JP4191830B2

JP4191830B2 - Method for producing strain-resistant annealed low iron loss unidirectional electrical steel sheet

Info

Publication number: JP4191830B2
Application number: JP31808698A
Authority: JP
Inventors: 尚茂木; 浩康藤井; 征夫松尾; 公彦杉山
Original assignee: Nippon Steel Corp
Current assignee: Nippon Steel Corp
Priority date: 1998-11-09
Filing date: 1998-11-09
Publication date: 2008-12-03
Anticipated expiration: 2018-11-09
Also published as: JP2000144251A

Description

【０００１】
【発明の属する技術分野】
本発明はトランスの鉄心等に利用される歪取り焼鈍後に鉄損が劣化しない低鉄損一方向性電磁鋼板の製造方法に関するものである。
【０００２】
【従来の技術】
現在実用化されている一方向性電磁鋼板は、鋼板の圧延方向に磁化容易で、主にトランスなどの電気機器に使われている。この鋼板に局所歪の導入、あるいは溝の形成による磁区細分化を施すと、鋼板断面に流れる渦電流が減少し、熱エネルギーの発生が抑えられるため鉄損が低減する。これにより電気機器のエネルギーロスを減らすことができる。
【０００３】
しかしながら上記の磁区細分化効果は、需要家において巻きトランスとして鋼板が組み上げられた後、約８００℃の歪取り焼鈍が行なわれる際に、通常の方法では効果が消失してしまう。
【０００４】
歪取り焼鈍で消えない磁区細分化の方法としては、物理的な溝を形成させる方法が効果的で、例えば特開昭６０−２１１０１２号公報には冷延板に突起付ロールで溝を形成して、二次再結晶を制御する方法が開示され、また特開昭６１−１１７２１８号公報には、仕上焼鈍後の鋼板に適正な荷重および間隔で溝を形成し熱処理することで、微細な結晶粒を周期的に形成する方法が開示されている。
【０００５】
ところで、上記の物理的な溝を形成された一方向性電磁鋼板は、その溝による断面積低下や、溝直下に生じる微細粒のため、透磁率あるいはＢ８（磁界８００Ａ／ｍにおける磁束密度）が劣化することが知られている。磁束密度が高ければ、トランスの設計磁束密度を大きくとることでトランスを小型化できる。従って、従来はより高い設計磁束密度で用いられることを考慮して鋼板の製造も行われてきた。
【０００６】
【発明が解決しようとする課題】
上記のように歪取り焼鈍による鉄損劣下がない耐歪取り焼鈍低鉄損一方向性電磁鋼板には種々の方法が開示されており、溝形成による手法にも様々な製造方法が提案されている。しかしながら、このような製造方法において、簡易な製造条件を用い、使用磁束密度に応じて最適な条件を示している例はなく、工業的に優れているとは必ずしも言えなかった。
【０００７】
本発明では、従来技術よりも簡易な製造条件を用いることで、溝形状、間隔をそれぞれ詳細な一定条件に規定せず、使用磁束密度に応じて最適な製造指針を示す、歪取り焼鈍による鉄損劣化がない耐歪取り焼鈍低鉄損一方向性電磁鋼板の製造方法を提供することにある。
【０００８】
【課題を解決するための手段】
本発明の要旨とするところは、歪取り焼鈍後において優れた低鉄損得性を持ち、使用磁束密度に応じて最適の鉄損が得られる製造指針を示す、歪取り焼鈍による鉄損劣下がない耐歪取り焼鈍低鉄損一方向性電磁鋼板を提供することである。
【０００９】
本発明の具体的な手段は、以下の通りである。
【００１０】
（１）仕上げ焼鈍済みの一方向性電磁鋼板に物理的に溝を形成して磁区細分化を行う鉄損改善方法において、溝形成前後のＢ８劣化を溝深さの調整により０．０３Ｔ〜０．０６Ｔとし、設計磁束密度が１．７Ｔ以上であるトランスに使用することを特徴とする一方向性電磁鋼板の鉄損改善方法。
【００１１】
（２）仕上げ焼鈍済みの一方向性電磁鋼板に物理的に溝を形成して磁区細分化を行う鉄損改善方法において、溝形成前後のＢ８劣化を溝深さの調整により０．０４Ｔ〜０．０６Ｔとし、設計磁束密度が１．７Ｔ未満、１．４Ｔ以上であるトランスに使用することを特徴とする一方向性電磁鋼板の鉄損改善方法。
【００１２】
（３）仕上げ焼鈍済みの一方向性電磁鋼板に物理的に溝を形成して磁区細分化を行う鉄損改善方法において、溝形成前後のＢ８劣化を溝深さの調整により０．０５Ｔ〜０．０９Ｔとし、設計磁束密度が１．４Ｔ未満であるトランスに使用することを特徴とする一方向性電磁鋼板の鉄損改善方法。
【００１３】
【発明の実施の形態】
以下、実験結果を基に詳細に説明する。
【００１４】
本発明者らは鋼板表面に形成される溝の幅、深さ、間隔、溝直下に形成される微細粒と歪取り焼鈍後の鉄損特性を種々検討した結果、磁区細分化後のＢ８劣化量と鉄損の間にある一定の関係があることを見出した。以下、実験結果に基づいて詳細に説明する。
【００１５】
仕上げ燒鈍済みの板厚０．２３ｍｍの一方向性電磁鋼板で、Ｂ８がほぼ１．９３Ｔのものを選定し、これに圧延方向に対して垂直方向に刃型をプレスして、溝の間隔および深さを種々変えたサンプルを作成した。
【００１６】
この鋼板を最後に８００℃で歪取り焼鈍を行った後、主な設計磁束密度として用いられているＢ＝１．３、１．５、１．７Ｔの条件で鉄損を評価した。
【００１７】
図１に、Ｂ８とＢ＝１．３Ｔの鉄損（Ｗ１３／５０）の関係を示す。この磁束密度域（１．４Ｔ＞Ｂ）では、Ｂ８が１．８４〜１．８８、従って溝形成前後のＢ８劣化量が０．０５Ｔ〜０．０９Ｔで鉄損の最適値が得られた。
【００１８】
図２に、Ｂ８とＢ＝１．５Ｔの鉄損（Ｗ１５／５０）の関係を示す。この磁束密度域（１．７Ｔ＞Ｂ≧１．４Ｔ）では、Ｂ８が１．８７〜１．８９、従って溝形成前後のＢ８劣化が０．０４Ｔ〜０．０６Ｔで鉄損の最適値が得られた。
【００１９】
図３に、Ｂ８とＢ＝１．７Ｔの鉄損（Ｗ１７／５０）の関係を示す。この磁束密度域（Ｂ≧１．７Ｔ）では、Ｂ８が１．８７〜１．９０、従って溝形成前後のＢ８劣化量が０．０３Ｔ−０．０６Ｔで鉄損の最適値が得られた。
【００２０】
また表１に、それぞれの溝間隔および溝深さにおけるＢ８劣化量を示す。表１からＢ８劣化量は溝間隔に関わらず溝深さとともに漸増しており、このことから溝深さによって所望のＢ８劣化量を制御できることが明らかになった。従って、前記Ｂ８劣化を調整する方法としては、溝の深さを調整すること、好ましくは５〜２５μｍの範囲で使用するトランスの設計磁束密度に応じて溝の深さを調整する必要がある。
【００２１】
【表１】

本発明によりＢ８劣化量を規定することで低鉄損条件が得られるメカニズムは必ずしも定かではないが、以下のように考えている。溝形成によって磁区細分化が生じ鉄損が低減する。一方、Ｂ８劣化量が大きすぎると鋼板透磁率が減少して実質的な断面積減少となり、相対的に通過磁束が大きくなって鉄損を増加させる。この２つの相反する現象の兼ね合いによって最適値が現われ、ある一定の最適Ｂ８劣化量が決定されるためと考えている。
【００２２】
上記知見により、歪取り焼鈍後も優れた低鉄損得性を持ち、使用磁束密度に応じて最適の鉄損が得られる製造指針を有する、歪取り焼鈍による鉄損劣下がない耐歪取り焼鈍低鉄損一方向性電磁鋼板の製造方法が明らかになった。
【００２３】
以下、実施例を説明する。
【００２４】
【実施例】
仕上げ燒鈍済みの板厚０．２３ｍｍの一方向性電磁鋼板に、その圧延方向に対して垂直に鋭いケガキ針を走らせ、溝の間隔、深さを種々変えた溝を形成した。最後に８００℃で歪取り焼鈍を行い、鉄損を評価した。結果を表２に示す。
【００２５】
【表２】

【００２６】
【発明の効果】
以上説明したように、本発明に記載されたＢ８劣化量を指針として溝を形成することにより、一方向性電磁鋼板の歪取り焼鈍処理後の鉄損特性を、従来のものより使用磁束密度に応じて最適の鉄損が得られることができ、トランスのエネルギー損失の観点から、その工業的意義は極めて大である。
【図面の簡単な説明】
【図１】Ｂ＝１．３Ｔにおける溝形成後のＢ８と各磁束密度における鉄損の関係を示す図。
【図２】Ｂ＝１．５Ｔにおける溝形成後のＢ８と各磁束密度における鉄損の関係を示す図。
【図３】Ｂ＝１．７Ｔにおける溝形成後のＢ８と各磁束密度における鉄損の関係を示す図。[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a method for producing a low iron loss unidirectional electrical steel sheet in which iron loss does not deteriorate after stress relief annealing used for a transformer core or the like.
[0002]
[Prior art]
Unidirectional electrical steel sheets that are currently in practical use are easily magnetized in the rolling direction of the steel sheet and are mainly used in electrical equipment such as transformers. When this steel sheet is subjected to the introduction of local strain or magnetic domain refinement by the formation of grooves, eddy currents flowing in the cross section of the steel sheet are reduced, and generation of thermal energy is suppressed, so that iron loss is reduced. Thereby, the energy loss of an electric equipment can be reduced.
[0003]
However, the above-mentioned effect of subdividing the magnetic domain disappears in a normal method when a stress relief annealing at about 800 ° C. is performed after a steel plate is assembled as a winding transformer by a customer.
[0004]
As a method of subdividing magnetic domains that does not disappear by strain relief annealing, a method of forming physical grooves is effective. For example, in Japanese Patent Application Laid-Open No. 60-2111012, grooves are formed on a cold-rolled plate by a roll with a protrusion. In addition, a method for controlling secondary recrystallization is disclosed, and Japanese Patent Application Laid-Open No. 61-117218 discloses a method for forming fine crystals by forming grooves at an appropriate load and interval in a steel sheet after finish annealing and performing heat treatment. A method for periodically forming grains is disclosed.
[0005]
By the way, the unidirectional electrical steel sheet in which the above-mentioned physical grooves are formed has a permeability or B8 (magnetic flux density at a magnetic field of 800 A / m) because of a reduction in cross-sectional area due to the grooves and fine grains generated just below the grooves. It is known to deteriorate. If the magnetic flux density is high, the transformer can be reduced in size by increasing the designed magnetic flux density of the transformer. Therefore, steel sheets have been manufactured in consideration of the fact that they are used at a higher design magnetic flux density.
[0006]
[Problems to be solved by the invention]
As described above, various methods have been disclosed for anti-strain-free annealed low iron loss unidirectional electrical steel sheets that do not cause deterioration of iron loss due to strain-relief annealing, and various manufacturing methods have been proposed for the groove-forming method. ing. However, in such a manufacturing method, there is no example showing the optimum conditions according to the magnetic flux density used, using simple manufacturing conditions, and it cannot always be said that it is industrially excellent.
[0007]
In the present invention, by using simpler manufacturing conditions than in the prior art, the groove shape and spacing are not defined as detailed constant conditions, and the optimum manufacturing guidelines according to the magnetic flux density used are shown. An object of the present invention is to provide a method for producing a strain relief annealed low iron loss unidirectional electrical steel sheet without deterioration of loss.
[0008]
[Means for Solving the Problems]
The gist of the present invention is that the iron loss is inferior due to the strain relief annealing, which shows the production guidelines that have an excellent low iron loss ability after the stress relief annealing and obtain the optimum iron loss according to the magnetic flux density used. There is no strain relief annealing low iron loss unidirectional electrical steel sheet.
[0009]
Specific means of the present invention are as follows.
[0010]
(1) to the finish annealing has been grain-oriented electrical steel sheet to form a physically groove in iron loss improvement method of performing magnetic domain refining, the B8 degradation before and after the groove formation by adjusting the groove depth 0.03T~0 A method for improving the iron loss of a unidirectional electrical steel sheet, characterized by being used in a transformer having a design magnetic flux density of 1.7 T or more .
[0011]
(2) In the iron loss improvement method in which grooves are physically formed on a unidirectional electrical steel sheet that has been subjected to finish annealing to subdivide the magnetic domain , B8 deterioration before and after the groove formation is adjusted to 0.04 T to 0 by adjusting the groove depth. A method for improving the iron loss of a unidirectional electrical steel sheet, characterized by being used in a transformer having a design magnetic flux density of less than 1.7T and 1.4T or more .
[0012]
(3) In the iron loss improving method in which grooves are physically formed in a unidirectional electrical steel sheet that has been subjected to finish annealing to subdivide the magnetic domain , B8 deterioration before and after the groove formation is adjusted to 0.05 T to 0 by adjusting the groove depth. 0.09T, and a method for improving the iron loss of a unidirectional electrical steel sheet, which is used for a transformer having a designed magnetic flux density of less than 1.4T .
[0013]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, it demonstrates in detail based on an experimental result.
[0014]
As a result of various investigations on the width, depth, spacing, fine grains formed immediately below the grooves, and iron loss characteristics after strain relief annealing, the present inventors have found that B8 degradation after magnetic domain refinement We found a certain relationship between quantity and iron loss. Hereinafter, it demonstrates in detail based on an experimental result.
[0015]
A unidirectional electrical steel sheet with a finish thickness of 0.23 mm and a B8 value of approximately 1.93T is selected. Samples with different depths were prepared.
[0016]
The steel sheet was finally subjected to strain relief annealing at 800 ° C., and then the iron loss was evaluated under the conditions of B = 1.3, 1.5, and 1.7T used as main design magnetic flux densities.
[0017]
FIG. 1 shows the relationship between B8 and the iron loss (W13 / 50) of B = 1.3T. In this magnetic flux density region (1.4T> B), B8 was 1.84 to 1.88, and therefore the B8 deterioration amount before and after groove formation was 0.05T to 0.09T, and the optimum value of iron loss was obtained.
[0018]
FIG. 2 shows the relationship between B8 and B = 1.5T iron loss (W15 / 50). In this magnetic flux density range (1.7T> B ≧ 1.4T), B8 is 1.87 to 1.89, and therefore the B8 deterioration before and after groove formation is 0.04T to 0.06T, and the optimum value of iron loss is obtained. It was.
[0019]
FIG. 3 shows the relationship between iron loss (W17 / 50) of B8 and B = 1.7T. In this magnetic flux density region (B ≧ 1.7T), B8 was 1.87 to 1.90, and therefore the B8 deterioration amount before and after the groove formation was 0.03T−0.06T, and the optimum value of iron loss was obtained.
[0020]
Table 1 shows the amount of B8 deterioration at each groove interval and groove depth. From Table 1, the B8 deterioration amount gradually increased with the groove depth regardless of the groove interval, and it was clarified that the desired B8 deterioration amount can be controlled by the groove depth. Therefore, as a method for adjusting the B8 deterioration, it is necessary to adjust the depth of the groove, preferably according to the design magnetic flux density of the transformer used in the range of 5 to 25 μm.
[0021]
[Table 1]

The mechanism by which the low iron loss condition is obtained by specifying the B8 deterioration amount according to the present invention is not necessarily clear, but is considered as follows. Groove formation causes magnetic domain fragmentation and iron loss is reduced. On the other hand, if the amount of B8 deterioration is too large, the magnetic permeability of the steel sheet decreases and the cross-sectional area decreases substantially, the passing magnetic flux increases relatively, and the iron loss increases. This is because the optimum value appears due to the balance between the two conflicting phenomena, and a certain optimum amount of B8 deterioration is determined.
[0022]
Based on the above knowledge, it has excellent low iron loss ability even after strain relief annealing, and has a manufacturing guideline that can obtain the optimum iron loss according to the magnetic flux density used. The production method of low iron loss unidirectional electrical steel sheet has been clarified.
[0023]
Examples will be described below.
[0024]
【Example】
A sharp marking needle was run perpendicularly to the rolling direction on a unidirectional electrical steel sheet having a thickness of 0.23 mm that had been subjected to finish annealing to form grooves having various groove intervals and depths. Finally, strain relief annealing was performed at 800 ° C. to evaluate iron loss. The results are shown in Table 2.
[0025]
[Table 2]

[0026]
【The invention's effect】
As described above, by forming a groove using the B8 deterioration amount described in the present invention as a guideline, the iron loss characteristic after the strain relief annealing of the unidirectional electrical steel sheet is changed to the magnetic flux density used than the conventional one. Accordingly, the optimum iron loss can be obtained, and its industrial significance is extremely large from the viewpoint of energy loss of the transformer.
[Brief description of the drawings]
FIG. 1 is a diagram showing a relationship between B8 after groove formation at B = 1.3T and iron loss at each magnetic flux density.
FIG. 2 is a diagram showing a relationship between B8 after groove formation at B = 1.5T and iron loss at each magnetic flux density.
FIG. 3 is a diagram showing a relationship between B8 after groove formation at B = 1.7T and iron loss at each magnetic flux density.

Claims

In the iron loss improvement method in which grooves are physically formed in a unidirectional electrical steel sheet that has been subjected to finish annealing to subdivide the magnetic domain , B8 deterioration before and after the groove formation is adjusted to 0.03T to 0.06T by adjusting the groove depth. A method for improving the iron loss of a unidirectional electrical steel sheet, characterized by being used for a transformer having a designed magnetic flux density of 1.7 T or more .

In the iron loss improvement method in which grooves are physically formed in a unidirectional electrical steel sheet that has been subjected to finish annealing to subdivide the magnetic domain , B8 deterioration before and after the groove formation is adjusted to 0.04T to 0.06T by adjusting the groove depth. A method for improving the iron loss of a unidirectional electrical steel sheet, characterized by being used for a transformer having a designed magnetic flux density of less than 1.7T and 1.4T or more .

In the iron loss improvement method in which grooves are physically formed in a unidirectional electrical steel sheet that has been subjected to finish annealing to subdivide the magnetic domain , B8 deterioration before and after groove formation is adjusted to 0.05T to 0.09T by adjusting the groove depth. A method for improving the iron loss of a unidirectional electrical steel sheet, characterized by being used for a transformer having a designed magnetic flux density of less than 1.4T .