Welding is joining two pieces of metal together by melting and cooling them until they become one piece. Welding processes include:

• Oxyacetylene welding
• Shielded metal arc welding (Stick)
• Gas tungsten arc welding (TIG)
• Gas metal arc welding (MIG)
• Flux-cored arc welding
• Torch or oxyfuel brazing

Some methods employ both heat and pressure, while others employ only heat. Welding is commonly used to construct automobiles, airplanes, and buildings. Other metal-cutting methods, such as oxy-acetylene and plasma arc cutting, use heat or electricity to cut through metal.

1. Oxyacetylene welding

Oxyacetylene welding (OAW) is a method of joining two pieces of metal using heat generated by the combustion of oxygen and acetylene gas.

Torch brazing (TB) is similar, but the metal is not completely melted. Instead, a special alloy is melted and used to join the two metal pieces.

Oxyfuel gas cutting (OFC) is a method of cutting metal that uses the same tools and gases as OAW and TB.

To generate heat and bond the metal, all of these methods employ a torch and special gases. They are frequently used on small or thin metal pieces.

Applications:

• Welding and brazing thin or small pieces of metal
• Welding and brazing dissimilar metals
• Cutting and piercing metal

Situations to Avoid:

• Welding thick or heavy sections of metal
• Welding high alloy or stainless steel
• Welding in high wind or outdoor conditions (due to the open flame)
• Welding in confined spaces (due to the production of harmful gases)

2. Shielded metal arc welding (Stick)

Shielded metal arc welding, or SMAW, is a way of welding metal together using an electrode that is coated with a special kind of flux.

The electrode melts and becomes a part of the welded metal. To do SMAW welding, you need a transformer, two welding cables, a work clamp, and an electrode holder.

There are many different types of electrodes you can use for SMAW welding, so you can choose the one that is best for your project. With SMAW welding, you can join different types and thicknesses of metal using the same machine.

Applications:

• Welding thick or heavy sections of metal
• Welding in outdoor conditions
• Welding in dirty or contaminated environments
• Welding on dirty or painted surfaces

Situations to Avoid:

• Welding thin or small pieces of metal (more suited for TIG welding)
• Welding high alloy or stainless steel (can affect the quality of the weld)
• Welding in confined spaces (due to the production of harmful gases)
• Welding in the presence of high winds (due to the electric arc)

3. Gas tungsten arc welding

GTAW, or gas tungsten arc welding, is a method of joining metal using a tungsten electrode. The tungsten electrode generates an electric arc, which melts the metal being welded as well as the end of the filler metal, which is manually applied.

Shielding gas is emitted from the welding gun to protect the molten weld metal from dirt and other contaminants. A foot or thumb switch can be added to the GTAW equipment to help the welder better control the welding.

GTAW welding produces very clean, high-quality welds, but it is slower and requires more skill than other welding methods. It is particularly useful for joining metal alloys that can only be joined with GTAW.

Applications:

• Welding thin or small pieces of metal
• Welding high alloy or stainless steel
• Welding in outdoor conditions (with proper shielding gas)
• Welding materials with high levels of contaminants or impurities
• Welding in high-precision environments

Situations to Avoid:

• Welding thick or heavy sections of metal (more suited for MIG welding)
• Welding in high production environments (slower process)
• Welding in confined spaces (due to the production of harmful gases)
• Welding in the presence of high winds (due to the electric arc)

4. Gas metal arc welding (MIG)

Mig welding is a type of arc welding that uses a continuously supplied wire electrode and gas to weld metal together.

It is becoming more popular because it is easier to learn than other types of welding, like stick and tig welding, and it is faster because you don’t have to stop and change the electrode as often.

Mig welding also creates less slag and spatter, which makes it more enjoyable to use and easier to clean up.

However, MIG welding equipment is more expensive and the MIG gun, which is the portable part of the equipment, can be difficult to use in small spaces. Mig welding also requires a shielding gas to work, so it is not as good for outdoor use.

Applications:

• Welding thick or heavy sections of metal
• Welding high alloy or stainless steel
• Welding in high-production environments
• Welding in outdoor conditions (with proper shielding gas)

Situations to Avoid:

• Welding thin or small pieces of metal (more suited for TIG welding)
• Welding in confined spaces (due to the production of harmful gases)
• Welding in the presence of high winds (due to the electric arc)
• Welding materials with high levels of contaminants or impurities (can affect the quality of the weld)

5. Flux-cored arc welding

Flux-cored arc welding, or FCAW, is a method of joining metal using a special type of electrode wire known as a flux core wire.

The wire is fed from a spool continuously through the welding equipment and out of the gun. The welding current flows through the equipment, melting the wire and the base metal.

Some flux core wires generate their own shielding gas as they melt, while others require the use of additional shielding gas. As the wire melts, it produces a gaseous cloud that shields the weld surface and removes impurities from the molten metal.

After the weld is completed, a layer of slag must be removed from the weld’s top. Despite this additional step, FCAW is a popular welding technique because it produces high-quality welds quickly and is very versatile.

FCAW equipment is similar to that used in gas metal arc welding (GMAW), and both methods are semiautomatic, which means that the wire is fed automatically but the welder moves the gun manually. Welding supply stores and other retailers stock FCAW equipment and filler metals.

Applications:

• Welding thick or heavy sections of metal
• Welding in outdoor conditions (with proper shielding gas)
• Welding in high-production environments
• Welding in dirty or contaminated environments

Situations to Avoid:

• Welding thin or small pieces of metal (more suited for TIG welding)
• Welding high alloy or stainless steel (can affect the quality of the weld)
• Welding in confined spaces (due to the production of harmful gases)
• Welding in the presence of high winds (due to the electric arc)

Comparison Table:

There is a direct correlation between the type of weld that is produced and the shielding gas that was used during the welding process. The manner in which the metal is distributed, the welding speed, the weld contour, the effect that the arc has on cleaning, and the fluidity of the molten weld pool are some of the properties that may be affected. 

So, in this article, we will go over all of the different types of gases that can be used in MIG welding to improve weld quality.

The five most common gases used in MIG welding are Argon, Carbon Dioxide Helium, Oxygen, and Nitrogen. Each gas has its own benefits and problems. But Argon and Its mixes are the most widely used gases for MIG welding.

Choosing the Right Gas Type for Your Job is Not Simple, You Need More Information

As I mentioned earlier, Shielding gas is essential for MIG welding because it prevents the weld puddle from becoming contaminated by the atmosphere. It is critical that the shielding gas moves over the work area at a nice and consistent rate.

The shielding gas supply configuration in a MIG welding operation is relatively simple.  The gas is contained in a pressurized cylinder, and a flow meter is used to reduce the pressure of the gas to a workable level.

The gas is then piped into the MIG welding gun and directed onto the molten pool via a nozzle. But the choice of which shielding gas to use for your MIG welding projects is not an easy one.

When deciding which shielding gas to use, there are several options to consider, as well as several criteria to consider. These criteria include the depth of penetration, porosity prevention, welding speed, and, of course, cost.

In the following paragraphs, I’ll give you some additional information to help you decide which approach to your MIG jobs will be the most successful.

Most Widely Used Gases for MIG Welding

There are five most widely used gas types in MIG welding:

1. Argon (Ar)
2. Carbon Dioxide (CO2)
3. Helium (He)
4. Oxygen (O)
5. Nitrogen (N)

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1. MIG Welding With Argon

The atomic symbol for argon is Ar, and it is categorized as an inert gas. Inert gases are those that do not react with other substances and are also insoluble in molten metal.

While welding nonferrous metals such as aluminum, copper, magnesium, and nickel, as well as their alloys, you can use argon at a concentration of one hundred percent; however, pure Argon is not commonly used when welding ferrous metals.

Due to the fact that argon is heavier than air (unlike helium; we will discuss this in more detail in the following paragraphs), you require less of it when welding because it flows directly onto the weld area from the nozzle. This is one of the most significant advantages of argon.

On the other hand, Argon ionization is not very difficult. Gases that ionize quickly may support longer arcs at lower voltages than other kinds of gases. As a result, it is less susceptible to fluctuations in arc length.

Argon or a combination of argon with other gases is good for the axial spray transfer procedure. Helium and/or oxygen are often combined with argon gas for steel welding.

Argon is an excellent choice if you desire a quiet arc with minimal spatter. You should allocate approximately $100 for a large cylinder of argon or argon mixture.

Pros & Cons of Using Argon Gas in MIG Welding

2. MIG Welding With Carbon Dioxide

One carbon (C) and two oxygen (O2) atoms combine to form carbon dioxide, which has the molecular formula CO2. For MIG welding of steels, carbon dioxide at 100% concentration is commonly used as a shielding gas.

In comparison to inert gases, it allows for faster welding speeds, deeper penetration, superior mechanical properties, and a lower price tag. Carbon dioxide has less steady arc characteristics and significantly more weld spatter, which is the main drawback.

The amount of spatter produced can be minimized by keeping the arc length constant and very short. CO2 can create solid welds if a filler wire with the right deoxidizing additives is used.

In comparison to other gases, its low cost (around $12 for a 244-cubic-foot cylinder) makes it a competitive choice.

Pros & Cons of Using Carbon Dioxide Gas in MIG Welding

3. MIG Welding With Helium

Helium, a nonreactive gas with the atomic symbol He, does not react with molten metals either. Helium can help you make wider welds when welding thick pieces of metal, which is very beneficial in some cases.

The main disadvantage is that because helium is lighter than air, it tends to float away from the weld puddle. And typically necessitates a higher flow rate and significantly more gas than would be required when working with, say, argon.

Because helium is less dense than air, its flow rates must be roughly double those of argon to produce enough gas stream stiffness to displace air from the weld area.

When welding in moist conditions, high flow rates are required to provide adequate protection resulting in high gas consumption.

Higher voltage ionization is required, resulting in a hotter arc. When helium is used, the heat generated by the arc significantly increases. This hotter arc makes welding thick sections of aluminum and magnesium easier.

Helium is added in small amounts to heavier gases. These blends take advantage of helium’s high melting point and the other gas’s superior weld coverage. This means that the blended gas benefits from the properties of both gases.

Helium can consist of up to 80% of a helium/argon mix. If you want more power in your arc without losing the spray mode’s other advantages, mix helium with your argon.

As the amount of helium increases, the transfer becomes increasingly globular, which may require you to change the welding technique. Helium costs approximately $10 more per cylinder (244 cubic feet) than argon.

Pros & Cons of Using Helium Gas in MIG Welding

4. MIG Welding With Oxygen

Although pure oxygen is almost never used in MIG welding but oxygen is very helping in gas mixes. It is really good for stabilizing Arc and minimizing the spatter.

Pros & Cons of Using Oxygen Gas in MIG Welding

5. MIG Welding With Nitrogen

Nitrogen is represented by the atomic symbol N. It’s not an absolutely nonreactive gas, but it won’t cause much trouble in the molten weld pool. It is frequently added to blending gases in order to raise the arc’s temperature. Copper and copper alloys can be welded using pure nitrogen.

Pros & Cons of Using Nitrogen Gas in MIG Welding

Best Mixture Gases for MIG Welding

The welding properties of argon may be altered by combining it with oxygen, carbon dioxide, helium, or nitrogen.

By adding reactive gases (oxidizing) to argon, such as oxygen or carbon dioxide, the arc may be stabilized, metal transfer enhanced, and spatter minimized.

As a result, the penetration pattern is improved, and undercutting is eliminated or reduced.
By introducing inert gases such as helium or nitrogen, the arc heat may be enhanced.

To accomplish the desired results, a very minimal concentration of reactive gases such as oxygen or carbon dioxide is required. A change in oxygen level as minor as 0.5% will have a visible effect on the weld.

Blends containing between 1 and 5 percent oxygen are the most common. Two-thirds of the argon volume can be filled with carbon dioxide.

There may not be enough arc voltage in argon + carbon dioxide +oxygen mixtures with less than 10% carbon dioxide to achieve the desired results. Most applications call for a 25% CO2 argon blend.

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Filler wire containing deoxidizers should be used when welding with oxidizing shielding gases like oxygen or carbon dioxide to prevent porosity in the weld.

Some alloying elements, like chromium, vanadium, aluminum, titanium, manganese, and silicon, can be lost due to the presence of oxygen in the shielding gas.

100% argon’s cathodic cleaning action corrodes steels. The arc might be drawn to the iron oxide in and on the steel’s surface because it is a good emitter of electrons.

However, because of the uneven distribution of these oxides, arc movement and weld deposits are highly irregular. The issue was resolved by mixing in some oxygen with the argon.

A uniform film of iron oxide is formed by the reaction, which provides a stable site for the arc and strengthens the weld pool.

Thanks to this breakthrough, GMAW can now be used to weld ferrous alloys, greatly increasing its versatility.

Steel alloys have different oxygen requirements for arc stabilization. In most cases, 2% is adequate for carbon and low-alloy steels.

About 0.5% should be sufficient to prevent a refractory scale of chromium oxide in stainless steel.

CO2 is a viable oxygen replacement. However, more than 2% is required, with 8% appearing to be optimal for low-alloy steels.

Carbon dioxide is often used as an additive because it improves the weld bead’s contour and gives the arc a more stable appearance.

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Helium is added to heavier gases in trace amounts. These mixtures capitalize on the helium’s high melting point and the other gas’s superior weld coverage.

This means that the blended gas reaps the benefits of both gases.
Sometimes helium makes up as much as 80% of a helium/argon mix.

If you want more power in your arc without losing the spray mode’s other benefits, mixing helium with your argon is the way to go.

As the amount of helium increases, the transfer becomes increasingly globular, necessitating a switch to a different type of welding (to be described later).

Gases like helium and argon do not react chemically with any metals because they are inert.

Selecting the Gas Type Depends on 3 Factors

When selecting a Gas for your MIG welding projects, there are 3 things that you need to consider before choosing the gas:

1. Metal Type
2. Metal Thickness
3. Wire Size

1. Selecting the Gas Type According to Metal Type

2. Selecting the Gas Type According to Metal Thickness

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3. Selecting the Gas Type According to Wire Size

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MIG Welding Gas Price Comparison

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Final Words

It is recommended that you get in touch with the gas provider in your area prior to making the purchase of a tank.

Although the vast majority of businesses do refill tanks belonging to third parties, the processes that they use to do so can vary. However, before you buy a tank, you should confirm that they will fill it for you.