TIG Welding Aluminum Tips and Tricks

Due to its thermal properties, aluminum is one of the most challenging metals to weld. Aluminum requires the right amount of heat to achieve proper penetration without burning through the metal or running too cold. Additionally, aluminum really dislikes contamination, as even small portions can ruin the weld.

With all considered, TIG welding sounds like a perfect choice for aluminum welding. And it really is, due to its cleanliness and outstanding heat control. But aluminum TIG welding can be really challenging, especially for beginners.

We compiled these TIG welding aluminum tips and tricks to make your everyday aluminum welding easier. So, buckle up and check out the essential tips.

TIG Welding Aluminum
Photo by @random_video_studio92 (TikTok)

Why is Aluminum so Challenging to Weld?

Due to its lightweight and corrosion resistance, aluminum is a prevalent metal across many industries worldwide. However, its properties make it one of the most challenging to weld. Understanding the challenges is crucial in making the right approach to welding, and here is a quick overview:

• Oxide layer: When exposed to oxygen, aluminum forms an oxide layer that protects the base metal from corrosion. While corrosion resistance is advantageous in many applications, welding through the oxide layer is challenging. The oxide layer has roughly three times the melting point of the base metal, so burning through it will certainly burn through the base metal.

Source: https://teandersen.com/uploads/vfa97WUO/Technicalupdate-MaintenanceWeldingofAluminium.pdf

• Thermal properties: Aluminum has much higher thermal conductivity than mild steel or stainless steel. It dissipates the heat from the heat-affected zone (HAZ) five times faster than steel, so it requires more heat to achieve proper penetration. However, aluminum has a low melting point, so if you are not careful, you can easily overheat and burn through aluminum pieces. Therefore, successful welding requires the perfect amount of heat.

• Contamination: Aluminum is very susceptible to contamination. Dust, dirt, grease, gases, or moisture can contaminate aluminum, leading to porosity or reduced corrosion resistance.

Contamination in TIG Welding Aluminum
Photo by @Lennard Sihlis on Facebook

Why TIG Welding?

TIG welding perfectly addresses all the challenges associated with aluminum welding. Gas tungsten arc welding (GTAW) or TIG is a clean process with minimal risk of contamination.

In addition, TIG provides unmatched heat control. Welders often use it to weld extremely thin or delicate metals such as aluminum. It can work with both medium and low amps, so the risk of overheating is minimal.

So, it's no surprise that many welders recommend TIG welding as the go-to for aluminum. Below are the essential tips and tricks you’ll need to successfully TIG weld aluminum.

Aluminum TIG Welding
Photo by @issagoatmez (TikTok)

14 Essential TIG Welding Aluminum Tips & Tricks

Although TIG welding is a recommended method for aluminum, it can be very challenging, especially for beginners. GTAW is a manual method that takes two hands to operate. You manually control the feed and the torch, which can be overwhelming for some.

Add the challenges of aluminum welding to that, and you can have a bad time. But with a bit of practice, knowledge, and understanding, everything can change. So, follow these tips to learn more.

TIG Welding on Aluminum
Source: https://www.youtube.com/watch?v=WHuUt7fHHtM

1. Cleanliness is crucial

As noted, aluminum is susceptible to contamination, even the slightest traces. Therefore, make sure everything is squeaky clean before you even start welding. The more time you spend cleaning the pieces, the less you'll have to worry about contamination, porosity, or rework.

First, clean the aluminum surfaces and scrub off the oxide layer. Start by brushing the surface with a dedicated stainless steel brush. A carbon-steel brush can dig into the surface, leaving traces of carbon that make aluminum vulnerable to corrosion. You should also wipe your aluminium down with acetone (or rubbing alcohol). Use a clean rag to remove any oil, grease, and oxide layer.

Use a dedicated stainless steel brush to clean and remove aluminum oxide.
Source: https://www.youtube.com/watch?v=smwB3pO-Lr0

Keep in mind that the oxide layer forms naturally when aluminum interacts with oxygen. Therefore, you shouldn't wait too long before starting to weld after removing it.

Aluminum is all about cleanliness, so don't forget about your consumables. Make sure your tungsten electrode is not damaged or contaminated during previous welding. Also, remove any spatter or debris from the gas lens or cup, as they can interfere with the shielding gas coverage. Poor shielding will cause porosity or oxidation.

Overall, TIG welding aluminum will need to be sparkly clean. That includes pieces, shielding gas, cleaning tools, consumables, and accessories involved in TIG welding.

Prepare Everything Clean for TIG Aluminum Welding
Source: https://www.youtube.com/watch?v=9WvrJPn713Y

2. Provide a tight and even joint fit-up

Although the gap size depends on the metal thickness, most TIG welds on aluminum require a tight fit-up. You can even TIG weld thin aluminum sheets with no gap or filler metal (autogenous welding).

Nevertheless, the goal is to provide an even, tight joint fit-up when TIG welding aluminum. Uneven joints with gaps produce uneven welds. But, more importantly, they can lead to burn-through.

Burn-Through Defect During TIG Welding on Aluminum
Source: https://www.youtube.com/watch?v=kwnlcohZUZM

Uneven joints can also cause inconsistent heating inside the joint. Aluminum has one of the highest coefficients of expansion. So, overheating one part and underheating the other can lead to distortion, especially on thin aluminum.

So, always remember that even tight gaps produce uniform, good-looking welds. TIG welding is all about precision, so there is no room for errors.

TIG Welding on an Aluminum Edge
Photo by @welderman125 (TikTok)

3. Switch to AC current

TIG welding is one of the few processes that can utilize alternating current (AC). When TIG welding aluminum, AC current is mandatory due to its cleaning action.

In AC, the current oscillates between negative (EN) and positive (EP) cycles, which is advantageous for aluminum. The electrode negative (EN) portion focuses heat into the base metal, which promotes penetration. The electrode positive (EP) cycle focuses heat on the electrode, providing a cleaning action that removes surface oxide.

Therefore, before you even consider TIG welding aluminum, grab an AC TIG welder. We recommend checking out our YesWelder TIG200 ACDC-Pro pulsed AC/DC TIG welder, which is perfect for aluminum work.

TIG-200P-ACDC-PRO AC/DC Aluminum TIG Welder

Most new inverter TIG welders, including TIG200 ACDC Pro, will allow you to adjust two essential parts of AC current: balance and frequency. These factors can significantly affect the results of aluminum welding, as explained below.

4. Adjust AC balance

AC balance controls how long the current spends in each cycle during a switch from the negative to the positive side. By default, current in AC spends equal time in EN and EP cycles. That's the 50% balance, but you'll want to tweak it when TIG welding aluminum.

AC Balance for Aluminum TIG Welding
Source: https://www.weldpundit.com/ac-balance-in-tig-welding/

Most welders recommend tuning the balance to 65-70% EN and 30-35% EP. Doing so will provide enough heat to penetrate aluminum, while retaining a cleaning action.

Going over 75% EN can result in welds that appear dirty, crusty, or frosty due to overheating and poor cleaning. Excess EP can overheat the tungsten electrode, cause balling, and contamination.

TIG Aluminum Welds at 95% DCEN
Source: https://www.youtube.com/watch?v=DNtVRzFKQUY

5. Adjust frequency for aluminum thickness

Frequency adjusts how many times the current switches between EN and EP. Most AC TIG inverter welders have a default frequency of 120 Hz, which means the current switches 120 times in a second. Adjusting it can have different results on the weld.

Source: https://www.weldpundit.com/ac-frequency-in-tig-welding/

A lower frequency, around 50-60 Hz, creates a wider weld bead. A wide puddle with higher heat and greater penetration is better suited to thicker aluminum. So, you'll want to lower the frequency on thicker pieces.

Higher frequency (over 120 Hz) produces a narrow, tight weld bead. These properties make it ideal for thin aluminum and corner joints. Therefore, increase the frequency when working with thin sheets to promote precision.

TIG Aluminum Welds at 50hz vs 250hz
Source: https://www.youtube.com/watch?v=XzsfBV6_vNY&t

6. Use the right type and amount of filler rod

As an everyday welder, you are likely to use ER4043 or ER5356 TIG aluminum rods. These come in standard 36-inch lengths and diameters that range from 1/16-inch to 5/32-inch. The key is to use the right amount, size, and type for the given application.

Using too much filler rod piles up the bead, leading to overwelding. The heat is insufficient to melt and penetrate the pieces, resulting in poor fusion. Meanwhile, using too little rod can cause the pieces to overheat. A portion of the heat is transferred to the filler and base metal. So if there is not enough rod, more heat goes into the joint.

Rod diameter also matters. The thicker the rod is, the more heat it needs to melt. So, using too-thick rods may cause overheating and burn-through. Using a rod that is too small for the given metal won't do too much harm, but it can be time-consuming. For larger gaps, it will take time to fill everything in. It can also lack heat and penetration for the given pieces.

If you don't have a thin enough rod for the application, you can use aluminum MIG wire. Wires have a similar composition and the same diameter, but they come on spools. If you can straighten the wire, it can serve as a quick replacement rod.

7. Use high-purity, inert shielding gas

In general, aluminum and TIG welding require a high-purity, non-reactive shielding gas. 100% Argon is the most common choice, as it provides exceptional protection. Additionally, its inert nature means it won't react with molten aluminum and a heated tungsten electrode.

Coverage also matters. Shielding gas flow should be sufficient for the given conditions. If there is no wind or draft in the workshop, you don't need a high rate. In fact, high flow rates can create turbulence that sucks in the contamination. Consider using a gas lens or a cup kit to improve gas distribution around the weld.

TIG Welding Aluminum Using Gas Lens
Photo by @grumpyweld (TikTok)

8. Rework bad tacks

Tacking aluminum is always a good way to ensure precision and reduce the risk of distortion during TIG welding. However, bad tack welds can actually ruin puddle formation and overall aluminum welds. You'll notice bad tacks if they melt a portion of the base metal or appear larger than the weld bead you plan to run.

TIG Track Welding
Source: https://www.youtube.com/shorts/7RLfOpKz1wU

Unless the aluminum is super thin, you should always use a filler rod to tack the pieces. Starting tack welds should be the same size as the weld bead you will run. Making weld-like tacks will make your aluminum weld-start much easier.

Likewise, making slightly larger end-tack welds will help you finish the weld. By the end of the alumin weld, things get really hot. Having that extra tack ensures you won't blow out the end of the weld.

You should grind and rework any bad tacks. Instead of helping you, these can make running a bead much more challenging.

Reworking Defective Weld Tracks
Source: https://www.youtube.com/shorts/on3T6M9Noy0

9. Establish the pool before dipping the rod

Due to thermal properties and the oxide layer, aluminum needs some time to establish the weld pool. Once the arc starts, it takes a few seconds to remove the oxide and begin melting the base metal.

That's when you start feeding the rod. Once the puddle reaches the desired size and shape, you feed the rod. That way, you'll have proper rod wetting and an appropriately sized weld that penetrates the pieces.

Feed the Rod After the Puddle Forms Properly
Source: https://www.youtube.com/watch?v=VOqhh36Kcxo&t

10. Hold your torch properly

Mastering the TIG welding technique is quite a challenge for many new welders. Welding aluminum adds more difficulty to it, but with the right practice, you'll get some of the most satisfying welds.

Hold the torch tip close to the base metal. The distance between the torch tip and the base metal should be approximately the tungsten diameter, up to 1/4 inch. Moving the tip too far will widen the arc and the heat-affected zone (HAZ), eventually overheating the aluminum and making puddle control difficult.

The first step in proper technique is to hold and move the torch. Always hold your TIG torch in your dominant hand, which you lay flat against the table. TIG welding aluminum requires a pushing, with a slight backward tilt of 5 to 15 degrees.

11. Practice the move and the dab motion

As mentioned earlier, TIG welding involves manually feeding filler rod inside the joint. That means you'll be using both hands as you move. Therefore, coordinating the move and dab motion is crucial in producing sound aluminum welds.

Always feed the aluminum rod in front of the TIG torch as you push. The torch and rod should be roughly 90 degrees apart. The dominant hand with the torch is smooth and steady as it slides, while the other hand dabs the filler metal at the leading edge of the puddle.

The key is to get the hands to work independently. Accidentally touching the tungsten with your filler rod will contaminate it, so be careful. If you are new to TIG welding, you could practice the movement and coordination without striking an arc. Once you catch the rhythm of the move and dip, you are set for success.

TIG Welding Aluminum Technique
Source: https://www.youtube.com/watch?v=cVDOZDOQ1U4

12. Puddle control is crucial

Once the aluminum weld puddle has established, it can be difficult to control. The puddle picks up speed as it gets hotter, so it can get out of control really fast.

The key to a successful TIG aluminum weld lies in controlling the puddle. Use the auto-darkening welding helmet to maintain clear visibility of the puddle. Keep the speed, shape, and size consistent across the joint.

Once the puddle establishes, you can use the foot pedal to reduce the current by a few amps to avoid puddle washout. Keep in mind that heat builds faster at the edge of the aluminum pieces. Therefore, adjust the pedal to prevent overheating. However, significantly reducing the amps can create an erratic arc and make you lose the puddle, so be careful.

Use the Foot Pedal to Control Heat Better
Source: https://www.youtube.com/watch?v=VOqhh36Kcxo&t

13. Adjust post-flow

Post-flow is a handy feature that keeps shielding gas flowing for a few seconds after releasing the trigger. Although it will use more gas, doing so will significantly help protect the weld, tungsten, and TIG torch consumables once you finish the weld.

As noted above, TIG aluminum welding runs pretty hot. Once you finish the weld, the metal and tungsten will get red hot. Like any metal, heated tungsten can absorb atmospheric contaminants, rendering it unusable later. Using extra shielding gas to cool everything and protect it will help your consumables last longer.

TIG Aluminum Welding Runs Hot – Metal and Tungsten Get Red Hot
Source: https://www.youtube.com/watch?v=iq3NVujs6Fw

14. Polish welds for extra aesthetics

TIG can produce some of the most visually pleasing welds, especially on metals such as aluminum. Stacking the dimes is a TIG-exclusive appearance that looks pretty satisfying.

If you want an even better appearance on the visible aluminum welds, you can polish them. Tape around the edges of your weld, then polish it for a clean, perfect look.

Polishing the welds is not mandatory, especially if they are not on the visible part of the assembly. So, it's up to you to figure out how you want to finish the welds.

Polish Welds for Extra Aesthetics
Source: https://www.youtube.com/watch?v=9NlGNmWKWNA

Final Thoughts

TIG welding is many welders' preferred choice, especially for thin sheets. Its heat control, cleanliness, and precision are ideal for a delicate metal, such as aluminum.

But TIG welding aluminum isn't always a breeze, particularly for new welders. Many things can go wrong; Some challenges, such as burn-through, contamination, or a lack of fusion, emerge from the metal's properties. Others come from TIG welding itself being a challenge to master.

However, things don't have to be so dire. As long as you understand the challenges, you can make the right approach. That means using AC, setting balance and frequency correctly, cleaning aluminum, and practicing technique. Once all pieces of the puzzle come together, you'll produce some of the most satisfying aluminum TIG welds.

Learning Aluminum TIG on Yeswelder 200P AC/DC PRO
Source: https://www.youtube.com/watch?v=GfylA4O96i4

👏 You may be interested in the following:

• Right TIG Filler Rods For Different Metals
• How To TIG Weld Different Thickness Metals
• Common TIG Welding Defects And How To Deal With Them