Effect of cold drawing deformation on the microstructure and properties of pure copper

Wires with different deformations were obtained by multipass cold drawing of a pure copper bar by an industrial wire drawing machine. The annealing experiments were carried out at 400 ℃ for 1 h to study the effects of microstructure changes on the mechanical and electrical properties of wires with different deformations. When the deformation of the samples increased from 0 to 60%, the grain size in the drawing direction (DD) decreased from 101.3 μm to 17.6 μm, the grain size in the transverse direction (TD) decreased from 103.4 μm to 16.4 μm, and the grain size was equiaxed. When the deformation amount increased to 90%, the grain size in the drawing direction was 14.1 μm, and the grain size in the section direction was 7.6 μm. The specimen microstructure consisted of deformed grains and equiaxed grains. When the deformation increased from 0 to 90%, the tensile strength increased from 221.5 MPa to 271.5 MPa. When the deformation was 60%, the tensile strength was 244.9 MPa, the elongation reached the highest value of 51%, and the electrical conductivity was 99.4% IACS. The orientation ratio of < 111 > + < 100 > in the samples was inversely proportional to the elongation of the samples. The in situ tensile observation showed that the crack propagation path was more tortuous in the process of cracks crossing the grain boundary for annealed samples. For the drawn samples, crack initiation occurred in the deformed grain, and the crack propagation path was relatively straight.