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Nonoriented electromagnetic steel sheet

Inactive Publication Date: 2004-08-05
JFE STEEL CORP
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Benefits of technology

[0013] As described above, high magnetic flux density and low core loss are characteristics that are commonly preferred for all the applications of non-oriented electrical steel sheets, such as various motors and transformers. Among the characteristics, for a non-oriented electrical steel sheet used for reluctance motors, the high magnetic flux density and high dimensional accuracy are particularly important from the point of view of the operating principle.
[0014] However, a non-oriented electrical steel sheet having the following characteristics has not been found: excellent magnetic characteristics such as high magnetic flux density and low core loss, and superior punching properties that is, particularly high dimensional accuracy. In addition to these characteristics, another non-oriented electrical steel sheet further having the following characteristic has also not been found: high strength required for the interior permanent magnet-type DC brushless motor and the like.

Problems solved by technology

However, when the Si content is increased, the core loss is lowered but the magnetic flux density is caused to decrease simultaneously.
However, there is a problem in that the core loss is large.
However, in the grain growth of such low-Si steel, since a decrease in strength arises, shear drop part and burr height of a punched sheet become large at a punching step.
Therefore, there is a problem in that the punching properties such as the dimensional accuracy are significantly lowered.
However, among the above techniques, the technique for improving the punching properties by adding P is focused on reducing the burrs by adjusting the hardness but does not make any consideration for the dimensional accuracy in punching.
Thus, it is conventionally difficult to obtain high strength together with high magnetic flux density.

Method used

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Examples

Experimental program
Comparison scheme
Effect test

example 1

[0202] Each molten steels having the composition shown in Table 1 were experimentally casted. The obtained ingots were hot-rolled into a sheet bar having a thickness of 30 mm. The sheet bar was heated at 1100.degree. C. for 60 minutes and then hot-rolled so as to have a thickness of 2 mm. The hot-rolled sheet was maintained at 600.degree. C. for two hours in a soaking step and was then air cooled, wherein such conditions correspond to coiling conditions. The hot-rolled sheet was annealed at 950.degree. C. for 60 second, pickled, and then cold-rolled (once) so as to have a thickness of 0.50 mm. The cold-rolled sheet was finish-annealed at various temperatures of 700-900.degree. C. to obtain different recrystallized grain diameters. During the cold-rolling step, since many delamination-cracks parallel to a sheet surface were formed in the sample steel J in which P content exceeded invention range, subsequent treatment and the evaluation were not performed.

[0203] The samples No. 56-59 ...

example 2

[0213] Each steel having the composition shown in Table 4, was experimentally casted. Obtained ingot was hot-rolled so as to have a thickness of 2 mm in the same manner as that of Example 1. The hot-rolled sheet was annealed at 1100.degree. C. for 30 seconds, pickled, and then cold-rolled so as to have a thickness of 0.5 mm. The cold-rolled sheet was finish-annealed at various temperatures to obtain different recrystallized grain diameters, wherein the various temperatures are 700.degree. C. or more and are in the single-phase ferrite region.

[0214] Then, samples having a semi-organic insulating coating were prepared in the same manner as that of Example 1. The samples were used in various tests.

[0215] The obtained result is shown in Table 5.

[0216] The steel IDs K-M are such samples that the deoxidization was performed by the Al content and decreasing the Si content. The pair of the steel IDs N and O and the pair of the steel IDs Q and R are samples prepared in order to evaluate the ...

example 3

[0219] The steel ID F having the composition shown in Table 1 and the steel ID N and O having the composition shown in Table 4 were experimentally hot-rolled to have a thickness of 2 mm in the same manner as that of Example 1. Each obtained hot-rolled sheet was annealed at 1100.degree. C. for 30 seconds, pickled, and then cold-rolled so as to have a thickness of 0.50-0.2 mm. The obtained cold-rolled sheet was finish-annealed at various temperatures that is 700.degree. C. or more and is in the single-phase ferrite region to control the recrystallized grain diameter in a range of 35-45 .mu.m.

[0220] Samples having a semi-organic insulating coating were prepared in the same manner as that of Example 1. The samples were used in various tests. For these samples, the core loss at high frequency, that is, at 400 Hz, was measured.

[0221] The obtained result is shown-in Table 6.

6TABLE 6 Punched Punched hole Grain Hole diameter Steel Thickness Diameter B.sub.50 W.sub.15 / 50 W.sub.15 / 400 YP Diame...

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Abstract

The present invention provides a non-oriented electrical steel sheet containing: 0-0.010% of C; at least one of Si and Al in a total amount of 0.03% to 0.5%, or more than 0.5% to 2.5%; 0.5% or less of Mn; 0.10% or more to 0.26% or less of P; 0.015% or less of S; and 0.010% or less of N, on a mass percentage basis, wherein the non-oriented electrical steel sheet has excellent dimensional accuracy during a punching step. When the Si content is low, the non-oriented electrical steel sheet has the excellent balance between high magnetic flux density and low core loss. When the Si content is medium or high, the non-oriented electrical steel sheet has the excellent balance between high magnetic flux density and high strength.

Description

[0001] The present invention relates to non-oriented electrical steel sheets used for iron core materials for electric apparatus. In particular, the present invention relates to a non-oriented electrical steel sheet suitable for an iron core material for reluctance motors, IPM-type DC brushless motors, and the like, and relates to a method for manufacturing the non-oriented electrical steel sheet, wherein the reluctance and DC brushless motors need to have high dimensional accuracy in punching together with high magnetic flux density, and the DC brushless motors further need to have high strength.[0002] The non-oriented electrical steel sheet is of a soft magnetic material mainly used for iron cores of electric apparatus such as motors and transformers. In order to improve the efficiency and in order to miniaturize the electric apparatus, the non-oriented electrical steel sheet needs to have a small core loss and a high magnetic flux density. In the field of electric motors, magneti...

Claims

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Application Information

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IPC IPC(8): C21D8/12C21D9/46C22C38/00C22C38/02C22C38/04C22C38/06C22C38/60H01F1/147H01F1/16
CPCC21D8/12C21D9/46C22C38/002C22C38/004C22C38/008C22C38/02H01F1/14775C22C38/06C22C38/60H01F1/16H01F1/147H01F1/14716C22C38/04C22C38/00
Inventor KOHNO, MASAAKIKAWANO, MASAKIHONDA, ATSUHITOFUJITA, AKIO
Owner JFE STEEL CORP
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