Effect of Microstructure Changes on Barkhausen Noise Properties and Hysteresis Loop in Cold Rolled Low Carbon Steel

Low carbon steel specimens cold rolled at ratios of 0-40% have been examined comprehensively by means of magnetic Barkhausen noise (MBN) method and a physical parameter obtained from a hysteresis loop, and their microstructures were studied by a transmission electron microscope. The behaviors of MBN and coercive force with reduction ratio were discussed in relation to microstructure changes. The MBN energy rises rapidly with cold rolling below 10% reduction, and saturates at higher reduction ratio. The peak in averaged rms voltage exhibited the same behavior as that of the MBN energy, whereas the coercive force and the magnetizing current when the averaged rms showed a peak increased monotonically with increasing reduction ratio. These phenomena are attributed to the combined effects of cell texture and dislocation density.