Welding aluminum with DC

I think what you're after by your description is TIG, or tungsten inert gas welding.. I've welded similar material using Argon and AC current with a high frequency, high voltage, 'igniter' superimposed on the welding current.. TIG welders commonly have this high frequency component built into them.. Add on units are available for most common stick welders..

It is also possible to use AC, a tungsten electrode, ignore the igniter, and start the arc by scratching, but it takes more skill.. You'll still need to shield the weld with inert gas however, as aluminum oxide melts at a much higher temperature than the base material, quite unlike ferric material..

Alternatively, you can stick weld aluminum using DC with the appropriate coated electrode, but check with the manufacturer(s) for recommended operating current.. 1/8 is about a thin as you commonly can weld aluminum with this method..

Needless to say, MIG welders also would serve you well.. MIG and TIG are very similar, and vary mostly in the method of applying the filler material..

Diana

I am looking to do it with a TIG welder and DC current. My welder does not do AC, yet, though it has high frequency.

this method..

I already have a TIG welder, I am looking for suggestions on how to start welding aluminum with DC and whether I can get away with argon.

I find welding aluminum with TIG to be easier than stick welding mild steel.. Welding aluminum often requires no filler, depending on joint separation and angle.. Keep in mind however that some alloys of aluminum are more difficult to weld than soft aluminum.. Particularly those with high silicon content..

Going by memory, I used around 30 to 50 amps for 1/8 material, depending on speed, in soft aluminum.. Pretty low current compared to mild steel.. DC works fine, and reverse polarity provided more heat to the material.. Argon was the gas of choice, but helium also works.. Gas flow was only about 10 Ft3 per hour, depending on cup size..

Be aware that TIG/MIG welding with inert gas produces considerably more ultra violet than normal stick welding of steel.. It's easy to get a bad burn on unprotected skin very quickly with TIG, even at relatively low currents..

Naturally if you're using a filler, make sure it's close to the same composition as the base material, otherwise welding aluminum is quick and easy in the flat position.. Vertical and overhead welding takes a little more more skill as the 'puddle' has a tendency to fall out of position.. As they say, practice makes perfect..

Good luck, but overall I think you'll find it reasonably easy..

Diana

Don't use Pure tungsten. It will vaporize on DC Electrode positive. You want to use Lanthanated of any percentage.

DCEP Aluminum TIG works fine as long as your torch can take the extra heat, and you don't attempt to weld aluminum thicker than your tungsten diameter.

Preheating the aluminum to a few hundred degrees F is good, and a little helium added to your argon will also help a lot.

Yikes... Don't try that on 6000 series aluminum alloys. You are almost garaunteed cracks.

OK, I have 1.5% Lanthanated 1/8 electrodes.

My torch is water cooled.

What if all I have is argon, is it still possible to weld?

What would be a good amperage for 1/8" electrode?

Right you are... That's why I added a cautionary note which said, as above:

If you have a welding set and the right set up, why dont you try it and see?

I just think that it would be good to ask first, but yes, eventually I will try that.

--Which alloy do you recommend? Turns out a pal of mine needs a bunch of al support frames made and I'm going to be in the same pickle (but I do have the AC option). Would you recommend different alloys for AC and DC tig?

The cracks are caused by trying to flow weld 6000 series aluminum to itself. You need to add a filler rod to change the metal in the weld to prevent cracking.

Yes pure argon is fine.

Amperage is set by your welding task and the machine setup. but you can't go wrong with 1 amp per 0.001" of wire diameter.