A few days ago I stumbled on to the web site of the "Navy Joining Center." One topic briefly covered there is their use of GTAW fluxes for carbon steel, stainless steel, copper-nickel, nickel, titanium and cast iron. The fluxes apparently decrease welding time and improve penetration.
Have any of you had experience using these fluxes in GTAW welding?
The page I read is at:
http://www.ewi.org/njc/gtaw.asp
Some years back I read some papers dealing with "A-TIG". From what I can remember, it was a GTAW process using a flux to achieve the results claimed on the website you gave. At that stage I could not find out much info. as it was apparently not commercialized yet. It appears that they have now managed to commercialize the process.
On the website they gave the names of some suppliers of the fluxes. I am sure that these companies would be able to give you some more info.
Regards
Niekie
I haven't used them personally, but the theory is that the fluxes modify the surface tension on the surface of the weld pool, so that the circulation of the molten metal in the weld pool changes from raising underneath the electrode, flowing out towards the edge of the weld, then back down to the bottom of the weld, to sinking underneath the electrode, raising to the edge of the weld pool, and then flowing on the surface to back underneath the electrode. This way, the superheated molten weld metal instead cooling off by flowing out to the edge of the puddle, flows downwards and helps penetration by melting additional base metal. I believe one of the first GTAW fluxes available is called "Solar flux", and should be available at most welding supply outlets.
There is also another kind of flux used with GTAW. The weld is made with a flux cored wire, much like FCAW electrode. It is used when welding from one side, and it is not possible, or practical to shield the root of the weld. The flux from the filler metal is supposed to cover the root of the weld to take the place of sheilding gas (purge gas). However, if you plan on using something like this, make sure it is approved by the powers that be, as it would be detrimental in some applications. (e.g. it can cause crevice corrosion) It is also considered a "stop gap" measure by some, and does not protect the surrounding HAZ like purging does.
G Roberts
Just to keep the thread of conversation on the right path.
Solar Flux is a brand name and comes in two types, Type I and Type B, neither of which is being discussed in the paper by the Naval joining Center. Solar Flux does not increase penetration in GTA welds nor is it superior to argon or helium as a backing gas. It will not produce superior mechanical properties in welds.
Solar Flux is a semi-effective backup in certain situations for stainless and high nickel alloys, Type B for alloys containing less than 25% Nickel and Type I for those over. It is a powder that is mixed in alcohol and brushed on the Backside of a joint as an alternative to argon. Although these fluxes meet the criteria of several mil-specs it is essential that these back up fluxes be used only after engineering approval. Solar Flux is often used as a last alternative in areas that are inaccessible and proper argon backup is not possible. Both Fluxes leave a residue rendering them unusable in many aircraft and sanitary operations.
I have managed to get into contact with someone at Liburdi Dimetrics who apparently manufacture these fluxes. He/She will let me have more info. If I get it, I will let you have it.
Regards
Niekie
I've witnessed the use of these kind of fluxes on stainess steel
during a fellow student's master thesis at the Royal Institute of Technology in Stockholm. The results where remarkable.
Example:
U 15 V
Q 2.9 kJ/mm
Gas Ar50/He50
Penetration without flux: 5 mm
Pnetration with flux: 9 mm
These fluxes where, as far as I know, first developed in Russia back in the sixties by Paton Welding Institute in Kiev, Ukraine (penetration is good for armour and titanium submarine hulls) and some fluxes are available on the market.
Commercial Fluxes:
Paton Welding Institute (available from Welding technology center):
PATIG-S-A (C-Mn, alloyed, Cr-Mo, and stainless steels)
PATIG-N-A (Ni-alloys)
Navy Joining Center (available from EWI, Hobart-Miller and Liburdi Engineering)
FASTIG-SS7 (stainless steels)
CS-325 (C-Mn, alloyed, Cr-Mo)
Fi-600 (Ni-alloys)
These commercial fluxes can be very expensive (around 6000 USD/kilogram for FASTIG-SS7). But it is not that hard to manufacture your own flux (150 USD/kilogram).
The flux is a powder which is mixed to a paste by adding acetone. The paste is then applied as a thin layer with an ordinary "artist-sized" painting brush. After the paste has dried that You weld as usual.
For stainless steels the flux consists of roughly 50% (volume) SiO2 and 50% TiO2 (according to my friend's thesis).
Best regards:
Happy (EWE)
you are right. the commercial A-TIG flux is very expensive. however, you can make the flux yourself by this method.
I have do many works in A-TIG welding with flux since last year. it is a innovative variant of GTAW welding, and is also remarkable.
the material can be carbon steel, stainless steel , titanium alloy, nickel based alloy etc. the power souce used is same as conventioanl TIG welding. the penetration depth can be increased up to 300% compared with conventioanl TIG welding.
This method was invented by Paton Institute of Welding in the 1960s for welding of titanium alloy, and spreaded in the 1990s by EWI and TWI.
another benefit from using flux for titanium alloy is that it can reduce the percentage of porosity greatly.
the principles of A-TIG are two aspects, one is that it can constrict the arc greatly, and another reason is that the flow direction is changed due to the change of surface tension gradient.
the mechanical properties of weld made with a-TIG is similar to the weld with C-TIG.
anyway, it has a great propspet in substituting the conventioanl TIG welding.
regards,
Sanbao Lin
I received a couple of data sheets from Liburdi Dimetrics regarding two different fluxes they sell for A-Tig. I asked them for cost as well, because this info. is not on the data sheets. If you want, I will forward this to anyone that is interested. Just make sure that you give me your e-mail address.
I also received a powerpoint presentation, but it is in Dutch, so I recon it will not help you much. (As a South African, I have a reasonable grasp of Dutch.) At any rate, it is a huge file that took me ages to get downloaded. The info is also not much more than was in the data sheets.
The people at Liburdi Dimetrics appear to be quite helpfull. (No I do not have shares in the company.)
Regards
Niekie Jooste
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