A Differential Fluxgate Probe for Metal Loss Assessment Due to Corrosion

Corrosion stands as a prevailing concern linked to steel structures, which, when it occurs, may result in metal loss, posing a potential threat to the integrity of the steel structure. To facilitate the detection of metal loss caused by corrosion, the utilization of magnetic flux leakage (MFL) and eddy current testing (ECT) proves to be advantageous. This study involves the development of a differential magnetic probe that integrates both methods. The probe comprises two fluxgate sensors and an excitation coil. Subsequently, A line scan measurement is performed on a 6-mm mild steel sample, which consists defects resulting from metal loss. The line scan measurement of the MFL signals allows for the identification of both the presence and depth of the defects. Conversely, the ECT signals can only identify the presence of defects, but they are limited to higher frequencies. Notably, a percentage difference of 43.88% in the real component and 30.52% in the imaginary component was observed between the 15 and 25 ml volumes of electrolyte.