Every welder knows that you’ll get a much cleaner weld that is more likely to pass inspection if you use AC power when TIG welding aluminum. There’s no debate there for the most part. However, you will find a far more spirited debate online about whether you can or even should TIG weld aluminum with DC power. Is this possible? Is this desirable?
In many cases, AC will do the job just fine, why take a chance on a different method? However, there are special situations where a welder may want to consider experimenting with a TIG weld on DC power.
Choose the Right TIG Welding Application for DC Power
The most common reason to try DC power on Aluminum is a situation when the metal is thick, usually thicker than ½” in most cases. Aluminum could warp if you are welding with AC power and need to get enough penetration for a strong weld.
If you try to AC weld a thicker piece of aluminum there’s a chance you could warp, distort, or burn through the metal. Aluminum is notoriously tricky, as a little pre-heating can help, but too much pre-heating can cause big problems when you start welding.
Choose the Right Shielding Gas
TIG welders typically use pure argon shielding gas, especially for metals that are ½” thick or less. However, once you’re working with thicker aluminum, then you’ll need a helium-argon gas mixture in order to dig deep enough into the weld joint. If you’re going to give DC TIG welding a shot, then you’ll need to get the right gas into the mix, and helium-argon is a good place to start. Some welders suggest using 100% helium shielding gas for TIG welding thicker metals as well.
Issues to Consider with TIG Welding Aluminum on DC
You’re going to send a lot of heat into the weld joint when you’re running DC power. This is great if you need a lot of penetration, but things can get out of hand very quickly. Welders who have experimented with this have noted that they created sloppy welds that are OK if you need something done in a pinch. However, if you’re going to be inspected, then you may not want to go this route unless you have experience.
TIG welding machines and welding supplies will also deliver different results. Newer machines and inverters may deliver different results than older machines. In addition, some welders note that they have had better success TIG welding aluminum on DC by using thicker, much thicker, electrodes for their welds.
Should YOU Try TIG Welding Aluminum on DC Power
The one point of consensus you’ll find online is that the welders who make DC TIG welding work the best on aluminum are welders with a lot of experience. This isn’t a process to dive into if you’re just getting the hang of TIG welding. Focus on cleaning your metal properly, using your foot pedal, and keeping a close eye on the weld puddle; aluminum can melt very, very fast if you aren’t careful!
The two situations that are most appropriate for this type of welding is a thick piece of aluminum that you don’t want to risk distorting and an emergency situation when you need a quick weld and DC power is your only option. Keep in mind that some welders can create a clean weld, but there’s a good chance your first passes with this method won’t pass inspection!
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