FIELD: metallurgy.
SUBSTANCE: invention relates to the field of metallurgy, namely, to a method for producing sheet of electrotechnical steel with an oriented grain structure, used as the material of iron cores of transformers. A steel workpiece is hot-rolled, with a chemical composition containing, wt.%: from 0.030 to 0.100 C, from 0.80 to 7.00 Si, from 0.01 to 1.00 Mn, from 0 to 0.060 in total S and Se, from 0.010 to 0.065 acid-soluble Al, from 0.004 to 0.012 N, from 0 to 0.30 Cr, from 0 to 0.40 Cu, from 0 to 0.50 P, from 0 to 0.30 Sn, from 0 to 0.30 Sb, from 0 to 1.00 Ni, from 0 to 0.008 B, from 0 to 0.15 V, from 0 to 0.20 Nb, from 0 to 0.10 Mo, from 0 to 0.015 Ti, from 0 to 0.010 Bi, the rest iron and impurities, to produce a hot-rolled steel sheet, and subsequently cold-rolled to produce a cold-rolled steel sheet. Decarburising annealing is conducted in an atmosphere with a degree of oxidation PH2O/PH2 of 0.18 to 0.80 at a temperature of 750 to 900°C and a holding time of 10 to 600 s to produce a decarburised annealed steel sheet. An annealing separator including MgO is applied and dried. Final annealing is conducted by holding the sheet at 1,100 to 1,200°C for 10 hours or more in a mixed gas atmosphere including 50 vol.% or more of hydrogen. Excess annealing separator is removed by washing with water using a solution with an inhibitor constituting at least one of triethanolamine, rosin amine, or mercaptan, and the amount of iron hydroxide and iron oxide on the surface is controlled so as to be 0.9 g/m2 or less per side. The sheet is smoothed after removing the excess annealing separator at 1,000°C or higher in a mixed gas atmosphere including 50 vol.% or more of hydrogen or carbon monoxide. An insulating coating is formed by applying a solution including mainly phosphate or colloidal silica, baking at 350 to 600°C, and subjecting to heat treatment at 800 to 1,000°C.
EFFECT: sheet has high magnetic characteristics and coating adhesion.
6 cl, 1 dwg, 10 tbl
