Solidification Cracking Susceptibility of Welding Fillers Derived from Scrap Aluminum — Part 1: Powder Core Wire Experiments

Sustainable material production is becoming increasingly desirable for providing decreased energy consumption and emissions. The twitch aluminum scrap stream is high in elements such as Si, Fe, Cu, and Mg, which can pose challenges to reuse in existing alloys. Alternatively, it may be possible to use twitch to produce a novel wire feedstock for additive manufacturing and welding if compositions can be identified or engineered to resist solidification cracking. This study investigates the susceptibility of twitch-derived alloys to solidification cracking compared with commercially available alloys such as 6061, 4043, and 5356. Although predictions from solidification cracking criteria indicate that the twitch alloys should be more crack resistant than the commercial alloys, the results of Sigmajig weldability tests revealed that the twitch alloys were more crack resistant than 6061 but not 4043 or 5356. The lower-thanexpected weldability of the twitch alloys was attributed to oxides present in the welds, resulting from the powder core tubular wiremaking process used to produce these novel feedstocks. Despite lower weldability, welds from the twitch fillers exhibited considerably higher hardness than those of the other materials, indicating great potential to develop high-strength, weldable compositions from the aluminum scrap stream.