# US 7,608,154 B2 · Nonoriented electrical steel sheet excellent in core loss

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- Number: US 7,608,154 B2
- Document ID: US7608154B2
- Status: Granted
- Kind: B2
- Application number: 11/663,095
- Filed: 2005-09-09
- Published: 2008-05-22
- Granted: 2009-10-27
- Earliest claimed: 2004-09-22
- Assignees: Nippon Steel Corporation
- Inventors: Wataru O-hashi; Masafumi Miyazaki; Yousuke Kurosaki; Takeshi Kubota
- Web page: https://patentgrep.com/patent/US7608154B2

## CPC

- C22C 38/005: {containing rare earths, i.e. Sc, Y, Lanthanides}
- C21D 8/12: during manufacturing of articles with special electromagnetic properties
- C22C 38/02: containing silicon
- C22C 38/04: containing manganese
- C22C 38/06: containing aluminium
- C22C: ALLOYS (treatment of alloys C21D, C22F)
- 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)

## Abstract

A nonoriented electrical steel sheet excellent in core loss comprising copper sulfides with a sphere-equivalent radius of 100 nm or less, wherein the number density of the copper sulfides is less than 1×1010 [inclusions/mm3]. Preferably, the percentage of the number of copper sulfides with a (major axis)/(minor axis) ratio of more than 2 per total number of copper sulfides is 30% or less. The steel preferably further comprises Cu of 0.5 mass % or less and REM of 0.0005% or more and 0.03% or less, wherein the following expression (1) or expressions (1) and (2) are met: [REM]×[Cu]3≧7.5×10−11 (1), ([REM]−0.003)0.1×[Cu]2≦1.25×10−4 (2).

## Claims

### Claim 1

A nonoriented electrical steel sheet comprising:
by mass %,
C: 0.01% or less,
Si: 0.1% or more and 7.0% or less,
Al: 0.005% or more and 3.0% or less,
Mn: 0.1% or more and 2.0% or less,
S: 0.0005% or more and 0.005% or less,
Cu: 0.5% or less and 0.001% or more,
rare earth element (REM): 0.0005% or more and 0.03% or less, and the balance Fe and unavoidable impurities,
wherein the following expression (1) is met,
[REM]×[Cu]3≧7.5×10−11 (1)
where [REM] represents REM mass % and [Cu] represents Cu mass %, and
wherein the number density of copper sulfides having a sphere-equivalent radius of 100 nm or less is 0.4×1010 [inclusion/mm3] or more, and 1×1010 [inclusion/mm3] or less.

### Claim 2

A nonoriented electrical steel sheet comprising:
by mass %,
C: 0.01% or less,
Si: 0.1% or more and 7.0% or less,
Al: 0.005% or more and 3.0% or less,
Mn: 0.1% or more and 2.0% or less,
S: 0.0005% or more and 0.005% or less,
Cu: 0.5% or less and 0.001% or more,
REM: 0.0005% or more and 0.03% or less, and the balance Fe and unavoidable impurities,
wherein, if 0.0005≦[REM]<0.003, the following expression (1) is met,
and, if 0.003≦[REM]≦0.03, the following expressions (1) and (2) are met,
[REM]×[Cu]3≧7.5×10−11 (1)
([REM]−0.003)0.1×[Cu]2≦1.25×10−4 (2),
where [REM] represents REM mass % and [Cu] represents Cu mass %,
wherein the number density of copper sulfides having a sphere-equivalent radius of 100 nm or less is 0.4×1010 [inclusion/mm3] or more, and 1×1010 [inclusion/mm3] or less, and
wherein copper sulfides with a (major axis)/(minor axis) ratio of more than 2 is 30% or less in the copper sulfides having a sphere-equivalent radius of 100 nm or less.