What is responsible for penetration in a welding circuit?

• A. Voltage
• B. Resistance
• C. Amperage
• D. Duty cycle

Answer: (C)

Penetration is driven by the heat delivered into the weld joint. The amount of heat produced by the arc increases with current, so higher amperage puts more energy into the weld pool, melting more base metal and producing deeper penetration. Voltage does affect arc shape and stability, but it doesn’t control how deeply the metal fuses as directly as the current does. Duty cycle deals with how long you can weld before the machine overheats, not how deep the weld penetrates. Resistance isn’t something you set to change penetration in typical welding practice. So, the amperage best explains why penetration changes.