Mig Welding Gas | Types, Guide, TIG and Charts

MIG and TIG Welding is a common process that is used to join two metals together to build or repair cars, boats, buildings and just about any other structure consisting of metal, but you need to make sure to use the correct MIG welding gas to get the best results.

Before you begin a welding project however it is important that you think about what method of welding you will be using.

There are a couple of main types of welders that you will commonly use for most projects, these are:

  • MIG (Metal Inert Gas) Welder, sometimes referred to as a GMAW (Gas Metal Arc Welder)
  • TIG (Tungsten Inert Gas) Welder,  sometimes referred to as a GTAW (Gas Tungsten Arc welder)
  • SMAW - Stick welder or Shielded metal arc welder
  • FCAW - Flux Cored arc welder

When considering a welding project you need to know what types of metals you are wanting to join and what type of welding gas you will need to use.

If you are less experienced or are only looking to make quick repairs that don’t need to be particularly strong, you might opt for a gasless method.

Do you have to use gas with a MIG welder?

MIG welders are convenient and easy to use.

A no-gas MIG welder, as the name implies works without the need for gas. In place of using gas the no-gas welder (also known as a flux welder) uses a hollow wire filled with flux.

With a traditional MIG welder, gas is used to protect or shield the newly created weld as it cools, flux works in much the same way.

It is important to use a high quality regulator to control the pressure of the gas, especially if you are using a home welding device.

Check out our Welding Helmet Review

As the flux is heated it releases its own gas to protect the weld pool.

Both have their advantages.

MIG welders are suitable for joining:

  • Nickel
  • Copper
  • Aluminium
  • Magnesium
  • Stainless steel
  • Other alloys

MIG welding gas pressure chart

Metal

Gas Flow CU. FT./HR.

(CFH)

Type of Metal

Thickness

Argon

Helium

CO2

Steel

.035 - 3/32

8 - 10

20 - 30

8 - 10

Cast Iron

1/4

16

40

 -

Stainless Steel

1/16 - 1/8

11

30

 - 

Stainless Steel

3/16 - 1/4

13

32

 -

Copper

1/16 - 1/4

15

38

 -

Magnesium 

1/16 - 1/8

10

25

 -

Source

What is the best gas for TIG welding?

TIG welding is generally a slower more arduous process but provides better results on non-ferrous metals.

Although more complex, TIG welding offers the welder more control and allows for higher quality welds that are stronger.

Argon is the normal gas used for TIG welding however Helium can also be used or a blend of the two.

Helium is often added to Argon to increase the fluidity of the weld pool and allow for increased penetration of the weld.

Mixtures of Argon and Helium are suitable to be used in most welding grades. Helium has a higher thermal conductivity which helps provide a tighter, smother weld and fusion.

Experimenting with different welding gas mixtures will give you an idea of what works for you.

Using higher percentages of Helium will allow smoother welding bead for a neat and tidy finish.

Standard MIG welders that use welding gas, generally provide stronger welds. The weld join is less likely to be corrupted by corrosion or impurities.

A no-gas or flux welder can be used outdoors in windy conditions where a traditional gas welder may not be appropriate.

Flux welders are also easier to use for beginners and are more convenient for small and quick jobs.

Find out more about welding safety measures

What are the different types of welding gases?

  • Argon (Ar) Can be used 100% pure or combined with other gases depending on the application. Argon is suitable for both MIG and TIG welders.
  • Carbon Dioxide (CO2) Commonly used in combination with Argon or Helium as an inert shied for mild steel.
  • Helium (He) Is versatile as it can be used for a wide range of metals including aluminium, copper and stainless steel. Helium works to prevent contamination and as an inert shield.
  • Hydrogen (H2) Can be combined with Argon for welding high temperature metals like stainless steel.  
  • Nitrogen (N2) Although not a common welding gas, Nitrogen can be used in combination with Argon for use on stainless steel.

Source

What kind of gas do you use to weld stainless steel?

For Metal Inert Gas Welding

What type of gas mixture you use depends on the type of welder you have.

For MIG welding a mixture of between 2% and 20% Carbon Dioxide mixed with Argon or Helium will provide a good weld arc.

Do not use 100 % pure Argon or Helium for MIG welding. Ideally a mix of 90% Helium, 7.5% Argon and 2.5% Carbon Dioxide will produce the best results.

For Tungstun Inert Gas Welding

For a TIG welder however 100% Argon, 100% Helium or a mix of Argon and Helium is suitable for welding stainless steel and other metals.

Before you begin welding it is important to clean the areas that you want to join.

Using a wire brush, gently brush away any dirt, rust or burrs that will weaken the weld.

Pre-heating the area is recommended if the steel is high in carbon, and applying heat again after the weld has been made will help prevent the steel from cracking.

What is the best gas for MIG welding mild steel?

The most common gases used for MIG welding are Carbon Dioxide and Argon. Carbon Dioxide can be used on its own without needing to add an inert gas. Carbon Dioxide is a budget friendly gas being one of the cheaper shielding gases available.

Although a cheaper option, Carbon Dioxide alone may result in chunky weld pattern. For a smoother bead, flatter weld pool and less splatter try adding 15% to 25% Argon. A tri-mix of Helium, Argon and Carbon Dioxide can also be used and will give great results but is also a more expensive option.

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