A Study on the Applicability of A-TIG Welding of Semi-Automatic Cold Wire Feeding Process for Cryogenic Stainless Steel Pipes

Abstract

Activated Tungsten Inert Gas (A-TIG) welding with deeper penetration characteristic than manual Tungsten Inert Gas (TIG) welding is one of developed TIG welding processes for higher welding productivity. However, underfill phenomena often occurs when A-TIG welding applies to butt joints of Stainless steels with gap and misalignment. In order to complete welding, additional welding passes are needed. To prevent the underfill phenomena, A-TIG welding using semi-automatic cold wire feeding process can be one of alternatives. In this study, semi-automatic cold wire feeding condition for sound A-TIG weld profiles and characteristics of A-TIG welds were investigated. A-TIG welds without underfill were obtained by front feeding and placing the wire at the point about 1mm below from a TIG welding electrode. On the basis of mechanical and corrosion test results, A-TIG welds using semi-automatic cold wire feeding process have similar mechanical and corrosion characteristics with manual TIG welds, although slag was remained on the weld beads after the pickling process to remove heat tints of the A-TIG welds. However, the slag on the bead of A-TIG welds had no correlation with pitting corrosion.