Influence of the Boundary Layer in Magnetic Pulse Sheet Welds of Aluminium to Steel

Abstract

In this paper, influential factors on the bonding strength of magnetic pulse welds between Aluminium (A1050) and Steel (S235JR) sheets are shown. First, a process window defined by varying charging energy and standoff distance for the welds. These welds will be characterised by the means of weld length and shear strength. Sound parameters are worked out at a standoff of 1.5 mm and a charging energy of 9 kJ. Nevertheless, no direct correlation between archived weld length and weld strength can be seen for the specific parameter set with a glass blasted, nearly polished surface. The achievable shear strength for this parameter set varies in the magnitude of 30 %. The chosen parameters are used to investigate the effect of surface preparation on the weld. Surface preparation has an acceptable impact on the achievable weld length in the interface and on the maximum shear strength. Furthermore, a controlled surface appearance reduces the statistic deviation of the weld length. It is shown that machining, which cuts grooves perpendicular to the collision direction, enhances the joint performance as well as the achievable weld characteristics. Furthermore, an acceptable impact of the rolling direction of the steel on the appearance of the joint interface will be shown. A rolling direction which lies perpendicular to the collision direction enhances the bulging of the steel into the aluminium.