On the correlation between magnetoacoustic emission and magnetostriction dependence on the applied magnetic field

• Correlation between magnetoacoustic emission and magnetostriction is investigated.
• Both MAE and elongation rate are dependent on the non-180° domain walls movement.
• Heat treatment affects both phenomena in a similar way.
• For plastic deformation, such a correlation is lost.
• The correlation is present only if there is no strong change of the microstructure.

The correlation between magnetoacoustic emission signal envelopes and magnetostriction curves is investigated. Two sets of samples are being considered: tempered martensitic steel and plastically deformed ferritic steel. It is shown that even though some general relations may be observed, as was demonstrated in the literature, the correlation is not always present. One may not expect to change both quantities in the same way if a serious modification of microstructure takes place, as for instance in the case of plastically deformed samples for which the dislocation cell structure is formed once a certain level (1.5–2%) of deformation is reached. Being so, any relation not taking into account statistical properties of domain structure and pinning sites distribution may not yield a general solution of the problem.