Testing for Defects in Pulsed Magnetic Field Transmitted Through Metal

We present experimental dependences $$U(t)$$ of electric voltage on time $$t$$ picked up from an induction magnetic head (MH) moving relative to a magnetic carrier (MC) with the records of the magnetic fields due to a defect in an aluminum object. The contact access to the surface of a metal object above which there is a layer of air and a solid dielectric in an arbitrary proportion and with a total thickness of more than 5 mm is completely excluded. There is also no access to the rear side of the object, as it is a massive dielectric. An object with a magnetic field is exposed to a complex-shaped magnetic-field pulse with a duration from 1 to 200 $${{\mu s}}$$ . The studies were carried out in a field that has passed through metal. The raster images of hidden holes with diameters of 3 and 6 mm in 0.67 mm thick aluminum layers of samples composed of aluminum layers of various thickness separated by dielectric (air) layers were obtained. The thickness of metal layers in the samples was 1.96 and 2.96 mm. The measurements were carried out in hard-to-reach places of the samples. The algorithm of the developed method is compiled. The method makes it possible to significantly increase the sensitivity and accuracy of characterizing defects and to monitor areas of objects where testing by other methods is impossible.