JP3964964B2 - Method for producing semi-processed non-oriented electrical steel sheet with excellent low magnetic field characteristics B1 - Google Patents

Description

【００２５】
【表２】

【００２６】
実施例に示すように成分元素のＭｎ，Sol.ＡｌとＡｌ₂ Ｏ₃ の比率、並びに結晶粒径とを、本発明範囲に厳密に制御したものは、優れた低磁場磁気特性Ｂ1 が得られた。なお、素材Ｎｏ．３の７２０℃焼鈍材をスキンパス圧延と７５０℃×２時間の磁性焼鈍を施すことなくそのまま測定すると、Ｂ1 は０．２１Ｔと非常に低い値を示した。
【００２７】
［実施例２］
実施例１の素材Ｎｏ．３の熱延板を用い、冷延後の連続焼鈍で結晶粒径を２０μｍにそろえ、絶縁皮膜を塗布乾燥してから、スキンパスの圧下率を調整して、０．５mmの製品となし、７５０℃×２時間の焼鈍をしてから、実施例１と同様に磁性を測定した結果を表３に示す。
【００２８】
【表３】

【００２９】
表３に示すようにスキンパスの圧下率を本発明範囲に制御したものは、優れた磁気特性が得られた。
【００３０】
【発明の効果】
本発明によれば、低磁場特性が優れたセミプロセス無方向性電磁鋼板が得られた。[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a semi-processed non-oriented electrical steel sheet, which is mainly a material for motors for air conditioners and small transformers.
[0002]
[Prior art]
In motors and small transformers, which are electrical devices, the required magnetic characteristics differ depending on the application. In particular, the motor is designed at a low magnetic flux density, that is, around 1.0T (Tesla) or up to 1.5T to reduce iron loss as a core, and even with a small transformer such as a fluorescent lamp, the excitation curve There is a case where the so-called initial permeability, which is a rising edge, is a problem. In recent years, the movement of this low magnetic field design has come out especially in compressor motors for air conditioners.
[0003]
In such a case, annealing is often performed after the core is punched by a customer (electric manufacturer or punching processor). In this case, it is referred to as a semi-processed non-oriented electrical steel sheet because it does not become a final product in the manufacturing process of a steel manufacturer, but becomes a final process by annealing at a customer.
[0004]
The annealing (magnetic annealing) after punching the core is usually about 750 ° C. × 2 hr. The purpose is to reduce the iron loss by coarsening the crystal grain size, and to release the punching distortion to iron. It was to reduce the loss as well as improve the magnetic flux density in the low magnetic field.
[0005]
Conventionally, in order to improve the magnetic flux density of a low magnetic field, it has been considered that it is effective to reduce internal stress, that is, to release punching distortion and the like. However, even if magnetic annealing is performed, the magnetic flux density in a low magnetic field is often not improved so much, and improvement has been demanded. However, the conventional non-oriented electrical steel sheet has been measured and evaluated by the so-called magnetic flux density B50 having a magnetizing force of about 5000 A / m or, at most, the B25 characteristic at 2500 A / m, and having a low value of about B1 or B3. There have been few studies on magnetic field characteristics, and it is today's problem that significant improvement is required simultaneously with basic research.
[0006]
[Problems to be solved by the invention]
In view of the above points, an object of the present invention is to provide a semi-processed non-oriented electrical steel sheet having unprecedented excellent low magnetic field characteristics and a method for producing the same.
[0007]
[Means for Solving the Problems]
To accomplish the above object, in mass%,
C ≦ 0.005%, Si ≦ 2%,
Sol.Al: 0.001 to 0.009%, Mn ≦ 1.0%,
P ≦ 0.1%, S ≦ 0.02%, N ≦ 0.006%,
In the vacuum degassing apparatus in the steelmaking stage where the balance is adjusted to Fe and inevitable impurities , deoxidation is performed with aluminum before desiliconization and after silicon addition, and then the composition ratio of inclusions Al ₂ O ₃ / ( SiO ₂ + Al ₂ O ₃ + MnO) slab adjusted to ≧ 0.2, this slab is hot-rolled and then subjected to hot-rolled sheet annealing or self-annealing without being subjected to hot-rolled sheet annealing, and then cold-rolled and continuously annealed. Then, after the crystal grain size becomes 5 to 70 μm, skin pass rolling is performed at 2 to 15%, and the method for producing an excellent semi-processed non-oriented electrical steel sheet having a low magnetic field characteristic B1 of 0.95 T or more It is.
[0008]
The point of the present invention is three points. In order to improve the magnetic characteristics (B 1) of the low magnetic field, the skin pass process should be effective. Sol.Al amount and Al ₂ O ₃ amount must be controlled in balance with other inclusions. In order to control this amount of Al ₂ O ₃ , it is only necessary to adjust it during the deoxidation process of steelmaking.
[0009]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, the present invention will be described in more detail. First, the reasons for limiting the elements contained will be described.
The amount of C is limited to 0.005% or less. The amount of C is preferably small in terms of magnetic aging, and the upper limit is made 0.005%.
[0010]
The amount of Si is 2% or less. Si is effective in increasing the specific resistance of the steel sheet and reducing the iron loss, but when it increases, the magnetic flux density decreases. Further, since the skin pass material is hard, if the amount of Si is large, the punching die may be damaged. For this reason, the amount of Si shall be 2% or less.
[0011]
The amount of Sol.Al is limited to 0.001 to 0.009%. This is because the low magnetic field characteristics deteriorate when the amount of Sol. Al is outside the range of 0.001 to 0.009%. Further, if it is less than 0.001%, the later-described Al ₂ O ₃ ratio ≧ 0.2 cannot be secured. The amount of Sol.Al means the amount of acid-soluble Al.
[0012]
The amount of Mn is 1.0% or less. Mn increases the specific resistance and simultaneously improves the texture. However, if it increases too much, the low magnetic field characteristics deteriorate, so it must be 1.0% or less.
[0013]
The amount of P is limited to 0.1% or less. P is effective in reducing the slab and burr of the steel sheet in the punching process, but if it is too much, the problem of cracking in the slab occurs, so it is limited to 0.1% or less.
[0014]
The amount of S is limited to 0.02% or less. S is better because it forms fine sulfides such as MnS and Cu _x S (x≈1.6) and degrades iron loss. However, if it exceeds 0.02%, the amount of degradation of magnetism increases. So you must avoid it.
[0015]
N amount is limited to 0.006% or less. If the amount of N increases, blistering due to nitrogen gas called blister is generated on the surface of the steel sheet after annealing, so it is better to reduce the amount, but it must be 0.006% or less for the purpose of preventing this surface defect.
[0016]
The composition ratio of inclusions Al ₂ O ₃ / ( SiO ₂ + Al ₂ O + MnO) is limited to 0.2 or more. The Al ₂ O ₃ ratio greatly affects the low magnetic field characteristics after magnetic annealing, and Al ₂ O ₃ / ( SiO ₂ + Al ₂ O ₃ + MnO) is less than 0.2 because the low magnetic field characteristics deteriorate. Must be avoided. The reason is presumed that the effect of alumina inclusions on the magnetization process in a low magnetic field is dominant, but details are still unknown.
The ratio control of Al ₂ O ₃ is performed at the steel making stage. For example, in vacuum degassing, as a means for reducing free oxygen performed after decarburization, a method of adding Al first before adding Si or Mn and then adding another alloy is effective. In addition, the element addition performed during the vacuum degassing process is usually performed in various forms such as ferrosilicon, ferromanganese, and an aluminum rod.
[0018]
Hot rolling is performed under normal known conditions.
Next, it is generally known that the magnetic flux density is improved by annealing the hot-rolled sheet, but it can be omitted from the viewpoint of production cost.
[0019]
The cold rolling after pickling of the hot-rolled sheet is not particularly limited. As is well known, small-diameter roll rolling by lever rolling provides a slightly higher magnetic flux density, but tandem rolling is advantageous in terms of productivity. There is no need to limit the roll roughness.
[0020]
Subsequently, the crystal grain size after recrystallization by annealing is limited to 5 to 70 μm. This crystal grain size is defined by the average crystal grain size of the cross-sectional structure. The minimum grain size of 5 μm is necessary for satisfying the low magnetic field characteristic B1 , and if it is more than that, there is no problem. Therefore, the upper limit is set to 70 μm. The crystal grain size can be controlled by the annealing temperature and time. However, in this case, care must be taken because the recrystallization temperature and grain growth properties differ depending on the component system. For example, when the amount of Si increases, the recrystallization temperature increases, and when the amount of impurities such as MnO-based inclusions and Ti, Nb increases, the crystal grain growth deteriorates. For this reason, it is generally not possible to specify the temperature × time, but if it is continuous annealing, it is appropriate to hold it in the temperature range of 650 to 1100 ° C. for 1 to 300 seconds. For the management of the crystal grain size, it is preferable to directly observe the optical microscope. For example, the relationship between the iron loss or coercive force and the crystal grain size is examined in advance, and indirectly controlled by the iron loss or coercive force. The method is simple.
[0021]
After the recrystallization annealing of the steel sheet, an insulating film is applied and baked. The insulating film is applied and baked with a known inorganic / organic mixed coating which improves both normal insulation and punchability. If necessary, the insulating film can be a whole surface inorganic or whole surface organic film. The thickness of the insulating film is usually 0.5 to 3 μm. In addition, it is possible to apply and bake this insulating film after skin pass rolling instead of before skin pass. Implementation is simple in terms of cost.
[0022]
Skin pass rolling has a rolling reduction of 2 to 15%. If it is less than 2% or more than 15%, the crystal grain growth by magnetic annealing is not sufficient, and the low magnetic field characteristic B1 is unsatisfactory, so it should be avoided. Moreover, the roll of the skin pass may be performed by either a conventional smooth roll or a dull roll.
[0023]
【Example】
[Example 1]
The components were adjusted to the values shown in Table 1 and dissolved to cast a slab. The Al ₂ O ₃ ratio was controlled by changing the addition timing of Al grains in the vacuum degassing apparatus RH before and after the addition of Fe—Si. Material No. 1-4 and No.1. 7 and 8 were previously deoxidized with Al, and the material No. 5 and 6 were preceded by deoxidation with Si. The slab was heated at 1100 ° C. to obtain a 2.0 mm hot-rolled sheet at a hot rolling finishing temperature of 870 ° C. and a winding temperature of 650 ° C. This hot-rolled sheet is pickled, tandem cold-rolled, subsequently degreased, and then the annealing temperature is adjusted in hydrogen, soaking for 30 seconds is performed in the thickness direction of the thickness of Table 2 An average crystal grain size was obtained. Also, an inorganic / organic mixed insulating film was applied and baked on one side to a thickness of 1 μm. Subsequently, 5% skin pass rolling was performed to obtain a 0.5 mm steel plate. After stamping the Epstein sample, annealing was performed in nitrogen at 750 ° C. for 2 hours, and the magnetic properties of the rolling direction, the width direction, and half were measured, and the results shown in Table 2 were obtained. B1 represents the magnetic flux density at a magnetizing force of 100 A / m.
[0024]
[Table 1]

[0025]
[Table 2]

[0026]
As shown in the examples, when the ratio of the component elements Mn, Sol. Al and Al ₂ O _{3 and} the crystal grain size are strictly controlled within the scope of the present invention, excellent low magnetic field magnetic properties B1 can be obtained. It was. In addition, material No. 3 was measured as it was without subjecting it to skin pass rolling and magnetic annealing at 750 ° C. for 2 hours, B1 was as low as 0.21 T.
[0027]
[Example 2]
The material No. of Example 1 No. 3 hot-rolled sheet, with a continuous annealing after cold rolling, aligning the crystal grain size to 20 μm, applying and drying an insulating film, adjusting the skin pass reduction ratio, and making a 0.5 mm product, 750 Table 3 shows the results of measurement of magnetism in the same manner as in Example 1 after annealing for 2 hours.
[0028]
[Table 3]

[0029]
As shown in Table 3, excellent magnetic properties were obtained when the skin pass reduction rate was controlled within the range of the present invention.
[0030]
【The invention's effect】
According to the present invention, a semi-processed non-oriented electrical steel sheet having excellent low magnetic field characteristics was obtained.

Claims (1)

% By mass
C ≦ 0.005%,
Si ≦ 2%,
SOl.Al: 0.001 to 0.009%,
Mn ≦ 1.0%,
P ≦ 0.1%,
S ≦ 0.02%,
N ≦ 0.006%,
In a vacuum degassing apparatus in the steelmaking stage where the balance is adjusted to Fe and inevitable impurities , deoxidation is performed with aluminum before decarburization and before silicon addition, and then the composition ratio of inclusions Al ₂ O ₃ / A slab adjusted to ( SiO ₂ + Al ₂ O ₃ + MnO) ≧ 0.2, this slab is hot-rolled, and then subjected to hot-rolled sheet annealing or self-annealing without being subjected to hot-rolled sheet annealing. and, since no a continuous annealing 5~70μm crystal grain size, 2-15% of a semi-process non-oriented electrical downfield characteristic B1 which is characterized in that the skin pass rolling is superior over 0.95T A method of manufacturing a steel sheet.