Comparative Characterization through Torsion Tests of Primary and Secondary Aluminum Alloys for the Extrusion Process

In the transition to a circular economy in the automotive sector, it is essential to integrate recycled (or secondary) aluminum alloys into extrusion processes, while ensuring that their performance is as close as possible to that of primary alloys. Within the Horizon Europe ZEvRA project, this study aims to analyze and investigate the hot deformation behavior of four aluminum alloys: two AA6082 alloys (primary and recycled) to directly assess their suitability for alternative use from a sustainability perspective, and two widely used automotive alloys, recycled AA6061 and primary AA7108, to provide reference data for industrial applications. Hot torsion tests were conducted under temperature and strain rate conditions representative of industrial extrusion processes. Four different temperatures (400, 450, 500, and 550 °C) and four different strain rates (0.01, 0.1, 1, and 10 s⁻¹) were investigated, allowing the achievement of significantly higher strain levels compared to conventional standard tensile and compression tests. Subsequently, the flow stress curves obtained from the torsion tests were analyzed to evaluate the influence of temperature and strain rate on the plastic deformation behavior of the material and on the associated dynamic softening mechanisms. The results demonstrate a comparable deformation behavior between primary and secondary alloys, confirming the feasibility and full compatibility of recycled alloys for highperformance industrial extrusion applications. Furthermore, experimental results provide a solid basis for the development of robust constitutive models to support FEM simulations aimed at optimizing metal forming processes within a circular manufacturing framework.