[Grayfox]

Hi, I'm a college student (Limited Funds) with a Lincoln SP 125+ mig welder. I currently have small portable bottles of pure CO2 I use for various things, and I now have a 25# tank that I need to choose a gas to fill with. Although a good portion of my jobs will be mild steel (hence C25), I also plan to weld stainless and maybe even aluminum. I should be welding no thicker than 1/8" or 10 gauge metals, so instead of buying multiple bottles of C25, Trimix and Argon, how feasible is it to fill my tank with pure argon and apply it to ss & aluminum then revert to my pure CO2 tanks for steel? I am well aware of the benefits of C25 and that my puddles might stack up higher with pure Argon, but is it a feasible choice for ss? Thanks for your time.

[delraydella]

Pure argon should work fine for what you plan to do. Sounds like a good plan to me.

[Grayfox]

Ok, the guy at Praxair told me I could do stainless with C25, but I don't buy it. At this point it looks like I might do my mild steel welds with CO2 Paintball canisters, and my stainless steel welds with pure argon, leaving me with the option to do aluminum as well, that way I don't have to buy another tank.

[delraydella]

I've used pure argon to tig weld mild and galvanized steel before and it's worked just fine. It would probably work for mig too, if you didn't feel like switching tanks. I don't know if it's recommended,but all the welds held up fine. But I wasn't doing any critical welds, just a bunch of grinder handles.

[ogorir]

if you're looking to practice at MIG, 75Ar/25CO2 is basically the industry standard. straight CO2 will work, but not that great. I haven't actually tried straight argon myself, but my dad ran out of 75/25 once and hooked up the TIG gas and wasn't too happy with the result. I don't know your actual funding situation, but I just got a year rental on a 125 cube tank for $50 with $33 refills from my local welding supply. their rental fee is flat for all sizes, just something to consider.

I've never welded stainless or alu MIG before, and I wouldn't choose to unless I was doing production work.

[Grayfox]

Yeah I still haven't completely ruled out C25 since it's preferable for the most common jobs, and pure CO2 produces more spatter albeit more penetration, but that would mean I can't weld stainless or aluminum. Although a rental is a good consideration, storage space is also important to me. As for the argon tig results, I'm not sure how comparable that would be to its mig equivalent job. Does anyone know where I can get a small roll of gas-less stainless steel wire?

[ogorir]

tig will be more precise and look better, but take longer.

here's a 2lb spool of 308 on amazon : http://www.amazon.com/US-Forge-Welding- ... B0000DD6IG

I'd check your local welding supply. they should have small spools in stock, or be able to order them.

[Grayfox]

I was referring to a ss wire that is similar to flux core for mild steel in that it doesn't require a shielding gas, thus eliminating the trimix purchase. I just found it, it's 46 bucks a pound!! I was intrigued to see that US Forge recommends C25 for their normal ss wire. I would've thought the high CO2 content in C25 would've posed an unacceptable carbon contamination threat, or possible destruction of the chrome content, but I'm starting to think the reduction in corrosion resistance is minimal when using something like the suggested ER 308L. My choice is now becoming clear.

[kirkepc]

Pure argon is fine.


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[mathewdisoza]

it's fine to use Argon for ss but C25 is best