Anisotropy in mechanical properties of high-purity copper processed by equal channel angular extrusion

High-purity oxygen-free electronic copper has been processed by equal channel angular extrusion for up to four passes at room temperature, using 90° tooling, by either route Bc or C. Small tensile specimens and compression cubes were sectioned by electro-discharge machining and tested in the as-processed condition. The equal channel angular extrusion (ECAE)-processed material was mechanically anisotropic, with the strength in compression in the direction perpendicular to the plane formed by the inlet and outlet channels being greater than that in the other directions, for both routes. Work softening occurred after a strain of about 1% in this direction, whereas slight but positive work hardening occurred in the other directions, for both routes. In the extrusion direction, the strength in compression was greater than the strength in tension, for both routes. Modeling which assumes that active slip planes harden more rapidly than inactive planes can predict the measured behavior reasonably well, apart from the work softening.