The effect of surface shape on the production of aluminum-copper two layer tubes using forward extusion process

The use of bimetal tubes due to the improvement of its mechanical and physical properties compared to single layer tubes has been considered by various industries. These tubes are produced in a variety of processes, but because of the compressive stress in the extrusion process, this process is more suitable for making rods and tubes which increases the possibility of forming metallurgical bands between the two metals. In this study, the effect of the tube surface shape on the production of bimetal tubes in both copper shell and aluminum core and vice versa has been investigated through extrusion process. In order to achieve the proper mechanical connection and optimum connection quality, the tubes were prepared in three different surface shapes. In this way, grooves between the bimetal tubes were created to form the layers and were filled by the process of extrusion of the empty space of the layers. Finally, extrusion process of bimetal tubes was carried out in two extrusion ratio of 40 and 60 percent. In order to investigate the mechanical properties, the crushing test was performed on the produced bimetal tubes. Microscopic images in both copper shell and aluminum core and vice versa showed that the formation of the groove in each two-layers, causes the proper mixing between the two tube layers. Also, the results of the crushing test showed that the tubes with both grooves had better resistance than the other ones.