Non-oriented electrical steel sheet and manufacturing method thereof
View Patent ↗A manufacturing method of a non-oriented electrical steel sheet includes: performing finish annealing of a cold-rolled steel strip; and forming a tension-applying type insulating film of not less than 1 g/m 2 and not more than 6 g/m 2 on a surface of the cold-rolled steel strip. The performing the finish annealing includes forming an oxide layer containing Al 2 O 3 or (Al, Cr) 2 O 3 and having a thickness of not less than 0.01 μm and not more than 0.5 μm on the surface of the cold-rolled steel strip with setting a temperature of the cold-rolled steel strip to not lower than 800° C. and not higher than 1100° C. in an atmosphere where when the total content of Si and Al of the cold-rolled steel strip is represented as X (mass %), a partial pressure ratio of water vapor to hydrogen is equal to or less than 0.005×X 2 .
1. A manufacturing method of a non-oriented electrical steel sheet comprising:
performing finish annealing of a cold-rolled steel strip; and
forming a tension-applying type insulating film of not less than 1 g/m 2 and not more than 6 g/m 2 on a surface of the cold-rolled steel strip, wherein
the cold-rolled steel strip contains:
Si, Al, and Cr: not less than 2 mass % and not more than 6 mass % in total content;
Mn: not less than 0.1 mass % and not more than 1.5 mass %;
C: equal to or less than 0.005 mass %; and
a balance of Fe and inevitable impurities, and
the performing the finish annealing includes forming an oxide layer containing Al 2 O 3 or (Al, Cr) 2 O 3 and having a thickness of not less than 0.01 μm and not more than 0.5 μm on the surface of the cold-rolled steel strip with setting a temperature of the cold-rolled steel strip to not lower than 800° C. and not higher than 1100° C. in an atmosphere where when the total content of Si and Al of the cold-rolled steel strip is represented as X (mass %), a partial pressure ratio of water vapor to hydrogen is equal to or less than 0.005×X 2 .
2. The manufacturing method of a non-oriented electrical steel sheet according to claim 1 , wherein the forming the insulating film comprises, after the performing the finish annealing:
applying a coating solution to the surface of the cold-rolled steel strip; and
performing baking of the coating solution with setting the temperature of the cold-rolled steel strip to not lower than 800° C. and not higher than 1100° C.
3. The manufacturing method of a non-oriented electrical steel sheet according to claim 2 , wherein the coating solution contains phosphate and colloidal silica.
4. The manufacturing method of a non-oriented electrical steel sheet according to claim 2 , wherein the coating solution contains boric acid and an alumina sol.
5. The manufacturing method of a non-oriented electrical steel sheet according to claim 1 , wherein the forming the insulating film comprises:
applying a coating solution to the surface of the cold-rolled steel strip before the performing the finish annealing; and
performing baking of the coating solution during the finish annealing.
6. The manufacturing method of a non-oriented electrical steel sheet according to claim 5 , wherein the coating solution contains phosphate and colloidal silica.
7. The manufacturing method of a non-oriented electrical steel sheet according to claim 5 , wherein the coating solution contains boric acid and an alumina sol.
8. The manufacturing method of a non-oriented electrical steel sheet according to claim 1 , wherein the total content of Al and Cr of the cold-rolled steel strip is equal to or more than 0.8 mass %.
9. The manufacturing method of a non-oriented electrical steel sheet according to claim 2 , wherein the total content of Al and Cr of the cold-rolled steel strip is equal to or more than 0.8 mass %.
10. The manufacturing method of a non-oriented electrical steel sheet according to claim 3 , wherein the total content of Al and Cr of the cold-rolled steel strip is equal to or more than 0.8 mass %.
11. The manufacturing method of a non-oriented electrical steel sheet according to claim 4 , wherein the total content of Al and Cr of the cold-rolled steel strip is equal to or more than 0.8 mass %.
12. The manufacturing method of a non-oriented electrical steel sheet according to claim 5 , wherein the total content of Al and Cr of the cold-rolled steel strip is equal to or more than 0.8 mass %.
13. The manufacturing method of a non-oriented electrical steel sheet according to claim 6 , wherein the total content of Al and Cr of the cold-rolled steel strip is equal to or more than 0.8 mass %.
14. The manufacturing method of a non-oriented electrical steel sheet according to claim 7 , wherein the total content of Al and Cr of the cold-rolled steel strip is equal to or more than 0.8 mass %.