Experimental characterization of the effect of uniaxial stress on magnetization and iron losses of electrical steel sheets cut by punching process

The effect of uniaxial stress on iron losses of M400-50A grade non-oriented electrical steel sheets cut by punching process is experimentally studied. Samples cut along the rolling and transverse directions and having different number of cutting edges are used for this purpose. Measurements are carried out in the range of 10-100 Hz frequency of sinusoidal excitations at different magnetization levels under varying uniaxial stress by using a single sheet tester. The iron losses are obtained from the measurements and comparative analyses are made for different cases. The study shows that the effect of stress on the iron losses of the punched samples varies depending on the degradation level that the samples have after the cutting process. By considering this varying effect, when the combined effect of stress and punching is analysed, it is observed that the iron losses increased up to 55.2% under compressive stress. It is also observed that the increase in the losses due to the effect of cutting can be recovered by applying tensile stress.