Microstructure dependence of Barkhausen voltage pulse width in steel

Abstract

Barkhausen noise (BHN) is a voltage signal induced by a coil due to the discontinuous magnetization of ferromagnetic materials. The BHN voltage value is strongly correlated with the microstructure of such materials. In this paper, we propose a new model whereby the BHN voltage pulse width is proportional to the travel distance of the domain wall between pinning sites, and the constant of proportionality corresponds to the domain wall velocity. This correlation is examined using a model sample wherein cementite and copper precipitates as pinning sites for the domain wall were dispersed in ferrite. The test results show that the BHN voltage pulse width T and the precipitate spacing L had a proportional relationship, and that the constant of proportionality LT grew concomitant with increases in the excitation field. The change rate of LT with excitation field was 3.8 × 10 -4 A -1 m 2 sec -1, and corresponded well to the reported value that was the correlation coefficient between the domain wall velocity and the excitation field. This result demonstrates the validity of our model whereby the BHN voltage pulse is equal to the time required for the domain wall to jump over the pinning sites. © 2012 American Institute of Physics.