MIG welding stainless

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Hello, Im pretty new to mig and have been doing some mild steel welding with 75/25 blend and im going to try stainless and aluminum. I will purchase a bottle for aluminum (100% ARGON). My question is Ive read that stainless should be welded using tri gas but also read that it can be done with 75/25 mix (argon/co2) but causes corosion problems on multi passes. my questions are is can anyone confirm this? Does this effect the strenght and apprerence (other then rust in th future) and I read that on stainless a heat sink should be used, will this stop the bluing or just reduce it? Thanks in advance.Last edited by franklarabie; 03-29-2009 at 02:15 AM.
Reply:There's a lengthy discussion of mig welding stainless steel on the Hobart board.  I'd suggest going there and reading it.Not going into another lengthy discussion on the effects of C25 on SS.  If you do a search here, you'll get different points of view.Personally, I don't use C25 on stainless. Period.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:Argon works fine. It is whats used on ss pipe.
Reply:thanks sundownIII for the heads up, I couldnt find much on this site so i took your recomendation and went over to the hobart site and it answered my questions thanks very much WHughes what the effect of straight argon? corosion?
Reply:Originally Posted by WHughesArgon works fine. It is whats used on ss pipe.
Reply:WHughes,Yeah, I'd really be interested in where you get your information.You ever MIG welded stainless steel?100% Argon is used for TIG welding pipe.  Not mig.You've made a statement as FACT.  Now we need to see some backup data.I've been doing SS marine repairs for longer than I care to mention.  I'm not crazy about keeping a 330 cu. ft. bottle of Tri-Mix sitting around for however little I need it (most SS work is done with tig), but when needed, it's the only gas I'll use on SS.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:You are correct, Sundown, it is used for TIG. You may have to check about MIG. Maybe tri mix is the best way to go.
Reply:Here is a gas chart. It may help. Attached Images
Reply:For stainless GMAW, generally you would use either a tri-mix (for short-circuit transfer mode) or 99-1 or 98-2 argon-O2 (for spray transfer mode).Plain argon might be used for back-purge, but NOT for the arc shielding gas in GMAW.Single-pass GMAW might be done with a low-percentage (as in low single-digits) CO2-argon blend, but you run the risk of carbon pick-up from the CO2 into the weld bead lowering the corrosion resistance of the weld.  And corrosion resistance is one of the reasons to generally use stainless steel in the first place.source: Lincoln Stainless Welding Guide, Document c64000    The best laid schemes ... Gang oft agley ...
Reply:I thought the correct term was MAG when welding on SS
Reply:Speen,Europe uses the term "MAG".US pretty much uses the term MIG, although the more correct term is GMAW which covers both MIG and MAG. Canada just says "Eh?"      The best laid schemes ... Gang oft agley ...
Reply:Thanks.  I thought that sounded a bit too good to be true.Let me ask another question.  What is the most economical way for me to weld stainless given my current equipment?  (Keep in mind I only want to do this occasionally.)Flux-cored, gas shielded stainless wire?------------------------------Lincoln 175HDLincoln AC/DC225Smith O/A
Reply:cny,If your two machines are a 175 mig and an AC/DC stick machine, you could :- get stainless wire of the appropriate alloy and the correct shield gas (probably tri-mix) and GMAW the stainless parts;- get some stainless SMAW (aka stick) electrodes of the appropriate alloy and stick weld them together.The flux-core gas shielded stainless wires seem to come on bigger spools (12 inch diameter 25 lb spools) than will fit in your 175 machine and seem to be generally a bigger diameter wire than that machine can really run anyway (volts and amps and WFS).  The best laid schemes ... Gang oft agley ...
Reply:I am pretty new to welding. I am building a SS clam steamer for my dad and I have rum into some snags. I am using 18 gauge 304 SS. I am building this at my buddy's house so my dad does not see it. I am using a smaller Lincoln Mig using stainless solid core and TRI-mix gas. I can get the outsid corners looking pretty good because I can grind them with ease. I have been running into overheating/ warping the steel which I have been combating by doing short welds. So the main question is HOW DO I GET THE INSIDE CORNERS TO LOOK LIKE A PRO DID THEM? Any special grinding wheels, lead free solder?ThanksEd
Reply:In answer to your question.If you want those inside corners to look like a PRO did them, get a PRO to tig weld them for you.18ga is pretty light material.  As you've already found, controlling the heat is a major problem with the mig you're using.  Stainless is difficult to weld (without warping) because of the extremely low heat conductivity of the material.  Much better controlled with tig.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:So to weld a 3" exhaust tub (16-guage) would argon be a bad shielding gas? (straight argon).That is my plan.I heard you can use a tri-mix with some helium maybe but then I was told that was used to heat up the metal, and it really isn't needed for such thin SS.I was told that 98/2 argon carbon will work but that the puddle will not have a lot of surface tension so welding anything but flat will be hard.  So straight argon was recommended.
Reply:It's 98/2 argon/oxygen, not carbon dioxide...For your 3" exhaust tube, if  you're tigging it, then yes, argon is the correct gas.   If you're migging it, then no, argon is not the correct gas.  Use 98/2 argon/oxygen, or a tri-mix, for mig on stainless.MM350P/Python/Q300MM175/Q300DialarcHFHTP MIG200PowCon300SMHypertherm380ThermalArc185Purox oaF350CrewCab4x4LoadNGo utilitybedBobcat250XMT304/Optima/SpoolmaticSuitcase12RC/Q300Suitcase8RC/Q400Passport/Q300Smith op
Reply:Found this thread interesting.Been welding SS for years , 95% of it is Tig but the occasional Mig . Have only ever used 100 He with no dramas. Occasionally will use 50/50 He Ar in Tig.In Mig its only ever single pass.What are the potential problems with straight Ar Mig SS ?BrettA good guess is better than a bad measurement
Reply:Originally Posted by WHughesHere is a gas chart. It may help.
Reply:I tried to find stainless fluxcore wire locally and couldn't find any.  I had to do a job in stainless on site, so I bought stainless stick electrodes and welded with those.   It was a learning experience but came out pretty good considering I had never stick welded stainless before in my life.   Now I have dc tig on the truck so I probly wont mess with stainless stick welding much anymore, unless it's really windy or something.MM350P/Python/Q300MM175/Q300DialarcHFHTP MIG200PowCon300SMHypertherm380ThermalArc185Purox oaF350CrewCab4x4LoadNGo utilitybedBobcat250XMT304/Optima/SpoolmaticSuitcase12RC/Q300Suitcase8RC/Q400Passport/Q300Smith op
Reply:The 98%Argon/2%O2 mix that's being referred to is used for mig welding stainless using "SPRAY TRANSFER".  Not a good gas for short circuit transfer.When you take into account the cost of the base material (stainless steel), the cost of a small bottle (40 cu ft or so for the home hobbiest) is really not all that expensive.  If the project doesn't require the durability factor of stainless (yes stainless will rust also, it just rusts less) then why spend the money on stainless base material.  To weld stainless with C25 (adds carbon to the weld) results in a weld bead which is not a whole lot more impervious to the elements than mild steel.  Plus, when it's been welded with C25, a "proper" stainless steel repair is much more difficult.  (Ask me how I 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:Hello,   Just jumping in here I have never posted to a thread or anything like this but it looks like there is a lot of smart people in here. I am sorry my question is not about mig welding but it is about stainless steel.  I need to know if welding 316ss to cast stainless is a good or bad ideal.thank you for any info you may have or any articles.
Reply:HOT,It all depends on -what- the 316 is being welded to.Cast stainless still encompasses a pretty wide range of materials, some of which are weldable and some which are not.So the answer is, it depends.    The best laid schemes ... Gang oft agley ...
Reply:Originally Posted by mudbugoneDon't want to step on toes here,but ..SS Flux Core wire comes in small rolls too...not just big rolls. It's very expensive,but as the chart posted above shows under (FCAW) it can be used with 3 different gases or without gas(though I doubt the results would be satisfactory w/o gas).I've got a small 2# roll of it somewhere that I bought on salefrom C/H,but haven't had a need to use it yet.It can be ordered at the Ready-Welder site in both the small & larger spools(If you can't find it listed ask me,I'll find it for you)...I think even Campbell/Hausfeld had the small spools last fall.I've never used the stuff so I can't swear to it's cosmetic finish,but if all you have to do is an occasional bit of SS with a mig...then it's easier/cheaper than an extra gas bottle of tri-mix. It probably won't be as slick as a Tig joint,but if you don't do much SS it might be good enough to fix some items.SS flux core seems to be used mainly in production work since I've only heard 2-3 people talk about using it at all and I think their use was in production work. Seems most repairs are done with TIG on SS not MIG.I heard SSFC mentioned a lot,but nobody seemed to know much about it,so I spent a lot of time on the computer last year researching it. I still didn't turn up much info on it,but I did find some sources to purchase it in small spools.---Ready-Welder Stock # 5507 1# spool SSFC wire the owner can also get 10# & 25# spools on special order.
Reply:Like I said it's expensive!!!  (It usually costs less per # in larger spools) I had to chuckle at your shock...I felt the same when I first heard the price.I think I paid $40 for a 2# spool on Ebay,but it doesn't come up too often. I saw a 10# spool the other day for $50 plus S&H,but didn't need it. I ought to pull it out and give it a try just to see how it welds. I've got a large SS sink that needed a repair which is what I bought it for. I just haven't pulled the sink out from behind stuff to mess with it. I knew 1# was $50+ and just bought the 2# when I got it for a lot less. Check your private messages cnywelderLast edited by mudbugone; 04-09-2009 at 12:44 AM.If anyone is interested in some of this SS flux core wire.... I found a 10# spool on ebay with a starting bid of $50 +S&H  Ebay item #220391012549That's a pretty good price on a 10# spool.... I don't need anymore and I've already maxed out my toy money for a while anyway.Just in case anyone wants to try it out.
Reply:oops just reread your postLast edited by IamVince; 04-10-2009 at 04:36 AM.