FIELD: metallurgy.
SUBSTANCE: invention relates to metallurgy, namely to a method of producing a sheet of electrical steel with an oriented grain structure, which is used as material for iron cores of transformers. Steel billet is hot-rolled with the following chemical composition, wt.%: from 0.030 to 0.100 of C; from 0.80 to 7.00 of Si; from 0.01 to 1.00 of Mn; from 0 to 0.060 in total of S and Se; from 0.010 to 0.065 of acid-soluble Al; from 0.004 to 0.012 of N; from 0 to 0.30 of Cr; from 0 to 0.40 of Cu; from 0 to 0.50 of P; from 0 to 0.30 of Sn; from 0 to 0.30 of Sb; from 0 to 1.00 of Ni; from 0 to 0.008 of B; from 0 to 0.15 of V; from 0 to 0.20 of Nb; from 0 to 0.10 of Mo; from 0 to 0.015 of Ti; from 0 to 0.010 of Bi; the rest is iron and impurities, with production of hot-rolled steel sheet. Obtained sheet is subjected to hot annealing, etching and cold rolling. Then, decarbonisation annealing is carried out in atmosphere with degree of oxidation PH2O/PH2 of 0.01–0.15, at temperature of 750–900 °C during holding time of 10–600 s. Annealing separator is applied, which includes Al2O3 and MgO, with a value of MgO/(MgO+Al2O3) of 5–50 %, and an amount of hydrated water in the annealing separator of 1.5 wt.% or less, with subsequent drying. Finishing annealing is carried out at an oxidation degree of 0.00010–0.2, when the atmosphere includes hydrogen, or a dew point of 0 °C or less, when the atmosphere consists of an inert gas without hydrogen. Excess annealing separator is removed and an insulating coating is formed by applying a solution comprising mainly phosphate or colloidal silica, baking solution at 350–600 °C, and then subjecting it to heat treatment at 800–1,000 °C.
EFFECT: sheet has excellent magnetic characteristics and coating adhesion.
7 cl, 1 dwg, 10 tbl
