Abstract:
Experiments were carried out to determine the effect of the increase in the positive polarity current on cathodic cleaning, arc voltage, arc power and weld bead geometry on AC-TIG welding of aluminum, whereas the positive and negative polarity times were kept equal and constant. For each positive current tested, the current during the negative half-cycles was adjusted, so that the RMS current remained constant. Regarding the weld bead geometry, the results differ from those commonly reported in the literature, which suggest that the current during positive polarity has a minor role in the melting of aluminum, being only effective for the removal of oxides. Despite the decrease in the negative current values, the increase in the positive current caused an increase in substrate fusion. The positive current was found to have less influence on cathodic cleaning if compared to the positive polarity time.
Keywords: AC-GTAW, aluminum welding, variable polarity, cathodic cleaning, thermionic emission, field emission
Referência:
DUTRA, J. Carlos; CIRINO, L. Machado; GONÇALVES E SILVA, R. Henrique. AC-TIG Welding of Aluminium - New Perspective for the Evaluation of the Role of the Positive Polarity Current. Welding and Cutting, Volume 9, Number 5, October 2010 , pp. 320-325(5)