Effect of active flux addition on laser welding of austenitic stainless steel

Abstract

The use of active flux in tungsten inert gas (TIG) welding is known to increase its weld depth. The present paper involves study of active flux laser beam welding (ALBW) of austenitic stainless steel sheets with respect to its effect on plasma plume, microstructure and mechanical properties of the resultant weldments. ALBW performed with SiO 2 as the flux significantly modified shape of the fusion zone (FZ) to produce narrower and deeper welds. Plasma plume associated with the process was considerably smaller and of lower intensity than that produced during bead on plate laser beam welding (LBW). Flux addition during LBW produced thin and rough weld bead associated with humping. The development of such a weld bead is cause by reversal in the direction of Marangoni flow by oxygen induced inversion of surface tension gradient, widely fluctuating plasma plume and presence of oxides on the weld pool surface preventing free flow of the melt. Active flux laser weldments exhibited lower ductility than that of bead on plate laser weldments.

High quality welding of stainless steel with 10 kW high power fibre laser

“…A 10 kW fibre laser beam can produce an ultrahigh peak power density of MW mm 22 levels owing to 4?5 mm mrad in beam quality and 100 mm in core diameter of delivery fibre. Some experiments have been made to produce high quality weld joints by using high power fibre laser [1][2][3][4][5][6] and other methods such as laser arc hybrid welding [7][8][9] or activating flux laser welding. 10,11 The authors studies have focused on formation mechanisms of high quality weld joints or defects with a 6 kW fibre laser beam.…”

Influence of welding parameters on distribution of wire feeding elements in CO2 laser GMA hybrid welding

“…A number of experiments have been conducted to investigate the molten metal flow in laser or hybrid welding. [9][10][11][12][13][14][15][16][17][18][19][20][21] Some researchers simulated the fluid flow in the weld pool during laser welding process and suggested that the Marangoni flow driven by the temperature coefficient of surface tension and temperature gradient plays an important role in determining the molten metal flow in the weld pool. [10][11][12][13][14][15] It has been reported that the weld depth can increase in laser welding by addition of surface active elements such as sulphur and oxygen.…”

Experimental and numerical study on laser keyhole welding of 42CrMo under air and argon atmosphere

“…Besides sulfur, oxygen is also found to be an active element. Oxide particles [34,35], such as SiO 2 , TiO 2 , and Al 2 O 3 , and oxygen in shielding gas were found to influence surface tensions. Lu [36] systematically studied weld pool shape in GTA welding with different oxygen content in the argon shielding gas.…”