Hot Extrusion of High-Strength Aluminum Alloys with Rotary Porthole Dies

High-strength aluminum alloys due to their light-weight and high-strength are widely used in applications in the automobile, aerospace, and other industries. However, their low extrudability, even under hot extrusion conditions, restricts part producibility necessitating improvements in both alloy extrudability and the extrusion process itself. Extrudability is influenced by microstructure and the die-material friction conditions. Understanding the interrelation between alloy properties and its in-process microstructure change is a critical key to advance the hot extrusion process of these alloys. To enhance the extrudability of these and similar difficult-to-extrude materials, the research objective of this proposal is to accelerate the hot extrusion rate and control the high-strength alloy’s microstructure by a newly conceived extrusion process with a rotary porthole die. The physical phenomena within the die will be investigated in terms of metal flow, in-process microstructure change as well as temperature and load profiles. Additionally, the die-alloy interfacial friction mechanisms will be studied. With the understanding of these mechanisms, a rotary porthole die testbed will be designed and built for process feasibility and performance assessment and model validation. The fundamental advances made will also be applicable to other difficult-to-extrude alloys.