PROCEDE DE DETERMINATION DES HETEROGENEITES DANS LES MATERIAUX MAGNETIQUES ET DISPOSITIF PAR SA MISE EN OEUVRE

L'INVENTION CONCERNE LES TECHNIQUES UTILISANT LES ULTRA-SONS.LE PROCEDE FAISANT L'OBJET DE L'INVENTION EST DU TYPE CONSISTANT A PLACER LE MATERIAU A ETUDIER 2 DANS UN CHAMP MAGNETIQUE, ET A FAIRE AGIR DES VIBRATIONS SUR LA SURFACE D'UN MILIEU MAGNETOSTRICTIF DISPOSE A PROXIMITE DE LA ZONE DES HETEROGENEITES DU MATERIAU.L'INVENTION S'APPLIQUE NOTAMMENT AU CONTROLE NON DESTRUCTIF DE TOLES, BANDES, TUBES, BARRES ET D'AUTRES ARTICLES SUSCEPTIBLES D'AIMANTATION, DIRECTEMENT DANS LES CHAINES DE PRODUCTION. The method for detecting non-uniformities of magnetic materials resides in the use of the direct and inverse electromagnetic-acoustic conversion, effected in the zone of magnetic non-uniformities of magnetized articles. The method is characterized by effecting said conversion in an intermediate layer located in the vicinity of the material being inspected. As the intermediate layer, materials with great values of dynamic magnetostrictive constants are used. The use of the intermediate layer of a predetermined configuration enables estimation of the non-uniformity value not only singularly by the amplitude of the established elastic vibrations, but also by the number of recurrent pulses whose pulse-height distribution is conditioned by the damping factor of the intermediate layer. In the given device, as distinct from the conventional noise-suppressing devices, operating on the principle of decoding the coded signals, the parameters of the code are defined by the material and structure of the intermediate layer.