A novel sustainable recycling approach leveraging circular economy for in situ processing of AA 6063-T6 chips into bimetallic tubular components via the FSBE process

Conventional recycling through remelting is an energy-intensive route and causes permanent material loss. In contrast, solid-state techniques like friction stir consolidation (FSC) and friction stir backward extrusion (FSBE) have emerged as energy-efficient, sustainable alternatives for metal scrap recycling. While prior studies have primarily focused on consolidation, or extrusion of bulk material, this study introduces a product-centric approach for the direct fabrication of bimetallic tubular components from AA-6063 T6 chips. This approach involves FSC followed by FSBE within the same die using two different tools, resulting in the recycling of chips in the form of bimetallic tube fabrication. The bonding efficacy of the fabricated product was evaluated through push-out tests and flattening tests. This approach enables adequate frictional heat and plastic deformation, resulting in continuous intermetallic compound layer formation at the interface. The residual voids after each step were analyzed through X-ray computed tomography (XCT) scans. The void fraction was reduced to zero after extrusion from the void fraction of ∼0.21% following the second compaction. This approach demonstrates a scalable, energy-efficient pathway for recycling metal chips into bimetallic tubular components, highlighting its potential for sustainable and material-efficient manufacturing, aligning with industrial needs.