Enhancing mechanical properties of wires by a novel continuous severe plastic deformation method

Commercially pure Al wires are severely plastic deformed by a novel method called equal channel angular torsion drawing (ECATD) up to four passes. Initial wires are drawn through an equal channel angular die and simultaneously torsion deformed by turning the ECATD die. The wires are deformed up to an equivalent strain of 1 to 4 (based on FE result) at room temperature. The microstructural evolution of the wires is investigated using optical microscopy of both longitudinal and transverse cross-sections. A grain refinement from 100 mm to a mean grain size of 1-10 mm is achieved mainly at the areas near the surface of the wires. A decreasing trend of grain refinement is observed from the edge area to the wire center due to the non-uniform strain distribution, resulting in an inhomogeneous hardness. A significant increase in hardness is obtained from ∗22 HV to ∗43 HV at the wire center and to ∗60 HV at the wire edge, this confirms simulated equivalent plastic strain. The most important advantage of this process is the ability to impose continuous large plastic deformation on wires. It can be used as an industrial method for continuous strain hardening and grain refinement of wires.