Ultrasonic non-destructive testing technique for flaw detection is based on propagation and reflection of high-frequency (0.5 to 24 MHz) UT waves in a test object (steel, plastic, composites, rubber, etc.), with their further processing and visualizing on a special-purpose NDT instrument (flaw detector).
This method is used to search for material defects (pores, hairlines, inclusions, inhomogeneities, etc.) and to control workmanship quality like welding, soldering, etc. Ultrasound examination is a mandatory procedure for manufacturing and operation of numerous critical parts, such as aircraft motor parts, main pipelines or rails.
Basic UT techniques are as follows: