TIG filler issue

[sporkedtospec]

I have corrected myself and changed parameters many times trying to solve this issue. I am TIG'ing .035 4130 tubing (T-joints and similar) and the filler melts/balls up as I try to reach the puddle. I am able to get the initial tacks in around the tube and I can get maybe two good beads 1/8 of the way around the entire joint before the filler begins to melt back. Sometimes I can get it going OK, but cannot maintain a situation where the puddle will accept the filler consistently.
The filler will ball up and usually land in front of the bead and can be wicked back into puddle if persuaded with more heat or torch movement, which is obviously incorrect resulting in lumpy inconsistencies in the bead.

Hopefully the following is enough to provide insight into the situation.
Machine:
Airco Heliwelder.
- High Frequency start.
- WT-20f torch.
- Gas lense.

Settings:
- 1/16" lanthanated tungsten. Fine dressing and wiped with alcohol afterwards.
- .035 and .045 WeldMold 880t filler (same issue with both)
- 48 amps coarse setting (75% to 90% pedal)
- Argon set to around 12.
- Tubing has been prepared with sanding to bare shiny metal inside and out, cleaned with alcohol and care is taken to ensure no contamination prior to welding. Miters are tight.
- Filler is wiped down with alcohol.

Corrective measures:
- Step up to .045 filler.
- Ensure torch angle is steep (even vertical).
- Ensure filler angle is appropriate to torch angle throughout the movement around joint.
- Ensure arc length is tight.
- Ensure puddle is fluid and both shoulders are fully wet. I tested on the ragged edge allowing the egde to keyhole a bit.
- Tested issue on 1/8" flat stock.
- Adjust argon flow range up and down.
- Get the puddle going quick and run the bead super fast.
- Turn up the amps. Turn down the amps.
- Force the filler into the puddle instead of attempting to allow the puddle to draw the filler.
- Reset high-frequency start gap (just in case)

I notice a greenish haze around the filler as it is balling as if invisible heat/gas from the torch is causing it to melt back.

I'm banging my head against the wall. I've taken a couple years off from building with thin-wall tubing and focused mainly on structural (1/8" plus) type material. Not a professional welder, but thought I had the fundamental type issues behind me.
Picture shows at the top of the joint where it becomes a bit lumpy and inconsistent, which is where the problem occured on this particular example.

[prop-doctor]

maybe up your filler to 1/16" =.0625
might take the heat a little better than .045

[con_fuse9]

Looking over everything you posted (hope I didn't miss something)...
I have to wonder if you have the right filler rod. Are you sure its 880T? How can you tell it's a green haze around the filler? You can see the haze through the welding lens? BTW, green typically equals copper, might just be the protective coating on the wire. I don't know what 880 is supposed to have. I would suspect that a chromium based filler wouldn't need all that much copper.

Maybe someone else can comment on what happens if you try to use RG45. Last time I used RG45 (gas welding) it had a pretty thick copper coating on it.

The only time I ever have an issue with the filler wire melting back is when using too small of a filler on aluminum. Step up a size and problem goes away.

On .035 tubing, you shouldn't need more than about 40 Amps anyway. .035 filler should be dead on.

I know 880T is a high strength nickle chromium rod and is very popular with the bicycle builders, but if you can learn anything from the plane builders, ER70-S2 or ER80-D2 instead. I would do fillet welds with the ER70-S2. A little easier to find than 880. Maybe buy a pound and see if that fixes things (cheap trouble shooting).

Just a couple of other comments. 12 cfh is pretty much on the money for a #4 cup up to about #6. I usually put the top of the ball on 15 and call it day. I probably waste more on pre flow and post flow anyway. The thought was that maybe your getting oxygen into the shielding gas an the filler is oxidizing away more than melting. 100% argon of course.

[zapster]

Yep..
As stated 70S-anything is good for what you are doing..
I would go around 50..60 amps but use the pedal..
Stay with the .045..
You will see much improvement..


...zap!

[tourillegal]

I think u might be moving to slow. Ur HAZ is large. I bet the base metal is too hot for the .045. Although the coloring of the beed is good.. I still think that HAZ is atleast double the size it should be. Id say try keeping the rod away when not dipping and get the whole process moving faster.

[David R]

I would try larger filler or feed it from the side instead of in front of the torch. .035 tubing is too small for my fat fingers. :)

Pulse?

David