How To TIG Weld Different Thickness Metals

TIG welding is one of the most challenging processes to master, but with enough time put into practice, it yields the highest quality, clean, and good-looking welds.

However, due to the somewhat higher skill required compared to Stick or MIG welding, many beginners ask how to tig weld different thickness metal.

That's why we decided to compile this comprehensive article, where we will help you understand how TIG welding deals with a thin metal, medium-thickness, or hobbyist metal and thick stock.

Photo by @ss_custom_welding (TikTok)

TIG Welding And Different Thickness Metal

Gas Tungsten Arc Welding (GTAW), also known as TIG welding processes, utilizes a non-consumable tungsten electrode to form a welding arc. The welding arc heats the base metal, and two pieces join either by fusing (autogenous welding) or with added filler metal.

Regarding metal types and different thicknesses, TIG welding is one of the best welding processes for thin metal and "exotic" metals such as aluminum or magnesium. However, as the thickness increases, TIG welding falls slightly behind due to slower deposition rates and the high skill cap required.

Nonetheless, TIG welding still deals well with medium-thickness mild steel and thick stock, and further in the text, we will explain how. So, let's see how and what you need to TIG weld different thicknesses.

TIG Welding Thin Metal

TIG welding is often a go-to method when projects include welding thinner material or delicate metal. The sole reason is exceptional control over the heat input and the entire welding process, from the start to the end. Controlling the heat prevents common issues when welding thinner metal, such as burn-through, discoloration, wrapping, and distortion.

The best part about TIG welding thin metal is that there are almost no boundaries. Over the years, the method was taken to the next level, allowing welders to weld metal that is even 0.0002 square inches thick. Nevertheless, in this section, we will talk about welding sheet metal you are likely to encounter in your shop or garage, commonly going down to 24-26 ga.

Stainless Steel TIG Welding 26 ga

Source: https://www.youtube.com/watch?v=Fp1C95ZPULo

If you are unsure about the thickness of your metal, you can always use a helpful YesWelder welding gauge tool. To TIG weld thin metal, you will need appropriate equipment, good preparation, and suitable equipment. We will explain how each can affect your results with sheet metal.

LG-03 Stainless Steel Welding Gauge

TIG Welder For Thinner Material

TIG welders for thinner metal must have certain features such as squarewave pulse, AC input, and AC balance, as well as fine controls, including starting amps, upslope, downslope amperage, and post flow. In addition, if you want to weld extremely thin metal, the lowest output should be approximately 5-10 amps.

Our all-around recommendation for thin metal is the TIG-205P DC Pulsed TIG Welder, a 5-250 amp rated TIG welder you can use for <25/64" aluminum, stainless steel, and <15/64" brass. The best part is that you get all the mentioned features for a more than reasonable price. So let's explain how these will help you weld thin metal.

TIG-205P DC Pulsed TIG Welder

Pulsed TIG is a must-have welder feature if you want to weld thin steel or delicate metals such as aluminum, stainless steel, and non-ferrous metals such as magnesium and copper alloys. Introducing a pulse limits and controls the heat, which is crucial. The heat of the arc pulsates, so you don't have to worry about burning holes, wrapping, or distortion.

TIG-250P welder also supports an AC current input, which is crucial when welding aluminum. The electrons in the AC constantly alternate between positive and negative polarity, which results in limited heat and penetration. Advanced welders, including TIG-250P, allow you to adjust the number of pulses per second, to provide just enough heat, as well as the balance between cleaning and penetration.

You can also consider YesWelder YWT-200DC TIG welder if your projects include something other than aluminum welding. This welder also has everything you need to weld sheet metal, with added cold spot TIG feature that reduces the overall heat and risk of discoloration. However, this is a DC-only welder, meaning you won't be able to weld aluminum.

YWT-200DC Lift TIG Spot TIG Welder

Tungsten For Thin Metal

When dealing with thinner metal, you will need to choose smaller-diameter tungsten and filler metal. Using inappropriate size tungsten or consumables will extend the heat-affected zone, leading to common defects.

For thinner metal, you should use tungsten sizes up to 3/32 inches. Micro-TIG applications on delicate metal will require a .020, .040, or 1/16-inch tungsten, but as a beginner, you can start with 3/32 and work your way down. Smaller-diameter tungsten performs well on low-amp applications, and its size limits the heat-affected zone.

For beginners who commonly weld mild steel, we recommend 1.5% Lanthanated Tungsten from YesWelder. This is a versatile choice for any metal, and it works great with both AC and DC input. However, the tungsten type can be a piece of personal preference, so you can also opt for Ceriated or Thoriated tungsten.

WL15 Series 1.5% Lanthanated TIG Welding Tungsten Electrode 

Regardless of type, tungsten for the thinner piece should be an appropriate size and pointed. You should always sharpen the tungsten to focus an arc on a small area of mild or stainless steel. However, TIG welding aluminum will require a balled or flattened point. You can prepare your tungsten with a simple YesWelder tungsten electrode sharpener.

TTG02 Tungsten Electrode Sharpener Grinder

Filler Metal For Thin Metal

In extremely delicate work and Micro-TIG, you won't have to use a TIG filler metal, as it would be too large to fit the micro joint. However, as a hobbyist and beginner welding down to 24 ga, you will need a filler rod.

As a rule of thumb, a larger rod takes more heat to melt, and you want to avoid that with a thinner part. Therefore, welding 24 ga to 1/8" thick metal will require a 0.045-3/32 size filler rod. A good practice is always to match the size of the tungsten and filler rod to the metal you are about to weld.

In addition, you will have to match the composition of the TIG rod to the base metal. For example, ordinary mild steel will require an AWS ER70S-6 rod. On the other hand, 304 stainless steel is a widely spread grade, and the go-to rod should match AWS ER308 & ER308L classification. Hobby and everyday grade aluminum is commonly welded with AWS ER4043 TIG welding rod.

Welder Settings And Control

To get the best settings for TIG welding thinner parts, you will need to follow the manufacturer's recommendations, but many different options will help. The control panel of a good TIG welder can look like a control board of a spaceship for beginners, but once you get the hang of them, you can completely control the welding process.

Welding sheet metal will require setting a pulse frequency, commonly in the range of 0.5 Hz-200 Hz. As we noted, adjusting the pulse will limit the heat, yielding strong and good-looking TIG welds. However, TIG welders allow you to set more than just a pulse.

Inputting a low starting amperage will prevent delicate metals with high thermal conductivity from instantly melting or wrapping once you start welding. Next, you can set the ramp-up amperage, where the welder gradually reaches selected amps. After you are finished welding, downslope amperage and end amps will ensure the weld joint is adequately filled and the weld pool continues to the end of the joint. Finally, post-flow will cool down the torch, extending the life of consumables.

The foot pedal will help you a lot in tweaking the amperage during welding, and all modern TIG welders, including YesWelder TIG-250P AC/DC, are compatible and equipped. With a pedal, you can adjust the heat on the fly, which is crucial if you notice something goes wrong during welding. DCEN polarity is the most common choice for TIG welding when the cleaning action of the DCEP process is not needed.

FP-5P-B TIG Amperage Control 5-Pin Foot Pedal

As you can deduce, each of these settings plays a crucial role in controlling the heat while maintaining stable arc length and getting the best results. Even though it will take time, mastering your TIG welder controls will yield the best results.

Shielding The Puddle

TIG welding almost always utilizes pure Argon shielding regardless of the material thickness. In industrial or specific applications, Helium or Hydrogen can be added. Inert gases protect the weld pool from defects and are a must-have for any successful TIG welding operation.

 Pure Argon Shielding Gas

Photo by Emilian Robert Vicol on Pixabay

As a shielding gas, Helium produces higher penetration and heat but also increases the welding speed. However, it is expensive, and you want to avoid extra heat when dealing with sheets. Hydrogen or Nitrogen is used in 2-5% addition to Argon to weld duplex, super duplex, austenitic stainless steels, and copper.

You will likely use 100% argon as a hobbyist due to lower costs and decent results on various metal thicknesses. However, with extra thin sheets, you should also shield the back side to avoid contamination. In addition, for better shielding gas coverage, you should use a larger #15 TIG cup and gas lens kit. That way, you provide extra protection for delicate and exotic metals.

TIG stainless steel pipe welding with argon gas flow 10-15ml

Photo by @welding_cyl (TikTok)

Weld Preparation And Welding Technique

Proper weld preparation will save you hours of post-weld work. Cleanliness is crucial, like in any welding process, and TIG is not so fond of dirt, rust, paint, or oil. You want an excellent fit-up with low to no gap at all with thin metal. Before you start welding, you can clamp everything in place and start with multiple tack welds to keep it in place.

Due to the limited heat input of TIG welding, you can go for longer weld welds. Meanwhile, in MIG welding, you should occasionally stop and do stitch welds to prevent heat buildup. Finally, you can weld entire car panels in a single run if you feel comfortable with your technique.

However, it takes a lot of time and practice to master the weld and dub technique with TIG. Nonetheless, you can weld sheet metal significantly faster and with higher quality results and weld appearance.

You can add the backing bar if you feel like you can't control the heat, which is rare with TIG welding. The copper backing bar will act as a heat sink absorbing the heat and allowing pieces to cool down more quickly.

Backing bar used to draw heat away from the weld and prevent distortion

Source: https://weldguru.com/tig-welding-stainless-steel/

TIG Welding Medium Thickness Metal

TIG welding can successfully be employed to weld medium-thickness metal, commonly referred to as hobbyist metals. By that term, we consider plates up to 1/2" thick you are likely to encounter in your garage or small welding shop.

Even though this is yet another process with good penetration, TIG requires higher skill and is slower than MIG or Stick welding. That's why there are more suitable welding process choices for the hobby work of complete beginners. However, TIG may become your go-to method once you understand the fundamentals and get enough practice.

Since welding medium-thickness plates is much more forgiving than sheets, this section is somewhat shorter. Nonetheless, we will explain it as thoroughly as possible.

TIG welder for Medium Thickness Metal

While TIG welding sheets require many features and a low amp TIG start of 5-10 amps, welding thicker material up to 1/2" is much easier. Therefore, you will be perfectly fine with a DC-TIG welder rated at 200-250 amps. Our recommendation is certainly YesWelder YWT-200DC TIG Welder.

YWT-200DC Lift TIG Spot TIG Welder

This welder offers a perfect combination of features and power for everyday steelwork. It is a DC-only machine, meaning you cannot TIG weld aluminum, but with a high-frequency start, features such as pulse, and different controls. As a result, you can use it to weld various thicknesses of steel, including thinner and thicker metal up to 1/4".

TIG welders for hobbyist metal can have advanced controls such as upslope and downslope, start or peak amperage, but it is optional. However, these can help you master welding both thinner and thicker pieces, so it is always a good thing to have.

Tungsten And Filler Rod Choice

As the thickness of the metal increases, you will need to use larger-size tungsten and filler rod. Novice welders can also start with 3/32 inch 2% Lanthanated tungsten (even though many "old school" welders prefer Thoriated tungsten) and work their way up as the thickness increases. Once the base metal thickness starts getting over 1/8" up to 1/4", you need to use 3/32 up to 5/32 tungsten. 

You should pair your tungsten with a #7 TIG cup, which is standard for medium plates. Welding steel will require a sharp tungsten tip, like with thinner materials. 

The good part about TIG welding medium-thickness steel is that you have a lot more room to experiment with tungsten and filler sizes, as well as welding parameters. Nonetheless, you will still have to match the composition and size of the tungsten and filler rod to the thickness and type of the metal. AWS classifies the composition of the filler, and we covered it in the thin metal section of the article.

Welder Settings and Parameters

A thicker piece will also require a thicker TIG rod. As a guideline, TIG filler should be at least one size smaller than metal thickness. For example, a 1/4" rod suits 1/2" metal, a 3/16 rod fits 1/4" metal, while a 1/8" rod works with 3/16" thick metal. 

To weld medium-thickness metal, you won't t need too many special settings or features, but you still have to adjust the amperage and gas flow. 250-amp-rated TIG welders, including YesWelder TIG-250P, will handle most hobbyist mild steel up to 1/4" in a single pass. However, you should always follow the manufacturer's recommendations for precise settings.

Adjusting starting amps, upslope or downslope with medium-thick steel is optional, but you can use it for the best results with specific metals such as aluminum and stainless steel. In addition, a foot pedal control can help you while learning, as you can add more heat or reduce it if you feel your starting parameters are incorrect. Finally, post-flow will prolong the life of your torch, electrode, and consumables, but it might waste some extra gas.

Once again, there is much more room to experiment with a thicker plate than a thinner part. However, if you start burning through metal, reduce the heat, and if you struggle to maintain the arc, increase it.

Compared to thinner sheets, with medium plates, you can add some helium to stabilize the arc and increase penetration. Thicker metal can handle the heat and penetration that this gas offers. Like with sheet metal, DCEN (electrode negative) will provide better results than DCEP (electrode positive).

Weld Preparation And Technique

Compared to MIG welding different thickness metal, TIG welding medium-thickness metal will still require good preparation and precise welding technique. Base metal should be cleaned appropriately as any contaminants can cause weld defects such as porosity or inclusions, eventually leading to cracking. You can use more designs than sheet metal as you are not limited to butt joints or lap joints.

GTAW requires working with both hands, and that's where it can get complicated for beginners. In addition, you will need some time to coordinate moving the torch and dipping the filler, as you won't be able to use fusion (autogenous) welding to fill the gap between thicker plates.

Overall, TIG welding metal up to 1/2" is pretty forgiving and straightforward, but lower deposition and higher skill requirements make MIG welding a more popular method for the same thickness.

TIG Welding Thick metal

Once the thickness of the metal surpasses 1/2", TIG welding is not so economical and a common choice. While there are powerful machines that can handle thick stock, filling significantly larger gaps takes a lot of time and effort, so many welders choose Stick or Flux core welding for thick pieces.

Nonetheless, certain applications require cleanliness and high quality of the weld metal and weld area. These include welding pipes that carry oil, gas, or water, where welds must be of the highest quality.

Still, due to slow speeds and high costs, TIG is used for the first bead or root pass, while the rest of the gap is filled with stick, flux core, or dual shielded flux core techniques. Here is a quick explanation of how TIG works in welding root beads.

TIG For Thick Weld Metal

To weld thick pieces of pipe or plates, you won't need a super high-rated TIG machine. Instead, you can do it with your regular 250 amp welder, but as long as you ensure adequate preparation and use multiple passes. In addition, pieces must be beveled, ground, and free of mill scale.

By beveling two pieces of thick metal, you can make a 1/16" to 1/8 gap in a 2" pipe. The gap is significantly smaller than the entire thickness of the stock, so you take an approach like when welding 1/16 or 1/8" pieces. That means you don't need to use the full power of the machine, as approximately 100 amps will be enough. In addition, filler rod size is also moderate and, according to the size of the gap, commonly up to 1/8".

When welding thick pieces with a single-pass approach, you will need a welder rated more than 300 amps with 1-3 phase input and a big, water-cooled TIG torch. These are commonly heavy-duty, massive industrial-grade machines that provide more volts and more amps.

However, buying these is not cost-efficient as a beginner or hobbyist, so you should stick to multi-pass welding and a small TIG machine.

Technique For TIG Root Pass

The technique for TIG welding the first pass in the thicker piece is somewhat more challenging compared to sheet metal and medium-thickness plates. You would have to learn how to walk a cup.

After preparing and tacking pieces, welders lay down the filler across the gap, while some use smaller diameter rods to feed it through the inside of the pipe. Next, you should lay your cup on the opening and "walk" it left and right across the gap, melting the filler and filling the weld. Shielding the weld area is essential, but you should also provide back protection like with thin sheets.

TIG welding root pass requires a lot of practice and is significantly harder than shielded metal arc welding. However, pipe welders who are familiar with the technique will be fine finding a job.

Final Thoughts

TIG welding is one of the best methods for thin and delicate work, as it offers excellent control over the entire welding process. It results in high-quality, clean, hygienic, and aesthetic welds, but you will need a lot of practice to get there.

Welding medium-thickness plates with GTAW is much more forgiving and easier, but still, many choose MIG or Stick welding due to lower skill requirements. TIG is commonly used for root, first or initial pass in thick pieces. Even though there are heavy-duty welders, many choose other methods for thick stock due to higher welding speed and lower costs. 

1. How to choose tungsten and filler metal for thin metal in TIG welding?