Evaluation of the superplastic potential in commercial aluminum alloys through equal-channel angular pressing

Since Equal-Channel Angular (ECA) pressing offers significant advantages for grain refinement and meets the requirements for superplasticity, it has been chosen as a basic tool of material processing for this study. The effect of ECA pressing on superplasticity of commercial aluminum alloys was investigated by changing some of the basic parameters for ECA pressing such as the pressing routes, the number of pressings and the pressing temperatures.; The ECA pressing was applied to pure aluminum and it is determined that the variations of microhardness are large throughout the length of the pressed billet for lower numbers of passes but a very uniform microstructure is obtained throughout the billet after higher numbers of passes.; Two new combination pressing route, C-B_C and B_C-C, were designed, applied to both pure aluminum and an Al-2024 alloy and compared to route B_C. It is concluded that route B_C is the most reliable pressing route because the two combination routes have no clear advantage in terms of superplasticity over route B_C.; The effect of small amounts of addition of Sc and Zr into pure aluminum and an Al-Mg binary alloy was investigated. It is determined that the addition of both Sc and Zr at the same time is more effective in promoting superplasticity than the addition of only one element.; The ECA pressing was applied to commerical aluminum alloys such as Al-2024, Al-2004 and Al-1420 alloys. The ECA pressing at high temperatures always produced superior superplasticity over the ECA pressing at room temperature. After ECA pressing of the commercial Al-2024 and Al-2094 alloys, furthermore, the optimum superplastic conditions were shifted to both a lower testing temperature and a higher imposed strain rate. An exceptional high strain rate superplasticity (HSR SP) was obtained for every aluminum alloy. For example, an elongation of ∼950% was recorded at a temperature of 673 K with a strain rate of 1 s−1 when the Al-1420 alloy was ECA pressed to a strain of ∼12.