Transition from earth mining toward urban mining: up-cycling post-consumer scraps to produce automotive grade aluminum extrusions

Abstract

Aluminum extrusions encompass a range of structural components for managing crash energy. Currently automotive grade aluminum extrusions are made from primary aluminum of high carbon footprint. This study proposes a pathway to significantly reduce carbon footprint of automotive grade aluminum extrusions via using post-consumer scrap. Guided by thermodynamics-based simulations, 0.25 wt% was set as the iron tolerance limit for aluminum AA6082 alloy extrusion. This enables a scrap utilization ratio exceeding 70% in casting, which has been demonstrated in a production trial. Extrusions made from the low-carbon AA6082 alloy has a yield strength of 316.3 ± 3.5 MPa, an ultimate tensile strength of 343.9 ± 1.9 MPa, and a tensile elongation of 13.4 ± 1.2%, all of which are comparable to those of the commercial AA6082 extrusion made from 100% primary aluminum. Component-level 3-point bending test shows that front bumper beams made from low-carbon and commercial AA6082 alloys have the same performance. These results indicate that up-cycling post-consumer aluminum scrap to produce automotive grade extrusions is a promising route to help decarbonize vehicle manufacturing process.