Strain rate sensitivity of equal-channel angularly pressed Sn-5Sb alloy determined by shear punch test

The strain rate sensitivity (SRS) of a fine-grained Sn-5 wt% Sb alloy, processed by equal-channel angular pressing (ECAP), was investigated by shear punch testing (SPT) at room temperature. The microstructural homogeneity increased with increasing the number of ECAP passes, and the grain size decreased from 3.2 to 2.5 mu M, as the number of passes increased from 1 to 4. Results showed that the deformation response of the material after 4 ECAP passes conforms to regions I, II and III, typical of superplastic behavior. In region II, the SRS index of the shear yield stress was significantly strain dependent, being 0.23 and 0.57, after 1 and 4 passes, respectively. The high SRS index of 0.57 is indicative of a superplastic deformation behavior dominated by grain boundary sliding. (C) 2013 Elsevier B.V. All rights reserved.