Last updated on May 30th, 2022
Mig welding is a simple and basic procedure that offers a better chance to finish the weld properly. Instead of other welding methods, it doesn’t include many complexities. With Mig welding, users use a gun that’s connected to a spool-fed wire system and a gas hose that supplies the gas and protects the weld puddle from environmental gases.
Contamination can quickly disturb the weld quality, so the gases are significant to retain the weld quality. Weld strength, creativity, and arc actions are fully dependent on a shielding gas that you use. Although, the mixture of 75% argon and 25% Co2 is common gas for metal inert gas welding, but there are many other also exists.
So, which is the best gas for mig welding? It varies from metal to metal and we’ve covered all this in this blog. After going through all this, you’ll be able to choose the best gas for your welding tasks.
Gases Used in MIG Welding
In this welding process, several gases are employed, some of which are reactive while others are inert. All of these are distinct from one another, and the intriguing aspect is that when they are merged, you will discover something new and unique. You may also perform mig welding without gas with proper settings. Below are some types:
Helium ( He )
Helium is a pure gas like argon and is a bit expensive. Because of the strong ionization potential, it’s added to argon and Co2 to weld stainless steel and non-ferrous metals. After the weld, helium goes away from the weld pool due to its low weight and you have to increase the gas flow rate.
Hot arc is the reason for its travel speed and weld penetration that’s beneficial for thick magnesium and aluminum. Mixing helium with argon can change these attributes, but make it affordable.
- For ferrous metal
- Added with others to weld stainless steel
- Deep penetration
Oxygen ( O2 )
The reactive gas is around 9% of the shielding gas mixture. One can’t use only oxygen because it causes corrosion, so it should be mixed with argon and Co2 to enhance weld quality. As it causes corrosion, so don’t use it for magnesium, copper, and aluminum. You may think, then what’s its benefit?
It increases the weld pool fluidity, penetration, and arc stability when used with low carbon, stainless steel, and mild steel. Moreover, steel welding with pure argon unstabilizes the arc, and iron oxide affects the arc with 100% argon, so adding a little amount of oxygen to it will stable the arc.
- Improve pool fluidity
- Excellent penetration
- Stabilizes the arc when mixed with argon
- Can’t use pure oxygen
Argon ( Ar )
The most common gas and it’s used with 5% to 25% carbon dioxide to increase the quality of the weld. It’s heavier than air and protects the molten weld pool from surrounding gases. Because of its easy and quick ionization, it can withstand long arcs at low voltage levels.
With pure argon, you can weld non-ferrous metals such as aluminum, nickel, copper, magnesium, and titanium. On the other side, it creates thinner penetration that’s useful when welding on edges. Usually, it’s used with a mixture of oxygen or carbon dioxide.
- Weld non-ferrous materials
- Increase weld quality
- Easy ionization
- Narrow penetration
- Pure argon is not suitable for steel
Carbon Dioxide ( Co2 )
An interesting fact is that it can be used in pure form without adding any inert gas. Most welders prefer these because it’s the only low-price shielding gas. As pure Co2 provides deep penetration, so it’s better to use it on thick metals.
Further, you can’t weld thin materials with it. On the other side, less arc stability and more spatter are common issues with it.
- Deep penetration
- Can be used in pure shape
- More spatter
- Not for non-ferrous metals
Mixture of these Gases & Benefits
Below is the different blend of these gases and what we experienced from it is given below:
Argon and Carbon Dioxide
It’s the common mixture and with this blend, you’ll get low spatter, better control over weld puddle, stable arc, and penetration for welding stainless steel and carbon. The standard ratio is 75:25, but you may increase it to 85:15 to get a sharper bead finish. It’s the best mixture for less spatter and a better finish. It’s the best gas for mig welding stainless steel and mild steel.
Argon, Helium, and Co2
The mixture of these three gases results perfect for stainless steel mig welding.
Argon and Oxygen
As explained earlier, oxygen stabilizes the arc when mixed with argon for stainless steel welding. Even, 2-3 percent amount of oxygen makes the process smooth for low alloy steel and carbon welding.
Oxygen, Carbon Dioxide, and Argon
This mix, like the previous one, can successfully weld stainless steel and low alloy steel in all-metal transfer modes.
Argon and Helium
It’s the best mixture of these two gases to weld non-ferrous metals and thick pieces such as aluminum, magnesium, and copper. The concept is simple, helium produces a hot arc that quickly welds the thicker metals. Speed is the main part of this mixture. In short, it’s the best gas for mig welding aluminum.
Helium and Co2
This bond is ideal for non-ferrous and thick metals due to its large and deep welds. Before using any mixture, you must be aware of accurate gas pressure for mig welding.
How to select the best shielding gas for mig welding?
All of the fundamental concepts have been discussed, and now you must determine which gas is best for you. The gas is an important part and prevents your welds from certain issues. These are some factors that can help to select any gas.
If you’re tight on budget, carbon dioxide is the perfect choice for its low cost. Secondly, instead of other gases, you can use it in its pure form.
Those who’re conscious about cleaning, use the standard mixture of argon and Co2 with 75:25 ratio to get a clean weld with stable arc and less spatter.
Material thickness is another important consideration. You can quickly select any specific gas or mixture if you’re known about the material thickness and it could be more economical.
Blend of Three Gases
The mixture of helium, argon, and Co2 is ideal for stainless steel due to its fast speed, penetration, stable arc, and excellent bead. Remember, don’t always rely on it, tri-mix varies according to metals.
MIG welding is mostly used for stainless steel and most hobbyists and fabricators always get confused while selecting the shielding gas for it.
Always use pure argon gas or a mixture of argon and helium when welding aluminum. You will harm your weld if you use any reactive gas for aluminum. If the metal is thicker than 1/4 inches, a He/Ar mixture is preferable; else, use simply argon.
Frequently Asked Questions
The noble gases helium and argon are the most widespread. They produce less spatter due to their strong chemical resistance. The arc and shielding weld are protected by noble or inert gases.
Argon and carbon dioxide mixture is the best one to achieve better results and finish. Moreover, it’s perfect for welding mild steel and the first choice of hobbyists and beginners.
All of the main points have been explained precisely, however, one must check the mixtures before starting welding. From the given information, you can quickly select the best gas for mig welding. It’s preferable to buy a gas tank or cylinders from your local supplier.
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