Method and apparatus for TIG welding

A method of TIG welding in which a plurality of spaced nonconsumable electrodes extending from the head of a welding torch are placed in a protective atmosphere formed by inert shielding gas emitted from the head of the welding torch which can travel along a weld line of base metal, and a filler wire is also fed into the protective atmosphere to carry out welding of the base metal, which method comprises:

• projecting the plurality of nonconsumable electrodes from the head of the welding torch toward the weld line;
• passing the filler wire at least once around a ring-shaped passage for giving it a permanent set, and then passing the filler wire through the space between the electrodes extending from the head of the welding torch for feeding the filler wire, the filler wire bending toward one of the electrodes due to the permanent set;
• supplying welding voltage and current independently to the respective electrodes;
• producing a single molten pool by melting the base metal and filler wire with arcs generated between each electrode and the base metal, and;
• controlling weld penetration and fusion of the base metal chiefly with arc plasma from one of the nonconsumable electrodes and melting the filler wire chiefly with arc plasma from the remaining electrodes.