TIG alumunum: multiple small balls of material on electrode

[keeena]

I had a quick question on how to read this electrode when I was welding 1/8" thick AL: What are all these little balls of junk on the tip? The project I was working on was 6061 which had been weather-exposed for a year. I did sand/scotchbrite and acetone, but I'm guessing that the metal still have been a bit dirty?

The tip was originally prepared at ~30deg and blunted. Machine settings were ~120hz, balance ~75% EN, 140a IIRC. I don't believe I dipped or touched the filler. For ref: i'm not a weldor, just a hack who has some classroom experience with gas & stick welding 15 years ago and then bought a TIG machine 2 months ago...so be gentle

 

[ericc]

I sometimes get the same problem. Is the aluminum bubbling or spitting? First, try on a tiny piece of clean aluminum. You can even try the first time without filler, but this will not have any strength. This is only to test if your tungsten gets dirty. Once you can start a small shiny melted spot without dirty spots, then move on to the filler. Note that this trick doesn't work with DC TIG. There are other tricks to make that work, but you won't get a real puddle. You just have to have faith that it is still down there somewhere. Back to the problem, are you HF starting or lift starting. Don't scratch start on aluminum.

 

[General Zod]

I take it you are using Thoriated tungsten electrodes that you were using on steel?

It can be done, but it's not worth the hassle. Get some 2% Lanthanated, E3/Trimix, CK Layzr, HTP Quad-Mix, or 2% Ceriated. ANYTHING will work better than thoriated, since as you can see, it likes to "cauliflower" and form those little nodules.

Also, if that is a 1/16" diameter tungsten, step-it up to a 3/32" at least when you weld on AC. It heats up more on AC, and the bigger the tungsten the cooler the tip stays and maintains it's point just a wee smidge better.

 

[xr650rRider]

I'd try turning the balance down to 35% or so, at 75% mine would destroy the tungsten.

 

[General Zod]

I'd try turning the balance down to 35% or so, at 75% mine would destroy the tungsten.

Yours might be calibrated with regards to EP. 75% EP will destroy almost any tungsten. His is at 75% EN, which is well within the "normal" range for AC balance.

 

[keeena]

I take it you are using Thoriated tungsten electrodes that you were using on steel?

It can be done, but it's not worth the hassle. Get some 2% Lanthanated, E3/Trimix, CK Layzr, HTP Quad-Mix, or 2% Ceriated. ANYTHING will work better than thoriated, since as you can see, it likes to "cauliflower" and form those little nodules.

Also, if that is a 1/16" diameter tungsten, step-it up to a 3/32" at least when you weld on AC. It heats up more on AC, and the bigger the tungsten the cooler the tip stays and maintains it's point just a wee smidge better.

I didn't realize it, but this one was a Ceriated sample which came with the machine. Because the quality of the freebie Ceriated could be suspect: I'm gonna swap it. I normally use 2% Lanthanated or Layzr for everything I've done so far. I don't use electrodes on different metal types...i keep them separated. That electrode is 3/32.

I have been sharpening the electrodes on a belt sander: something I know isn't ideal and I suppose that could be a minor source of contamination. I do want to get dedicated diamond discs at some point.

I'll try 65-70% EN. My machine has analog knobs w/o any digital readout (my biggest gripe) so it can be hard to pinpoint/repeat the exact setting.

What does that cauliflower behavior mean? Am I on the right track that its dirty base metal / contamination? Or is it caused by something else?

I sometimes get the same problem. Is the aluminum bubbling or spitting?

HF start. And yes, the base metal was complaining. I never touched AL when I learned gas/stick so AL is foreign. I have read up on the basics and generally understand what to look for as far as puddle behavior w/ AL, but not nearly enough experience to know when things are not normal.

 

[General Zod]

I use 2% Ce too, but I doubt it's the tungsten. How were you sharpening the tungsten? To a sharp point? Edit: nevermind, I missed your description in the 1st post. The diameter of the flat spot might not have been enough. Can you show a pic of how it was sharpened before it became like that? AC welding does strange stuff to tungsten sometimes. Dirty base metal liklely won't cause that; it will "spit up" and bits of aluminum can catch onto the tungsten if you happen to have welded over hydrocarbons that end up "burning" under the arc. It has a lot to do with how you sharpen/blunt it, and how quickly you roll into the amps. Are you using a pedal? Torch-mounted on-off switch? Let's see a pic of the base metal. When you say you "sanded it", sanded it how exactly and with what?

 

[G-ManBart]

Ceriated tungstens tend to do that at higher amperages even if you've got everything clean, so I wouldn't suspect contamination too much. You aren't running a super high amperage, but there are other factors like the shape of the tip, balance, post-flow, etc that all come into play.

Still, any sanding/grinding with an abrasive can leave behind particles that will contaminate the surface. If I have to use an abrasive wheel or grinding wheel I follow it with a unitized wheel that will polish the surface so I know it's clean, then wipe with acetone. This is some of why the recommend files and carbide die grinders...they don't leave anything behind that will cause a problem.

I don't see any discoloration on the tungsten, but what sort of post-flow were you using? Usually you'll see discoloration if there isn't enough post-flow, but it could be a combination of post-flow, maybe a touch high EP for the shape of the tip, etc....all of that rolled into one to cause it to happen.

I use a belt sander for sharpening my tungstens, but I make sure to use the same section, and don't use it for anything else. I actually use the middle of the belt to get off major gunk, then shift over to get it pretty clean, and then near the edge for the final shape and polish.

Jody does a video comparing tungstens that show Ceriated developing those nodules here:

Tungsten Electrodes for GTAW

Case Study and Video of Gas Tungsten Arc Welding GTAW Tungsten Electrodes - thoriated vs ceriated vs lanthanated vs pure vs zirconiated

www.weldingtipsandtricks.com