In article , Jon Elson
wrote:

Ernie Leimkuhler wrote:
In article , Jon Elson
wrote:


Hello, all,

I'm still learning the fine art of TIG welding, but making
progress. I'm doing the first real project, a table for
a 24 x 36" surface plate. I'm using 2.5" OD steel pipe,
"electric resistance welded, drawn over mandrel" and
steel angle. The pipe looks almost like it was chromed,
but did have a hint of rust on it, but I have no clue as
to alloy. The angle I'm using is hot rolled, but other than
that, no clue to alloy, either. I'm having a HELL of a time
keeping the electrode clean. It gets something, I assume steel
contamination all over it, heavy up to the cup, and light all
the way up to the collet, in just a few minutes of welding.



Are you trying to weld through the oxides on the hot rolled angle?
You can't.
You have to grind off any oxides.
TIG requires clean metal.
No oxides, paint, rust, oil, plating, or dirt.


Right, I know that. I do grind the area within about 1/2" of the
weld. On the pipe, it is so smooth and clean, I tried a wire wheel
and just using solvent, and don't see any difference.




Oh, so you are trying to use pure tungstens on DCEN.
No wonder your arc is going nuts.
Use Thoriated tungstens at least, but even better are Lanthanted
tungstens.
They work on AC or DCEN.

Thoriated work on DCEN, but are bad on AC.
Pures just suck, but they suck even worse on DCEN.

OK, thanks. I go bad advice from the guy at the welding store and
haven't gotten back for some different electrodes.


Get yourself some Lanthanted tungstens and never worry about what
tungsten you are using ever again.

Thanks! I have a pack of Thoriated elecrodes somewhere around here, but
I'll get some Lanthanated ones as soon as I can.

But, in this particular work, I get contamination all the way up
the electrode. Something in there, I'm guessing the hot rolled, is
making sparks - just like from a grinder. I'm pretty sure it isn't the
pipe or the filler metal (ER70S). Is this a problem with insufficient
shielding gas, or is this particular material just going to spit sparks?


Check your system for leaks.
Get yourself a small spray bottle, fill it with water and 1 tablespoon
of dish soap.
Spritz the soapy water on all your gas connections to find leaks.
Just look for the bubbles.

I'm pretty sure there are no leaks, now. Of course, the welder was a BIG
"leak" as it left the gas valve open all the time. That is now fixed.

Thanks much for all the help! I am actually getting good welds now in
this mixed steel job, and really getting a good feel for controlling the
arc and melt pool.

Jon



You should try some stainless steel filler rod on your steel welds to
see if they settle down.
Stainless can deal with more contaminated materiel.
The nickle and chrome help it flow in nicely.