Claims
- 1. In a method for producing a grain-oriented electrical steel sheet having a high magnetic flux density, said method including the steps of:
- providing a silicon steel slab containing from 1.5 to 4.5% Si as well as Al and N;
- hot rolling said slab to provide a hot rolled strip;
- annealing said hot rolled strip;
- cold rolling said hot rolled strip once or twice to produce a cold roll strip having a final sheet thickness;
- decarburization annealing said strip after cold rolling;
- applying an annealing separator to said strip after said decarburization annealing; and thereafter,
- finish annealing said strip to carry out secondary recrystallization and purification;
- the improvement comprising:
- heating said slab prior to hot rolling to a temperature at which incomplete solution of Al and N occurs;
- nitriding said strip after said decarburization annealing and prior to initiation of secondary recrystallization in said finishing annealing step thereby forming precipitates of (Si, Al)N, said precipitates causing said secondary recrystallization.
- 2. A method according to claim 1 wherein the N content of said silicon steel slab is 0.0095% or less.
- 3. A method according to claim 1 further comprising heating said silicon steel slab prior to hot rolling to a temperature of 1270.degree. C. or less.
- 4. A method according to claim 2 further comprising heating said silicon steel slab prior to hot rolling to a temperature of 1270.degree. C. or less.
- 5. A method according to claim 3 further comprising heating said silicon steel slab prior to hot rolling to a temperature of more than 1000.degree. C.
- 6. A method according to claim 4 further comprising heating said silicon steel slab prior to hot rolling to a temperature of more than 1000.degree. C.
- 7. A method according to claim 5 comprising providing said slab with a selected N content and a selected Al content resulting in incomplete solution of Al and N during said heating of said slab at a selected temperature prior to hot rolling.
- 8. A method according to claim 6 comprising providing said slab with a selected N content and a selected Al content resulting in incomplete solution of Al and N during said heating of said slab at a selected temperature prior to hot rolling.
- 9. A method according to claim 1 comprising applying an annealing separator containing MgO and a compound having nitriding ability.
- 10. A method according to claim 1 further comprising:
- annealing said strip in a nitriding atmosphere prior to applying said annealing separator to said strip.
Priority Claims (1)
Number |
Date |
Country |
Kind |
60-179855 |
Aug 1985 |
JPX |
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Parent Case Info
This application is a division, of application Ser. No. 883,962 filed July 10, 1986, now abandoned.
US Referenced Citations (3)
Number |
Name |
Date |
Kind |
3941623 |
Takashina et al. |
Mar 1976 |
|
4171994 |
Miller |
Oct 1979 |
|
4632708 |
Konno et al. |
Dec 1986 |
|
Foreign Referenced Citations (1)
Number |
Date |
Country |
99915 |
Sep 1974 |
JPX |
Divisions (1)
|
Number |
Date |
Country |
Parent |
883962 |
Jul 1986 |
|