Eddy Current Testing (ET) is used to assess the integrity of ferritic, austenitic, and non-ferrous alloys. It is a non-destructive method based on the principle of electromagnetic induction, employed to detect surface and near-surface discontinuities in electrically conductive materials. This technique enables the identification of defects such as cracks, laps, folds, flakes, inclusions, both on the surface and just beneath it.
The inspection involves introducing an alternating magnetic field into the tested material. This induces eddy currents in the material, which are disrupted in the presence of discontinuities. These disturbances affect the impedance of the probe, which is recorded and analyzed by the ET flaw detector. The depth of penetration depends on material properties such as electrical conductivity and magnetic permeability.
ET is applied both during manufacturing and in-service inspection. The method is used to inspect: welds and heat-affected zones in welded structures, pipes, rods, wires, and other rolled products, as well as components of industrial installations, pressure vessels, and boilers. Eddy Current Testing is especially useful when fast, non-invasive inspection of large volumes of components is required, for example, in serial production. The technique can be applied to both coated and uncoated surfaces.