Numerical simulation of the influence of oxygen content on the weld pool depth during activated TIG welding
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ORIGINAL ARTICLE
Numerical simulation of the influence of oxygen content on the weld pool depth during activated TIG welding Anoop K. Unni 1 & Vasudevan Muthukumaran 1,2 Received: 8 May 2020 / Accepted: 2 November 2020 # Springer-Verlag London Ltd., part of Springer Nature 2020
Abstract The required amount of surface-active element dissolved in the weld pool remarkably influences the depth of penetration during activated tungsten inert gas (A-TIG) welding process. This is mainly attributed to the changes in the surface tension coefficient sign by oxygen content, which in turn controls the reversal of fluid flow and the nature of heat transfer. It emphasizes that there is a strong correlation between the surface-active element oxygen content and the development of the weld pool. This research intends to find out the critical oxygen content required in the weld pool to cause complete reversal of Marangoni flow and its influence on the weld bead dimensions by numerical simulation during A-TIG welding. Three-dimensional evolution of thermal and velocity fields in the weld pool is simulated using ANSYS Fluent for 200 A and 300 A welding currents respectively by altering the dissolved oxygen levels in a 0.01 m thick 316 LN stainless steel (SS) plate. The simulated weld bead profile for varying dissolved oxygen levels is validated for 300 A current by carrying out A-TIG welding experiments in a 0.01-m–thick plate with different fluxes in order to achieve the diverse amounts of oxygen content in the weld pool. The simulated and experimentally obtained weld bead dimensions exhibited good agreement for various dissolved oxygen contents in the weld. The complete reversal of fluid flow has been found to occur in the weld pool when the dissolved oxygen in the weld pool is 335 ppm at 300 A and 200 ppm at 200 A current. Keywords Numerical simulation . Activated TIG welding . AISI 316 LN stainless steel . Marangoni convection . Surface-active element
1 Introduction Advanced welding processes among fusion welding processes have profound influence in joining thicker sections of stainless steel. High-quality welds are often obtained by achieving full penetration without defects by employing optimized welding parameters. Advanced TIG welding processes, Laser and Laser-Hybrid welding, are very useful in producing betterquality weld joints. Activated TIG welding is a novel variant of TIG welding process that uses predominantly oxide fluxes to increase the penetration of weld metal. Gurevich et al. [1] reported enhanced depth of penetration up to 2.5 times than
* Vasudevan Muthukumaran [email protected] 1
Homi Bhabha National Institute, Maharashtra, India
2
Materials Development and Technology Division, Metallurgy and Materials Group, Indira Gandhi Centre for Atomic Research, Tamilnadu, India
the conventional TIG process by applying a layer of flux on top of the titanium alloys just prior to TIG welding. Dey et al. [2] developed in-house activated flux and achieved full penetration in a single pass for A-TIG welding of titanium on
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