Influence of the Free Compression Stage on Magnetic Pulse Welding of Tubes

In magnetic pulse welding (MPW) of tubular parts, the acceleration of the ‘flyer’ part typically corresponds to a free electromagnetic compression (EMC) process over the distance of the initial standoff between the outer and inner tube. During this process stage, already significant plastic strains occur. In addition, wrinkling is a phenomenon frequently observed during EMC. In this manuscript, influencing factors on the wrinkling effect are identified, taking the initial geometry of the flyer tube and its manufacturing process into account. Moreover, a link between the strains and wrinkles caused by the tube compression and the MPW process is made. An experimental study is performed aiming for the quantification of the plastic deformation during EMC. The effect of this deformation on the stability and adhesion of brittle surface layers is analyzed. Accompanying numerical simulations help to understand the wrinkle formation and its influencing factors. Based on the results, hints for an improved process design of MPW are given.