Abstract
A magnetic probe containing a Hall sensor and pickup coil was developed, and its accuracy was confirmed by comparison with standard ring sample results under zero stress. The magnetic minor hysteresis loops of a lowcarbon steel plate sample were measured by using this probe under uniaxial tensile stresses. It was found that both the coercivity Hc and hysteresis loss WF can be measured accurately by means of a magnetic probe. In the perfectly elastic region, from 0 to 90 MPa, Hc and WF decrease with increasing external stresses due to domain re-orientation, and they start to increase a little in the micro-plastic range. In the plastic stage, Hc and WF increase almost linearly with external stresses as a result of dislocation pinning effects. This clear relationship between magnetic properties and external stresses is also valid for NDE applications.
