초미세 결정립 Ti- 6Al- 4V 합금의 저온 초소성 거동 = Low Temperature Superplasticity of Ultra-fine Grained Ti-6Al-4V Alloy

다국어 초록 (Multilingual Abstract)

Superplasticity of ultra-fine grained (UFG) Ti-6A1-4V alloy processed by equal channel angular (ECA) pressing was investigated with the variation of strain rate and temperature. Initial coarse equiaxed grains (11 μm in diameter) were significantly refined to =0.3 μm without changing volume fraction after 4 times of isothermal ECA pressing at 600℃. Tensile tests of both coarse grained specimens and UFG specimens were performed at temperatures of 600℃, 650℃ and 700℃, respectively, and at strain rates of 10^(-4)/s to 10^(-2)/s. UFG structures exhibited considerably higher elongations than those of coarse grained specimens at the same conditions of temperatures and strain rates. The results indicated low-temperature superplasticity (LTS) could be achieved by using UFG structures. Also, it was found in this study that, in spite of non-equilibrium state due to intense plastic straining, grain size were found to be an important factor in controlling overall superplasticity of UFG structure. A plastic instability during superplastic deformation of UFG Ti-6A1-4V alloy was discussed in relation to Hart's criterion.
(Received June 2, 2004)

목차 (Table of Contents)

• Abstract
• 1. 서론
• 2. 실험방법
• 3. 실험결과
• 4. 고찰
• 5. 결론
• 후기
• REFERENCES