A heavy duty equipment technician is performing a multi-pass GMAW repair on a thick carbon steel component. After the first pass, they notice significant undercut along the toes of the weld. What adjustment is most likely needed to correct this issue?

Question: A heavy duty equipment technician is performing a multi-pass GMAW repair on a thick carbon steel component. After the first pass, they notice significant undercut along the toes of the weld. What adjustment is most likely needed to correct this issue?

Answer options:

• Increasing the welding current.
• Decreasing the travel speed.
• Adjusting the torch angle to be more perpendicular to the joint. ✅ Slightly decreasing the voltage.

Correct answer: Slightly decreasing the voltage.

Explanation: Undercut in GMAW is often caused by excessively high voltage or too long of an arc, which can melt the base metal at the toes of the weld without filling it with filler metal. Slightly decreasing the voltage or shortening the arc length can help reduce undercut. Increasing current or decreasing travel speed typically increases heat input and penetration, potentially worsening undercut. Adjusting the torch angle to be more perpendicular might also exacerbate undercut if the angle isn't correct for the joint type.