Defects at Interfaces in Co-Extruded Metals

Summary The strength of the interface between core and clad in hydrostatically co-extruded copper-clad aluminum has been measured as a function of the total extrusion ratio. It is found that the interface strength exhibits a minimum at a particular extrusion ratio. This phenomenon is investigated analytically by modeling the co-extrusion process using a finite element code, ABAQUS, to determine the stresses at the interface in the deforming region of the die and in the extruded product. These calculations show that the state of stress at this interface depends on the die geometry and on the extrusion ratio. The implications of this observation on the design of dies for co-extrusion are discussed.