Superplastic forming of 5083 aluminum alloy sheet joined using friction stir welding

Abstract

To develop a new SPF process using tailored blank technique, a series of forming experiments were carried out on 5083 SPF grade aluminum alloy sheets. Some rectangular blank sheets, with a butt joined line at each longitudinal center, were prepared using friction stir welding (FSW) under several conditions. The blank sheets were experimented to form into a slender pan with rectangular section, for intended reduction of thickness about in half, provided the forming is successful. Some blank sheets were formed successfully with decreased thickness on the joined line relative to the reduction on the base metal. Few defects or cavitations were observed in magnified views of cut section sampled from the joined line of the pan formed successfully. And it was found that the mechanical properties in that joined line kept the level of before forming. It means that a kind of superplastic deformation is happened in the joined line, if the conditions of FSW are suitable for SPF. As a result, the relationship between the superplastic formability in the joined line and the conditions of FSW was analyzed, and the possibility in the realization of the new process was verified.