What is the main cause of undercut in welding?

• A. Inadequate welding speed.
• B. Excessive amps.
• C. Insufficient shielding gas.
• D. Improper electrode angle.

Answer: (B)

The main cause of undercut in welding is often linked to excessive amps. When the current is set too high, it can lead to localized melting of the base material alongside the weld joint. This over-melting can create grooves or depressions in the base material, known as undercut, where the weld metal fails to fill properly, resulting in a weaker joint.

While inadequate welding speed may contribute to other issues, it is not the primary factor that causes undercut. Insufficient shielding gas is more related to contamination issues rather than undercut formation. Similarly, an improper electrode angle impacts the shape and penetration of the weld but does not directly cause the groove characteristic of undercutting. Thus, excessive amps distinctly stand out as the primary cause due to its direct effect on melting the surrounding base material excessively.