Study on the theory of metal magnetic memory nondestructive testing technology

Metal magnetic memory technology is a new NDT method first introduced by Russian researchers. The purpose of metal magnetic memory testing was introduced. Compared with the traditional testing method, the characteristics were presented. On the basis of ferromagnetic theorem, the principle of the metal magnetic memory phenomenon of ferromagnetic structures engendered under the action of magneto-elasticity and magneto-mechanical effect has been investigated. Described was the electric circuit and principle of EMS-2000 portable metal magnetic memory diagnostic equipment for the early damages of parts which was developed on the basis of magnetic memory effect. By setting up the relational model of the stress field around cracks and variation of magnetic flux, the rules of the variation of magnetic flux were given as the theoretical basis and criterion for detecting cracks using metal magnetic memory technique. Finally, the objectives and the potential applications of metal magnetic memory testing technology were expected.