AWS Certified Welding Inspector — FundamentalsNondestructive Examination (NDE)Easy
A CWI is performing a visual inspection (VT) on a fillet weld. The weld exhibits an uneven flow of weld metal, resulting in a concave bead profile and the weld toe not meeting the specified weld size. This condition is commonly known as:
- AOverlap.
- BLack of fusion.
- CUndercut.
- DUnderfill.
Show answer & explanationAnswer & explanation
Correct answer: D. Underfill.
Underfill is a weld discontinuity characterized by a depression on the weld surface or root surface, below the adjacent base metal surface. In a fillet weld, this often manifests as a concave profile where the weld metal does not reach the specified size or fill the joint adequately.
Why the other options are wrong
- A. Overlap is when weld metal extends beyond the toe or root of the weld.
- B. Lack of fusion is a discontinuity between the weld metal and base metal or between adjacent beads.
- C. Undercut is a groove melted into the base metal adjacent to the weld toe or root and left unfilled by weld metal.
VT - Underfill
Underfill is a weld discontinuity where the weld face or root surface is below the adjacent surface of the base metal, often resulting in a concave profile in fillet welds.
- Weld metal insufficient to fill joint.
- Surface depression below base metal.
- Reduces weld throat or leg size.
- Common in fillet welds with concave profile.
Memory trick: Look for the highs and lows, the gaps and overlaps.