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)

[table id= 19/]

[table id= 20/]

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.

[table id= 21/]

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.

[table id= 22/]

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

[table id= 23/]

3. Selecting the Gas Type According to Wire Size

[table id= 24/]

MIG Welding Gas Price Comparison

[table id= 25/]

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.

Cast steel is one of the major metals in our day-to-day lives, and there are a large number of objects that are manufactured of cast steel. Therefore, it is typical for a welder to run across a circumstance in his work routine in which he is required to weld cast steel.

I am going to go through the process of welding cast steel in great detail here in this blog. And could you please explain why the cast steel welds that you have been using keep cracking open? now let’s get started.

Can You Weld Cast Steel?

Similar to many other metals, Cast steel can be welded. The only difference is that when you weld cast steel, sometimes the weld will crack.

Because of this, it is very important to choose the right welding method and the right electrode type. We will discuss this in more detail later in this article.

Things You Need to Consider Before Welding Cast Steel

Before attempting your first weld on cast steel, there are a few things to keep in mind.

1. Size of the piece you are welding
2. Controlling the temperature of the weld pool
3. Dealing with the distortion of the piece during welding
4. Service age of the working piece
5. Environmental conditions

1. Smaller Pieces are Easy to Weld

When compared to huge cast steel pieces, smaller ones are significantly simpler to weld. There is less chance of fracture or distortion if you are welding a small piece.

When welding small parts together, you need to pay close attention to ensure those small tiny cracks that may remain even after welding.

2. Controlling the Temperature of Weld-Pool is the Key

When it comes to welding, cast steel is more prone to cracking. Because of this, you need to take extra precautions to prevent the steel from cracking by not allowing the weld pool to cool too rapidly.

This isn’t usually necessary if the casting is made of low-carbon steel or contains manganese, both of which make the material considerably tougher than standard cast steel.

But still, It is an important aspect to consider before starting to weld cast steel.

3. You Need to Learn How to Deal with Distortion During Welding

Cast steel is known for being hard to weld without causing a lot of distortion. cast steels are much more likely to bend than other metals, and this becomes more obvious as the amount of carbon in them goes up.

When welding cast steel, you need to be extra careful that the surrounding temperatures won’t cause problems before, during, or after the process.

4. Service Age of the Workpiece Matters a Lot

The service age of any metal is very important and it directly affects the melting point and strength of the material.

So while working with cast steel you should definitely consider the age of the workpiece that you are welding.

5. Cast Steel Welding Requires Special Environment

The age of the service and the environment in which the cast welding is performed both affect the weld quality.

It’s important to know the temperature range in which your alloy works best since extremes in either direction could make things harder and lead to unexpected results.

Not only that, but Welding is also very hard to do with cast steel because of environmental factors like moisture and humidity.

How to Tell Whether It’s Cast Steel or Cast Iron?

There are 3 ways through with you can identify the difference between cast iron and cast steel.

1. Look at the grain structure
2. Colors of the sparks when grinding
3. Drill and see the chip’s structure

1. Look at the Grain Structure

If the part is broken, looking at the grain structure will help differentiate between cast iron and cast steel. The grain struct of cast iron is a dull and dark type, while the cast steel grain structure is more shiny light grey color.

2. Color of Sparks When Grinding

Grind the part and see what the color of the spark is. In cast iron, the spark color tends to be brightest at the end of the spark stream away from the grinder.

While in cast steel the orange spark develops right at the grinding wheel and then they extend out.

3. Drill Chip’s Structure and Shape

Drill your workpiece and see what the structure of the chip is. In the case of cast iron, the chips are more like refined small particles like lead. while in the case of steel the chips are more like shiny long spiral chips.

How to Weld Cast Steel?

The key to welding cast steel is to keep the metal from expanding and contracting too much while welding and after welding. If you don’t do it, the metal will always break on you.

If you want to succeed, you must preheat the cast steel and let it cool gradually. Depending on the welding procedure you want to employ, you need pre-heat the cast steel to a certain temperature.

In the following paragraphs, I will be discussing in more detail how you can weld cast steel.

1. Preparing Cast Steel for Welding

All metals, including cast steel, need to be cleaned and prepared before they can be welded. If the surface of your cast steel is dirty, you can’t expect good welds to form.

Some of these pollutants could be very bad for your health if they are burned and turn into fumes during welding.

To get the rust off the surface of your steel, you have to work very hard. Rust is a common problem with mild steel, which can make it hard to make a good weld.

The most common problem caused by rust is porosity, which means that there are a lot of small holes in your welds. Porosity can make a weld connection very weak.

There a 2 methods which you can use to clean your cast steel before welding:

1. Mechanical Method
2. Chemical Method

The method you choose will depend on the type of metal, its condition, the way you want to weld it, and the tools you have on hand.

Mechanical Method

When you clean cast steel mechanically, you scrape, brush, or grind the surface to remove dirt. I typically only clean steel parts by hand (without the aid of power tools) when they are really tiny since power tools are a bit too quick. I suggest using a very strong wire brush if you decide to manually clean steel.

Make sure the metal in your wire brush or the metal on the attachment you want to utilize on your power tool is the same metal you’re going to weld when cleaning.

For instance, use a steel wire brush or grinder to clean a piece of steel rather than one made of brass or another metal. If not, there is a chance that the metal will get contaminated with another metal.

Aluminum may be cleaned with a stainless steel wire brush without issue.

Also In many welding facilities, particularly those that weld big pieces, tools driven by electricity or pressured air have become the norm for cleaning steel. Angle grinders are the most used power instruments for cleaning steel.

Chemical Method

As you may have guessed, chemical cleaning is a process that makes use of harsh chemicals to clean steel. Please handle the materials with the greatest care if you want to clean them with chemicals since I’m talking about some very abrasive chemicals here.

Here are a few substances that you may wish to take into account when cleaning steel.

• Acetone
• Alcohol
• Acid

Be aware: Make sure that no spark or flame ever comes into touch with the solvent or its vapors while cleaning steel and other metals before welding. Almost all solvents are very combustible.

2. Selecting the Welding Method for Cast Steel

Any of the modern welding processes may be used to weld steel, although I advise sticking to only:

• Stick Welding
• MIG Welding
• TIG Welding

Here is a brief overview of some important steel welding details for each of those procedures.

Stick Welding

Stick welding is one of the most effective methods for welding cast steel. It’s portable, which is useful when you need to weld a large piece of steel that you can’t readily move, and it’s flexible and economical in comparison to other welding techniques.

You can stick weld nearly any piece of steel with a thickness of 1/8 inch or more.

MIG Welding

It is possible to MIG weld cast steel in any orientation, which is one of the reasons why MIG is the preferred method for cast steel welding projects.

With MIG welding, you may get a very smooth weld, and you can prevent most of the spatter and waste that might occur with stick welding.

As long as you have a strong MIG machine, you can even weld incredibly thin pieces of steel using MIG.

TIG Welding

Similar to MIG welding, TIG may be used to weld cast steel of different thicknesses. TIG also provides a very clear view of the weld area since it generates so little smoke and slag (waste).

If you do not utilize the proper filler rod, the quality of your weld will be severely compromised.

If you pick TIG for your steel welding projects, ensure that your equipment is properly configured. Make sure to use charts that will assist you in determining the appropriate amperage, shielding gas flow rate, and polarity for tig welding steel.

Related Information: MIGvs TIG Welding: Which one is Better?

3. Performing Stick Welding on Cast Steel

For the purpose of demonstration and understanding, I will be assuming that you have selected stick welding to weld cast steel.

Safety Checklist before Stick Welding

• Welding helmet with a filter ranging from #10 to #14.
• Long pants made of leather, wool, or cotton; jacket made of leather.
• Heavy-duty gloves designed for use in welding.
• Eye protection glasses.
• Hat.
• Shoes or boots made of leather.
• Proper Ventilation.

Required Equipment for Cast Steel Stick Welding

1. A grinder for cleaning
2. An oxyacetylene torch to preheat the workpiece
3. Temperature indicating crayon to measure the temperature of the piece
4. Standard Stick welding setup
5. 7018 Stick welding electrodes ( Esab OK 48.15 )

You can use your thermal phone camera to measure temperature when preheating your workpiece.

Choosing the Right Electrode Type is the Key to Success

Probably the most important thing to do when welding cast steel is to choose the right type of electrode. I want you to pay extra attention as you choose the electrode rod for welding cast steel.

Because if you don’t choose the right type of electrode, the quality of the weld won’t be good, and the weld might also crack as soon as the weld pool cools.

Here are a few of the tips that might help you find the right electrode type for cast steel welding:

• Always use the E7018 electrode.
• Make sure to use a low hydrogen content electrode.
• The coating type should be basic.
• It’s better to use an electrode made of “Carbon Manganese” (Not necessary).
• Avoid cast iron rods at all cost

Esab OK 48.15 is one of the many electrodes that fulfill all of the above-mentioned requirements.

The Secret Behind Cast Steel Welding is Preheating the Metal

This is the most important part of this whole article. This step is the one that most welders miss when welding a cast steel workpiece.

Controlling the metal’s expansion and contraction both during and after the welding process is essential for successfully welding cast steel.

The weld will break if you do not do it. If you want to succeed, you must pre-heat the cast steel and let it cool gradually.

When utilizing stick welding, the workpiece must be preheated to a temperature ranging from 150 to 300 degrees Celsius.

To determine the temperature of your cast steel, use a temperature-indicating crayon. Simply mark the metal with the crayon, start the preheating process, and when the metal reaches the temperature specified on the crayon, the mark will melt.

So, if you have a crayon that can mark metal at 300 degrees Fahrenheit, you may mark the metal, heat it with a torch, and then check to see whether the mark melts off to see if the metal has hit 400 degrees.

Selecting the Right Current Type and Amperage Settings

Set the amperage on your stick welding equipment to the appropriate value, and set it to direct current positive (DC+).

For this sort of job, always use the smallest electrode you can get away with in order to keep the welding heat as low as possible.

I advise, when stick welding cast steel wherever possible using 332-inch electrodes.

Lesser heat equals less expansion, which means a lower danger of cracking.

Why I Didn’t Choose MIG Welding for Cast Steel?

Even though it is possible to MIG weld cast steel, I don’t recommend it. Because it requires more skill and it is very difficult to control the temperature of the weld pool which is very crucial in cast steel welding.

Compared to MIG welding, TIG welding is faster and doesn’t have as many problems, like spatter, which can make the finished product look sloppy.

I know Cast steel is hard to weld with a TIG because it needs more precision to avoid warping and cracking. However, if you give it a try, you’ll see why I am preferring TIG over MIG.

Tips for Producing High-Quality Welds When Working with Cast Steel.

Here are few of the important tips that will help you increase your welds quality when working with cast steel:

• To keep your cast steel cold and motionless while welding, use a sandbag or a similar instrument.
• Instead of depending only on clamps, hold components together while you weld.
• Warm up your material to reduce the possibility of fracturing.
• Remember to replace plain steel filler material with stainless steel to avoid deformation and enhance the final quality.
• Avoid allowing your cast steel to get too hot by sheltering it or using water to cool it.
• Remember that bigger pieces of cloth will take longer to heat up and cool down.
• Use stick welding rather than arc welding to reduce the risk of cracking.
• Always refer to the welding manual for the particular cast steel product you are using.
• Use an electrode that is suitable for the level of current you are utilising.

How to Weld Cracked Cast Steel?

Same as above we will be using stick welding process for welding cracked cast steel as well.

Things You Need to Weld the Cracked Cast Steel

• A standard stick welding setup:
• Torch made with oxyacetylene
• electrodes for stick welding manufactured specifically for cast steel
• a drill with a drill bit for cast steel drilling
• A grinder (optional)

Step by Step Process for Welding Carcked Cast Steel

First, you’ll need to prepare the piece by drilling a tiny hole at the end of each crack and maybe even a fraction of an inch beyond it.

Second, using the oxyacetylene torch, bring the cast steel to a temperature of 400 to 1,000 degrees Fahrenheit in the area where you’ll be welding.

Third, switch to direct current electrode positive (DC+) and adjust the amperage on your stick welding equipment to the number recommended for the electrode you want to use.

Fourth, Use an arc that is somewhat longer than the arc used to stick weld steel.

Fifth, begin welding on the crack about a half an inch below the hole you bored in Step 1; return to it and weld a half an inch beyond it while retracing your steps.

Sixth: Return to the hole from Step 5; repeat for any additional holes; weld a bead about 112 inches long in the direction of the centre of the fracture.

Seventh, go back and forth in this manner until the whole crack is filled.

If you want the best results, wait until the first section of the weld has cooled completely before moving on to the second. Cleaning the item after each weld is also recommended.

Spending the extra effort on these procedures is worthwhile if you care about getting a reliable weld.

Wrapping it Up

Controlling the temperature of your weld pool is the sole challenge involved in welding cast steel; the process itself is rather straightforward. If you are unable to maintain temperature control, the weld may fracture, which will lead to a reduction in strength. I really hope that the information that was provided for you will help you find a solution to your issue. I also hope that you enjoyed reading this essay.