Nondestructive testing for metallic flaws using inductive coil sensor with circular typed single loop excitation coil

Abstract

AC magnetic field was used for the detection of flaws on surface of the conductive specimens. The nondestructive sensor probe was composed of the magnetic yoke coil as a sensing component and exciting single line coil. The excitation coil generated the AC magnetic fields with the frequency of around 27 kHz which were applied to the specimen with artificial flaws. The specimens were prepared with the various shape (slit and hole), size (minimum depth and width; 0.5 mm) of artificial flaws on each of material (Al Cu; nonmagnetic metal, Fe, FeC; magnetic metal), respectively. The signal for the positions and shapes of surface flaws on metallic specimens were detected with high sensitivity with signal to noise ratio of over 15 by the magnetic yoke typed search coil. The images of flaws were obtained by measured output signal, which results were good coincidence with real flaws. (C) 2007 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.