AWS Certified Welding Inspector — FundamentalsNondestructive Examination (NDE)Medium
A CWI is reviewing a radiographic film for a 0.5-inch thick aluminum weld. The film shows a dark, distinct, and elongated indication with irregular edges, located entirely within the weld bead. This indication is oriented randomly, not consistently parallel or perpendicular to the weld axis. What type of discontinuity does this MOST likely represent?
- AUndercut.
- BIncomplete penetration.
- CSlag inclusion.
- DPorosity.
Show answer & explanationAnswer & explanation
Correct answer: C. Slag inclusion.
Slag inclusions typically appear as dark, irregular, elongated indications on radiographs, often with fuzzy or distinct edges, and can be randomly oriented within the weld. They are usually darker than the surrounding weld metal due to their lower density, allowing more radiation to pass through.
Why the other options are wrong
- A. Undercut appears as a dark line or lines at the toe of the weld along the fusion line, typically on the outside edges of the weld image.
- B. Incomplete penetration appears as a straight, continuous, dark line along the root of the weld.
- D. Porosity appears as rounded or spherical dark spots, either isolated or clustered, not elongated with irregular edges.
RT - Slag Inclusion Indication
On a radiograph, a slag inclusion appears as a dark, irregular, and often elongated indication within the weld metal, typically with random orientation.
- Dark indication (lower density than parent metal).
- Irregular shape, often elongated.
- Randomly oriented.
- Located within the weld bead.
Memory trick: Each defect has its own X-ray signature.