What does "hollow bead" refer to in welding?

• A. A type of weld joint
• B. A linear porosity defect
• C. A welding technique
• D. A type of filler metal

Answer: (B)

The term "hollow bead" specifically refers to a type of defect characterized by linear porosity within a weld. This defect occurs when gas pockets become trapped in the weld metal during the solidification process, leaving voids that can weaken the joint. The presence of hollow beads indicates inadequate fusion or improper welding parameters that fail to create a sound weld.

In the context of welding quality, understanding this defect is crucial as it can significantly affect the structural integrity of the welded assembly. Factors contributing to hollow beads might include poor shielding gas coverage, incorrect travel speed, or insufficient preheat. Hence, recognizing hollow beads during inspection is vital for ensuring the reliability of welded structures.

The other options do not accurately represent a "hollow bead." A type of weld joint is a structural configuration and does not address defects. A welding technique involves the method or procedure used during welding, while a type of filler metal is about the material used to fill the weld joint, none of which directly relates to the porosity issue described by "hollow bead."