ORIENTATION EFFECTS OF ANISOTROPY, STRESS, EXCITATION, BIAS AND RESIDUAL FIELDS ON BARKHAUSEN NOISE GENERATION IN PIPELINE STEEL

Magnetic Barkhausen noise (MBN) measurements were made on a semicircular section of pipe applying the Barkhausen excitation field in different directions through 360 degrees. A DC bias field was then applied in the axial and circumferential directions and MBN measurements were made. A circumferential tensile stress of 129 MPa was then applied and MBN measurements were made with and without the DC bias field. The MBN data were analysed in the light of changes in the domain configuration due to the application of tension and/or the DC bias field. The relative orientations of preferred easy axis, Barkhausen excitation field, bias and residual fields and stress were all found to influence MBN generation. © 1990 IOP Publishing Ltd.