Plastic anisotropy in aluminium drawn tubes

Abstract

Developments of plastic anisotropy in aluminium tubes are investigated experimentally and theoretically. Asreceived drawn tubes are tensioned or twisted to get speciments having different anisotropies. The tubes are cut and extended into flat sheets. The surfaces are removed mechanically and electorochemically into half thickness. The anisotropy is evaluated by flow stress and r-value of tensile tests in various directions in a sheet. Crystallographic textures are detected by X-ray diffraction, from which crystal orientations are determined and then incorporated into the finite element polycrystal model. The predicted results of anisotropy by numerical tensile tests are compared with the above experiments. If a tube specimen is isotropic, its flow stress of simple torsion should be less than that of simple tension. However, the present as-receieved drawn tube shows the reverse tendency. This fact is confirmed theoretically on the basis of averaged anisotropy through thichness.