The effect of microstructural changes on magnetic Barkhausen noise and magnetomechanical acoustic emission in Mn–Mo–Ni pressure vessel steel

Abstract

The effect of microstructural changes on magnetic Barkhausen noise (BN) and magnetomechanical acoustic emission (MAE) in Mn–Mo–Ni pressure-vessel steel with various microstructures was investigated. The BN and MAE signals were strongly influenced by the microstructural features which were characterized by transmission electron micrograph observation. BN energy and the measured area under the rectified signal envelope varied inversely with hardness, and changed with the microstructure. It indicates that they are closely related to the dislocation density and residual stress which act as a barrier to irreversible domain wall motion.