Detection and Classification of Defects

Abstract

The detection of defects by observing their ultrasonic echoes is usually quite simple and rapid. More difficult and much more time-consuming is the classification of defects according to their type, shape and size. This is fundamentally due to the basic handicap of ultrasonic testing in having a poor lateral resolution because of the relatively long wavelength used. Even when using the most complex imaging methods of Section 13 a precise defect image cannot be expected. Also because these methods have to be restricted in practice to relatively simple-shaped specimens, other means have to be used in the wider applications to establish a little more about a defect than only its geometrical position.