Formability and Microstructure of Dissimilar Aluminium Tailor-Welded Blanks (TWBs) Joined using Friction Stir and Gas Tungsten Arc Welding

Abstract In this study, to evaluate the performance of different welding techniques in joining dissimilar aluminum alloys, known as the Tailor Welded Blank (TWB) concept, and to investigate their resulting mechanical properties and microscopic structures, three aluminium alloys—AA3105, AA5052, and AA1200—were investigated. These alloys were joined as multi-material dissimilar blanks using Gas Tungsten Arc Welding (GTAW) and Friction Stir Welding (FSW). By conducting Nakazima formability tests on the welded specimens, forming limit diagrams (FLD) were extracted. The FLD indicated that, across the strain paths examined, the FSW joints generally showed higher forming-limit strains and a broader safe-forming region than the corresponding GTAW joints. FSW 1–5 displayed the greatest formability, while AA5052 exhibited the lowest overall forming ability. The improved formability of the FSW joints suggests the feasibility of solid-state welding for producing dissimilar aluminium sheets that will undergo subsequent forming operations. The FSW 1–5 joint exhibited approximately 152% higher displacement capacity than the corresponding TIG joint during Nakazima testing.