Numerical investigation of the surface recrystallization during the extrusion of a AA6082 aluminum alloy under different process conditions

The microstructure of 6xxx aluminum alloys deeply affects mechanical, crash, corrosion and aesthetic properties of extruded profiles. Companies, especially in the transportation sector, require control over the grain structure in order to ensure the quality and the performance of the products. A main challenge for the extrusion companies is to accurately predict the profile microstructure at the design stage, trying to limit the formation of coarse grains and, consequently, the reduction of the mechanical properties of the component. In this work, the modeling of the stored energy, driving force for the recrystallization, was carried out and implemented within the Qform Extrusion FEM code. A novel approach for the evaluation of fibrous and recrystallized microstructures in 6XXX aluminum alloy profiles was proposed and tested in a campaign of experiments involving the extrusion of AA6082 round bars under several die designs and processing conditions. The outcomes proved the good accuracy of the recrystallization predictions during the extrusion of AA6082 aluminum alloy.