Method for producing grain-oriented electrical steel sheet

1 . A method for producing a grain-oriented electrical steel sheet, comprising:

subjecting a steel material to hot rolling to obtain a hot-rolled steel sheet, the steel material having a chemical composition containing by mass %,

C: 0.01% or more and 0.10% or less,

Si: 2.0% or more and 5.0% or less,

Mn: 0.01% or more and 0.50% or less,

(i) one or both groups of: group α: Al: 0.01% or more and 0.04% or less and N: 0.003% or more and 0.010% or less, and group β: one or both of S and Se: 0.005% or more and 0.100% or less in total, or (ii) Al: 0.010% or less, N: 0.0060% or less, and one or both of S and Se: 0.010% or less in total,

optionally at least one selected from the group consisting of Ni: more than 0% and 1.50% or less, Cr: more than 0% and 0.50% or less, Cu: more than 0% and 0.50% or less, P: more than 0% and 0.50% or less, Sb: more than 0% and 0.50% or less, Sn: more than 0% and 0.50% or less, Bi: more than 0% and 0.50% or less, Mo: more than 0% and 0.50% or less, B: more than 0 ppm and 25 ppm or less, Nb: more than 0% and 0.020% or less, V: more than 0% and 0.010% or less, Zr: more than 0% and 0.10% or less, Co: more than 0% and 0.050% or less, Pb: more than 0% and 0.0100% or less, As: more than 0% and 0.0200% or less, Zn: more than 0% and 0.020% or less, W: more than 0% and 0.0100% or less, Ge: more than 0% and 0.0050% or less, and Ga: more than 0% and 0.0050% or less,

with the balance being Fe and inevitable impurities;

subjecting the hot-rolled steel sheet to cold rolling once, or twice or more with intermediate annealing in between, to obtain a cold-rolled steel sheet having a final sheet thickness;

then subjecting the cold-rolled steel sheet to decarburization annealing;

then applying an annealing separator to a surface of the steel sheet; and

then subjecting the steel sheet to final annealing, wherein

the following conditions are satisfied:

T

≤

-

4000

×

A

+

440

,

and

T

≤

360

,

wherein A denotes an average C content in mass % in a region ranging from 1/10 to ½ of a sheet thickness below the surface of the steel sheet after subjection to annealing preceding final cold rolling and before subjection to the final cold rolling, and T denotes a time in hours from just after the completion of the annealing preceding the final cold rolling to just before the start of the final cold rolling, and

after the final cold rolling and before the decarburization annealing, pickling treatment is performed with a treatment solution having an acid with a concentration of 1 mass % or more and 20 mass % or less and an Fe ion content of 2 mass % or more and 15 mass % or less, wherein the acid is selected from the group consisting of phosphoric acid, hydrochloric acid, sulfuric acid, and nitric acid.

2 . The method for producing a grain-oriented electrical steel sheet according to claim 1 , wherein

the decarburization annealing is divided into earlier-stage annealing and later-stage annealing,

the earlier-stage annealing is performed in an annealing atmosphere with an atmospheric oxidizability P(H 2 O)/P(H 2 ) of 0.3 or more and 0.7 or less, and

the later-stage annealing is performed in an annealing atmosphere with an atmospheric oxidizability P(H 2 O)/P(H 2 ) of 0.005 or more and 0.2 or less.