Uncovering Technological and Environmental Potentials of Aluminum Alloy Scraps Recycling Through Friction Stir Consolidation

Conventional metal chips recycling processes are energy-intensive with low efficiency and permanent material losses during re-melting. Solid state recycling allows direct recycling of metal scraps into semi-finished products. It is expected that this process category would lower the environmental performance of metals recycling. Friction Stir Consolidation is a new solid-state technique taking advantage of friction heat generation and severe plastic deformation to consolidate chips into billets. In this research, the feasibility of Friction Stir Consolidation as aluminum chips recycling process is analyzed. Specifically, an experimental campaign has been carried out with varying main process parameters. Three main aspects have been evaluated in order to highlight products quality and environmental impact of the process: (i) metallurgical and mechanical properties of the consolidated products; (ii) primary energy demand, as compared to conventional processes; (iii) forgeability of the consolidated products, as compared to parent material. Results revealed that a proper process parameters selection results in fully consolidated aluminum disk with satisfactory mechanical properties. Also, the new recycling strategy allows substantial energy savings with respect the conventional (remelting based) route.