中国有色金属学报(英文版)
Transactions of Nonferrous Metals Society of China
Vol. 4 No. 1 March 1994 |
(Metal Forming Department; Northeastern University; Shenyang 110006; China)
Abstract:Effects of current pulses on superplasticity of cold rolled and 500 ℃ , 30min recrystullizedstates of 2091 Al-Li alloy were investigated. The tension results showed that current pulses madethe elongation of 500 ℃, 30 min recrystallized specimens increase from δ= 290% to δ=390%, and the optimum strain rate of superplastic deformation in cold rolled specimens incrcasefrom εopt= 5. 0 × 10-3 s-1 to εopt= 8. 33 × 1 0-3 s-1 , with the same εmax. Investinnations of me-chanical behaviors indieated that current pulses enhanced the stress strain rate sensitivity expo-nent (500 ℃,30min recrystallized state) and pushed the value of mmax. towards high strain rateregion (cold rolled state). Electron probe analyses showed that current pulses made the soluteatom Cu distribute more homogeneously. It was indicated that the enhancement of m value athigh strain rate by applying current pulses was because homogeneously distributed solute atomsincreased the stress strain rate sensitivity.
Key words: Al-Li alloy current pulse superplasticity