High speed tandem TIG welding of ferritic stainless steel plate

Weld humping and undercut are the most common appearance defects in high speed welding.A high speed tandem TIG welding process was developed to suppress the formation of these appearance defects and to improve the productivity of TIG welding.In this paper,the mechanical properties and microstructure of joints obtained from tandem and single TIG welding were tested and compared.The results show that the sound weld appearance can be obtained by tandem TIG welding at the welding speed of 3 m/min for 1.5 mm thick 409 L stainless steel plate.The mechanical properties of the tandem TIG welded joint are in the similar level with single TIG welded joint.The analysis of the tandem TIG welding process indicates that the assistant arc with a push angle can prevent the liquid metal flowing backward to the trailing region of weld pool and the premature solidification of thin liquid layer in the gouging region.