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.

This paper reports the microstructure evolution, mechanical properties and strengthening mechanisms of a commercial purity Al alloy (Al 1350) after severe plastic deformation by a novel continuous method called ‘Equal Channel Angular Torsion Drawing (ECATD)’. Electron backscatter diffraction (EBSD) results revealed an inhomogeneous grain refinement including a large fraction of low-angle grain boundaries. After four passes, the microhardness increases from the initial value of 35 HV up to 44 and 62 HV at the centre and near to wire surface, respectively. A combination of high strength and ductility can be achieved based on the results of a Taguchi design of experiment (DoE) for mechanical properties. The strengthening occurs due to increment of the dislocation density, and development of mainly new low-angle grain boundaries.

No abstract

No abstract

No abstract