| Effect of the RI-ITMT variations on grain refinement and the superplasticity of 7475 aluminum alloy has been studied. The increased number of warm rolling passes contributed for better grain refinement, that is the average grain diameter of 7.5㎛ was obtained. As the solution treatment time increased, the distribution and the size of secondary particles became more uniform and finer, respectively, and the superplasticity was enhanced. The maximum superplastic elongation of this study was 2000% at 516℃, and at the deformation rate of 1.7 × 10^(-3)/s. The attained superplasticity of this study is much higher than any of the previously published results on 7475 and 7075 alloys. Cold rolling process, instead of the warm rolling of the conventional RI-ITMT, has resulted a little decreased superplasticity. However the superplastic elongation was still quite high. |
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