AC is generally not used with FCAW. Which statement best reflects this?

AC is generally not used with FCAW. Which statement best reflects this?

• A. True
• B. False
• C. Sometimes used
• D. Always used

Answer: (A)

In FCAW, the arc behavior and shielding depend on a fixed polarity, and direct current (usually with the electrode positive) provides a stable arc, predictable heat input, good deposition, and reliable penetration for the flux-cored wire. If you switch to alternating polarity every half cycle, as in AC, the arc becomes less stable and the flux chemistry changes with each half-cycle. This can lead to inconsistent shielding, slag formation/removal difficulties, and less controllable deposition and penetration, making the weld quality harder to predict. Because of that, AC is not the typical choice for FCAW, so the statement that AC is generally not used is true. There are rare, specialized cases where AC might be used, but they are exceptions rather than the rule.

In FCAW, the arc behavior and shielding depend on a fixed polarity, and direct current (usually with the electrode positive) provides a stable arc, predictable heat input, good deposition, and reliable penetration for the flux-cored wire. If you switch to alternating polarity every half cycle, as in AC, the arc becomes less stable and the flux chemistry changes with each half-cycle. This can lead to inconsistent shielding, slag formation/removal difficulties, and less controllable deposition and penetration, making the weld quality harder to predict. Because of that, AC is not the typical choice for FCAW, so the statement that AC is generally not used is true. There are rare, specialized cases where AC might be used, but they are exceptions rather than the rule.