Study of acceptance criteria problems in metal magnetic memory method of NDT

The method of metal magnetic memory (MMM) was developed for diagnosing of ferromagnetic materials. It based an scientific principle, that ferromagnetic materials are subjected to elastic-plastic deformation in the Earth´s magnetic field then spontaneous magnetic-flux-leakage (SMFL) signals are formed in the zones of steady strips of dislocations sliding , stipulated by combined action of a working load and a magnetic field of the Earth. But, it is not published the acceptance criteria standard for this method. Therefore the acceptance criteria problem should be solved. This paper describes the some theoretical research and experimental results obtained from our experiment for determination of magnetic index in for steels St-3, St-20 and 12X18H10T (Gost designation).