Microstructural evolution and mechanical behaviors of equal channel angular pressed copper

The mechanical properties including Vickers hardness, tensile properties, fracture toughness, impact toughness and also, the microstructure of copper severely deformed by equal channel angular pressing through route C after two, four, and eight passes at ambient temperature, were studied in the present work. The results indicated that the grains size reduced from 16.7 to 4.8 mu m after two and to 2.1 mu m after eight passes. This study cleared that because of the recrystallization phenomenon and reducing the effect of stress concentration and increasing the number of grain boundaries, the values of the fracture toughness can increase significantly. For example, fracture toughness increases by 58.4% relative to base metal after eight passes equal channel angular pressing. Also, it was found that the major improvement in tensile properties is achieved after two passes and due to the applied simple shear to the copper, all the equal channel angular pressed specimens have demonstrated an enhanced hardness and impact toughness, in accordance with their number of equal channel angular pressing passes. For example, the Vickers hardness is increased by a factor of 1.98 and impact toughness 58.4% for the extruded material after eight passes.