hobart,
I guess, it will become self-explanatory what the differences between SAW fluxes (you may certainly find the properties for these on the web and in appropriate handbooks) and A-TIG fluxes are, as soon as you’ll know what the latter are made of.
A-TIG (Activated Flux TIG) was invented by the Russians. And although I seem to recall that also the US EWI has recently stepped into and offers this technology segment, even nowadays it is they who are leading the scientific field of investigation. However, A-TIG is a permanent subject of research and two major fractions of scientists argue on the physical mechanisms, governing the process. Those ones who want to see established “Marangoni” as the major driving force and even those ones who disagree to that.
The International Institute of Welding (IIW) may provide you with a bunch of publications, see also
http://www.iiwelding.org/Search/Pages/Results.aspx?k=A-TIG. The Annual IIW Assembly 2004 held in Osaka has even focused particularly on A-TIG within its working group meetings (Comm. XII / SG 212) and one might honestly state:
“Yes, the process itself and its results are fascinating!”So the question arises: “Why isn’t it used more often in the field?”
Well, actually A-TIG fluxes are, even nowadays, somewhat afflicted with ‘Black Magic’. That is, nobody, except the “magician” himself who did mix the flux, is most likely able to admit what exactly the flux composition is.
According to [1] and hence definitely different to SAW fluxes, they are consisting of a high number of metal oxides, such as:
• Al2O3 (Aluminium-Oxide)
• MgO (Magnesium-Oxide)
• CaO (Calcium-Oxide)
• SrO (Strontium-Oxide)
• Cr2O3 (Chromium-Oxide)
• MnO (Manganese-Oxide)
• CoO (Cobalt-Oxide)
• Fe2O3 (Iron-Oxide)
• Ga2O3 (Gallium-Oxide)
• In2O3 (Indium-Oxide)
• GeO2 (Germanium-Oxide)
• SnO2 (Tin-Oxide)
• V2O5 (Vanadium-Oxide)
• MoO3 (Molybdenum-Oxide)
• TiO2 (Titanium-Oxide) and
• (SiO2 (Silicon-Oxide)
These constituents are believed to be “activators” for significantly increasing weld fusion depth in stainless steel GTAW.
Professor Konstantin Yushchenko of the famous Ukrainian Paton Welding Institute is one of the globally leading experts in this field and I should like to recommend to you to read his paper [1], see also:
http://www.iiwelding.org/Publications/TechnicalDB/Old%20TechnicalDatabase/PopUp.aspx?ID=4458 presented at the IIW Annual Assembly in Quebec in 2006.
To come to an end. The process, even though proving excellently fusion depth increase, is somewhat 'incalculable' in its conduction. That is, the “activating flux” has to be deposited upon the workpiece surface as a kind of compound layer prior to welding. The result however, is believed to vary as a function of the layer thickness. That is, one has to accurately control the layer thickness by utilising appropriate means (eddy current converter, see also [1]). So you may imagine to be confronted with an increasing number of variables. The flux composition itself and the procedure to use it accordingly for obtaining highly reproducible results. That, at least in my humble opinion, may be assessed the main obstacles impeding a more widespread use of A-TIG in the industry.
Best to you,
Stephan
References:
[1] Paton, B.E. et al. (2006),
“Factors of Increased Penetrating Capacity of A-TIG Welding of Stainless Steel”, IIW Doc. No. XII-1911-06
Here are some articles with actual application data comparing GTAW with and without flux in a .pdf for your review, and I do remember about a post I made on active flux TIG a few years ago here that also had some good comparison data also... So, first I'll post the links I have regarding active flux TIG, and then attempt to answer your other question regarding the differences between the flux used in submerged arc welding & active flux gas tungsten arc welding...
3.2,
