Mechanical & Materials Engineering, Department of


Date of this Version



Published in Materials Science and Engineering A 374:1-2 (June 15, 2004), pp. 369-373; doi: 10.1016/j.msea.2004.03.034 Copyright © 2004 Elsevier B.V. Used by permission.


“Missing strain,” a discrepancy between the total macroscopic strain and the strain contributed by grain boundary sliding (GBS) during superplastic deformation, appears to exist in previous investigations. In this work, the contri¬bution of GBS (ξGBS) and intragranular strain (ξIG) were simultaneously measured using scratch test conducted on AA7475 samples after deformation at 500 °C at initial strain rate of 10-3 s-1. The result shows that the missing strain results most probably from the neglect of the intragranular strain as well as the anisotropic GBS-induced underesti¬mation of ξGBS. The calculation of ξGBS was re-examined, based on the fact that anisotropic shrinkage of samples along width and thickness during superplastic deformation was noted.