Principal component analysis of magnetic steel eddy current testing data

In this study, multi-frequency eddy current testing of carbon steel St3 specimens with dielectric coatings is conducted. Inhomogeneity of steel structure of the specimens with the same chemical composition plays a crucial part during the testing. Plotted experimental hodographs allow investigation of the combined influence of magnetic permeability, electrical conductivity, and thickness of the dielectric coating. The principal component analysis is used to improve testing parameter identification and differentiate the influencing factors. The applied analysis demonstrates non-overlapping clusters of points that represent the eddy current testing data of different steel specimens. The proposed approach can be used for the non-destructive eddy current testing of magnetic steel products with protective-strengthening coatings.