SHEET OF ANISOTROPIC ELECTROTECHNICAL STEEL AND METHOD FOR MANUFACTURE THEREOF Russian patent published in 2022 - IPC C21D8/12 C22C38/00 H01F1/16 

FIELD: metallurgy.

SUBSTANCE: invention relates to the field of metallurgy, namely, to the manufacture of a sheet of anisotropic electrotechnical steel used as a material for iron cores of transformers. In order to manufacture the main silicon steel sheet, a steel slab is heated to a temperature of 1,280°C or lower and hot-rolled, resulting in a hot-rolled steel sheet subjected to annealing in a hot state. The hot-rolled steel sheet is cold-rolled once or twice or more times with intermediate annealing between said times, resulting in a cold-rolled steel sheet subjected to decarbonising annealing and nitriding in the process of nitriding annealing. In the process of cold rolling, the degree of compression in finishing cold rolling is 80% or more, the roughness Ra of the roll in the last pass is 0.40 mcm or less, and the compression in the last pass is 10% or more. An annealing separator containing Al₂O₃ and MgO is applied onto the surface of the decarbonised and annealed sheet, followed by a final annealing with subsequent treatment of the surface by removing the excess annealing separator from the surface of the steel sheet subjected to final annealing, resulting in a main sheet of silicon steel used to manufacture a sheet of anisotropic electrotechnical steel. In the process of final annealing, the oxidation state is 0.0001 to 0.2 when the annealing atmosphere contains hydrogen, or the dew point is 0°C or lower when the annealing atmosphere consists of a hydrogen-free inert gas. In the process of surface treatment, a solution containing less than 20 wt.% total of one or two or more from sulphuric acid, hydrochloric acid, phosphoric acid, nitric acid, hypochlorous acid, an aqueous solution of chromium oxide, chromium sulphate, permanganate, peroxosulphuric, acid and peroxophosphate is used, wherein the temperature of the solution is set to 50–80°C, and the submersion time is set to 1–30 seconds.

EFFECT: manufactured sheets exhibit excellent magnetic characteristics.

12 cl, 3 dwg, 21 tbl, 2 ex