Shielding gas protects the weld from gases that cause what?

Shielding gas protects the weld from gases that cause what?

• A. Thermal cracks
• B. Porosity
• C. Oxidation
• D. Slag Inclusions

Answer: (B)

Shielding gas creates a protective blanket around the arc and molten weld so atmospheric gases don’t reach the weld pool. When air leaks in or shielding is insufficient, gases like oxygen and moisture can mix with the molten metal and become trapped as the weld solidifies. Those gas pockets form porosity, which weakens the weld and can cause leaks in joints. While shielding gas also helps reduce surface oxidation, the defect most directly tied to the presence of atmospheric gases in the weld is porosity, making it the best answer.

Shielding gas creates a protective blanket around the arc and molten weld so atmospheric gases don’t reach the weld pool. When air leaks in or shielding is insufficient, gases like oxygen and moisture can mix with the molten metal and become trapped as the weld solidifies. Those gas pockets form porosity, which weakens the weld and can cause leaks in joints. While shielding gas also helps reduce surface oxidation, the defect most directly tied to the presence of atmospheric gases in the weld is porosity, making it the best answer.