Comparison of the magnetic barkhausen noise for low carbon steel in deformed and annealed conditions

The magnetic Barkhausen noise (MBN) in low carbon steel (0.034%C) was examined for two situations: after deformation and after recrystalization. The steel sheets previously received 50% of cold rolling and were heat treated for time periods between 15 to 540 min, originating different grain sizes. It was found that the maximum amplitude of MBN decreases with annealing time. Electron back scattered diffraction (EBSD) shows that significant grain fragmentation occurred due to plastic deformation. The results are discussed with help of the Two Gaussian model for the MBN envelope. The major contribution for MBN in the deformed sample was elimination of 90° closure domains. Displacement of 180° domain walls was limited in the deformed sample, due to the grain fragmentation.