Soft magnetic or silicon electrical steel sheets are characterized by low total losses and high relative permeability. Depending on the magnetic properties and purpose of use, electrical steels are classified into two groups, grain-oriented and non-grain-oriented. Non-oriented electrical steel is used to make cores for electric motors that can be found in various areas of our everyday life. In addition to losses and relative permeability, the efficiency of electrical machines is also influenced by the chemical content of elements, cutting, sheet thickness etc.
In diploma work, we researched the influence of chemical composition and boundary effect on the magnetic properties of non-oriented electrical steel sheets. The focus was on the influence of silicon concentration and total length of the edge at the same length of the sample. The material that we used was from four different suppliers, which differed in silicon content. Two grades of electrical steels were used: M400-50A and M530-50A. Magnetic measurements were performed using the Epstein frame method on samples with a different number of cutting edges. Cutting of samples to half, one-third and one-fifth of their total width of 30 mm was carried out with a punching tool. From electromagnetic measurements, we plotted the curves of magnetization, relative permeability and total power losses. Furthermore, we performed measurements of mechanical properties, such as hardness (HV) and tensile test. Chemical composition of the material was determined with an optical emission spectrometer (OES). We also prepared samples to determine the deformed zone using an optical microscope. We analysed the fracture surface morphology with the help of a scanning electron microscope.
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