What is the purpose of slag removal during welding?

• A. Prevents slag inclusions and ensures clean weld surface for bonding.
• B. Improves porosity by trapping air.
• C. Strengthens the slag itself for better support.
• D. Reduces the need to clean the base metal.

Answer: (A)

Slag removal is essential because slag is a byproduct that forms a protective layer over the weld as it cools. If this layer isn’t chipped away, slag can become trapped in the weld or leave a dirty surface, leading to slag inclusions and poor fusion. That directly weakens the weld and can cause defects in subsequent passes, making bonding to the base metal unreliable.

Removing slag exposes a clean weld surface, which allows proper fusion between the filler and base metal and makes it easier to inspect and ensure a quality bond. This step also helps prevent defects that would arise if slag were left on the weld.

The other ideas don’t fit because slag isn’t there to trap air to improve porosity, and it doesn’t strengthen itself to support the weld. Nor does slag removal eliminate the need to clean the base metal; cleaning is still important, but slag removal specifically ensures a clean surface for sound bonding and defect-free welds.