ET eddy-current method

The method of eddy-currents is the most used method of electromagnetic testing of electrically conductive materials and this method belongs to the so called surface methods. The method of eddy-currents reveals easily and conclusively very fine surface cracks in material, various corrosive attacks, mechanical deformations, material mix-up and defects right under the surface. The method is based on the principle of generation of eddy-current on the surface of conductive material; this current can detect the defect on the material surface by means of a sensing head.


The eddy-currents are widely used in nuclear, power, petrochemical, automotive, aircraft and engineering industry. The most frequent use of eddy-currents is the inspection of non-ferromagnetic and ferromagnetic tubes in production or tubes already installed in heat exchangers operated in power or petrochemical industry. This method has further very good results during inspection of rotor blades in steam or internal combustion turbines. The method is used in automotive industry for testing of various components, the occurrence of fine cracks is tested or material properties are detected such as hardness of full hardened layer or material mix-up.


In order to have the right adjustment of the devices, in this method it is necessary to use so called reference standards with artificial defects with the same material as the tested piece.