Effects of macro and microstructure of aluminum alloy AA 6063-T6 with TIG-AC welding process with unbalanced rectangular wave

Abstract

The use of the rectangular wave in the TIG-CA welding process for aluminum alloys allows numerous possibilities of frequency control, wave amplitude variation and positive or negative current for the same wave cycle. The configuration selected is decisive for the effect and final property of the weld bead, where alternating current variation in aluminum alloy welding is widely used and is intended to promote surface oxide layer cleanliness while promoting penetration of the joint. In the literature it is common to find statements that the cleaning of the oxide layer at the welding time is connected to the positive wave cycle and the penetration is connected to the negative wave cycle time. For the research proposal, TIG-AC welding of the aluminum alloy AA 6063-T6 was performed by simple plate deposition with rectangular wave with variation both in the current and in the time of positive polarity of the electrode in the cycle in the current welding wave 140 A, For balance conditions at 50% of the positive polarity at a waveform time period of 20 ms, followed by wave unbalance to 32.5% and 15% of the positive polarity acting time maintaining a constant frequency of 50 Hz for all settings. The results for the selected settings show that the decrease in the positive wave time decreases the penetration and the width of the weld bead and this may be related to the selection of time and frequency used.