Subject: Re: mig info needed

From: [email-masked] (James W. Swonger)
Date: 3 Nov 1995 18:36:51 GMT

Three gasses are commonly used for steel MIG welding: Argon, CO2, or 
75/25% mix.  Argon makes the weld "sit up" higher, i.e. less penetration 
& slump. Probably OK for sheet metal, not good for heavy work. CO2 
produces the most penetrating weld, bad for sheet metal but ideal for big 
iron. The standard 75/25 is a compromise.

 I don't think 75/25 is suitable for aluminum. When I've tried it, I get a 
dirty weld with poor appearance, lots of residue. I think the CO2 decomposes
and leaves a lot of Al2O3 in the weld, plus loose carbon.
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From: [email-masked] (CROCUSDES)
Date: 3 Nov 1995 20:08:49 -0500

You can get away with using argon on steel but the welds are hardened and
it's tough 
on your carbide bits if you are surfacing the fillets etc.  If you don't
want two separate
tanks then you might consider having flux  core wire for your steel work
if you don't
mind the fumes.  Chris Ray