US 12,325,892 B2
Method for manufacturing a grain-oriented electrical steel sheet
Yasuyuki Hayakawa, Tokyo (JP); Masanori Takenaka, Tokyo (JP); and Takeshi Imamura, Tokyo (JP)
Assigned to JFE STEEL CORPORATION, Tokyo (JP)
Filed by JFE STEEL CORPORATION, Tokyo (JP)
Filed on Oct. 5, 2022, as Appl. No. 17/938,047.
Application 17/938,047 is a division of application No. 16/333,729, granted, now 11,560,603, previously published as PCT/JP2017/034170, filed on Sep. 21, 2017.
Claims priority of application No. 2016-184742 (JP), filed on Sep. 21, 2016.
Prior Publication US 2023/0045475 A1, Feb. 9, 2023
Int. Cl. C21D 9/46 (2006.01); C21D 6/00 (2006.01); C21D 8/00 (2006.01); C21D 8/12 (2006.01); C22C 38/00 (2006.01); C22C 38/02 (2006.01); C22C 38/04 (2006.01); C22C 38/06 (2006.01); C22C 38/08 (2006.01); C22C 38/14 (2006.01); C22C 38/20 (2006.01); C22C 38/22 (2006.01); C22C 38/26 (2006.01); C22C 38/34 (2006.01); C22C 38/60 (2006.01); H01F 1/147 (2006.01); H01F 1/16 (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 8/005 (2013.01); C21D 8/1222 (2013.01); C21D 8/1233 (2013.01); C21D 8/1238 (2013.01); C21D 8/1266 (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 38/02 (2013.01); C22C 38/04 (2013.01); C22C 38/06 (2013.01); C22C 38/08 (2013.01); C22C 38/14 (2013.01); C22C 38/20 (2013.01); C22C 38/22 (2013.01); C22C 38/26 (2013.01); C22C 38/34 (2013.01); C22C 38/60 (2013.01); H01F 1/147 (2013.01); H01F 1/16 (2013.01); C22C 2202/02 (2013.01); Y02P 10/20 (2015.11)] 4 Claims
 
1. A method for manufacturing a grain-oriented electrical steel sheet, the method comprising:
providing a steel slab, the steel slab having a chemical composition containing, in mass %,
C: 0.025% or more and 0.060% or less,
Si: 3.0% or more and 4.0% or less,
Mn: 0.05% or more and 0.50% or less,
sol. Al: less than 0.01%,
N: less than 0.006%, and
S and Se: less than 0.010% in total,
with the balance being Fe and inevitable impurities;
optionally heating the steel slab to a heating temperature of 1300° C. or less;
subjecting the steel slab to hot rolling to obtain a hot-rolled steel sheet;
subjecting the hot-rolled steel sheet to hot band annealing;
subjecting the hot-rolled steel sheet annealed by the hot band annealing, to cold rolling to obtain a cold-rolled steel sheet with a final sheet thickness;
subjecting the cold-rolled steel sheet to primary recrystallization annealing to obtain a primary recrystallized steel sheet;
applying an annealing separator to the primary recrystallized steel sheet;
coiling the primary recrystallized steel sheet to which the annealing separator has been applied, to obtain a coil;
subjecting the coil to secondary recrystallization annealing, and
thereby producing the grain-oriented electrical steel sheet, wherein the grain-oriented electrical steel sheet has a carbon content of 0.005 mass % or less, an average value of a deviation angle

OG Complex Work Unit Math
calculated from a deviation angle α from ideal Goss orientation around an ND rotation axis and a deviation angle β from ideal Goss orientation around a TD rotation axis of 4.5° or less and an area ratio R62 of crystal grains with β≤0.50° of 15% or less,
wherein
a residence time from 900° C. to 700° C., t900-700° C., in an annealing before a final cold rolling is 6 seconds or more and 180 seconds or less,
an area ratio Rc of carbide with a particle size of 1 μm or more at start of final cold rolling in the cold rolling is 2.0% to 15%,
an average crystal grain size D at the start of the final cold rolling is 50 μm or more and 300 μm or less, and
a maximum temperature Tmax in the final cold rolling is 150° C. or more.