What Gas Is Used For MIG Welding? Fundamentals Of MIG

Do you want comprehensive knowledge about What Gas Is Used For MIG Welding? MIG (GMAW) welding produces a clean, slag-free weld using shielding gas and a solid wire electrode. Unlike Stick welding, this does not need to stop welding to change the electrode.

Just two advantages of this approach are greater production and less cleanup. Understanding the function of shielding gas, the many shielding gases available, and their distinctive qualities aids in achieving these outcomes in your particular application.

Shielding gas is primarily used to keep the molten weld pool from coming into contact with atmospheric oxygen, nitrogen, and hydrogen. The interaction of these components with the weld pool can lead to several issues, including porosity (holes in the weld bead), excessive spatter, and other issues.

Employing various shielding gases affects various factors, including the transfer procedure you utilize, the mechanical characteristics of the completed weld, the arc stability, and the weld penetration profiles. Making successful MIG welds also requires choosing consumables for MIG guns that produce shielding gas consistently and smoothly.

What Gas Is Used For MIG Welding?

100% argon is the most typical gas used for MIG welding aluminum. Due to its low ionization value, this gas makes it simple to switch into a spray transfer or pulse spray transfer mode for aluminum. Another advantage is the ability to use 100% argon gas for TIG welding metal.

Gas Is Used For MIG Welding

What Does Shielding Gas For MIG Welding Serve?

The base and filler metals are fused during welding to form a molten puddle. The shielding gas shields puddle from nitrogen and hydrogen-containing pollutants in the atmosphere.

Without shielding gas, the final weld would have porosity, a flaw that causes it to be extremely brittle and studded with tiny holes once it solidifies. The shielding gas covers the molten weld puddle like a blanket, sealing it from the outside environment.

What Does Shielding Gas For MIG Welding Serve

The parameters of the weld are also influenced by the type of gas used. Along with many other aspects, the gas you choose can affect the amount of spatter, the arc’s stability, and the arc’s performance.

Additionally, the kind of shielding gas you’re employing affects the welding transfer you wish to achieve. Therefore, to do a spray transfer, globular transfer, or short-circuit transfer in MIG welding, you must choose a specific type of shielding gas for each transfer mode.

For instance, it is challenging to perform short-circuit transfer mode but simpler to achieve spray transfer in a shielding gas with a high argon content.

MIG Welding Shielding Gases Commonly Used

To match the base material they are welding, hobbyist welders typically employ three types of filler metals: solid steel wire for mild steel, aluminum wire for aluminum, and stainless steel wire for stainless. Depending on the material being welded, there are different shielding gas alternatives.

Welding Gas For Mild Steel

A mixture of 75% argon and 25% carbon dioxide (also called “C25 gas”) is frequently used for welding mild steel. It offers good arc qualities and less splatter. It also has an excellent bead profile, enabling it to wash off well at the weld’s toes. This combination has a cost disadvantage compared to other combinations.

100% carbon dioxide, often known as C100, is another gas used for mild steel. It’s a good substitute that costs less than a 75%/25% shielding gas combination, albeit it might result in a little bit more splatter and a little irregular arc.

However, as technology in welding power sources geared at do-it-yourselfers advances, the equipment performs better with 100% CO2 gas than it did ten or fifteen years ago.

Although it’s less frequent for the DIY user, a 90% argon/10% CO2 gas, or C10 gas, is an excellent alternative for that if you’re going to utilize MIG welding and enter a spray transfer mode (for example, when welding a thicker plate).

Gas For Silicon Bronze Welding

DIY welders increasingly use silicon bronze filler metal to weld various coated materials or other metals for projects like auto maintenance and artistic and sculptural welding. An ERCuSI-A silicon bronze filler metal produces a procedure similar to MIG brazing.

Usually, you want to utilize a shielding gas that is 100% argon. Using silicon bronze filler metal enables a beautiful short-circuit transfer that aids in the puddle washing out.

Choosing The Correct Gas For Shielding

Numerous MIG welding applications are compatible with a range of shielding gas options. You must examine your welding objectives and applications to pick the finest one for your specific application. When choosing, keep the following in mind:

Porosity, which is visible on the weld bead’s face and interior, can be brought on by insufficient shielding gas and significantly weaken the weld. 

  • The price of petrol
  • The qualities of the welded joint
  • preparation and cleanup following a weld
  • the basic substance
  • The welding procedure
  • your aims for productivity.
Choosing The Correct Gas For Shielding

Argon, Carbon Dioxide, Helium, and Oxygen are the shielding gases most frequently employed in MIG welding. Each has particular advantages and disadvantages depending on the application.

Carbon Dioxide (CO2)

Carbon dioxide (CO2) is the most widely utilized reactive gas in MIG welding. This is the only one which can be utilized without adding an inert gas in its pure state. Because CO2 is the least cheap common shielding gas, it is a desirable option for minimizing material costs.

The deep weld penetration offered by pure CO2 helps weld thick material. But it also generates more splatter and a less stable arc than when combined with other gases. Additionally, it is restricted to the short circuit procedure alone.


For businesses prioritizing weld quality and appearance and minimizing post-weld clean-up, a mixture of 75–95% argon and 5–25% co2 can be ideal. Compared to pure CO2, it will offer a preferable fusion of arc stability, puddle management, and decreased spatter.

This mixture also permits the employment of a spray transfer method, which can result in welds with higher productivity rates and better aesthetics. Additionally, the thinner penetration profile produced by argon is advantageous for fillet and butt welds. It would help to use 100% argon when welding non-ferrous metals like aluminum, magnesium, or titanium.


In low alloy, mild carbon, and stainless steel, oxygen, another reactive gas, is often employed in nine percent or fewer ratios to enhance weld pool fluidity, penetration, and arc stability. However, it is not advised for use with aluminum, magnesium, copper, or other rare metals because it results in oxidation of the weld metal.

Like pure argon, helium is typically used with non-ferrous metals but can also be used with stainless steel. Helium performs well with thick materials because it generates a wide, deep penetration profile; it is typically employed in ratios of 25–75% Helium to 75–25% Argon. The penetration, bead profile, and travel speed can all be altered by adjusting these ratios.

Faster travel times and higher production levels are made possible by helium’s “hotter” arc. But compared to Argon, it is more expensive and demands a larger flow rate. It would help if you weighed the worth of the higher productivity against the rising gas prices. Helium is frequently utilized with stainless steels in a tri-mix combination with Argon and CO2.

Shielding Gas Best Practices

Although selecting the appropriate shielding gas is crucial, use these best practices for better outcomes.

Verify The Flow Rate And Proper Setting

Close the valve on top of the canister after allowing a tiny amount of gas to escape before connecting the shielding gas. This cleans the connection so that no impurities, such as dust, can enter the welding system when you attach the regulator.

Then, attach the regulator by the owner’s manual’s instructions. A regulator often has two dials. The left will regulate the gas flow rate, while the right will regulate the gas cylinder.

The right flow rate is determined by the welding technique utilized. Utilizing a gas flow rate of 25 to 35 cubic feet per hour (cfh) is advised while MIG short-circuit welding. While MIG processes using different transfer modes (other than short-circuit transfer) can run slightly more than 35 cfh, TIG welding normally operates at a lower flow rate.

Because there isn’t enough coverage to shield the puddle, a flow rate that is too low will cause porosity to be introduced into the weld. An excessively high flow rate consumes gas and may also result in turbulence, an Eddy current, and ambient pollutants that induce porosity in the weld.

When using a gas-shielded welding process outside, erect a wind block or tent to keep the wind from carrying the gas away.

Clean The Consumables

The contact tip, diffuser, and nozzle are consumables for your MIG gun. The weld puddle is covered by shielding gas thanks to the nozzle. While welding, spatter, and other particles could clog the nozzle.

Spatter buildup can interfere with the shielding gas coverage if it becomes too great. Make sure to remove the nozzle periodically and remove any extra buildup using pliers or another tool.

Adjust The Contact-Tip-To-Work Distance

If you’re having problems with shielding gas, consider adjusting your CTWD.

Shielding gas may be lost if welding is too far from the work surface and not reaching the weld puddle. Try bringing the gun’s end closer to the sub-material. Although it depends on several variables, a typical recommended CTWD is 1/4 inch to 5/8 inch.

Verify Each Connection

The first step in troubleshooting gas coverage problems is to double-check all connections on the rear of your power source. There are often two distinct gas ports on Multiprocess welding power sources, one for TIG and one for MIG. Ensure the port you are using is the correct one. Next, make sure your cfh is configured correctly.

After completing these steps, ensure the MIG gun is properly placed in the drive system if you still aren’t receiving shielding gas. Insufficient seating causes the gas to exit at the system that drives rather than the MIG gun’s tip. On the MIG gun, think about employing an external flow meter. This will track the cf rate you’re receiving from the gun.


So, What Gas Is Used For MIG Welding? You must carefully consider the kind of welding you’re doing in addition to your operational priorities to select the best shielding gas for your particular application.

The learning process should get off to a solid start if the tips above are followed. Before making a final choice, speak with your neighborhood dealer about welding supplies.

Frequently Asked Questions

Which gas is ideal for MIG welding?

Two main gases are utilized for MIG welding: pure argon and an argon/carbon dioxide mixture. The most popular (and advised) Ar/CO2 mixture is a 75/25 ratio, with 75% argon and 25% carbon dioxide.

Do MIG welders use CO2 or argon?

The primary shielding gas used for tig welding, mig welding aluminum, and mig brazing is argon. Pure Co2 is still used, although a combination of Argon and Co2 is the most used Active Mig Welding Gas.

Can I weld using MIG and CO2?

Regarding MIG welding, carbon dioxide (CO2) is by far the most popular reactive gas. Only this one may be used effectively in its natural state without adding inert gas. To cut expenses, you could use carbon dioxide as your shielding gas of choice.

Welding with argon CO2: Why is it used?

Argon-CO2 mixtures are necessary for MIG welding to get more heat and penetration. In the MIG process, the gas screens the wire, the arc, and the molten metal from the environment.

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