ANALYSIS OF CHANGES IN RESIDUAL MAGNETIC FIELD IN LOADED NOTCHED SAMPLES

The residual magnetic field (RMF) of a ferromagnetic element is a value which can be affected by several physical effects. These are: the magneto-mechanical effect, the effect of outer magnetic field leakage caused by discontinuity or structural inhomogeneity of the material, and the processes of mutual interacting of magnetic fields with dislocations and their cumulation. The following paper presents the results of measurements of the residual magnetic field of mechanically notched samples exposed to tensile loads. The distribution of the residual magnetic field was mapped for subsequent loads applied. There were substantial changes in the pattern of isolines and in all the components of the RMF of the samples in comparison to the initial state. That indicates a high sensitivity of the RMF to any changes in stress. The results obtained were compared to the calculated maps of stresses and deformation. A correlation was found out between these values. Measurements of the residual magnetic field make it possible to determine the notch effect and a qualitative determination of the distribution of inner stresses.