Effect of applied stresses on magnetostriction of low carbon steel

Abstract

We have measured the magnetostriction of low carbon steel specimens while applying magnetic fields, being both parallel and perpendicular to the uniaxial applied stress. An individual domain of a polycrystalline steel is elongated in its magnetization direction, which coincides with one of the crystallographic axes, 〈100〉. The magnetization appears as a result of the domain wall movement induced by the applied magnetic field. The rotation of the domain magnetization participates, when the field becomes larger. As the magnetic field is increased, the magnetostriction in the magnetization direction first increases and then shows a maximum when the rotation of the domain magnetization starts to occur. Since the stress affects the domain structure through magnetoelastic interaction, the maximum magnetostriction shows the stress dependence. The magnetoelastic interaction tends to increase the volume of the domains being either parallel to the tensile stress or perpendicular to the compressive stress. The amount of the domain wall movement, equivalently the maximum magnetostriction, is thus larger for the magnetization which is either perpendicular to the tensile stress or parallel to the compressive stress. In the experiment, the maxima of magnetostriction, up to 17 × 10 −6, were measured with sufficient accuracy using semiconductor strain gauges attached to the specimens. The results support the above physical prediction. We found that the stress dependence of the maxima is almost insensitive to the relation between the rolling direction and the loading direction, which ensures that the magnetostriction method is suitable for the residual stress measurement.