The study of a racetrack-shaped defect in ferromagnetic steel by magnetic Barkhausen noise and flux leakage measurements

Abstract Magnetic Barkhausen noise (MBN) and magnetic flux leakage (MFL) measurements are useful magnetic nondestructive techniques used for various applications. MBN measurements have been used here to study stress distributions around a racetrack-shaped defect made in the wall of a steel pipe. The study shows a stress concentration factor of ∼3 for a racetrack-shaped defect with 50% wall penetration. MFL signals from the same defect have also been studied under various circumferential hoop stresses. It is observed that the external stress can change the MFL signal by more than 40% and the effect of stress is maximum when the pipe wall flux density is ∼1.2 T.