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SS Soot / Colour - Cooked or Gas Issue?

Posted: Sun Jun 07, 2020 10:49 am
by Srlake
Hi Folks,

It’s been years since I did much TIG welding, and I just picked up a new everlast 161 STH HF TIG machine you weld some 304SS.

I do recall the challenge of getting nice shiny SS weds with controlling shield gas flow and heat, but I’m having a heck of a time more difficulty now than I recall and trying to narrow it down.

Surface prep:
Red scotchbrite + wipe down with isopropyl alcohol.

100% Argon shield *tank is labelled as such, there was some confusion at the store as it was the last tank and it was with a batch of C25.

1/16 2% lanthanated tungsten. Seeing some balling at the tip.

#12 gas lens, argon flow from 15-30 CFH with no change visible

Material is 1/16” 304 SS tube.

Pre flow 1s, post 4s

I’ve run passes anywhere from 40A to 75A with high travel speed. With and without 200Hz Pulse.

In all cases welds are dark grey with a zone of “soot” around the weld.

To narrow it down further I stopped using filler rod (308L) and just ran a bead down the side of the tube and am seeing the same contamination issue.

Any ideas on what to check next?

Re: SS Soot / Colour - Cooked or Gas Issue?

Posted: Sun Jun 07, 2020 6:39 pm
by Coldman
You haven't shown us your welds.
Are you back purging the tube?

Re: SS Soot / Colour - Cooked or Gas Issue?

Posted: Sun Jun 07, 2020 7:02 pm
by TraditionalToolworks
Gas issue, IMO, without even seeing your weld. Your tungsten looks like dark soot also...check hoses/connections/cup/o-rings, something is possibly causing a venturi and sucking air.

Re: SS Soot / Colour - Cooked or Gas Issue?

Posted: Sun Jun 07, 2020 7:38 pm
by Oscar
Show the whole torch. A lot of times people assemble them incorrectly.

Re: SS Soot / Colour - Cooked or Gas Issue?

Posted: Sun Jun 07, 2020 7:51 pm
by LtBadd
I presume you mean the tube has a 1/16" wall? Tell us the diameter, either way welding tubing is definitely more challenging. Start with some plate/flat bar and practice running beads.

You're going to need a few more seconds on the post flow, and when the weld stops don't pull the torch away until the post flow stops.