Hello welder77, I can understand where the confusion can come into play. Modes of transfer are often used to describe GMAW welding; wire diameter, voltage, amperage(generally tied to wire speed), type and capacity of power source, type and make-up of shielding gas are all factors which will determine the particular mode that is seen in the arc and at the puddle. In general GMAW processes require at least 80% argon in the shielding gas to allow a true spray transfer to be achieved.
FCAW on the other hand, is a whole different breed of cat and should not be directly compared when considering transfer modes. The parameters that you described for your dualshield set-up would be considered spray transfer. Since the dualshield wire is a cored wire there are additives in the flux that will allow spray-transfer type arc action unlike the solid wires which do not have these types of additives. Normally when I have seen characteristics of dualshield wires that would indicate globular transfer they appear to produce excessive spatter of a very large and easily notable size, the sound is also that of crackling and popping. The bead will also be narrow and stacked up and not flowing out and making a nice transition between the toes of the weld and the parent metal. To fully understand the differences you would need to look at the chemical analysis of the fluxes and see how they react with the arc and the shielding gases, the majority of shielding gases used on the FCAW-g process will consist of straight CO2, 75%Argon/25%CO2, and for some, 90%Argon/10%CO2. Consider that FCAW-g has the possibility to operate in a spray mode of transfer even though it is shielded with gases that are less than 80% Argon content, this is due to the additives that are contained in the fluxes and this is also where the two processes differ greatly. Solid wires on the other hand have a myriad of combinations of shielding gas possibilities; normally starting with straight CO2 and continuing with bi-mixed gases and tri-mixed gases. They can be alloyed with deoxidizers which will aid with puddle fluidity, cleaning action of the arc, and wetting ability, but they don't contain elements that act in the same fashion as the FCAW-g wires with regard to other characteristics.
For any of the processes, the indicator that typically supports the idea that the welding is taking place in the spray mode of transfer has to do with the characteristics of the arc itself; the wire will look as if it is pinching off above the weld pool and you will not see any erratic blobs or nodules forming and transferring from the end of the wire, it will also probably not have the sound of frying bacon, instead it will generally be a fairly quiet and steady sound like a low hiss. I am hopeful that others will chime in here and better educate the both of us. Best regards, Allan
AWS's Ninth Edition of the Welding Handbook Volume 2 Welding Processes, Part 1 designates mild steel electrodes as EXXT-1 & -1M w/CO2 spray transfer, T-2 & -2M spray transfer, T-3 spray transfer, T-4 self shielded w/globular transfer, T-5 & -5M globular transfer w/75-80% Ar w/CO2, T-6 self shielded w/spray transfer, T-7 self shielded w/spray transfer, T-8 self shielded w/spray transfer, T-9 & -9M spray transfer w/CO2, T-10 small droplet transfer, T-11 self shielded w/spray transfer, T-12 & -12M spray transfer, T-13 self shielded w/short-arc transfer, T-14 self shielded spray transfer, T-G not covered/not specified & T-GS self shielded & single pass. The "M" designator classified 75-80% Ar/balance CO2 if no designator 100% CO2.
IMHO FYI - Solid steel wire needs 80% or more Argon. Shielding gas flow rates 30-40 cfh. Transition current/amperage between globular transfer and spray transfer requires a minimum 150-175 amps. Voltage must be greater than 24 volts. Use the lowest possible voltage to maintain the shortest arc length. Contact Tube recessed behind nozzle end 1/8 - 1/4 inch. Wire stick out past the contact tube 3/4 to 1 inch.
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