Unified casting (UniCast) aluminum alloy—a sustainable and low-carbon materials solution for vehicle lightweighting

Casting aluminum (Al) alloys have been widely used in the automotive industry to improve fuel economy as well as to reduce greenhouse gas (GHG) emissions in the vehicle use phase. However, the casting Al alloys used for load-bearing body and chassis components today are mostly made from primary Al with a low impurity Fe content typically less than 0.2 wt.%, owing to the requirements for high ductility and adequate fatigue strength. Primary Al is made directly from alumina which was refined from aluminum ore (bauxite), using an electrolytic process which consumes a lot of energy and produces GHG emissions that are much higher than those from steel making. The objective of this paper is to present a Unified Casting (UniCast) Al alloy concept as a sustainable materials solution for vehicle lightweighting. The UniCast alloy chemistry is intentionally designed to be more tolerant of Fe impurity. This chemistry can not only satisfy the requirements on castability, but also deliver mechanical properties needed for a variety of thin-walled and thick-walled automotive structural components that are produced by various casting processes. The UniCast alloy concept will contribute to the establishment of a closed-loop recycling system in the future as the shredded scrap obtained from the disposed end-of-life vehicles can be directly recycled back into UniCast alloy ingot with a more efficient sorting process. In addition, by setting the upper limit of Fe content in the UniCast alloy to a higher level, it will become possible to use a high fraction of post-consumer scraps to produce this alloy. To demonstrate the feasibility of this concept, an exemplary UniCast alloy chemistry has been elaborated in this article. Furthermore, challenges and future research opportunities related to the realization of UniCast alloy concept in the automotive industry are discussed. It is hoped that this article will be of great implication to industrial researchers and academicians for making concerted efforts to establish closed-loop recycling of Al castings for the automotive and other transportation industry segments.