How does increasing travel speed affect heat input and penetration in FCAW?

How does increasing travel speed affect heat input and penetration in FCAW?

• A. Heat input and penetration decrease
• B. Heat input increases
• C. Penetration increases
• D. Bead width increases

Answer: (A)

Increasing travel speed reduces the time the arc spends on any one spot, so the heat input per unit length drops. In FCAW, this lower heat input means the weld pool receives less energy, melts less material, and therefore the depth to which the weld penetrates the joint decreases. Since penetration is driven by how much energy is delivered to the joint, it goes down as travel speed goes up. Bead width is tied to heat input as well, and with less heat, the molten pool tends to spread less, so bead width generally does not increase. So both heat input per length and penetration decrease as travel speed increases.

Increasing travel speed reduces the time the arc spends on any one spot, so the heat input per unit length drops. In FCAW, this lower heat input means the weld pool receives less energy, melts less material, and therefore the depth to which the weld penetrates the joint decreases. Since penetration is driven by how much energy is delivered to the joint, it goes down as travel speed goes up. Bead width is tied to heat input as well, and with less heat, the molten pool tends to spread less, so bead width generally does not increase. So both heat input per length and penetration decrease as travel speed increases.