Research On A-TIG And A-LBW Of Austenitic Stainless Steel

Nowadays, production efficiency improvement is the most important direction of the welding techniques development. The activating fluxes coating the surface of the welding sheet can effetely solve these problems. Based on the research on TIG, low-power pulse laser welding and fiber laser welding of SUS304 with activating fluxes (TiO₂,SiO₂,Cr₂O₃,CaF₂,NaF)both in single and formula ways, the effects of the fluxes on the penetration of joints, as well as the mechanism of penetration improvement, were studied. The results are helpful for the further application of the activating fluxes in both TIG and laser techniques.The results show that when the oxides fluxes were used in the TIG and low-power pulsed laser welding, the penetrations and D/W ratios can be changed significantly. However the fluorides have little effect on these. With reference to this, the theory of marangoni convection variation in the weld pool is verified.The difference in the fiber laser welding with fluxes is: fluorides play much more important role in the penetration improvement. The fiber laser has higher power density, higher temperature than low-power pulsed laser. Due to these, fluoride and oxide active fluxes together act and bring about the improvement in weld penetration.The research conducted in this paper is of great significance for the combination of activating fluxes and welding techniques. Another important aspect of this paper is about activating-laser welding. Obviously, the fluxes coating the sheets can increase the absorption rate of laser. When take consideration of the characteristics of laser welding itself, there comes some other reasons for the penetration variation.The existence of activating fluxes not only reduce the plasma effect and enhanced keyhole effect,but also changes the convection of the welding pool, which makes the microstructures within the welding vary. This is the further development of mechanism of penetration improvement.