Effect of Rotary Forging on Microstructure Evolution and Mechanical Properties of Aluminum Alloy/Copper Bimetallic Material

The influence of a degree of strain by rotary forging, as well as post-deformation annealing on the structure and mechanical properties of a clad aluminum alloy/copper bimetallic material was studied. Rotary forging of the initial bimetallic billet was carried out step by step from a diameter of 20.1 mm to a diameter of 2.4 mm. Rotary forging of the aluminum alloy/copper bimetallic material to a diameter of 5.3 mm leads to the formation of a mixed fine-grained and nanocrystalline oriented structure in an aluminum shell and to a decrease in the average grain size by 4.5 times and to an increase in the density of crystalline defects in a copper core. A reduction in the aluminum alloy/copper bimetallic material diameter to 2.4 mm (with intermediate annealing) leads to the formation of a fine-grained elongated grain-subgrain oriented structure in the aluminum shell and to the formation of a mixed cellular and subgrain structure in a copper core. Rotary forging leads to a significant increase in the strength of the aluminum alloy/copper bimetallic material and to a decrease in ductility. The optimal combination of increased strength and satisfactory ductility provides post-deformation annealing.