How come MIG worked on stainless steel?

[Jon K]

So I built my turbo setup and wanted to add a little bracing. We found 1/4" steel flat bar and started migging up a brace. Then, for ****s, we took the MIG to a piece of stainless I had - it welds! We're using 75/25 argon/co2 with "allow" filler wire (thats all it said on the spool i dont remember the #s, but its a brass/copper looking wire) and it fused mild steel to stainless VERY well. Whats the deal?

[MicroZone]

Well, because essentially SS is still just steel with additives.

[Rojodiablo]

Originally Posted by Jon K

So I built my turbo setup and wanted to add a little bracing. We found 1/4" steel flat bar and started migging up a brace. Then, for ****s, we took the MIG to a piece of stainless I had - it welds! We're using 75/25 argon/co2 with "allow" filler wire (thats all it said on the spool i dont remember the #s, but its a brass/copper looking wire) and it fused mild steel to stainless VERY well. Whats the deal?

SS is maybe the most forgiving material there is to weld to. It accepts all processes, and it does everything a builder could want: It is corrosion resistant, bends well, can be of spring grade, can be polished, and bonds to many different grades of steel. It is great stuff. That is why it costs 2 times as much as mild steel!!!!

[Jon K]

Man and to think I have been TIG'ing it thinking I HAD to tig it... The MIG works so much better for what I am doing.

[smithboy]

if you mix it with mild steel, it will start to rust pretty quickly...that's the only real problem I have run into. I have even stick welded mild to stainless using 6011 on an old ac225 (at least I think it was 6011) when just messing around making some yard art.

[fun4now.]

yep , rust is the only thing you got to worry about now, without the proper filler and a good back gas you will lose the propertys of the SS and its going to rust, you could also have some structual isues depending on how you go about it. when TIGing SS you need to hold the post flow longer wile it cools to keep it as it should be your mig is not going to give it the needed post flow for a good cure. if its not a critical application and rust is no big deal you should be fine.

[littlefuzz]

I made a chess board out of ss and mild pieces before. Cut them out in 1 1/4" sq. pcs. tacked them togather. That was a heavy chess board. Looked nice. I polished the ss and taped it off and sprayed the mild black.

[onefastduc]

I am a newbie getting ready to teach myself to weld and I'm curious about MIG and SS too. So if I use SS wire and SS stock I can weld with 75/25 gas? I thought a different mix is required for SS. Also, is there a flux core wire specifically for SS?

Thanks,
Chris

[zapster]

Originally Posted by littlefuzz

I made a chess board out of ss and mild pieces before. Cut them out in 1 1/4" sq. pcs. tacked them togather. That was a heavy chess board. Looked nice. I polished the ss and taped it off and sprayed the mild black.

that sounds cool

post a pic?

...zap!

[littlefuzz]

Regretfully I never took any pics of the board and I don't have it anymore. The square on it were 1 1/4" sq. so that a shot glass would be the chess pieces . I had to get rid of it, I ain't that good at chess and I was becoming an alcoholic .

[onefastduc]

Back on topic, can someone help me?

Thanks,
Chris

Originally Posted by onefastduc

I am a newbie getting ready to teach myself to weld and I'm curious about MIG and SS too. So if I use SS wire and SS stock I can weld with 75/25 gas? I thought a different mix is required for SS. Also, is there a flux core wire specifically for SS?

Thanks,
Chris

[Treb5]

I would also like to see an opinion on the SS question with C25. Thanks

[TiFreak]

300 series stainless is an iron based alloy with high amounts of chromium and nickel and 304 is 18cr 8ni 74fe so that is why mild steel and stainless will weld together

[zapster]

Originally Posted by Treb5

I would also like to see an opinion on the SS question with C25. Thanks

nmy opinion is straight argon...

...zap!

[pulser]

Dudes,
ya'll are getting a little carried away with mixing plain steel and stainless steel! Yes you can do it, but remember why someone invented metallurgy?
It's like Frankenstein, it could turn mean on you.

As some of you have said in other posts, 309 SS is generally the filler metal used for joining steel and stainless steel, because it's alloy content allows the weld mixture to remain austenitic. Just mixing 304, 316, or 308 with steel will likely result in hard brittle crack sensitive martensitic weld. This is OK for a chess board, but not great for your trailer hitch.

Regarding the gas for stainless MIG, too much CO2 in the mix (75 Ar-25 CO2) will result in an increase in the weld carbon content. Again for you application you may not care. But why do you think they go to the trouble of making 304L, 316L, 308L, etc., with extra low carbon content? It's to help prevent chromium carbide precipitation that robs Cr from the matrix and totally hoses up the corrosion resistance.

Not too sure about short arc MIG, but with spray or pulsed spray, use 99/1 or 98/2 Ar/O2, or CO2 and Ar up to 5%.

[BBchevy396]

Thank you Pulser............... Someone finally adressed the structural/Martensitic/crack prone issue of welding 300 series SS with steel filler wire............. It will fuse, but it will crack, eventually............. thanks for the heads up!

[onefastduc]

Pulser, Zap, thank you. What I hear from you is that it is possible to weld SS using SS wire on a MIG using C25 mix but the weld and area around the weld could lose its corrosion resistant properties. Thanks again.

Chris

[halbritt]

There are a few different gases that can be used on stainless for optimal results with wire fed processes:

- C25 can be used with stainless FCAW wire. The flux prevents carbon absorption from the shielding gas. Unfortunately, the wire is very expensive and not really available in small quantities.

- 98/2 Argon O2 and 99/1 Argon O2 mixtures can be used for spray transfer on stainless.

- Tri-mix (argon/helium/CO2) is generally recommended for short-circuit on stainless. Different gas suppliers have different blends. Alternatively, C5-C8 can also be used for short-circuit transfer. Unfortunately, these gas blends generally aren't available in anything less than a 250CF cylinder. There are other tri-mix blends as well for spray, pulse, and short-circuit including argon/N2/CO2 and Argon/H2/CO2. I'm eager to try one of the H2 blends, which supposedly gives excellent appearance and corrosion resistant properties. Unless I can get a small quantity, I don't see it happening.

- Straight argon could probably be used in a pinch with a little more heat and close attention to the bead shape. I've not seen anything written about this, so this is entirely my theory, but based on what I understand, it should work ok and still preserve the corrosion resistant properties of the stainless. The color might be a little off and the bead might not wet out as well as it otherwise would. This could likely be compensated for with inductance and/or torch manipulation. I don't suppose that this really qualifies as optimal, but it is an option for those that don't want to purchase a large quantity of specialty gas.

[zapster]

- Straight argon could probably be used in a pinch with a little more heat and close attention to the bead shape. I've not seen anything written about this, so this is entirely my theory, but based on what I understand, it should work ok and still preserve the corrosion resistant properties of the stainless. The color might be a little off and the bead might not wet out as well as it otherwise would. This could likely be compensated for with inductance and/or torch manipulation. I don't suppose that this really qualifies as optimal, but it is an option for those that don't want to purchase a large quantity of specialty gas.
__________________
-Heath


way to go..

i only posted because i use straight argon with a tig...

tig..mig same thing but diffrent...

...zap!

[halbritt]

The problem that I see is that most hobbiest types that would want to do stainless would only want to do so rarely and the cost of entry is pretty high. The cheapest generic stainless FCAW wire I've been able to find that works with C25 is about $200 for a 10Lb spool. Solid wire can be had pretty inexpensively in 2Lb spools for about $15-$30, but then the gas is prohibitively expensive. Few hobbiest have 250CF cylinders lying around (unless they're nutjobs like myself) and even fewer would want to commit a cylinder that large for use with a specialty gas that would take years to use up. Again, the minimum cost of entry is going to be several hundred dollars.

So, I theorize that a solution to this dilemma would be to use straight argon, which is available in cylinder sizes that I suspect is more common for the typical hobbiest, that is, 20, 40, and 80CF. I believe it was about $20 or less the last time I got an argon fill in my 40CF cylinder. If a person only has one cylinder with C25, they could swap it for straight argon, and then swap it back. The total cost for this solution would be about $35-$50 for some argon and a 2Lb spool of wire to do some stainless welding while preserving the important characteristics of stainless such as corrosion resistance.

The difference between using straight argon for TIG and straight argon for MIG has everything to do with the rate at which filler is added to the pool. Obviously, with TIG, one adds only as much as is needed. With MIG it goes in as fast as it goes in. The additional components in tri-mix and the spray mixes are there to increase the amount of heat in the weld bead and improve bead wetting. Though it's a compromise, I guess that this can be accounted for with a bit slower wire-speed, a bit more voltage, some inductance, and good torch manipulation. I believe the worst thing that would happen would be a bead profile that is too convex, which could be corrected with the judicious use of a grinder (with a stainless grinding wheel) if appearance is even a factor.

I'd be eager to see comments on this from folks that have actually done a lot of stainless. I've got a roll of ER308L lying around, I suppose I should try this out myself and report the results.

[Rojodiablo]

Originally Posted by halbritt

The problem that I see is that most hobbiest types that would want to do stainless would only want to do so rarely and the cost of entry is pretty high. The cheapest generic stainless FCAW wire I've been able to find that works with C25 is about $200 for a 10Lb spool. Solid wire can be had pretty inexpensively in 2Lb spools for about $15-$30, but then the gas is prohibitively expensive. Few hobbiest have 250CF cylinders lying around (unless they're nutjobs like myself) and even fewer would want to commit a cylinder that large for use with a specialty gas that would take years to use up. Again, the minimum cost of entry is going to be several hundred dollars.

So, I theorize that a solution to this dilemma would be to use straight argon, which is available in cylinder sizes that I suspect is more common for the typical hobbiest, that is, 20, 40, and 80CF. I believe it was about $20 or less the last time I got an argon fill in my 40CF cylinder. If a person only has one cylinder with C25, they could swap it for straight argon, and then swap it back. The total cost for this solution would be about $35-$50 for some argon and a 2Lb spool of wire to do some stainless welding while preserving the important characteristics of stainless such as corrosion resistance.

The difference between using straight argon for TIG and straight argon for MIG has everything to do with the rate at which filler is added to the pool. Obviously, with TIG, one adds only as much as is needed. With MIG it goes in as fast as it goes in. The additional components in tri-mix and the spray mixes are there to increase the amount of heat in the weld bead and improve bead wetting. Though it's a compromise, I guess that this can be accounted for with a bit slower wire-speed, a bit more voltage, some inductance, and good torch manipulation. I believe the worst thing that would happen would be a bead profile that is too convex, which could be corrected with the judicious use of a grinder (with a stainless grinding wheel) if appearance is even a factor.

I'd be eager to see comments on this from folks that have actually done a lot of stainless. I've got a roll of ER308L lying around, I suppose I should try this out myself and report the results.

I find this to be very true. I build truck racks sometimes. We use a mix of SS parts, like cleats and such. We weld them straight to the 1010 tube for the rack. NEVER an issue. I use the standard 75/25 gas. The cleats/ etc.are usually 3/8" rod, the tube is either .090 or .120 steel. We polish the SS, paint the rest. As for mig welding SS, I use .023 wire. The .030 "humps up" too much. Either with 100% argon, or 75/25 gas. I like the welds smooth if I can have them, and the SS just stands up taller. Grinder can fix this. With heavy SS, I imagine .030 or .035 is fine. And for spray , I imagine .035 is the minimum. My welders don't run that hot.And, I don't do SS over say 1/4" thick on small parts. I fing that SS is VERY forgiving, and bonds well to regular steel. For tig, when it counts, I just use 309 rod, and regardless, I polish all welds clean with SS parts. People just expect it with what we make.

[littlefuzz]

Come to think of it a few years ago I built some paint mixing pots (around 50 gal.) for a company. I used SS wire .035 and straight argon. It welded very good with the heat cranked on an old Linde welder.