| Abstract Scope |
Sustainable material production is becoming increasingly necessary to decrease energy consumption and reduce emissions. Aluminum production from ores accounts for 3% of global industrial emissions, therefore finding opportunities to increase scrap utilization can be beneficial. The twitch scrap stream consists of primarily wrought and automotive Al scrap which has been heavily recycled, accumulating several elemental additions like Si, Fe, Cu, and Mg which reduce the recyclability with each successive recycling step. There is opportunity to produce high-strength, weldable alloys from the twitch stream. However, one of the major challenges many high strength age-hardenable Al alloys is solidification cracking. In this talk, we show how tailoring Cu content in the twitch system through modeling and experiments can yield excellent solidification cracking resistance while optimizing the age hardening response. The solidification cracking resistance and aging response was determined for three different twitch-based compositions, one with 0.3 wt% Cu, 0.9 wt% Cu, and 2.2 wt% Cu, to demonstrate weldability and age hardening as a function of composition. Additionally, we will discuss the tensile behavior of each of these alloys as base materials to highlight the versatility of the twitch alloys. Finally, we will discuss how the twitch alloys compare to commercial weldable alloys like 4043 and 5356, and commercial age hardened alloys like 2024, 7075, and 6061. Overall, this work shows that alloy design, with sustainability as a boundary condition, can be implemented to produce useable compositions from the Al scrap stream. |