INFLUENCE OF THE SPECIFIC LOCAL MISORIENTATIONS WITHIN SHEAR BANDS ON THE GLOBAL ROLLING TEXTURE FORMATION IN POLYCRYSTALLINE COPPER AND BRASS

摘要

The effect of local misorientations, induced through the development of shear bands, on the global texture in polycrystalline metals deformed by rolling was studied. Since, in model investigations, rolling is as a rule approximated by a plane state of strain, the channel-die compression, satisfying this model assumption, has been applied for comparison.The local orientations inside the macroscopic shear bands and the changes of their geometry in the deformation process are known from single crystals experiments, concerning mainly the C - {112}<111> orientation, which favours the occurrence of macroscopic shear bands in copper and the formation of deformation twins in f.c.c. metals of low stacking fault energy.The experimental studies were performed on samples of fine- and coarse-grained copper and brass, subjected to rolling and channel-die compression in a wide reduction range from 40% to 95%. The analysis of the global texture and local microtexture was based on three-dimensional distribution functions calculated by the direct method from data obtained by X-ray diffraction and TEM measurements. In particular, the differences in the influence of the macroscopic shear bands on the main components of the global texture in pure copper and in a-brass are analysed and discussed.