MIG welding gas

MIG welding gas can either be reactive or non-reactive. Several factors, like the material, application, transfer method, and overall cost, must be considered before you decide on the gas you’ll use. 

Anyone remotely associated with the basics of MIG and TIG welding knows how important gasses are for both processes. Using the correct MIG welding gas can have a massive effect on the quality of your welds and save both your time and money.

Are you a home welder who often feels overwhelmed by the number of different MIG welding gasses available in the market?

If yes, then read on. In the following text, you’ll learn everything you need to know about choosing the best MIG welding gas for your project.

Welding Gasses: Why are they important?

In any arc welding process, the weld quality becomes susceptible to changes and weaknesses due to the excessive heat and environmental contaminants. Air consists of multiple oxidizing agents like Nitrogen, Oxygen, and Hydrogen. These gasses can easily react with the heated metal in the molten pool and weaken the mechanical properties of weld with porosity and other material defects

While there are many processes that welders use, this article will only focus on the most common one, gas metal arc welding and the best mig welding shielding gas.

Just as its name suggests, shielding gasses act as a barrier between the contaminating environmental gasses and the welded joint. These gasses are mostly inert, so they don’t react with the welded part itself and keep the structural integrity of the welded part intact.

Shielding is a necessary process for MIG welding and can’t be left out unless you are using a flux coated filler. The flux coating works similar to the shielding gas and prevents the hot metal joint from going through a chemical reaction, which is likely to happen due to the involvement of heat.

The gas you use for shielding also affects the quality and features of your metal transfer rate and the amount of spatter. Shielding gasses can contribute to the stability, weld pool penetration, and strength of your weld. In some cases, only a particular gas can be a suitable choice if you want to get a proper weld.

Mig Welding Gas Prices Around The US

To give you an idea of the rage in prices from around the different cities in America I called some welding gas suppliers. Some states only allow 80 cu/ft cylinder as the largest own your own gas cylinders, but you can rent up to 300cu/ft. I found the rentals can be from $6.49-$12.10 per month.

City Cylinder Cost 125 75/25 125 Argon
Portland
$219
$52.50
$49.50
Arizona
$220
$50
$50
Houston
$246
$32.72
$31.63
Montana
$288.75
$79
$143
Boston
$250
$40 80 CF
$52 80 CF
Baltimore
$255.90
$50.80 80 CF
Alabama
$225
$25 80 CF

The Most Common Gasses For MIG Welding

Multiple gasses are suitable for MIG (metal inert gas) welding. For the sake of this article, the focus will be only on gasses that are available in the market and can get the job done for the home hobbyist welder.

The below gases can be used in any welding position. The welding equipment will all be the same, the regulators for carbon dioxide are different from Aaron or argon blends.

Industrial Grade Carbon Dioxide CO2

If you are looking for an economical option and can compromise on the aesthetic aspect of the results, then this is the best bet for you.

CO2 is one of the most common gasses on the planet with a limitless supply, so you can easily find it anywhere. It has harsher characteristics for welding jobs and has greater penetration power. This quality makes CO2 a suitable choice for welding thicker pieces with ease.

You can use carbon dioxide in its pure form or mix it with another inert gas. Argon and CO2 mixtures are quite popular in the market. I prefer CO2 on thin material like in autobody work due to its wide penetration profile. The finished weld in this work is ground flush to restore the factory look of the panel. CO2 is well suited to short circuit transfer.

It can even give a small 110-volt welding machine the ability to weld thicker work piece as if its a higher voltage machine.

Dealing With Regulator Freezing

Though it can happen with any gas, regulator freezing at a higher flow rate is a common issue with high flow rates of CO2 for long periods. Gasses in cylinders are at high pressures. Whenever released, these gasses suddenly shift from a high-pressure region to a low-pressure one. The sudden expansion causes evaporation.

Remember high school physics? Evaporation causes a cooling effect, and in the case of constant CO2 discharge, the temperatures can go below the freezing point.

Most regulator manufacturers use different techniques to minimize the effect of freezing. Some experienced welders recommend using heated regulators to eliminate this issue when dealing with jobs needing high flow rates for a long time.

C25: 75/25 Argon – CO2 mixture

There are multiple mixtures available in the market that can act as a MIG welding gas. However, none of them can match the popularity of the Argon/CO2 mixtures that are known for their smooth weld, minimum spatter, and appropriate penetrating power resulting in an attractive weld bead.

The composition of Argon in the mixture can be anywhere between 95% to 70%, while CO2 makes up the remainder. The composition of the mixture determines the penetration and other characteristics of the weld. Generally, you’ll need to increase the percentage of CO2 for joining thicker metal pieces.

In most welding applications, the mixture known as C25 (75% Argon and 25% CO2) is commonly used. Most home welders prefer this mixture because of its optimum balance between the arc stability and penetration.

The shielding gas is a popular choice for carbon steel welding applications. Fabricators making items made from thicker material need increased productivity from quicker welding time thanks to the carbon-dioxide allowing for excellent weld penetration and puddle fluidity. The argon allows for the high quality welds by mitigating the excessive spatter of the weld area base material. Clean-up time is expensive so the argon plays an important role.

Argon

Argon, another abundant gas, is quite popular in the welding community due to its inertness and capabilities. This element belongs to the group of noble gasses that do not react with anything. This quality makes Argon a great shielding gas for both TIG and MIG welding processes.

Argon is a staple choice for many welding professionals due to its smooth weld and stable arc in TIG welding. However, using pure Argon as a MIG welding gas can cause some issues for you if you are working on ferrous metals.

Pure Argon does not have enough thermal conductivity to maintain a fluid weld pool in MIG welding. The lower conductivity allows the outer edges of the joint to cool down prematurely and create a weak and brittle joint of subpar quality. However, the same qualities that make pure Argon a suitable MIG welding gas for some particular materials like Stainless Steel, Aluminum, Tungsten, and other non – ferrous metals. (More on that later)

Best Gas for MIG Welding

Working with Steel: The Best Choices For MIG Welding Mild And Stainless Steel

Multiple advances in making Steel production cheaper and efficient have made this metal a regular part of our lives. There are countless types of Steel grades available in the market, and each type is suitable for a variety of applications. From construction to the aerospace industry, and automobile to the manufacturing industry. None can reach their full potential without the use of Steel.

Given how common Steel is, it is natural for any welder, whether apprentice or professional, to know how to work with Steel. The shielding gas you use for MIG welding plays an important part in determining the quality of your weld. Therefore, you should know about the best choices for at least the most commonly used Steel types, i.e. Mild and Stainless Steel.

For carbon Steel or any other carbon Steel, the best MIG welding gas would be the mixture of 75% Argon and 25% CO2. It provides enough arc stability and penetration to deliver strong and aesthetic results. You can use pure CO2 as well, but it will not give the required results.

For Stainless Steel, the best MIG welding gas depends on whether the Steel you are using is austenitic or ferritic. A mixture containing Argon as the major gas is still your best bet for Stainless Steel. However, the best blend for this application will have more gasses like Helium and Hydrogen. Some of the popular mixtures that show great results for MIG welding Stainless Steels are:

  • A mixture of 98% Argon and 2% Oxygen: Best for welding thing joints quickly. May produce some spatter.

  • A mixture of 97.5% Argon and 2.5% Carbon dioxide: Great choice for thin joints needing a smooth welded surface.

  • A mixture of 62% Argon, 35% Helium, and 3% Carbon dioxide: An extremely versatile blend for thicker joints needing more penetration and greater speed.

  • A mixture of 96% Argon, 3% Carbon dioxide, and 1% Hydrogen: A great choice for applications needing an aesthetic finish on thinner joints.

  • A mixture of 64% Argon, 35% Helium, and 1% Oxygen: Similar results to number 3. Works for over a range of thicknesses and produces a stable arc which allows greater penetration without spatter

MIG Welding Gas Choices For Aluminum

Welding Aluminum, or any other non – ferrous metal, is not a simple task. Multiple factors may affect your results. You can follow this incredible step by step Aluminum welding guide to learn the process.

When it comes to selecting the best MIG welding gas for Aluminum, the first thing you’ll need to remember is that Aluminum will only work with inert gasses, so mixtures containing reactive gasses like CO2, Oxygen, and Hydrogen are out of the question.

Pure Argon is still the best gas for any home welder looking to work on some exciting Aluminum projects. It doesn’t matter whether you are using the MIG or TIG process. This gas is perfect for both when it comes to dealing with Aluminum and other non – ferrous materials.

The close second to pure Argon for MIG welding Aluminum is Helium. For thicker welds needing greater penetration, mixtures with higher Helium percentages are more common.

Some of the commonly used mixtures for welding Aluminum are listed below:

  • A mixture of 90% Argon and 10% Helium: Great for smooth results on thin Aluminum pieces.
  • A mixture of 73% Argon and 27% Helium: Known for its quick speed and minimal spatter. Can’t work in thicker weld joints.
  • A mixture of 50% Argon and 50% Helium: A versatile blend with a decent finish. It can work for a wide range. 
  • A mixture of 25% Argon and 75% Helium: The best choice for a quick and penetrating weld joint. This mixture is also easy to use. 

The Best Cylinder Tank Size For MIG Welding

No one likes to take unnecessary breaks frequently to refill their welding gas during their project!

No matter what type of gas you are using for your welding application, they are always stored in high-pressure cylinders and large gas bottles. The requirement of the best tank size varies depending on the application, frequency, the processes, and several other factors.

Technically, the size of your cylinder doesn’t matter when it comes to the processes you can perform. You can even use the smallest cylinder for purging, which consumes a lot of welding gasses quickly. However, the total operational time available to you will be very low.

Are you interested in learning more about cylinder sizes for both MIG and TIG welding processes? Check out this guide to selecting the best welding gas cylinder size according to your needs. 

Are you interested in learning more about cylinder sizes for both MIG and TIG welding processes?

MIG Welding Shielding Gas Key Take-Aways

For the home hobbyist welder or serious DIY welding the best balance to penetration and spatter control in C25. Plus it is very easy to get from the smaller welding supply stores

For any welding application, there are a lot of gasses available in the market today. However, you don’t need every single option available in the market. There is no such thing as the best MIG welding gas as every option comes with its own set of pros and cons.

Some specialized welding applications will have some tough criteria, so you’ll need to procure a specific mixture/gas for it. However, in most cases, you’ll find that common choices like C25, Argon, CO2 can work perfectly and deliver acceptable results.

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