Integrated design in welding and incremental forming: Mechanical behavior of friction stir welded blanks

The present study deals with the incremental forming of welded aluminium blanks. More specifically, blanks are initially welded by friction stir welding and the process parameters such as the rotational speed and the feed rate are changed to analyse and evaluate their influence on the mechanical properties of the blanks. Three main areas can be distinguished in the welded blanks, in addition to the base material: the nugget zone at the center of the weld, the thermo-mechanically affected zone and the heat affected zone. Tensile tests are carried out both on the base material and also on the welded material, transversely to the weld, using a digital image correlation device to capture the strain field. Several tests are performed to evaluate the influence of the welding process parameters on the mechanical properties of the blank. Then, the welded blanks are formed into conical structures by single point incremental forming, in order to assess their formability. Rupture occurs in the weld, highlighting the strong influence of the distribution of the mechanical properties resulting from friction stir welding on the formability.