Yes, you can TIG weld aluminum. As a matter of fact, TIG is the method most frequently chosen to weld aluminum, especially in the lighter gauges. In addition to the TIG welding machine, the process requires a non-consumable tungsten electrode, a high-quality filler metal, argon shielding gas, and a meticulously-cleaned surface to remove all oxide buildup. (Oxide has a higher melting point than aluminum and could end up unmelted in the weld).
Because aluminum is an excellent conductor of heat, it requires lots of heat initially. However, as the process moves along, the heat starts to move ahead of the arc, pre-heating the base metal and demanding a current reduction. For this reason, welding operators should have a foot pedal that allows them to decrease the current without interrupting the weld.
How to TIG Weld Aluminum
Properly control the heat: Welders can control when they add the filler metal. They establish the weld pool and ensure proper penetration before adding it. As the weld progresses, the heat must be controlled (reduced) to prevent a runaway pool or burn-through. A shorter arc length can help contain the heat to a smaller area.
Use the correct polarity: Even though the aluminum is adequately cleaned, an oxide layer can begin re-forming. This makes it essential to use alternating current (AC) polarity with TIG welding. AC polarity provides a cleaning action, removing any oxide layer on the aluminum and allowing the welder to see the molten weld pool.
Set the right amperage: The rule of thumb for aluminum TIG is one amp for every thousandth (0.001”) of material thickness. That means a 1/8” (0.125) thick aluminum part would require about 125 amps.
Getting that “stacked dimes” look: Adding more filler material creates a cooling effect on the backside of the weld puddle, producing the stacked-dimes appearance of the finished weld.