Experimental investigation of direct co-extrusion for bimetallic tubes

Abstract. The current study aims to investigate the parallel direct extrusion of bimetallic tubes with a variable thickness ratio of the tubular layers. The bimetallic specimens consist of an aluminum tube as the inner layer and a copper one as the outer layer. Initially, quasi-static compressive tests are performed for the two utilized materials to estimate the fundamental material compressive properties. Following, the extrusion experiments are conducted and the load-displacement curves and the morphology of the final bitubes are examined. Also, the sliding of each tubular layer is evaluated by measuring their length. Finally, greater thickness in the outer pure-Cu tube reveals higher peak force and later material exit from the die, while the extrusion load depends proportionally on the total thickness. The aluminum inner tubes showed greater elongation than the outer copper ones, while reduced sliding was observed in the case of increased extrusion load due to the implementation of co-extruded bonding between the two layers.