JP4218136B2 - Non-oriented electrical steel sheet with high magnetic flux density and low iron loss and method for producing the same - Google Patents
Non-oriented electrical steel sheet with high magnetic flux density and low iron loss and method for producing the same Download PDFInfo
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Description
【０００１】
【発明の属する技術分野】
本発明は、電気機器の鉄心として広く用いられる高磁束密度で低鉄損の無方向性電磁鋼板およびその製造方法に関するものである。
【０００２】
【従来の技術】
無方向性電磁鋼板の内で、Si含有量が１％（wt％を意味する）以下程度の比較的低Siの無方向性電磁鋼板が、発電機、モータや小型変圧器等として電気機器に広く用いられている。省エネルギーの観点より電気機器の高効率化が要望されており、磁気特性として特に低鉄損で高磁束密度の無方向性電磁鋼板が求められている。
【０００３】
一般に、無方向性電磁鋼板において、鉄損を低下させるためには結晶粒度を大きくすることが重要であり、このとき酸化物、硫化物、窒化物の生成が粒成長に大きく影響する。一方、磁束密度は、Si、Al等の添加により低下するため、高磁束密度の無方向性電磁鋼板を製造するためには、合金元素の量を低下する必要がある。また、析出物の低下による結晶粒成長性の向上のためには、脱硫によりＳを低下させ、出鋼時のＮピックアップの防止、ＲＨ脱ガスでの脱窒処理によりＮを低下させている。
【０００４】
酸化物を低減させる方法としてしては、Al、Si等で脱酸する方法が一般的に知られている。さらに、微細なAlN の析出を防止するために、従来よりAlを0.2 ％以上とし、介在物をAl2O3 とするとともにAlN を粗大化させる技術が知られている。ただし、高磁束密度を達成するためには、合金元素を低下させる必要があり、Alを0.2 ％以上添加することは問題となる。
【０００５】
そこで、Alを0.001%程度の低濃度に調整し、AlN の析出を防止する方法も知られている。このとき問題となるのは、SiO2-MnO-Al2O3系の延性介在物を生成することである。このため、特開平1-152239号公報には、介在物組成をMnO/(SiO2+MnO+Al2O3)≦15％、SiO2/(SiO2+MnO+Al2O3) ≧75％に制御し、介在物組成を非延性にする方法が示されている。
【０００６】
また、特開平10-102219 号公報には、介在物の重量割合を、MnO/SiO2≦0.25、Al2O3/SiO2=0.1〜1 、SiO2/(SiO2+MnO+Al2O3)<0.75にすることにより連続鋳造時のノズル詰まりを防止しつつ焼鈍時の粒成長性に優れた電磁鋼板を溶製する方法が示されている。
さらに、介在物形態を変化させるため、特開平3-126845号公報には、Ca/S=0.1〜1.5 となるようにCaを添加し、ＳをCaS とするとともに、介在物をAl2O3-CaO 系に制御する技術や、特開平10-212555 号公報には、Mgを添加することで介在物組成を、MgO を８％以上、(SiO2+MgO)を60％以上に制御する方法が示されている。
【０００７】
【発明が解決しようとする課題】
前述のように従来よりAlを0.2 ％以上とし、介在物をAl2O3 とするとともにAlN を粗大化させる技術が知られているが、このような方法では、高磁束密度を達成するためには、合金元素を低下させる必要があり、Alを0.2 ％以上添加することは、磁束密度の低下を引き起こすという問題があった。
【０００８】
また、Alを0.001 ％程度の低濃度に調整し、AlN の析出を防止する方法において問題となるのは、SiO2-MnO-Al2O3系の延性介在物を生成することである。このため、特開平1-152239号公報に示される方法では介在物形態を完全に非延性にすることができず、鉄損の低下が図れないばかりでなく、SiO2濃度を高くし過ぎると、介在物の酸素濃度が高くなり、連鋳機においてノズル詰まりを引き起こし、安定製造ができないという問題があった。
【０００９】
また、特開平10-102219 号公報の方法では、連続鋳造時のノズル詰まりは防止できても、熱間圧延時における介在物の非延性化は防止できず、結果的に鉄損を低位に安定させることができなかった。
さらに、介在物形態を変化させるための技術として、特開平3-126845号や特開平10-212555 号公報に示された方法でも介在物の延性化が十分に防止できていないという問題があった。
【００１０】
【課題を解決するための手段】
本発明は、前記課題を解決するために、介在物を非延性化し、結晶粒の成長性を向上することができる高磁束密度低鉄損の無方向性電磁鋼板およびその製造方法を提供することを目的とするものである。
前記目的を達成するための請求項１記載の本発明は、重量％で、Ｃ：0.01％以下、Si：0.01〜１％、Mn：1.5 ％以下、Ｐ：O.15％以下、Ｓ：0.01％以下、sol.Al：0.0010％以下、残部はFeおよび不可避的不純物を含み、介在物の組成がMgO :10 ％以上、MgO/Al2O3 :0.2〜1.0 、SiO2/Al2O3:0.43 〜2.3 となることを特徴とする無方向性電磁鋼板である。
【００１１】
請求項２記載の本発明は、一次精錬炉より出鋼した溶鋼を、真空脱ガス装置により脱炭処理を行った後、該溶鋼へのAl添加による予備脱酸により溶存酸素濃度を50〜150ppmとなし、次いでSiおよびMg、またはSiおよびMg合金を添加することにより請求項１記載の成分および介在物組成とすることを特徴とする無方向性電磁鋼板の製造方法である。
【００１２】
請求項３記載の本発明は、一次精錬炉より出鋼した溶鋼を、真空脱ガス装置により脱炭処理を行った後、該溶鋼へのAl添加による予備脱酸により溶存酸素濃度を50〜150ppmとなし、次いでSi添加により成分調整を行ってから、取鍋内の溶鋼にMgまたはMg合金を添加することにより請求項１記載の成分および介在物組成とすることを特徴とする無方向性電磁鋼板の製造方法である。
【００１３】
【発明の実施の形態】
本発明において介在物の延性能を検討した結果、SiO2系およびMgO-SiO2系が最も延性介在物になりにくいことを発見した。しかし、SiO2濃度の高い介在物を生成させることは、前に述べたように介在物酸素濃度が高くなり、連鋳機においてノズル詰まりを起こして製造が非常に不安定となり、鉄損の低い電磁鋼板を安定的に製造することができない。
【００１４】
これに対して、Al予備脱酸後のSi添加時またはSi添加後に酸素と親和力の強いMgを添加するとMgO-SiO2-Al2O3系の介在物が生成し、介在物個数を減少させるとともに、残存する介在物がMgO を含有することにより融点を1500℃以上に上昇できる。融点の高い非延性の介在物とすることにより粒成長性が向上するので、鋳片の圧延により得られた電磁鋼板の鉄損は低位安定したものとなる。このように本発明では、介在物組成をMgO-SiO2系に制御することによって、延性介在物の生成が抑制され、低鉄損で高磁束密度の電磁鋼板を製造できる。
【００１５】
本発明の製造方法を説明する。
本発明の電磁鋼板を製造する鋼の溶製は、転炉、電気炉等の通常の溶製方法で製造され、目標とする最終の溶鋼組成を得る。例えば転炉から出鋼したＣは0.03〜0.15％、Mn:0.01 〜0.1 ％、Si:0.3％、Ｐ:0.005％〜0.10％であればよい。転炉から出鋼された溶鋼はＲＨ脱ガス装置等により0.01気圧以下で真空処理して脱炭され、溶鋼中のＣ含有量を0.01％以下とする。ここで溶鋼中の酸素含有量が増加するのを防止するため、Ｃ含有量を0.0005％以上とするのが好ましい。
【００１６】
真空脱炭処理された溶鋼へのAl添加による予備脱酸により溶存酸素濃度を50〜150ppmとする。ここで、溶存酸素濃度の下限を50ppm としたのは、Alにより50ppm 未満まで予備脱酸処理を行うとAlN の発生で延性が阻害されやすく、一方、150ppmを超えてのAlによる予備脱酸は多量のAl2O3 が発生し、介在物が多くなり過ぎる他、操業が不安定になるという問題がある。このようにして予備脱酸処理した脱ガス槽内の溶鋼に強力な脱酸能のあるSiとMg、またはSiとMg合金を添加することにより、目標とする最終の溶鋼組成を得る。もしくは、同様の手順でAl添加による予備脱酸を行った後、取鍋内の溶鋼にまずSiを添加して脱酸し、次にMgまたはMg合金を添加することにより目標とする最終の溶鋼組成を得るようにすることもできる。
【００１７】
その後、連続鋳造法または分塊圧延法によりスラブとした後、常法に従う熱間圧延法で板厚2.0 〜3.0mm 程度の熱延板に仕上げる。なお、板厚はこの寸法に限定されるものではない。次いで、必要に応じて製品の集合組織改善のための熱延板の焼鈍を行った後、冷間圧延により所定の板厚とし、さらに最終焼鈍を行いその後、公知の方法で絶縁皮膜を生成する。
【００１８】
例えば、表１に示す組成になる本発明の実施例および比較例に係る無方向性電磁鋼板用スラブを転炉−真空脱ガス（ＲＨ）−連続鋳造工程により製造した。Mgの添加は、真空脱ガスにおいて脱炭処理を行った後、AlおよびMnを添加し、所定の成分としてSi-Mg 合金を添加したものと、ＲＨ処理後の取鍋内に金属被覆Mg（以下、Mgワイヤとする）を使用して行った。次いで、1150℃に加熱後、熱延により2.0mm 厚さとした後、冷延して0.5mm 厚とし、750 ℃、10秒の仕上げ焼鈍後に絶縁皮膜を被成した。さらに、750 ℃、２時間の歪取焼鈍を施した。かくして得られた製品の成分歪取焼鈍後の粒径および磁気特性: JISC2550に規定のエプスタイン試験法による鉄損Ｗ15/50 と磁束密度Ｂについて調べた結果を表１に併記する。
【００１９】
【表１】
表１において本発明の実施例に係る鋼の化学組成は、下記の範囲に調整してある。
Ｃ：Ｃは鉄損を高める有害成分で、0.01％を超えるとＣの析出にりより磁気時効が著しくなり、磁気特性を劣化させるので少ないほど好ましく、電磁鋼板としての特性を満たすために、Ｃ含有量の上限を0.01％とする。
【００２１】
Si：鋼を脱酸するため、および鋼の電気抵抗を高めて鉄損を低減するために用いられるSiは、脱酸効果を得るために0.01％以上を含有させる。一方、Si含有量が増すにつれて磁束密度が低下するので、その上限を１％とする。
Mn：Mnは鋼板の硬度を増加させ、鉄心に加工するときの鋼板の打抜き性および固有抵抗を高めて鉄損を下げる効果があるが、Mn含有量が増すと延性に富むMnO 系の介在物が増すおそれがある。MnO 系介在物の生成を抑制するためにMn含有量の上限を1.5 ％とする。
【００２２】
Ｐ：電気抵抗を高めて鉄損を改善し、鋼板の硬度を増し、打抜き性を改良するが、Ｐを過度に含有させると鋼が脆化するので、0.15％以下に抑える。
Ｓ：Ｓは0.01％を超えるとMnS の析出が生じ易く、焼鈍時の結晶粒の成長を妨げるので少ないほうがよく0.01％以下とする。
Al：Alは健全な鋳片を得るための溶鋼の脱酸剤としての役割と、介在物中のAl2O3 含有量を制御する役割を持っている。Al添加により生じる脱酸生成物の一部は浮上するが、残余は鋼中で酸化物系介在物を形成し、さらに過剰のAlはsol.Alとして鋼中に残存する。sol.Alは、主に微細な析出物であるAlN として存在する。AlN の量が増すと結晶粒の成長や磁壁移動の障害となる。このため、sol.Alは少ないのが好ましく、その含有量の上限を0.0010％とする。
【００２３】
なお、Mgの添加に用いる合金の種類は特定するものではないが、所定の成分としたSi-Mg 合金、Fe-Mg 合金、Fe-Si-Mg合金等が好適であり、合金の形態はMg源金属を塊状もしくはワイヤ状にして用いるのが取扱いに便利である。Mgは必ずしも鋼板に残存させる必要はないが、ＳやＮと析出物を形成するのを避けるためには0.003 ％以下にするのが好ましい。また、鋼中に溶存する酸素と介在物中の酸素からなる全酸素量は、0.01％以下にするのが好適である。上記以外の元素はFeおよび不可避的不純物である。
【００２４】
また、表１における本発明の実施例に係る介在物の組成は上記の通り、MgO :10 ％以上、MgO/Al2O3 :0.2〜1.0 、SiO2/Al2O3:0.43 〜2.3 にする必要がある。 MgO ：酸化物系介在物の融点を高くし、熱間圧延時に介在物を非延性にするには、介在物組成を鋼板中の酸化物系介在物の総量に対する重量比でMgO を10％以上にする必要がある。MgO が10% 未満であるとMgによる脱酸が不十分となり、また介在物の融点が低くなり易く、熱間圧延で介在物が延ばされ、歪み取り焼鈍時の結晶粒成長を阻害する。
【００２５】
MgO/Al2O3 ：表１に示すように、介在物中のAl2O3 に対するMgO の重量比MgO/Al2O3 が0.2 に満たない比較例２、３、４および７の場合には、介在物の非延性が阻害され鋼板の歪取焼鈍後の結晶粒径が小さく、鉄損Ｗ15/50 が大きくなる。また、MgO/Al2O3 が1.0 を超える比較例１、５および６の場合にも、介在物析出量が増加するため、鋼板の歪取焼鈍後の結晶粒径が小さくなとともに鉄損Ｗ15/50 が大きくなる。これに対して、MgO/Al2O3 を0.43〜2.3 範囲にする本発明の実施例１〜８の場合には、比較例１〜７より格段に鋼板の歪取焼鈍後の結晶粒の粒径を大きくでき、鉄損Ｗ15/50 が低位に安定するとともに、磁束密度Ｂ50を1.77〜1.80(T) レベルに保持でき、良好な磁気特性の無方向性電磁鋼板が得られる。
【００２６】
SiO2/Al2O3: 介在物中のAl2O3 に対するSiO2の重量比SiO2/Al2O3が0.43未満となってSiO2が少ない場合、相対的にAl2O3 が増すので、微細な単体Al2O3 の介在物が多くなって結晶粒の成長が阻害される。逆に、SiO2/Al2O3が2.3 を超えてAl2O3 が低くなりすぎるとSiO2系の微細析出物が生成され、結晶粒の成長や磁気特性に悪影響を及ぼす。また、SiO2の比率が高くなると、連続鋳造時にノズルが詰まり易くなる。このため、結晶粒の成長を確保して所望の磁気特性を得るには、SiO2/Al2O3を0.43〜2.3 範囲にする必要がある。
【００２７】
表１より明らかなように、本発明の実施例に係る無方向性電磁鋼板は、比較例よりも格段に歪み取り焼鈍後の結晶粒成長性に優れ、鉄損が低位に安定するとともに磁束密度の高い製品を製造することができる。
【００２８】
【発明の効果】
以上、説明したように本発明の高磁束密度低鉄損の無方向性電磁鋼板は、重量％で、Ｃ：0.01％以下、Si：0.01〜１％、Mn：1.5 ％以下、Ｐ：O.15％以下、Ｓ：0.01％以下、sol.Al：0.0010％以下、残部はFeおよび不可避的不純物を含み、介在物の組成をMgO :10 ％以上、MgO/Al2O3 :0.2〜1.0 、SiO2/Al2O3:0.43 〜2.3 にするので、熱間圧延時に介在物が非延性化され、無方向性電磁鋼板の結晶粒成長性が向上できる。その結果、鉄損が低く、磁束密度の高い無方向性電磁鋼板を安定して製造することができる。[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a non-oriented electrical steel sheet having a high magnetic flux density and a low iron loss, which is widely used as an iron core of electrical equipment, and a method for producing the same.
[0002]
[Prior art]
Among non-oriented electrical steel sheets, non-oriented electrical steel sheets with a relatively low Si content of less than 1% (meaning wt%) are used in electrical equipment as generators, motors, small transformers, etc. Widely used. From the viewpoint of energy saving, there is a demand for higher efficiency of electrical equipment, and non-oriented electrical steel sheets with particularly low iron loss and high magnetic flux density are required as magnetic properties.
[0003]
In general, in a non-oriented electrical steel sheet, it is important to increase the crystal grain size in order to reduce the iron loss. At this time, the formation of oxides, sulfides, and nitrides greatly affects the grain growth. On the other hand, since the magnetic flux density is reduced by the addition of Si, Al, etc., it is necessary to reduce the amount of alloy elements in order to produce a high magnetic flux density non-oriented electrical steel sheet. Further, in order to improve the crystal grain growth by reducing the precipitates, S is reduced by desulfurization, and N is reduced by prevention of N pickup at the time of steel output and denitrification treatment by RH degassing.
[0004]
As a method for reducing oxides, a method of deoxidizing with Al, Si or the like is generally known. Furthermore, in order to prevent the precipitation of fine AlN, a technique is conventionally known in which Al is 0.2% or more, inclusions are Al 2 O 3 and AlN is coarsened. However, in order to achieve a high magnetic flux density, it is necessary to lower the alloy elements, and adding 0.2% or more of Al becomes a problem.
[0005]
Therefore, a method is known in which Al is adjusted to a low concentration of about 0.001% to prevent precipitation of AlN. The problem at this time is the generation of ductile inclusions of the SiO 2 —MnO—Al 2 O 3 system. For this reason, JP-A-1-152239 discloses that the inclusion composition is MnO / (SiO 2 + MnO + Al 2 O 3 ) ≦ 15%, SiO 2 / (SiO 2 + MnO + Al 2 O 3 ) ≧ 75 %, And a method of making the inclusion composition non-ductile is shown.
[0006]
JP-A-10-102219 discloses the weight ratio of inclusions as MnO / SiO 2 ≦ 0.25, Al 2 O 3 / SiO 2 = 0.1 to 1, SiO 2 / (SiO 2 + MnO + Al 2 O 3 ) A method of melting an electromagnetic steel sheet excellent in grain growth during annealing while preventing nozzle clogging during continuous casting by setting <0.75 is shown.
Furthermore, in order to change the form of inclusions, Japanese Patent Application Laid-Open No. 3-128845 discloses that Ca is added so that Ca / S = 0.1 to 1.5, S is changed to CaS, and inclusions are made of Al 2 O 3. -CaO system control technology and Japanese Patent Application Laid-Open No. 10-212555 include a method for controlling inclusion composition by adding Mg to 8% or more and (SiO 2 + MgO) to 60% or more. It is shown.
[0007]
[Problems to be solved by the invention]
As mentioned above, there is a known technology that makes Al 0.2% or more and inclusions Al 2 O 3 and coarsens AlN as described above. However, with such a method, in order to achieve a high magnetic flux density, However, it is necessary to lower the alloy elements, and adding 0.2% or more of Al has a problem of causing a decrease in magnetic flux density.
[0008]
In addition, a problem in the method of adjusting the Al concentration to a low concentration of about 0.001% and preventing the precipitation of AlN is to generate a ductile inclusion of SiO 2 —MnO—Al 2 O 3 system. For this reason, in the method shown in JP-A-1-152239, the inclusion form cannot be made completely non-ductile, not only can the iron loss be reduced, but if the SiO 2 concentration is too high, There was a problem that the oxygen concentration of the inclusions became high, causing nozzle clogging in the continuous casting machine and making stable production impossible.
[0009]
Further, in the method disclosed in Japanese Patent Laid-Open No. 10-102219, even if nozzle clogging during continuous casting can be prevented, inclusion non-ductility during hot rolling cannot be prevented, resulting in stable iron loss at a low level. I couldn't let you.
Further, as a technique for changing the form of inclusions, there is a problem that the ductility of inclusions cannot be sufficiently prevented even by the methods disclosed in Japanese Patent Laid-Open Nos. 3-128845 and 10-212555. .
[0010]
[Means for Solving the Problems]
In order to solve the above-mentioned problems, the present invention provides a non-oriented electrical steel sheet with high magnetic flux density and low iron loss, which can make inclusions non-ductile and improve crystal grain growth, and a method for producing the same. It is intended.
In order to achieve the above object, the present invention according to claim 1 is, by weight percent, C: 0.01% or less, Si: 0.01 to 1%, Mn: 1.5% or less, P: O. 15% or less, S: 0.01 %, Sol.Al: 0.0010% or less, the balance contains Fe and inevitable impurities, the composition of inclusions is MgO: 10% or more, MgO / Al 2 O 3 : 0.2-1.0, SiO 2 / Al 2 O 3 : is a non-oriented electrical steel sheet shall be the equal to an 0.43 to 2.3.
[0011]
In the present invention according to claim 2, after the molten steel produced from the primary refining furnace is decarburized by a vacuum degassing apparatus, the dissolved oxygen concentration is reduced to 50 to 150 ppm by preliminary deoxidation by adding Al to the molten steel. ungated, then it is Si and Mg or method of manufacturing a non-oriented electrical steel sheet you characterized in that the components and composition of inclusions of claim 1, wherein by the addition of Si and Mg alloys.
[0012]
According to the third aspect of the present invention, the molten steel produced from the primary smelting furnace is decarburized by a vacuum degassing apparatus, and then the dissolved oxygen concentration is reduced to 50 to 150 ppm by preliminary deoxidation by adding Al to the molten steel. ungated, then either performing component adjustment et by Si addition, non-oriented you characterized in that the components and composition of inclusions of claim 1, wherein by the addition of Mg or Mg alloy into molten steel in the ladle It is a manufacturing method of an electrical steel sheet.
[0013]
DETAILED DESCRIPTION OF THE INVENTION
Results of examining the extended performance of inclusions in the present invention, have found that the SiO 2 system and MgO-SiO 2 system less likely the most ductile inclusions. However, generating inclusions with a high SiO 2 concentration increases the oxygen concentration of inclusions as described above, causing nozzle clogging in the continuous casting machine, making the production extremely unstable, and reducing iron loss. An electromagnetic steel sheet cannot be manufactured stably.
[0014]
On the other hand, inclusion of MgO-SiO 2 -Al 2 O 3 inclusions during the addition of Si after Al preliminary deoxidation or after addition of Si, which has strong affinity for oxygen, reduces the number of inclusions At the same time, the melting point can be raised to 1500 ° C. or higher by the inclusion of the remaining inclusions containing MgO. Since grain growth is improved by using a non-ductile inclusion with a high melting point, the iron loss of the electrical steel sheet obtained by rolling the slab becomes low and stable. Thus, in the present invention, by controlling the inclusion composition to be MgO—SiO 2 , the production of ductile inclusions is suppressed, and an electrical steel sheet having a low iron loss and a high magnetic flux density can be manufactured.
[0015]
The production method of the present invention will be described.
The steel for producing the electromagnetic steel sheet according to the present invention is produced by a normal melting method such as a converter or an electric furnace to obtain a target final molten steel composition. For example, C produced from the converter may be 0.03 to 0.15%, Mn: 0.01 to 0.1%, Si: 0.3%, P: 0.005% to 0.10%. The molten steel discharged from the converter is decarburized by vacuum treatment at 0.01 atm or less by an RH degassing apparatus or the like, so that the C content in the molten steel is 0.01% or less. Here, in order to prevent the oxygen content in the molten steel from increasing, the C content is preferably set to 0.0005% or more.
[0016]
And 50~150ppm dissolved oxygen concentration by preliminary deoxidation by adding Al to the vacuum decarburization treated dissolved steel. Here, the lower limit of the dissolved oxygen concentration was set to 50 ppm. When pre-deoxidation treatment with Al was performed to less than 50 ppm, ductility was liable to be inhibited by the generation of AlN, whereas pre-deoxidation with Al exceeding 150 ppm was not There is a problem that a large amount of Al 2 O 3 is generated, the inclusions become excessive, and the operation becomes unstable. By adding Si and Mg or Si and Mg alloy having strong deoxidizing ability to the molten steel in the degassing tank preliminarily deoxidized in this way, a final final molten steel composition is obtained. Alternatively, after pre-deoxidation by adding Al in the same procedure, first add Si to the molten steel in the ladle to deoxidize, and then add Mg or Mg alloy to the final final molten steel A composition can also be obtained.
[0017]
Thereafter, the slab is formed by a continuous casting method or a block rolling method, and then finished into a hot rolled sheet having a thickness of about 2.0 to 3.0 mm by a hot rolling method according to a conventional method. The plate thickness is not limited to this dimension. Then, if necessary, after annealing the hot-rolled sheet to improve the texture of the product, it is cold-rolled to a predetermined sheet thickness, further subjected to final annealing, and then an insulating film is generated by a known method .
[0018]
For example, slabs for non-oriented electrical steel sheets according to Examples and Comparative Examples of the present invention having the compositions shown in Table 1 were manufactured by a converter-vacuum degassing (RH) -continuous casting process. Addition of Mg includes decarburization in vacuum degassing, then Al and Mn, Si-Mg alloy added as a predetermined component, and metal-coated Mg (in the ladle after RH treatment) Hereinafter, Mg wire was used. Next, after heating to 1150 ° C., the thickness was 2.0 mm by hot rolling, and then cold-rolling to 0.5 mm thickness, and an insulating film was formed after finishing annealing at 750 ° C. for 10 seconds. Further, strain relief annealing was performed at 750 ° C. for 2 hours. The particle diameter and magnetic properties of the product thus obtained after component strain relief annealing are shown in Table 1 together with the results of investigation on iron loss W15 / 50 and magnetic flux density B by the Epstein test method specified in JISC2550.
[0019]
[Table 1]
In Table 1, the chemical composition of the steel according to the example of the present invention is adjusted to the following range.
C: C is a harmful component that increases iron loss. If it exceeds 0.01%, the magnetic aging becomes more remarkable due to the precipitation of C, and the magnetic properties are deteriorated. The upper limit of the content is 0.01%.
[0021]
Si: Si used for deoxidizing steel and increasing the electric resistance of steel to reduce iron loss contains 0.01% or more in order to obtain a deoxidizing effect. On the other hand, the magnetic flux density decreases as the Si content increases, so the upper limit is made 1%.
Mn: Mn increases the hardness of the steel sheet and has the effect of reducing the iron loss by increasing the punchability and specific resistance of the steel sheet when processed into an iron core. However, if the Mn content increases, the MnO-based inclusions are rich in ductility. May increase. In order to suppress the formation of MnO inclusions, the upper limit of Mn content is 1.5%.
[0022]
P: Increases electric resistance to improve iron loss, increases the hardness of the steel sheet, and improves punchability. However, if P is excessively contained, the steel becomes brittle, so it is suppressed to 0.15% or less.
S: If S exceeds 0.01%, MnS precipitates easily and hinders the growth of crystal grains during annealing.
Al: Al has a role as a deoxidizer of molten steel to obtain a sound slab and a role of controlling the content of Al 2 O 3 in inclusions. A part of the deoxidation product generated by the addition of Al floats, but the remainder forms oxide inclusions in the steel, and excess Al remains in the steel as sol.Al. sol.Al exists mainly as AlN, which is a fine precipitate. As the amount of AlN increases, it becomes an obstacle to crystal grain growth and domain wall motion. For this reason, it is preferable that there is little sol.Al, and the upper limit of the content is made 0.0010%.
[0023]
The type of alloy used for the addition of Mg is not specified, but Si-Mg alloy, Fe-Mg alloy, Fe-Si-Mg alloy, etc. with the prescribed components are suitable, and the form of the alloy is Mg It is convenient to handle the source metal in the form of a lump or wire. Mg is not necessarily left in the steel sheet, but is preferably 0.003% or less in order to avoid the formation of precipitates with S and N. Moreover, it is preferable that the total oxygen amount consisting of oxygen dissolved in the steel and oxygen in the inclusions is 0.01% or less. Elements other than the above are Fe and inevitable impurities.
[0024]
In addition, the composition of inclusions according to the examples of the present invention in Table 1 is MgO: 10% or more, MgO / Al 2 O 3 : 0.2 to 1.0, and SiO 2 / Al 2 O 3 : 0.43 to 2.3 as described above. There is a need to. MgO: To increase the melting point of oxide inclusions and make the inclusions non-ductile during hot rolling, the inclusion composition is 10% or more in terms of weight ratio with respect to the total amount of oxide inclusions in the steel sheet. It is necessary to. If MgO is less than 10%, deoxidation by Mg becomes insufficient, and the melting point of inclusions tends to be lowered, the inclusions are extended by hot rolling, and the grain growth during strain relief annealing is inhibited.
[0025]
MgO / Al 2 O 3 : As shown in Table 1, in the case of Comparative Examples 2, 3, 4 and 7, the MgO / Al 2 O 3 weight ratio of MgO to Al 2 O 3 in the inclusion is less than 0.2. In this case, the non-ductility of inclusions is hindered, the crystal grain size after strain relief annealing of the steel sheet is small, and the iron loss W15 / 50 is large. Also, in the cases of Comparative Examples 1, 5, and 6 in which MgO / Al 2 O 3 exceeds 1.0, the amount of inclusion precipitation increases, so that the crystal grain size after strain relief annealing of the steel sheet becomes smaller and the iron loss W15 / 50 increases. On the other hand, in the case of Examples 1 to 8 of the present invention in which MgO / Al 2 O 3 is in the range of 0.43 to 2.3, the grains of the crystal grains after the strain relief annealing of the steel plate are more marked than Comparative Examples 1 to 7. The diameter can be increased, the iron loss W15 / 50 is stabilized at a low level, the magnetic flux density B50 can be maintained at a level of 1.77 to 1.80 (T), and a non-oriented electrical steel sheet having good magnetic properties can be obtained.
[0026]
SiO 2 / Al 2 O 3: If the weight ratio SiO 2 / Al 2 O 3 of SiO 2 to Al 2 O 3 in inclusions is small SiO 2 becomes less than 0.43, increases relatively Al 2 O 3 Therefore, the inclusion of fine single-piece Al 2 O 3 increases and the growth of crystal grains is hindered. On the other hand, if SiO 2 / Al 2 O 3 exceeds 2.3 and Al 2 O 3 becomes too low, SiO 2 -based fine precipitates are generated, which adversely affects crystal growth and magnetic properties. Further, when the ratio of SiO 2 is increased, the nozzle is easily clogged during continuous casting. For this reason, in order to secure the growth of crystal grains and obtain desired magnetic characteristics, it is necessary to make SiO 2 / Al 2 O 3 in the range of 0.43 to 2.3.
[0027]
As is clear from Table 1, the non-oriented electrical steel sheets according to the examples of the present invention are much more excellent in crystal grain growth after strain relief annealing than the comparative examples, the iron loss is stabilized at a low level, and the magnetic flux density. High-quality products can be manufactured.
[0028]
【The invention's effect】
As described above, the non-oriented electrical steel sheet having high magnetic flux density and low iron loss according to the present invention is C: 0.01% or less, Si: 0.01-1%, Mn: 1.5% or less, P: O. 15% or less, S: 0.01% or less, sol.Al: 0.0010% or less, the balance contains Fe and inevitable impurities, and the composition of inclusions is MgO: 10% or more, MgO / Al 2 O 3 : 0.2-1.0, Since SiO 2 / Al 2 O 3 : 0.43 to 2.3, inclusions are made non-ductile during hot rolling, and the crystal grain growth of the non-oriented electrical steel sheet can be improved. As a result, a non-oriented electrical steel sheet with low iron loss and high magnetic flux density can be stably produced.
Claims (3)
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| JP17783499A JP4218136B2 (en) | 1999-06-24 | 1999-06-24 | Non-oriented electrical steel sheet with high magnetic flux density and low iron loss and method for producing the same |
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| JP17783499A JP4218136B2 (en) | 1999-06-24 | 1999-06-24 | Non-oriented electrical steel sheet with high magnetic flux density and low iron loss and method for producing the same |
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Cited By (2)
| Publication number | Priority date | Publication date | Assignee | Title |
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| WO2018097006A1 (en) | 2016-11-25 | 2018-05-31 | Ｊｆｅスチール株式会社 | Non-oriented electrical steel sheet and manufacturing method therefor |
| WO2019225529A1 (en) | 2018-05-21 | 2019-11-28 | Ｊｆｅスチール株式会社 | Non-oriented electromagnetic steel sheet and method for manufacturing same |
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| JP4718749B2 (en) * | 2002-08-06 | 2011-07-06 | Ｊｆｅスチール株式会社 | High magnetic flux density non-oriented electrical steel sheet for rotating machine and member for rotating machine |
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| WO2018097006A1 (en) | 2016-11-25 | 2018-05-31 | Ｊｆｅスチール株式会社 | Non-oriented electrical steel sheet and manufacturing method therefor |
| KR20190077025A (en) | 2016-11-25 | 2019-07-02 | 제이에프이 스틸 가부시키가이샤 | Non-oriented electrical steel sheet and manufacturing method thereof |
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| WO2019225529A1 (en) | 2018-05-21 | 2019-11-28 | Ｊｆｅスチール株式会社 | Non-oriented electromagnetic steel sheet and method for manufacturing same |
| KR20210003908A (en) | 2018-05-21 | 2021-01-12 | 제이에프이 스틸 가부시키가이샤 | Non-oriented electrical steel sheet and its manufacturing method |
| US11649532B2 (en) | 2018-05-21 | 2023-05-16 | Jfe Steel Corporation | Non-oriented electrical steel sheet and method of producing same |
| US11946123B2 (en) | 2018-05-21 | 2024-04-02 | Jfe Steel Corporation | Method of producing a non-oriented electrical steel sheet |
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