Ultrasonic Testing
Ultrasonic Testing in chennai is an NDT method applied to detect internal flaws in materials, components and structures. Ultrasonic is sound beyond the human audible range that is 20 to 20 kHz. Ultrasonic inspections use frequencies of above 0. 5 MHz up to 25 MHz to test metals, ceramics, glass, composite and other engineering materials.
Ultrasonic testing is commonly used for inspecting castings, rolled bars, plates, forgings, thin sheets, extruded components, drawn components, welds and to measure reduction in thickness of pipes, vessels and other components
In ultrasonic testing, an ultrasound transducer connected to a diagnostic machine is passed over the object being inspected. The transducer is typically separated from the test object by a couplant (such as oil) or by water, as in immersion testing. However, when ultrasonic testing is conducted with an Electromagnetic Acoustic Transducer (EMAT) the use of couplant is not required.
There are two methods of receiving the ultrasound waveform: reflection and attenuation. In 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 an amplitude representing the intensity of the reflection and the distance, representing the arrival time of the reflection. In 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. Using the couplant increases the efficiency of the process by reducing the losses in the ultrasonic wave energy due to separation between the surfaces.
