Abstract
The crystallographic texture and Vickers hardness which develop during wire-drawing of [001] oriented copper single crystals have been studied experimentally as well by simulations. The experiments revealed orientation changes producing cross-shaped patterns in the {200} pole figures and important variations in the Vickers hardness across the diameter. Metallographic investigations showed the presence of deformation bands perpendicular to the initial 〈100〉 directions. By adopting a model for the velocity field inside the die, simulations have been carried out by using a Taylor type rate sensitive crystal plasticity model, including microscopic hardening. The simulated pole figures show the features of the experimental ones and the predicted stress levels correlate well with the measured hardness data.
Highlights
Cold drawing is an important technological method to obtain wires of small diameter.s
There is an angular dependence, too, because the orientation of the initial crystal with respect to the local flow line depends on the exact location of the flow line within the cross section
During the pole figure measurements, as the whole cross section is illuminated by X-rays, the measured pole figure has to be seen as an average one
Summary
Cold drawing is an important technological method to obtain wires of small diameter.s. If the flow lines are known, they can be introduced into the crystal plasticity model and the hardening state as well as the orientation changes can be readily calculated For this purpose, the flow line model of Altan et al (1992) has been used in the present work as it was already successfully employed in earlier polycrystal modeling of wire drawing by Heizmann et al (1996). The same parameters were employed in the present work, except for one of them: as the present material is not an OFHC copper but a 5 N one, the saturation stress "/’sat was lowered to account for the higher purity; 7"sat- 111 MPa was used in the present simulations For the initialization of the reference resolved shear stresses in Eq (10), the value of ,0 16 MPa was prescribed to each slip system before deformation started
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