Strain Rate Sensitivity of Ultrafine Grained Aluminium Alloy AA6061
The strain rate sensitivity of the aluminium alloy AA6061 has been investigated in a conventional grain sized (CG) state and in two different ultrafine grained (UFG) conditions processed by Equal Channel Angular Pressing (ECAP) for 2 and 6 passes at 100o C. Strain rate jump tests in compression were performed at different temperatures and the strain-rate sensitivity exponent m was determined. The tests were accomplished by microstructural investigations before and after compression testing in CG and UFG conditions. It is shown that all UFG microstructures exhibit strongly increased strain-rate sensitivity (SRS) compared to the CG state. The SRS increases with increasing temperature and is more pronounced for the UFG material processed using 6 ECAP passes. The microstructural investigations show a rather high stability of the grain structure for the UFG conditions up to 250o C. The results are discussed with respect to the relevant deformation mechanisms.
Yuri Estrin and Hans Jürgen Maier
A. Vevecka-Priftaj et al., "Strain Rate Sensitivity of Ultrafine Grained Aluminium Alloy AA6061", Materials Science Forum, Vols. 584-586, pp. 741-747, 2008