Co-extrusion of metallic materials is a potential method to produce composite products for the automotive, aerospace and nuclear industry. This can be accomplished by extruding a billet which is composed of an inner core embedded in a sleeve of a different material. Due to the different flow properties of the materials and the interaction between the mechanical and thermal fields, the co-extrusion process may result in fracture and non-uniform core dimensions. In this study, co-extrusion of a composite Al-Mg billet was investigated. The billet was composed of a magnesium rod embedded in an aluminum tube. Unlike conventional co-extrusion methods, the setup used in this study is not designed to reduce the core cross section during the extrusion process, thus the magnesium rod acts as kind of a "floating" mandrel. Prior to extrusion, the aluminum tube was heated to the extrusion temperature while the magnesium rod was kept at room temperature. The composite billet was assembled seconds before the extrusion. The effect of several extrusion parameters, such as temperature, die angle and extrusion ratio, was investigated. The geometry of the magnesium imaging. Metallography was used to obtain microstructure of the interface and investigate the relation between extrusion temperature and interface interaction. A verified and validated finite element simulation was performed for getting a better understanding of the plastic flow during the co-extrusion process. The results of this study demonstrate that uniform dimensions without fracture can be obtained by controlling the process parameters.
