Influência da oscilação magnética do arco elétrico na geometria de paredes multicamadas de passe único fabricadas por manufatura aditiva baseada na soldagem GTAW

Abstract

Parts manufactured by Wire Arc Additive Manufacturing have a poor surface finish and need to undergo machining operations before being put into service. In this step, the ideal is the amount of removed material to be as small as possible to avoid the waste of raw material. However, in thin-walled structures, this amount increases significantly because of the overflow of the weld pool. In this work, Magnetic Arc Oscillation was applied during the deposition of the weld beads for minimizing the problem. Thus, single-pass multi-layer walls of low carbon steel and Ti6Al4V were produced by the Gas Tungsten Arc Welding-based Wire and Arc Additive Manufacturing process with and without Magnetic Arc Oscillation, and the influence of this technique on the geometry and the process stability was evaluated. The geometric features were assessed using transverse section macrographs and the effects of different patterns and frequencies of oscillation on the arc characteristics, metal transfer and weld pool behaviour during the layer deposition were investigated using images and videos produced during the process. The results show that the wall becomes thinner, and the distribution of material along the wall length becomes more homogeneous when Magnetic Arc Oscillation is applied. An explanation of the effects of the technique on the wall geometry based on forces that act on the molten metal during layer deposition was made. Because of the swinging movement of the welding arc, the heat is distributed over a larger area, and the power density decreases. Thus, fewer previous layers are remelted, and the volume and the weight of the weld pool reduce. The distribution of arc pressure also becomes less concentrated, and the arc force on the molten metal decreases. Additionally, a magnetic force appears on the molten metal, which contributes to a change in the direction of the resultant force on the weld pool. Finally, Magnetic Arc Oscillation can minimize the overflow phenomenon and increase the deposition efficiency of the process.