JP2008285721A - Nonoriented silicon steel sheet having excellent blanking workability and core loss, and method for producing the same - Google Patents
Nonoriented silicon steel sheet having excellent blanking workability and core loss, and method for producing the same Download PDFInfo
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本発明は、打ち抜き加工等により所定の形状に加工された後にモーターやトランスの鉄芯などに用いられ、磁気特性に優れ、かつ打ち抜き性が良好な無方向性電磁鋼板を提供することを目的とする。 An object of the present invention is to provide a non-oriented electrical steel sheet that is used for an iron core of a motor or a transformer after being processed into a predetermined shape by punching or the like and has excellent magnetic properties and good punchability. To do.
無方向性電磁鋼板は需要家で所定の鉄芯形状に合わせて打ち抜き加工を施され使用される。その際、打ち抜き破面の周辺に加工歪が残留し磁気特性が劣化する場合が多い。この対策として、Ｓｉ量やＡｌ量を多くして要求される製品特性より高いグレードの高級鋼板を適用するか、あるいは打ち抜き加工後に焼鈍を施して歪を除去することが一般的に行われている。しかしいずれの場合も、所用合金量の増加や工程増加などによるコストアップが避けられない。 Non-oriented electrical steel sheets are used after being stamped by a customer in accordance with a predetermined iron core shape. At that time, there are many cases where machining strain remains around the punched fracture surface and the magnetic characteristics are deteriorated. As a countermeasure, it is common practice to apply high grade steel sheets with higher grades than required product characteristics by increasing the amount of Si or Al, or to remove strain by annealing after punching. . However, in either case, an increase in cost due to an increase in the amount of alloys required and an increase in processes is inevitable.
また、打ち抜き加工は通常、連続的に打ち抜かれるが、打ち抜き回数を重ねるにつれ工具の端面が磨耗し、さらに打ち抜き回数を重ねると鋼板の打ち抜き端面にダレが生じて、製品の積み精度が悪化する問題が生じることがある。 In addition, punching is usually performed continuously, but as the number of punches is repeated, the end face of the tool wears. May occur.
以上を鑑みると、打ち抜き性が良く、かつ磁気特性が良好な打ち抜き製品を得るためには、打ち抜き加工時に鋼板がより破断し易いこと、すなわちより軽い荷重かつより短いストロークで打ち抜けることが好ましい。この特性をこれ以降、打ち抜き性が良いと称する。 In view of the above, in order to obtain a punched product having good punchability and good magnetic properties, it is preferable that the steel sheet is more likely to break during punching, that is, punching with a lighter load and a shorter stroke. This characteristic is hereinafter referred to as good punchability.
打ち抜き性を改善するための方法として、鋼板の成分や金属組織を調整して鋼板の硬度を調整するなど種々の方法が開示されているが、別法として、鋼板内部の介在物を活用する技術が開示されている。 Various methods have been disclosed as methods for improving punchability, such as adjusting the steel sheet's composition and metal structure to adjust the hardness of the steel plate. Is disclosed.
例えば、（特許文献１）、（特許文献２）、などに開示されるように、鋼中のＣを質量％で０．１％から１．０％と通常使用される電磁鋼板より高くし、鋼中に粗大なグラファイトを析出させ、粗大グラファイトのせん断滑りにより鋼板のせん断抵抗を減少させ、鋼板の塑性変形領域を減少させ、打ち抜き後の磁気特性の劣化を抑制する方法が知られている。 For example, as disclosed in (Patent Document 1), (Patent Document 2), etc., C in the steel is 0.1% to 1.0% in mass% higher than the electromagnetic steel sheet normally used, There is known a method in which coarse graphite is precipitated in steel, the shear resistance of the steel sheet is reduced by shear sliding of the coarse graphite, the plastic deformation region of the steel sheet is reduced, and the deterioration of magnetic properties after punching is suppressed.
また、（特許文献３）、（特許文献４）、などに開示されるように、鋼の成分ならびに熱処理の温度履歴を調整することにより鋼中のＭｎＳを粗大化させ、粗大ＭｎＳのせん断滑りによる潤滑効果を利用して鋼板のせん断抵抗を減少させ、鋼板の塑性変形領域を減少させ、打ち抜き後の磁気特性の劣化を抑制する方法が知られている。 Further, as disclosed in (Patent Document 3), (Patent Document 4), etc., MnS in the steel is coarsened by adjusting the steel components and the temperature history of the heat treatment, and due to shear sliding of the coarse MnS. A method is known in which the lubrication effect is used to reduce the shear resistance of a steel sheet, reduce the plastic deformation region of the steel sheet, and suppress the deterioration of magnetic properties after punching.
さらにまた、（特許文献５）などに開示されるように、比較的稠密な介在物の間隙に割れが伝播し易いことを活用して、鋼板の内部に割れの起点かつ伝播点となるよう列状に並んだ介在物を与えて打ち抜き加工時の割れを促進し、鋼板の塑性変形領域を減少させ、打ち抜き後の磁気特性の劣化を抑制する方法が知られている。 Furthermore, as disclosed in (Patent Document 5) and the like, by utilizing the fact that cracks easily propagate in the gaps of relatively dense inclusions, it is arranged so that cracks start and propagate in the interior of the steel sheet. There is known a method of providing inclusions arranged in a shape to promote cracking during punching, reduce the plastic deformation region of the steel sheet, and suppress deterioration of magnetic properties after punching.
打ち抜き性を改善するため、例えばＡｌ含有量を下げＳｉ含有量を上げて固有抵抗を保ちつつ鋼板の硬度を調整する、あるいはＭｎやＰなどを添加して鋼板の硬度を上げるなどの、鋼板の成分を変更する方法によると、所定の打ち抜き性と磁気特性を得るための合金添加量が増えてコスト高になるという問題がある。 In order to improve punchability, for example, by adjusting the hardness of the steel sheet while reducing the Al content and increasing the Si content while maintaining the specific resistance, or by adding Mn or P to increase the hardness of the steel sheet, According to the method of changing the components, there is a problem that the amount of alloy addition for obtaining predetermined punchability and magnetic characteristics increases, resulting in high cost.
また、鋼板の結晶粒径を細かくして打ち抜き加工時の割れの伝播を促進し破断し易くする方法によると、結晶粒径が細かいことにより鉄損が増加して磁気特性が劣位となり、あるいは打ち抜き加工後の焼鈍を充分に行って結晶粒を成長させなければならず、工程が煩雑となりコスト高となる。 In addition, according to the method of reducing the crystal grain size of the steel sheet and promoting the propagation of cracks during punching and making it easy to break, the fine grain size increases the iron loss, resulting in inferior magnetic properties, or punching. The post-processing annealing must be sufficiently performed to grow the crystal grains, which complicates the process and increases the cost.
一方、鋼板内部の介在物を活用して打ち抜き性を改善する技術によると、上記の問題を回避することができる。しかし上記に開示された方法によると、以下に述べる問題が発生する場合がある。 On the other hand, according to the technique for improving the punchability by utilizing the inclusions inside the steel plate, the above problem can be avoided. However, according to the method disclosed above, the following problems may occur.
鋼中のＣ含有量を高めて粗大なグラファイトを析出させ、それを活用する場合、鋼中のＣが全て粗大グラファイトの形成に消費されず、フリーＣが鋼中に残留し、鋼板の焼鈍段階において鋼中に不可避的に存在する不純物元素と反応し、例えばＴｉＣなどの低温析出物を形成する場合がある。低温析出物はそれ自体の析出温度が低温なため成長せず、鋼中に微細に分散析出し、焼鈍段階での鋼板結晶粒の成長を阻害し、磁気特性が劣化する場合がある。 When precipitation of coarse graphite by increasing the C content in steel and utilizing it, all of the C in the steel is not consumed for the formation of coarse graphite, free C remains in the steel, and the annealing stage of the steel sheet May react with impurity elements inevitably present in the steel to form, for example, low-temperature precipitates such as TiC. The low-temperature precipitates do not grow because their own precipitation temperature is low, and they are finely dispersed and precipitated in the steel, obstructing the growth of crystal grains in the annealing stage, and may deteriorate the magnetic properties.
また、鋼中に粗大なＭｎＳを形成させて活用する場合、ＭｎＳの粗大化のためＳを充分高める必要があるが、鋼中のＳが全て粗大ＭｎＳの形成に消費されず、フリーＳが鋼中に残留し、これによって鋼板の焼鈍段階において微細なＭｎＳが析出し、焼鈍段階での鋼板結晶粒の成長を阻害し、磁気特性が劣化する場合がある。 Moreover, when forming and utilizing coarse MnS in steel, it is necessary to sufficiently increase S for coarsening of MnS. However, all S in steel is not consumed for formation of coarse MnS, and free S is steel. In this case, fine MnS precipitates in the annealing stage of the steel sheet, which may inhibit the growth of crystal grains in the annealing stage and deteriorate the magnetic properties.
また、列状に並んだ介在物により打ち抜き加工時の割れを促進する場合、鋼板の圧延により介在物を圧延方向に延伸させ破断させて介在物を列状とすることが通常であるが、圧延方向に列状に並んだ介在物は鋼板の板厚方向の結晶粒成長を阻害するばかりでなく、板厚方向の磁壁移動の障害となり透磁率が低下して磁気特性が劣化するため好ましくない。さらに、打ち抜き時に圧延方向に列状に並んだ介在物に沿って割れが伝播すると、本来は板厚方向に貫通すべき割れが圧延方向に伝播することとなり、打ち抜き後の寸法精度が低下するという問題が生じる。 Also, when promoting cracks during punching by inclusions arranged in a row, it is normal to roll the inclusions in the rolling direction by rolling the steel sheet to break the inclusions into rows, Inclusions arranged in a row in the direction are not preferable because they not only inhibit the growth of crystal grains in the plate thickness direction of the steel plate, but also hinder magnetic domain wall movement in the plate thickness direction and lower the magnetic permeability and deteriorate the magnetic properties. Furthermore, if cracks propagate along the inclusions arranged in a line in the rolling direction during punching, the cracks that should originally penetrate in the plate thickness direction propagate in the rolling direction, and the dimensional accuracy after punching decreases. Problems arise.
本発明は、アルミナやシリカのような硬質の酸化物介在物（以下、介在物と称する）を、結晶粒成長や磁壁移動の障害とならないように径と密度を所定の範囲に調整して鋼板内部に分散させることで、打ち抜き加工時の割れ発生の起点として作用させ、打ち抜き性を向上させつつ、破面周辺の母材への加工歪の蓄積を最小化して鋼板の磁気特性の劣化を抑制し、打ち抜き後の焼鈍を簡省略化して磁気特性を良好化することが可能な無方向性電磁鋼板を提供することを目的とする。 The present invention relates to a steel plate in which hard oxide inclusions such as alumina and silica (hereinafter referred to as inclusions) are adjusted in diameter and density within a predetermined range so as not to hinder crystal grain growth and domain wall movement. Dispersing them inside acts as a starting point for cracking during punching and improves punchability while minimizing the accumulation of processing strain on the base metal around the fracture surface to suppress the deterioration of the magnetic properties of the steel sheet. The object of the present invention is to provide a non-oriented electrical steel sheet capable of simplifying annealing after punching and improving magnetic properties.
本発明の要旨は次の通りである。
（１）質量％で、Ｃ：０．０１％以下、Ｓｉ：０．１％以上７．０％以下、Ａｌ：０．０１％以上３．０％以下、Ｍｎ：０．１％以上２．０％以下、Ｎ：０．００５％以下、Ｓ：０．００５％以下、Ｏ：０．００５％以上０．０２％以下を含有し、残部が鉄および不可避的不純物からなり、かつ直径２μｍ以上２５μｍ以下の、アルミナまたはシリカの１種以上からなる酸化物を１００個／ｍｍ３以上１０００００個／ｍｍ３以下含有することを特徴とする、打ち抜き加工性と鉄損に優れた無方向性電磁鋼板。
（２）質量％で、Ｃ：０．０１％以下、Ｓｉ：０．１％以上７．０％以下、Ａｌ：０．０１％以上３．０％以下、Ｍｎ：０．１％以上２．０％以下、Ｎ：０．００５％以下、Ｓ：０．０１％以下、Ｏ：０．００５％以上０．０２％以下、ＲＥＭ：０．０００５％以上０．０５％以下を含有し、残部が鉄および不可避的不純物からなり、かつ直径２μｍ以上２５μｍ以下の、ＲＥＭ酸硫化物、もしくはＲＥＭ酸化物およびＲＥＭ酸硫化物、またはこれに加えてアルミナもしくはシリカの１種以上からなる酸化物を１００個／ｍｍ３以上１０００００個／ｍｍ３以下含有することを特徴とする、打ち抜き加工性と鉄損に優れた無方向性電磁鋼板。
The gist of the present invention is as follows.
(1) By mass%, C: 0.01% or less, Si: 0.1% to 7.0%, Al: 0.01% to 3.0%, Mn: 0.1% to 2. 0% or less, N: 0.005% or less, S: 0.005% or less, O: 0.005% or more and 0.02% or less, with the balance being iron and inevitable impurities, and a diameter of 2 μm or more A non-oriented electrical steel sheet excellent in punching workability and iron loss, characterized by containing 100 / mm 3 or more and 100000 / mm 3 or less of an oxide composed of one or more of alumina or silica having a size of 25 μm or less .
(2) By mass%, C: 0.01% or less, Si: 0.1% to 7.0%, Al: 0.01% to 3.0%, Mn: 0.1% to 2. 0% or less, N: 0.005% or less, S: 0.01% or less, O: 0.005% or more and 0.02% or less, REM: 0.0005% or more and 0.05% or less, and the balance 100 consisting of REM oxysulfide, REM oxide and REM oxysulfide, or in addition to oxides of one or more of alumina or silica, having a diameter of 2 μm to 25 μm. pieces / mm 3 or more 100000 /, characterized in that mm 3 containing less, non-oriented electrical steel sheet excellent in punching processability and iron loss.
（３）質量％で、Ｃ：０．０１％以下、Ｓｉ：０．１％以上７．０％以下、Ａｌ：０．０１％以上３．０％以下、Ｍｎ：０．１％以上２．０％以下、Ｎ：０．００５％以下、Ｓ：０．００５％以下、Ｏ：０．００５％以上０．０２％以下を含有し、残部が鉄および不可避的不純物からなる溶鋼に、アルミナまたはシリカの１種以上からなる酸化物を添加し鋳造することを特徴とする、打ち抜き加工性と鉄損に優れた無方向性電磁鋼鋳片の製造方法。
（４）質量％で、Ｃ：０．０１％以下、Ｓｉ：０．１％以上７．０％以下、Ａｌ：０．０１％以上３．０％以下、Ｍｎ：０．１％以上２．０％以下、Ｎ：０．００５％以下、Ｓ：０．０１％以下、Ｏ：０．００５％以上０．０２％以下、ＲＥＭ：０．０００５％以上０．０５％以下を含有し、残部が鉄および不可避的不純物からなる溶鋼に、アルミナ、シリカ、ＲＥＭ酸化物あるいはＲＥＭ酸硫化物の１種以上からなる酸化物を添加し鋳造することを特徴とする、打ち抜き加工性と鉄損に優れた無方向性電磁鋼鋳片の製造方法。
（５）酸化物を鋳型内に添加し鋳造することを特徴とする、（３）または（４）に記載の打ち抜き加工性と鉄損に優れた無方向性電磁鋼鋳片の製造方法。
(3) By mass%, C: 0.01% or less, Si: 0.1% or more and 7.0% or less, Al: 0.01% or more and 3.0% or less, Mn: 0.1% or more. 0% or less, N: 0.005% or less, S: 0.005% or less, O: 0.005% or more and 0.02% or less, with the balance being iron or inevitable impurities, A method for producing a non-oriented electrical steel slab excellent in punching workability and iron loss, characterized by adding and casting an oxide composed of one or more types of silica.
(4) By mass%, C: 0.01% or less, Si: 0.1% to 7.0%, Al: 0.01% to 3.0%, Mn: 0.1% to 2. 0% or less, N: 0.005% or less, S: 0.01% or less, O: 0.005% or more and 0.02% or less, REM: 0.0005% or more and 0.05% or less, and the balance Is excellent in punching workability and iron loss, characterized by adding and casting one or more oxides of alumina, silica, REM oxide or REM oxysulfide to molten steel consisting of iron and inevitable impurities A method for producing non-oriented electrical steel slabs.
(5) The method for producing a non-oriented electrical steel slab excellent in punching workability and iron loss according to (3) or (4), wherein an oxide is added into a mold and casted.
なお、上記の（２）において、ＲＥＭ酸硫化物、もしくはＲＥＭ酸化物およびＲＥＭ酸硫化物、またはこれに加えてアルミナもしくはシリカの１種以上からなる酸化物とは、「ＲＥＭ酸硫化物」、「ＲＥＭ酸化物およびＲＥＭ酸硫化物」でも良く、さらに「ＲＥＭ酸硫化物に加えて、アルミナもしくはシリカの１種以上からなる酸化物」、「ＲＥＭ酸化物およびＲＥＭ酸硫化物に加えて、アルミナもしくはシリカの１種以上からなる酸化物」でも良いことを意味している。 In the above (2), the REM oxysulfide, or the REM oxide and the REM oxysulfide, or in addition to this, an oxide composed of one or more of alumina or silica is “REM oxysulfide”, “REM oxide and REM oxysulfide” may be used, and “in addition to REM oxysulfide, oxide composed of one or more of alumina or silica”, “REM oxide and REM oxysulfide, and alumina Alternatively, it may be an oxide composed of one or more kinds of silica.
また、上記の直径２μｍ以上２５μｍ以下の「アルミナ、シリカ、ＲＥＭ酸硫化物、ＲＥＭ酸化物」を、介在物と記載する場合がある。
また、上記の介在物の直径とは円球相当直径を意味する。以降下、介在物の球相当直径を単に直径と略記する。なお、円相当直径とは、介在物の断面積と同じ面積の円の直径を意味している。
In addition, “alumina, silica, REM oxysulfide, REM oxide” having a diameter of 2 μm to 25 μm may be referred to as inclusions.
In addition, the diameter of the inclusion means a sphere equivalent diameter. Hereinafter, the sphere equivalent diameter of inclusions is simply abbreviated as diameter. The equivalent circle diameter means the diameter of a circle having the same area as the cross-sectional area of the inclusion.
本発明により、打ち抜きの寸法精度が良く、工具寿命が延長でき、かつ打ち抜きによる磁気特性の劣化が少ない無方向性電磁鋼板を提供できる。 According to the present invention, it is possible to provide a non-oriented electrical steel sheet that has good punching dimensional accuracy, can extend the tool life, and has little deterioration in magnetic properties due to punching.
以下に、本発明の作用およびメカニズムについて詳細に説明する。
本発明者らは、介在物が打ち抜き性に及ぼす影響を明らかにするために、打ち抜き性の良い鋼板の打ち抜き破断面を詳細に調査検討した。その結果の一例として、打ち抜き性の良い鋼板の打ち抜き後の破断面を図１および図２に示す。
Hereinafter, the operation and mechanism of the present invention will be described in detail.
In order to clarify the influence of inclusions on the punchability, the present inventors have investigated and examined in detail the punched fracture surface of a steel plate having good punchability. As an example of the result, the fracture surface after punching of a steel plate with good punchability is shown in FIGS.
打ち抜き性の良い鋼板では、図１のＡおよび図２のＢに示す介在物が起点となって割れが発生し、打ち抜き方向に割れが伝播しており、このような形態の破断面が多数見出された。一方、比較のために打ち抜き性が劣る鋼板の破断面を調査したところ、破断面には介在物による影響が認められなかった。即ち、打ち抜き性の良い鋼板では介在物が起点となって割れ、打ち抜き方向に割れが伝播し、打ち抜き時の荷重が軽くなることが明らかであった。 In a steel sheet with good punchability, cracks are generated starting from the inclusions shown in A of FIG. 1 and B of FIG. 2, and the crack propagates in the punching direction. It was issued. On the other hand, when a fracture surface of a steel sheet having poor punchability was investigated for comparison, the fracture surface was not affected by inclusions. That is, it was clear that a steel sheet with good punchability cracks starting from inclusions, propagates in the punching direction, and lightens the load during punching.
また、上述の鋼板の表面から板厚中心まで研磨し、光学顕微鏡により介在物を調査したところ、種々直径の介在物が観察されたが、打ち抜き後の破断面で割れ起点となった介在物の直径は２μｍから２５μｍまでの範囲内にあり、この範囲外の大きさの介在物は割れ起点として作用しないことが判明した。 Moreover, when the inclusions were polished from the surface of the steel plate to the center of the plate thickness and investigated for inclusions with an optical microscope, inclusions with various diameters were observed, but the inclusions that became crack initiation points on the fracture surface after punching were observed. It was found that the diameter was in the range of 2 μm to 25 μm, and inclusions outside this range did not act as crack initiation points.
次いで、本発明者らは以下に示す実験を行い、鋼板中の介在物と鋼板の磁気特性ならびに打ち抜き性との関係について鋭意検討した。 Next, the present inventors conducted the following experiment and intensively studied the relationship between the inclusions in the steel sheet and the magnetic properties and punchability of the steel sheet.
成分を表１に示す通りに種々変更した鋼を溶解し、後述の実施例１に示す方法によって酸化物を添加し、連続鋳造し、熱間圧延し、厚さ０．５ｍｍに冷間圧延し、８５０℃×３０秒の仕上げ焼鈍を施し、絶縁皮膜を塗布して製品板を作成した。
次に、製品板の表面から板厚中心まで研磨し、光学顕微鏡により介在物の直径と個数を測定し、割れ起点として作用する直径が２μｍ以上２５μｍ以下の介在物について個数密度を算出した。介在物の組成はＳＥＭ−ＥＤＸにより分析した。また、製品板を高速打ち抜き機により、クリアランス０．１mmで２５cm長に打ち抜き、ＪＩＳ−Ｃ−２５５０エプスタイン法により磁気特性を調査した。
As shown in Table 1, steels with various changes were melted, oxides were added by the method shown in Example 1 described later, continuous casting, hot rolling, and cold rolling to a thickness of 0.5 mm. A final annealing was performed at 850 ° C. for 30 seconds, and an insulating film was applied to prepare a product plate.
Next, polishing was performed from the surface of the product plate to the center of the plate thickness, the diameter and number of inclusions were measured with an optical microscope, and the number density was calculated for inclusions having a diameter of 2 μm or more and 25 μm or less that acted as a crack starting point. The inclusion composition was analyzed by SEM-EDX. Further, the product plate was punched to a length of 25 cm with a clearance of 0.1 mm using a high-speed punching machine, and the magnetic characteristics were investigated by the JIS-C-2550 Epstein method.
打ち抜き性に関しては、以下の方法で調査し評価した。まず、高速打ち抜き機により、クリアランス０．１mmで径１２mmの円形に打ち抜き加工した。その際、ポンチにセットしたロードセルにより打ち抜き荷重を測定した。さらに、連続打ち抜きを行い、打ち抜き後の鋼板のダレ高さを測定し、ダレ高さが板厚の１割（５０μｍ）となるまでの打ち抜き回数、及び１０５回連続打ち抜き後の工具の磨耗状態を調査した。以上の結果を表１、表２および図３に示す。 The punchability was investigated and evaluated by the following method. First, it was punched into a circle with a clearance of 0.1 mm and a diameter of 12 mm with a high-speed punching machine. At that time, the punching load was measured with a load cell set in a punch. Further, the continuous punching, the sag height of the steel sheet after punching is measured, the wear state of the sagging punching number up to a height of 1% of the thickness (50 [mu] m), and 10 5 times after successive punching tool investigated. The above results are shown in Table 1, Table 2 and FIG.
表２のＮo.１−１からＮo.１−６に示すように、製品板中の直径が２μｍ以上２５μｍ以下の介在物の組成、ならびに個数密度が本発明範囲内にある場合、打ち抜き加工後の製品板の鉄損（W１５／５０）値は４．９〜５．１ｗ／ｋｇと低く、磁気特性が良好であった。また、打ち抜き時の破断荷重が６．４５〜６．５ｋＮと低く、連続可能な打ち抜き回数が１．８×１０５〜２．２×１０５回と多く、所定回数の連続打ち抜き後の工具磨耗も問題なく、打ち抜き性が良好であった。このとき、打ち抜き後の破断面には、図１および図２に示すような介在物が起点となった割れが多数観察された。 As shown in No. 1-1 to No. 1-6 in Table 2, when the composition of inclusions having a diameter in the product plate of 2 μm or more and 25 μm or less and the number density are within the range of the present invention, The iron loss (W15 / 50) value of the product plate was as low as 4.9 to 5.1 w / kg, and the magnetic properties were good. Moreover, the breaking load at the time of punching is as low as 6.45 to 6.5 kN, the number of continuous punching is as high as 1.8 × 10 5 to 2.2 × 10 5 times, and tool wear after a predetermined number of continuous punching There was no problem, and the punchability was good. At this time, many cracks starting from inclusions as shown in FIGS. 1 and 2 were observed on the fractured surface after punching.
一方、表２のＮo.１−７、１−８、１−１１に示すように、製品板中の直径が２μｍ以上２５μｍ以下の介在物の個数密度が本発明範囲を下回る場合には、打ち抜き加工後の製品板の鉄損値は４．９〜５．０ｗ／ｋｇと低く、磁気特性が良好であった。しかし、打ち抜き時の破断荷重が６．７５〜６．８０ｋＮと高く、また打ち抜き回数が０．７×１０５〜０．８×１０５回で打ち抜き後の工具に端面のダレが発生し、工具の調整が必要となり、打ち抜き性が劣位であった。 On the other hand, as shown in Nos. 1-7, 1-8, and 1-11 in Table 2, when the number density of inclusions having a diameter of 2 μm or more and 25 μm or less in the product plate is below the range of the present invention, punching is performed. The iron loss value of the processed product plate was as low as 4.9 to 5.0 w / kg, and the magnetic properties were good. However, the breaking load at the time of punching is as high as 6.75 to 6.80 kN, and when the number of times of punching is 0.7 × 10 5 to 0.8 × 10 5 times, sagging of the end face occurs in the tool after punching. Therefore, the punchability was inferior.
また、表２のＮo.１−９とＮo.１−１０に示すように、製品板中の直径が２μｍ以上２５μｍ以下の介在物の個数密度が本発明範囲を上回る場合には、打ち抜き時の破断荷重が６．４ｋＮと低く、連続可能な打ち抜き回数が２×１０５〜２．５×１０５回と多く、所定回数の連続打ち抜き後の工具磨耗も問題なく、打ち抜き性が良好であったものの、打ち抜き加工後の製品板の鉄損値は５．９〜６．３ｗ／ｋｇと高く、磁気特性が不良であった。 As shown in No. 1-9 and No. 1-10 in Table 2, when the number density of inclusions having a diameter of 2 μm or more and 25 μm or less in the product plate exceeds the range of the present invention, The breaking load was as low as 6.4 kN, the number of continuous punching operations was as high as 2 × 10 5 to 2.5 × 10 5 times, and there was no problem with tool wear after a predetermined number of continuous punching, and the punching performance was good. However, the iron loss value of the product plate after punching was as high as 5.9 to 6.3 w / kg, and the magnetic properties were poor.
以上示した通り、鋼板中における直径が２μｍ以上２５μｍ以下の介在物の個数密度と、打ち抜き時の最大荷重の関係は、図３に示す通りであり、介在物の個数密度が１００個／ｍｍ３を上回ると、最大荷重が低下し、より小さい加重で打ち抜けるようになり、打ち抜き性が向上することが判った。また、介在物の個数密度が１０００個／ｍｍ３を上回ると、最大荷重がさらに低下し、さらに小さい加重で打ち抜けるようになり、打ち抜き性がさらに向上することが判った。 As shown above, the relationship between the number density of inclusions having a diameter of 2 μm or more and 25 μm or less in the steel sheet and the maximum load at the time of punching is as shown in FIG. 3, and the number density of inclusions is 100 / mm 3. It has been found that the maximum load decreases and the punching can be performed with a smaller load, and the punchability is improved. Further, it was found that when the number density of inclusions exceeds 1000 / mm 3 , the maximum load is further reduced and the punch can be punched with a smaller load, and the punchability is further improved.
一方、介在物の個数密度と磁気特性との関係については、図３に示す通り、鋼板中における直径が２μｍ以上２５μｍ以下の介在物の個数密度が１０００００個／ｍｍ３を上回ると、磁気特性が劣化することが明らかであった。これは、介在物によって結晶粒成長がピン止め阻害される作用と、介在物によって磁壁移動がピン止め阻害される作用による影響と思われる。 On the other hand, regarding the relationship between the number density of inclusions and magnetic properties, as shown in FIG. 3, when the number density of inclusions having a diameter of 2 μm or more and 25 μm or less in a steel sheet exceeds 100,000 / mm 3 , the magnetic properties are increased. It was clear that it deteriorated. This is considered to be due to the effect of pinching inhibition of crystal grain growth by inclusions and the effect of pinning inhibition of domain wall movement by inclusions.
以上により、打ち抜き性を良好としつつ磁気特性を良好に保つための、介在物の個数密度に適正な範囲があることが判明した。 From the above, it has been found that there is an appropriate range for the number density of inclusions in order to maintain good magnetic properties while improving punchability.
さらに、本発明の介在物の具備すべき条件について、より詳細に説明する。
上述の鋼板にはＭｎＳなどの比較的低い融点の介在物が少数ながら観察されたが、それらは破断の起点に存在せず、割れ起点となった介在物の組成はアルミナやシリカであった。これらの酸化物は融点が比較的高く、熱間圧延や焼鈍中に軟質化して変形することはなく、圧延によって延伸することがない。
Furthermore, the conditions that the inclusion of the present invention should have will be described in more detail.
Although a small number of inclusions having a relatively low melting point such as MnS were observed in the steel sheet described above, they were not present at the starting point of fracture, and the composition of the inclusions that became the starting point of cracking was alumina or silica. These oxides have a relatively high melting point, do not soften and deform during hot rolling or annealing, and do not stretch by rolling.
この理由は、低融点の介在物は比較的軟質であるため、鋼板に打ち抜き応力が加わったときに介在物の表面で滑りが発生してしまい、有効な割れ起点にならないが、高融点の介在物は熱間圧延中や焼鈍中に軟質化し延伸することがなく、また鋼板の打ち抜き加工時には、介在物が比較的硬質で変形しないため、割れ起点として有効に作用すると考えられる。以下、アルミナやシリカの介在物を硬質酸化物と称する。 The reason for this is that inclusions with a low melting point are relatively soft, so that when punching stress is applied to the steel sheet, slippage occurs on the surface of the inclusions, which does not become an effective crack starting point, but inclusions with a high melting point It is considered that the material softens and does not stretch during hot rolling or annealing, and the inclusions are relatively hard and do not deform during punching of the steel sheet, so that it is considered that the material effectively acts as a crack starting point. Hereinafter, the inclusion of alumina or silica is referred to as a hard oxide.
また、鋼中のＭｎやＳの含有量が比較的多いとき、硬質介在物の周囲にＭｎＳなどの硫化物が析出し、硬質介在物が覆われる場合がある。硬質介在物が硫化物で覆われると、硬質介在物の表面で滑りが発生してしまい、有効な割れ起点にならず好ましくない。よって、硫化物で覆われた介在物は硬質介在物に含まない。また、鋼中のＭｎやＳの含有量が比較的多いときに、硬質介在物を打ち抜き加工時の破断起点として有効に機能させるためには、ＭｎＳなどの硫化物を抑制することが好ましい。 Further, when the content of Mn and S in the steel is relatively large, sulfides such as MnS may be deposited around the hard inclusions and the hard inclusions may be covered. If the hard inclusions are covered with sulfide, slippage occurs on the surface of the hard inclusions, which is not preferable because it is not an effective crack starting point. Therefore, inclusions covered with sulfide are not included in the hard inclusions. In addition, when the content of Mn and S in the steel is relatively high, it is preferable to suppress sulfides such as MnS in order to make the hard inclusions function effectively as a fracture starting point during punching.
電磁鋼中の硫化物を抑制する方法として、ＣａやＲＥＭなどの硫化物形成元素の添加によりＣａやＲＥＭなどの硫化物系介在物を鋼中に生成させて、鋼中のＳを固定し、鋼中のフリーＳを減少させる技術は従来から知られている。ここで、打ち抜き性を改善する観点では、後述の理由により、ＲＥＭの添加が好ましい。なお、ＲＥＭとは、原子番号が５７のランタンから７１のルテシウムまでの１５元素に原子番号が２１のスカンジウムと原子番号が３９のイットリウムを加えた合計１７元素の総称である。 As a method of suppressing sulfides in electromagnetic steel, sulfide inclusions such as Ca and REM are generated in steel by adding sulfide-forming elements such as Ca and REM, and S in steel is fixed. Techniques for reducing free S in steel have been conventionally known. Here, from the viewpoint of improving punchability, addition of REM is preferable for the reason described later. Note that REM is a generic name for a total of 17 elements including 15 elements from lanthanum having an atomic number of 57 to lutesium having an atomic number of 57 plus scandium having an atomic number of 21 and yttrium having an atomic number of 39.
打ち抜き時に、上記で述べた適正な硬質介在物が起点となって破断した場合、破断は硬質介在物の周囲から発生し鋼板に伝播するため、硬質介在物のない場合に比べて鋼板への歪の蓄積が少なくなり、打ち抜き後の鉄損が良好となる。また、鋼板がシャープに破断するため、打ち抜き後のダレが少なくなり、積み精度が向上するとともに工具調整の頻度が少なくなり生産性が向上する。 When a punch breaks with the appropriate hard inclusion mentioned above at the time of punching, the breakage occurs from the periphery of the hard inclusion and propagates to the steel plate. Accumulation of iron is reduced, and iron loss after punching is improved. In addition, since the steel sheet breaks sharply, sagging after punching is reduced, stacking accuracy is improved, and the frequency of tool adjustment is reduced, thereby improving productivity.
一方、従来知見に基づいて、潤滑性を持つ比較的軟質な介在物によって打ち抜き性を変化させた場合、鋼板内部での滑りによる歪の蓄積や、打ち抜き後のダレが避けられず、上記の効果を有効に奏することができない。 On the other hand, when the punchability is changed by a relatively soft inclusion having lubricity based on the conventional knowledge, accumulation of strain due to slip inside the steel plate and sag after punching cannot be avoided, and the above effect Cannot be played effectively.
さらにまた、電磁鋼中の硫化物を抑制するために、硫化物形成元素としてＣａを添加した場合、鋼中に形成されるＣａＳ自身が圧延により延伸し、延伸したＣａＳによって磁気特性や打ち抜き性の劣化が生じるので好ましくない。一方、硫化物形成元素としてＲＥＭを添加した場合、鋼中にＲＥＭ酸化物やＲＥＭ酸硫化物が形成されるが、いずれも圧延によって延伸することがない。そのため、ＭｎＳなどの軟質な介在物の生成を抑制する上、打ち抜き時の破断起点となって硬質介在物として効果を発揮するので好適である。 Furthermore, when Ca is added as a sulfide-forming element in order to suppress sulfides in the electrical steel, the CaS itself formed in the steel is stretched by rolling, and the stretched CaS exhibits magnetic properties and punchability. Since deterioration occurs, it is not preferable. On the other hand, when REM is added as a sulfide-forming element, REM oxide and REM oxysulfide are formed in the steel, but none of them are stretched by rolling. Therefore, it is preferable because it suppresses the generation of soft inclusions such as MnS and also serves as a hard starting inclusion as a breakage starting point during punching.
以上示した通り、製品板中の介在物が硬質介在物であり、かつその直径ならびに個数密度が本発明範囲内にある場合には、打ち抜き加工後の製品板の磁気特性が良好であり、打ち抜き性に優れ、工具寿命の延長が図れることが確認された。 As shown above, when the inclusions in the product plate are hard inclusions and the diameter and number density are within the scope of the present invention, the magnetic properties of the product plate after punching are good, It was confirmed that the tool life was excellent and the tool life could be extended.
次に、本発明における成分組成の好ましい含有量の限定理由について説明する。
［Ｃ］：Ｃは、磁気特性に有害となるばかりか、Ｃの析出による磁気時効が著しくなるので、上限を０．０１質量％とした。下限は０質量％を含む。
［Ｓｉ］：Ｓｉは鉄損を減少させる元素である。下限の０．１質量％より少ないと鉄損が悪化する。また、上限の７．０質量％を超えると打ち抜き性が著しく不良となるため、上限を７．０質量％とした。
Next, the reason for limiting the preferable content of the component composition in the present invention will be described.
[C]: C is not only harmful to magnetic properties, but also magnetic aging due to precipitation of C becomes remarkable, so the upper limit was made 0.01 mass%. The lower limit includes 0% by mass.
[Si]: Si is an element that reduces iron loss. When less than the lower limit of 0.1% by mass, the iron loss is worsened. Further, when the upper limit of 7.0% by mass is exceeded, the punchability becomes extremely poor, so the upper limit was set to 7.0% by mass.
［Ａｌ］：ＡｌはＳｉ同様に鉄損を減少させる元素である。下限の０．０１質量％未満では鉄損が悪化し、上限の３．０質量％を超えるとコストの増加が著しい。 また、製品板中にアルミナを生成させる観点から、Ａｌの下限として好ましくは０．０１５質量％、より好ましくは０．０２質量％とする。
［Ｍｎ］：Ｍｎは鋼板の硬度を増加させ、打ち抜き性を改善するために、０．１質量％以上添加する。なお、上限の２．０質量％は経済的理由によるものである。
[Al]: Al is an element that reduces iron loss in the same manner as Si. If the lower limit is less than 0.01% by mass, the iron loss deteriorates, and if it exceeds the upper limit of 3.0% by mass, the cost increases remarkably. Further, from the viewpoint of generating alumina in the product plate, the lower limit of Al is preferably 0.015% by mass, more preferably 0.02% by mass.
[Mn]: Mn is added in an amount of 0.1% by mass or more in order to increase the hardness of the steel sheet and improve the punchability. The upper limit of 2.0% by mass is due to economic reasons.
［Ｎ］：ＮはＡｌＮやＴｉＮなどの窒化物となり鉄損を悪化させるため、上限として０．００５質量％とした。下限は０質量％を含む。
［Ｓ］：ＳはＭｎＳ等の硫化物となり、粒成長性を悪化させ、鉄損を悪化させる。また、硬質介在物を覆って析出する場合もあるが、この場合は打ち抜きの破断起点としての硬質介在物の効果を損ねるため、上限を０．００５質量％とした。
但し、後述の通り、ＲＥＭを添加すると酸硫化物を形成してＳが固定されるので、ＲＥＭを添加した場合にはＳの上限は０．０１質量％でよい。なお下限は０質量％を含む。
[N]: N is a nitride such as AlN or TiN and deteriorates the iron loss. Therefore, the upper limit is set to 0.005% by mass. The lower limit includes 0% by mass.
[S]: S becomes a sulfide such as MnS, which deteriorates grain growth and iron loss. Moreover, although it may deposit covering a hard inclusion, in this case, in order to impair the effect of the hard inclusion as a rupture starting point of punching, the upper limit was made 0.005% by mass.
However, as described later, when REM is added, an oxysulfide is formed and S is fixed. Therefore, when REM is added, the upper limit of S may be 0.01% by mass. The lower limit includes 0% by mass.
［Ｏ］：Ｏは打ち抜きの破断起点としての硬質介在物を生成させ、有効に機能させる。鋼中のＯには酸化物を形成するものと溶存するものがあるが、本願発明範囲においては微量の溶存Ｏが存在するものの、実質的には酸化物を構成しており、０．００５質量％以上は必要である。ただし、Ｏは過剰に含有されると酸化物が多数生成し、この酸化物によって磁壁移動や結晶粒成長が阻害されるので、０．０２質量％以下とする。 [O]: O generates a hard inclusion as a starting point of punching breakage and functions effectively. O in the steel includes an oxide that forms an oxide and a dissolved one, but in the scope of the present invention, although a small amount of dissolved O exists, the oxide substantially constitutes an oxide, and 0.005 mass % Or more is necessary. However, if O is contained excessively, a large number of oxides are formed, and domain wall movement and crystal grain growth are inhibited by these oxides, so the content is made 0.02% by mass or less.
以上に述べた成分組成の鋼において、本発明の作用効果を発揮させるための別の形態として、ＲＥＭを添加しても良い。
［ＲＥＭ］：ＲＥＭは酸硫化物を形成してＳを固定し、ＭｎＳなどの比較的軟質な介在物が多数生成することを抑制する。０．０００５質量％以上であれば充分であるが、経済的な理由により上限を０．０５質量％とする。
In the steel having the component composition described above, REM may be added as another form for exhibiting the effects of the present invention.
[REM]: REM forms oxysulfide to fix S, and suppresses the generation of a large number of relatively soft inclusions such as MnS. Although 0.0005 mass% or more is sufficient, the upper limit is set to 0.05 mass% for economic reasons.
以上、述べてきた元素の他にも、本願の鋼の効果を大きくさまたげるものでなければ、公知の元素を添加することが可能である。以下に、選択元素について説明する。尚、これらの含有量の下限値は、微量でも含有されていれば良いため、すべて０質量％超とする。 In addition to the elements described above, known elements can be added as long as the effects of the steel of the present application are not greatly affected. Below, a selective element is demonstrated. In addition, since the lower limit of these content should just be contained even if it is trace amount, it is all over 0 mass%.
［Ｐ］：Ｐは材料の強度を高め、打ち抜き性を改善する。但し、過剰な場合は冷延性を損ねるため、０．１質量％以下が好ましい。
［Ｃｕ］：Ｃｕは耐食性を向上させ、また固有抵抗を高めて鉄損を改善する。但し、過剰な場合は製品板の表面にヘゲ疵などが発生して表面品位を損ねるため、０．５質量％以下が好ましい。
［Ｃａ］：Ｃａは脱硫元素であり、鋼中のＳと反応してサルファイドを形成し、Ｓを固定する。しかしＲＥＭと異なり、過剰にＣａ添加すると、鋼中に生成したＣａＳが圧延により延伸し、磁気特性や打ち抜き性の劣化の原因となる。よって０．０５質量％以下が好ましい。
[P]: P increases the strength of the material and improves punchability. However, if excessive, the cold rolling property is impaired, so 0.1% by mass or less is preferable.
[Cu]: Cu improves corrosion resistance and increases specific resistance to improve iron loss. However, if the amount is excessive, scabs or the like are generated on the surface of the product plate and the surface quality is impaired, so 0.5 mass% or less is preferable.
[Ca]: Ca is a desulfurization element, reacts with S in steel to form sulfide, and fixes S. However, unlike REM, when Ca is added excessively, CaS produced in the steel is stretched by rolling, which causes deterioration of magnetic properties and punchability. Therefore, 0.05 mass% or less is preferable.
次に、本発明における好ましい製造条件、ならびにその規定理由について説明する。
まず製鋼段階において、転炉や２次精錬炉などの常法により精錬し、所望の組成範囲内の溶鋼を溶製した後、取鍋からノズルを介して鋳型内に溶鋼を注入し、連続鋳造、ないしインゴット鋳造を行ってスラブ等の鋳片を鋳造する。
鋳造に際し、酸素源としての酸化物（以下、これを酸素源と称する）を溶鋼に供給して所定の介在物を作りこむ。
尚、酸化源としては、アルミナやシリカが、入手が容易であることから、最も推奨される。また、鋼中にＲＥＭを含有させる場合は、含有ＲＥＭ酸化物やＲＥＭ酸硫化物を用いても良い。
Next, preferable manufacturing conditions in the present invention and the reasons for their definition will be described.
First, in the steelmaking stage, the steel is refined by conventional methods such as converters and secondary refining furnaces, molten steel in the desired composition range is melted, and then the molten steel is injected into the mold from the ladle through the nozzle and continuously cast. Or, ingot casting is performed to cast a slab or other slab.
In casting, an oxide as an oxygen source (hereinafter referred to as an oxygen source) is supplied to the molten steel to form predetermined inclusions.
As an oxidation source, alumina and silica are most recommended because they are easily available. Moreover, when REM is contained in steel, a contained REM oxide or REM oxysulfide may be used.
これらの酸素源を溶鋼に添加すると、酸素源は溶鋼中で一旦分解して酸素を溶鋼に放出し、その酸素が溶鋼と反応して酸化物を形成した結果、硬質酸化物が多数生成すると推察される。このとき、取鍋以前の溶鋼に酸素源を供給すると、溶鋼中で酸素源が浮上分離して歩留まりが悪化する上、前述のノズルが酸素源によって閉塞して鋳型への溶鋼供給が阻害される場合もあり好ましくない。そこで、ノズルから鋳型内に溶鋼が吐出された後に酸素源を供給し、溶鋼と酸素源を混合させて鋳造を行えばよい。 When these oxygen sources are added to the molten steel, the oxygen source is once decomposed in the molten steel to release oxygen to the molten steel, and the oxygen reacts with the molten steel to form oxides. Is done. At this time, if an oxygen source is supplied to the molten steel before the ladle, the oxygen source floats and separates in the molten steel and the yield deteriorates, and the nozzle is blocked by the oxygen source and the molten steel supply to the mold is hindered. In some cases, it is not preferable. Therefore, casting may be performed by supplying the oxygen source after the molten steel is discharged from the nozzle into the mold and mixing the molten steel and the oxygen source.
溶鋼に酸素源を供給する方法は種々あるが、その一例として、酸素源にアルミナを用いた場合で説明すると、所定のアルミナを薄肉鉄管に詰めたワイヤーを用い、ワイヤーをノズル吐出流に供給して酸素源を溶鋼と混合すればよい。この方法により、製品板中の硬質酸化物の組成、サイズならびに個数密度を本発明範囲内に調整するためには、アルミナ（Ａｌ２Ｏ３）と酸化鉄（Ｆｅ２Ｏ３）を質量比で３：１〜１：３の範囲内に配合して混合した粉末を薄肉鉄管に詰めたワイヤーを用いるとよい。この粉末としては直径が１mm以下の粉粒を焼結せず用いると、溶鋼中での分散性が良く好適である。 There are various methods for supplying an oxygen source to molten steel. For example, when alumina is used as the oxygen source, a wire in which a predetermined alumina is packed in a thin iron pipe is used, and the wire is supplied to the nozzle discharge flow. The oxygen source may be mixed with the molten steel. By this method, in order to adjust the composition, size and number density of the hard oxide in the product plate within the range of the present invention, alumina (Al 2 O 3 ) and iron oxide (Fe 2 O 3 ) in mass ratio. It is good to use the wire which packed the powder mix | blended and mixed in the range of 3: 1 to 1: 3 to the thin-walled iron pipe. As this powder, it is preferable to use powder particles having a diameter of 1 mm or less without sintering because of good dispersibility in molten steel.
なお、アルミナと酸化鉄を混合する理由は、酸素源と溶鋼の濡れ性を改善し、溶鋼中での酸素源クラスターの生成を抑制し、クラスターの浮上による酸素源ロスを低減して酸素歩留まりと分散性を改善するためである。ここで、酸素歩留まりとは、供給した酸素源中の含有酸素量に対する、酸素源供給によって増加した鋼中の酸素量の割合を意味する。ワイヤー供給による酸素歩留まりが２０〜４０％であることを考慮し、供給した酸素源によって溶鋼中に酸素が供給され、鋼中の硬質酸化物の組成、サイズならびに個数密度が本発明範囲内になるように、溶鋼の吐出流量に応じたワイヤー供給速度で供給する。これにより、本発明範囲を具備した硬質介在物を鋼中に生成させることが可能となる。 The reason for mixing alumina and iron oxide is to improve the wettability of the oxygen source and the molten steel, suppress the generation of oxygen source clusters in the molten steel, reduce the oxygen source loss due to cluster levitation, and increase the oxygen yield. This is for improving dispersibility. Here, the oxygen yield means the ratio of the amount of oxygen in the steel increased by supplying the oxygen source to the amount of oxygen contained in the supplied oxygen source. Considering that the oxygen yield by wire supply is 20 to 40%, oxygen is supplied into the molten steel by the supplied oxygen source, and the composition, size and number density of the hard oxide in the steel are within the range of the present invention. Thus, it supplies with the wire supply speed according to the discharge flow rate of molten steel. Thereby, it becomes possible to produce | generate the hard inclusion which comprised the scope of the present invention in steel.
この後、鋳片を熱間圧延し、必要に応じて熱延板焼鈍し、一回または中間焼鈍を挟む二回以上の冷間圧延により製品厚に仕上げ、次いで仕上げ焼鈍し、絶縁皮膜を塗布する。以上述べた方法により、製品板中の介在物を本発明範囲内に制御することが可能となる。 After this, the slab is hot-rolled, hot-rolled sheet annealed as necessary, finished to product thickness by one or more cold rollings sandwiching intermediate or intermediate annealing, then finish-annealed and coated with insulating film To do. By the method described above, the inclusions in the product plate can be controlled within the scope of the present invention.
成分を表１に示す通りに種々変更した鋼を溶解し、アルミナ（Ａｌ２Ｏ３）と酸化鉄（Ｆｅ２Ｏ３）を質量比で１：１で混合した平均粒径０．８mmの酸化物粉末をワイヤーに被覆して３〜４ｋｇ／ｍｉｎの供給速度で鋳型内に供給し、鋳型への溶鋼の吐出流量を３トン／ｍｉｎとして連続鋳造し、熱間圧延し、厚さ０．５ｍｍに冷間圧延し、８５０℃×３０秒の仕上げ焼鈍を施し、通常の無方向性電磁鋼板に塗布される有機成分と無機成分を含有する絶縁皮膜を塗布して製品板を作成した。 As shown in Table 1, steels with various changes were dissolved, and alumina (Al 2 O 3 ) and iron oxide (Fe 2 O 3 ) were mixed at a mass ratio of 1: 1. The product powder is coated on a wire and supplied into the mold at a supply rate of 3 to 4 kg / min, continuously cast with a molten steel discharge flow rate of 3 tons / min, hot-rolled, and a thickness of 0.5 mm. The plate was cold-rolled and subjected to finish annealing at 850 ° C. for 30 seconds, and an insulating film containing an organic component and an inorganic component applied to a normal non-oriented electrical steel sheet was applied to prepare a product plate.
次に、製品板の直径が２μｍ以上２５μｍ以下の介在物について個数密度を光学顕微鏡により調査し、また、介在物組成をＳＥＭ−ＥＤＸにより分析した。また、製品板を高速打ち抜き機によりクリアランス０．１mmで２５cm長に打ち抜き、ＪＩＳ−Ｃ−２５５０に示すエプスタイン法で磁気特性を調査した。また、高速打ち抜き機によりクリアランス０．１mmで径１２mmの円形に打ち抜き加工し、打ち抜き荷重を測定した。さらに、連続打ち抜きを行い、打ち抜き後の鋼板のダレ高さを測定し、ダレ高さが板厚の１割（５０μｍ）となるまでの打ち抜き回数、及び１０５回連続打ち抜き後の工具の磨耗状態を調査した。 また、打ち抜き破断面をＳＥＭ−ＥＤＸにより調査し、介在物組成を分析した。なお、打ち抜きに際して水溶性の潤滑油を用いた。 Next, the number density of the inclusions having a product plate diameter of 2 μm or more and 25 μm or less was examined by an optical microscope, and the inclusion composition was analyzed by SEM-EDX. Further, the product plate was punched to a length of 25 cm with a clearance of 0.1 mm using a high-speed punching machine, and the magnetic characteristics were investigated by the Epstein method shown in JIS-C-2550. Further, a punching process was performed with a high-speed punching machine into a circle having a clearance of 0.1 mm and a diameter of 12 mm, and the punching load was measured. Further, the continuous punching, the sag height of the steel sheet after punching is measured, the wear state of the sagging punching number up to a height of 1% of the thickness (50 [mu] m), and 10 5 times after successive punching tool investigated. Moreover, the punching fracture surface was investigated by SEM-EDX, and the inclusion composition was analyzed. A water-soluble lubricating oil was used for punching.
以上の結果を表２及び図１〜３に示す。打ち抜き破断面の割れ起点には直径２μｍ以上２５μｍ以下の硬質介在物が観察され、それ以外の介在物は観察されなかった。また、表２及び図３に示した通り、化学成分及び介在物が本発明の範囲内の製品板は、鉄損値ならびに打ち抜き性に関して良好な結果が得られた。一方、化学成分及び介在物が本発明範囲外の製品板は、鉄損値や打ち抜き性が劣る結果が得られた。 The above results are shown in Table 2 and FIGS. Hard inclusions having a diameter of 2 μm or more and 25 μm or less were observed at the crack starting point of the punched fracture surface, and other inclusions were not observed. Moreover, as shown in Table 2 and FIG. 3, the product plate in which the chemical components and inclusions are within the scope of the present invention gave good results with respect to the iron loss value and punchability. On the other hand, a product plate having chemical components and inclusions outside the scope of the present invention was inferior in iron loss value and punchability.
成分を表３に示す通りに調整した鋼を溶解し、アルミナ（Ａｌ２Ｏ３）と酸化鉄（Ｆｅ２Ｏ３）を質量比で１：１で混合した平均粒径０．８mmの酸化物粉末をワイヤーに被覆して３〜４ｋｇ／ｍｉｎの供給速度で鋳型内に供給し、溶鋼の吐出流量を３トン／ｍｉｎとして連続鋳造し、熱間圧延し、厚さ０．５ｍｍに冷間圧延し、８５０℃×３０秒の仕上げ焼鈍を施し、通常の無方向性電磁鋼板に塗布される有機成分と無機成分を含有する絶縁皮膜を塗布して製品板を作成した。 An oxide having an average particle size of 0.8 mm, in which steels whose components were adjusted as shown in Table 3 were dissolved and alumina (Al 2 O 3 ) and iron oxide (Fe 2 O 3 ) were mixed at a mass ratio of 1: 1. The powder is coated on the wire and supplied into the mold at a supply rate of 3 to 4 kg / min, continuously cast at a molten steel discharge flow rate of 3 tons / min, hot-rolled, and cold-rolled to a thickness of 0.5 mm. Then, finish annealing was performed at 850 ° C. for 30 seconds, and an insulating film containing an organic component and an inorganic component applied to a normal non-oriented electrical steel sheet was applied to prepare a product plate.
次に、製品板の直径が２μｍ以上２５μｍ以下の介在物について個数密度を光学顕微鏡により調査し、また、介在物組成をＳＥＭ−ＥＤＸにより分析した。また、製品板を高速打ち抜き機によりクリアランス０．１mmで２５cm長に打ち抜き、ＪＩＳ−Ｃ−２５５０に示すエプスタイン法で磁気特性を調査した。また、高速打ち抜き機によりクリアランス０．１mmで径１２mmの円形に打ち抜き加工し、打ち抜き荷重を測定した。さらに、連続打ち抜きを行い、打ち抜き後の鋼板のダレ高さを測定し、ダレ高さが板厚の１割（５０μｍ）となるまでの打ち抜き回数、及び１０５回連続打ち抜き後の工具の磨耗状態を調査した。また、打ち抜き破断面をＳＥＭ−ＥＤＸにより調査し、介在物組成を分析した。なお、打ち抜きに際して水溶性の潤滑油を用いた。 Next, the number density of the inclusions having a product plate diameter of 2 μm or more and 25 μm or less was examined by an optical microscope, and the inclusion composition was analyzed by SEM-EDX. Further, the product plate was punched to a length of 25 cm with a clearance of 0.1 mm using a high-speed punching machine, and the magnetic characteristics were investigated by the Epstein method shown in JIS-C-2550. Further, a punching process was performed with a high-speed punching machine into a circle having a clearance of 0.1 mm and a diameter of 12 mm, and the punching load was measured. Further, the continuous punching, the sag height of the steel sheet after punching is measured, the wear state of the sagging punching number up to a height of 1% of the thickness (50 [mu] m), and 10 5 times after successive punching tool investigated. Moreover, the punching fracture surface was investigated by SEM-EDX, and the inclusion composition was analyzed. A water-soluble lubricating oil was used for punching.
以上の結果を表４に示す。打ち抜き破断面の割れ起点には直径２μｍ以上２５μｍ以下の硬質介在物が観察され、それ以外の介在物は観察されなかった。また、表４のＮo.２−１からＮo.２−３に示すように、製品板中の介在物の組成ならびに個数密度が本発明範囲内にある場合、打ち抜き加工後の製品板の鉄損値は比較的低く、磁気特性が良好であり、かつ打ち抜き時の破断荷重は比較的低く、所定回数の連続打ち抜き後の工具磨耗も問題なく、打ち抜き性が良好であった。 The results are shown in Table 4. Hard inclusions having a diameter of 2 μm or more and 25 μm or less were observed at the crack starting point of the punched fracture surface, and other inclusions were not observed. Further, as shown in No. 2-1 to No. 2-3 of Table 4, when the composition and number density of inclusions in the product plate are within the scope of the present invention, the iron loss of the product plate after punching is performed. The value was relatively low, the magnetic properties were good, the breaking load at the time of punching was relatively low, the tool wear after a predetermined number of continuous punching was no problem, and the punchability was good.
一方、Ｎo.２−１に対してＮo.２−４は、鋼の成分が同等グレードであるが、製品板中の介在物の個数密度が本発明範囲を上回っており、鉄損値が比較的高く、磁気特性が不良であった。また、Ｎo.２−２に対してＮo.２−５は、鋼の成分が同等グレードであるが、製品板中の介在物の個数密度が本発明範囲を下回っており、打ち抜き回数が０．７×１０５回で打ち抜き後の工具に端面のダレが発生し、工具の調整が必要となり、打ち抜き性が劣位であった。また、Ｎo.２−３に対してＮo.２−６及びＮo.２−７は、鋼の成分が同等グレードであるが、Ｎo.２−６は製品板中の介在物の個数密度が本発明範囲を下回っており、打ち抜き回数が０．６×１０５回で打ち抜き後の工具に端面のダレが発生し、工具の調整が必要となり、打ち抜き性が劣位であり、またＮo.２−７は製品板中の介在物の個数密度が本発明範囲を上回っており、鉄損値が比較的高く、磁気特性が不良であった。
以上に示した通り、化学成分及び介在物が本発明範囲内の製品板は、化学成分及び介在物が本発明範囲外の製品板に比べ、鉄損値や打ち抜き性が良好な結果が得られた。
On the other hand, No. 2-4 has the same grade of steel as No. 2-1, but the number density of inclusions in the product plate exceeds the range of the present invention, and the iron loss value is compared. The magnetic properties were poor. In addition, No. 2-5 is equivalent to No. 2-2 in steel components, but the number density of inclusions in the product plate is below the range of the present invention, and the number of punches is 0. The sagging of the end face occurred in the tool after punching at 7 × 10 5 times, the tool had to be adjusted, and the punchability was inferior. In addition, No.2-6 and No.2-7 have the same grade of steel as No.2-3, but No.2-6 has the number density of inclusions in the product plate. It is below the scope of the invention, and the punching number is 0.6 × 10 5 times, and the end face of the tool after punching occurs, the tool needs to be adjusted, the punchability is inferior, and No. 2-7 The number density of inclusions in the product plate exceeded the range of the present invention, the iron loss value was relatively high, and the magnetic properties were poor.
As shown above, a product plate with chemical components and inclusions within the scope of the present invention has a better iron loss value and punchability than a product plate with chemical components and inclusions outside the scope of the present invention. It was.
成分を表５に示す通りに種々変更した鋼を溶解し、アルミナ（Ａｌ２Ｏ３）と酸化鉄（Ｆｅ２Ｏ３）を質量比で１：１で混合した平均粒径０．８mmの酸化物粉末をワイヤーに被覆して３〜４ｋｇ／ｍｉｎの供給速度で鋳型内に供給し、溶鋼の吐出流量を３トン／ｍｉｎとして連続鋳造し、熱間圧延し、厚さ０．５ｍｍに冷間圧延し、８５０℃×３０秒の仕上げ焼鈍を施し、通常の無方向性電磁鋼板に塗布される有機成分と無機成分を含有する絶縁皮膜を塗布して製品板を作成した。 As shown in Table 5, steels with various changes were dissolved, and alumina (Al 2 O 3 ) and iron oxide (Fe 2 O 3 ) were mixed at a mass ratio of 1: 1. The product powder is coated on a wire and supplied into the mold at a supply rate of 3 to 4 kg / min, continuously cast with a molten steel discharge flow rate of 3 tons / min, hot rolled, and cold to a thickness of 0.5 mm. The product plate was produced by rolling and finishing annealing at 850 ° C. for 30 seconds, and applying an insulating film containing an organic component and an inorganic component applied to a normal non-oriented electrical steel sheet.
次に、製品板の直径が２μｍ以上２５μｍ以下の介在物について個数密度を光学顕微鏡により調査し、また、介在物組成をＳＥＭ−ＥＤＸにより分析した。また、製品板を高速打ち抜き機によりクリアランス０．１mmで２５cm長に打ち抜き、ＪＩＳ−Ｃ−２５５０に示すエプスタイン法で磁気特性を調査した。また、高速打ち抜き機によりクリアランス０．１mmで径１２mmの円形に打ち抜き加工し、打ち抜き荷重を測定した。さらに、連続打ち抜きを行い、打ち抜き後の鋼板のダレ高さを測定し、ダレ高さが板厚の１割（５０μｍ）となるまでの打ち抜き回数、及び１０５回連続打ち抜き後の工具の磨耗状態を調査した。また、打ち抜き破断面をＳＥＭ−ＥＤＸにより調査し、介在物組成を分析した。なお、打ち抜きに際して水溶性の潤滑油を用いた。 Next, the number density of the inclusions having a product plate diameter of 2 μm or more and 25 μm or less was examined by an optical microscope, and the inclusion composition was analyzed by SEM-EDX. Further, the product plate was punched to a length of 25 cm with a clearance of 0.1 mm using a high-speed punching machine, and the magnetic characteristics were investigated by the Epstein method shown in JIS-C-2550. Further, a punching process was performed with a high-speed punching machine into a circle having a clearance of 0.1 mm and a diameter of 12 mm, and the punching load was measured. Further, the continuous punching, the sag height of the steel sheet after punching is measured, the wear state of the sagging punching number up to a height of 1% of the thickness (50 [mu] m), and 10 5 times after successive punching tool investigated. Moreover, the punching fracture surface was investigated by SEM-EDX, and the inclusion composition was analyzed. A water-soluble lubricating oil was used for punching.
以上の結果を表６に示す。打ち抜き破断面の割れ起点には直径２μｍ以上２５μｍ以下の硬質介在物が観察され、それ以外の介在物は観察されなかった。また、ＲＥＭを添加したＮo.３−１は、介在物のサイズと個数密度が本発明の範囲内にあり、かつ生成した介在物が粒状単体のアルミナであり、鉄損値や打ち抜き性が良好な結果が得られた。一方、ＲＥＭ含有量が下限値を外れたＮo.３−２は、介在物のサイズと個数密度が本発明の範囲内にあったが、生成した介在物がＭｎＳに周囲を覆われたアルミナであり、鉄損値は良好であったが、打ち抜き性が劣る結果が得られた。また、Ｃａ添加を行ったＮo.３−３では、介在物のサイズと個数密度が本発明の範囲内にあったが、生成した介在物が延伸したＣａＳであり、打ち抜き性は良好であったが、鉄損値が劣る結果が得られた。 The results are shown in Table 6. Hard inclusions having a diameter of 2 μm or more and 25 μm or less were observed at the crack starting point of the punched fracture surface, and other inclusions were not observed. In addition, No. 3-1 to which REM is added has the inclusion size and number density within the range of the present invention, and the produced inclusion is a single granular alumina, which has good iron loss value and punchability. Results were obtained. On the other hand, No. 3-2 in which the REM content deviated from the lower limit value was an alumina in which the size and number density of inclusions were within the range of the present invention, but the generated inclusions were covered with MnS. Yes, the iron loss value was good, but the punching property was inferior. In No. 3-3 to which Ca was added, the size and number density of inclusions were within the scope of the present invention, but the produced inclusion was stretched CaS, and the punchability was good. However, the result that an iron loss value is inferior was obtained.
以上説明した通り、本発明に基づいて無方向性電磁鋼板中に内包される硬質介在物を適正に制御することにより、打ち抜き性が良く、工具寿命が延長でき、かつ打ち抜きによる磁気特性の劣化が少なく、品質に優れた無方向性電磁鋼板を提供できる。 As described above, by properly controlling the hard inclusions contained in the non-oriented electrical steel sheet according to the present invention, the punchability is good, the tool life can be extended, and the magnetic properties are deteriorated by punching. It is possible to provide a non-oriented electrical steel sheet with few and excellent quality.
Ａ 打ち抜き加工時の破断起点となる介在物の存在箇所
Ｂ 打ち抜き加工時の破断起点となる介在物
A Locations of inclusions that become the starting point of fracture during punching B Inclusions that become the starting point of fracture during punching
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| WO2017111549A1 (en) * | 2015-12-23 | 2017-06-29 | 주식회사 포스코 | Non-oriented electrical steel sheet and manufacturing method therefor |
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| JPH03104844A (en) * | 1989-09-18 | 1991-05-01 | Nippon Steel Corp | Nonoriented silicon steel sheet excellent in magnetic characteristics and its manufacture |
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| WO2014104444A1 (en) * | 2012-12-27 | 2014-07-03 | 주식회사 포스코 | Grain oriented electrical steel sheet having excellent core loss, and method for manufacturing same |
| KR101482354B1 (en) | 2012-12-27 | 2015-01-13 | 주식회사 포스코 | Grain-oriented electrical steel having excellent magnetic properties |
| US9847158B2 (en) | 2012-12-27 | 2017-12-19 | Posco | Grain oriented electrical steel sheet having excellent core loss, and method for manufacturing same |
| US10109405B2 (en) | 2012-12-27 | 2018-10-23 | Posco | Grain oriented electrical steel sheet having excellent core loss, and method for manufacturing same |
| WO2017111549A1 (en) * | 2015-12-23 | 2017-06-29 | 주식회사 포스코 | Non-oriented electrical steel sheet and manufacturing method therefor |
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