Shielding Gas Basics

Shielding Gas Basics

Welders have been using shielding gas since the early 1920s when scientists first used external gas applied around the arc. This discovery of welding shielding gas laid the foundation for modern welding that we know today.

What Are Shielding Gases?

Shielding gases are the inert or semi-inert gases that protect the weld area from oxygen, water vapor and other harmful atmospheric gases that could potentially damage the weld.

An inert gas, such as Argon and Helium, is a non-reactive gas that does not chemically combine with other elements. These gases serve as a protective barrier of the welding arc to protect the molten weld metal against contamination from the atmosphere until it freezes.

Semi-inert gases, such as Hydrogen, Nitrogen, Oxygen, and Carbon Dioxide, are active shield gases. These gases, if used in large quantities, can damage the weld, but when used in controlled quantities, they can come together to improve the quality of the weld.

Why Are Shielding Gases Important?

The main purpose of shielding gas is to protect the weld from exposure of harmful atmospheric gases. The reaction of these elements with the weld pool can cause a variety of problems, such as porosity (holes within the weld bead), excessive spatter, and other defects.

Choosing the Right Shielding Gas

Choosing the right shielding gas requires extensive research of the type of welding you’re doing. Here’s what you need to know about the six basic types of shielding gases used in welding:


Argon is an inert gas that stays stable when used at high temperatures. Argon provides a unique welding atmosphere that pushes away other gases from the welding puddle. Argon also provides easier starts in alternating current applications as well as longer arcs at lower voltages. In pure form, Argon is best used when welding non-ferrous metals, such as Aluminum, Magnesium, or Titanium. Though Argon is the most widely-used shielding gas in welding, it is not widely used in welding steel or overhead welds due to its density.


Helium is an inert gas that provides a broader penetration profile, which works best when welding thick materials. Helium creates a hotter arc, which allows for faster travel and high productivity rates. Like Argon, pure Helium is typically used with non-ferrous metals, but also with stainless steel.


Hydrogen is a semi-inert gas often used with other gases in high temperature applications to increase arc stability and weld bead performance. Typically, Hydrogen is the element you are trying to get out of your weld pool. If used incorrectly, Hydrogen can cause weld porosity, a defect caused by too much trapped gas.


Like Hydrogen, Oxygen is generally used in combination with other gases. Oxygen is a reactive gas to improve weld pool fluidity, penetration, and arc stability. Oxygen causes oxidation of the weld metal; however, it cannot be used with non-ferrous metals.

Carbon Dioxide (CO2)

Carbon dioxide is the most common reactive gas used in welding. CO2 is the only element that can be used in its purest form without the addition of an inert gas. CO2 provides very deep weld penetration, which is best when working with thick materials. However, CO2 produces a lot of spatter, fumes, and shakier arcs.


This semi-inert gas makes up most of our atmosphere. Like other semi-inert gases, Nitrogen is best used when combined with other gases. Nitrogen increases arc stability and weld penetration. Gas blends containing Nitrogen can increase mechanical properties and prevent pitting corrosion from the metal.

Contact Atlas Welding Supply for your Shielding Gas Needs

With decades of experience in shielding gas and welding applications, we are confident we can be your trusted partner for everything from supplying the appropriate shielding gas, troubleshooting equipment, or providing customized solutions for your project for maximum efficiency. Contact us today to request a solution.

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