TIG Welding Aluminum DC Electrode Negative
Does your TIG welding machine have enough amperage to weld thick Aluminum? Are you tired of pre-heating only to find that your tungsten cannot withstand the constant AC arc?
Direct Current Electrode Negative (DCEN) or DC(-) TIG welding Aluminum.
There are no short cuts or forgiveness when it comes to welding Aluminum, especially thin material.
DC(-) TIG welding Aluminum does not work on all types of Aluminum, but fortunately, 6061 is one that can be welded using this process. Also, beware that DC(-) provides no cleaning action whatsoever. A good wire brushing followed by an Acetone wipe is critical to being successful. Here are some of the Aluminum types that can be welded using DC(-): 6061; 1100; 2219; most A-356 and A-357 Casting (although you get a dirty weld). Do Not attempt any 5XXX series Aluminum or use filler materials that are 5XXX series. Acceptable filler materials are: ER4043; 1100 and 2319.
TIG Welding Aluminum DC(-) Procedures for 1/4″ to 1″ 6061-T6 aluminum plate:
- Torch: TIG Torch rated at 300 amps – Amperage: 175 to 225
- Tungsten: 2% Ceriated – Tungsten Diameter: 3/32″
- Tungsten Tip: Pointed – Pre-Heat: not required
- Filler Material: ER4043
- Filler Material Diameter: 1/16 to 3/32″
- Shielding Gas: 100% Helium @ 40-50 CFH
- Back-up Gas: not required – Polarity: DC Negative
TIG Welding Aluminum DC(-) Technique:
Initiate arc and hold amperage at about 200 amps. Dwell at the beginning for about 7 to 10 seconds. A puddle will form under the oxide layer. The puddle will not be shiny but when you add the filler, a better definition of the puddle will form. Do a bead-on-plate first, progressing to a fillet weld. Wire brush to improve appearance.