1996 Fiscal Year Final Research Report Summary
Refining Technics for Improving Ductility and Embrittling Factors of Corrosion-Resistant Fe-Al Alloy
| Project/Area Number |
07650862
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| Research Category |
Grant-in-Aid for Scientific Research (C)
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| Allocation Type | Single-year Grants |
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| Section | 一般 |
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| Research Field |
Metal making engineering
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| Research Institution | Muroran Institute of Technology |
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Principal Investigator |
KATAYAMA Hiroshi Muroran Institute of Technology, Department of Materials Science and Engineering, Prof., 工学部, 教授 (90002881)
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| Co-Investigator(Kenkyū-buntansha) |
TAYU Yoshinori Muroran Institute of Technology, Department of Materials Science and Engineering, 工学部, 助手 (20250524)
MOMONO Tadashi Muroran Institute of Technology, Department of Materials Science and Engineering, 工学部, 助教授 (10002940)
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| Project Period (FY) |
1995 – 1996
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| Keywords | high Al steel / corrosion-resistant steel / ductility improvement / embrittling factors / Fe-Al complex carbide / carbon fixation / environmental embrittlement / Al-Si steel |
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| Research Abstract |
In the present study, experiments were conducted in order to make clear the embrittling factors of high Al steel and to establish their improvement technics. The results are summarised as follows :
1) In the case of ultra-low carbon steel, the hardness and tensile strength increased with the increase of Al content, whereas the elongation decreased. The elongation of 10mass% Al steel varied from about 2 to 15%.
2) With the increase of C content in 10mass% Al steel, the hardness increased. However, the tensile strength and elongation decreased, and the alloy steel containing 0.09mass%C ruptured during the manufacture of specimen for tensile test. Many needle-like precipitates were observed within the inside of crystal grains and along their boundary and identified as Fe3AlC phase by EPMA analysis. The embrittlement of high Al steel with increasing C content seemed to be attributed to the fact that the above complex carbide precipitated along the boundary of crystal grain.
3) In order to fix carbon as stable carbide, Ti and Zr were added to the 10mass% Al steel containing carbon. The increase of Ti content converted Fe3AlC to TiC and resulted in some improvement of ductility. While Zr addition refined the grain size, it assisted the embrittlement because of the formation of network composed of Fe2Zr.
4) Ca, Ce and commercial refining agent had no effect on the ductility.
5) Based on the experimental results and literature survey, it was concluded that the embrittlement of high Al steel cannot be prevented essentially, because high Al steels are susceptible to environmental embrittlement in a moisture atmosphere.
6) Finally, the effect of Si addition on mechanical properties of 5mass% Al steel was investigated. The 5mass%Al-1mass%Si steel had acceptable ductility and seemed to have a high order of resistance to chloride.
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