What is slag, and how does slag inclusion occur?

What is slag, and how does slag inclusion occur?

• A. Slag is a protective gas layer; slag inclusions occur when gas pockets form during welding.
• B. Slag is the molten metal itself; slag inclusions occur when the weld bead cools too quickly.
• C. Slag is flux-derived scoria that blankets the weld; slag inclusions happen when slag is trapped in the weld due to improper slag removal or poor technique.
• D. Slag is a filler metal; slag inclusions occur due to excessive filler metal deposition.

Answer: (C)

Slag is the flux-derived scoria that blankets the weld during processes that use flux. It forms from the flux reacting with oxides and impurities, then cools into a glassy layer that protects the molten metal and helps set the weld chemistry. Slag inclusions occur when this material is trapped in the weld instead of being removed. This happens if you don’t chip away or clean the slag between passes, or if you weld through a layer of slag or fail to properly control slag buildup. The result is a defect inside the weld that can compromise strength. Slag is not a protective gas layer, nor is it the molten metal itself or the filler metal; it’s the byproduct of the flux that should be removed after each pass.

Slag is the flux-derived scoria that blankets the weld during processes that use flux. It forms from the flux reacting with oxides and impurities, then cools into a glassy layer that protects the molten metal and helps set the weld chemistry. Slag inclusions occur when this material is trapped in the weld instead of being removed. This happens if you don’t chip away or clean the slag between passes, or if you weld through a layer of slag or fail to properly control slag buildup. The result is a defect inside the weld that can compromise strength. Slag is not a protective gas layer, nor is it the molten metal itself or the filler metal; it’s the byproduct of the flux that should be removed after each pass.