Crack detection

Inspection of a workpiece for presence of cracks.
The most common methods for this purpose are ultrasonic testing, magnetic particle method, and dye-penetrant test. These methods are generally used for location and/or detection of cracks, precise definition of crack propagation or expansion is not possible.

Also the acoustic resonance analysis, which is also referred to as sound testing, is a nondestructive testing method, which enables a wide range of workpieces to be tested rapidly and inexpensively. They are the “language” of the workpiece. The dynamic strength of the component is evaluated, because any cracks, defects or other material structure deviations, which may be present, cause a change in the resonance spectrum.

Additional references:
Hardening crack
Hot crack
Cold crack
Warm crack