Uniaxial stress and wave mode dependence of magnetoacoustic responses in iron-base alloys

A detailed investigation was performed on magnetoacoustic responses of compressional waves and shear waves, with two different orientations of polarization, propagating in a low carbon, high yield strength steel specimen at various uniaxial stress levels. The experimental technique was to measure the fractional frequency shift of phase-locked acoustic waves as a function of net magnetic induction, Δf(B)/f. For the present study, the orientation of wave vector was fixed perpendicular to the uniaxial stress axis. The results show an almost negligible effect of tensile stress, which is normally unexpected, but a very pronounced effect of compressive stress. These results clearly indicate a limitation of the validity of the model based on magnetic domain wall motion. In an attempt to interpret these new results, the uniaxial stress effects on magnetostriction and magnetization curves were investigated, and the effect of tensile stress-induced magnetic dipolar fields was examined