What is the role of slag in FCAW/MCAW welding, and what must be done between passes?

Study for the Gas Metal Arc Welding Exam, including GMAW, FCAW, and MCAW methods. Use flashcards and multiple choice questions with hints and explanations for effective learning. Get ready for your welding certification!

Multiple Choice

What is the role of slag in FCAW/MCAW welding, and what must be done between passes?

Slag in FCAW/MCAW acts as a protective flux-derived layer that shields the molten weld pool from the atmosphere as you weld. It also forms a crust as it solidifies. But for multiple passes, that slag must be removed between passes. Chipping or brushing away the slag exposes the underlying weld so the next bead can wet out and fuse properly with the previous layer. If slag is left in place, the next pass won’t fuse correctly, leading to poor fusion, porosity, or slag inclusions. Slag isn’t a permanent protective layer for the finished weld—its shielding role is during welding, and proper cleaning between passes is essential for sound multi-pass welds.

Slag in FCAW/MCAW acts as a protective flux-derived layer that shields the molten weld pool from the atmosphere as you weld. It also forms a crust as it solidifies. But for multiple passes, that slag must be removed between passes. Chipping or brushing away the slag exposes the underlying weld so the next bead can wet out and fuse properly with the previous layer. If slag is left in place, the next pass won’t fuse correctly, leading to poor fusion, porosity, or slag inclusions. Slag isn’t a permanent protective layer for the finished weld—its shielding role is during welding, and proper cleaning between passes is essential for sound multi-pass welds.

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