Microtexture and non-homogeneity of deformation at planar smear tests of Cu and Cu-based alloys

The research has been carried out concentrating on non-homogeneity of strai n localization in the form of shear bands with reference to texture investi gation by X-ray method, electron back scattering diffusion (EBSD) method an d microstructural observations. The shearing in the plane of sheet and up t o the point of final rupture was performed by means of a shear apparatus on sheet samples of copper, CuA18 bronze and CuZn37 brass in various initial mechanical states. Optical examination of strain markings in cold-rolled Cu samples revealed the formation of regular shear zones; whereas, in the cas e of cold-worked CuZn37 brass we have observed non-regular and stepped shea r zones. Crystallographic textures determined by X-ray pole figure method r evealed increasing dispersion of the crystallite orientation; the number of crystallites rotating around the direction of shearing increased. Optical examination was completed by the Orientation Imaging Microscopy (OIM) obser vations, based on Electron Back Scattering Diffusion (EBSD) technique. The rotation of crystallites, registered by this technique was less clear than that found by X-ray measurement, Similarly to texture observations, pattern s of microstructure deduced from EBSD technique were less clear in comparis on with optical microstructure photographs. Transmission electron microscop y (TEM) observations of sheared samples of copper have shown the formation of cellular structure of dislocation elongated in the shear direction; in t he case of cold-worked brass we have noted the shear banding on the backgro und of twin+matrix sets. The influence of alloying and initial mechanical state on the evolution of non-homogeneity of deformation in the course of planar shearing of sheets i s discussed.