Preliminary Study on the Formability of a Laser-Welded Superplastic Aluminum Alloy

In this work, the effect of the laser-material interaction on the formability of a superplastic aluminum alloy was investigated. In applications such as Tailor-Welded Blanks and in the manufacturing of very large components with a complex shape, laser welding combined with superplastic forming may be a very fitting industrial tool. Bead on plate tests were carried out in order to simulate the laser-welding process and then, free inflation tests were performed to evaluate the compatibility of these two processing techniques. The Al-Mg alloy used in this work has a very small grain size which ensures the superplastic behavior. With the aim of preserving this peculiarity, the following aspects on the formability were investigated: (i) the surface condition of the bead before the forming test (with and without the removal of the excess of metal); (ii) the effect of the travel speed of the laser source on the mean grain size; (iii) the introduction of a refiner, commonly used in aluminum casts, in the molten pool in order to further reduce the mean grain size.