JP2706016B2 - Multi-layer high silicon soft magnetic steel sheet excellent in cold rollability and magnetic properties and method for producing the same - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a high-silicon soft magnetic steel sheet having excellent magnetic properties and used as a soft magnetic material for an iron core of electric equipment, and a method of manufacturing the same.

[0002]

2. Description of the Related Art The addition of Si improves iron loss characteristics.
It is known that since the magnetostriction approaches zero near 5%, the magnetic permeability is further improved and excellent magnetic characteristics are exhibited.
However, when the added amount of Si was 4.5% or more, the cold rolling property was remarkably deteriorated, and it was not practically used.

As a means for improving the cold rolling property, a method for controlling the structure of a hot-rolled sheet has been disclosed (Japanese Patent Application Laid-Open No. 61-1986).
166923, JP-A-62-103321). However, the proposed restriction of the hot rolling conditions not only hinders the productivity but also is not necessarily a good measure in terms of controlling the texture of the product plate.

As another method, a method of improving the cold rolling property by setting the rolling temperature of cold rolling to 350 ° C. to 450 ° C. has been disclosed (Japanese Patent Laid-Open No. 1-200702). There are many problems in terms of surface properties and the like. Further, even if these measures are taken, if the addition amount of Si is 4.5% or more, deformation resistance is high, and it becomes difficult to roll a thin material.

On the other hand, in terms of magnetic characteristics, it is known that a high Si material exhibits particularly excellent magnetic characteristics in a high frequency range.
In this case, the effect is not sufficiently exhibited unless the plate thickness is reduced. Also, it is known that magnetic flux runs intensively near the surface in a high frequency range.

[0006]

SUMMARY OF THE INVENTION An object of the present invention is to provide a steel sheet exhibiting a low iron loss characteristic in a high frequency region while avoiding the problem of cold rolling of a high silicon soft magnetic steel sheet.

[0007]

Means for Solving the Problems The present inventors have conducted research on improving cold rolling properties, and have confirmed that cold rolling properties can be remarkably improved by using a sandwich-structured multi-layer steel sheet as a cold-rolled material. As a result of examining the application of this technology to high-silicon soft magnetic steel sheets, we found a multilayer condition superior to both cold rollability and magnetic properties.

The point is that the weight ratio is C ≦ C.
0.006%, Si: 4.0-7.1%, the material consisting of the balance Fe and unavoidable impurities is used as the surface material,
≦ 0.006%, Si: 0.8-3.5%, and a sandwich-structured cast multi-layered steel sheet containing a material consisting of the balance Fe and unavoidable impurities as an inner layer material, and a surface material / inner material plate It is a multilayered high silicon soft magnetic steel sheet having excellent magnetic properties with a thickness ratio of 0.1 to 0.3.

Furthermore the present invention, the manufactured multilayer billet chemical composition, after hot rolling, while medium-Ri good needs annealing, cold ductility performing cold rolling and final annealing, and excellent magnetic properties by casting This is a method for producing a multi-layer high silicon soft magnetic steel sheet.

Hereinafter, the present invention will be described in detail. First, the reasons for limiting the components will be described. The reason why the C content of the surface layer and the inner layer material is limited to 0.006% or less is that if C is added beyond this , the magnetic properties of the product are significantly deteriorated.

The reason why the amount of Si in the surface layer is limited to the range of 4.0 to 7.1% is that the amount of Si necessary for obtaining low iron loss characteristics in a high frequency region is at least 4.0% or more. Further, an excessive addition of Si has little effect of improving the low iron loss characteristics and remarkably deteriorates the cold rolling property. Therefore, the upper limit is set to 7.1%.

On the other hand, the reason why the amount of Si in the inner layer is limited to the range of 0.8 to 3.5% is that the amount of Si necessary for obtaining excellent magnetic properties is at least 0.8% or more, In view of the above, if the Si content of the inner layer exceeds 3.5%, the deformation resistance increases and thin rolling becomes difficult.

As components other than the above, addition of elements such as Al and Mn which increase electric resistance and reduce iron loss and solid solution C,
The addition of a carbonitride forming element such as Ti or Nb for reducing N does not impair the spirit of the present invention.

Next, the reasons for limiting the multilayer structure will be described. The reason why the thickness ratio of the surface layer material / the inner layer material is limited to the range of 0.1 to 0.3 is that if the thickness ratio is less than 0.1, sufficient low iron loss characteristics cannot be obtained in a high frequency region. The reason why the upper limit is set to 0.3 is that when the ratio of the surface layer material exceeds this , the cold rolling property is remarkably deteriorated and it is difficult to make the product thinner. Here, the sheet thickness ratio is a value obtained by dividing the value obtained by adding the sheet thicknesses of the surface materials on both sides by the sheet thickness of the inner layer material.

The reason why the manufacturing method of the multilayer structure is limited to the casting method is that in other manufacturing methods such as the rolling compression bonding method and the explosion bonding method, breakage occurs at the boundary surface during cold rolling, and the surface layer material is separated. Is likely to occur. In the high frequency range, the magnetic flux concentrates near the surface, so high Si only needs to be the surface material,
According to the present invention, a reduction in alloy cost can be achieved.

[0016]

EXAMPLES Table 1 shows the chemical components of the materials used for the surface layer material and the inner layer material. The test material was multi-layered by casting, solidified, directly hot-rolled, and a 170-mm slab was finish-rolled at about 950 ° C, pickled, and cold-rolled to a plate thickness of 0.23 mm.
Continuous annealing at 00 ° C. for 2 minutes or box annealing at 800 ° C. for 3 hours was performed. In addition, a material partially annealed at 900 ° C. for 2 minutes in a hot rolled sheet was also included in the test material.

Table 2 shows combinations of materials, thickness ratios, experimental conditions, the quality of cold rolling, magnetic properties, and the like.

[Table 1]

[0018]

[Table 2]

Experiment Nos. 1, 2, 3, 7, 10, 11, 1
Nos. 3, 15, 16, and 17 exhibit excellent cold rolling properties and magnetic properties in the range of the steel of the present invention. Experiment No. 4 is the inner layer C
Due to the large amount, deterioration of magnetism is observed. Experiment No. 5 has a large iron loss because the amount of Si in the inner layer is as low as 0.5%. In Experiment No. 6, since the amount of Si in the inner layer was as high as 4.0%, the deformation resistance during cold rolling was high, and not only the workability was poor, but also ear cracks occurred.

In Experiment 8, the amount of Si in the surface layer material was large, and cracks occurred during cold rolling. In Experiment No. 9, excellent magnetic properties could not be obtained due to the high C content of the surface material. In Experiment No. 12, excellent magnetic properties could not be obtained because the ratio of the surface layer material was low. In Experiment No. 14, the ratio of the surface layer material was too high, the deformation resistance during cold rolling increased, and not only the workability was poor, but also cracks occurred.

Experiment No. 18 is a result of a multi-layered steel sheet produced by subjecting a surface layer material and an inner layer material to electron beam welding in a vacuum and then hot-rolling the steel sheet. Cracking occurred during cold rolling. Examination of the magnetism of the portion without cracks revealed that iron loss was uniformly higher than that of the multilayer material of Experiment No. 3 made by casting. The reason why the cast multilayer material exhibits better cold rolling properties and magnetic properties than the pressure-bonded material has not been sufficiently elucidated, but it is presumed that the diffusion phenomenon near the boundary layer is affecting.

Further, the steel of the present invention has a feature that the magnetic flux density is higher than that of a single layer material of high Si steel. For example, the material of the B ₅₀ in Experiment No. 3 is 1.61, B ₅₀ of Experiment No. 1 is a value significantly higher than the 1.50 of comparative material of a single layer material of 1.60 and 6.5% Si .

[0023]

According to the present invention, normal cold rolling can be performed to a very thin plate thickness without damage, and a thin plate having an excellent iron loss value in a high frequency range and a high magnetic flux density can be supplied at low cost. .

Claims (2)

(57) [Claims] 1. A material consisting of C ≦ 0.006% by weight, Si: 4.0 to 7.1%, balance Fe and inevitable impurities as a surface layer material, C ≦ 0.006%, Si: 0.8 to 3.5%, with a sandwiched cast multi-layer steel sheet having a material consisting of the balance Fe and unavoidable impurities as the inner layer material, the thickness ratio of the surface layer material / the inner layer material is 0.1 to 0.3. Multi-layer high silicon soft magnetic steel sheet with excellent cold rollability and magnetic properties. 2. A multi-layered slab is produced by casting.
2. The method for producing a multilayer high silicon soft magnetic steel sheet having excellent cold rollability and magnetic properties according to claim 1, wherein cold rolling and final annealing are performed after or without intermediate annealing .