Friction stir welding (FSW) is a solid state joining technique that has emerged as an efficient manufacturing technique for joining materials that can vary in composition and/or thickness to optimize weight or performance in the final component.  However, very little has been done on tailor welded blanks of aerospace aluminum alloys, i.e. 2xxx and 7xxx series. The published data is even scarcer when it comes to hydroforming of FSW tubes. The present study shows the preliminary results of the FSW of 2024-T3 tubes and the impact of the welding parameters on weld quality. The mechanical properties of the welds are assessed by hardness and tensile measurements on as-welded and heat treated tubes. For tensile testing, an automated deformation system, ARAMIS, is used to measure deformation at different regions of the weld, i.e. weld nugget, TMAZ and HAZ.

 It is found that:
i) By process optimization, the keyhole at the end of the weld is filled without material addition. The keyhole filling procedure is essential for hydroforming application.
ii) By process optimization, a defect-free weld, i.e. no excessive flashing, no lack-of penetration and no wormhole, is obtained. However, a systematic undercut defect appeared on the advancing side of the weld.
iii) In the tensile tested specimens, failure constantly occurred in  the weld nugget region. The total deformation measured in the tensile specimens was about %5. This low deformation value is mainly due to the undercut defect mentioned above. It is believed that the undercut behaves most probably as a local neck localizing the deformation right at the beginning of the tensile tests. Further investigation with the ARAMIS system revealed that local deformation in the weld region can reach %20, which is very close to the maximum deformation measured in the base metal.