Purpose Of Flux In Welding (Functions, Advantages & Disadvantages)

Whether you are just starting with welding or you are already a professional welder, welding flux is something that you will come across at some point. It’s a very crucial part of welding that you can’t avoid at any cost.

Here, I will be diving deep into the purpose of welding flux and how it all works. So, if you are wondering anything about welding flux, then this is the place to be, and you will get all your answers from here.

Let’s get this thing started with –

What Is Welding Flux

The most straightforward answer is that welding flux is a chemical flowing agent inside the tubular wire. It’s a chemical agent that purifies, control flow of oxidation and let the weld clean from slags during welding. While fusing two or more metals through welding, you will need to use some chemicals to ensure the process is done correctly and neatly.

welding flux
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Flux In FCAW

These chemicals are made of different materials and components (Ammonium chloride, Zinc chloride, Hydrochloric acid, Borax etc.)

Simply put, welding flux is a chemical agent that you use in the welding process to get proper welding results.

Why Is It Used

Purpose of flux
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Why do you need to use this chemical agent? What’s the point of using this?

Among many different reasons, the main reason for using weld flux is to avoid any kind of oxidation of the filler materials and the base material in the welding process.

Weld flux is usually composed of such chemicals that can prevent any kind of metal oxide from forming. This almost works like a barrier to the oxygen produced in the welding process and keeps the solder wet with the flux surface.

So, if you want to keep any metal oxidation away from your welding process, then using welding flux is necessary.

What Are The Types Of Welding Flux

There are typically four types of fluxes that you get to see in flux electrodes for welding purposes. Let’s get through them one by one –

Rutile Electrode

This is the kind of flux electrode that uses titanium oxide as the core. With these, you can get pretty good arc control and slag control. It’s a very welder-friendly flux so that you can get used to it as a beginner. It’s the perfect type of flux whenever you need to weld out-of-position stuff.

Iron Oxide Coat

This one is quite the opposite of the rutile electrode, as it won’t be your first choice for welding flux electrodes. This is a mix of several metallic oxides of silica, iron, and manganese. When you put these under heat, they can create a molten acidic slag that you can use in your welding process.

This is not suitable when you are working with metals that can easily go with oxygen inclusion. While using this flux, you will need to add some deoxidizing agents in the welding core to make them work properly.

Basic Flux

Basic flux is made of some essential components that provide excellent results in the welding process. It’s usually made from magnesium carbonate, calcium carbonate, calcium fluoride, and some other compounds that have shielding capabilities.

It’s the perfect choice of flux whenever you deal with steel with very high strength. But as a beginner, you will have a bit of trouble with it, as it’s not that forgiving in the application.

Cellulose Coating

With the Cellulose coated electrodes, you get a mix of some organic compounds and Cellulose. These components give the electrode a characteristic trait of hydrogen and carbon monoxide when heated.

Later on, this creates a weld shielding around the process and results in excellent penetration in the welds. But if you are dealing with metals that tend to have a higher inclusion rate of hydrogen, then you should avoid this weld flux.

To know even further in detail, you will need to dig very deep and learn all there is to learn about the welding fluxes. But these are the four basic types, and you can easily find them out in any welding-related sector.

Composition Of Welding Flux

Typically, you get to see two different parts in a welding rod. One is the actual metal rod, and the other is the flux coating. The metal can be anything like cast iron, mild steel, copper, aluminum, or stainless steel.

Two of the most crucial components for welding flux are iron and Cellulose. These are the base or foundation of welding flux. Along with that, you also get to see some blending of Sodium, Titanium, and sometimes even Potassium.

While the iron is responsible for providing that strong, hard, and metallic base, the Cellulose gives it the characteristic of what we know as the actual welding flux. As for the other blended components, they add their flavor to the welding flux to give it a unique value as well.

Functions Of Welding Flux

Here are the functions of welding flux that make them a necessity in the welding process in some projects.

  • Using welding flux helps prevent the oxidization of metal in the welding process.
  • Welding flux helps in joining the base metals to the filler metals
  • It also impacts a lot in improving any liquid solder’s wetting traits.
  • Great use of welding flux is for cleaning the surfaces of the metals to be welded from any kind of impurities whatsoever.

These are the most common functions that you get from welding flux.

Advantages And Disadvantages

There are plenty of advantages that you may already be aware of when it comes to welding flux. However, there are several disadvantages as well. Let’s take a quick look at both the advantages and disadvantages you get with welding flux –

Advantages Of Welding Flux

  • These provide some high level of weld penetration that you usually don’t get to experience.
  • They are perfect for higher weld productivity.
  • Welding with a welding flux isn’t that difficult to learn at all
  • Very much forgiving in the right kind of setup.
  • Offers excellent welding arc visibility.
  • Keeps away the risk of ignition with the prevention of oxidization.

Disadvantages Of Welding Flux

  • This can produce a lot of toxic fumes, for which you need proper ventilation.
  • The electrode wires with weld flux cost a bit more than regular electrodes
  • These aren’t suited for all kinds of metals, which can be an issue in some cases

What Is The Function Of Flux In Submerged Arc Welding

One of the key parts of submerged arc welding is the use of welding flux. Now, the question is how does it impact the submerged arc welding process, and what is its function there. Let’s find that out quickly. Below are the functions of flux in submerged arc welding –

  • It is necessary for assisting instability and arc striking in the welding.
  • Welding flux helps form a slag to shape the bead of the weld and protect it as well.
  • When molten filler metal projection goes across the arc gap, the welding flux forms up a gas shield and protects the filler metal.
  • This reacts with the weld pool and provides top-quality weld metal with properties that you desire in them.
  • It is immensely effective for deoxidizing the weld pool.

To Which Types Of Welding Do Flux Applied

Whenever people talk about weld flux, they usually think about one type of welding. But in reality, there are three types of welding processes that use weld flux. They are-

  • Stick Welding or Shielded Metal Arc Welding or SMAW
  • Flux-cored Arc Welding or FCAW
  • Submerged Arc Welding or SAW

Typically, stick welding and flux-cored welding are the most common forms of welding that use the welding flux in the process. As for the submerged arc welding, the use of flux is a bit subtle. Also, it’s not that common in terms of a welding process anyways. 


To sum things up, all I can say is the purpose of welding flux is a lot more evident when you have to use it in your welding process. The impact on flux is pretty solid on the welding processes. It’s the core of the welding processes, making welding such metals much easier. Also, it’s quite strong as a welding process as well.

So, if you are getting into welding, then you must know about welding flux. You never know when you might feel the need to jump into this welding technique.

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