Discontinuity Interpretation and Evaluation Flashcards
7 cards from real NDT practice questions. Tap to flip, then mark Knew It or Still Learning — missed cards come back until you master them.
Read the first 7 Discontinuity Interpretation and Evaluation flashcards as text
A weld radiograph shows a dark, elongated indication with fuzzy edges running parallel to the weld axis. This is most likely:
Answer: Incomplete fusion
Incomplete fusion appears as an elongated dark line with fuzzy or diffuse edges parallel to the weld joint.
In ultrasonic testing, a discontinuity signal that appears at half the material thickness and disappears when the probe is angled slightly is most characteristic of:
Answer: Lamination
Laminations are planar discontinuities parallel to the plate surface that produce signals at mid-thickness and are highly angle-sensitive.
During magnetic particle testing, a tight linear indication is found perpendicular to the applied field. The inspector should:
Answer: Re-inspect with field perpendicular to the indication
An indication perpendicular to the field may be a false indication; rotating the field 90° confirms whether it is a true discontinuity.
A liquid penetrant indication that bleeds out rapidly and becomes large and diffuse most likely indicates:
Answer: A gross surface porosity or large opening
Rapid, diffuse bleed-out is characteristic of wide, open discontinuities such as gross porosity that hold large volumes of penetrant.
When evaluating a radiograph, a bright (white) round spot surrounded by a dark halo is most likely:
Answer: Tungsten inclusion
Tungsten inclusions appear as bright white dense spots because tungsten is more radiographically opaque than the surrounding weld metal.
A phased array ultrasonic S-scan image shows a curved, bright indication originating from the weld root. The most probable discontinuity is:
Answer: Lack of root penetration
Lack of root penetration produces a strong reflector at the root region visible on S-scan as a bright indication at the expected root depth.
In eddy current testing, a discontinuity signal whose phase angle is near 0° on the impedance plane most likely indicates:
Answer: Lift-off change
Lift-off signals appear near 0° phase on the impedance plane, which is why lift-off direction is established first to separate it from defect signals.