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TIG Welding Thin Steel: Techniques, Tips & Tricks
Welding anything on a thinner scale or sheets can be a nightmare for many welders. One wrong step and you will blow holes, warp, or distort metals with excessive heat.
It takes time, practice, patience, and a suitable method to master thin-metal welding. With its heat control, features, and low-amp capabilities, TIG welding is a perfect choice for the job.
In this article, we compiled useful techniques and tips for TIG welding thin steel. Follow our guide to learn how to TIG weld sheet metal like a pro.
TIG Welding Thin Metal
Source: https://www.youtube.com/watch?v=dpQ22DdN11E
Can You TIG Weld Thin Steel?
Most certainly yes: TIG welding is one of the best methods for welding thin sheets of metals like steel and stainless steel, or aluminum. Gas Tungsten Arc Welding (GTAW), or TIG, offers unique advantages that make welding thin metal and varying metal thicknesses convenient.
TIG Welding Very Thin Metal
Source: https://www.youtube.com/watch?v=ovLqbfcmjn8
The most notable advantages that make TIG perfect for sheet metal welding include:
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Low-amp welding: TIG welders can start an arc at as low as 5-10 amps. Industrial and micro-TIG machines successfully work at the single-digit amperage, allowing welders to weld down to 0.0002" thick metals.
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Heat control: New TIG welding machines let you control the entire process from start to finish. Using a foot pedal or torch control, you can adjust amperage on the fly. Controlling heat is crucial to preventing overheating of thin metals.
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Precision: TIG equipment includes consumables and accessories built for thin-metal welding. Low-diameter tungsten and fillers narrow the HAZ and provide the necessary precision.
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Cleanliness: GTAW is a clean process that produces the highest-quality welds. Lack of contamination ensures even heating, preventing thin-metal welding issues.
Clean, High-Quality TIG Aluminum Welds
Source: https://www.youtube.com/watch?v=dpQ22DdN11E
Why is Thin Steel Challenging to Weld?
Welding anything below 18 gauge can be quite a challenge for many welders, especially beginners. Thin metals are delicate and require an ideal amount of heat.
Understanding the challenges is the first step in successful welding. Knowing what went wrong will help you adapt and make adjustments.
Pulsed TIG Welding on Thin Metal
Source: https://www.youtube.com/watch?v=dpQ22DdN11E
The most common issues with thin steel welding include:
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Burn-through: Using too much heat will burn through the thin metal. Seeing holes in welding is never a good sign, and with thin sheets, they can be quite frustrating. The cause is simple: either too much heat or moving too slowly across the joint.
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Warping: Metals expand and contract as they heat up. As a result, localized heating caused by welding can warp thin metals. Steel doesn't dissipate heat like aluminum, but sheets can still warp due to a wide heat-affected zone (HAZ).
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Distortion: Uneven heating, expansion, and contraction can cause thin metals to distort from their original shape. Localized plastic deformation can compromise weld integrity, and once again, heat is the cause.
Keep in mind that other defects, such as overwelding, lack of fusion, undercutting, or porosity, can also occur on thin steel. However, these can occur on any piece and are usually caused by poor technique, parameters, or shielding.
10 Useful Tips on How To TIG Weld Thin Steel
Understanding the challenges will help you know what you are dealing with. But in this section, we'll focus on the tips and techniques you'll need to weld thin steel successfully.
Here is a quick list of useful tips for TIG welding thin steel:
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Pay attention to preparation
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Use the small-diameter tungsten
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Choose the right filler rod
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Use multiple tack welds
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Adjust controls and parameters
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Control the heat
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Adjust the technique
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Consider using heat sink bars
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Use a heat sink if needed
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Try to repair burn-throughs
Let's further explore each tip and how it can change your perspective on thin steel welding.
Source: https://www.youtube.com/watch?v=5dEDADNiOxQ
1. Clean and prepare the thin metal before welding
TIG welding dislikes contamination. Any dirt, oil, moisture, dust, paint, or rust can compromise weld integrity and cause uneven heating. The more time you spend on preparation, the better welds you can expect.
The same applies to thin steel. Although mild steel is less reactive than aluminum or stainless steel, contamination can cause uneven heating or porosity. So, always thoroughly clean the surface before welding.
Clean the Surface before Welding Using a Wire Brush
Source: https://www.youtube.com/watch?v=ovLqbfcmjn8
TIG welding thin steel requires flush surfaces. As the pieces get thinner, you need less and less gap, to the point where there is no gap. You can TIG weld steel sheets without any gap or added filler metal, as the molten surface metal is enough to form strong fusion without overheating the joint.
Weld thin pieces only once you have a well-clamped, clean, flush surface with tight fit-up. Proper preparation will reduce the risk of common issues when welding thin pieces. It will also save you time on rework and post-weld cleaning.
Proper Preparation before TIG Welding Thin Metal
Source: https://www.youtube.com/watch?v=AicYjxOdI6A&t
2. Choose and prepare tungsten for thin metal
GTAW uses non-consumable tungsten electrodes that carry a current and support an arc. The key to successful TIG welding thin steel is in choosing the right tungsten type and size for the given metal.
Common TIG Welding Tungsten Types
Source: https://www.youtube.com/watch?v=wQ-ePKKjFWA
For steel, you can use any of the recommended tungsten types: lanthanated, ceriated, or thoriated. Type is less important; you can choose whichever suits your personal preferences.
WL20 Series 2% Lanthanated TIG Welding Tungsten Electrode
What matters more is the diameter. The thinner the tungsten, the fewer amps it takes to heat up and create an arc. The less heat you apply to thin sheets, the less likely you are to blow through them. Also, a smaller diameter means a more focused arc and a narrower HAZ.
We recommend starting with 3/32" or 1/16" tungsten for delicate work. A 1/16" tungsten needs fewer amps and provides a tighter arc. But, it also means you need to run slower, which can focus more heat into the joint.
If you are not confident you can keep up the pace without overheating the pieces, switch to 3/32" tungsten. Using a slightly larger tungsten means it heats and melts the pieces faster, allowing you to achieve proper fusion without overheating the entire piece.
Keep the tungsten tip sharp to focus an arc on a small area. A focused arc yields a narrow HAZ, reducing the risk of warping or distortion.
Sharpened tungsten tip for a focused arc.
Source: https://www.youtube.com/shorts/apDU-T9xaFg
3. Choose the right filler rod for thin steel
As noted, TIG welding thin sheets requires a tight fit-up. Although you can weld extremely thin pieces without filler (autogenous welding), most welders recommend using a small-diameter rod for 18-gauge steel and thinner.
The first step is to match the composition of the TIG rod to the base metal. For most mild steel welding, you will need an ER70S-6 rod. These are general-purpose mild steel rods that cover most applications.
YesWelder ER70S-6-5LB Mild Steel TIG Welding Rod
What matters more is the rod's diameter. The thinner the rod is, the less heat it needs to melt. Also, it will provide a limited amount of filler metal, which is crucial when working with thin metal and smaller gaps.
Depending on the metal thickness, you will need 1/16" or .045" TIG rods. These are small enough to provide enough filler without overheating the joint.
But, keep in mind that most commercially available TIG rods for steel don't go below .045". In extreme cases, for delicate work and super-thin steel, you can use a MIG wire as a filler.
ER70S-6 rods and MIG wires have similar composition, but the wires go down to 0.023". So, you can cut and straighten a piece of MIG wire and feed it as a TIG rod.
Straighten MIG Wire for TIG Welding
Photo by @vanthefabricator (TikTok)
4. Use more tack welds on thin metals
Tacking the welds is a common practice in welding and helps keep everything in place and aligned. But when welding thin metal, using a few tacks can cause the sheets to pull apart, leaving a gap.
Close-Up TIG Tack Welds on Thin Metal
Photo by @vanthefabricator (TikTok)
The good practice when TIG welding thin steel is to use more tacks than you normally would. By adding tacks every 2-4", you prevent sheets from pulling apart between two tacks.
Although mild steel doesn't warp and distort as much as stainless steel or aluminum, any sheet metal is prone to warping. Using multiple tacks can be time-consuming, but it is much safer.
When making tack welds on thin metal, use as little filler as possible, or none at all. Aim for fusion welds because you can weld over them later. Doing so will save you time and won't affect the weld structure. If some warpage occurs, you can always hammer it down before starting to weld.
TIG Tack Welding 1mm Thin Tube to 1mm Thin Sheet
Source: https://www.youtube.com/watch?v=BY7CrAlWFi4&t
5. Adjust parameters and controls for thin steel
TIG welding is a perfect choice for thin steel because it produces less heat and can work at low amps. Dialing in your TIG welder mostly depends on the thickness of the metal you are welding.
Metal thickness dictates the tungsten and filler diameters, so you can get it wrong. For example, 1/16" thick steel requires a 1/16" rod and tungsten, which work best up to 50A. Reference charts will help you get started, and you can always tweak parameters the way you like them.
TIG Welding Vertical-Up T-Joint Weave on 1/16” Mild Steel
Photo by @hoodedweld (TikTok)
Inverter TIG machines allow you to control the entire process: start amps, upslope, base amps, downslope, and end amps. Mild steel isn't very heat-sensitive, so you won't need to tweak everything. You can adjust the start and end amps to prevent overheating metals right away, and fill the crater properly at the end.
One feature that can greatly help you with thin-sheet welding is pulsed TIG. In pulsed TIG, the current alternates between peak and background amperage at the given rate (Hz). Doing so reduces overall heat exposure, which is critical in sheet welding. You can find it with the YesWelder TIG-200P AC/DC welder, which makes welding thin metal very suitable.
TIG-200P-ACDC-PRO AC/DC Aluminum TIG Welder
6. Control and observe the heat
TIG welding supports remote amperage control via foot pedal or torch. The ability to control amperage while welding will significantly help you weld thin metals.
By observing the puddle and weld, you can tell if you are running hot or cold. If you start blowing through the welds or the metal starts to distort, you are likely going too hot. If you see a lack of fusion and poor fluidity in the puddle, you are likely running too cold.
A torch amperage control or foot pedal will help you make adjustments on the fly. Most new TIG welders support remote controls, so don't be afraid to use them. But, if the welds get too hot, it is always better to stop rather than risk other defects.
TIG Welding Sheet Metal Using a Foot Pedal
Source: https://www.youtube.com/watch?v=2-6ShkZUj9k
7. Adjust your technique and take breaks if needed
When TIG welding thin steel, pay attention to the amperage/travel speed ratio. As noted, smaller-diameter consumables require less current, reducing the risk of overheating. But, they also take time to melt, which can broaden the HAZ and warp the pieces.
Since mild steel has lower thermal conductivity than aluminum, you can get away with slightly larger consumables. Although they need more amps, you can travel faster, reducing the risk of heat build-up, while retaining proper fusion.
Keep the arc tight to concentrate the heat into the joint. Tight arc narrows the HAZ, reducing the risk of warping and distortion. The only downside is that you can accidentally touch the tungsten to the weld and contaminate both.
Keep the arc tight for focused heat when TIG welding thin metal.
Source: https://www.youtube.com/watch?v=ppvu8KGh6PM&t
8. Consider using stitch welds on thin sheets
If you notice excessive distortion and warping, consider using stitch welds. Instead of running a single, long bead that can overheat the sheets, make a series of short, intermittent welds along the joint.
Simply put, start at one end, make a short weld, then stop and start from the other end. Rince and repeat until you meet in the middle. When restarting the welds, move 3/16 inch back along the top of the previous weld. Body-hammer or dolly out any warpage to flatten the back of your metal.
However, if you are confident enough, you can get away with longer welds on thin steel using TIG. TIG's limited heat and mild steel's forgiving properties often allow you to weld longer.
TIG Welding Thin Aluminum Sheets
Source: https://www.youtube.com/watch?v=P9HPvW9BrUw&t
9. Consider using a heat sink
If you feel like you can't control the heat, and metals warp no matter what you do, consider using a copper or aluminum backing bar. Although warping shouldn't be as severe as with aluminum or stainless steel, a heat sink can always help when TIG welding sheet steel.
In welding, a heat sink is a backing bar made of copper or aluminum. You clamp it at the back of the weld to absorb excessive heat. Aluminum and copper have high thermal conductivity, so they dissipate heat from the joint.
Copper has higher thermal conductivity, but aluminum bars are generally less expensive. Regardless of the choice, both can help if you often experience warping and distortion during thin-metal welding.
Use heat sinks to prevent warping when TIG welding thin metal.
Source: https://www.youtube.com/shorts/E38rpA-tLBQ
10. Fix the burn-throughs
Burn-throughs happen on thin metal, even to more experienced welders. The good news is that you can fix smaller holes by refilling them.
Burn-through occurs when TIG welding aluminum.
Source: https://www.youtube.com/watch?v=2EqCFF-D5E8&t
To fill the burn-through hole with TIG welding, start at the edges and dab the filler in circles toward the center until you fill the middle. Moving in a circle ensures you are melting into all the edges, avoiding the air pockets.
If the center caves in, add more filler to make it flush, flip the piece, and heat it from the back. Once you get a proper fusion, grind the surface to make it flush with the rest of the metal.
Use a flap wheel to clean up the weld after fixing the burn-through.
Source: https://www.youtube.com/watch?v=2eClIo9aik8&t
Final Thoughts
TIG welding is an ideal method for welding thin metal. Its heat control and cleanliness are ideal for steel, stainless steel, aluminum, and other sheet metals.
However, as forgiving as it can be, TIG welding thin steel still takes some time, practice, and patience. But as long as you understand the overheating issues and know how to address them, you are set for success.
TIG Welding on Thin Steel
Photo by @kuntzfabrication (TikTok)
🧐 TIG Welding Thin Steel: Techniques, Tips & Tricks FAQ
1. Can you TIG weld thin steel?
Yes. TIG welding is one of the best methods for thin steel because it offers precise arc control, low-amperage welding, and cleaner welds with less heat input.
2. What tungsten size is best for thin steel?
A 1/16" or 3/32" tungsten is a good starting point. A smaller tungsten creates a tighter arc, while a slightly larger one can help you move faster and reduce heat buildup.
3. How can you reduce warping on thin sheet metal?
Clamp the pieces tightly, use more tack welds, control heat input, and let the metal cool between passes. Stitch welding can also help prevent too much heat from building up in one area.
👏 You may be interested in the following:
- How To Shape Tungsten Electrode For TIG Welding And Why?
- How To Setup A TIG Welder For First Use
- How To TIG Weld
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