| The superplastic deformation behavior of Ti-6Al-4V alloy with two different microstructures, a banded microstructure with continuous a phase and an equiaxed microstructure, was investigated by performing both strain-rate-change and constant-strain-rate tests in a longitudinal direction. It was found that the continuous a phase significantly affect the superplastic deformation behavior of the alloy. At 925℃ the continuous α phase remained unbroken during deformation causing higher flow stress at lower strain rate range and tow value of strain rate sensitivity, m. At lower temperature below 880℃, on the other hand, the α phase was broken up to recrystallize dynamically resulting in higher m values at 850 and 880℃. The m values of the cross rolled materials which do not have the continuous α phase steadily increased with temperatures up to 880℃ and did not show a significant decrease at 925℃ contrary to the unidirectionaliy rolled materials. |
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