What types of flaws can ultrasonic testing detect?

Ultrasonic testing (UT) is specifically designed to detect internal discontinuities within a material, which includes a variety of flaws that can affect the integrity and performance of the tested component. The correct answer highlights that ultrasonic testing can effectively identify cracks, voids, inclusions, and other discontinuities.

The methodology behind UT involves the transmission of high-frequency sound waves into the material being tested. When these sound waves encounter a discontinuity, such as a crack or void, they will reflect back, indicating the presence of an internal flaw. This capability is particularly valuable for identifying defects that are not visible on the surface, which can lead to critical failures if left undetected.

The other options involve flaws that either lie on the surface or are better detected through other testing methods. For example, surface scratches might be identified through visual inspection or surface methods such as dye penetrant testing, while corrosion and oxidation can often be better evaluated with techniques such as magnetic particle testing or visual inspection. Temperature-induced deformities typically require different evaluation methods, such as thermal imaging or mechanical inspection, rather than ultrasonic testing. Thus, the focus of UT on internal flaws makes option B the most accurate representation of what this testing can detect.