EFFECTS OF SAMPLE DIRECTIONS ON DYNAMIC FORCED SHEAR DEFORMATION BEHAVIORS OF COLD-ROLL Cu SHEET

Abstract

The dynamic forced shear deformation behaviors of cold-rolled Cu sheet were investi- gated by means of Split-Hopkinson pressure bar technology. Hat-shaped specimens of cold-rolled Cu sheet, which were cut with the axes along the 0 ◦ (RD-0 ◦ ), 45 ◦ (RD-45 ◦ )a nd 90 ◦ (RD-90 ◦ ) directions from rolling direction lying in the rolling plane, were compressed with shear strain rate of 3.5×10 4 s −1 . The results show that the forced shear behaviors of cold-rolled Cu sheet for different directions exhibit pronounced anisotropy, both the yield strength and flow stress for the RD-90 ◦ direction sample are the maximum while those for the RD-0 ◦ direction are the minimum. The adiabatic shear deformation characteristics for different direction samples display much distinction. The adiabatic shear susceptibil- ity of RD-90 ◦ sample is the strongest while the RD-0 ◦ is the weakest. Based on the shear stress-shear strain curves and adiabatic shear dissipation energy, the difference of adiabatic shear susceptibility for different directions can be explained qualitatively. The ultrafine grains can be found within the shear bands for three different directions by electron backscatter diffraction (EBSD). The calculated results prove the possibility that the dynamic recrystallization can happen in shear bands based on the rotational dynamic recrystallization mechanism.