Can You Get Slag in TIG Welding?


Slag can be a major annoyance for welders, and many prefer to simply avoid it all together, but could one answer to welder’s struggles against slag be TIG welding?

Can you get slag in TIG welding? You can avoid slag in TIG welding because you do not need to use flux when TIG welding. If you do choose to use flux when TIG welding, you may get slag. 

Flux simply isn’t a requirement for this type of welding, unlike others. If you choose to use flux with your TIG welder, you will run the risk of having slag just as you would with other welding methods. We’ll explore all of this further in the rest of this post.

Using a TIG Welder to Avoid Slag

With stick and wire fed welders, you always run the risk of having slag, which comes from flux. In these types of welding, you have to use flux to protect the weld from contaminants and oxides that would ruin the appearance and stability of the weld.

With TIG welding, you aren’t required to use flux. This is because you’re using a gas shield, instead of flux electrodes. In typical welding, flux electrodes are used to clean the surface of oxides and act as a protection against oxygen to prevent oxidation, which will ruin a weld.

Flux electrodes aren’t required for TIG welding because TIG welding uses gas instead of flux. You can use both together, but the gas protects the weld as well alone as with the flux. The absence of flux prevents any slag from being created in the first place.

How Does the Gas Protect Your Welding with a TIG Welder?

In typical welding, you’d use flux to protect your weld. However, with TIG welding, you use a gas to protect it. We’ll explore what flux is and how it creates slag, but there’s one question directly related to TIG welding and slag we’ll answer first. How does the gas protect your weld?

The flux uses flux electrons to create a shield around your weld against the contaminants present in the air. The gas operates much the same way, turning the contaminants away from the weld and helping to cool it faster. This also leaves a better appearance.

The gas used in TIG welding is commonly argon. Some welders prefer to use a mix of argon and CO2, especially when working with specialty metals, as they feel this works better for the weld. Whatever you use, you want to be consistent with it, as different blends will react slightly differently.

In TIG welding, you can still use flux. However, there really is no reason for it, as we’ll explore in the following sections. One of the biggest pros of TIG welding is the ability to have no slag. However, as soon as you introduce flux, you create the possibility of slag.

Why Don’t We Use Gas in All Welding Pieces?

If the gas operates the same or better than flux electrons, why don’t we use it for every piece of welding? In theory, gas prevents contamination even better than flux does, without the appearance of slag. Why, then, don’t we use the gas for all welding?

The simple answer is, not all welding is TIG welding. The official name of it is gas tungsten arc welding, also known as GTAW. This is because it’s intended to be used for a very select group of metals for a very select group of projects.

TIG welding is slower and much more difficult to master than other forms of welding. The price of tuition to learn how to TIG welding with a certification can be more than most people are able to pay, as well as the cost of paying your employees for longer hours using a slower method.

Unlike MIG, TIG typically uses filler rod, a thin rod of metal that melts into the workpiece to create a solid weld. The filler rod you use depends on the piece, but it typically matches the metal you’re working on unless you’re working with very weak metals, in which a strong filler rod would be used.

What is Flux?

Flux is typically a gel or other thick liquid applied to the area of a weld before you begin the process. The purpose of it is to protect the weld from airborne contaminants, but the downside of flux is slag, which only has to be removed later.

Flux is made of flux electrons. These electrons essentially repel the airborne contaminants from the weld to protect it from being ruined. Using typical welding processes such as stick welding, the lack of flux electrons will allow discoloration and a weaker weld.

This is because of all the contaminants found in the air, especially in an area where welding is frequently done. All kinds of different metal particles are floating in the air, which are attracted to the electricity produced by the torch. They’ll settle into your weld if you don’t use flux.

Contaminants ruin the appearance of your weld. You’ll end up with discoloration and an uneven weld, two things a welder never wants. The unevenness of the weld can also compromise the stability of the weld, allowing it to break or crumble much quicker than it should.

Why is Flux Not Required for Work with TIG Welders?

The gas provides a shield of protection around your workpiece, not unlike flux. In theory, then, couldn’t adding flux to your workpiece only double your protection? If you struggle with keeping contaminants out of your weld, could doubling up on protection be your answer?

For some people, this is their answer. It does offer extra protection to keep your weld free of contaminants. However, when introducing flux to a weld, you are also introducing slag, which is the unfortunate result of flux.

While you can limit slag, and get it to such a fine little bit left that you can simply dust it off with a brush, you will never be able to fully avoid slag completely while using flux. Flux is a substance that’s applied to your weld, and as you can’t completely destroy substances, it will always leave some slag.

On the flip side, many welders who struggle with contaminants getting into their weld will use flux and gas together, and this helps them greatly. As long as you can successfully use flux without creating a large amount of slag, you can get the ultimate contaminant protection using flux and gas on TIG workpieces.

Final Thoughts

In conclusion, yes, you can get slag in TIG welding if you aren’t doing it completely by the book and only using gas. If you’re someone who struggles with contaminants in your TIG weld, using flux as well as the gas can be a great solution.

However, for those who don’t struggle with contaminants and can successfully use just the gas shield to protect their weld, you won’t have to worry about slag. Remember, slag is simply what flux turns into.

Skilled welders are able to minimize the appearance of slag, reducing it to a powder they can brush off or a small scar on the weld that can be chipped off. As we discussed earlier, flux must turn into slag, so when using flux, you will always have some slag.

Flux can only be avoided when you have a gas shield, which won’t work for every style of welding. Work on mastering the gas shield, and you’ll never have to worry about slag on your TIG welds ever again!

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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