2015 Fiscal Year Final Research Report
New principle for low-temperature-high-strain-rate superplasticity in Titanium alloy by means of novel microstructural control technique
| Project/Area Number |
25709068
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| Research Category |
Grant-in-Aid for Young Scientists (A)
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| Allocation Type | Partial Multi-year Fund |
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| Research Field |
Material processing/Microstructural control engineering
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| Research Institution | Kagawa University |
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Principal Investigator |
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| Project Period (FY) |
2013-04-01 – 2016-03-31
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| Keywords | 航空機チタン合金 / 超塑性 / マルテンサイト / 超微細粒組織 / 変形機構 |
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| Outline of Final Research Achievements |
This work revealed that ultrafine-grained Ti-6Al-4V alloy (α’-UFG) produced by new type of processing exhibited low-temperature-high-strain-rate superplasticity at the highest level. Herein, dynamic β precipitation from a metastable single α starting microstructure (occurred under deformation) contributed to a stress-accommodation mechanism. Accompanied by this dynamic β-precipitation, grain boundary sliding mode of theα’-UFG dynamically evolved from the type of the Ball-Hutchison model to the type of the Gifkins Core-Mantle model. In addition, high ductility at high temperature is also obtained in the martensite starting microstructure. This is due to the frequent occurrence of dynamic recrystallization during deformation, resulting in enhancement of stress-accommodation and grain-boundary-sliding. Similar behavior has been also confirmed in Ti-6242 alloy. So, formation of metastable starting microstructure was found to be new concept for enhancing the superplastic property.
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| Free Research Field |
金属組織学・強度学
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