Effects of Cold Rolling Path on Recrystallization Behavior and Mechanical Properties of Pure Copper During Annealing

Abstract

This study investigated the recrystallization behavior, grain boundary characteristics and distributions, and mechanical properties of pure Cu foils subjected to cold rolling parallel (RD), perpendicular (PD), or both parallel and perpendicular (CR) to the original rolling direction, followed by annealing at 400 °C for 10, 30, 60, and 420 min. The recrystallization behaviors and microstructural evolutions of the specimens were characterized using optical microscopy and electron backscatter diffraction, and tensile tests were performed at room temperature to determine mechanical properties. The unannealed specimens exhibited prominent {100} <100> cubic and {011} <100> Goss textures that underwent recrystallization through oriented growth to form random textures in the RD, TD, and CR specimens after annealing for 10, 60, and 420 min, respectively. The CR specimen annealed for 60 min exhibited the smallest grain size of 3.2 μm; the average grain sizes of the RD, TD, and CR specimens annealed for 420 min were 8.7, 12.0, and 10.8 μm, respectively, corresponding to low-Σ coincident site lattice grain boundary fractions of 58.7%, 56.4% and 56.3%, respectively. The migration rates of the recrystallized grain boundaries with different orientations differed during annealing according to the applied rolling path. In terms of a practical production, cold-rolled pure Cu exhibits suitable mechanical properties after annealing at 400 °C for 60 min regardless of applied rolling path.  These results could be expected to provide guidance for tuning microstructure and properties of pure Cu foils and designing of fabrication routes for pure Cu foils, such as rolling and drawing.

Keywords: Rolling paths, Recrystallization behaviors, Grain boundary character distribution, Mechanical properties, Copper