What happens to the signal-to-noise ratio when the saturation of ferromagnetic material is reached during eddy current testing?

When the saturation point of a ferromagnetic material is reached during eddy current testing, the signal-to-noise ratio typically shows no significant change. This is because, under normal conditions, increasing the magnetic permeability of the material enhances the eddy currents at low frequencies. However, once saturation is achieved, further increases in magnetic field strength do not contribute to higher eddy current levels, as the material can no longer respond effectively to the magnetic field. Consequently, the signal generated remains stable, and any noise that is present does not significantly alter the signal-to-noise ratio. This is a crucial aspect in interpreting results during eddy current testing, as it indicates that the material's response remains consistent, allowing for reliable assessments of material properties and potential defects.