Claims
- 1. A method of producing non-oriented electrical steel sheet comprising the steps of:
- preparing a steel slab comprising, by weight, up to 2.5% silicon, up to 1.0% aluminum and up to 2.5% (Si+2Al), with the remainder being iron and unavoidable impurities;
- hot rolling and cold rolling the steel to a final thickness; and
- finish annealing the steel after cold rolling;
- wherein the steel forms a gamma phase by being heated to the gamma region immediately prior to the step of cold rolling to a final thickness, and the average cooling rate from Ar.sub.3 to Ar.sub.1 during cooling transformation (.gamma..fwdarw..alpha.) of the steel is controlled to be 50.degree. C./s or less.
- 2. The method according to claim 1 wherein the steel in the form of a strip, after hot rolling, is coiled at a temperature equal to or higher than the Ar.sub.3 point, and after the strip has been coiled, and is maintained at the gamma region from the Ar.sub.3 point to the Ar.sub.1 point an average cooling rate of 50.degree. C./s or less is used to cool the coil and effect a transformation to the .alpha. phase.
- 3. A method of producing non-oriented electrical steel sheet comprising the steps of:
- preparing a steel melt comprising, by weight, up to 2.5% silicon, up to 1.0% aluminum and up to 2.5% (Si+2Al), with the remainder being iron and unavoidable impurities;
- forming the steel melt into a cast strip by solidification of the steel melt on a moving wall for cooling;
- cold rolling the cast strip to a final thickness; and
- finish annealing the steel after cold rolling;
- wherein the steel forms a gamma phase immediately prior to the step of cold rolling to a final thickness, and a step of cooling from Ar.sub.3 to Ar.sub.1 at an average cooling rate of 50.degree. C./s or less is conducted, with respect to the cast strip formed by solidification of the steel melt on a moving wall for cooling, during the course of .gamma..fwdarw..alpha. cooling transformation of the cast strip.
- 4. A method of producing non-oriented electrical steel sheet comprising the steps of:
- preparing a steel slab comprising, by weight, up to 2.5% silicon, up to 1.0% aluminum and up to 2.5% (Si+2Al), with the remainder being iron and unavoidable impurities;
- hot rolling and cold rolling the steel to a final thickness; and
- finish annealing the steel after cold rolling;
- wherein annealing is conducted prior to the cold rolling to a final thickness, which annealing includes a heat treatment step in which the steel is heated to the .gamma. region and transformed to the .gamma. phase, and then, from the Ar.sub.3 point to the Ar.sub.1 point, an average cooling rate of 50.degree. C./s or less is used to cool the steel and effect a retransformation of the steel to the .alpha. phase.
Priority Claims (3)
Number |
Date |
Country |
Kind |
3-204419 |
Aug 1991 |
JPX |
|
3-204420 |
Aug 1991 |
JPX |
|
3-204421 |
Aug 1991 |
JPX |
|
Parent Case Info
This application is a continuation of now abandoned application, Ser. No. 07/929,516, filed Aug. 14, 1992, now abandoned.
Foreign Referenced Citations (3)
Number |
Date |
Country |
54-76422 |
Jun 1979 |
JPX |
57-198214 |
Dec 1982 |
JPX |
2-182831 |
Jul 1990 |
JPX |
Continuations (1)
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Number |
Date |
Country |
Parent |
929516 |
Aug 1992 |
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