I know that aluminum is only welded in AC mode because of the unique metal properties that require cleaning and penetration to be both performed simultaneously and the alternating current can do that but I do not have an AC TIG machine available at the moment..
I remember back in the day when an old friend who was teaching me TIG welding long ago talked about how you can use DC machine to TIG weld aluminum but if you use helium as the shielding gas. But I wasnt really paying attention at a time which I regret now as we can not talk about this now.
I did some searching but I failed to find a detailed info about it. https://weldingpros.net/how-to-tig-weld/ I found this article linked to one reddit thread about DC welding aluminum but even that article only states that it is possible but without further details. It does say that in order to do that you need to weld thick aluminum which is exactly what I need to do so it did give me some reassurance. I need to weld two 1/2 in sheet metals to form an L shape beam.
I have a pretty good DC TIG welder available on me. It has over 200 amps which means that it can handle the thickness with ease. I also have a big cylinder of helium available but I am not sure if this is something that I can do.
If anyone here had an experience like this I would be very grateful if you could share it with me. How did the metal behave? Did you have a clean or a dirty contaminated weld? Did the oxidation from the aluminum surface go under the puddle?
The answer to your question is no. DC doesn't work with aluminum; this requires AC welding, which is done by TIG. Yes, what you want to do may be possible but it'll require a different electrical source than the one that comes in your standard home garage or workshop! You can electrocute yourself with AC or DC voltages - just not both at the same time!
Aluminum is usually arc welded with two shielding gases - argon and helium. Various mixtures of argon and helium along with pure argon and pure helium are used.
As a shielding gas, pure argon is often used to produce excellent welds. It is often used for both gas metal arc welding of aluminum and gas tungsten arc welding of aluminum that pure argon is the most popular shielding gas. In general, mixtures of argon and helium are more commonly used than pure helium, except for some specialized GTAW applications.
I searched for detailed information about it but was unable to find it. There is an article on https://weldingzilla.com/best-tig-welders/, but even the article referred to one Reddit thread about DC welding aluminum but said that it could be done even without further details. The article does mention that you need to weld thick aluminum to accomplish this, which is exactly what I need to do, so it did give me some comfort. To form an L-shaped beam, I must weld two 1/2 in sheet metals together.
The differences between using argon helium mixtures and argon for welding aluminum need to be considered. It is important to understand the effects of these gases on welding.