Investigation on the formability of friction stir welded Al-TWB through incremental forming

Abstract

In the quest for weight reduction, automobile industries introduced the technology of tailor welded blanks (TWB) which offered utilization of material as per functional requirement. In general, friction stir welding (FSW) is mostly used for fabricating aluminum based TWBs as fusion welding of Al—alloys are problematic. Recently, single point incremental forming (SPIF) gained popularity among researchers as well as in industry as a dieless flexible forming technique. Hence, in this study two aluminum sheets namely AA6061 and AA7075 of similar thickness were welded together using FSW with square pin. The formability of the TWBs were evaluated in terms of cup height, wall angle and fracture location through SPIF incorporating different tool geometries. To assess the effect of weld, similar welded Al blanks were also deformed in the similar condition. The formability of the similar welded blanks and corresponding parent metals did not differ much and fracture did not initiate at the weld. However, cup depth for the TWB was in between the cup heights of the parent metals and failure was not observed at the weld region. TWB cups did not show any weldline shift.