Cu-Zn-Si alloy bars were caliber rolled using three different groove shapes of conventional rhombus, flattened hexagon, and combination of oval and circle. In all the rolled bars, heterogeneous nanostructure comprising mechanical twins and shear bands was uniformly developed. The hardness increased with increasing reduction. Among the groove shapes, the combination of grooves of oval and circle produced the most homogeneous hardness distribution. Up to reduction of 70%, the combination of grooves of oval and circle derived also highest tensile properties of 801 MPa tensile strength and 11% ductility. Nevertheless, these differences in the mechanical properties attained by using three groove shapes became gradually smaller with increasing reduction over 70%. The finite element calculation, which simulated change in the plastic strain distribution during caliber rolling, revealed that the combination of oval and circular grooves produced the most homogeneous distribution of plastic strain with the highest average. These simulation results were consistent with the experimentally observed microstructural evolution and enhancements of mechanical properties.
Miura et al. (Thu,) studied this question.