Grain-oriented electromagnetic steel sheet

Claim 2

An AlN and MnS inhibited grain-oriented electrical steel sheet, said steel sheet consisting essentially of from 2.5% to less than 4.0% silicon, from 0.03% to less than 0.15% manganese, from 0.03% to less than 0.5% tin, and from 0.02% to less than 0.3% copper, the remainder being iron and unavoidable impurities; wherein the proportion of tin to copper is in the range of from 1:0.5 to 1:1; and wherein said sheet has disposed on the surface thereof an electrical insulation and tension producing coating.

Claim 3

An AlN and MnS inhibited grain-oriented electrical steel sheet according to claim 1 wherein said proportion of tin to copper is approximately 1:0.75.

Claim 4

An AlN and MnS inhibited grain-oriented electrical steel sheet according to claim 1 wherein the tin content is from 0.5% to 0.2%.

Claim 5

An AlN and MnS inhibited grain-oriented electrical steel sheet according to claim 1 wherein the copper content is from 0.05% to 0.15%.

Claim 6

An AlN and MnS inhibited grain-oriented electrical steel sheet according to claim 1 wherein the ASTM grain size is between No. 3 and No. 5.

Claim 7

An AlN and MnS inhibited grain-oriented electrical steel sheet according to claim 1 wherein the surface coating exhibits a tension of greater than 600 g/mm 2 .

Claim 8

A silicon steel slab for processing into a grain-oriented electrical steel sheet, said slab consisting essentially of not more than 0.085% carbon, from 2.5% to 4.0% silicon, from 0.3% to 0.15% manganese, from 0.010% to 0.050% sulfur, from 0.010% to 0.050% acid-soluble aluminum, and from 0.0045% to 0.012% nitrogen, and additionally containing from 0.03% to 0.5% tin and 0.02% to 0.3% copper, with the proportion of tin to copper being in the range of from 1:0.5 to 1:1, the balance being iron and unavoidable impurities.

Claim 9

A silicon steel slab for processing into a grain-oriented electrical steel sheet, said slab consisting essentially of not more than 0.085% carbon, from 2.5% to 4.0% silicon, from 0.3% to 0.15% manganese, from 0.010% to 0.050% sulfur, from 0.010% to 0.050% acid-soluble aluminum, and from 0.0045% to 0.012% nitrogen, and additionally containing from 0.03% to 0.5% tin and 0.02% to 0.3% copper, with the proportion of tin to copper being in the range of from 1:0.5 to 1:1, the balance being iron and unavoidable impurities.

Claim 10

A silicon steel slab according to claim 7 wherein said proportion of tin to copper is approximately 1:0.75.

Claim 11

A silicon steel slab according to claim 7 wherein the tin content is from 0.05% to 0.2%.

Claim 12

A silicon steel slab according to claim 7 wherein the copper content is from 0.05% to 0.15%.

Claim 13

An AlN and MnS inhibited grain-oriented electrical steel sheet, said steel sheet consisting essentially of from 2.5% to less than 4.0% silicon, from 0.03% to less than 0.15% manganese, from 0.03% to less than 0.5% tin, and from 0.02% to less than 0.3% copper, the remainder being iron and unavoidable impurities; wherein the proportion of tin to copper is in the range of from 1:0.5 to 1:1; and wherein said sheet has disposed on the surface thereof an electrical insulation and tension producing coating; said grain-oriented electrical steel sheet being produced by the process of: hot rolling a slab consisting essentially of not more than 0.085% carbon, from 2.5% to 4.0% silicon, 0.03% to 0.15% manganese, from 0.010% to 0.05% sulfur from 0.01% to 0.050% acid-soluble aluminum, from 0.0045% to 0.012% nitrogen, from 0.03% to 0.5% tin, from 0.02% to 0.3% copper, the remainder being iron and unavoidable impurities with the proportion of tin to copper being in the range of from 1:0.5 to 1:1, to form a hot rolled strip; precipitation annealing the hot-rolled strip at a temperature of from 950° C. to 1200° C. from 30 seconds to 30 minutes, followed by rapid cooling so as to precipitate AlN; subjecting the thus annealed strip to a final cold rolling with a high reduction ratio of from 80% to 95% including an aging step between cold rolled passes; subjecting the cold rolled strip to decarburization annealing; applying an annealing separator to the decarburized-annealed strip; subjecting the decarburization-annealed strip, on which said annealing separator is applied, to final annealing; and applying a liquid as a surface coating on the final annealed strip, said liquid being selected to provide electrical insulation and tension on the produced surface-coated grain-oriented electrical steel strip.

Claim 14

An AlN and MnS inhibited grain-oriented electrical steel sheet, said steel sheet consisting essentially of from 2.5% to less than 4.0% silicon, from 0.03% to less than 0.15% manganese, from 0.03% to less than 0.5% tin, and from 0.02% to less than 0.3% copper, the remainder being iron and unavoidable impurities; wherein the proportion of tin to copper is in the range of from 1:0.5 to 1:1; and wherein said sheet has disposed on the surface thereof an electrical insulation and tension producing coating; said grain-oriented electrical steel sheet being produced by the process of: hot rolling a slab consisting essentially of not more than 0.085% carbon, from 2.5% to 4.0% silicon, 0.03% to 0.15% manganese, from 0.010% to 0.05% sulfur from 0.01% to 0.050% acid-soluble aluminum, from 0.0045% to 0.012% nitrogen, from 0.03% to 0.5% tin, from 0.02% to 0.3% copper, the remainder being iron and unavoidable impurities with the proportion of tin to copper being in the range of from 1:0.5 to 1:1, to form a hot rolled strip; precipitation annealing the hot-rolled strip at a temperature of from 950° C. to 1200° C. from 30 seconds to 30 minutes, followed by rapid cooling so as to precipitate AlN; subjecting the thus annealed strip to a final cold rolling with a high reduction ratio of from 80% to 95% including an aging step between cold rolled passes; subjecting the cold rolled strip to decarburization annealing; applying an annealing separator to the decarburized-annealed strip; subjecting the decarburization-annealed strip, on which said annealing separator is applied, to final annealing; and applying a liquid as a surface coating on the final annealed strip, said liquid being selected to provide electrical insulation and tension on the produced surface-coated grain-oriented electrical steel strip.

Claim 15

An AlN and MnS inhibited grain-oriented electrical steel strip according to claim 11 wherein the ASTM grain size is between No. 3 and No. 5.

Claim 16

An AlN and MnS inhibited grain-oriented electrical steel strip according to claim 11 wherein the surface coating exhibits a tension of greater than 600 g/mm 2 .

Claim 17

An AlN and MnS inhibited grain-oriented electrical steel sheet according to claim 11 wherein said coating liquid consists essentially of phosphoric acid, chromic acid and aluminum phosphate.

Claim 18

An AlN and MnS inhibited grain-oriented electrical steel sheet according to claim 11 wherein said surface coated steel sheet is further subjected to the step of flattening annealing.