Determination of Magnetic Ductility and Residual Magnetization of Steels

The phenomenon of magnetic ductility (magnetic aftereffect of the material) is a certain delay in the magnetization following the change of the magnetic field applied to the ferromagnet. Speaking about the magnetic aftereffect, we usually exclude from this concept the phenomena associated with changes in magnetic properties because of changes in the material itself under the action of natural diffusion or metallurgical processing, e.g., that causes the separation of phases. It was found in the papers by Vonsovsky, Tikazumi, Mishina, and others that the change in magnetization with time depends on the thermodynamic state of the body—its phase composition, temperature, deformation, and the concentration of impurities, including hydrogen. Thus, the measurement of magnetic aftereffect in relation to other physical processes is of some interest to be used when developing new non-destructive testing methods for assessing the state of ferromagnetic materials in products and structural elements operating in different environments, especially in hydrogen-containing. This chapter presents the results of the evaluation of the magnetic ductility and residual magnetization of ferromagnets, obtained on samples of various structural steels.