Today, we tried some DC aluminum welding at the shop. We used 3/32" 2% Thoriated Tungston ground to a point, DC Straight Polarity, a gas lens, and Helium Gas. Talk about a deep penetrating, weld! It welds totaly different than AC. The "puddle" forms much quicker, but there is a film that floats on the top (even when the metal is properly prepped) that makes it difficult to tell when the metal is ready. When finished and brushed, the weld doesn't look half bad! I'll post some pics later, but this should be considered a definite option for folks with DC Tig welders, or those folks who have an AC welder but need to occasionally weld aluminum that is heavier than their AC capabilities. It takes substantially less amperage to weld DC aluminum than AC. On thin materail, the definite choice is AC. But, for thick material that needs heavy penetration, DC seems like a very viable option.

 

Interesting. I have never actually tried aluminum welding with DC, but I might just have to give it a shot...

 

A guy at work told me about this. He claims he only uses DC to weld Al. I've never tried. It seems like all the Al I weld on my car is thin, but I think I'll give her a shot!

 

Here are some pics. The helium we were using was "balloon grade", whatever that means. I imagine it wasn't totally pure. We weren't sure what series aluminum this was, so I'm not sure we used the correct filler (we used 4043). This was also the first attempt so I'm sure with some practice, and verified correct materials, the results could be even better. Look at the size of those chunks of aluminum! The welds were rediculous quick, and the penetration was amazing. Not as pretty as AC, but if you have some hefty aluminum to weld, this'll do it!

 

Wow! That looks much better than I thought it would. I believe "balloon grade" has a small percentage of oxygen in it so kids don't kill themselves when they breathe it in.

 

i bet you have to have a quick stitch or else you'll blow through? how thick is that piece you're welding? looks good! Ive never used a tig for aluminum,(nevermind DC voltage) we cheat and use a spool gun.

 

1 3/16". We did a quick test on some 1/8" and it did tend to sag a little easier than AC, but still welded OK. A quick stitch on thinner material might not be a bad idea.