ULTRASONIC TESTING

Principle of UST
ULTRASONIC INSPECTION is a nondestructive method in which beams of high-frequency sound waves are introduced into the material to be inspected for detection of flaws.
The sound waves travel through the material with some attendant loss of energy (attenuation) and are reflected at interfaces.
The reflected beam is displayed and then analyzed to define the presence and location of flaws or discontinuities.
FLAW CHARACTERISATION TECHNIQUE METHODS:
Most widely used flaw sizing method for flaws….
6DB drop method.
20DB drop method.
6 DB DROP METHOD
For larger flaws
When flaw size is comparable or larger than beam width
The echo is adjusted to the full screen height by one half.
FOR PLANAR FLAW
For planar flaws with orientation perfectly normal to the plane of transducer, the method correctly locates the edge of the flaw and planar shape could be traced.
LIMITATIONS:
Unreliable for the flaws of irregular shape and varying roughness