Magnetic Barkhausen noise measurements on magnetized pipeline steel

摘要

Magnetic Barkhausen Noise (MBN) is created by the irreversible motion of 180-degree domain walls. It is sensitive to residual and applied stress in ferromagnetic materials such as pipeline steel and has therefore been proposed as a viable non-destructive evaluation technique for monitoring the magnetic anisotropy and inhomogeneity, MBN occurs at the greatest rate of change in magnetization, essentially at B～0T. For MBN to complement standard NDE techniques such as magnetic flux leakage (MFL) which operates in the near magnetic saturation regime, we analysed MBN signals acquired from a heavily magnetized pipeline steel sample (B～1.6 T). A coercive field or pinning model developed for the MBN anisotropy data has proven to yield the magnetic easy axis of the sample prior to magnetization.