Change in the Microstructure of Copper Wire After Twisting in an Equal-channel Step Matrix and Drawing

The influence of a new technology of copper wire processing on the change of its microstructure is investigated. This technology consists in deforming the wire in a rotating equal-channel step matrix and subsequent drawing. The matrix rotates around the axis of the wire and thereby creates stress due to equal-channel angular pulling and twisting in the matrix. The deformation was carried out at room temperature. The results of the laboratory experiment show that the application of such a combined technology allows to obtain wire with gradient structure. The surface layer is milled to 500 nm to a depth of ≈ 1 mm. Further, the grain size increases towards the central part of the wire and is 4 μm. The share of large-angle boundaries in the surface layer of the deformed wire is 68%, in the middle layer ≈ 42% and in the center ≈ 25%.