Last Updated on September 19, 2020 by Gary Hargrave
Welding gas or shielding gas is an integral element used in two of the most popular welding processes. They are known as Metal Inert Gas Welding (MIG) and Tungsten Inert Gas Welding (TIG). The core responsibility of welding gas is to protect your weld metal from any unanticipated metal and atmospheric contamination. Besides, it also keeps away oxygen and water vapors from your weld metal by replacing them.
Now, the fact is, there are so many types of welding gases which are basically used in accordance with the type of materials being welded. This means, not all gas types are suitable for welding a certain type of material.
In fact, there might be a combination of two or more gases in order to form a special shielding gas for a particular workpiece. For this reason, it’s very essential to know what are the gas types used in MIG and TIG welding and more importantly, which of them are used for what type of metal.
But first, let’s learn about two of these welding techniques in brief and how welding gas is used with them:
- Metal Inert Gas Welding (MIG): In this case, the electrode is a welding wire that comes from a spool continuously gets fed into the weld pool and use the current to strike up the arc & make a fusion. Now the shielding gas comes along as a cover over the electrode wire and protects the weld metal from having atmospheric contamination.
- Tungsten Inert Gas Welding (TIG): In this process, a non-consumable electrode made of tungsten rod is used with filler metal & shielding gas in order to make a strong joint while protecting the area from metal and atmospheric contamination.
Now it’s time to learn about what types of shielding gas these two welding processes used in order to weld a particular material of their category.
Another interesting article in a similar topic you may enjoy – Why you can’t use the same gas for MIG and TIG welding.
Topics Covered in This Article
Gases Used in MIG Welding: Most Common Ones
There are basically five types of material which are welded using the Metal Inert Gas Welding process. Each of them requires a special blend of shielding gas which may include two or more gases together. Let’s learn about them in particular:
- Stainless Steel: Stainless steel is the most popular item on the list. This material basically uses a blend of three different gases. They are Helium, Argon, and Co2. Now the ratio of these three gases would be 7.5%/ 90%/ 2.5%. This combination ensures the most durable joint and provides a stable arc. Check out this interesting article about MIG welding stainless steel without gas!
- Nickel Alloys: Well this material can use both a blend and non-blend shielding gas in order to protect the process from contamination. Now the non-blend version is to use only pure argon which works quite well with this metal. But in order to get the highest performance in terms of penetration and weld quality, a ratio of 40%/ 60% Helium and Argon should be used.
- Low Alloy And Carbon Steel: These two types of materials basically use a blend of two gases in order to use as their shielding gas. The blend consists of a ratio of 25%/ 75% Co2 and Argon which is perfect for providing high quality and deeply penetrated weld.
- Aluminum: Aluminum is another popular item on the list. Similar to that of nickel alloys, aluminum can use both a blend and non-blend type of shielding gas. But it completely depends upon the thickness of that aluminum. If it’s under half-inch, you should use 100% pure Argon as the shielding gas. Conversely, if it’s more than a half-inch, a combination of a bit Helium and Argon should be used to get the highest quality. But can you MIG weld aluminum without gas? Check this article to know!
- Copper Alloys: Similar to that of aluminum, copper alloys basically uses the combination of Helium and Argon as its shielding gas. The ratio of these two gases is 25%/ 75% of Helium and Argon. Not to mention, this blend can work effectively to aid the highest quality weld.
As you can see among all the gases we have talked about, Argon is by far the most common gas used in all sorts of MIG welding metals. In fact, two of the five types can solely use Argon as their shielding gas. Besides, the other three metals use it as the highest ratio over other gases like Helium and Co2.
Argon is best known for its capability to effectively remove Nitrogen and Oxygen from an environment while making it completely inert. Besides, it’s the most frequently used shielding gas for both MIG and TIG welding. Consequently, we can say Argon is the most common shielding gas for MIG welding.
Gases Used in TIG Welding: Most Common Ones
Unlike MIG welding, there are three common shielding gases which are frequently used in TIG welding. They are Helium, Argon, and Hydrogen. Now consider the type of welding you’re going to perform which will determine whether you’ll need a blend of two gases among these three or only a single form in order to use as the shielding gas. Let’s learn about all of them in brief:
- Pure Argon: Pure Argon is the most frequently used shielding gas in TIG welding. It can be used over all sorts of material welded by this process. You’ll continually get a stable arc with a high-quality finish by using pure Argon.
- Pure Helium: If you are planning to use DC negative power with your TIG welding process, pure Helium can be the best shielding gas for your task. Not to mention, you’ll enjoy a high-quality weld while having deep penetration.
- Helium and Argon: The second most frequently used shielding gas for TIG welding, this blend of Helium and Argon is primary used to provide the adequate amount of heat to the weld metal while protecting it from contamination. Now the ratio of the blend is 50%/ 50% of Helium and Argon.
- Hydrogen: Similar to the blend of Helium and Argon, the pure Hydrogen shielding gas will help provide an increased amount of heat input especially for welding stainless steel in TIG welding.
Another interesting article – Can you use Argon – CO2 mix for TIG welding
Inert and Active Gases: Application Areas
Now we’re going to learn about the definition of inert and active gas including their application areas. So let’s begin:
- Inert Gas: Inert gas is basically known as having the capability to remove oxygen and nitrogen from the environment without providing any sort of reaction and effect. Argon is the most popular type of inert gas.
- Application Areas: Well, all the MIG welding materials except brazing and aluminum use inert gas as their primary source of shielding gas.
- Active Gas: Unlike inert gas, active gas comes with two types of effects. One is when you mix Co2 with Argon as the shielding gas, it considerably increases the voltage of the arc because of being electrically conductive. The second effect is the surface tension gets break down from the weld pool because of the Co2.
- Application Areas: Only TIG welding applications use active gas as their shielding gas because of its ability to effectively burn the non-consumable tungsten electrode.
Shielding gas is one of the most crucial elements while working with MIG and TIG welding. Without a doubt, using the appropriate types of welding gas with a particular metal is more essential since it assures you the highest quality weld by erasing the probability of occurring any sort of contamination.
Thanks for reading the whole post. Stay tuned with us for more welding-related guides and articles.