Ultrasonic testing (UT) is a family of non-destructive testing techniques based on the propagation of ultrasonic waves in material tested through various probes.
In most common UT applications, very short ultrasonic pulse-waves with center frequencies ranging from 0.1-15 MHz, and occasionally up to 50 MHz, are transmitted into materials to detect internal flaws or to characterize materials. A couplant is used to increase the efficiency of the process by reducing the losses in the ultrasonic wave energy due to separation between the surfaces.
There are two methods of receiving the ultrasound waveform: reflection and attenuation.
Reflection (or pulse-echo) mode:
The transducer performs both the sending and the receiving of the pulsed waves as the "sound" is reflected back to the device. Reflected ultrasound comes from an interface, such as the back wall of the object or from an imperfection within the object. The diagnostic machine displays these results in the form of a signal with amplitude representing the intensity of the reflection and the distance, representing the arrival time of the reflection.
Attenuation (or through-transmission) mode:
A transmitter sends ultrasound through one surface, and a separate receiver detects the amount that has reached it on another surface after traveling through the medium. Imperfections or other conditions in the space between the transmitter and receiver reduce the amount of sound transmitted, thus revealing their presence.
Applications of UT
UT is often performed on steel and other metals and alloys, though it can also be used on concrete, wood and composites, albeit with less resolution. It is used in the following industries:
- Steel and aluminium construction
- Other transportation sectors
We perform the test in accordance to ASTM E2375: Standard Practice for Ultrasonic Testing of Wrought Products