Detection of Small Flaws using the Potential Drop Technique

This work presents a non-intrusive method to detect the presence and obtain information about small flaws, caused by internal corrosion in a specimen or samples of carbon steel. The Potential Drop technique provides an electric potential gradient map, which can give information about the presence and the geometry of minor defects in the material structure. The detection of small flaws, such as cracks caused by hydrogen corrosion, was achieved using the geometry analysis of surface electric potential and current density curves. Acting similarly to an electric lens, the disturbance in the lines of current density and surface potential caused by small flaws, can provide an apparent enlargement of the dimensions of a small flaw. Observing the geometric expansion of the electrical disturbance generated by the flaw, caused by the curvature of the field lines, small flaws can be more easily detected. Diminute cracks inside a small steel specimen can be difficult to detect using traditional non-destructive testing techniques, such as ultrasound and tomography, but, the presented technique can be used as a simpler and cheaper alternative.