Extrusion of hybrid sheet metals

This study focused on the extrusion of hybrid sheet metals. Co-extrusion of profiles having sheet metals as reinforcing elements are a promising alternative to the more common rotation-symmetric composite rods or wire reinforced profiles. The influence of non-rotation-symmetric die geometry was investigated by extruding aluminum alloy billets with three different types of sheet metals as core material and the aluminum alloy (AlMgSi1 EN AW-6082) as sleeve material. The hybrid sheet metals were analyzed by non-destructive testing using ultrasonic testing and X-ray inspection. The steel (DC 06) and the titanium (titanium grade 1) cores fractured during extrusion, while the magnesium alloy core (AZ31) showed a uniform deformation. A new deformation mode in co-extrusion has been found for the titanium grade 1 core which most likely fractured due to a combination of tensile and shear stresses caused by the material flow of the non-symmetrical cross-section of the profile. The DC 06 core predominantly fractured due to tensile stresses. Microstructural analysis showed a decrease in thickness for all cores, with AZ31 showing the highest reduction and DC 06 the lowest. It was found that no intermetallic phases occurred having a DC 06 or titanium grade 1 core. However, EDX line scans indicated the start of diffusion processes at the interphase of EN AW-6082 and DC 06. An intermetallic phase could be observed for the specimens having an AZ31 core, EDX line scans showed this to be the Al3Mg2 (β) phase.