Basis for the Bauschinger effect in copper single crystals: changes in the long-range internal stress with reverse deformation

Abstract

The long-range internal stresses (LRIS) associated with the Bauschinger effect were investigated using synchrotron X-ray microbeam diffraction and reversed deformation experiments. [100]-oriented Cu single crystals were deformed in compression to approximately − 0.3 true strain, followed by tension to a strain of approximately + 0.02. Two conclusions are arrived at from this work: First, the LRIS are confirmed in this work to be small relative to the applied stress both before and after reversal. Second, the LRIS persist after 2% reversed strain despite a significant drop in the overall dislocation density by dynamic recovery. This appears to satisfy the necessary condition for LRIS to significantly contribute to a Bauschinger effect in materials. The pronounced Bauschinger effect in Cu is probably best rationalized by a combination of both the LRIS and the Orowan–Sleeswyk model that relies on a non-uniform distribution of dislocation obstacles without a substantial LRIS.