Argon is the most common gas for TIG welding carbon steel. How to TIG weld Carbon steel and TIG Welding Carbon Steel Gas Q&A

Simple TIG Welding Settings using Argon Gas

Argon is the best choice for TIG Welding Carbon Steel.

C25 gas (75% argon / 25% CO₂) should not be used for TIG welding carbon steel for several key reasons:

🔧 1. TIG Welding Requires a Non-Reactive Shielding Gas

• Argon is inert, meaning it does not react with the molten metal.
• C25 is for MIG welding. It contains CO₂, which is reactive and will cause problems in TIG welding:
• C25 mig gas can introduce oxidation and contaminants. It sparks and spews with TIG
• It leads to an unstable arc and more spatter, which is completely undesirable in TIG.
• C25 gas erodes tungsten quickly
• C25 gas will make you cuss and give up tig welding 

🔥 2. Argon Allows for Stable Arc Performance

• Pure argon ensures a smooth, stable arc.
• Stable arc = better control, especially for thin materials or precise joints.

🧪 3. Tungsten Electrode Protection

• Argon fully shields the tungsten electrode, preventing oxidation.
• CO₂ in C25 can react with the tungsten, leading to:
• Contaminated tungsten.
• Arc instability.
• More frequent regrinding.

📌 Conclusion:

Use 100% argon for TIG welding carbon steel.
C25 is designed for short-circuit MIG welding and will cause serious issues if used with TIG — like dirty welds, arc instability, and tungsten contamination.

What to do if you think you have a bad tank of argon

Cylinder mislabeling can happen, and using C25 instead of pure argon can ruin a TIG weld. Here are some quick easy ways to tell if a mislabeled "argon" cylinder is actually C25 (75% argon / 25% CO₂):

✅ 1. Watch the Arc Behavior

If you suspect the gas is not pure argon, do a quick TIG arc test:

👉 If it acts like MIG, not TIG, it’s probably C25.

🔥 2. TIG Torch Test with No Filler

• Set up a DCEN TIG weld on clean carbon steel.
• Strike an arc and hold a puddle for a few seconds with no filler.
• Look for:
• Smooth, shiny puddle → ✅ likely pure argon.
• Aggressive puddle, rapid oxidation, blackened edges → ❌ likely C25.

🧪 3. Look at the Weld Surface After Cooling

• Pure argon: the weld and heat-affected zone should stay shiny or lightly straw-colored.
• C25: surface turns gray, black, or sooty—clear sign of CO₂ contamination.

Corner Joint, Lap Joint, Tee Joint with Settings and Arc shots

see video on how to tig welding carbon steel tubing

This Video Shows Tips and Techniques for How to TIG Weld Carbon Steel, Stainless, Aluminum, and Titanium

How to Identify what type TIG torch you have...( don't worry, there are only 2 main styles of TIG torches)

When it comes to TIG torch parts, there are only 2 main types of TIG torches...#17, 18, 26  are one type.  

And #9 and 20 are the other type

So all you need to do is take a look at your current TIG torch and see which collet body matches the photos above and then order either a kit for 17,18,26 style torch or a kit for #9 and 20 TIG torch.

The first video on this page is a short and concise video on tig welding weld carbon steel settings  

When you use a foot pedal with a primeweld tig welder, the settings become very simple. 

TIG Welding Carbon Steel with Argon Gas using ER70S-6 for the root and hot pass