NDT Ultrasonic Testing Principles 4

Question 1

What is the primary advantage of phased array ultrasonic testing (PAUT) over conventional single-element UT?

Accepted Answer

It electronically steers and focuses the beam without moving the probe

Answer

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.

Question 2

In angle-beam shear wave testing of welds, the 45°, 60°, and 70° refracted angles refer to the angle of:

Accepted Answer

The refracted shear wave in the test material relative to the normal

Answer

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.

Question 3

What phenomenon occurs when the grain size of a metal approaches the wavelength of the ultrasonic wave used?

Accepted Answer

Significant scattering occurs, increasing background noise and limiting penetration

Answer

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.

Question 4

The V1 (IIW) calibration block is primarily used to:

Accepted Answer

Calibrate the time base (range) and sensitivity of angle-beam and straight-beam probes

Answer

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.

Question 5

Time-of-flight diffraction (TOFD) technique measures:

Accepted Answer

The travel time of diffracted waves from flaw tips to calculate flaw height

Answer

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.

NDT - Non-Destructive Testing Practice Test

NDT - Non-Destructive Testing Practice Test

NDT Ultrasonic Testing Principles 4