TIG welding aluminum requires a shielding gas (usually argon), a tungsten non-consumable electrode and a clean surface to remove any oxide buildup.
The oxide has a higher melting point than the aluminum itself, which is why it needs to be removed before welding.
The welding machine needs to either have been built for TIG welding (like these) or has the necessary accessories.
A foot current control is essential since heat builds up as the weld is started, requiring less heat from the electrode toward the end of the weld.
For best results use AC (alternating current) at a high frequency (with high frequency the tungsten electrode doesn’t need to come in contact with the aluminum, reducing contamination risk).
Direct current is used as a limited alternative but results in higher heat levels on the electrode and poor oxide cleaning.
The torch nozzle also must have been selected for use on aluminum. When the diameter of the electrode is changed, a wider range of heat input can be used at different metal thicknesses.
In the hands of a skilled welder, TIG looks better and seals better than MIG aluminum welding. MIG aluminum welding is preferred for thicker pieces of metal.
New aluminum alloys such as HTS-2000 offers a lower-cost method for welding aluminum. It can be used with any heat source.
AC TIG Welding
- Electrode Tip Shape for AC TIG Welding Is a “Ball”
- This “Ball” = 1 to 1½ Times the Diameter of the Tungsten
- TIG welding can be amperage controlled in different ways, including an AMPtrol on the torch itself, foot pedal control, and simply using the machine setting. Remote controls allow the user to start hot and reduce amperage as the weld progresses.
- The air-cooled unit above simply uses the gas flow to cool the torch. Therefore, care must be taken not to overheat the internal torch parts, especially when using high amperages. These torches are typically smaller and less expensive.
- The water-cooled unit operates much like a radiator on a car. Water is flowed through the torch and circulated through the cooler by a pump. These units can operate at higher amperages and for longer use.
- A slight leading angle allows the user to see the puddle, especially when adding filler.
- The filler can be dipped into the puddle or placed in the joint and moved forward and back.
Read more: Is AC or DC better for welding?
Many aluminum alloys have been developed for the TIG welding aluminum process.
The most popular welding aluminum is either pure aluminum 1xxx or an aluminum manganese alloy 3003.
The repair or fabrication of aluminum is done with aluminum brazing (lower cost, stronger welds), using HTS-2000 brazing rods.
They are identified in a 4 digit system with the first digit indicating the metal alloyed with the aluminum:
- 1xxx – 99% pure aluminum, no alloy
- 2xxx – aluminum copper alloy
- 3xxx – aluminum manganese alloy
- 4xxx – aluminum silicon alloy
- 5xxx – aluminum magnesium alloy
- 6xxx – magnesium, silicon and aluminum alloy
- 7xxx – zinc and aluminum alloy
- 8xxx – tin or other metal and aluminum
Recommended Filler Metals
Filler metals for TIG welding aluminum need to be high quality and without contamination.
Recommended Filler Metals For Various Aluminum Alloys:
|Base Metal||Recommended Filler Metal (1)|
|For Maximum As-Welded Strength||For Maximum Elongation|
5183, 4043, 5356
5183, 4043, 5356
|5183, 5356, 5654
(1) Recommendations are for plate of “0” temper.
(2) Ductility of weldments of these base metals is not appreciably affected by filler metal. Elongation of these base metals is generally lower than that of other alloys listed.
(3) For welded joints in 6061 and 6063 requiring maximum electrical conductivity use 4043 filler metal. However, if both strength and conductivity are required, use 5356 filler metal and increase the weld reinforcement to compensate for the lower conductivity of 5356.
Source: (1) Lincoln Electric
Sample Amperage Chart
Base Metal Tungsten Filler Rod Amperage for TIG welding aluminum
0.010″ – 0.035″ 0.040″ 0.024″ – 0.030″ 5 – 25
0.035″ – 1/8″ 1/16″ 0.030″ – 0.045″ 20 – 85
3/32″ – 1/4″ 3/32″ 1/16″ – 3/32″ 50 – 180
3/16″ – 3/8″ 1/8″ 3/32″ – 1/8″ 171 – 250
5/16″ – 1/2″ 5/32″ 1/8″ – 3/16″ 200 – 320
- Break tungsten off and allow it to ball when welding starts or us a copper plate to ball
- Aluminum turns to a mirror color when molten
- Aluminum requires higher amperages than the same thickness steel due to heat dissipation
- Be sure to determine aluminum base type before welding
- Some aluminum is not weldable by the tig welding aluminum process
- Add more filler to aluminum welds
Advantages and Disadvantages of Aluminum TIG Welding
- A Filler Rod May or May Not Be Necessary
- AC Polarity for Aluminum & Magnesium
- High Quality Welds
- All Position Welding
- Can Be Used on a Variety of Metals
- Excellent on Very Thin Materials
- Fusion Welding is Possible
- No Slag
- No Spatter
- High Efficiency
- Lack of portability (Shielding Gas Cylinder & Hoses)
- Not ideal for outdoor welding – the shielding gas is susceptible to wind & drafts
- Requires Clean Base Material
- Low Deposition Rates
- High Operator Skill Necessary
- Often Slow
Read more: GTAW Welding Explained
Metal Cleaning Methods
Common Methods for Cleaning Aluminum Surfaces for Welding
|Types of Cleaning|
|Compounds Removed||Welding Surfaces Only||Complete Piece|
|Oil, grease, moisture, & dust (use any
|– Wipe with mild alkaline solution and dry.
– Wipe with hydrocarbon solvent, such as acetone or alcohol.
– Wipe with proprietary solvents.
– Dip edges, using any of above.
|– Vapor degrease
– Spray degrease
– Steam degrease
– Immerse in alkaline solvent
– Immerse in proprietary solvents
(use any method
|– Dip edge in strong alkaline solution, then water, then nitric acid. Finish with water rinse and dry
– Wipe with proprietary deoxidizers
– Remove mechanically, such as by wire-brushing, filing, or grinding. For critical applications, scrape all joints and adjacent surfaces immediately prior to welding
|– Immerse in strong alkaline solution, then water, then nitric acid.
– Finish with water rinse and dry
– Immerse in proprietary solutions
Brazing Rods an Alternative to TIG Welding Aluminum
New technology has recently been developed which enables welders to fabricate or repair aluminum stronger than a TIG welding machine using a simpler process.
Now all that is needed is a heat source such as mapp gas or propane, a turbo tip and a brazing rod.
This procedure works for aluminum or any of the aluminum alloys.