What is porosity in welding terms?

• A. Bubbles of gas trapped inside the weld
• B. Hydrogen concentration in the weld metal
• C. Cracks in the weld
• D. Excess filler metal

Answer: (A)

Porosity in welding is tiny gas pockets trapped in the weld metal as it solidifies. These gas bubbles appear as small voids and can weaken the joint. They form when shielding gas coverage is insufficient, contaminants or moisture are present on the base metal or electrode, or gas is released during solidification. Hydrogen can contribute to porosity if it enters the weld, but porosity itself is defined by the trapped gas pockets. Cracks are a different defect, and excess filler metal refers to weld reinforcement rather than porosity.