Effect of ECAP Hot Processing on Grain Refinement and Superplasticity of 1933 Aluminium Alloy
Cold and hot Equal-Channel Angular Pressing (ECAP) is an effective method to refine metallic grains. In this paper, superplastic properties of 1933 aluminium alloy were evaluated and the effect of hot ECAP on grain refinement and superplasticity was investigated. The testing results show that the refinement of grains can not be infinitely increased with the increasing of ECAP passes (or total strain). Under the isothermal ECAP conditions of the present study, optimum ECAP passes for 1933 alloy are 4 passes. The grain size of 1933 alloy was refined from 20~50μm to 7~12μm by means of ECAP for 4 passes at 300°C (route Bc), so its superplasticity was improved. Compared with original samples annealed at 400°C, the superplastic elongation of samples processed by ECAP for 4 passes increases by a factor of 130% about, and the range of superplastic temperature varies from 140°C to 210°C. The optimal superplastic temperature and initial strain rate is 510°C and 3.3×10-4s-1 individually, at which the elongation reaches 262% and the flow stress is 7.8MPa only. In a word, 1933 aluminium alloy can present more excellent superplasticity in wide range of superplastic temperature and strain rate.
H. Z. Guo et al., "Effect of ECAP Hot Processing on Grain Refinement and Superplasticity of 1933 Aluminium Alloy", Materials Science Forum, Vols. 551-552, pp. 193-198, 2007