INFLUENCE OF SHIELDING GASES ON THE WAAM PROCESS FOR ALUMINIUM IN REDUCING DEFECTS AND INCREASING PROCESS EFFICIENCY

WAAM (Wire Arc Additive Manufacturing) technology is a manufacturing technique based on combining metallic wire with arc welding techniques to melt it and generate, layer by layer, the geometry of the final part. This additive manufacturing (AM) process is offering a new manufacturing perspective to the industry, as it allows higher deposition rates than other additive manufacturing techniques despite having lower dimensional accuracy in its raw state. This study analysed the influence of shielding gases on defect reduction and process efficiency improvement. To this end, thin-walled test pieces were welded using pure argon, Perfect 1 (argon + O2 + N2O) and H30 (70% argon + 30% helium). Computed tomography and macrographs were used to analyse defects. The results obtained show a decrease in the level of defects and porosity when adding helium to the argon shielding gas, also reducing the intensity and voltage of welding, which translates into lower thermal input, helping to prevent the molten bath from spreading before solidification, so that the ratio between width and height tends to be lower. The addition of O2 and N2O to the argon shielding gas does not mitigate porosity or internal deffects, nor does it enable a reduction in the welding parameters. However, the wall welded layer by layer with this gas mixture exhibits improved uniformity and homogeneity, with reduced necking in the initial layers.