2017 Fiscal Year Annual Research Report
Ultra-grain refinement as prevention against hydrogen-assisted crack propagation
| Project/Area Number |
16K17981
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| Research Institution | Kyushu University |
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Principal Investigator |
マカドレ アルノー 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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| Keywords | hydrogen embrittlement / austenite / grain refinement / steel |
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| Outline of Annual Research Achievements |
The metastable austenitic stainless steel was produced with six different grain sizes, from 1 micron to 21 microns. Hydrogen was introduced in the steel with different hydrogen gas pressures: 10, 40 and 100 MPa.
Tensile tests showed an overall decrease of the tensile strength for all grain sizes, the decrease of tensile strength occurred at the highest hydrogen content (100 MPa hydrogen gas) only for the smaller grains (1 micron). The 1 micron grains still maintained a tensile elongation of 30%.
In this metastable austenite, large hydrogen contents stabilize the austenitic phase. At low strains (true strain < 0.1), with the highest hydrogen content, there is no strain-induced martensite. This was explained with an increase of slip planarity, with less martensite nuclei being formed.
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