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

The effect of microstructural changes on magnetic Barkhausen noise (BN) and magnetomechanical acoustic emission (MAE) in Mn-Mo-Ni pressure-vessel stee l with various microstructures was investigated. The BN and MAE signals wer e strongly influenced by the microstructural features which were characteri zed by transmission electron micrograph observation. BN energy and the meas ured area under the rectified signal envelope varied inversely with hardnes s, and changed with the microstructure. It indicates that they are closely related to the dislocation density and residual stress which act as a barri er to irreversible domain wall motion. (C) 2000 American Institute of Physi cs. [S0021-8979(00)40008-3].