An excessively low voltage leads to which effects?

• A. A high narrow bead; unstable arc; difficult slag removal
• B. A flat bead with good penetration
• C. Increased slag production
• D. Improved arc stability

Answer: (A)

Voltage controls arc length and heat input in an arc weld. When voltage is too low, the arc becomes very short, concentrating heat in a smaller area. That makes the weld bead high and narrow because the molten pool can’t spread out as much, and the rapid cooling tends to keep the bead tall. The arc is also less stable with a very short gap, so fluctuations and interruptions are more likely, giving an unstable arc. Slag removal becomes difficult because the surface slag forms a crust that doesn’t get adequately reheated or scoured by the weld pool, making it adhere more stubbornly. In short, an excessively low voltage produces a high, narrow bead, unstable arc, and harder slag removal.