Alternating Current TIG Welding
AC TIG welding uses periodic polarity reversal to remove the oxide layer from aluminum while reducing thermal stress on the tungsten electrode.
Physicochemical mechanism of action
TIG welding with alternating current uses a periodic polarity reversal between cathode and anode. This causes the cleaning cathodic sputtering of the oxide layer on aluminum, which improves the weld. At the same time, the thermal load on the tungsten electrode is balanced because it is not constantly overloaded as a cathode.
Metallurgical relevance & risks in welding
The correct application of TIG welding with AC prevents porosity and improves weld quality. However, incorrect polarity reversal or uneven loading can lead to increased oxidation, irregular weld profiles, and reduced throat thickness.
Workshop practice & action instructions
Use an AC power source with the correct frequency (usually 50-60 Hz) and appropriate voltage. Make sure the electrode is cleaned regularly and the polarity reversal is stable. Uneven loading or faulty polarity reversal can lead to damage.