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Welding Gases For Shielding MIG Welding

Welding gases like Argon, Helium, Carbon Dioxide, and Oxygen are used in Metal Inert Gas (MIG) welding, to prevent the welding material from oxidizing, which ruins the weld. If you remember chemistry class, you may have noticed that Carbon Dioxide and Oxygen are not, in fact, inert gases. In the beginning, MIG used only Argon and Helium as welding gases, but it was later discovered that both Carbon Dioxide and Oxygen were useful for MIG welding in some applications, so this form of welding is now officially named Gas Metal Arc Welding (GMAW, for short), though many, many welders still call it MIG.

The Right Gas For The Application

MIG welding is one of the easiest forms of welding to learn, because the gun includes a feeder for the wire filler material, which pulls wire off a spool and runs it out through the heated tip of the gun, which, of course, melts it into the weld puddle. It is this puddle that has to be protected from the ambient atmosphere with a shield gas, so that it does not oxidize as it cools. The shield gas flows from the gun to keep defects from forming in the cooling weld puddle.

  • Carbon Dioxide – Carbon Dioxide, though it is a reactive gas, can be used in its pure form as a shield gas, and it is relatively inexpensive. It is only useful for short-circuit GMAW welding in its pure form, and it tends to spatter more and make a less stable arc than it does when mixed with an inert gas like Argon. Pure CO2 gives deep weld penetration, so it is good for welding thicker material.
  • Argon – Pure Argon gas is a good choice for welding non-ferrous metals, like Aluminum, Magnesium, or Titanium. Because Argon produces a narrower penetration profile, it works well for fillet and butt welds.
  • Helium – Helium is also used for welding Aluminum, Magnesium, Titanium, and stainless steel, as well. Helium is almost always used in a mixture with other gases. Helium creates a hotter arc than Argon or CO2, and it gives a wide, deep penetration profile, which varies depending on the mix, so it is useful in welding thick material. The hotter arc allows for faster travel and greater productivity, but helium requires a higher flow rate than argon and is more expensive.
  • Oxygen – It defies logic that Oxygen is used in a shielding gas mix to prevent oxidizing, but it has its uses. Typically, Oxygen is used in a concentration of 9% or less, because it improves the fluidity of the weld puddle, the penetration, and the arc stability when welding mild carbon, low alloy, or stainless steel. It does, in fact, cause some oxidizing, so it is not used with Aluminum, Magnesium, Copper, or other exotic metals.

Need An Expert Opinion?

At Josef Gas, you don’t just get a salesman; you get a representative who is actually an experienced welder. If you need advice on what gas or mix to use for your application, give us a call at 416-658-1212. We’re happy to help you choose the right welding gases and supplies.

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