(19) |
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(11) |
EP 0 947 597 A3 |
(12) |
EUROPEAN PATENT APPLICATION |
(88) |
Date of publication A3: |
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31.01.2001 Bulletin 2001/05 |
(43) |
Date of publication A2: |
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06.10.1999 Bulletin 1999/40 |
(22) |
Date of filing: 23.03.1999 |
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(84) |
Designated Contracting States: |
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AT BE CH CY DE DK ES FI FR GB GR IE IT LI LU MC NL PT SE |
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Designated Extension States: |
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AL LT LV MK RO SI |
(30) |
Priority: |
30.03.1998 JP 8400798 28.10.1998 JP 30750798
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(71) |
Applicant: NIPPON STEEL CORPORATION |
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Chiyoda-ku Tokyo-to (JP) |
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(72) |
Inventors: |
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- Kumano, Tomoji, c/oNIPPON STEEL CORP. YAWATA WORKS
Kitakyushu City, Fukuoka (JP)
- Fujii, Norikazu, c/oNIPPON STEEL CORP YAWATA WORK
Kitakyushu City, Fukuoka (JP)
- Kuroki, Katsuro, c/o NITTETSU PLANT DESIGNING CORP
Kitakyushu City, Fukuoka (JP)
- Yamasaki, Koji, c/oNIPPON STEEL CORP. YAWATA WORKS
Kitakyushu City, Fukuoka (JP)
- Ohata, Yoshifumi, NIPPON STEEL CORP. YAWATA WORK
Kitakyushu City, Fukuoka (JP)
- Mogi, Hisashi, c/o NIPPON STEEL CORP. YAWATA WORKS
Kitakyushu City, Fukuoka (JP)
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(74) |
Representative: VOSSIUS & PARTNER |
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Siebertstrasse 4 81675 München 81675 München (DE) |
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(54) |
Method of producing a grain-oriented electrical steel sheet excellent in magnetic
characteristics |
(57) A method for producing a grain-oriented electrical steel sheet excellent in magnetic
characteristics is provided wherein differentiated use of primary and secondary inhibitors
enables production without high temperature slab heating, few glass film defects and
no lack of uniformity in secondary recrystallization.
A slab containing 0.025 ∼ 0.10% of C, 2.5 ∼ 4.0% of Si as well as acid-soluble Al,
Mn, Cu, N, and Seq = (S + 0.406 Se) of 0.008 ∼ 0.05% is reheated to a temperature
of more than 1050°C and lower than 1350°C and hot-rolled into a hot-rolled strip.
The hot-rolled strip is optionally annealed, subjected to at least one cold rolling
with intermediate annealing, whereafter the sheet is decarburization annealed to have
primary recrystallization grains after completion of the decarburization annealing
of an average diameter of not less than 7 µm and less than 18 µm, nitrided up to the
start of secondary recrystallization, coated with an annealing separator composed
mainly of MgO, and subjected to final finish annealing.