How to MIG Weld with Argon?

Argon is one of the most commonly used shielding gases for MIG welding. To weld with argon, you’ll need the proper equipment like a chain to secure the cylinder, gauges, and a contact tip sized for argon’s density. Set the argon flow rate based on your machine’s specs, usually 15-25 CFM. Use 100% argon for non-ferrous metals like aluminum under 1/2″, or add 25-75% helium for thicker sections. For steel, mix 75-95% argon with CO2. Wear ventilation and follow all safety precautions. Argon improves stability for spray transfer and out-of-position welds. Challenges include poor penetration on thick metals with 100% argon.

Welding with the proper shielding gas is critical for strong, defect-free welds. For MIG welding, argon is one of the most versatile and commonly used options. This inert gas provides excellent arc stability, low spatter, and good weld appearance on a wide range of metals.

However, argon isn’t a one-size-fits-all solution. Using the wrong type or mixture of shielding gas for your application can lead to frustrating defects. By understanding when and how to use argon for MIG welding, you’ll avoid headaches and achieve optimal weld quality.

How to Set Up Argon for MIG Welding

Before you can start laying down welds, you’ll need to get your machine fitted with the right argon cylinder, regulators, hoses, and accessories. Here’s an overview of what’s required:

Cylinder and Securing Chain

  • Argon welding gas cylinders are available in a range of sizes from 20 CF up to 300 CF capacity. Bigger tanks are preferable for high argon usage to avoid constantly swapping empties.
  • Secure the cylinder with a chain to prevent tipping or falling. Gas cylinders can easily turn into dangerous projectiles if knocked over.


  • Accurate gas pressure and flow rate gauges are vital. Replace old or damaged gauges that could give false readings.
  • Securely attach gauges to the regulator and check for leaks. Tighten connections as needed to prevent argon waste.

Contact Tip

  • Use a contact tip designed for argon’s density. Common sizes are 1/4″ or 1/8″ recess. Match your wire diameter.
  • Consult your welder manual or manufacturer website to select the right argon contact tip. An improper fit will affect arc length.

Hoses and Fittings

  • Confirm hoses, torch fittings, and consumables are rated for argon. Defective seals or holes can lead to shielding gas leaks.
  • Inspect and replace worn parts regularly before assuming poor shielding is an argon flow issue.


  • A flowmeter gauge makes it easy to set and monitor argon flow rate. Some machines have built-in regulators instead.
  • Verify flowmeter accuracy if weld problems persist despite adequate indicated argon flow. Faulty meters do occur.

Leak Testing

  • Always leak test your argon setup initially and periodically by brushing soapy water on connections and watching for bubbles while gas flows.
  • Tighten fittings or replace leaky hoses immediately to prevent wasting expensive argon gas.

Setting Argon Gas Flow Rate

Choosing the right argon flow rate for stable shielding without turbulence is key. As a rule of thumb:

  • Start with 15-20 CFM for a typical shop environment and medium-sized nozzle.
  • Go up to 30-40 CFM for drafty conditions or a larger torch nozzle.
  • Too high of a flow rate can create turbulence and air entrapment in the weld.

However, your machine manufacturer’s recommendations will be the most accurate for your specific model. Many welders have an argon flow rate chart right on the machine.

For aluminum, flow rates of:

  • 20-30 CFM are typical for 100% argon shielding.
  • 30-40 CFM for argon/helium mixes on thicker aluminum.

On steel, a 75/25 argon/CO2 mix will require around 20-25 CFM.

The actual optimum rate depends on factors like:

  • Nozzle size
  • Joint type
  • Base metal thickness
  • Wire speed/amps

Take the time to test different argon flow settings on scrap pieces to dial in the best rate. Watch the weld pool shape and sound for cues.

Choosing the Right Argon Contact Tip

The argon gas flows between the contact tip and nozzle to surround the weld, so sizing is important.

Since argon is denser than other shielding gases:

  • A longer contact tip recess is required so the wire stickout length is correct.
  • Typical sizes are 1/4″ or 1/8″ recess length.

To prevent arc wandering and instability:

  • Match the tip diameter to your wire size, usually printed on the tip.
  • Consult your welder manual’s contact tip chart for argon.
  • Use the tip specifically made for your machine model if possible.

The goal is proper wire extension – too much stickout increases voltage and destabilizes the arc.

Protecting Yourself from Fumes

Though argon gas itself is non-toxic, welding produces harmful fumes that require protection:

  • Work in a well-ventilated area to allow fumes to dissipate.
  • Use a fume extractor system or portable exhaust fan to capture fumes directly at the arc.
  • Wear an approved respirator if ventilation is insufficient.
  • Avoid confined spaces where argon and fumes can accumulate.

Prioritize exposure controls, ventilation, and PPE to stay safe when MIG welding with argon shielding. Don’t rely on the gas alone to protect you.

Storing Argon Gas Cylinders

Though non-flammable, argon cylinders still require proper handling:

  • Keep cylinders chained upright to prevent tipping or falls.
  • Store in a dry, well-ventilated area away from heat sources.
  • Avoid temperatures exceeding 125°F (52°C).
  • Move with a hand truck, not by rolling, dragging, or carrying alone.
  • Replace caps when not in use and close valves when empty.

By following safety best practices, argon gas cylinders won’t pose unnecessary hazards in your shop. Handle with care at all times.

Argon Cylinder Duration

With a standard 250 CF argon cylinder and 15-20 CFM flow rate, expect approximately:

  • 10 hours of continuous MIG welding runtime.
  • 1 week of runtime for occasional/intermittent welding.
  • Faster depletion with higher flow rates or larger nozzles.
  • Less usage time from a smaller cylinder (125 CF, etc.)

Mark your start date on tanks to track when a refill will be needed. Most suppliers do argon refills on-site.

And with an indefinite shelf life when stored properly, argon won’t go “stale” from sitting too long unused.

When to Use 100% Argon Gas

Pure argon as a shielding gas has some specific benefits and limitations:

For Aluminum and Non-Ferrous Metals

  • Argon provides good cleaning action to remove oxides from aluminum and other non-ferrous surfaces.
  • The inert gas prevents discoloration or weak welds from reactions with reactive metals.
  • Use 100% argon for thin aluminum sheet/plate, up to approximately 1/2″ thickness.

Adds Stability for Spray Transfer Welding

  • Argon helps produce a consistent, spatter-free metal transfer in axially spray arc welding.
  • Neither pure CO2 nor helium alone provides a controlled spray transfer mode.

Better Penetration Control for Fillet and Butt Welds

  • Compared to CO2, argon provides a less penetrating weld profile that lends itself well to certain joint types.
  • The lower penetration helps prevent burn-through and overwelding on thin materials.

For Welding Out-of-Position

  • Argon’s inert properties reduce issues with the weld pool dripping or falling when welding overhead or in incline positions.
  • Gravity won’t pull the weld puddle away as much before it solidifies.

Blending Argon with Other Gases

Though useful on its own, argon is often blended with oxygen, helium, or carbon dioxide:

Argon-Helium Mixtures

  • For aluminum thicker than 1/2″, add 25-75% helium to argon.
  • Increases penetration and welding speed from the hotter arc.
  • More prone to burn-through if technique isn’t adjusted.

Argon-Oxygen Blends

  • Adding 1% oxygen stabilizes the arc for aluminum pulsed MIG welding.
  • The oxygen boosts electron flow across the arc.
  • Oxygen also helps stiffen the weld puddle for out-of-position use.

Argon-Carbon Dioxide Mixes

  • For steel, mix 75-95% argon with balance CO2, such as C25 (25% CO2).
  • Carbon dioxide increases weld penetration over pure inert argon.
  • Reduces spatter compared to 100% CO2 shielding.

Challenges When Using 100% Argon

While versatile, 100% argon gas can present some welding difficulties:

Poor Arc Stability on Steel

  • Using pure argon on steel causes arc wandering from insufficient ionization.
  • The CO2 or O2 helps conduct electrons across the arc.
  • Possible to weld steel with 100% argon, but more tedious and higher reject rate.

Lack of Penetration on Thick Metals

  • Argon’s lower thermal conductivity limits how much heat gets delivered into the workpiece.
  • On metals over 1/2″ thick, argon/helium mixes give deeper penetration.
  • Helium additions add heat to melt through heavier plates.

Risk of Incomplete Fusion Defects

  • Full-penetration welds are harder with just argon shielding gas.
  • Corners of a weld may be cold-lapped and unmelted without supplemental gases.
  • Adding some oxygen or carbon dioxide improves heat delivery.

Best Practices for Welding with Argon Gas

Follow these tips when MIG welding to get the most out of your argon shielding:

  • Maintain clean, dry argon hoses and torch fittings to prevent porosity from leaks.
  • Adjust wire speed and stickout to reduce spatter if needed when using pure argon.
  • Watch for inadequate penetration on thick metals and increase preheat if needed.
  • Use a welding glove or pliers to remove contact tips; they get hot!
  • Check argon flow periodically by listening for a steady hissing sound around the nozzle.
  • Keep a stack of spare contact tips handy for when they wear out or melt.
  • Don’t weld in the direct path of fans or drafts which can disrupt shielding gas coverage.
  • For out-of-position use, increase argon flow rate to compensate for rising heat.
  • Slow down on welding speed for better results than trying to go fast with argon.
  • Clean aluminum with stainless wire brush or chemical bath before welding to enhance argon’s action.

Pro Tip: Lower your electrode stickout to 3/8” or less when using 100% argon for a tighter arc and smoother bead profile.

Editor’s Note: Consider an argon/CO2 mix if you’ll be welding steel outdoors where wind causes shielding gas turbulence. The CO2 provides some protection if argon coverage gets disrupted.

Frequently Asked Questions

Can you MIG weld steel with 100% argon gas?

While possible, using pure argon to weld steel causes arc instability and results in brittle, weak welds prone to cracking. Always use a CO2 or O2 blend for steel. An argon-CO2 mix like 75/25 is strongly recommended over pure argon.

Is argon or CO2 better for MIG welding?

Argon works well for non-ferrous metals like aluminum and produces a nice light arc. CO2 offers good penetration on steel but causes more spatter. Blends like 75% argon/25% CO2 give a good balance of benefits by combining the two gases.

Why is argon used for welding?

Argon’s inert properties prevent oxidation and contamination during welding, enabling quality welds on reactive metals like aluminum and magnesium. Argon also provides good arc stability and minimal spatter. Adding argon to active gases like CO2 enhances their performance.

Does argon make stronger welds?

When used correctly on the proper base metal, argon shielding allows for strong, ductile welds. The smooth, inert gas coverage prevents defects like porosity. However, argon’s lower penetration capability can limit strength on thicker sections compared to CO2 blends.

Should I use 100% argon for aluminum?

For thin aluminum under 1/2″ thick, 100% argon works very well and provides the best cleaning action on the metal. For thicker aluminum welds, add 25-75% helium to the argon to boost penetration. The argon still shields the metal, while the helium adds heat.


With the right techniques and settings, argon can provide bubble-free, spatter-free welds on a wide range of metals. It does require using the proper flow rate, recess length contact tips, and gas mixtures tailored for your specific application.

Understanding argon’s strengths and limitations allows you to take full advantage of this popular shielding gas. Preventing weld defects means considering factors like base metal thickness, joint type, and welding position.

While inert gases make welding easier, don’t neglect safety! Always wear approved eye and breathing protection and work in a well-ventilated environment.

We hope this guide gives you confidence in setting up your MIG welder for argon and achieving the highest quality welds possible. Let us know if you have any other questions!

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