Investigation of strain dependent magnetic Barkhausen noise in steel

Angular dependent magnetic Barkhausen noise (MBN) measurements were performed on three pipeline steel samples under uniaxial tensile stress up to 260 MPa. An expression for the angular dependent strain given by δL/L≈ΔL/L(1+ν)sin²θ, where θ is the angle of the strain component with respect to the maximum strain ΔL/L, was compared with the results. It was observed that the MBN signal was greater for the magnetic sweep field aligned along directions of greater tensile strain. Results were interpreted in terms of the relative increase of the active 180° domain wall population in the direction of the applied magnetic field and in the sense of increasing tensile strain