Stargon CS 90%, 8%, 2% question for SS

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I went to praxair yesterday to exchanged an owner small 60 CF bottle for Tri Mix.  I didn't tell them I wanted the gas to mig stainless steel just but only that I wanted a tri mix (that was my mistake).   I just called them and they said that they can't get Stargon SS in a small bottle just a large bottle which I would have to rent the tank and don't want to rent.  So anyway , can I use Stargon CS for stainless?   My understanding is that using Stargon CS for SS will discolor the metal but I don't care since I'm building a smoker which will get discolored once I start to use it.  Other than the color issue will the Stargon CS work for SS.  The metal is about 18 ga.  I also wanted to know if the Stargon CS is better for mild steel since I own a tank of 75/25 and I would prefer to only have to keep one bottle in my garage for space reasons.  If the Stargon works for both SS and Mild Steel that would be fine.Thanks
Reply:Looks like Stargon CS is:90% Ar8% CO22% O2This mix contains too much CO2 for welding stainless steel.  Yes, it will work.  However, the stainless steel will lose some or all of it's corrosion resistance in and around the weld bead.  You may find that the arc is not smooth, and/or is too hot as well.  Depends on your machine, wire size, and the thickness of the stainless material you're welding.  The O2 in  the mix will make the weld puddle much more fluid; it's likely you won't be able to weld vertical or overhead at all.  98/2 Ar/O2 is used for SS welding in the flat and horizontal positions.  It promotes a hot, fluid puddle that is good for high travel speeds and better wetting of the puddle into the sides of a joint.If you don't mind the weld beads rusting, and having to weld everything in the flat position, then you can go ahead and use this gas.  Otherwise, bite the bullet and swap out for a proper SS gas mix.  Ar/He/CO2, with less than 2.5% CO2 is what you want. Originally Posted by medicinemanI went to praxair yesterday to exchanged an owner small 60 CF bottle for Tri Mix.  I didn't tell them I wanted the gas to mig stainless steel just but only that I wanted a tri mix (that was my mistake).   I just called them and they said that they can't get Stargon SS in a small bottle just a large bottle which I would have to rent the tank and don't want to rent.  So anyway , can I use Stargon CS for stainless?   My understanding is that using Stargon CS for SS will discolor the metal but I don't care since I'm building a smoker which will get discolored once I start to use it.  Other than the color issue will the Stargon CS work for SS.  The metal is about 18 ga.  I also wanted to know if the Stargon CS is better for mild steel since I own a tank of 75/25 and I would prefer to only have to keep one bottle in my garage for space reasons.  If the Stargon works for both SS and Mild Steel that would be fine.Thanks
Reply:If you don't mind the color, 75/25 will work for both.   JgSMAW,GMAW,FCAW,GTAW,SAW,PAC/PAW/OFCand Shielding Gases.  There all here. :
Reply:I don't care about the discolor but I am concerned about the stainless steel rusting is I use this regular Stargon
Reply:As stated above, that mix will leave the stainless less resistant to corrosion than the proper mixes for stainless. The heat of the smoker will probably accelerate the corrosion as well.Also, 18 ga. is on the thin side for MIG welding stainless. The 2% Oxygen in the mix you have won't help any either. If you can't get the proper tri-mix for stainless, you can use Argon with 2 to 5% CO2. 3% is ideal for stainless (Airgas calls it Stainmix).95/5 (5%CO2) is the best compromise for working with stainless and carbon steel, but is usually used in spray or pulsed-spray mode.JohnA few weldersA lot of hammersA whole lot of C-clamps
Reply:Using C25 for mig welding SS WILL cause the bead to rust.Just last year I had to replace an entire bridge rail on an imported trawler because someone had tried to "repair" it with mig and C25.  He had used the right wire but the wrong gas.Weldgault,Surprised at your comment.  I'd think you'd know better.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:I'm not sure but I don't think Stargon CS is the same as C25.  I just want to build a stainless steel smoker.  I have a spool of 316L that I am going to use and no one seems to have a helium to get a tri mix in my city especially for a owner owned 60 cf tank.  I've called Praxair and Air Gas.  I have a tank of 75% 25% which I am not going to use for SS but after getting the tank of Stargon CS from Praxair they told me that I could use it for SS but never said anything about the bead rusting.  But from some of the replies I have received it seems that Praxair was not so forthcoming with using the CS mixture on Stainless.  They never mentioned the rust issue which would defeat the purpose of building the smoker out of SS and using an expensive roll of 316L.
Reply:medicineman,I do a fair amount of marine SS welding.  Consequently, I keep a 330 of Tri-Mix (90%Helium, 7.5%Argon, 2.5%CO2) on hand for short arc GMAW welding.  Not sure if my supplier would provide that mix in smaller quantities.It's been recommended by Ed Craig that a mix of 98%Argon/2%CO2 works well for short arc welding of SS.  The low percentage of CO2 would indicate that the covering gas is not likely to introduce excessive amounts of carbon into the weld bead (which leads to the oxidation/rust) often found when using C25.This is an easy mix for me to achieve with my mixers, but, so far, I've stuck with the Tri-Mix because it's proven itself to me.For thicker material I'll go with pulsed spray transfer using a 98%Argon/2%O2 mix.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:Originally Posted by SundownIIImedicineman,I do a fair amount of marine SS welding.  Consequently, I keep a 330 of Tri-Mix (90%Helium, 7.5%Argon, 2.5%CO2) on hand for short arc GMAW welding.  Not sure if my supplier would provide that mix in smaller quantities.It's been recommended by Ed Craig that a mix of 98%Argon/2%CO2 works well for short arc welding of SS.  The low percentage of CO2 would indicate that the covering gas is not likely to introduce excessive amounts of carbon into the weld bead (which leads to the oxidation/rust) often found when using C25.This is an easy mix for me to achieve with my mixers, but, so far, I've stuck with the Tri-Mix because it's proven itself to me.For thicker material I'll go with pulsed spray transfer using a 98%Argon/2%O2 mix.
Reply:I quess I'm just going to have deal with the rust.  I tried to get a 98% 2% but because of the size of my bottle (60 cf) no body  has it.
Reply:As to the discussion on binary vs. ternary mixes for GMAW of stainless steels, I recently did some tests to observe the effects different levels of CO2/Ar/He have on penetration profiles in CV and pulsed spray transfer modes.I used 98/2 and 95/5 Ar/CO2, along with an Ar heavy and He heavy tri-mix(Ar/He/CO2).  I don't have the exact ratios off hand, but they were common, popular blends from airgas.In CV spray transfer the binary blends performed as expected, producing 7.5mm of penetration, and a bead width of 12-12.5mm.  The narrow, deep profile was attributed to high Ar content as well as marangoni flow assisted by oxygen obtained from the disassociation of the CO2.  When ran again with both tri-mixes both gases resulted in the loss of 2.5mm of penetration and an increase to 14.5mm in bead width.  I attributed this to instability created by the addition of He to the mix along with the lower amounts of Ar.In pulsed spray transfer the results were more of a middle ground, both binary and ternary mixes yielded between 5.6-6mm of penetration and 12.6mm in width, however the tri-mixes produced a slightly wider bead.Now this version leaves out a lot of the data we collected but I tried to highlight the points.  Feel free to point out anything that you disagree with or doesn't make sense.  As for short circuit, we didn't do any testing with that so  cant speak to those effects.  All samples were ran on a Motoman arm and Auto- Axxcess 450 power source.The macro graphs below are 95/5 Ar/CO2 CV and pulsed spray, and He-heavy tri-mix CV and pulsed spray, respectively. Attached ImagesHave we all gone mad?
Reply:Originally Posted by medicinemanI quess I'm just going to have deal with the rust.  I tried to get a 98% 2% but because of the size of my bottle (60 cf) no body  has it.
Reply:Originally Posted by con_fuse9Or... you always wanted that TIG welder anyway...
Reply:A dab will do,Sorry it took awhile to get back.Seems that nearly all the SS spray that I do is "out of position".  You're right though, with the 98%Argon/2%O2 the puddle is too fluid for normal spray.  I use the XMT, 714 feeder, and an Optima pulser for pulsed spray.  Can't remember the last time I used the 251 for SS spray.The helium rich tri-mix is not good for SS spray.Even though I use the Thermco mixer most of the time for mixing my Argon/CO2, I've never tried the 98%Argon/2%CO2 for SS spray.  Haven't tried it for short arc either.  Ed Craig is the one recommending it.  Guess it goes back to using what you're comfortable with and has worked for you in the past.  I put too much labor into some of the marine work I do to have to go back a year from now and repair it (possibly due to wrong gas).  Someday I may have to look into alternatives if helium gets much harder to get, but for now I've stayed with the tri-mix.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:Nice to see some hard data for comparisons snoborder88.  Thanks for posting the cross sections.I think your observations in about penetration match up fairly well with my observations from welding.  Put another way, your tests with tri-mix produced a flat, wider bead than the Ar/CO2 mix tests.  This would seem to agree with the idea that the tri-mix gases wet out better.  It also agrees with the prevailing wisdom that burnthrough on thin stainless steel sheet metal is less likely with tri-mix gasses than it is with Ar/CO2.I don't know if I agree with the comments about He causing arc instability; but there are so many other factors that influence observed arc stability, that I can't argue the point.It would be interesting to see photos of the weld faces also, if you have them and can share them.  I'm curious to see how much spatter was deposited on the surrounding base metal, how much smoke, and how much 'glassy' slag deposits remained on the beads.  These all affect cleanup, and add to the total cost of welding.... Originally Posted by sn0border88As to the discussion on binary vs. ternary mixes for GMAW of stainless steels, I recently did some tests to observe the effects different levels of CO2/Ar/He have on penetration profiles in CV and pulsed spray transfer modes.I used 98/2 and 95/5 Ar/CO2, along with an Ar heavy and He heavy tri-mix(Ar/He/CO2).  I don't have the exact ratios off hand, but they were common, popular blends from airgas.In CV spray transfer the binary blends performed as expected, producing 7.5mm of penetration, and a bead width of 12-12.5mm.  The narrow, deep profile was attributed to high Ar content as well as marangoni flow assisted by oxygen obtained from the disassociation of the CO2.  When ran again with both tri-mixes both gases resulted in the loss of 2.5mm of penetration and an increase to 14.5mm in bead width.  I attributed this to instability created by the addition of He to the mix along with the lower amounts of Ar.In pulsed spray transfer the results were more of a middle ground, both binary and ternary mixes yielded between 5.6-6mm of penetration and 12.6mm in width, however the tri-mixes produced a slightly wider bead.Now this version leaves out a lot of the data we collected but I tried to highlight the points.  Feel free to point out anything that you disagree with or doesn't make sense.  As for short circuit, we didn't do any testing with that so  cant speak to those effects.  All samples were ran on a Motoman arm and Auto- Axxcess 450 power source.The macro graphs below are 95/5 Ar/CO2 CV and pulsed spray, and He-heavy tri-mix CV and pulsed spray, respectively.
Reply:Thanks for responding, and thanks to the OP for allowing me to sidetrack the original conversation.I've read Ed Craig's website.  Seems to me that Ed has a lot of background in the automotive industry, working on sheet metal welding.  My experience is that the automotive industry has different(lower) standards for bead appearance, and cleanliness than most other industries.  If it works, but it's ugly, that's usually OK.  98/2 Ar/CO2 works fine in that environment, so long as the welds are hidden away from the consumer's eye.I wasn't trying to suggest that 98/2 would work better for your applications; hope it didn't come across that way.  Believe me, I know and respect the notion that, "If it ain't broke, don't fix it." Originally Posted by SundownIIIA dab will do,Sorry it took awhile to get back.Seems that nearly all the SS spray that I do is "out of position".  You're right though, with the 98%Argon/2%O2 the puddle is too fluid for normal spray.  I use the XMT, 714 feeder, and an Optima pulser for pulsed spray.  Can't remember the last time I used the 251 for SS spray.The helium rich tri-mix is not good for SS spray.Even though I use the Thermco mixer most of the time for mixing my Argon/CO2, I've never tried the 98%Argon/2%CO2 for SS spray.  Haven't tried it for short arc either.  Ed Craig is the one recommending it.  Guess it goes back to using what you're comfortable with and has worked for you in the past.  I put too much labor into some of the marine work I do to have to go back a year from now and repair it (possibly due to wrong gas).  Someday I may have to look into alternatives if helium gets much harder to get, but for now I've stayed with the tri-mix.
Reply:Here's a few that stood out.  The first is the  Ar and He Trimix pulsed samples, notice the difference in cleaning action between the two. The next is the  He Tri CV, the most spatter out of all of the samples and pretty heavy smoke. Last I'll add the 98/2 and 95/5 CV samples to show the difference the small percentage of CO2 makes in fume generation. Attached ImagesHave we all gone mad?
Reply:I agree 8%Co2 is too high & 25% Co2 will greatly scavenge the chrome leaving basicly an iron brick with little protection. The Co2 comes apart in the arc, the carbon likes iron but it likes chrome even more.Years back we did open arc overlay for chemical plants using Ar/5%Co2 which gave really good bead control and shape. When shape and color had to be the best with no cleanup, Ar/Co2-hydrogen mix was used, it left the same color bead as cold wire tig but ran faster. The hydrogen mix looks miles better than other hard wire open arc mig beads I've ever seen, but when it goes wrong - it's really bad and you can't see it from the top (porosity underneath).I've never been around the 2%Co2 or the helium tri-mix so I can't comment on them. I would suspect the helium would be more fluid on the top and wash the bead toes well.@Sno, I'm impressed with the pulse profiles vs spray on something as sluggish as SS. Was the test to prove process or the economy of 2 part gas vs 3 part?Matt
Reply:Originally Posted by Matt_Maguire@Sno, I'm impressed with the pulse profiles vs spray on something as sluggish as SS. Was the test to prove process or the economy of 2 part gas vs 3 part?Matt
Reply:Originally Posted by sn0border88No, it was largely to demonstrate the effect of various levels of shielding gas elements on penetration, arc stability and bead profile.You expected the pulsed profiles to be deeper or not?