Grain Refinement Mechanism and Texture Evolution of Polycrystalline Cu Sheets during the Electromagnetic Forming Process

The grain refinement mechanism and texture evolution of electromagnetically formed polycrystalline Cu sheets were investigated using the electron back-scattered diffraction(EBSD) technique. It is found that the average grain size decreases from 35.88 μm to 8.77 μm. The grain refinement was mainly attributed to dynamic recrystallization(DRX) at the grain boundary regions of bulged Cu samples where the inhomogeneous dislocation density and the large lattice misorientation were observed. The DRX mechanisms at the grain boundaries were discussed with respect to the strain-induced grain boundary migration nucleation. Moreover, the orientation distribution function(ODF) of the sample with the strain of 50% demonstrated a strong {110}<211> texture and a relatively weak {001}<100> texture. The texture evolution was discussed using the plastic work values of the grains with various orientations, which were calculated according to the Taylor model and the virtual work principle. The experimental results show that the expended plastic work of the grains with {110} orientation is 9.69 MPa, which is distinctly higher than those of the grains with the {001} and {111} orientations. This indicates that the formation of the {110} orientated texture would be preferred with increasing strain in good agreement with the experimental result.