Mig welding SS. Questions

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Going with my first SS project, I plan on making a vband downpipe for my car.What mix should I go with? I would prefer a mix that I can use on SS and mild steel so I don't need multiple tanks. So would 98argon/2% co2 work well for me or tri mix? Straight argon? Also with a mig do I need to back purge? If so what do I need and how do I set it up?Up until now I have only done mild steel. Any help is appreciated.
Reply:try looking through the search feature of this forumwas some threads done on this welcome to the forum..   it's a good placeidealarc 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:I found a lot of info, but what is spray arc vs short arc?Torchmate 2x2 CNC with Flashcut CNC controlsHypertherm Powermax45 Esab ET220i Razorweld 195 MigRazorweld 200ac/dc TigTormach 770, Tormach xstechRazorweld, Vipercut/Vipermig, SSC Foot Pedal Dealer
Reply:With your welder, you don't need to know.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 GambleWhat mix should I go with? I would prefer a mix that I can use on SS and mild steel so I don't need multiple tanks. So would 98argon/2% co2 work well for me or tri mix? Straight argon?
Reply:Thanks for the info. I was under the impression you only back purged on a tig. But I'll have to search and figure out how to do it on my machine.So does my machine do short arc only?Torchmate 2x2 CNC with Flashcut CNC controlsHypertherm Powermax45 Esab ET220i Razorweld 195 MigRazorweld 200ac/dc TigTormach 770, Tormach xstechRazorweld, Vipercut/Vipermig, SSC Foot Pedal Dealer
Reply:Purging isn't something that is done by the machine, or involves one at all.  You need to either install a Y-fitting after the regulator on your tank with a hose that will feed the gas into the space to be purged, or get a dual-regulator setup so that you can independently control the flow rates.I have always used a T or Y fitting and it works just fine, I suggest that is the way you go as the other would require buying a new regulator.  But don't forget about the solar flux, for a one-time use that would probably be your best bet as you wouldn't have to purchase another tank of Ar.Your machine lacks the power to do anything other than short circuit.Have we all gone mad?
Reply:If you do a Y fitting do you need 2 tanks for back purging?If I do the solar flux, any specific kind? And after I mix it and put it on the pipe how long is it good for? By that I mean can I put it on the inside of the pipe, weld some and come back the following day and weld more. Or is it only good for say a few minutes to a few hours?Torchmate 2x2 CNC with Flashcut CNC controlsHypertherm Powermax45 Esab ET220i Razorweld 195 MigRazorweld 200ac/dc TigTormach 770, Tormach xstechRazorweld, Vipercut/Vipermig, SSC Foot Pedal Dealer
Reply:Originally Posted by GambleIf you do a Y fitting do you need 2 tanks for back purging?If I do the solar flux, any specific kind? And after I mix it and put it on the pipe how long is it good for? By that I mean can I put it on the inside of the pipe, weld some and come back the following day and weld more. Or is it only good for say a few minutes to a few hours?
Reply:Just use argon / 1.5% O2 mix for shield gas GMAW / MIG stainlessNo need to purge using GMAW stainless tube in non critical applications. If you don't want internal heat tint, purge with pure argon.CV Rectifier + Wire feedar - spray / dip depends on current. Thin wall dip, (short circuit) / heavy wall spray. Pulse - Enables spray type transfer at low current where short circuiting mode normally occurs - preferred.Let's take the BS out of welding......
Reply:Originally Posted by chrispc66Just use argon / 1.5% O2 mix for shield gas GMAW / MIG stainlessNo need to purge using GMAW stainless tube in non critical applications. If you don't want internal heat tint, purge with pure argon.CV Rectifier + Wire feedar - spray / dip depends on current. Thin wall dip, (short circuit) / heavy wall spray. Pulse - Enables spray type transfer at low current where short circuiting mode normally occurs - preferred.Let's take the BS out of welding......
Reply:Seems like everyone does something different. I even got a few pm's saying to just use 75/25 mix. Anywho the local welding supply store won't give me a tri mix or a 98/2 mix without getting a 300cu tank. I got the wire and a new contact tip .030 today and tried it out. My heat settings are A-E. I tried it in the middle on C and one lower on B. After I weld the puddle seems to expand and move around. It's weird, but not on low setting (A).Also on B and C it will burn a hole in 3/4" or less. Also seems to be bubbly when it's done.Torchmate 2x2 CNC with Flashcut CNC controlsHypertherm Powermax45 Esab ET220i Razorweld 195 MigRazorweld 200ac/dc TigTormach 770, Tormach xstechRazorweld, Vipercut/Vipermig, SSC Foot Pedal Dealer
Reply:Originally Posted by sn0border88And why exactly would one want to us a 1.5% O2 mix on thin stainless instead of tri-mix, especially considering the limitations of the machine?GMAW-P still requires a high current to spray, it just has a lower overall heat input.Plenty of reasons to purge on this pipe, considering the heating cycles it will be exposed too.Take the BS out of welding and do your homework first.
Reply:Oh and in case you need to add more BS / undue complexity, may I suggest you keep posts relevent to the OP request instead of hijacking a thread by demeaning other users trying to do just that
Reply:I don't like to change my wire on my MM252 between steel and stainless, so I bought a little 220v Lincoln 175HD and use it for all my stainless mig welding.  The only gas it has ever used was 75/25 (argon/co2) and it has done just fine.  I know that tri-mix is preferred and also some gas companies have their own specialty mixes that vary percentages of the argon, helium and co2 etc, but for my quick and dirty stainless mig jobs, I just use the old 75/25.  The welds won't be as pretty as trimix and certainly don't look like tig, but it definitely gets the job done.  On a stainless exhaust system, I would be more likely to use the mig to spot-weld the joints, then use tig to complete the welds, but if i'm in a hurry, it's mig.Miller Syncrowave 350Millermatic 252/ 30A spoolgunMiller Bobcat 225g w/ 3545 spoolgunLincoln PowerArc4000Lincoln 175 Mig  Lincoln 135 Mig Everlast 250EX TigCentury ac/dc 230 amp stickVictor O/AHypertherm 1000 plasma
Reply:chrispc,Let me get this straight.You come into the thread with a bunch of garbage with no basis in fact.  You don't answer the OP's question about what spray arc transfer is.  You are wrong about pulse allowing you to spray at lower amps (pulsed spray allows welding at lower AVERAGE amps thereby reducing the overall heat in the bead.  The high amps are still required for spray transfer)Then you tell another poster to knock off the BS.What kind of clown are you?Maybe you want to tell ME that I don't know what I'm talking about when it comes to welding stainless steel.Talk about BS.  Your 1.5%O2 mix is just that.  Who the heck mixes that for you?  I think you're confused with a 98%Argon/2%O2 mix which is a good mix for spray transfer on mild steel (hot).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 chrispc66LMAO - CO2 has nothing to offer SS except tying up chrome and depleting the weld some. O2 produces a more constricted / hotter arc - good for short curcuit at low current.GMAW-P is controlled droplet transfer - spray characteristics at low current where short circuit normally occurs. GMAW-P is spray transfer / or globular - certainly not short circuit.No need to purge SS GMAW pipe unless the heat tint to adjacent base material is undesirable, or a risk to service....Perhaps you need to do you welding technology homework.....use the KISS method and stop adding complexity for the sake of it. Cheers
Reply:Originally Posted by SundownIIIchrispc,Let me get this straight.You come into the thread with a bunch of garbage with no basis in fact.  You don't answer the OP's question about what spray arc transfer is.  You are wrong about pulse allowing you to spray at lower amps (pulsed spray allows welding at lower AVERAGE amps thereby reducing the overall heat in the bead.  The high amps are still required for spray transfer)Then you tell another poster to knock off the BS.What kind of clown are you?Maybe you want to tell ME that I don't know what I'm talking about when it comes to welding stainless steel.Talk about BS.  Your 1.5%O2 mix is just that.  Who the heck mixes that for you?  I think you're confused with a 98%Argon/2%O2 mix which is a good mix for spray transfer on mild steel (hot).
Reply:Originally Posted by sn0border88Sorry, your still wrong.  CO2 has the same things to offer on SS as CS, with is an increase in heat due to the dissociation property.  Considering the OP's limited machine output any extra heat input is going to be of great benefit.  O2 might produce a more constricted and hotter plasma arc, but I fail to see how that has any impact on what he is trying to do.  It does not impart any great deal of heat onto the weld pool (because it is not creating any iron oxides) but simply aids in puddle fluidity and wetting action. The other part your missing is argon's  low thermal conductivity which means that mixes with a high argon content do not transfer heat well. And since CO2 does react with SS, it is a poor choice to have it in large percentages when welding.  Helium is the best of both worlds, great thermal conductivity and low reactivity which is why it is the main gas in any tri-mix.GMAW-P can ABSOLUTELY be short circuit, look at RMD/STT/CMT.  However when talking about pulsed spray transfer the same basic facts still apply.  It uses a high current AND a low current which equate to a lower AVERAGE heat input.Purging to prevent heat tint?  Purging is done to prevent the formation of iron oxides and chromium carbides in the HAZ, heat tint is rarely a consideration for SS welding as it has little effect on the finished metallurgical properties.
Reply:I am now more confused than everTorchmate 2x2 CNC with Flashcut CNC controlsHypertherm Powermax45 Esab ET220i Razorweld 195 MigRazorweld 200ac/dc TigTormach 770, Tormach xstechRazorweld, Vipercut/Vipermig, SSC Foot Pedal Dealer
Reply:Gamble,You don't need to be concerned about spray transfer or pulsed spray (GMAW-P) because your machine is not capable of either.  If you wish to become better informed about the process, then I'd suggest you try the "search" feature.Based on the questions/comments you've put forth, I'd suggest you go to millerwelds.com and click on the "Resources" tab.  If you look, you'll see an offer for their "Student Pack".  It's $25 including shipping.  It contains an excellent Tig Handbook, a GMAW Handbook, a GMAW-P Handbook, and a bunch of other useful information.  Best $25 you'll ever spend in welding.  It will answer your questions about spray transfer as well as pulsed spray.Basically, spray transfer is a high energy/high dispositon welding process that requires voltage and amp levels your machine will not achieve.GMAW-P is a pulsed version of spray transfer, which also requires the high voltage and amps, but also requires a means for the machine to rapidly switch from high range to lo range, thereby allowing the puddle to "freeze".  Puts less AVERAGE heat into the workpiece.For your application, I would recommend that you tack the material up (using tri-mix if at all possible) and take it to someone who can tig it up with a proper back purge.  Until you get a lot more experienced with the use of your machine, I don't think you're going to be happy with the results you achieve with migging it up.You will find some in the industry (Ed Craig for one) who advocate use of 98%Argon/2% CO2 as a covering gas for short arc SS.  Personally, I'm not one of them.  Most of my SS work today is in marine fabrication, but my SS background extends to extensive use of SS in the textile industry.  I've always used a SS tri-mix (90%Helium/7 1/2%Argon/2 1/2% CO2) for short arc welding and have had no reason to change.  I don't use a lot, but I keep a 330 cu ft bottle on hand for when I need it.You got a lot of gobblygook that could confuse anyone from a certain poster.  The fact that the "industry recognized" covering gas for short arc SS (tri-mix) contains 2 1/2% CO2 would kind of dispute many of his "unfounded" claims.Sn0 and I have had our "professional differences" about certain settings (pulsing and amps) for tig welding SS, but the guy knows his business and has provided good advice.  Perhaps if   chrispc would care to post up some "recognized references" for his claims, I'd be more inclined to listen.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:It does seem like we got a little off track there, but these are the discussions that make this place worth checking up on.Anyways, dont just take my word for it.  Here is an important bit from an article in the welding journal.GMAW, Stainless Steel. The most common gases for welding stainless steel are argon/O2 and helium/argon/ CO2 mixes. The argon/O2 blends tend to have about 2 percent oxygen and perform well in spray transfer if some weld discoloration can be tolerated.The trimixes are available in two major types: argon-rich and helium-rich. Helium-rich gases (about 90 percent helium) are used for short-circuit transfer and include a small amount of argon for arc stabilization and a very small amount of CO2 for penetration and cleaning. Argon-rich mixes tend to have about 80 percent argon and about 1 percent to 2 percent CO2 with the remainder helium. Argon-rich mixes traditionally are used for spray transfer, as the high argon content allows spray transfer to occur at relatively low voltages and the helium gives good wetting, flat bead profiles, and good color match.
Reply:So back on topic, can you weld SS with normal mig wire and not SS wire? I seem to be getting the same results no matter what wire.How much gas?Torchmate 2x2 CNC with Flashcut CNC controlsHypertherm Powermax45 Esab ET220i Razorweld 195 MigRazorweld 200ac/dc TigTormach 770, Tormach xstechRazorweld, Vipercut/Vipermig, SSC Foot Pedal Dealer
Reply:Yes, you can, but you won't have the corrosion resistance that a stainless wire has.  On something that will heat cycle, it will show as a rusty weld.  Not necessarily a bad weld, just will look out of place.  Gas setting should be between 15-20.I welded some .062 stainless flat sheet to mild steel angle iron framework.  I used .023, 309L wire & a tri-mix (He/Ar/CO2) at 20.  Welds came out pretty good, once I figured out what all the soot was from.  The soot will wipe right off.  If you can afford it, get the bottle of tri-mix for you 175A welder.  Then you can weld stainless (using a stainless wire) for your buddies to help pay for it.Sn0 & Sundown know their stuff, listen carefully to them.MarkI haven't always been a nurse........Craftsman 12"x36" LatheEnco G-30B MillHobart Handler 175Lincoln WeldandPower 225 AC/DC G-7 CV/CCAdd a Foot Pedal to a Harbor Freight Chicago Electric 165A DC TIG PapaLion's Gate Build