Ultrasonic Testing (UT)
Definition - What does Ultrasonic Testing (UT) mean?
Ultrasonic testing is a form of nondestructive testing. Ultrasonic testing uses special equipment to send high frequency sound waves to penetrate a material's thickness. Other special equipment is then used to receive these sound waves. Determinations about material condition and discontinuities can be made based on how the high frequency sound waves are returned to the recording equipment.
Ultrasonic testing can be used to detect a variety of discontinuities. Material thickness checks can be done to determine the extent of corrosion a component has undergone. This is especially useful when only one side of the component is accessible. Ultrasonic testing can also be used to detect flaws that radiographic inspection may not be able to detect. Discontinuities such as laminations, when observed perpendicular to the plane of the lamination, are not easily detectable by X-ray; ultrasonic testing is better suited for detecting this flaw.
Corrosionpedia explains Ultrasonic Testing (UT)
Nearly all forms of ultrasonic testing have the same few basic components. The transducer in an ultrasonic testing system is the origin point of the high frequency waves. It projects these waves through the material. The energy that is bounced back by geometric irregularities, such as discontinuities or edges, is picked up by the transducer. Once received by the transducer, it is interpreted by a computer that then graphs and displays these signals. A trained operator then reads these graphs and displays.
Ultrasonic testing uses high frequency sound waves to penetrate materials. These sound waves typically have a wavelength of 0.5 MHz and 25 MHz. When shorter wavelengths are used, smaller discontinuities and defects can be detected. Longer wavelengths lead to lower detection sensitivity. The proper wavelength depends on the material type, material crystalline structure and probable defect shapes and sizes.