Penetration form of DC TIG arc welding using flux‐cored wire filler. Study of low‐speed DC TIG welding (3rd Report)

Summary Previous reports have shown that the penetration ratio (penetration depth/bead width = D/W) during DC TIG arc welding of SUS304 stainless steel can be improved by using flux‐cored stainless steel wire for CO2 gas welding. The present paper further examines the effect of flux‐cored wire on penetration, considering the mechanism of penetration forming with regard to changes in arc phenomena. The paper shows that a shrunken anode is formed just under the electrode when flux‐cored wire is used. High D/W welds are then obtained without any penetration effect being caused by small quantities of elements in the base metal. The notion of the high D/W being mainly due to electromagnetic convection generated by electric current concentrating in the shrunken anode is also clarified by the experimental approach. For stable welding with high D/W penetration, the paper proposes a method of intermittent supply of flux cored wire just before step‐movement welding starts.