PDA

View Full Version : 18 gauge SS tig?



Shaf_911
04-24-2011, 10:20 PM
My boss at work had me try tig a few joints the other day. Neither of us could weld it without cooking the beads (too hot, dull gray colored beads, with the penetration side REALLY sugared).

-18 Gauge, guessing 316 SS base metal
-Outside corner joint with an included angle of 135 degrees
-Tight 1/32" gap between the corners to be welded
-1/16" 316L filler, I was dabbing it in the puddle
-1/32" 2% thoriated tungsten
-was trying to travel fairly quickly to limit heat input
-around 35 CFH flow rate of 100% argon gas
-amp dial was set to like 130 or something but I was using peddle anyway.

Couldn't get rid of the gap between corners due to the fit. I didn't think to get a 1/16 tungsten, boss just handed me a 1/32. I questioned the flow rate and boss said it was a good setting so I didn't want to turn it down right in front of him after that. I still think it was too high though. Pulse was available but boss told me you could do it without it.

What would you guys have done? .045/.035 filler? 1/16" tungsten? Turn down CFH? Flick on pulse? Is it even possible to get a clean silvery non-oxidized bead without using pulse on this poorly fit joint? (disregard the sugaring on the penetration side because any type of back purge for this job was completely unnecessary)

sn0border88
04-24-2011, 10:40 PM
If you boss couldnt do it either, then why listen to him? :laugh:

If it were at my work...

3/32 ceriated (because thats what I use for everything)
.045 filler
~60 amps on the dial
Pulser on, probably 2.7-3PPS, 40Peak, 25Background
Flow 15-20 CFH


What amperage were you trying to do this at?

Is it possible? Absolutely, but it takes skill.

gordfraser
04-24-2011, 11:09 PM
i was doing some 24 gauge 316 recently and and gap between the two parts turned it into a royal pain.
the top layer would always want to burn back. id run a 1" bead at the most and then go weld aomewhere else. then when it was cool id tap the joint closed if required and go again.

think i used 20CFH , 1/16" tung and 1/16 rod at 60amps or so with a pedal. Id pulse the pedal once id get the puddle and move forward a bit then pulse again.

and a clean glass in the hood.

B_C
04-27-2011, 07:01 PM
For me to want to screw with stainless sheet metal AT ALL the fit needs to be intimate, BUT if it's your boss telling you what to do and there are gaps (I assume your sanding when done?) I would get a piece of 1/16 filler and leave it in the joint and carefully fuse the joint taking care not to burn the parent metal and concentrate the heat on the filler filling the gap as you go letting it cool every 1/2 in. or so till you get the joint welded then sand the profile back......Not much else you can do with thin sheet metal and gaps.....Then go kick the guys azz that bent it up for you....works for me....:D

Pro-Fab
04-27-2011, 07:24 PM
With 18 ga. you should be able to tack a spot, then tap it with a body hammer while hot to close up the gap. How long were the joints? If you close up the gaps and have a small tack every 1/2", you can weld up an outside corner without fill rod. Pulse will help, but without it you should be running under 40 amps. I am sure everyone will agree that your shielding gas flow rate was waaay too high.

wijo0131
04-27-2011, 08:26 PM
I would use .045 filler, a gas lens with a #6 cup, and flow around 15-20. From my experience, using a regular collet body on thin stainless doesn't work very good. I would also try, if it's practical, using a copper, or aluminum, back up/heat sink.

Baila La Pinza
04-28-2011, 05:14 AM
Personally, Given the choice I would have welded it vert down, or if I had to do it flat then preferably with a copper backing strip. I think shiney silver beads would be a big ask, should be able to get it at least salmon/purple colour though. I normally use a 3/32 tungsten for everything, but 1/16 would be fine too (maybe better in some people's opinion), and 1mm filler rod layed in the joint. Gas coverage is always an issue with corner joints, would definately use a gas lense, the bigger the better.

jethro
05-02-2011, 04:09 AM
My vote goes to using a very short arc- very small rod maybe mig wire - and slow your travel speed down -way down and use a very low current to go with that slow travel speed. Just enough current
to make the puddle slightly bigger than the mig wire. The other ideas sounded good too.
Tack often and massage gap shut - lay wire into crack. (just did that last nite)
Also use the smallest electrode you have - like .040
but on the other hand I'm not really good at doing stainless like you would like on a countertop
where the joint is perfectly smooth and ripple free-
The laywire technique might help cosmetics if it is practical to do.
But that doesn't solve the gappy open joints though. You need to invent a special pair of
pliers which can grab both sides of the joint and draw them together while you tack. Like
butterfly bandages do for an open gaping wound that has to be closed cleanly .
Tim