Abstract A-TIG welding is the welding process where powdered activating flux (welding facilitating agent) with oxides such as TiO2 and Cr2O3 as the main constituents is dissolved by volatile solvent, such as methyl ethyl ketone and acetone and is applied using a brush, in advance, on the base metal surface which is then subjected to TIG welding.1 A penetration depth of 2–3 times that of a conventional TIG weld can be obtained in the case of stainless steel by means of A-TIG welding, so A-TIG welding has attracted attention as a method to improve TIG welding workability.2