Evolution of grain orientation and texture of copper and steel in copper cladding steel wires during drawing and annealing

Abstract

The microstructure, grain orientation and texture of copper and steel in copper cladding steel (CCS) wires during drawing and annealing were investigated by using EBSD. The results showed that the copper grains and ferrite grains of steel in CCS wires are elongated along the drawing direction and transformed to fiber microstructure. The microstructure of copper and steel in CCS wires experiences recovery, recrystallization and grain growth after annealing treatment. The elongated copper grains and ferrite grains of steel gradually transformed to equiaxed grains and the grain sizes increased with annealing temperature increasing. With the increase of deformation amounts, the misorientation angle of copper and steel changes from large angle to small angle and the texture variation of copper is not obvious, which is inconsistent with the texture change of pure copper wire. However, the texture variation of steel is consistent with that of a single steel wire, mainly the fiber texture in the direction of <110>. With the annealing temperatures increase, the misorientation angle of copper and steel changes from small angle to large angle. The variation of texture with annealing temperature is similar to that of single copper and steel wires. For copper, when annealing temperature is less than 850 °C, the intensity fluctuation of texture is not very obvious. The <111>-<211> texture becomes diffused. However, when annealing temperature is more than 850 °C, the texture included a number of strong <111> annealing texture and a few of weak <110> annealing texture. For steel core, the <110> fiber texture doesn’t disappear and only the fiber texture transforms to the annealing texture. The intensity of texture increases slightly with increase of annealing temperature.