How to Set Up a TIG Welder for Mild Steel


If you’ve gotten interested in TIG welding lately, then you probably know that TIG welding is a complicated process to learn. However, it’s also gratifying, and once you get the hang of it, you’ll be creating beautiful metal workpieces in no time at all. Part of learning the process of TIG welding means you’ll need to learn how to set up a TIG welder for mild steel.

So, how do you set up a TIG welder for mild steel? When learning how to TIG weld with mild steel, you will need to take extra time and practice to learn the skill, but you’ll be using Tungsten and Argon gas, just like when you weld most other metals. You will need better gas coverage than what you’ll need when welding other metals, however. You’ll also need to learn the TIG power supply features and TIG welding machine settings. 

Since there isn’t a lot of information on the Internet today discussing how to set up a TIG welder for mild steel, we created this article to save you some time. To help you understand how to set up a TIG welder for mild steel, we’ll cover how TIG welding works on mild steel, the TIG power supplies you’ll need, the TIG torch options for welding mild steel, how to set-up your electrode for mild steel, and how you’ll set-up your TIG welding machine for mild steel.

TIG Welding and Mild Steel

If you’ve already started the process of learning how to TIG weld, then you know that one of the reasons it’s so challenging to learn TIG welding skills is because you use two hands in TIG welding. Plus, TIG is a bit different when compared to other welding processes for steel because of how we create the arc and add the filler material during TIG welding differs.

You need to use two hands when TIG welding because one hand uses the TIG torch that creates the arc, and your other hand adds the filler metal as you are welding joints (a feeder pen can be immensely helpful, especially for beginners and infrequent welders). Since TIG welding means you’ll have to get used to using both your hands at once as you weld, it’s one of the most challenging welding processes to learn. However, when it comes to welding things like mild steel, TIG welding is also very versatile.

While the TIG welding process might also feel slow when compared to other welding options out there, once you learn how to TIG weld, you probably won’t want to stop. That’s because TIG welding creates the best-looking welds around. We find TIG welding often used for welding critical joints, welding a variety of metals including mild steel, and TIG welding also works well for small metal areas.

Using Tungsten to Weld Mild Steel

So, we’ve mentioned “tungsten” often above, and now we’d like to break it down a bit so that you understand why Tungsten works so well when welding mild steel. Tungsten is the item that gives us TIG welding because, without it, we wouldn’t have TIG welding.

Tungsten is a brittle, hard, somewhat radioactive metal. When you compare Tungsten to other metals, it has a limited use factor. However, it works very well in TIG welding because TIG welding uses Tungsten to create a non-consumable electrode, which also makes our arc in TIG welding. You’ll also find Tungsten used in things like rocket engines, heaters, and light bulbs.

TIG welding and tungsten metal work so well when welding mild steel because the Tungsten keeps the arc with a consistent temperature of 11,000 degrees F. Tungsten brings us a high melting point, and also offers excellent electrical conductivity as you weld, so the tungsten electrode won’t ever burn up.

Tungsten’s unique properties as a metal allow us to make a hotter arc than what we find with the actual melting point of Tungsten. Tungsten’s tensile strength can go up to 500,000 lbs per square inch. Steel, on the other hand, has 36,000 pounds of tensile strength per inch. So, you can see by this comparison why Tungsten works so well on steel when welding

How TIG Welding Works on Mild Steel

When you are TIG welding with mild steel or any other metal for that matter, you need to have three things. Those three things are heat, shielding, and filler metal. You’ll get the first item, temperature, which is made because electricity goes through the tungsten electrode, creating an arc for you to work with on your project. The second item, shielding, means you’ll need a compressed bottle of gas going into the weld area, and you’ll have to protect that gas from the air. The last item, filler metal, comes from a wire you dip into the arc and melt.

When you are TIG welding, you are trying to bring all three of these things together to create one fantastic, finished final project. We start with the welder turning on the gas flow, which you can usually control using a valve that’s on the TIG torch. Once you’ve done that, you’ll see gas start flowing, which is created to keep the weld area safe from the air. You then take the torch and hold it over the weld joint without touching the metal.

After that, you’ll press a good pedal, and that will start the tungsten electrode’s arc in the TIG torch. Once you’ve created the arc, you’ll see the two pieces of metal will begin to melt and form a puddle of liquid metal. Once you’ve developed your pool, you’ll use your other hand and fill the joint. That means dipping a wielding wire into the arc is so that you can fill the joint. After that, you will have formed one piece of metal.

Now that you understand how TIG welding works on mild steel, we’ll cover some TIG welder power supplies you’ll want to consider when TIG welding with mild steel.

TIG Welder Power Supplies for Mild Steel

When we’re talking about TIG welding power supplies for mild steel, we’re talking about the same things you’ll use for Stick welding power supplies. However, there is a significant difference between a Stick welding power supply and a TIG power supply, and that’s the additional features you’ll find on the TIG welder that allows your torch to TIG weld correctly.

For example, you can use your usual TIG torch on your Stick welding power supply, and you’ll do just fine welding. Both power supplies, the TIG torch, and the Stick welding power supply allow for constant amperage, which is what you’ll need when working with steel. They both help keep the amp rate consistent, and that regulates the heat produced. How much voltage you’ll need will depend on how long your arc is.

Now that we’ve talked about the power supplies you’ll need to know about when TIG welding mild steel, we’ll discuss some of the extra features you’ll find on a TIG power supply versus what you’ll find on regular power supplies when welding mild steel.

Feature #1: TIG High-Frequency Start

Most types of TIG power supplies offer something called a “high-frequency start.” Having a high-frequency start option on a TIG power supply is terrific because you won’t need to physically strike an arc with one of these. Instead, once you use the high-frequency start option on your TIG torch, it will make an arc over a one-inch gap between the metal and the torch. The torch does this by using a quick moment of high voltage with the pressure to help the arc form.

Once you’ve used the “high-frequency start” to form the arc, the voltage starts dropping, and the amps will take over. Having this feature is hugely beneficial because it prevents the Tungsten you are using from getting contaminated. So, you won’t wind up using your Tungsten up as quickly. You’ll also experience less wear and tear on your tungsten electrode over time. That means you’ll have plenty of Tungsten to use while welding your mild steel.

Feature #2: TIG Shielding Gas Pre-Flow and Post-Flow

Other additional features you’ll find on TIG welding power supplies include the pre-flow and post-flow features. You’ll use the pre-flow feature when you want to allow some pre-flow time for your shielding gas to create a shield before you form your arc. On the other hand, the post-flow feature helps keep the gas going for a predetermined time once the arc stops so that the weld is safe until it cools. Since both of these features help keep you safe while welding mild steel, you’ll probably be using them. To make sure gas is properly flowing before welding, a shielding-gas gauge is very handy.

The two most common gases welders use as shielding gases are Argon and Helium. Both of these gasses are Nobel inert gasses, meaning we use them because they don’t alter the characteristics of the weld joint at all.

Some welders like using a mixture of Argon and hydrogen or a combination of Argon and nitrogen. However, when dealing with mild steel, it’s recommended that you use Argon.

Feature #3: AC Waveforms Controls

Another feature you’ll find on your TIG welding power supply is frequency settings. Using these settings, you’ll be able to adjust what you want to see in your welding arc. There are several methods you can use to keep your welding arc running smoothly. With the frequency settings, you can use frequency ranges and other pulses of electricity to modify the arc, so you get what you want. While these settings are essential to know about, you probably won’t be using them often with steel. You’ll more likely use then when welding aluminum or magnesium.

Now, if you don’t have a TIG welder, but you have a stick welder, you can convert your stick welder into a TIG welder for mild steel if you’d like. It’s prevalent for welders to do this. If you’re thinking about converting a stick welder into a TIG welder for mild steel, we’ve got the steps for you below.

Convert a Stick Welder into a TIG Welder for Mild Steel

In the welding world, you’ll frequently find experts using stick welder to TIG weld either carbon or steel pipes. In some cases, welding experts feel that Stick welding supplies perform better than TIG welding power supplies when you are working with mild steel wall pipe.

It’s effortless to convert a Stick welder for TIG welding. All you’ll need is an air-cooled TIG torch and an extra bottle of Argon. After that, you’ll need to follow the steps below:

  • Swap the polarity to D/C Electrode and negative.
  • Grab an air-cooled TIG torch. Next, attach it to the electrode holder.
  • Last, grab your gas supply hose. Hook that hose up to a regulator on one of your bottles of Argon.

Once you’ve completed these steps, you’ve successfully converted your stick welder into a TIG welder.

Now that you understand how to convert your stick welder into a TIG welder, we’ll discuss the voltage types and welding polarities you’ll need to use when welding mild steel.

TIG Welding Voltage Type and Welding Polarities for Mild Steel

When it comes to TIG welding, you’ll find that the same voltage types are used for Stick welding when working on mild steel. Your two voltage types include Direct Current, D/C, and Alternating Current, or AC. D/C Current operates much like a car battery does, and can only flow one way. That one way moves from the negative to the positive. On the other hand, alternating current is also available, and that’s much like the current you’ll find in your own home. A/C can change its current direction several times over a second when needed.

Furthermore, you’ll also discover that TIG welding also uses two polarity types, much like Stick welding, when it comes to utilizing direct current. Those two polarity types include the DC, or Direct Current Electrode Negative, which means the electrode or welding handle is switched to the negative on the circuit, and the electricity goes from the TIG torch to the metal. The DC or Direct Current Electrode Positive means that the electrode or welding handle is switched to the positive circuit, so the electricity flows from the metal to the TIG torch.

The differences in polarity affect how much heat you’ll be applying to the electrode. With D/C Electrode Negative, you’ll get about 66% of the heat in the metal welded. That means you can create a deep penetration weld with this feature. On the other hand, the D/C electrode positive places about 66% of the heat onto the electrode. You’ll be able to complete a shallow weld this way. So, whether you want a deep weld or a shallow weld, you’ll be able to easily use these welding polarities to help you weld mild steel successfully.

How DC TIG Welding Polarity Works for Mild Steel

If you want to comprehend how DC works with mild steel, think about the way water moves. If you grab some water out of the fridge and place it in a glass, the glass getting the water feels the friction. So, the water pitcher in the refrigerator can be considered the negative end, which is giving up the water, and the glass can be looked at as the positive side that is gaining the water. The side getting the water will always be the side with the most friction.

 In welding, instead of focusing on who is gaining water, we focus on the side of the heat that’s most concentrated when working with sheet metal. So, D/C power works with heat in welding the same way it does when you move water from a pitcher to a glass. It’s all about friction.

Now that you understand how DC TIG welding polarity works for mild steel, we’ll cover TIG torch types for mild steel, and we’ll move onto the TIG welding machine set-up for working with mild steel.

TIG Torch Types for Mild Steel

If you’ve decided you want to pick out your TIG torch rather than convert one, that’s not a problem. You have two options when it comes to picking out a TIG torch for mild steel. You can select either air-cooled TIG torches or water-cooled TIG torches. We’ll discuss both options in a little more detail below.

Air-Cooled TIG Torches for Mild Steel

If you’re shopping on a budget and you want something affordable and practical for working with mild steel, then air-cooled TIG torch might be your best bet. However, air-cooled TIG torches do have their drawbacks. These torches heat a lot, and part of the problem you’ll notice is that the heat produced by the arc is often wasted. The handle will start feeling hot to the touch after ten to fifteen minutes of welding, meaning you’ll have to stop and take breaks from time to time if you opt for an air-cooled TIG torch for mild steel. 

However, if the idea of an air-cooled TIG torch isn’t for you, don’t worry. You do have another option, although it will likely cost you a bit more. However, it might be the better one of the two options for you, depending on precisely what you need. 

Water Cooled TIG Torches for Mild Steel

If the first option doesn’t seem right for you, then you can also consider a water-cooled torch to weld mild steel. You’ll wind up with an excellent torch that’s very efficient if you go this route. However, getting this type of torch means you’ll have extra maintenance, and you’ll also have to purchase a TIG torch water cooler along with the torch, too. 

TIG Torch Water Coolers for Mild Steel

Anytime you use water-cooled TIG torch, then you’ll be required to have a water cooler, too. With this type of torch, the water cooler cools your TIG torch. You’ll find a radiator inside of the water cooler, just as you would in a car, that passes water through it, and a fan blows into it to help cool down the water. 

If you can afford it, we’d highly recommend getting the water-cooled TIG torch with a water cooler. You’ll wind up saving money over time because the product is more efficient, and you’ll also be able to weld for more extended periods without stopping.

Now that you understand your options in TIG torches, we’ll cover the TIG welding machine set-up for welding mild steel. 

TIG Welding Machine Set-Up for Mild Steel

You’ll discover two main settings when you start setting up your TIG welding machine for mild steel. Those two settings include gas flow and amperage. You’ll likely vary your amperage settings based on how thick the metal you plan to weld appears. You’ll want to set the amperage to a comfortable area and see how fast it melts the metal into your welding. You can adjust it as you see fit, but you might want to play around at first to figure out where you want the amperage to be before you get started on your mild steel welding project.

On the other hand, you’ll also need to set the gas flow rate. You’ll need to vary the gas flow rate up now and then based on your cup size, draft conditions, and how you are welding. If you have a larger cup and you’re working when it’s windy, you can use a gas rate between 5 CFH to 60 CFH. When you are welding mild steel and picking a gas to weld with, the gas you’ll most likely always use is pure Argon.

Below we’ve included a list that has guidelines for your machine set-up when welding mild steel.

  • 1/16 Tungsten means you’ll need amps between 50-100, cup sizes of 4, 5, or 6, and a gas flow rate of 5-15 CFH.
  • 3/32 Tungsten means you’ll need amps between 80-130, cup sizes of 6, 7, or 8, and a gas flow rate of 8-20 CFH.
  • 1/8 Tungsten means you’ll need an amperage rate between 90 to 250, cup sizes of 6, 7, or 8, and a gas flow rate of 8 to 25 CFH.

TIG Welding Mild Steel

When TIG welding mild steel, you’ll want to use a DCEN (direct current electrode negative) polarity, Argon gas, and Thorium Tungsten. You’ll need to keep in mind when you weld any steel that you’ll have to shape the Tungsten to a fine point.

Welding steel is very similar to welding other types of materials. However, it does typically take people longer to learn how to weld steel, so expect there to be some practice time for experimentation as you are learning how to do this. The one thing that is very different about welding steel is the amount of good gas coverage you’ll need.

Sometimes when you are welding steel, you need to put your weld in an Argon bath or purge it with a filler gas, which is something different you’ll need to learn, and you’ll need to take some practice time out to do it. Not only that, but many people require more time to learn how to weld steel because steel has a bad habit of warping when too much heat is applied. When that happens, welds won’t brace and hold correctly, and you’ll wind up with distorted metal.

Now, if you run into some distortion while welding mild steel, you can control that by staggering your welds and bracing your weld area as often as possible.

Sanding Disk for Cleaning Mild Steel

Keep in mind that joint preparation is an essential part of TIG welding with mild steel. You’ll need to make sure the joint is very clean before you start your weld. If you don’t do this correctly, you’ll notice the filler wire isn’t flowing right into the joint. When you are welding on a mild steel joint that isn’t clean, the filler wire won’t stick totally to all of the areas of the joint. Since you’ll want to avoid doing this, make sure you hit the joint with a sanding disk or file to keep it clean.

Final Thoughts

Now that we’ve covered pretty much everything you’ll need to know about your TIG torch and TIG welder when it comes to welding mild steel, we hope you feel a lot more confident in approaching your welds. We helped you understand how to set up a TIG welder for mild steel, we covered how TIG welding works on mild steel, the TIG power supplies you’ll need, the TIG torch options for welding mild steel, how to set-up your electrode for mild steel, and how you’ll set-up your TIG welding machine for mild steel.

Remember, when it comes to TIG welding with mild steel, practice does make perfect. You’re going to need to retain plenty of your patience while you are learning to TIG weld. Since TIG welding requires you to use two hands, it’s a more laborious process to learn. Also, TIG welding with steel typically requires a little more time, effort, and experimentation to master. So, don’t be disappointed if you’re noticing that learning how to TIG weld is becoming an investment of time.

As long as you are enjoying learning how to TIG weld, and you’re getting there, you don’t have much to worry about as you progress. You’ll get there soon enough. So, get out there and experiment today!

Alexander Berk

A bit about myself: I am a certified international welding engineer (IWE) who worked in different welding projects for TIG, MIG, MAG, and Resistance Spot welding. Most recently as a Process Engineer for Laser and TIG welding processes. To address some of the questions I frequently got asked or was wondering myself during my job, I started this blog. It has become a bit of a pet project, as I want to learn more about the details about welding. I sincerely hope it will help you to improve your welding results as much as it did improve mine.

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