Direct current TIG (DC) welding is when the current flows in one direction only. Compared with AC (Alternating Current) TIG welding the current once flowing will not go to zero until welding has ended. In general TIG inverters will be capable of welding either DC or AC/DC welding with very few machines being AC only.
DC is used for TIG welding Mild Steel/Stainless material and AC would be used for welding Aluminium.
This method of welding can be used for a wide range of materials. The TIG welding torch is connected to the negative output of the welding inverter and the work return cable to the positive output.