微視的な塑性ひずみ分布と結晶方位差の関係

抄録

  The correlation between local misorientation and plastic strain induced in polycrystalline copper was investigated. A specimen was subjected to a tensile test in order to introduce plastic strain. From changes in surface images of the specimen during the test, distribution of plastic strain was identified by using the image correlation technique, which derives the strain distribution by image processing. Local misorientations of the strained specimen were measured using electron backscattering diffraction and their spatial distribution was compared with that of plastic strain. The plastic strain was inhomogeneous on a microstructural scale, although uniform macroscopic tensile strain was induced. The maximum local strain was almost twice the average strain and the distribution depended on the microstructure. The grain orientation spread (GOS), which was calculated as the average misorientation among all crystal orientations within a grain, was found to correlate well with grain-averaged plastic strain, although the local misorientation between neighboring points showed poor correlation. The misorientations between neighboring points correlated well with dislocation density introduced by deformation rather than with local plastic strain. It was concluded that, in order to represent the microstructural scale deformation, the strain should be defined not only by deformation per unit length, but also by the dislocation density.