Влияние геометрии полосы анизотропной электротехнической стали на ее магнитные свойства

Abstract

The impact of the geometry (mainly the surface roughness) of cold rolled strips of anisotropic electrical (transformer) steel of domestic production (technical soft magnetic bcc alloy Fe - 3 wt.% Si with an edge crystallographic texture (110)[001]) on the magnetic properties (particularly on electromagnetic induction B 800 and specific magnetic losses P 1 7/ 50 ) is studied. It is shown that corrugations are formed on the surface of steel strips during cold rolling to a final thickness of 0.23 - 0.30 mm with a reduction of 50 - 70%. As a rule, their ridges and valleys are perpendicular to the direction of rolling and have a wavy form. Formation of the relief is attributed to the gradient of the stress-strain state along the cross section of the strip and to the tightness of the flow of the surface layers at the end of the deformation region and inevitably accompanies the rolling process. The presence of corrugations like any other roughness on the strip surface reduces B 800 and increases P 1, 7/ 50 . We propose a method for elimination of the surface defects (including corrugations) of cold rolled steel strips after cold rolling, i.e., ironing, which can be carried out by drawing of strips with a small draft (~3%) in cold rolling mills with a disconnected work roll drive using coilers. Introduction of drawing into the transformer steel manufacture technology improves the magnetic properties of steel due to increased perfection of the crystallites (grains), increased sharpness of the edge(110)[001] texture and free movement of the boundaries of magnetic domains upon magnetic reversal. Ironing of the steel strips of nitride-copper melt (inhibitors - dispersed particles of AlN and CuMn 2 O 4 ) with a thickness of 0.30 mm increased B 800 up to 1.93 T and decreased P 1, 7/ 50 to 1.07 W/kg (thus improving the magnetic properties by 5.7 and 10%, respectively). The resulted properties of domestic steel production are not inferior to those of foreign steel.