The Ultrasonic Examination (UT)
The ultrasonic examination employs mechanical vibrations in the megahertz-range. Other than air metals conduct this sound very well. For detection of discontinuities, the ultrasonic sound is lead through samples to be examined. If the sound beam hits fissures, it is reflected, deviated or absorbed. Mostly the pulse-echo-method is used. The echo of the reflected, deviated or absorbed sound beam is re-transferred into an electric signal by the ultrasonic probe that enables the examiner to detect, localise and evaluate internal discontinuities.
The ultrasonic examination is applied for thickness-measurements, weld-examination, the examination of spot-welds and shafts. Compared to radiography the ultrasonic examination is able to detect planar defects very well. Further advantages are both a much higher test speed and the need of only one single accessible surface.