DIC study of inhomogeneous strain around grain boundaries in plastically deformed metals

Abstract

The strain measurement by conventional two-dimensional digital image correlation (DIC) method was applied to the strain inhomogeneous in the vicinity of grain boundaries of pure aluminum polycrystals. Even if a polycrystal is deformed uniformly in macroscopic view, nonuniform deformation occurs in microscopic scale. It is important to investigate local plastic strain concentration at grain boundaries in metals and alloys because the accumulation of dislocations near the grain boundaries can generate microcracks. Therefore, the purpose of this study is to measure the strain distribution in such microscopic dimension using digital image correlation method, which is a non-contact strain measurement by means of digital image processing. It was found that DIC measurement in submicron region is possible by attempting to refine the random pattern speckle. Similarly, indentation hardness near grain boundary after plastic deformation was examined by using micro-load indentation testing with a Berkovich indenter.