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Non-oriented electrical steel sheets are the most often used materials in electrical rotary machines. Raw sheets must be formatted by various methods, e.g., punching, laser, spark or water stream cutting. Basic parameters of magnetic, electrical, and mechanical properties of the sheets are usually obtained from the producer, but namely magnetic properties are changed in dependence on additional machining processes. The aim of this study is to describe changes in magnetic properties after punching, laser or spark cutting of the original sheets M470-50A. The basic information about the structure of the cut edges of samples was obtained by optical microscopy and scanning electron microscopy. For the magnetic measurements toroidal samples were prepared by the mentioned technologies. The magnetic parameters were yielded from the measuring of magnetic hysteresis loops in dependence on saturation fields. The results are discussed from the point of view of applied cutting methods with the aim to obtain the best magnetic parameters and consequently determining the depth of the influenced material. After laser cutting, important decrease in remanence and increase in total losses were observed in comparison with the punched samples.

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The knowledge of magnetic and transport properties of construction steels for magnetic circuits plays an important role. Three different techniques: (i) flame spray, (ii) twin wire arc spray and (iii) powder mixture with halide activator were used to produce Si, CuSn6 and Si coatings, respectively, on the 41CrMo4 steel ring substrates. Immediately after the thermal spraying or inserting the steels into the powder mixture was used isothermal heat treatment at the temperatures of 800 °C / 6 hrs, 1000 °C / 4 hrs and 1250 °C / 2 hrs to produce the diffusion coatings. Several coating systems consisting of different phases and thicknesses were manufactured. Opto-digital microscope, scanning electron microscope and digital image analysis, second equipped with energy dispersive microanalyzer, were utilized to characterize the microstructure, chemical composition and thicknesses of the coatings. The influence of coatings on magnetic properties in the frequency range of 50-2000 Hz was also measured.