What is porosity in a weld and two common causes?

• A. Porosity is gas pockets within the weld metal; caused by moisture in electrodes and shielding gas issues.
• B. Porosity is surface rust on the weld.
• C. Porosity is deep cracks in the weld.
• D. Porosity is color tint due to heat.

Answer: (A)

Porosity is gas pockets trapped inside the weld metal as it solidifies. These voids weaken the weld and can show up as holes or a bubbly-looking area in nondestructive tests.

Two common causes are moisture in the electrode coating, which releases hydrogen into the molten weld and forms gas pockets, and shielding gas issues, such as leaks or contaminated gas, that allow air to enter the weld pool during shielding. Keeping electrodes dry, storing them properly, and ensuring the shielding gas system is clean, leak-free, and delivering the correct flow help prevent porosity.