# US 5,702,541 A · High magnetic density, low iron loss, grain oriented electromagnetic steel sheet and a method for making

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- Number: US 5,702,541 A
- Document ID: US5702541A
- Status: Granted
- Kind: A
- Application number: 08/567,779
- Filed: 1995-12-05
- Granted: 1997-12-30
- Earliest claimed: 1994-12-05
- Assignees: Kawasaki Steel Corporation
- Inventors: Yukio Inokuti
- Web page: https://patentgrep.com/patent/US5702541A

## CPC

- H01F 1/18: with insulating coating
- C21D 8/12: during manufacturing of articles with special electromagnetic properties
- C21D 8/1255: {with diffusion of elements, e.g. decarburising, nitriding}
- C21D 8/1272: {Final recrystallisation annealing}
- C22C 38/02: containing silicon
- H01F 1/14775: {in the form of sheets}
- C21D 3/04: Decarburising
- C21D 8/1233: {Cold rolling}
- H01F: MAGNETS; INDUCTANCES; TRANSFORMERS; SELECTION OF MATERIALS FOR THEIR MAGNETIC PROPERTIES
- C21D: MODIFYING THE PHYSICAL STRUCTURE OF FERROUS METALS; GENERAL DEVICES FOR HEAT TREATMENT OF FERROUS OR NON-FERROUS METALS OR ALLOYS; MAKING METAL MALLEABLE, e.g. BY DECARBURISATION OR TEMPERING (surface treatment of metallic material involving at least one process provided for in class C23 and at least one process covered by this subclass C23F17/00; unidirectional solidification of eutectic materials or unidirectional demixing of eutectoid materials C30B)
- C22C: ALLOYS (treatment of alloys C21D, C22F)

## Abstract

In a grain oriented electromagnetic steel sheet exhibiting high magnetic flux density and low iron loss, having a composition containing about 2.5 to 4.0 weight percent of Si, and about 0.005 to 0.06 weight percent of Al, and i) at least about 95 percent by area ratio of all crystal grains in the electromagnetic steel sheet are large secondary recrystallized grains each having a diameter of about 5 to 50 mm, each having an ›001! axis within about 5.degree. to the rolling direction of the sheet, and each having an ›110! axis within about 5.degree. to the normal direction of the sheet face, and ii) small grains, each having a diameter of about 0.05 to 2 mm, and each having about 2.degree. to 30.degree. of relative angle between the ›001! axis of the small grains and the ›001! axis of the large secondary crystallized grains, the small grains being located in the large secondary crystallized grains or at the grain boundaries. By adding Sb, or Sb and Mo to the steel, magnetic properties further improve.

## Claims

### Claim 1

A grain oriented electromagnetic steel sheet exhibiting excellent magnetic flux density and excellent iron loss, said steel sheet having a rolling direction and a direction normal to said sheet, said steel sheet comprising:
about 2.5 to 4.0 weight percent of Si, and
about 0.005 to 0.06 weight percent of Al; said steel sheet further comprising:
i) large secondary recrystallized grains each having a diameter of about 5 to 50 mm and comprising at least about 95 percent by area ratio of all crystal grains in said electromagnetic steel sheet, said large secondary recrystallized grains defining grain boundaries, said large secondary recrystallized grains each having a ›001! axis and a ›110! axis, said ›001! axis being within about 5.degree. to said rolling direction of said steel sheet and said ›110! axis being within about 5.degree. to said direction normal to said sheet; and
ii) small grains each having a diameter of about 0.05 to 2 mm, said small grains each having a ›001! axis which is at an angle of about 2.degree. to 30.degree. relative to said ›001! axis of said large secondary recrystallized grains, said small grains being positioned in said large secondary recrystallized grains or at said grain boundaries defined by said large secondary recrystallized grains.

### Claim 2 (depends on 1)

A grain oriented electromagnetic steel sheet according to claim 1, further comprising about 0.005 to 0.2 weight percent Sb.

### Claim 3 (depends on 1, 2)

A grain-oriented electromagnetic steel sheet according to any of claims 1-2, wherein said small grains have a crystal orientation defined by angles .alpha., .beta., and .gamma. such that the following relations are satisfied:
.alpha..gtoreq. about 2.degree., .alpha..gtoreq. about 1.5.beta., and .alpha..gtoreq. about 1.5.gamma.,
wherein .alpha. is defined as an angle relative to said rolling direction in a plane parallel to said steel sheet, .beta. is defined as an angle relative to said rolling direction in a plane normal to said steel sheet, and .gamma. is defined as an angle formed in a plane normal to said steel sheet and said plane normal to said steel sheet and being relative to an axis extending normal to said steel sheet and said direction normal to said steel sheet.

### Claim 4

A grain-oriented electromagnetic steel sheet exhibiting excellent magnetic flux density and excellent iron loss, said steel sheet having a rolling direction and a direction normal to said sheet, said steel sheet comprising:
about 2.5 to 4.0 weight percent of Si,
about 0.003 to 0.1 weight percent Mo,
about 0.005 to 0.2 weight percent Sb, and
about 0.005 to 0.06 weight percent of Al; said steel sheet further comprising:
i) large secondary recrystallized grains each having a diameter of about 5 to 50 mm and comprising at least about 95 percent by area ratio of all crystal grains in said electromagnetic steel sheet, said large secondary recrystallized grains defining grain boundaries, said large secondary recrystallized grains each having a ›001! axis and a ›110! axis, said ›001! axis being within about 5.degree. to said rolling direction of said steel sheet and said ›110! axis being within about 5.degree. to said direction normal to said sheet; and
ii) small grains each having a diameter of about 0.05 to 2 mm, said small grains each having a ›001! axis which is at an angle of about 2.degree. to 30.degree. relative to said ›001! axis of said large secondary recrystallized grains, said small grains being positioned in said large secondary recrystallized grains or at said grain boundaries defined by said large secondary recrystallized grains.

### Claim 5 (depends on 4)

A grain-oriented electromagnetic steel sheet according to claim 4, wherein said small grains have a crystal orientation defined by angles .alpha., .beta., and .gamma. such that the following relations are satisfied:
.alpha..gtoreq. about 2.degree., .alpha..gtoreq. about 1.5.beta., and .alpha..gtoreq. about 1.5.gamma.,
wherein .alpha. is defined as an angle relative to said rolling direction in a plane parallel to said steel sheet, .beta. is defined as an angle relative to said rolling direction in a plane normal to said steel sheet, and .gamma. is defined as an angle formed in a plane normal to said steel sheet and said plane normal to said steel sheet and being relative to an axis extending normal to said steel sheet and said direction normal to said steel sheet.