## 3 Results of Experiments and Their Discussion
### MBN Measurements  
Angular dependence of MBN illustrated in Figure 8 depicts the magnetic anisotropy when the RD is the easy axis of magnetisation, whereas the TD is the hard one in the elastic region of straining (this anisotropy corresponds to that after hot-rolling before the uniaxial tensile test). Such character of magnetic anisotropy can be found for \(\varepsilon=2.5\%\). On the other hand, the \(10\%\) plastic straining is linked with the near isotropic state followed by the marked predomination of MBN in the TD at the higher strains. Figure 8 also illustrates that the intensity of magnetic anisotropy grows with \(\varepsilon\) (check MBN ratios between RD and transverse direction (TD) in [12]). Such behaviour is due to grain elongation when the marked crystallographic texture in TD becomes developed at higher strains, as Figure 2 demonstrates. Plastic straining reorganises the DWs' alignment into the TD direction at the expense of the RD, and especially the direction (001) as the magneto-crystalline easy direction in the _bcc_ lattice [2; 3; 29] takes the prevailing  
Figure 8: Angular dependence of magnetic Barkhausen noise (MBN) as a function of \(\varepsilon\). (**a**) \(\varepsilon=2.5\div 15\%\), (**b**) \(\varepsilon=20\div 40\%\); \(0^{\circ}\) corresponds to the rolling direction (RD). Figure 7: (**a**) Length fraction evolution of different boundary types as a function of \(\varepsilon\) and (**b**) normalised distribution of misorientation in the range of \(0\)–\(5^{\circ}\). role. However, Figure 8 demonstrates that MBN in the RD, as well as the TD direction, decreases along with \(\varepsilon\) due to the increasing dislocation density, expressed in terms of the crystallite size \(t\), as the opposition against DWs motion. Increasing dislocation density which increases the pinning strength of the matrix [4,5,8], expressed in terms of \(PP\) (as Figure 9 depicts), should also be considered as well as the superimposing reduction of the free path of DWs in motion. Decrease of MBN in the TD is slowed down since the increasing dislocation density and corresponding magnetic hardness is compensated by the aforementioned alignment of DWs into the TD. The evolution of MBN corresponds with the evolution of \(PP\) as the quantity correlated with the magnetic hardness of the body and therefore, the opposition of the matrix against DWs motion [4,30,31]. Figure 9 depicts that the higher MBN can be linked with lower \(PP\), and vice versa. A more developed \(\varepsilon\) produces a higher \(PP\) in the RD as compared with the TD and grows continuously with \(\varepsilon\). Figure 10 illustrates the conventional symmetric MBN bursts for \(\varepsilon=2.5\%\) when the shape, position in magnetising current, and the magnitude of the consecutive pulses are very similar (more or less the same)--no matter the ascending (referred to as positive) or descending (negative) phase of the magnetising current (two consecutive bursts represent one magnetising cycle through the hysteresis loop). However, Figure 11 shows the marked asymmetry in the shape as well as the magnitude of MBN pulses for \(\varepsilon=15\%\) in RD and magnetising voltage 5V. The different magnitudes of MBN pulses result in the different rms values of the MBN signal in the RD at lower \(\varepsilon\), as Figure 12a shows (the errors bars in this figure indicate the difference between two consecutive bursts). Figure 12b shows the pure difference between the rms value of positive and negative bursts. It can be clearly seen that the asymmetry in MBN (rms) vanishes at higher \(\varepsilon\) as well as along with the increasing magnetising angle. The TD direction exhibits nearly zero asymmetry, and this effect dominates in the RD. Much pronounced asymmetry in MBN can be found with respect to \(PP\), as Figures 13 and 14 illustrate. The height and position of the MBN envelopes is nearly the same for \(\varepsilon=2.5\%\), whereas the positive envelope for \(\varepsilon=15\%\) is shifted to the markedly higher magnetic field, as opposed to the negative one.