On a recent 2205 project (small vessels and small/medium piping) we some trouble with the GTAW root passes (ASTM A923), but GMAW turned out to be very reliable on medium diameter piping and vessels (horizontal-rotated position), in terms of ferrite/austenite balance and corrosion testing. We did not attempt FCAW but I would recommend synergic pulsed GMAW with 0.045 or 0.035" wire. If you want to avoid Far East sources, which can be mandatory in the USA, Sandvik is the only way to go.
UNS S32205 has become the de facto standard for 2205 base metal, and it means freedom from nitrogen-bearing shielding gases that were necessary with S31803.
My very broad experience is that the higher you go up the CRA ladder, the more cost incentive there is to use GMAW, while FCAW seems to grow more challenged technically (though more user-friendly).
Hope this helps.
"Everyone is entitled to their own opinions, but they are not entitled to their own facts."
Make sure that he raw material is UNS S32205 (widely available in Europe and the US) and weld with 2209 filler.
I also would rather see GMAW used. FCAW welds may look nice but I have seen more than a few issues.
I would suggest including ASTM A923 in your qualifications, it is a test for secondary phases. This is usually only a problem when inter-pass temps are too high.
Hi Stan000,
A few additional resources may help you in correct evaluations of the above processes for welding DSS. Both FCAW and GMAW are proven processes for DSS, with pros and cons.
For FCAW: Pros,very adaptable process for all welding positions. The Cons- when it comes to impact properties, FCAW welds are grossly inferior than GMAW and many other process, due to excess oxygen in the weld metal. Also the presence of CO2 in the shielding gas may impair corrosion resistance.
Please go tough the explanation of clause 4.4 of API Technical Report 938 C and the following docs from TWI UK for guidance.
I guess I'll be the odd man out here but we've had good success using FCAW on 2205 Duplex. I'm basing that on achieving % Ferrite in the range of 35 - 65. Some procedures run a little tighter. I ran a procedure last fall with ferrite running 49.9 to 59.1, but in my experience most customers will accept ferrite in the 35-65 range. Most applications will also require impacts at -40F, Hardness testing and a corrosion test.
Others may have had success with GMAW but beware of the potential for non - fusion.
