EFFECT OF GRAIN-ORIENTATION ON DEFORMATION STRUCTURE IN COLD-ROLLED POLYCRYSTALLINE ALUMINUM

Pure (99.996%) polycrystalline aluminium (grain size about 300 mu m) h as been cold-rolled to reductions in the range from 5 to 50% (epsilon( vm)=0.06-0.80) and the deformation microstructure has been analysed by TEM in a large number of grains. The deformation microstructure is su bdivided by dislocation boundaries having different characteristics de pending on the orientation of the deformed grain. An analysis of the d islocation boundaries based on Frank's formula shows that the majority of the dislocations in the boundaries originate from active slip syst ems predicted by a Schmid factor analysis. Thereby a link is created b etween the microstructural evolution and the macroscopic plastic behav iour. The boundary parameters have also been used in a calculation of the dislocation density and the stored energy for grains of different orientations. These calculations together with measurements of the ang ular misorientation distribution shows that microstructural difference s caused by differences in grain orientation are enhanced as the strai n is increased. (C) 1998 Acta Metallurgica Inc. Published by Elsevier Science Ltd. A[I rights reserved.