During at least part of the pickling phase, feed of the auxiliary current to the pilot arc circuit is arrested and the main circuit and the pilot arc circuit are fed by the main current. Plasma arc welding of aluminum and aluminum alloys, comprises: (a) initiating a pilot arc by means of an auxiliary current delivered from an auxiliary source of current and circulating in a pilot arc circuit; (b) feeding with plasmagenic gas; (c) initiating the main arc by means of a main current delivered from a main current source and circulating in a main current circuit; (d) cyclically varying the polarity of the main current in a manner to obtain a pickling of the material at a first current polarity and at least one phase of welding of the material at a second current polarity. ADDITIONALLY CLAIMED is the plasma arc welding device.
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