Re-examination of “missing strain” during superplastic deformation of AA7475

Authors

M. J. Tan, Nanyang Technological University, Singapore
C. L. Chen, Nanyang Technological University, 50 Nanyang Avenue, Singapore 639798, Singapore
Namas Chandra, University of Nebraska-LincolnFollow

Document Type

Article

Date of this Version

6-15-2004

Comments

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.

Abstract

“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 (ξ_GBS) and intragranular strain (ξ_IG) 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 ξ_GBS. The calculation of ξ_GBS was re-examined, based on the fact that anisotropic shrinkage of samples along width and thickness during superplastic deformation was noted.