Effect of Hardness and Thickness of Nonoriented Electrical Steel Sheets on Iron Loss Deterioration by Shearing Process

The influence of the shearing process on the iron loss of nonoriented electrical steels with the thickness of 0.20-0.50 mm and the hardness of HV150-220 was investigated. The deterioration ratio of iron loss was clearly smaller in thinner or harder samples. The deterioration of iron loss and the droop height, reflecting the amount of plastic deformation, displayed a good relationship irrespective of the material thickness and the hardness. This is a well-known statement that an elastic stress affects losses of steel sheets. The effective plastic strain distribution through the thickness of the sheet calculated by the elastic-plastic analysis based on the finite-element method (FEM) coincided with the actual measurement result of hardness increase, reflecting the distribution of plastic deformation. From the evaluation of elastic-plastic deformation by the FEM, it was also shown that the material thickness and hardness influence the elastic strain distribution as a plastic strain, and that the droop height reflects both the amount of plastic strain and the amount of elastic strain.