Fyzikální ústav Akademie věd ČR

The developed technique is based on the idea of optimization of earlier known magnetic hysteresis methods. Instead of collecting the usable information from measurement of the classical major hysteresis loop and keeping under surveillance dependence of its traditional parameters (coercive force, remanence, and saturation magnetization) on structural variations, MAT gets its test parameters from the complex set of minor hysteresis loops. Then, an original software package picks up from the measured data volume just those parameters, which are most suitable for characterizing the given investigated material and best adapted for manifesting its actual structural modifications. The optimum parameters, picked up in this way, are substantially (several times) more sensitive than the classical ones. Besides, as a rule, the optimum parameters originate from minor loops, i.e. they are measured at field values substantially lower than those needed for measurement of the major, i.e. the saturated hysteresis loop. The prospect of testing structural modifications of construction materials (e.g. in dependence on industrial wear and tear of the constructions) at low magnetizing fields and with high sensitivity, are the main advantages of MAT. Typical examples of successful application of MAT are for instance structural modifications due to mechanical stress, plastic deformation, cyclic fatigue, surface decarburization or radiation embrittlement of steel [1-3].
[1] I.Tomáš, "Non-Destructive Magnetic Adaptive Testing of Ferromagnetic Materials“, J. Mag. Mag. Mat. 268/1-2 (2004) 178-185 (doi:10.1016/S0304-8853(03)00496-7)
[2] I.Tomáš, G.Vértesy, J.Kadlecová, “Influence of rate of change of magnetization processes on sensitivity of Magnetic Adaptive Testing”, J.Magn.Magn.Mater. 321 (2009) 1019-1024 (doi:10.1016/j.jmmm.2008.10.003)
[3] I.Tomáš, G.Vértesy, S.Kobayashi, J.Kadlecová, O.Stupakov, “Low Carbon Steel Samples Deformed by Cold Rolling – Analysis of the Magnetic Adaptive Testing” J. Magn. Magn. Mater. 321 (2009) 2670–2676 (doi:10.1016/j.jmmm.2009.03.061)