TIG welding wire and gas discussion

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Hi, I was at the local welding distributor (Praxair) the other day looking for some small 70S-2 weld wire (like .035 or smaller) and they could only get 10lbs of it. That is way too much for us and the smallest size that they could get was .045, which was too big. The sales rep suggested that if I don't mind it not being in 3' lengths and don't mind if it comes off a spool, then I could try and use some MIG welding wire and just cut off a length of what I need. He says that it is the same stuff. Is this right that it is the same material just different sizes and one is on a spool instead of in 3' lengths? If this is the case I was able to get some .023 Dia. 70S-6 in a two pound spool. What is the difference with 70S-2 and 70S-6 For TIG welding? I can get both of them for TIG.If this is true that the wires are the same then I asked the guy about the gas because I know that wen I MIG weld I use 75-25% Argon-CO2 mix and when I TIG weld with the same material I use Pure Argon. I am not arguing that Argon is the best gas for TIG but can the 75-25% mix be used for TIG welding too? Has anyone tried it? What could happen and what could it hurt? Also why is one gas used in one process and another type used for another process? They are accentually the same concept of melting metal and adding a filler metal to it, aren't they?Just a reminder, I am not arguing the gas that is best to use, I am just trying to get answers that I couldn't get from the guy at the welding store so I thought I might ask here.Thanks guys.Miller Mulitmatic 200Lincoln POWER MIG 180Thermal Dynamics Cutmaster 51Oxy-Acetylene TorchMiller Digital Elite Vintage USA
Reply:it has been tryed was a thread about using the Mig mix for Tig and IT DON'T work tungsten does not like it  stick with Argon and you CAN use Mig wire as Tig filleridealarc 250/250 ac-dc tigidealarc 250/250 ac-dc tig #2 used for sticklincoln sp100hh125dual arbor grinder polisher30 yrs of hand tools52 pitch blocks 6p-26prake gauge -pitch gaugeG&D prop repair 918-207-6938Hulbert,okla 74441
Reply:Originally Posted by Mr. MohonHi, I was at the local welding distributor (Praxair) the other day looking for some small 70S-2 weld wire (like .035 or smaller) and they could only get 10lbs of it. That is way too much for us and the smallest size that they could get was .045, which was too big. The sales rep suggested that if I don't mind it not being in 3' lengths and don't mind if it comes off a spool, then I could try and use some MIG welding wire and just cut off a length of what I need. He says that it is the same stuff. Is this right that it is the same material just different sizes and one is on a spool instead of in 3' lengths? If this is the case I was able to get some .023 Dia. 70S-6 in a two pound spool. What is the difference with 70S-2 and 70S-6 For TIG welding? I can get both of them for TIG.If this is true that the wires are the same then I asked the guy about the gas because I know that wen I MIG weld I use 75-25% Argon-CO2 mix and when I TIG weld with the same material I use Pure Argon. I am not arguing that Argon is the best gas for TIG but can the 75-25% mix be used for TIG welding too? Has anyone tried it? What could happen and what could it hurt? Also why is one gas used in one process and another type used for another process? They are accentually the same concept of melting metal and adding a filler metal to it, aren't they?Just a reminder, I am not arguing the gas that is best to use, I am just trying to get answers that I couldn't get from the guy at the welding store so I thought I might ask here.Thanks guys.
Reply:Yes, MIG wire is identical in composition to TIG wire of the same specification.  I would stick with using S-2 wire, no need for the high Si content that you would find in S-6.  WIll it hurt?  Doubtful, but that's just my preference.As for the shielding gas and why one is used for one process and not the other... thats a rather long answer.  In short, a Ar/CO2 mix is used in GMAW because pure Ar does not offer enough "heat" to produce a stable weld pool.  The CO2 also aides in puddle fluidity and increases penetration.  Pure Ar is used for GTAW because any reactive gas present in the arc (CO2/O2/N/ect.) will cause the tungsten to rapidly oxidize and be consumed, creating a very erratic arc and inclusions in the weld bead.That's a really short answer to a really long question that some people could write a doctorate thesis on.  Look here for a little more info on the subject.http://www.thefabricator.com/article...or-arc-weldingHave we all gone mad?
Reply:Er70s6 is a designation for the wire doesn't care if it is mig welded or tigged its all the same.Its er70s6  or er70s2.Take 10 to 15 feet of the mig wire put one end tight in in your vise and the other end in your drill pull the trigger as you pull it tight and straight,in a few turns it will be just as straight as tig rod and easy to feed with your fingers.You can watch it straighten out.I have done it dozens of times nice to work with.I usually make up about 30 36" lengths and then cut them in half much easier to store and work with.I have .023" .035" .045" all from mig wire.Great for tig work on body panels.My 2¢V.
Reply:Great thanks for all the great info guys. Helps a lot.Miller Mulitmatic 200Lincoln POWER MIG 180Thermal Dynamics Cutmaster 51Oxy-Acetylene TorchMiller Digital Elite Vintage USA