Formability of similar and dissimilar friction stir welded AA 5182-H111 and AA 6016-T4 tailored blanks

The formability of similar and dissimilar tailor welded blanks (TWBs), obtained by friction stir welding of 1 mm thick plates of AA 5182-H111 and AA 6016-T4 aluminium alloys, was analysed by deep drawing cylindrical cups. The metallurgical and mechanical characterization in tension of the welds was already published elsewhere [Leitao C, Leal RM, Rodrigues DM, Loureiro A, Vilaça P. Tensile behaviour of similar and dissimilar AA5182-H111 and AA6016-T4 thin friction stir welds. Mater Design 2009;30:101–8]. In order to understand the formability behaviour of the TWBs, the base materials anisotropy was studied by performing tensile tests at several angles with the rolling direction. Two different types of round TWBs, with 180 and 200 mm diameter, were used in the deep drawing tests. From current study it was possible to conclude that the formability of the TWBs is strongly influenced by the type of mismatch in mechanical properties, between the welds and the base materials, and also, by the initial size of the blanks. Rupture of the cups only occurred under the presence of weld defects, which confirms the good plastic behaviour of the friction stir welds both in overmatch and undermatch conditions.