TIG Welding Thin AL (.020" - .030") revisited

[TWA]

Since my last post on this subject I have still not been able to butt-weld thin 2024-T3 Aluminum to my satisfaction. So I put in a call to the Miller Tech deptartment and had a talk with Don. His advise was excellent and since it was a bit unorthodox, I want to pass this info along to the group.

As I mentioned in earlier posts (August 3, 2004) I was having a hard time keeping the edges of the aluminum from melting away when welding thin edge-to-edge pieces with 1/16" pure tungsten electrode balled on the end in the normal fashion. My machine is a new Syncrowave 180SD. The problem turns out to be the arc was wandering and I was unable to control it's travel. It seemed to be jumping from one side of the butt to the other.

Don's recommendation was to try 2% Thoriated rod...... and it worked to perfection !!! It takes patience and practice but at least I can now butt- weld thin 2024-T3 passibly.

Here are the machine settings

1) Soft Start setting
2) 1/16" AL rod 5356
3) 1/16" - 2% Thoriated rod - (red)...yes this is normally used for steel.
4) 3/8" Gas cup
5) 100% Argon -- 18lbs CFH scale
6) AC @ 18-20 Amps
7) Clean AL material w/Acetone and use SS brushing if necessary
8) Butt the materials to be welded as closely as possible - with my limited experience, I would consider 1/16" or more gap to be excessive.

Preparing the Tungsten ( Yes, it's 2% Thoriated)
Grind to a point ----just as you would do for steel welding.

That's it and I hope this has been of some help.

Tom Warren
Hartwell, GA

[motordoctor]

Now I'm no expert on this but I'm pretty sure that 2024 is not a weldable alloy. At least the books I have say it's not.

"The alloys in the 2xxx series do not have as good corrosion resistance as most other aluminum alloys, and under certain conditions they may be subject to intergranular corrosion. Alloys in the 2xxx series are good when some strength at moderate temperatures is desired. These alloys have limited weldability, but some alloys in this series have superior machinability."
It was always my understanding that you could not make a structurally sound weld in this alloy.
"Most of the wrought grades in the 1xxx, 3xxx, 5xxx, 6xxx and medium strength 7xxx (e.g. 7020) series can be fusion welded using TIG, MIG and oxyfuel processes. The 5xxx series alloys, in particular, have excellent weldability. High strength alloys (e.g. 7010 and 7050) and most of the 2xxx series are not recommended for fusion welding because they are prone to liquation and solidification cracking."

[dyn88]

it was also written once that tungsten couldnt be welded, but with modern techniques and machines(also consistancies in gas, fillers and heat input) many of the once thought unweldable materials are now found to be fusable.