TIG and Stainless MIG Same Gas?

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From my research, it seems that a 98/2 argon/co2 mix is best for stainless mig.  I'm also considering getting a TIG, which requires 100% argon.  I'm also tight on space and funds, so I'm trying to get this both done with one tank and gas fill.Does anyone think I could TIG with 98/2 gas or could I MIG stainless with 100% argon?Before anyone says I can use 75/25 for MIG stainless, I only have one bottle, and no other gas handy.Thanks!
Reply:NO and NO.Not happening.Tig stainless=100% ArgonMig stainless=Tri mix (90% Helium, 7.5% Argon, 2.5% CO2)For spray transfer on SS, a mix of Argon and 1% or 2% O2 is recommended.  This mixture is NOT recommended for short arc welding.PS.  Not sure where you're doing your "research" but what you're quoting doesn't follow industry guidelines.  An Argon rich mix (92% Argon, and 8% CO2) is recommended for spray transfer on mild steel.  Another recommended mix for spray transfer on mild steel is 98% Argon, 2% O2.Maybe you should hold off on getting that tig til you can see your way thru to feeding them the right gas.Last edited by SundownIII; 05-25-2009 at 03:39 PM.Syncro 250 DX Dynasty 200 DXMM 251 w/30A SG XMT 304 w/714 Feeder & Optima PulserHH187Dialarc 250 AC/DCHypertherm PM 1250Smith, Harris, Victor O/ASmith and Thermco Gas MixersAccess to a full fab shop with CNC Plasma, Water Jet, etc.
Reply:From my research, it seemed that helium tri-mixes weren't optimal for gauge stainless.  Is this guy wrong?http://www.weldreality.com/MIG_welding_gases.htm"Argon - 2% CO2 Benefits Gage Parts : In contrast to the higher energy and higher voltages required from a 90% helium 7.5%% Ar - 2.5% CO2 tri-mix, the much lower cost and more gas in the cylinder, argon - 2% CO2 mix, will when short circuit or pulsed welding thin gage (<2.5 mm) stainless;[a] reduce weld burn through potential,[b] reduce weld distortion potential,[c] reduce weld oxidation potential,[d] reduce the potential for all forms of weld cracking.[e] reduce volt requirements more comfortable for the welder,[f] reduce stainless weld fumes, "Last edited by clearchris; 05-25-2009 at 03:46 PM.
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Reply:Sorry, you're not going to be able to tig and mig with the same gas bottle.  You can use one gas bottle if you use your tig for the stainless instead of the mig and use self shielding fluxcore wire in the mig for carbon steel, so you'll only need one bottle:  pure argon for the tig and be able to weld all metals efficiently with minimal equipment (if your tig has AC for aluminum).MM350P/Python/Q300MM175/Q300DialarcHFHTP MIG200PowCon300SMHypertherm380ThermalArc185Purox oaF350CrewCab4x4LoadNGo utilitybedBobcat250XMT304/Optima/SpoolmaticSuitcase12RC/Q300Suitcase8RC/Q400Passport/Q300Smith op
Reply:Dakook,In the first photo you'll notice a Thermco gas mixer used for mixing Argon/CO2.In the second photo you'll notice two (2) Smith mixers.  One is for mixing Argon/O2 and one is for mixing Argon/He.In the third, you'll see a 330 bottle of tri-mix for SS mig (blue/geen bottle)I sure as he11 wouldn't keep a 330 of expensive gas around if it didn't work best for me.  I do a lot of marine fab/repair and I can assure you, that the proper gas has a lot to do with how a weld stands up to the environment.If you're so inclined to follow the advice of one individual, who's advice goes against industry standards, then so be it.  My advice is based on first hand experience with many different covering gases. Attached ImagesSyncro 250 DX Dynasty 200 DXMM 251 w/30A SG XMT 304 w/714 Feeder & Optima PulserHH187Dialarc 250 AC/DCHypertherm PM 1250Smith, Harris, Victor O/ASmith and Thermco Gas MixersAccess to a full fab shop with CNC Plasma, Water Jet, etc.
Reply:clearchris,When you speak of "gauge" stainless, it depends on the gauge you're referring to.  For really thin stainless, mig is not my first choice of options in the first place.  Too difficult to control the heat and warpage with mig.  Generally gets tigged.On 1/8" material and heavier, I prefer the tri-mix because of the puddle achieved, while still maintaining the weather resistance of the base material.Syncro 250 DX Dynasty 200 DXMM 251 w/30A SG XMT 304 w/714 Feeder & Optima PulserHH187Dialarc 250 AC/DCHypertherm PM 1250Smith, Harris, Victor O/ASmith and Thermco Gas MixersAccess to a full fab shop with CNC Plasma, Water Jet, etc.
Reply:Sundown,That is very nice equipment you have there. My post was not meant to cast dispersions on you. However looking at it in the total context I see how you could take it that way and for that I apologize. I think with Ed Craig and his recommendations it's all about the total cost of the weld. However it does point out that there is more than one way to skin a cat.
Reply:I should have been more precise in my original post.  I said "gauge stainless" but meant "thin gauge stainless."  1/8 inch thick would be thicker than I ever foresee needing.So, I'll summarize the collective wisdom:1)  It sounds like the tri-mix is mostly for 1/8 thick or larger and spray transfer.2)  Spray transfer on stainless can be done with argon and a small amount of o2.3)  Ed Craig's advice is all about what can be done for minimum cost.4)  SundownIII has some really sweet equipment.Going forward:1)  My puny Lincoln 3200HD probably can't mig 1/8 SS so I shouldn't worry about tri-mix.  I'm certainly not getting any spray transfer with it.2)  I should really invest in a TIG for thin gauge stainless.  (I need a second job.)3)  Begin sucking up to SundownIII right now so maybe when he upgrades, he'll let me buy some of his cast-offs.I'm really surprised the salesman graphic made it into the thread, I was almost certain someone was going to cut and paste the butt picture instead.  I mean, c'mon, this is weldingweb.    Either way, I'm sure it was posted in humor and it wasn't pointed.BTW, this does mention C2 for stainless, so it's not without precedent...http://files.aws.org/wj/2006/02/wj20...j200602-46.pdfThese all mention 98/2 mix for stainless.http://weldingweb.com/vbb/showthread.php?t=4904http://weldingweb.com/vbb/showthread.php?t=9154http://weldingweb.com/vbb/showthread.php?t=18081http://weldingweb.com/vbb/showthread.php?t=13648Last edited by clearchris; 05-26-2009 at 11:03 PM.
Reply:Chris,Tri-mix is -usually- used for short-circuit transfer with GMAW on stainless.For spray transfer GMAW on stainless, the usual gas is 98-2 argon-O2.All like sundown said above.And as sundown also said above, GMAW on thin-gauge stainless is easy to warp.TIG is plain argon for almost everything, or an argon-helium blend for more penetration/heat/ooomph.  Originally TIG was called Heli-arc (trade-marked name IIRC) because it used pure helium.  Then they found out that argon worked fine for most everything and was less expensive than helium.  Different versions of the Lincoln manuals for the small MIG machines (120 volt versions and the 175-class 240 volt versions as well) seem to variously call out for either 98-2 or tri-mix for use on stainless steel with 0.030 308 stainless wire (or sometimes 0.035 308 wire for the 175's).And again as sundown said, the gas is important to the weld.  The gas or gas mix has to be appropriate for the parent material, the filler, the process, and the end environment.  The best laid schemes ... Gang oft agley ...