On Fri, 1 Jan 2016 09:06:15 -0800 (PST), Garrett Fulton
wrote:

On Wednesday, December 30, 2015 at 10:11:46 PM UTC-5, wrote:
On Wed, 30 Dec 2015 14:56:12 -0600, "Terry Coombs"
wrote:

wrote:
To All,
So another SS welding job has come my way that would benefit,
timewise, by using MIG instead of TIG. I have a Lincoln SP125 Plus
welder and will be welding 1/16 maximum thickness 304SS for this job.
According to Lincoln my welder should have no problem doing this weld
as long as the right gas mix is used. C25 gas is about 1/3 the price
of Tri-mix with 90% helium. I tried using flow gauges to mix C25 with
pur argon in order to get a Bi-mix ratio of 98% argon, 2% CO2 which
Lincoln recommends, but I wasn't real happy with the appearance of the
welds. This could be because the flow gauges weren't accurate enough,
or I couldn't set then accurately enough, or that the gasses didn't
mix properly (which I doubt), or because I can't weld worth a ****. Or
it could be because the welds would look crappy no matter who did the
welding because 98% argon 2% CO makes crappy looking welds. I could
try the mixing trick with the oxygen but I don't have a flow meter
that is for a low enough flow. So I am thinking about buying a
cylinder of 98% argon, 2% oxygen. Can anyone here give me good advice
about how well the 304 will weld with .030 308lSi wire and 98%A, 2%O
mixed gas?
Thanks,
Eric

Why won't pure argon work ? Is MIG that much different from TIG ? I've
never used SS in my MIG machine , it interests me to know what to expect if
and when I do . I have 2 "flow" guages , but only one is actually a flow
gauge the other is a cheapie .
I did try TIG with C25 once, it wasn't pretty . I think the SS takes up
carbon from the CO2 .
Greetings Terry,
Pure argon won't work for MIG because the SS needs an "active" gas to
get hot enough. When using TIG the heat is of course controlled by the
arc between the tungsten and the work, but with MIG all the heat can
only come from the actual arc between the filler metal and the work. I
have tried pure argon with SS before I knew better and it doesn't work
very well. Tri-mix with 90% helium works well partly because the
helium doesn't carry the heat away as much as other gases. But it
costs a lot and I won't be using it much so I would rather use a
cheaper gas mix.
Cheers,
Eric

Eric,
Just to clarify this: pure argon is okay to use when welding SS with TIG, right? I welded some SS with my Lincoln 175 TIG a few years ago, but can't remember any problems with the weld.
Wiith TIG only pure argon for SS, with MIG mixed gasses.
Eric