In ET, how are defects quantified?

In eddy current testing (ET), defects are quantified primarily by measuring variations in amplitude and phase shift of the eddy current signals. When an eddy current probe is used, it induces eddy currents into the conductive material being tested. The presence of defects, such as cracks or discontinuities, alters the flow of these currents.

These changes result in variations in the amplitude (strength) of the eddy current signal and can also lead to changes in the phase of the signal. The amplitude of the signal relates directly to the depth and size of the defect, while the phase shift can provide insight into the type and orientation of the defect. Thus, by analyzing both the amplitude and phase shift of the signals received, technicians can effectively quantify defects in the material.

Other methods mentioned, such as measuring temperature variations or analyzing signal frequency, do not provide direct and comprehensive evaluations of defects in the same way that amplitude and phase measurements do. Similarly, while assessing physical size and shape could be relevant in a broader sense, it does not specifically address the quantification of defects through eddy current signals in the context of the eddy current testing process.