What does the term "porosity" refer to in welding?

The term "porosity" in welding specifically refers to gas pockets or voids that become trapped within the weld metal during the solidification process. This phenomenon occurs when gases that are released during the melting of the base materials or from the filler material are unable to escape the molten weld pool before it solidifies. The presence of these voids can significantly impair the mechanical properties and integrity of the weld, leading to weaknesses that may result in failures under applied loads.

Porosity is a crucial defect to recognize and control within the welding process, as it can affect not only the strength but also the appearance of the weld. The detection of porosity is typically carried out through visual inspections or non-destructive testing methods, which help ensure the quality and reliability of the welded joints in various applications.

In contrast, other options such as excessive heat damage, incomplete fusion, and excessive spatter refer to different types of welding issues that can arise but do not accurately define porosity. Each of these other concerns has its own implications and corrective measures, thus highlighting the distinct nature of porosity as it pertains specifically to gas entrapment in welds.