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

Abstract

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 μm to a mean grain size of 1–10 μm 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.

Strengthening mechanisms of Al wires processed by equal channel angular torsion drawing

“…Although there are small plastic strains due to tensile stress components and cross-section reduction, it has been shown that those terms can be calculated assuming the constancy of volume [17]. Several researchers have investigated the influence of inner radius (r) on different parameters of the ECA process [63][64][65].…”

“… where is the equivalent strain after N passes of the deformation, is the angle of intersection of the two channels, is the angle subtended by the arc of curvature at the intersection, is the equivalent strain due to torsion, is the radial position, is the number of rotations and is the gauge length of wire. Although there are small plastic strains due to tensile stress components and cross-section reduction, it has been shown that those terms can be calculated assuming the constancy of volume [17]. Several researchers have investigated the influence of inner radius ( r ) on different parameters of the ECA process [63-65].…”

“…Among all the developed methods, continuous processes have attracted more attentions such as equal channel angular rolling (ECAR) [9], Conshearing [10], ECAP-Conform [11] and most recently single roll angular rolling (SRAR) [12]. There are also some other continuous SPD methods which use drawing instead of pressing of a raw materials in form of sheets, rods or wires such as equal channel angular drawing (ECAD) [2,13,14], continuous shear drawing [15,16], equal channel angular torsion drawing (ECATD) [17] and combining drawing with shear [18]. Such processes are able to produce long length SPD-ed products in the form of strips, rods and wires, which shows their potential to adapt to the existing manufacturing environments.…”

“…Recently, a novel continuous SPD method called Equal Channel Angular Torsion Drawing (ECATD) has been developed to enhance the mechanical properties of wires [17]. This technique enables the fabrication of fine-grain wires without limitation in length up to several metres.…”

Equal channel angular pressing of wire-formed Al6063 by PU rubber-assisted procedure

“…Also, some obstacles are predicted for its industrial applications. Pourbashiri et al 32 introduced a new method both in a numerically and experimentally way, entitled equal channel angular torsion drawing in order to produce strain-hardened wires. In this regard, an initial wire sample is deformed with an equal channel angular section and simultaneously, torsional drawn by turning the die.…”