The in situ measurement of the effect of plastic deformation on the magnetic properties of steel - Part I - Hysteresis loops and magnetostriction

We report measurements of the bulk magnetic properties of pearlitic steels recorded in-situ during plastic deformation. Hysteresis loops were initially found to become squarer but became less so as the stress increased. Magnetostrictive measurements revealed that the tow field region showed zero magnetostriction. while the change to magnetisation vector rotations was shown to take place at lower magnetisation values with increasing tension. The coercive field remained constant or decreased with increasing stress at lower values of tension, but higher stress levels produced an increase attributed to new pinning sites generated by the plastic deformation process, This increase: proportional to the square of the stress, was seen to initiate before yield, rather than at the yield point. Remnant magnetisation was found to increase at lower tension levels, but higher stress levels produced a decrease in value that was attributed to stress induced changes in magnetic anisotropy. The high held magnetisation decreased monotonically with stress in both the pre-yield and plastically deformed regions. (C) 1998 Elsevier Science B.V. All rights reserved.