (FY) |
2017-04-01 – 2019-03-31
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| Project Status |
Completed (Fiscal Year 2018)
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| Budget Amount *help |
¥4,420,000 (Direct Cost: ¥3,400,000、Indirect Cost: ¥1,020,000)
Fiscal Year 2018: ¥2,080,000 (Direct Cost: ¥1,600,000、Indirect Cost: ¥480,000)
Fiscal Year 2017: ¥2,340,000 (Direct Cost: ¥1,800,000、Indirect Cost: ¥540,000)
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| Keywords | フェライト変態 / 窒素鋼 / 相界面析出 / エネルギー散逸 / 窒素オーステナイト / TRIP鋼 / 構造・機能材料 / 相変態 |
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| Outline of Final Research Achievements |
In this research, ferrite transformation behavior of Fe-N alloy and the effect of alloying element were investigated using pure iron and 1 mass% of Mn, Mo and Cr added alloy. The nitrogen austenite was obtained by nitriding method, and then, the nitrided samples were isothermally treated in the α + γ two-phase region for several period of time.
The two types of morphology of AF and WF were obtained with changes in the driving force of ferrite transformation. The AF was nucleated from the prior austenite grain boundaries, and the AF has K-S OR with one side of the adjacent prior austenite grains and grew into the grains having non K-S OR. On the other hand, the WF had the K-S OR with the prior austenite grain. Transformation was retarded by the addition of Mn and Mo. In the Cr added alloy, the ferrite transformation progressed with the interface precipitation of CrN.
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| Academic Significance and Societal Importance of the Research Achievements |
本研究により、Fe-N合金におけるフェライト変態はこれまでに報告されている炭素鋼における変態挙動と良く似た挙動を示し、炭素鋼での知見を基にFe-N系合金における変態挙動を理解することが可能であることが明らかとなった。一方で、窒化物形成能の高い元素であるCrを添加した試料では，CrN の相界面析出が生じることが明らかとなった。炭素鋼では相界面析出によりフェライトを強化した複相鋼板は高強度-高延性材料として現在幅広く利用されている鋼種であり、本研究の結果は窒素を利用した窒化物析出による新しい高強度鋼の開発へとつながる。
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