Effect of Low-Temperature Annealing on the Bending Properties of C19400 Copper Alloy Strips

As connectors become miniaturized, higher requirements are put forward for the bending performance of the materials used. In this paper, the effect of a low-temperature annealing process on the microstructure and properties of a C19400 copper alloy strip were studied. The surface morphology of the strip after bending was observed by scanning electron microscopy (SEM). Electron backscattering diffraction (EBSD) was used to analyze the microstructure change. The results showed that the springback decreases with increasing annealing time. When the relative bending radius is 0.4, a large number of cracks appear on the cold-rolled surface, and no cracks appear on the surface of the alloy after annealing for 60 min. For microstructure analysis, when annealing for 60 min, the grain structure is fine, the deformation is distributed in each grain during bending, and the grains involved in deformation increase to avoid stress concentration. The strength of the goss texture was increased and that of the brass texture was decreased, which effectively avoided strain localization. The decrease in grain size and the increase in favorable texture strength are the main reasons for the improvement in bending performance. With the increase in the recrystallized structure, the strip shows a decrease in strength and an increase in plasticity.