Express diagnostic method of the stress state of weakly magnetized ferromagnetic rods

A method for express diagnostics of weakly magnetized ferro-magnetic rods is proposed. It is based on measuring the stray magnetic field of the rod. We analyze the inverse magnetostatic problem and formulate the conditions when its regularization is possible. In this case, it is possible to connect the value of the average transverse component of magnetization with the results of the measured stray magnetic field. The distributions of transverse magnetization values were experimentally studied using rods made of SV08G2S [transliterated from Russian] and ER-308LSi steels as an example. The studied samples were subjected to impact plastic deformation, tensile deformation, and torsion deformation. It is shown that this method allows to register areas with stress concentrations without additional magnetization of the test sample. A feature of the method is the use of once calculated system functions without solving large systems of equations and using unstable spectral methods. The method is applicable for cylindrical objects of small radius far from the edge of the test sample, when the magnetization in the cross section of the sample can be considered as constant.