The most common gas used in MIG welding is Argon, but as the name suggests, any Inert or Semi-Inert gas can be used for shielding purposes like Carbon Dioxide and Helium. Even Oxygen, which is a non-inert gas, is used in small quantities for some welding applications.
Which one is best, though, you might be wondering? As they each have their own specific advantages and disadvantages a lot depends on the particular application and type of welding material you are working with.
In the following post, as well as discussing which is best and in what situations we will also look at how much gas you need to use and whether or not you can weld without the use of gas, among other interesting and related subjects.
How to Choose the Right Gas for Your MIG Welding Job?
As we noted above, some welding applications are better suited to a particular type of shielding gas being used. Therefore, you need to give a lot of serious consideration and thought to the goals you have for the welding you are doing. Some important factors you need to take on board include:
- Gas cost
- Properties of the finished weld
- The preparation involved
- Cleaning required following completion
- Base materials you are working with
Let’s take the three most common gases and look at when they might be best used.
If you are interested in getting the optimal results from your weld and that the work looks good, while reducing the amount of cleaning there is required afterward, Argon is an ideal choice. Are you working with non-ferrous metals like titanium, magnesium, or aluminum? You can use 100% Argon. Whereas if you are working with other materials it is recommended you use a mixture of Argon and another shielding gas, preferably CO2.
When you use a 5 to 25% CO2 with 75 to 95% Argon, you will benefit from low spatter and most effective puddle control and arc stability. Especially compared to using either pure CO2 or Argon. With this combination of gases, you also have the advantage of a spray transfer process that allows for welds with more aesthetically pleasing results and greater production rates. Perfect if you have a lot of work to carry out.
As Argon produces a particularly narrow penetration, it’s a sensible choice for butt and fillet welds.
When you are working with non-ferrous metals or stainless steels of various qualities, you should look to Helium as a shielding gas for your welding. One of the biggest benefits that come from using Helium is the fact it creates a deep and wide penetration profile, so it is most effective when working with thicker materials. You can’t use 100$ Helium though.
The most common Argon-Helium mix is 25% to 75% or 75% to 25% ratios. To alter the travel speed, bead profile, and penetration, you simply need to adjust the ratios. A characteristic of Helium is that it produces a much hotter welding arc, that increases productivity rates and causes everything to travel much faster.
It can be problematic if you are trying to keep costs down as Helium is not the cheapest shielding gas to use and as it needs a higher flow rate you need to calculate and compare how valuable increased productivity is against the price increase.
When working with stainless steel, rather than just being used in combination with Argon, CO2 is also included.
Although it is not an inert gas and actually a reactive gas, Oxygen is most commonly used in mixtures that include 9% or less in it. This is especially the case when working with stainless steel, low alloy, and mild carbon as it helps improve arc stability, penetration, and weld pool fluidity.
However, as you’d expect, Oxygen causes oxidation of the metal you are welding, it is best avoided if you are working with metals like copper, magnesium, and aluminum.
Frequently Asked Questions:
How Much Gas Do You Need to Use When MIG Welding?
Now that we’ve discussed the different gas combinations you should be used for different materials; you may be wondering how much gas you should be using. Although it will depend on the type of material you are working on and how thick it is, on average you should be looking at between 25 and 30 CFH (cubic foot-pounds per hour).
Just remember that the thicker the metal, the more gas you need to not just complete the weld, but make it look good too.
Can You MIG Weld Without Gas?
We have spent some time discussing the different gases that are suitable for MIG welding, and we’ve done that because primarily MIG welding is done using gas. However, is there any form of MIG welding that does not require the use of gas?
The great news is that yes, you can MIG Weld without using gas. You will come across two different names when you venture into gasless MIG welding. That is, some sites and welders will refer to a no gas MIG welder and a Flux Core Wire Welder.
Before you start getting worried about any confusion the addition of flux core wire welder brings, all you need to know, especially as a beginner is that a no gas MIG welder and Flux Core Wire Welder are the exact same thing.
How Does No Gas Welding Work?
Instead of using a gas to protect the weld metal, a Flux Core Wire Welder or No Gas Welder uses a hollow wire packed with lots of flux. Hence the alternative name. The flux protects the molten weld puddle as it cools down, in a similar way to a shielding gas in normal MIG welding.
Why Might You Choose to Use a No Gas MIG Welder?
There are several great reasons why you might choose a MIG welder that does not require gas to complete tasks, such as:
- You are a beginner and want to get the hang of using a MIG welder without the additional expense and complexity of using a gas cylinder.
- You have some quick work you need to complete. No gas MIG welding is faster to prep, less expensive, and requires less clean-up too.
- You are working outside. As this is such a big advantage, we’ve highlighted this separately below.
Advantages of No Gas Welding Outside
Granted, a lot of the MIG welding you will be doing will be done inside in a workshop or similar setting. However, what if on those rare occasions, you are working outside and don’t want to use a traditional MIG welder. This is when having a no gas MIG welder is particularly useful. Trying to use gas to protect the molten weld is not easy when there is a blustery wind blowing. It gets blown away and you are left with the less than attractive holes in your work, referred to as porosity.
When you use a flux core wire welder, however, you don’t have the problem of the flux being blown away as it is on the inside and creates the slag onto the top of the metal weld bead as it starts to cool. This protects the puddle from the wind while also performing its main job of preventing atmospheric gases from reacting and deteriorating the puddle.
Can You MIG Weld Stainless Steel Without Using Gas?
This question comes up a lot online and we thought this was the perfect point in our guide to addressing it. Yes, technically, it is possible to use a simple stick welder if you plan on welding your stainless steel to something like mild steel. You can use a common alloy like 308 without using gas.
You need to obviously use flux. The only downside is that the finished weld is unlikely to look very good aesthetically.
Wrapping It All Up
So, what have we discussed? That the best gas to use when MIG welding will be different depending on many different criteria, including the type of material you are using, your production budget, and how pretty and professional you want it to look. We have also looked at the possibility of not using any gas at all, but if you are working with a metal like stainless steel, we can almost completely guarantee that the results will not be pleasant.
For more information on welding, check out some of our other helpful posts and guides, or drop us a line and we will get back to you.