Electromagnetic Testing Eddy Current in Brief

Conductivity is sensitive to cracks and material in-homogeneities;
-Cracks
- Defects
-Voids
- Scattering of electrons
Magnetic permeability is much more sensitive to structural changes in
magnetic materials;
- Dislocations
- Residual stress
- Second phases
- Precipitates
Frequency selection will greatly affect eddy current response. Selection of
the proper frequency is the essential test factor under the control of the test
operator. The frequency selected affects not only the strength of the response
from flaws and the effective depth of penetration, but also the phase
relationship.
Charlie Chong/ Fion Zhang