| Project/Area Number |
16K17981
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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 |
Materials/Mechanics of materials
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| Research Institution | Kyushu University |
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Principal Investigator |
MACADRE ARNAUD 九州大学, カーボンニュートラル・エネルギー国際研究所, 学術研究員 (20635891)
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| Project Period (FY) |
2016-04-01 – 2018-03-31
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| Project Status |
Completed (Fiscal Year 2017)
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| Budget Amount *help |
¥3,120,000 (Direct Cost: ¥2,400,000、Indirect Cost: ¥720,000)
Fiscal Year 2017: ¥1,170,000 (Direct Cost: ¥900,000、Indirect Cost: ¥270,000)
Fiscal Year 2016: ¥1,950,000 (Direct Cost: ¥1,500,000、Indirect Cost: ¥450,000)
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| Keywords | hydrogen embrittlement / austenite / grain refinement / steel / 環境材料 / 水素 |
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| Outline of Final Research Achievements |
Grain size refinement led to a large increase of yield stress. Hydrogen charging at different hydrogen pressures (10, 40 and 100 MPa) led to a hydrogen-induced decrease of ductility in the alloy. The ultra-fine grain material (1 micron grains) still retained an elongation of 30% under the highest hydrogen content. There is a solid solution strengthening effect of hydrogen. Hydrogen embrittlement requires larger hydrogen contents in smaller grained material. There was no evidence of cracking of martensite-austenite boundaries, i.e. martensite transformation did not appear as a factor for susceptibility to hydrogen. Large solute hydrogen contents delay the formation of strain-induced martensite and completely cancel it at low strains. There was no effect of grain size on strain-induced martensite, with or without hydrogen. Finally, cracking in small grains seems to be dominated by ductile tensile overload while cracking in large grains is dominated by hydrogen-induced crack propagation.
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