Selected methods of detection of fatigue degradation in ferromagnetic steels

The fatigue degradation of ferromagnetic steels proceeds with the changes of electrical (γ) and/or magnetic (μ) parameters. The article presents some selected issues of research into correlations between the magnetic parameters and the material fatigue degree, in operating conditions as well as quantitatively controlled in laboratory conditions. In order to identify and assess the effects of fatigue, a methodology of quantitative description of material defect degree was developed. According to the developed methodology, a set of standard samples with specified value of their defect degree was prepared. There were tested and analyzed the microstructural aspects of degradation process taking place in the operating conditions under the influence of variable mechanical, thermal and environmental loads, and also in the conditions of single-variable loads performed in the laboratory.