Influence of Magnetizing Conditions on Barkhausen Noise in Fe Soft Magnetic Materials after Thermo-Mechanical Treatment

Abstract

Low alloyed steels of low, medium, or high strength are frequently used for many applications in the automotive, civil (bridges), aerospace, and petrochemical industries. A variety of thermomechanical regimes, in which these steels can be produced, enable customization of their matrix with respect to their fatigue resistance, resistance against friction and impact wear, fracture toughness, corrosion resistance, etc. This study analyses the influence of magnetising conditions on Barkhausen noise and other extracted parameters. It was found that the increasing magnetising frequency makes Barkhausen noise weaker, especially in the high strength low alloyed steels, as a result of the decreasing magnetic field in a sample. For this reason, increasing fraction of domain walls is unpinned at the higher frequencies. Barkhausen noise for the high strength low alloyed steels at higher frequencies is remarkably attenuated. Moreover, the different behaviour with respect to direction of the sheet rolling and the transversal direction, can be found due to realignment of the domain walls. This study demonstrates that the position of Barkhausen noise envelopes and the number of Barkhausen noise pulses increase in a systematic manner at the lower magnetising frequencies. Those parameters can be employed for distinction of the low alloyed steels, investigated in this study. However, the increasing magnetising frequency makes attenuation of Barkhausen noise more remarkable for the low alloyed steels of the higher strength. Therefore, the effective value of Barkhausen noise, at the magnetising frequency 750 Hz, in the rolling direction exhibits the systematic descent along with the increasing yield strength. This parameter can be used for distinction of the low alloyed steels after their thermomechanical processing, as well.

Influence of Demagnetization and Microstructure Non-Homogeneity on Barkhausen Noise in the High-Strength Low-Alloyed Steel 1100 MC

“…On the one hand, the used sensor is capable of producing a stronger magnetic field altering in time [41], which might suppress the asymmetry in consecutive MBN bursts. However, the application of such magnetizing conditions can also result in a weaker sensitivity of MBN measurements to microstructure alterations and/or stress state, as reported in, e.g., [42][43][44]. Requirements considering sufficient demagnetization are associated with the magnetic field produced by the used sensor.…”

Influence of Demagnetisation on Barkhausen Noise in the High-Strength Low-Alloyed Steel 1100 MC

“…The MBN in TD are lower, and the heterogeneity of the MBN distribution is less pronounced. The remarkable heterogeneity of MBN (especially for RD) is due to the different degrees and the extent of decarburisation in the different regions [27]. Higher MBN is related to more developed decarburising, and vice versa.…”

“…However, applications of such magnetising conditions can also result in a weaker sensitivity of MBN measurements to microstructure alterations and/or stress state, as reported in e.g. [38][39][40].…”