Method for producing grain-oriented electrical steel sheet

Patent metadata

Field	Value
Publication number	US-9617616-B2
Application number	US-201314415089-A
Country	US
Kind code	B2
Filing date	Jul 25, 2013
Priority date	Jul 26, 2012
Publication date	Apr 11, 2017
Grant date	Apr 11, 2017

Abstract

In a method for producing a grain-oriented electrical steel sheet by comprising a series of steps of hot rolling a raw steel material containing C: 0.002-0.10 mass %, Si: 2.0-8.0 mass % and Mn: 0.005-1.0 mass % to obtain a hot rolled sheet, subjecting the hot rolled steel sheet after or without hot band annealing to one stage cold rolling or two or more stage cold rollings including an intermediate annealing therebetween to obtain a cold rolled sheet having a final sheet thickness, subjecting the cold rolled sheet to decarburization annealing combined with primary recrystallization annealing, applying an annealing separator to the steel sheet surface and then subjecting to a final annealing, when rapid heating is performed at a rate of not less than 50° C./s in a range of 200-700° C. of the decarburization annealing, the cold rolled sheet is subjected to holding at any temperature of 250-600° C. for 1-10 seconds thereof to thereby produce a grain-oriented electrical steel sheet being low in the iron loss and small in the deviation of the iron loss value.

First claim

The invention claimed is:

1. A method for producing a grain-oriented electrical steel sheet, the method comprising:
hot rolling a raw steel material to obtain a hot rolled steel sheet, the raw steel material including:
C: 0.002-0.10, by mass %,
Si: 2.0-8.0, by mass %,
Mn: 0.005-1.0, by mass %,
Al: 0.010-0.050, by mass %,
N: 0.003-0.020, by mass %,
optionally, at least one of Se: 0.003-0.030, by mass %, and S: 0.002-0.03, by mass %, and
Fe and inevitable impurities;

optionally, hot band annealing the hot rolled steel sheet;
then, subjecting the hot rolled steel sheet after or without hot band annealing to one stage cold rolling or two or more stage cold rollings including an intermediate annealing therebetween to obtain a cold rolled steel sheet having a final sheet thickness;
subjecting the cold rolled steel sheet to decarburization annealing combined with primary recrystallization annealing, and
during the decarburization annealing:
the entire steel sheet is rapidly heated over the entire range of 200-700° C. at an average rate of 50° C./s or more,
during the rapid heating, the entire steel sheet is held at a temperature that is within the range of 250-600° C. for 1-10 seconds, and
the average heating rate of 50° C./s or more does not include the time during which the entire steel sheet is held at the temperature within the range of 250-600° C. for 1-10 seconds;

then, applying an annealing separator to a surface of the steel sheet; and
then, subjecting the steel sheet to a final annealing.

2. A method for producing a grain-oriented electrical steel sheet, the method comprising:
hot rolling a raw steel material to obtain a hot rolled steel sheet, the raw steel material comprising:
C: 0.002-0.10, by mass %,
Si: 2.0-8.0, by mass %,
Mn: 0.005-1.0, by mass %,
at least one selected from the group consisting of Se: 0.003-0.030, by mass % and S: 0.002-0.03, by mass %, and
Fe and inevitable impurities;

optionally hot band annealing the hot rolled steel sheet;
then, subjecting the hot rolled steel sheet after or without hot band annealing to one stage cold rolling or two or more stage cold rollings including an intermediate annealing therebetween to obtain a cold rolled steel sheet having a final sheet thickness;
subjecting the cold rolled steel sheet to decarburization annealing combined with primary recrystallization annealing, and
during the decarburization annealing:
the entire steel sheet is rapidly heated over the entire range of 200-700° C. at an average rate of 50° C./s or more,
during the rapid heating, the entire steel sheet is held at a temperature that is within the range of 250-600° C. for 1-10 seconds, and
the average heating rate of 50° C./s or more does not include the time during which the entire steel sheet is held at the temperature within the range of 250-600° C. for 1-10 seconds;

then, applying an annealing separator to a surface of the steel sheet; and
then, subjecting the steel sheet to a final annealing.

3. The method for producing a grain-oriented electrical steel sheet according to claim 1 , wherein the raw steel material further includes one or more selected from the group consisting of:
Ni: 0.010-1.50, by mass %,
Cr: 0.01-0.50, by mass %,
Cu: 0.01-0.50, by mass %,
P: 0.005-0.50, by mass %,
Sb: 0.005-0.50, by mass %,
Sn: 0.005-0.50, by mass %,
Bi: 0.005-0.50, by mass %,
Mo: 0.005-0.100, by mass %,
B: 0.0002-0.0025, by mass %,
Te: 0.0005-0.0100, by mass %,
Nb: 0.0010-0.0100, by mass %,
V: 0.001-0.010, by mass %, and
Ta: 0.001-0.010, by mass %.

4. The method for producing a grain-oriented electrical steel sheet according to claim 1 , wherein during the decarburization annealing:
during the rapid heating, the entire steel sheet is held at the temperature that is within the range of 250-600° C. for 1-5 seconds, and
the average heating rate of 50° C./s or more does not include the time during which the entire steel sheet is held at the temperature within the range of 250-600° C. for 1-5 seconds.

5. The method for producing a grain-oriented electrical steel sheet according to claim 2 , wherein the raw steel material further includes one or more selected from the group consisting of:
Ni: 0.010-1.50, by mass %,
Cr: 0.01-0.50, by mass %,
Cu: 0.01-0.50, by mass %,
P: 0.005-0.50, by mass %,
Sb: 0.005-0.50, by mass %,
Sn: 0.005-0.50, by mass %,
Bi: 0.005-0.50, by mass %,
Mo: 0.005-0.100, by mass %,
B: 0.0002-0.0025, by mass %,
Te: 0.0005-0.0100, by mass %,
Nb: 0.0010-0.0100, by mass %,
V: 0.001-0.010, by mass %, and
Ta: 0.001-0.010, by mass %.

6. The method for producing a grain-oriented electrical steel sheet according to claim 2 , wherein during the decarburization annealing:
during the rapid heating, the entire steel sheet is held at the temperature that is within the range of 250-600° C. for 1-5 seconds, and
the average heating rate of 50° C./s or more does not include the time during which the entire steel sheet is held at the temperature within the range of 250-600° C. for 1-5 seconds.

Assignees

• Jfe Steel Corp

Inventors

• Imamura Takeshi
• Shingaki Yukihiro
• Watanabe Makoto
• Suehiro Ryuichi
• Takamiya Toshito

Classifications

• C22C38/06

  containing aluminium · CPC title

• C21D2201/05

  Grain orientation · CPC title

• C21D8/1261

  following hot rolling · CPC title

• C22C38/04

  containing manganese · CPC title

• C21D8/12 Primary

  during manufacturing of articles with special electromagnetic properties · CPC title