EFFECT OF SHEAR BANDS ON TEXTURE EVOLUTION IN MIDDLE-HIGH STACKING FAULT ENERGY METALS AS CHARACTERIZED ON MODEL POLYCRYSTALLINE COPPER

Periodic crystal lattice rotations within compact clusters of shear bands (SB), developed in copper (purity of 99.98%), have been characterized to examine the role of lattice re-orientation within grains on slip propagation across grain boundaries. Polycrystalline copper (grain size 50 mu m) was deformed 50% in plane strain compression at room temperature to form two sets of well-defined macroscopic shear bands (MSB). The deformation-induced sub-structures and local changes in crystallographic orientations were investigated by FEG-SEM, equipped with high resolution EBSD. In all the deformed grains examined (within MSBs) a strong tendency to strain-induced re-orientation could be observed. Their crystal lattice rotated in such a way that one of the {111} slip planes became nearly parallel to the direction of maximum shear. A natural consequence of this rotation is the formation of a specific MSB microtexture which facilitates slip propagation across grain boundaries without tiny visible variation in the slip direction although the slip plane did not coincide exactly in the adjacent grains.