Non-oriented electrical steel sheet and method for producing the same
AssigneeJfe Steel Corporation
InventorsTomoyuki OKUBO, Kuni YAMADA, Takaaki TANAKA, Yusuke SHIMOYAMA
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Abstract
A non-oriented electrical steel sheet as a steel material from which both a rotor core material having excellent fatigue properties and a stator core material having excellent magnetic properties after core annealing is performed can be obtained. The steel sheet is produced by hot-rolling a steel material including predetermined amounts of C, Si, Mn, and Al, followed by hot-band annealing, cold rolling, and cold-band annealing.
Claims8
A non-oriented electrical steel sheet having an ingredient composition comprising C:
- 0.0005 to 0.0050 mass %, Si:
- 1.0 to 5.0 mass %, Mn:
- 0.05 to 5.0 mass %, P:
- 0 to 0.1 mass %, S:
- 0 to 0.010 mass %, Al:
- 0.005 to 3.0 mass %, and N:
- 0 to 0.010 mass % with a balance being Fe and unavoidable impurities,
- characterized in that
- D1 is 75 μm or less and that
- D1 to D3 satisfy the following Expressions (1) and (2):
- D
-
- 2
- /
- D
-
- 1
- ≥
- 1
- .02
- (
- 1
- )
- D
-
- 3
- /
- D
-
- 1
- ≥
- 0.6
- ,
- (
- 2
- )
- wherein
- D1 represents an average crystal grain size of crystal grains with all orientations, D2 represents an average crystal grain size of crystal grains with an orientation {411}<148>, and D3 represents an average crystal grain size of crystal grains with an orientation {211}<011>, each measured by electron backscatter diffraction.
A method for producing a non-oriented electrical steel sheet, comprising:
- hot rolling a steel slab having an ingredient composition comprising C:
- 0.0005 to 0.0050 mass %, Si:
- 1.0 to 5.0 mass %, Mn:
- 0.05 to 5.0 mass %, P:
- 0 to 0.1 mass %, S:
- 0 to 0.010 mass %, Al:
- 0.005 to 3.0 mass %, and N:
- 0 to 0.010 mass %, with a balance being Fe and unavoidable impurities;
- performing hot-band annealing;
- performing cold rolling once or cold rollings with intermediate annealing interposed between each cold rolling twice or more to obtain a cold-rolled sheet with a final thickness;
- and
- subjecting the cold-rolled sheet to cold-band annealing,
- characterized in that
- the steel sheet before the cold rolling to obtain the final thickness is subjected to heat treatment by cooling the steel sheet to 90° C. or below, aging the steel sheet at a temperature of 100 to 300° C., and then cooling the steel sheet again,
- that the first pass of the cold rolling to obtain the final thickness is conducted at a bite temperature of 70° C. or below, using a work roll having a surface roughness Ra of 0.05 to 3.0 μm, and
- that the soaking temperature of the cold-band annealing is set in the range of 700 to 950° C.
Dependencies are inferred from the claim text.