Argon — What It Is and Why It Matters
Argon is an inert (chemically non-reactive) gas that is the foundation of most welding shielding gas applications. It is the exclusive shielding gas for TIG welding and is used pure or in blends for MIG welding on aluminum, stainless steel, and other non-ferrous metals.
Argon's inert nature means it does not react with the molten weld pool, providing clean, contamination-free shielding. Its relatively high density (heavier than air) provides good gas coverage over the weld zone. For MIG welding mild steel, argon is blended with CO2 (typically 75/25) to add arc energy — pure argon alone produces a cold, erratic arc on steel.
Argon is supplied in compressed gas cylinders at approximately 2,200 PSI when full. Standard cylinder sizes include 40, 80, and 125 cubic foot bottles for shop use, with 300+ cubic foot bottles for high-volume production. A typical 80 CF bottle provides 8-10 hours of TIG welding at 15 CFH flow rate.
Frequently Asked Questions
Can I use pure argon for MIG welding steel?
Technically yes, but the results are poor. Pure argon on steel produces an unstable arc with an erratic, finger-like penetration pattern and an unattractive bead. Adding CO2 (at least 10-25%) or using an argon-CO2 blend stabilizes the arc and produces proper spray or short-circuit transfer.
How long does a tank of argon last?
It depends on flow rate and welding hours. An 80 cubic foot tank at 15 CFH flow rate provides roughly 5+ hours of continuous welding. At 20 CFH, that drops to about 4 hours. For hobby use with intermittent welding, a tank can last weeks or months.