| Project/Area Number |
22K14510
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| Research Category |
Grant-in-Aid for Early-Career Scientists
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| Allocation Type | Multi-year Fund |
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| Review Section |
Basic Section 26050:Material processing and microstructure control-related
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| Research Institution | Osaka University |
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Principal Investigator |
HOU YUYANG 大阪大学, 接合科学研究所, 助教 (60905933)
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| Project Period (FY) |
2022-04-01 – 2024-03-31
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| Project Status |
Completed (Fiscal Year 2023)
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| Budget Amount *help |
¥4,550,000 (Direct Cost: ¥3,500,000、Indirect Cost: ¥1,050,000)
Fiscal Year 2023: ¥2,210,000 (Direct Cost: ¥1,700,000、Indirect Cost: ¥510,000)
Fiscal Year 2022: ¥2,340,000 (Direct Cost: ¥1,800,000、Indirect Cost: ¥540,000)
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| Keywords | Stainless steel / Weld metal / Nucleation / Grain refinement / Solidification / Tensile property / Oxide / TiN / δ-ferrite / Austenite / Welding Metallurgy / Stainless Steel / Equiaxed Solidification / Microstructural / Mechanical property |
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| Outline of Research at the Start |
In this research, the effective oxide will be fully investigated for primary ferrite nucleation, structure evolution, and mechanical property of SUS304 stainless steel weldment. The optimized compositional will be proposed to achieve the research purpose. The solidification and strengthening mechanism will be evaluated by experimental identification and theoretical calculation. This research will propose new strategies and knowledge in grain refinement, strengthening, and toughening.
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| Outline of Final Research Achievements |
In this study, primary ferrite nucleation (PFN) was accelerated by Oxide+TiN to achieve the equiaxed δ-ferrite of stainless steel with FA solidification mode. The effective oxide for PFN was revealed as Ti2O3, (Al,Ti)Ox, and MgAl2O4, where MgAl2O4 is the optimal oxide. Under the double side bead on plate welding, the PFN was achieved by Ti-Al-Mg alloying, and significantly transformed the δ-ferrite form network morphology to random Vermicular-δ. However, PFN have limited influence on austenite formation under FA mode because the formation and growth of austenite were independent to the primary ferrite. The UTS and elongation was deteriorated by PFN, because the formation of fragment TiN initiated the tensile fracture.
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| Academic Significance and Societal Importance of the Research Achievements |
This research developed a new method for primary ferrite nucleation in stainless steel with FA mode. These results offer an effective method for the control of weld microstructure. The fracture mechanism offers an important guidance for further improvement of mechanical performance.
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