Scattering
As the ultrasound wave travels through the part, its energy is gradually scattered by physical obstacles.
- An ultrasound wave is emitted
- As it travels through the material, part of its energy is deflected by grains. The result is a lower amplitude wave at the bottom of the part
Materials with bigger grain structure such as austenitic materials are typically more difficult to penetrate with ultrasound because the scattering effect is stronger in these materials.