Ultrasonic Testing Principles 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 Ultrasonic Testing Principles flashcards as text
What is the primary advantage of phased array ultrasonic testing (PAUT) over conventional single-element UT?
Answer: It electronically steers and focuses the beam without moving the probe
PAUT uses multiple elements with time-delayed firing sequences to electronically steer, focus, and sweep the beam, allowing volumetric inspection from a single probe position.
In angle-beam shear wave testing of welds, the 45°, 60°, and 70° refracted angles refer to the angle of:
Answer: The refracted shear wave in the test material relative to the normal
In angle-beam testing, the quoted angle is the refracted shear wave angle measured from the normal (perpendicular) to the test piece surface, not the wedge or incident angle.
What phenomenon occurs when the grain size of a metal approaches the wavelength of the ultrasonic wave used?
Answer: Significant scattering occurs, increasing background noise and limiting penetration
When grain size approaches the wavelength, scattering from grain boundaries generates high background 'grass' noise and attenuates the beam, reducing the signal-to-noise ratio.
The V1 (IIW) calibration block is primarily used to:
Answer: Calibrate the time base (range) and sensitivity of angle-beam and straight-beam probes
The IIW block provides reference features (25mm radius, 50mm radius, 1.5mm side-drilled hole) used to set instrument sweep range and sensitivity for both contact and angle-beam techniques.
Time-of-flight diffraction (TOFD) technique measures:
Answer: The travel time of diffracted waves from flaw tips to calculate flaw height
TOFD uses diffraction signals from flaw tips; by measuring the time difference between tip diffraction arrivals and comparing to the lateral wave, accurate flaw height sizing is achieved.
Which factor does NOT directly affect ultrasonic wave attenuation in a material?
Answer: The color or surface finish of the part
Attenuation is caused by absorption and scattering, which depend on material microstructure, grain size, and frequency; surface color or paint finish does not affect internal wave attenuation.
In the through-transmission ultrasonic technique, what indicates the presence of a defect?
Answer: A decrease or total loss of the transmitted signal amplitude
In through-transmission, one transducer sends and another receives; a flaw blocks or scatters the beam, causing a reduction in received signal amplitude compared to the defect-free baseline.