Characterization of microstructure evolution after severe plastic deformation of pure copper with continuous columnar crystals

Pure copper bar with continuous columnar crystals was fabricated by continuous unidirectional solidification. The bar with orientation preference along [0 0 1] exhibited novel plastic deformation ability with total true strain over 13.5 during rolling and drawing at room temperature without annealing. Microstructure analysis and in situ observation of tensile test were performed to investigate the mechanism of plastic deformation. Results exhibit that the novel plastic deformation ability of copper bar is beneficial from the absence of transverse grain boundary as well as small angle grain boundary of the continuous columnar microstructure. The existence of cell structure, recrystallization and deformation twin leads to grain rotation during deformation and enhances the orientation preference of the continuous columnar crystals, enabling copper bar a high ability for further deformation.