304 to mild

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Hi everyone, Looking to get some advice. I've been reading differing information on what I need to have these welds come out good. I am dealing with welding 304 tube, to 304 stainless, then to mild steel at another joint. 110v welder. I use 75/25 for my mig. For the above practice, what gas/wire do I need to use?I know 308 mig can be used for stainless to stainless, with trimix gas being necessary. 309 wire is for stainless to mild, but no mention of gas to be used. Regular mild steel wire and 75/25.Is there a flux core wire I could use with my 75/25, that would allow me to weld stainless to stainless and stainless to mild?Don't really have a full time need for stainless capacity.
Reply:Just so you know, if it's not a critical application you can weld it with standard hardwire (er70s-6 etc.).309 is the recommended filler for 304 to mild. Datasheet says use trimix http://www.weldingwire.com/Images/In...ibrary/309.pdfand...  309LFC-O is a gasless flux cored version of 309 mig wire. http://www.amazon.com/Blue-Demon-309.../dp/B00G5GHKEW (BTW this link this is .035" wire which is too big for a 110v welder)Last edited by MikeGyver; 01-10-2015 at 03:19 AM.Welding/Fab Pics: www.UtahWeld.com
Reply:What is the definition of critical?Will be exposed to pressure and heat, but not a life threatening application. I don't especially want a 304 stainless, just because it was my understanding that if you don't have TIG capability basically don't even try. My supplier though does not have a 404/409 stainless, and the 304 is relatively cost effective, in comparison to them ordering in either of those. I've seen the HTP flux core, and was interested in that option. As it is a small roll. With this could I run a c25 gas for extra care? I was also looking at the dual shield wire (flux and gas) didn't know they even made such a thing. Those are in .045 which my machine may have trouble with and in 33 lb spools. I've talked to the LWS they can get me a large tank of trimix for like $90 and a deposit on the tank. If it was stainless so stainless on everything I may just go that way and use 308. Mild wire seems the better option because I have a full large tank of c25 and use that a lot. Given that I do mild steel work, and steel autobody stuff it may be better so that I don't have to keep switching wires and tanks. Is there a preferred grade that I should look into? Lastly, as far as welding on the stainless. Is there any reason that I couldn't tack weld it at 90*, 90* opposing from that, and continue with tacks until the joint is done? Really appreciate the reply. I've never messed with stainless and am a bit apprehensive. Information out there is quite conflicting and vast. Never knew of Solar Flux B, until I started researching this topic.
Reply:I mean if it's something like welding a leg back on a chair or some other dinky repair that doesn't warrant buying a new wire & gas type. If you're doing a fair amount of weld though then just get the right stuff.What exactly is it you're making. What are the temps and pressures and stresses involved?Welding/Fab Pics: www.UtahWeld.com
Reply:If your machine can pulse you can use 100% Argon when mig welding with 309L solid wire. It is not ideal but it works.
Reply:Originally Posted by taz00If your machine can pulse you can use 100% Argon when mig welding with 309L solid wire. It is not ideal but it works.
Reply:glove,I have used 75/25 and short circuit transfer with 308L wire before to tack some heavier mesh ss wire screens into frames made from 304 angle with good results.   While I don't know exactly what it is you're trying to build  the fact that you only have a 110V welder doesn't sound encouraging as far as you getting any decent results.   Being as you're only going to be able to use short circuit transfer I'd recommend you find the smallest diameter ss hard wire you can get and try it with your 75/25.
Reply:Some quick google-fu yielded me this.   http://www.lincolnelectric.com/en-us...t-welders.aspx
Reply:Yes. It did not work without pulse but it kinda worked with pulse. We had to qualify a procedure when a contractor had to use 100% argon while welding some stainless steel internals in some distilling towers. The job was in another country and the appropriate gas mix was unavailable (99,5% Ar + 0,5% O2 or similar). Welds were acceptable but far from perfect.As I said though it is not ideal and should be used only as a last resort if the proper gas i not available.
Reply:I can understand that.  Some times you just have to make it work as best you can with what you've got available.
Reply:Originally Posted by HT2-4956Some quick google-fu yielded me this.   http://www.lincolnelectric.com/en-us...t-welders.aspx
Reply:Before we go any further, how thick is the steel you need to weld? With the low power of a 110v machine you are really limited to what you can weld, especially if you are wanting to "stack tacks".Airco Ac/Dc 300 HeliwelderMillerMatic 200 (stolen)Miller Maxstar 150STLMiller AEAD200LE (welding and generating power) Hobart MIG
Reply:Originally Posted by SquirmyPugBefore we go any further, how thick is the steel you need to weld? With the low power of a 110v machine you are really limited to what you can weld, especially if you are wanting to "stack tacks".
Reply:With 18 ga. tubing you should have plenty of power, and you may need some practice to avoid burning holes through the tubing. Your "stacks of tacks" may work but won't be as strong as a proper weld.You can use 75/25 with 309L wire for single-pass applications. No need to buy an extra tank if it's just a one-off.JohnA few weldersA lot of hammersA whole lot of C-clamps
Reply:Since I am going to be doing a decent bit of this, I am figuring that I will go ahead and use 309l wire, and trimix gas. Will the trimix cause problems when I am joining stainless to mild?Should I use the 309/trimix at all my stainless to stainless joints and then, switch gas back to 75/25 to weld all the mild steel to the stainless?  Or just run trimix/75/25 for it all?With this, should I be concerned about running Solar FLux B?
Reply:@ glovemeister - for short circuit transfer MIG of SS/duplex to same, recommend trying 98%Ar / 2% CO2 in lieu of {expensive} TriMix.  The blend is on my list of mixes to try."Discovery is to see what everybody else has seen, and to think what nobody else has thought" - Albert Szent-Gyorgyi
Reply:Are you building a turbo manifold? 1st on WeldingWeb to have a scrolling sig! HTP Invertig 400HTP Invertig 221HTP ProPulse 300HTP ProPulse 200 x2HTP ProPulse 220MTSHTP Inverarc 200TLP HTP Microcut 875SC