Ultrasonic inspection (UT) is one of the most widely used methods of nondestructive inspection. Its primary application in the inspection of metals in the detection and characterization of internal flaws; it is also used to detect surface flaws, to define bond characteristics, to measure the thickness and extent of corrosion.
Beams of high frequency sound waves are introduced into materials for the detection of surface and subsurface flaws in the materials. The sound waves travel through the material with some attendant loss of energy (attenuation) and are reflected at interfaces.
The reflected beam is displayed and then analyzed to define the presence and location of flaws or discontinuities.
Cracks, laminations, shrinkage, cavities, bursts, flakes, pores, disbonds, and other discontinuities that produce reflective interfaces can be easily detected.
Inclusions and other inhomogeneity can also be detected by causing partial reflection or scattering of the ultrasonic waves or by producing some other detectable effect on the ultrasonic waves.