What is the common cause of porosity in welding?

Porosity in welding refers to the presence of small voids or cavities within the weld metal, which can weaken the weld and lead to failure. The common cause of porosity is gas entrapment during solidification. This occurs when gases that are generated during the welding process—such as moisture, impurities, or shielding gas—become trapped in the molten weld pool and are unable to escape before it solidifies.

When the weld pool cools and solidifies too quickly, or if the conditions do not allow for proper gas escape, these gases can form bubbles that create porosity in the finished weld. This issue is more prevalent in certain environmental conditions or when there is contamination on the base materials or filler material. Hence, controlling the welding environment and ensuring proper technique are vital to prevent gas entrapment and subsequent porosity.