Measurement of Micro Residual Stresses Near the Grain Boundary in Copper Bicrystal

Residual stresses near the grain boundary of a bicrystal were measured by synchrotron radiation of SPring-8 at Japan Synchrotron Radiation Research Institute. A copper bicrystal specimen with a 90-degree tilt boundary was deformed 30% in tension. After the plastic extension, kink bands developed in a deformed matrix along the grain boundary. In this study, we focused on the residual stresses in the deformed matrix and the kink band. Residual stresses were evaluated by the X-ray single crystal measurement method. Stereographic projections were used to determine crystal orientations of deformed regions. Our observation showed that crystal orientations were different between the deformed matrix and the kink band. Residual stresses in the direction along the grain boundary in the deformed matrix and kink band were compressive. Residual stresses in the direction vertical to the grain boundary were seen opposite between the deformed matrix and the kink band.