Wire electrode of 5754 aluminum modified by PVD-thin film depositions

Abstract

Manufacturers of welding wire electrodes for GMAW welding adapt the alloy compositions of welding wire electrodes in order to adjust the weld pool behavior and the properties of the weld. Additively manufactured components in various sizes and with complex structures and multi-axial stress states place diverse demands on the material. The filler wire can significantly influence the material properties. The approach shown here describes the possibility of coating welding wire electrodes by physical vapor deposition, which enables flexible adjustment of the welding material composition. The element content in the weld metal can be adjusted within certain limits via the coating thickness. In the arc, applied thin-film coatings with coating thicknesses < 1 µm pass into the molten phase together with the substrate wire electrode according to ISO 18273—S Al 5754 (AlMg3). Microalloying elements such as TiB2 or Ti added to the weld pool in this way change the composition and thus influence the microstructure in the weld metal. This results in a grain refinement of up to 46%, which in turn has a positive effect on hot cracking susceptibility. PVD-coated welding electrodes also show changes in arc characteristics. With increasing TiB2 layer thickness, the arc length decreases by up to 44%, while the arc current increases. The fusion penetration behavior changes from a narrow finger-shaped to a round fusion penetration.