Texture Development and Length Changes in Copper Bars Subjected to Free End Torsion

Abstract

Free-end torsion tests were carried out on polycrystalline copper samples at room temperature, 125°C, 200°C and 300°C. The lengths of the samples increased at room temperature and 125°C, but increased and then decreased at 200°C and 300°C. Pole figures were measured on these samples at increasing shear strains up to γ= 11. ODF's were calculated from the pole figures, which enabled the texture development at the two higher temperatures to be distinguished from that observed at the two lower temperatures. Analysis of these ODF's indicates that the low temperature torsion textures are entirely attributable to dislocation glide and can be predicted by means of the conventional texture development programs of crystal plasticity. By contrast, the high temperature textures display evidence for dynamic recrystallization, the occurrence of which seems to be responsible for the shortening. Dynamic recrystallization removes the {100} <110> or C component and strengthens the rotated cube and the 111 <110> or A components.