Ural Federal University (Ekaterinburg, Russia):

Yu. N. Loginov, Dr. Eng., Prof, e-mail: j.n.loginov@urfu.ru
M. P. Puzanov, Post-graduate student

The effect of the anisotropy of the properties on the stressstrain state during the rolling of a strip of electrical steel is investigated. Formulations of the defining relations for anisotropic materials were used, from which the need to measure the strength properties of the material in different directions followed. In the experimental part of the work, the electrical steel of industrial production of the following chemical composition was used to determine the anisotropy coefficients of the material, %: 0.03 C; 3.2 Si; 0.3 Mn; 0.01 Ni; 0.015 Al; 0.002 Cr; 0.55 Cu; 0.003 Ti; 0,01 N. The strip of the investigated steel was rolled in the cold state with an initial thickness of 2.50 mm to a final thickness of 0.70 mm in 4 passes with a total reduction of 72%. To calculate the coefficients of the Hill's plasticity equation, it is required to conduct the tests in the direction normal to the plane of the sheet, so the most suitable method for studying the mechanical properties of a thin sheet material is to measure the microhardness. From the cold-rolled sheet, flat samples measuring 0.70 × 10 × 20 mm with different orientations relative to the coordinate system of the rolling process were prepared. The tests were carried out on the Shimadzu HMV-G21DT unit by pressing a tetrahedral pyramid with a square base with the method of the reconstructed print. The value of the static load was 0.049 N. Based on the results of the statistical processing of the test results, the dependence of the average hardness of the cold-rolled electrical steel on the measurement direction was obtained. Using the known relationship between the conditional yield strength of the material and the hardness, the coefficients of the Hill's plasticity equation were established. In the theoretical part of the work, the finite element method was used to solve the boundary value problem of thin-film rolling for an isotropic and anisotropic medium with the assignment of the corresponding boundary conditions. The distribution of stresses and deformations in the rolled strip is given. Differences in the stress-strain state of the metal in the deformation zone are revealed. The longitudinal stresses for rolling an anisotropic strip were higher by 40%, and the stresses along the thickness of the rolled steel were lower by 13% than the corresponding parameters for rolling an isotropic strip.
The study was made with partial financial support of the Program 211 of the RF Government (agreement № 02.A03.21.0006).

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