Effect of trace additions of Scandium on plastic instabilities during forming of Al-Mg automotive alloys

Aluminum-magnesium 5xxx series alloys (e.g., 5182, 5052) are used to fabricate interior structures for automotive body-in-white components including door and hood panels. These alloys are typically not used on vehicle exteriors due to surface imperfections that develop during forming operations. The surface defects, which result from plastic instabilities, including Lüders bands and Portevin-Le Chatelier (PLC) effect, are associated with interactions between dislocations and magnesium solute atoms during deformation. The susceptibility to plastic instabilities in these alloys is controlled by factors including, alloy composition (Mg concentration), processing history of the sheet product, and deformation conditions (stain rate, temperature and loading mode). This presentation will discuss the effects of trace additions of scandium on plastic instabilities in a modified Al-Mg 5xxx series type alloy. Specifically focusing on cost tradeoffs between increased performance/improved manufacturability and cost associated with adding scandium.