Extrusion limit diagrams containing structural and topological information for AA 6063 aluminium alloy

Abstract

The limits of extrusion can be high temperature flow stress related, surface related, or microstructure related. It is shown that the quantification of these features allows convenient representation within the extrusion limit diagram framework. This potential metallurgical process control is most important in the high strength structural alloys of the 2000, 5000, and 7000 series. It is the commonly extruded alloy, AA 6063, that has been considered in the work reported here. While mechanical properties remain an important consideration, the cosmetic appearance represents a special product requirement, particularly regarding the occurrence of the surface defects, pickup and die lines. It is shown, using experimental data from AA 6063 extrusion trials, that pressure requirements, microstructural features, and the surface defects, pickup and die lines, can be characterised through mathematical formulae and, therefore, represented within the limit diagram framework. Limit diagrams containing microstructural and topological information are presented.

MST/1626