US 12,291,758 B2
Method for producing grain-oriented electrical steel sheet
Yuiko Ehashi, Tokyo (JP); Yukihiro Shingaki, Tokyo (JP); Hirokazu Sugihara, Tokyo (JP); and Soshi Yoshimoto, Tokyo (JP)
Assigned to JFE STEEL CORPORATION, Tokyo (JP)
Appl. No. 17/604,830
Filed by JFE STEEL CORPORATION, Tokyo (JP)
PCT Filed Apr. 22, 2020, PCT No. PCT/JP2020/017312
§ 371(c)(1), (2) Date Oct. 19, 2021,
PCT Pub. No. WO2020/218328, PCT Pub. Date Oct. 29, 2020.
Claims priority of application No. 2019-081640 (JP), filed on Apr. 23, 2019.
Prior Publication US 2022/0042137 A1, Feb. 10, 2022
This patent is subject to a terminal disclaimer.
Int. Cl. C21D 9/46 (2006.01); C21D 6/00 (2006.01); C21D 8/12 (2006.01); C22C 38/00 (2006.01); C22C 38/04 (2006.01); C22C 38/06 (2006.01); C22C 38/20 (2006.01); C22C 38/22 (2006.01); C22C 38/24 (2006.01); C22C 38/26 (2006.01); C22C 38/34 (2006.01); C22C 38/60 (2006.01); H01F 1/147 (2006.01)
CPC C21D 9/46 (2013.01) [C21D 6/001 (2013.01); C21D 6/002 (2013.01); C21D 6/005 (2013.01); C21D 6/008 (2013.01); C21D 8/1222 (2013.01); C21D 8/1233 (2013.01); C21D 8/1261 (2013.01); C21D 8/1272 (2013.01); C21D 8/1283 (2013.01); C22C 38/001 (2013.01); C22C 38/002 (2013.01); C22C 38/008 (2013.01); C22C 38/04 (2013.01); C22C 38/06 (2013.01); C22C 38/20 (2013.01); C22C 38/22 (2013.01); C22C 38/24 (2013.01); C22C 38/26 (2013.01); C22C 38/34 (2013.01); C22C 38/60 (2013.01); H01F 1/147 (2013.01); C22C 2202/02 (2013.01)] 8 Claims
 
1. A method for producing a grain-oriented electrical steel sheet comprising a series of steps
heating a steel slab having a component composition comprising C: 0.020 to 0.10 mass %, Si: 2.0 to 4.0 mass %, Mn: 0.005 to 0.50 mass %, Al: less than 0.010 mass %, N, S and Se: less than 0.0050 mass % each, and the remainder being Fe and inevitable impurities to a temperature of not higher than 1280° C.,
hot rolling the steel slab to form a hot-rolled sheet,
subjecting the hot-rolled sheet to a hot-band annealing, and then a single cold rolling or two or more cold rollings having an intermediate annealing between each cold rolling to form a cold-rolled sheet having a final sheet thickness,
subjecting the cold-rolled sheet to a primary recrystallization annealing combined with a decarburization annealing,
applying an annealing separator onto a surface of the steel sheet, and
subjecting the steel sheet to a finish annealing and a flattening annealing, wherein
a rapid cooling is conducted at an average cooling rate of not less than 200° C./s throughout the entire temperature range of from 800° C. to 300° C. in a cooling process from a maximum achieving temperature of above 800° C. in at least one process of the hot-band annealing and the intermediate annealing, and
subsequently to the rapid cooling, a cooling is conducted from 300° C. to 100° C. at an average cooling rate of 5 to 40° C./s.