Hybrid Tungsten?

[jakeru]

John, I haven't really done enough testing to really be confident I have chosen a "favorite" yet, but I can certainly tell you what I have been and currently am doing.

I started off using 1.5% lanthanated for everything. I skipped pure, (never heard anything good about it,) and skipped thoriated, (figured I'd not worry about any radioactive safety hazards IE: grinding dust) and just focused on the newer, safer, better products available.

I generally do all my welding (both AC and DC) with a solid (not melted / balled) tungsten tip. I usually don't go too high on EP% balance (20%-35% or so) in A/C mode, to keep the torch cool and the tip from balling, and often find benefit in the focused heat and deeper penetration, and narrower heat affected zone. It works well mechanically, welding as thick as 3/8"+ aluminum with just a 3/32" tungsten @ 200 amps, 20-25% AC balance, with lots of duty cycle. In fact I've got some 1/8" tungstens, but very seldom use them.

I am set up with .040", 1/16", 3/32", and 1/8" tungstens in 1.5% lanthanated, but am gradually switching them out with 2% lanthanated as I use them up. I am not sure I can tell any difference yet between the two, but am hoping for an improvement in the tip lasting longer without forming "multiple protrusions". I just live with the expected tip degradation, and expect to swap on a sharp one when I get to a stopping point, or when its needed. I keep the grinder nearby and try to keep tips sharp and ready to go on important jobs. With more time I should be able to tell if 1.5 - 2% lanthanated makes any difference.

I tested the zirconiated and found stark differences to the lanthanted, as I mentioned in previous post. I have a stick of ceriated I got to try and have used it before but not much, so far it seems pretty similar to lanthanated. Supposedly one is easier starting when they are both freshly ground, and the other is easier starting after its been used. At least in theory.

I did do some experimentation with using higher EP%, and welding in A/C mode with a balled (molten while welding) tip, but its kind of a complicated topic. To make a long story short - balled tip = can't concentrate the heat. You can weld nice diffused beads though, which mask a lot of torch and filler rod jitters / inconsistencies which can make a really nice "stack of dimes" aesthetic.

If you're doing build-up operation, the wide, diffused heat setting is often advantageous. There may be aesthetic reasons as well to ball the tip or otherwise try to diffuse the heat. But if you're joining metals, the deep penetrating, narrow focused heat setting is usually best. Sometimes focused heat can be good for build-up also. The arc distance can have a big impact on heat focus vs. diffusion as well.

If I had a watercooled TIG torch, and a more powerful machine, I'd probably be inclined to use the balled tip, higher EP%, more diffused heat setting more often than I have. But I've just got 200 amps and an aircooled torch. The focused heat setting expands its aluminum thickness capacity substantially which is really useful for me.

Here are some of the test beads I did when I was playing with zirconiated vs lanthanated. I made a lot more of them, (some really nice looking) that I covered up by running beads either next to them or on top of them, or on the back side of by the way. I didn't do these to take pictures of I did it to learn, but you can see there is probably a 4x difference in bead width between the widest to the narrowest bead. (It is all 1/16" thick material and I was using 1/16" tungstens.) It was a lot of fun and I look forward to putting some "wide aesthetic" beads on aluminum to work here soon.

The balled tip might have advantages with more readily vaporizing (burning off) most contamination.

I do a variety of welding jobs as part of a side welding business I've got. It tends to be a lot of repair work, but also a little bit of new fabrication work so it's a nice mix, focused on primarily TIG welding. It's a lot of fun and very challenging. There are flakes out there I have to deal with in the course of doing business, but I also get some really nice people to do business with. I especially value repeat customers who don't quibble with the bill.

[Ray]

so your saying with HF start its inevitable ... i would have to disagree with you on that
with scratch start yes but not HF start

One would think so, but actually there is transfer of material during Hf start, if you’ve noticed what looks like little comet trails or a meteor storm when starting is actually tungsten being ripped from the electrode and it ends up in the weld and show on an x-ray as tiny bright spots on the film. Lift start is actually the cleanest start. That is why it’s an option on some of our high end welders (Lift Start).
My experience has been the inspectors are more worried about inclusions in the weld more so than microscopic contamination, what we used to call porosity. But perhaps someone currently working on boilers and such give us some current procedures.
It looks like the NRC is specifying submerged arc for reactor vessels now. But still Tig on high pressure pipe.