AWS Certified Welding Inspector — FundamentalsNondestructive Examination (NDE)Easy
A CWI is tasked with performing a visual inspection (VT) on a newly completed fillet weld for a structural steel component. Which of the following discontinuities is considered a linear discontinuity?
- AUndercut
- BCrater pipe
- CIncomplete fusion
- DPorosity
Show answer & explanationAnswer & explanation
Correct answer: A. Undercut
Undercut is a linear discontinuity that appears as a groove melted into the base metal adjacent to the toe or root of a weld and left unfilled by weld metal. Porosity, crater pipes, and incomplete fusion are typically volumetric or planar discontinuities, not linear in the context of visual inspection.
Why the other options are wrong
- B. Crater pipe is a volumetric discontinuity, often spherical or irregular, at the end of a weld bead.
- C. Incomplete fusion is a planar discontinuity, not linear in the typical visual sense.
- D. Porosity is a volumetric discontinuity, not linear.
Linear Discontinuity (VT)
A discontinuity whose length is significantly greater than its width, appearing as a line or elongated mark during visual inspection.
- Examples include cracks, undercut, and lack of penetration.
- Often more critical than volumetric discontinuities due to stress concentration.
- Detected visually by observing distinct elongated features.
Memory trick: Lines are long, points are short, planes are flat.