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 aluminum, which is why it needs to be removed before welding.
The welding machine must either be made for TIG welding (such as this one) or have the necessary accessories.
A leg current control is necessary because heat builds up as the weld is started, requiring less heat from the electrode towards the end of the weld.
For best results use AC (Alternating Current) at high frequency (with high frequency tungsten electrodes do not need to come in contact with aluminum, reducing contamination risk).
Direct current is used as a limited alternative, but results in higher heat levels and poor oxide scavenging on the electrodes.
The torch nozzle may also have been selected for use on aluminum. When the diameter of the electrode is changed, a wide range of heat inputs can be used on 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.
Newer aluminum alloys such as the HTS-2000 provide a cost-effective method for welding aluminum. It can be used with any heat source.
Ac Tig Welding
- The electrode tip shape for AC TIG welding is a “ball”.
- This “ball” = 1 to 1½ times the diameter of the tungsten
- TIG welding amperage can be controlled in different ways, including using the AMPtrol on the torch, the foot pedal control and simply the machine setting. The remote control allows 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 amperage. These torches are usually smaller and less expensive.
- The water-cooled unit acts like a radiator on a car. Water is passed through the torch and circulated through the cooler by a pump. These units can operate at high amperage and for long periods of use.
- A slight leading angle allows the user to see the puddle, especially when adding filler.
- The filler can be immersed in a puddle or placed in a joint and moved back and forth.
Aluminum alloy
Several aluminum alloys have been developed for the TIG welding aluminum process.
The most popular welding aluminum is either pure aluminum 1xxx or aluminum manganese alloy 3003.
Aluminum is repaired or fabricated with aluminum brazing (low cost, strong welds) using the HTS-2000 brazing rod.
They are identified in a 4-digit system, with the first digit denoting the metal alloyed with aluminum:
- 1xxx – 99% pure aluminum, no alloys
- 2xxx – aluminum copper alloy
- 3xxx – aluminum manganese alloy
- 4xxx – aluminum silicon alloy
- 5xxx – aluminum magnesium alloy
- 6xxx – magnesium, silicon and aluminum alloys
- 7xxx – zinc and aluminum alloy
- 8xxx – Tin or other metals and aluminum
Recommended filler metal
The filler metal for TIG welding aluminum must be of high quality and without contamination.
Recommended filler metals for various aluminum alloys:
| Base Metals | Recommended Filler Metals (1) | |
| For maximum as-welded strength | for maximum elongation | |
| election Commission
1100 |
1100
1100, 4043 |
EC 1260
1100, 4043 |
| 2219
3003 3004 5005 |
2319
5183, 5356 5554, 5356 5183, 4043, 5356 |
(2)
1100, 4043 5183, 4043 5183, 4043 |
| 5051
5052 5083 5086 |
5356
5356, 5183 5183, 5356 5183, 5356 |
5183, 4043
5183, 4043, 5356 5183, 5356 5183, 5356 |
| 5050
5052 5083 5086 |
5356, 5183
5554, 5356 5356, 5554 5556 |
5183, 5356, 5654
5356 5554, 5356 5183, 5356 |
| 6061
6063 7005 7039 |
4043, 5183
4043, 5183 5356, 5183 5356, 5183 |
5356 (3)
5356 (3) 5183, 5356 5183, 5356 |
notes:
(1) Recommendations are for plate of “0” temper.
(2) The ductility of the weld of these base metals is not much affected by the filler metal. The elongation of these base metals is generally less than that of the 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 weld reinforcement to compensate for 5356’s lower conductivity.
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
Notes
- When welding starts break the tungsten and let it ball or ball the copper plate
- Aluminum turns into a mirror color when melted
- aluminum requires more amperage than steel of the same thickness due to heat dissipation
- Be sure to determine the aluminum base type before welding
- Some aluminum is not weldable by the tig welding aluminum process
- add more filler to the aluminum weld
Advantages and Disadvantages of Aluminum TIG Welding
Benefit
- Filler rod may or may not be necessary
- AC Polarity for Aluminum and Magnesium
- high quality welds
- all position welding
- Can be used on a variety of metals
- Excellent on very thin material
- fusion welding is possible
- no trauma
- no splatter
- high efficiency
Damage
- lack of portability (shielding gas cylinders and hoses)
- Not ideal for outdoor welding – shielding gas is susceptible to wind and drafts
- clean base material required
- low deposit rate
- high operational skills required
- often slow
Read more: GTAW Welding Explained
Metal cleaning methods
Common methods for cleaning aluminum surfaces for welding
| types of cleaning | ||
| compounds extracted | welding surfaces only | full piece |
| oil, grease, moisture, and dust (use any
method listed) |
– Wipe dry with mild alkaline solution.
– Wipe with a hydrocarbon solvent such as acetone or alcohol. – Wipe with proprietary solvents. – Dip the edges, use any of the above. |
– lack of steam
– sprinkle degrees – lack of steam – Dip in alkaline solvent – Immerse in proprietary solvents |
| oxides
(use any method listed) |
– Dip the cutting edge in a strong alkaline solution, then water, then nitric acid. rinse with water and dry
– Wipe with proprietary deoxidizer – Remove mechanically, such as by wire-brushing, filing or grinding. For critical applications, degrease all joints and adjacent surfaces immediately prior to welding |
– Dip in strong alkaline solution, then water, then nitric acid.
– Finish by rinsing with water and drying – Immerse in proprietary solution |
Brazing rods are an alternative to TIG welding aluminum
New technology has recently been developed that enables welders to make or repair aluminum that is stronger than with 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 process works for aluminum or any aluminum alloy.
5 Tips for Understanding Aluminum TIG Filler Metals, Setup and Welding
Here are some of the most common methods for optimizing results. Consider these five tips that can help you deliver better performance when TIG welding aluminum.
- Choosing the Right TIG Filler Metal .Typically, any filler metal used for MIG welding can also be found in TIG rod form. Some of the most commonly used alloys for TIG welded aluminum are 4043, 4047, 4943, and 5356. The metals dependent on the 4xxx series share many of the same characteristics.
4043 bar is a good all-around filler metal for general crafting. While it has a lower melting point and provides less stress (thanks to its silicon content), it does not provide the strength or hardness of the 5xxx series filler metals. 4047 bar also has a low melting point, but it is composed of a 12% silicon content, so it has minimal shrinkage and deformation compared to aluminum filler metals. Due to its high silicon content, 4047 bar also produces very shiny welds, making it popular for aluminum toolboxes. Rod 4943 can be used as a substitute for filler metal 4043 or 4047. The most commonly used aluminum bar, 5356, offers the highest strength and ductility, but there are many other factors that affect the choice of filler metal. Always refer to the aluminum filler metal selection chart to select the most appropriate filler metal for a particular application.
TIG filler rods are available in standard 36 inch lengths and diameters ranging from 1/16 inch to 5/32 inch for some alloys. For larger welds, choosing a larger diameter bar can result in productivity gains by filling the weld faster. TIG filler metal comes in a variety of packaging options, such as 1-pound tubes, 10-pound boxes and 40-pound boxes.
Compared to other materials such as steel or stainless steel, aluminum has a higher rate of thermal conductivity. As a result, it draws heat out of the weld pool more quickly and requires more energy to reach penetration.
- Prepresent base material .The steps the welder and company take to clean the base material depend on the quality of the weld the operation needs to achieve. Critical applications often require more careful cleaning when TIG welding aluminum, while more aesthetic applications may not remove the oxide to prevent scratches next to the weld.
When preparing aluminum for welding, it is best to clean the surface with an unused paper towel or rag and a cleaner such as acetone. It removes contaminants such as dirt and hydrocarbons such as oil, paint or adhesives. Shop rags should not be used as they may still contain dirt or oil.
After removing surface stains, remove the aluminum oxide layer that acts as an insulating barrier with a stainless steel wire brush, reducing the risk of weld contamination that can lead to pitting. Be sure to use a new stainless steel wire brush or a special aluminum brush to avoid cross-contamination with other materials.
- Adjusting Machine Settings and Parameters .The most typical setup for TIG welded aluminum involves the use of a TIG AC welding power source with 100% argon shielding gas. Keep in mind that the machine should not be too small. A general rule of thumb is 1 amp per 0.001 inch of material thickness. Therefore welding a 1/4-inch fillet weld would require a 250-amp machine. Machines that are too small in size will not provide enough amperage for the job, resulting in too little heat or part preheat needed to properly set up the solder puddle. It can also put extra strain on the power supply by welding at full power for long periods of time.
Using a DC TIG to weld aluminum is not a common setup, but it can be done. DC TIG requires the use of a shielding gas that is helium or a mixture of helium and argon, providing a hotter welding arc and deeper penetration. But since the DCEN process does not have the same cleaning effect as the anode part of the AC process, the preliminary steps to clean the base material and remove the oxide layer are critical.
Many TIG welding power sources today have some sort of preset function to help ensure that the operator is welding within the correct parameters. Using preset parameters can be especially helpful for less experienced welders. More experienced welders can adjust the frequency and balance to accommodate their arc taper. The higher the frequency setting, the narrower the arc cone for a narrower penetration profile and less arc deflection.
Adjusting the balance setting will change the amount of time spent in negative electrode mode compared to positive electrode mode. The balance is tilted more towards the positive electrode providing more cleaning action to remove the oxide layer and clean the base material during welding. The higher the negative electrode face, the faster the travel speed and the more heat is transferred to the base material leading to fewer cleaning bands outside the welding zone. It is important to balance the two depending on the condition of the base material and the needs of the application.
- Follow the “Hot and Fast” Rule .The best way to overcome lack of fusion or other problems with aluminum TIG welding is to weld hot and fast. That is, start with enough amperage to set up a puddle quickly (within a second or so), then start soldering immediately and maintain a good travel speed. Some operators go slow to achieve better penetration. Do not stand in a weld puddle or proceed too slowly as this transfers more heat to the base material than necessary and can significantly reduce the strength of the HAZ.
5. Proper handling and storage of filler metals.Following best practices for the storage and handling of TIG filler metals reduces the risk of contamination that can lead to porosity and weld defects. Have separate containers for each filler rod instead of mixing them together, and be sure to always seal the sticks and store them in a dry place without extreme temperature fluctuations. If filler metals are not stored where the parts are to be welded, be sure to bring the rods to the welding area for at least 24 hours before welding them. This allows the rods to acclimatize to room temperature. Storing filler metals in a cold, air-conditioned office and then bringing them into a heated workshop for welding can cause condensation—the moisture can add porosity to the weld. Multiple cross dew points can also cause a thick oxide layer on the aluminum rod.
Conclusion
All in all, welding aluminium with TIG is a fabulous and worthwhile endeavor. Not only can one fabricate beautiful and sturdy creations, but they’re also gaining valuable practical experience. The right equipment and precautions taken before, during, and after the job should always be in mind when welding any type of material. In addition to being mindful of best practices for welding with TIG, it’s essential to be aware of the specific details for aluminium as well – these instructions must not be overlooked! Welding correctly becomes easier as you become more familiar. If you’re interested in learning how to weld aluminium with TIG, don’t delay any further. With a solid knowledge base and some practice under your belt you will soon master this skill. You may even surprise yourself at the prosiness of creating lasting welds from expertly machined pieces of aluminium!