| Project/Area Number |
25630300
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| Research Category |
Grant-in-Aid for Challenging Exploratory Research
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| Allocation Type | Multi-year Fund |
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| Research Field |
Structural/Functional materials
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| Research Institution | Tokyo Institute of Technology |
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Principal Investigator |
TAKEYAMA Masao 東京工業大学, 理工学研究科, 教授 (30251622)
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| Project Period (FY) |
2013-04-01 – 2015-03-31
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| Project Status |
Completed (Fiscal Year 2014)
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| Budget Amount *help |
¥4,030,000 (Direct Cost: ¥3,100,000、Indirect Cost: ¥930,000)
Fiscal Year 2014: ¥1,820,000 (Direct Cost: ¥1,400,000、Indirect Cost: ¥420,000)
Fiscal Year 2013: ¥2,210,000 (Direct Cost: ¥1,700,000、Indirect Cost: ¥510,000)
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| Keywords | 相平衡 / 粒界析出 / tP30 / 相安定性 / Fe-Ni-Cr-Mo / Fe-Ni-Cr-Mn / 合金設計 / 固溶軟化 / 状態図 / Fe-Ni-Cr / 耐熱鋼 / 格子安定度 / 構造材料 / 社会基盤構造材料 / TTP図 |
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| Outline of Final Research Achievements |
Phase stability, phase equilibria and the precipitation behavior of σ phase, which has been considered as a detrimental phase, in carbon free Fe-Cr-Ni austenitic heat resistant steels have been examined, in order to seek its new possibilities as a strengthening spices. The stability of the σ phase in Fe-Cr-Ni ternary system increases by the addition of Mo and Mn. Especially, the thermodynamically stable σ phase increase by 300K by Mo addition. Proposed steels designed by newly created database revealed a unique microstructure having 90 % of the grain boundaries of the total grain boundaries are covered by the σ phase after prolonged aging at 1073 K. This result shows a possibility to have a excellent creep rupture strength of the steels by grain-boundary precipitation strengthening. In addition, the σ phase shows solid solution softening by the elements in solution, indicating that alloying can change the nature of σ phase.
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