Análise do efeito do grau de redução sobre as propriedades magnéticas e mecânicas do aço elétrico de grão não orientado 3,3%Si

Abstract

In this work, the effect of cold and hot reduction degrees on the magnetic and mechanical properties of Non-Grain Oriented electrical steel (NGO) with 3.3wt%Si was evaluated. For this purpose, 28mm rough samples were submitted in laboratory to finishing hot rolling for thicknesses of 2.5, 2.1, 1.5 and 1.2mm. After that,they were hot band annealed, pickled, cold rolled to thicknesses of 0.50 and 0.25mm and final annelead. Hot band and final annealing are done at a fixed temperature of 1000°C and 940°C, respectively. Magnetic properties were determined by using a single sheet tester, the mechanical properties by tensile test, the volumetric fraction of the fibers α, γ e η by X-ray diffraction, the microstructure and the grain size measurements by optical microscopy. The results demonstrated that the behavior of B50 and yield strength tended to be antagonistic with strong influence of the η/γ ratio and grain size on these parameters. Finally, the cold rolling reduction which obtains the best balance between magnetic properties (core loss at 1T/400Hz and B50) and mechanical properties (yield strength) is 83.3% for 0.25mm and 66.7% for 0.50mm, both cases for the same hot thickness of 1.50mm.