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Materials Characterization Terms of Use
Ultrasonic Testing
Materials Characterization us used to differentiate between material microstructure or materials properties. For example, eddy current is used to differentiate between materials with difference in conductivities or permeability. Ultrasonic scattering depends on grain size and therefore can be used to differentiate the same material but with two different grain sizes.

The Rayleigh scattering zone is defined as the region where d<λ, d-grain size, λ is the wavelength. In this zone, attenuation is proportional to d3f4

Backscattering measurements are taken in the range of 0.03< d/λ <0.3

The figures below show ultrasonic attenuation being used to differentiate between cast and forged flanges. Both flanges are made of the same material.

 

FORGED FLANGE - Low Attenuation

 
Cast Flange - High Attenuation

 
Note the variations in grain size. These affect ultrasonic attenuation

 

  
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