When 1% - 9% oxygen is added to argon shielding gas, it is to:

When 1% - 9% oxygen is added to argon shielding gas, it is to:

• A. Reduce spatter.
• B. Increase the deposition rate.
• C. Improve wetting action.
• D. Reduce welding costs.

Answer: (C)

Adding a small amount of oxygen to argon shielding gas changes the arc chemistry just enough to make the molten weld pool flow better. That extra oxygen lowers the surface tension of the molten metal and helps break up oxide film on the surface, so the metal wets the base metal more effectively. The result is a smoother, flatter bead with better fusion to the joint. This is why improving wetting action is the most relevant effect of 1%–9% oxygen in argon. Spatter, deposition rate, and welding costs aren’t directly driven by this small oxygen addition in the way that wetting and bead contour are, so they aren’t the primary reason for using oxygen-enriched argon.

Adding a small amount of oxygen to argon shielding gas changes the arc chemistry just enough to make the molten weld pool flow better. That extra oxygen lowers the surface tension of the molten metal and helps break up oxide film on the surface, so the metal wets the base metal more effectively. The result is a smoother, flatter bead with better fusion to the joint.

This is why improving wetting action is the most relevant effect of 1%–9% oxygen in argon. Spatter, deposition rate, and welding costs aren’t directly driven by this small oxygen addition in the way that wetting and bead contour are, so they aren’t the primary reason for using oxygen-enriched argon.