Claims
- 1. A process for the preparation of a high-flux density, grain-oriented electrical steel sheet having a flux density of at least 1.88 T and an especially superior watt loss characteristic, which comprises the steps of:
- heating at 1320.degree. to 1430.degree. C. a slab comprising 0.065 to 0.120% by weight of C, 2.8 to 4.5% by weight of Si, 0.045 to 0.100% by weight of Mn, 0.015 to 0.60% by weight of one or two elements selected from the group consisting of S and Se, 0.0150 to 0.0400% by weight of acid-soluble Al, 0.0060 to 0.0100% by weight of N, 0.03 to 0.25% by weight of Sn and 0.35 to 2.0% by weight of Ni, with the balance being substantially Fe and unavoidable impurities;
- hot rolling the heated slab to form a hot-rolled steel strip;
- cold rolling the hot rolled steel strip once or at least twice with an intermediate annealing, in which a final cold rolling of the steel strip is carried out at a thickness reduction ratio of 83% to 92%;
- annealing the hot rolled steel strip or the cold rolled steel strip at a temperature of from 1030.degree. C. to 1200.degree. C. after the hot rolling and before the final cold rolling, and subsequently, rapidly cooling said annealed steel strip;
- decarburization annealing the final cold rolled steel strip in a wet atmosphere containing hydrogen;
- coating the decarburization annealed steel strip with an annealing separating agent composed mainly of magnesia;
- winding the coated steel strip in the form of a coil;
- finishing annealing the steel strip coil at a high temperature to cause secondary recrystallization;
- removing the annealing separating agent from the finish annealed steel strip;
- level annealing the finish annealed steel strip;
- tension coating the finish annealed steel strip; and
- subjecting the surface of the steel strip to an artificial magnetic domain-controlling treatment in a direction orthogonal to the rolling direction after secondary recrystallization and before or after the tension coating or level annealing.
- 2. A process according to claim 1, wherein the slab further comprises at least one member selected from the group consisting of 0.03 to 0.08% by weight of Cu and 0.005 to 0.035% by weight of Sb.
- 3. A process according to claim 1 or 2, wherein the average grain size of crystal grains of the product in the rolled plane is adjusted to 11 to 50 mm.
Priority Claims (2)
Number |
Date |
Country |
Kind |
63-99328 |
Apr 1988 |
JPX |
|
1-22672 |
Feb 1989 |
JPX |
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Parent Case Info
This application is a division of application Ser. No. 07/340,063 filed Apr. 18, 1989 now abandoned.
US Referenced Citations (7)
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Date |
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0202339 |
Nov 1986 |
EPX |
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DEX |
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FRX |
2571884 |
Apr 1986 |
FRX |
55-18566 |
Feb 1980 |
JPX |
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May 1983 |
JPX |
61-96036 |
May 1986 |
JPX |
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Jun 1986 |
JPX |
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Jun 1986 |
JPX |
62-151511 |
Jul 1987 |
JPX |
848512 |
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GBX |
Non-Patent Literature Citations (2)
Entry |
Patents Abstracts of Japan, vol. 10, No. 56 (C-331) [2113] Mar. 26, 1986. |
European Search Report EP 89 10 7068. |
Divisions (1)
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Number |
Date |
Country |
Parent |
340063 |
Apr 1989 |
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