Process-Related Characterization of the Influence of the Die Design on the Microstructure and the Mechanical Properties of Profiles Made from Directly Recycled Hot Extruded EN AW-6060 Aluminum Chips

Solid-state-recyclingSolid-state-recycling processes for aluminum chipsAluminum chips are promising alternatives to energy-intensive re-melting. In order to directly recycle aluminum chipsAluminum chips without the necessity of re-melting, these are pre-compacted and further processed into profiles in a hot extrusionHot extrusion process. The quality of the so-produced profiles depends on the quality of the interface between the single chips, which are linked by microstructural welding. In order to enable a successful welding process, the pathways during the extrusion process have to be long enough in order to transfer enough energy and the encasing oxide layers have to be broken up successfully. Parameters like pressure, shear strain, and temperature influence the quality of the oxide layer breakup. Especially the shear strain can be varied by the material flow and the die. Therefore, this study examines the effects of different extrusion dies on the microstructure and the mechanical properties. The microstructure was characterized using metallographic investigations and could found to form within four different zones depending on the conditions during the extrusion process. The mechanical properties were investigated by means of tensile tests and fatigue testsFatigue tests and could be correlated well with the microstructure, since two different damage mechanisms depending on the specimen position can be distinguished.