Texture Development and LengthChanges in Copper Bars Subjected toFree End Torsion

Abstract

Free-end torsion tests were carried out on polycrystalline copper samples at room temperature, 125C, 200C and 300C. The lengths of the samples increased at room temperature and 125C, but increased and then decreased at 200C and 300C. Pole figures were measured on these samples at increasing shear strains up to ), 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.

Modeling of deformation induced anisotropy in free-end torsion

“…The first shows a decreasing slope of the axial strain curve. The second shows a linear growth of the axial strain, which corresponds to measurements by Toth et al (1992). For =1 the axial strains saturate as it can also be observed in experiments (Grewe and Kappler, 1964;Witzel, 1981).…”

Length changes and texture prediction during free end torsion test of copper bars with FEM and remeshing techniques

“…The effect of sample temperature during free end torsion of copper bars was analysed experimentally in Toth et al (1992). Lengthening was observed during the torsion at room temperature and 125 °C.…”

“…On the other hand, the shortening observed under particular experimental conditions can be attributed to dynamic recrystallization during torsion (Toth et al, 1992;Rohatgi et al, 1995;Weber et al, 2000).…”

“…Texture measurements have been carried on before and during experimental torsion processes (see e.g. Toth et al, 1992Toth et al, , 1991Qods et al, 2005). Beside, plastic anisotropy models based on texture evolution have been applied for the Swift effect prediction of twisted materials (Toth et al, 1990;Wu, 2003;Wu et al, 1996;Qods et al, 2005;Toth and Jonas, 1989).…”

“…The prediction of the Swift effect and the texture evolution are compared to experimental results from Toth et al (1992).…”