2013 Fiscal Year Final Research Report
Creep strengthening and weakening mechanisms by martensite lath in high Cr ferritic heat-resistant steel
| Project/Area Number |
24760576
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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 |
Structural/Functional materials
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| Research Institution | Kyushu University |
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Principal Investigator |
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| Project Period (FY) |
2012-04-01 – 2014-03-31
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| Keywords | フェライト系耐熱鋼 / クリープ変形 / 強化機構 / ラスマルテンサイト / 転位 / 粒界上析出物 / 電子顕微鏡 / 結晶方位解析 |
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| Research Abstract |
In this study, we clarified creep strengthening and weakening mechanisms by martensite lath structure in high Cr ferritic heat resistant steel. Firstly, the interaction of dislocations and lath boundaries were observed with in-situ tensile test in high-voltage transmission electron microscope. Then, lath structure coarsening behavior during creep deformation was evaluated by the crystal orientation analysis. From these results, we concluded that lath structure is a dominant factor of creep strength in high Cr ferritic heat resistant steel. In addition, in order to understand the mechanism of improvement of lath structure stability by precipitates formed on grain boundary, the size and the density of precipitates on each grain boundary were estimated using the microstructural observation. Those parameters of precipitates obviously depended on the grain boundary character.
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