Investigating pipeline steel inhomogeneity with Magnetic Barkhausen Noise and Magnetic Flux Leakage

An understanding of pipeline steel characteristics under conditions of high stress and background magnetization is critical for interpretation of the Magnetic Flux Leakage signals obtained under similar conditions. The Barkhausen effect is due to abrupt and irreversible changes in the domain magnetization of a ferromagnetic material when it is subjected to a varying magnetic field. Magnetic Barkhausen Noise (MBN) is proposed as a viable NDE technique for the characterization of pipeline steel samples in conjunction with other widely used NDE methods. A quantity - 'MBN Energy' - is defined, which allows the detection of sample features such as pipeline welds, bulk magnetic easy axes and manufacturing stresses indirectly. This work examines the analysis of the MBN signal for the retrieval of information from samples under such extreme circumstances