STRAIN RATE SENSETIVITY OF EQUAL-CHANNELANGULARLY PRESSED S-5Sb ALLOY DETERMINED BY SHEAR PUNCH TEST

The strain rate sensitivity indices of a fine-grained Sn-5 wt.% Sb alloy processed by equal-channel angular pressing (ECAP), were investigated by shear punch testing (SPT) at room temperature. This localized testing technique is capable of acquiring reliable information on the shear deformation behavior of materials at different strain rates. Results showed that the strain rate sensitivity of the alloy was significantly strain dependent, increasing from 0.15 after 1 pass to 0.6 after 4 passes of ECAP. The observed behavior is attributed to the microstructural changes which occur during progressive deformation in the ECAP process. The microstructural homogeneity increased with increasing the number of ECAP passes, and the grain size decreased from 11 pm after 1 pass to 2.5 um after 4 passes of ECAP. The deformation response of the material after 4 passes of ECAP was characterized by strain rate sensitivity indices of o.1 to 0.6, which conforms to regions I, II and III, typical of superplastic behavior.

کلیدواژه ها:

Strain rate sensitivity ، ECAP ، Shear punch test ، Fine grain