Which statement correctly contrasts lack of penetration with lack of fusion in welds?

Which statement correctly contrasts lack of penetration with lack of fusion in welds?

• A. Lack of penetration means there is a crack at the weld; lack of fusion means the joint is overfilled.
• B. Lack of penetration means insufficient weld metal through joint thickness; lack of fusion means weld metal failed to fuse to base metal or previous beads.
• C. Lack of penetration means melt-through occurs; lack of fusion means there is porosity.
• D. Lack of penetration means weld metal fuses to base metal but not through thickness.

Answer: (B)

Penetration is about how far the weld metal fuses into the joint across its thickness. When penetration is lacking, the weld doesn’t extend through the full thickness of the joint, leaving part of the joint unfilled. Fusion, on the other hand, is about the weld metal bonding to the base metal or to previous weld beads. If the weld metal fails to fuse to the base metal or to earlier passes, that’s a lack of fusion, creating an unfused boundary. So the correct statement describes lack of penetration as insufficient weld metal through the joint thickness, and lack of fusion as weld metal failing to fuse to the base metal or previous beads. Other options describe different defects (cracks/overfill, porosity, melt-through) that don’t capture these two concepts.

Penetration is about how far the weld metal fuses into the joint across its thickness. When penetration is lacking, the weld doesn’t extend through the full thickness of the joint, leaving part of the joint unfilled. Fusion, on the other hand, is about the weld metal bonding to the base metal or to previous weld beads. If the weld metal fails to fuse to the base metal or to earlier passes, that’s a lack of fusion, creating an unfused boundary.

So the correct statement describes lack of penetration as insufficient weld metal through the joint thickness, and lack of fusion as weld metal failing to fuse to the base metal or previous beads. Other options describe different defects (cracks/overfill, porosity, melt-through) that don’t capture these two concepts.