Material properties under drawing and extrusion with cyclic torsion

Many cold and hot worked metals undergo strain softening and hardening when subjected to cyclic plastic deformation. The degree of strain softening depends on the amount of prior cold work or heat treatment and upon the strain magnitude and cycles applied. In this work, a lead bar was extruded and a copper bar was drawn through a cyclically twisting die in a specifically designed experimental rig. The drawing/extrusion load fluctuated at the same frequency as that of die twisting. The maximum load was equivalent to monotonic deformation when the die was changing direction. The degree of the reduction in load for both the drawing and extrusion depends on the deformation conditions and requires optimisation for the process.