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In the present work a model for the correlation between magnetocrystalline anisotropy energy and Barkhausen noise is proposed. The link between the magnetocrystalline anisotropy energy and the magnetic Barkhausen noise is due to the influence of the crystallographic texture on the domain nucleation process which produces the Barkhausen signal in the branch from saturation to remanence. The statistical distributions of magnetic free poles and local fields of nucleation and subsequent growth of reversed domains were obtained for a large number of grain boundaries and used to estimate the number and size of Barkhausen events at each angular position from 0 to 360° in ten degree-steps. The good agreement observed between the modeled magnetocrystalline energy and the prediction of this energy made from X-ray texture and Barkhausen noise measurements corroborates the validity of the proposed model.

This work analyzes the differences between the magnetic Barkhausen noise corresponding to the initial magnetization curve and Barkhausen noise corresponding to one branch of the hysteresis loop in API-5L steel. The outcomes show that the Barkhausen noise signal corresponding to the initial magnetization curve and that corresponding to the hysteresis are significantly different. This difference is due to the presence of different processes of the domain wall dynamics in both phenomena. To study the processes present in magnetization dynamics for an applied field of H > 0, research into the angular dependence of a Barkhausen signal using applied field bands has revealed that a Barkhausen signal corresponding to the initial magnetization curve is more suitable than a Barkhausen signal corresponding to the hysteresis loop.

The present work analyzes the influence of electric conductivity on the Magnetic Barkhausen Noise (MBN) signal using a microscopic model which includes the influence of eddy currents. This model is also implemented to explain the dependence of MBN on the frequency of the applied magnetic field. The results presented in this work allow analyzing the influence of eddy currents on MBN signals for different values of the material's electric conductivity and for different frequencies of applied magnetic field. Additionally, the outcomes of this research can be used as a reference to differentiate the influence of eddy currents from that of second phase particles in the MBN signal, which has been reported in previous works.

This work studies the influence of the maximum applied magnetic field on the angular dependence of the energy of the Magnetic Barkhausen Noise signal in three different API5L pipeline steels. The results show that the shape of the angular dependence of the Magnetic Barkhausen Noise energy changes with the increase of the amplitude of the applied magnetic field. This phenomenon is a consequence of the presence of unlike magnetization processes at different magnitudes of the applied magnetic field. The outcomes reveal the importance of controlling the value of the maximum applied field as parameter for the improvement of the MBN angular dependence measurements.

A method for determination of the magnetic easy axis of the Roll Magnetic Anisotropy in API-5L steels is proposed. The method is based on the fact that the angular dependence of the energy corresponding to the main peak of the Magnetic Barkhausen signal presents uniaxial anisotropy with its easy axis parallel to the rolling direction, independently of the angular dependence of the magnetocrystalline energy in the materials. The proposal is also justified based on the analysis of the influence of microstructural changes, produced by hot-rolling on the domain wall dynamics.

A microscopic model of magnetic Barkhausen noise (MBN) in carbon steel is proposed. The model uses the quasi-static magnetic formulation of Maxwell equations for electromagnetic fields combined with a microscopic model of the magnetic Barkhausen noise, and its equations are solved by means of finite difference formulation. The simulated MBN signal obtained presents high similarities to the measured MBN signal. Using this model, the influences of the uniformity and waveform profile of the excitation magnetic field on the envelope of the MBN signal were studied. The results show that the lack of uniformity of the excitation magnetic field increases the amplitude of the MBN envelope at the right of its main peak, and the waveform profile influences the shape of the MBN envelope. The proposed model can be used as a tool for studying the influence of several excitation parameters on the Barkhausen Noise in order to improve this technique.

The magnetic Barkhausen noise (MBN) is a phenomenon sensitive to several kinds of magnetic material microstructure changes, as well as to variations in material plastic deformation and stress. This fact stimulates the development of MBN-based non-destructive testing (NDT) techniques for analyzing magnetic materials, being the proposition of such a method, the main objective of the present study. The behavior of the MBN signal envelope, under simultaneous variations of carbon content and plastic deformation, is explained by the domain wall dynamics. Additionally, a non-destructive parameter for the characterization of each of these factors is proposed and validated through the experimental results.

This study presents a model of the microstructural defect influence on the magnetic Barkhausen noise in plain steels. The comparison of the theoretical and experimental results reveals an excellent agreement between them. We show that both model and experimental approach can be very useful, particularly, for the carbon content characterization in commercial steels.