t), where Hm - peak intensity, - cyclic frequency, t - time) for quasi-static approximation and at the sample demagnetization factor N = 0 is find from expression [1] B3m = 4/15
µoH2m where - Rayleigh's constant, µo - magnetic constant, equal410-7 H/m. At N 
0 (also in quasi-static approximation) B3m also depends on the initial magnetic permeability µin, N . The known [2] correlation 
and µin with densityof dislocations 
(namely, 
, where k and k1 - constants,dependent on parameters of a ferromagnet) allows to establish dependence B3m on.The occurrence of eddy currents under action of an exciting field in a controllable site of metal also influences over the character of dependence B3m on and µin. However, frequently the character of dependence B3m on any controllable parameter (for example, hardness after hardening) remains practically identical at magnetic reversal as by low-frequency (quasi-static) and so by rather high-frequency exciting field, and also as at magnetic reversal of a sample in the through- pass transducer, and at magnetic reversal of its local site with the help of the miniature superimposed transducer. Change of dislocations density at plastic deformation of metal, at hardening allows to carry out in this case nondestructive testing by measurements B3m, applying the miniature superimposed transducer. In particular, in this way the testing of plastic deformation intensity, surface hardened layer depth are carried out.
1. Bozorth R.M. Ferromagnetism. New York. 1951.
2. Kronmuller H. Z. angew. Physik. 1970, 30, 1: 9-13.
Abstract Source:
Book of Abstracts, 7th European Conference on Non-Destructive Testing, 26-29 May 1998, ISBN: 87-986898-0-00
Full-Text Source:
Proceedings of the 7th European Conference on Non-Destructive Testing, 26-29 May 1998, ISBN:
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