What is Ultrasonic Testing?
Ultrasonic testing (UT) is a form of non-destructive testing (NDT) that is commonly used to detect flaws (inclusions) that may exist in material which are not visible to the naked eye. UT testing is accomplished through the use of systems that generate high frequency sound waves (between .5 – 15Mhz), and incorporate a pulser/receiver, a series of transducers, and a display device. The pulser/receiver provides high frequency energy to the transducer (s). In turn, the transducer generates high frequency/ultrasonic energy in the form of sound waves. The sound waves propagate through the material, and are reflected back to the transducer. As these sound waves propagate through a given material under evaluation, the time in which the reflected sound wave comes back to the transducer is monitored by the receiver and compared to a standard. In the event there is a discontinuity in the wave path (caused by a crack) part of the sound wave will be reflected back from the inclusion surface faster than the reflection from the back surface of the material. The transducer will then generate an electrical signal that can be displayed for evaluation, and can be compared to the standard to determine if the flaw is in excess of acceptable limits. Figure 1 provides a simplistic overview of the process.
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