JP4240642B2 - Manufacturing method of unidirectional electrical steel sheet - Google Patents

Description

【００１５】
【表２】

【００１６】
表１および表２に示したとおり、珪素鋼板の表面に直接、テルルおよび／またはビスマスを含む無機化合物を塗布した場合、および焼鈍分離剤中に混入させて鋼板表面に塗布した場合のいずれにおいても、従来のように、化学的処理および磁区細分化処理をそれぞれ単独で実施した場合の相和効果よりも一段と優れた鉄損改善効果が得られているのが注目される。
【００１７】
上述したとおり、この発明に従い、化学的処理技術と磁区細分化技術とを組み合わせることによって、極めて低い鉄損が得られる理由は、図１(a), (b), (c) に模式図で比較して示すように、従来の状態(c) では、BiやTeの塗布位置がゴス方位の２次再結晶核が発生する位置から離れているのに対し、本発明の場合(a),(b）には、BiやTeの塗布位置が２次再結晶核の発生位置に近づくため、これらの元素によるインヒビタ−効果が一層効果的に発揮されることによるためと考えられる。
従って、図１(b) に示したように、TeやBiの無機化合物を焼鈍分離剤中に添加するよりも、同図(a) に示したように、TeやBiの無機化合物を水溶液中に微量添加して鋼板表面に直接付着させるようにすることが一層効果的であり、より好ましい形態といえる。
【００１８】
【作用】
本発明の素材である珪素鋼板としては、従来公知の成分組成いずれもが適合するが、代表組成を掲げると次のとおりである。
Ｃ：0.01〜0.08wt％
Ｃは、0.01wt％より少ないと熱延集合組織の抑制が不十分となって大きな伸長粒が形成されるため磁気特性の劣化を招き、一方0.08wt％より多いと脱炭工程で脱炭に時間がかかり経済的でないので、0.01〜0.08wt％程度とするのが好ましい。
【００１９】
Si：2.0 〜4.0wt ％
Siは、 2.0wt％より少ないと十分な電気抵抗が得られないため渦電流損が増大して鉄損の劣化を招き、一方 4.0wt％より多いと冷延の際に脆性割れが生じ易くなるので、 2.0〜4.0 wt％程度とすることが好ましい。
【００２０】
Mn：0.01〜0.2 wt％
Mnは、一方向性珪素鋼板の２次再結晶を左右する分散析出相としてのMnＳあるいはMnSeを決定する重要な成分である。Mn量が0.01wt％を下回ると２次再結晶を生じさせるのに必要なMnＳ等の絶対量が不足し、不完全２次再結晶を起こすと同時に、ブリスタ−と呼ばれる表面欠陥が増大する。一方、 0.2wt％を超えると、スラブ加熱等においてMnＳ等の解離固溶が行われたとしても、熱延時に析出する分散析出相が粗大化し易く、抑制剤として望まれる最適サイズ分布が損なわれて磁気特性が劣化するので、Mnは0.01〜0.2 wt％程度とすることが好ましい。
【００２１】
Ｓ：0.008 〜0.1 wt％、Se：0.003 〜0.1 wt％
ＳおよびSeはいずれも、 0.1wt％以下、中でもＳは 0.008〜0.1 wt％、またSeは 0.003〜0.1 wt％の範囲とすることが好ましい。というのは、これらが 0.1wt％を超えると熱間および冷間加工性が劣化し、一方それぞれ下限値に満たないとMnＳ、MnSeとしての1 次粒成長抑制機能に格別の効果を生じないからである。
その他、インヒビタ−として従来公知のAl, Sb, Cu, Sn, ＢおよびＮ等を複合添加することは、本発明の効果を妨げるものではない。
【００２２】
次に、本発明に従う超低鉄損一方向性珪素鋼板の製造工程について説明する。
まず、素材を溶製するには、ＬＤ転炉、電気炉、平炉、その他公知の製鋼炉を用い得ることは勿論のこと、真空溶解やＲＨ脱ガス処理を併用することもできる。
本発明に従い、素材中に含有されるＳ、Seあるいはその他の１次粒成長抑制剤を溶鋼中に微量添加する方法としては、従来公知の何れの方法を用いても良く、例えばＬＤ転炉、ＲＨ脱ガス終了時あるいは造塊時の溶鋼中に添加することができる。
また、スラブ製造は、コスト低減、さらにはスラブ長手方向における成分あるいは品質の均一性等の経済的・技術的利点のため連続鋳造法の採用が有利ではあるが、従来の造塊スラブの使用を妨げるものではない。
【００２３】
連続鋳造スラブは、スラブ中のインヒビタ−を解離・固溶させるために、1300℃以上の温度に加熱される。その後、このスラブは熱間粗圧延ついで熱間仕上圧延が施されて、通常厚み 1.3〜3.3 mm程度の熱延板とされる。
【００２４】
次に熱延板は、必要に応じ 850〜1100℃程度の温度範囲で熱延板焼鈍（均一化焼鈍ともいう）を施したのち、１回または中間焼鈍を挟む２回以上の冷間圧延を施して最終板厚とするが、高磁束密度で低鉄損の特性を有する製品を得るには最終冷延率（通常55〜90％）に注意を払う必要がある。
このとき、珪素鋼板の渦電流損をできるかぎり小さくする観点から、製品厚の上限は0.5 mmに、またヒステリシス損の弊害を避けるために板厚の下限は0.05mm程度とすることが好ましい。
【００２５】
鋼板表面に対する線状溝の形成は、この最終冷延を終え製品板厚となった鋼板に対して行うのがとりわけ有利であるが、脱炭・１次再結晶焼鈍後に行っても良い。
すなわち、最終冷延板または２次再結晶前後の鋼板の表面に、圧延方向と交差する向きに２〜10mmの間隔で、幅：50〜500 μm 、深さ：0.1 〜50μm の線状の凹領域を形成させるのである。
ここに、線状凹領域の間隔を２〜10mmの範囲に限定したのは、２mmに満たないと鋼板凹凸があまりにも顕著で磁束密度が低下し経済的でなくなり、一方10mmを超えると磁区細分化効果が小さくなるからである。
また、凹領域の幅が50μm に満たないと反磁界効果を利用することが困難となり、一方 500μm を超えると磁束密度が低下し経済的でなくなるので、凹領域の幅は50〜500 μm の範囲に限定した。
さらに、凹領域の深さが 0.1μm に満たないと反磁界効果を効果的に利用することができず、一方50μm を超えると磁束密度が低下し経済的でなくなるので、凹領域の深さは 0.1〜50μm の範囲に限定した。
なお、線状凹領域の形成方向は、圧延方向と直角方向すなわち板幅方向とするのが最適であるが、板幅方向に対し±30°以内であればほぼ同様の効果を得ることができる。
【００２６】
さらに、線状凹領域の形成方法としては、最終冷延板の表面に、印刷によりエッチングレジストを塗布、焼き付けた後、エッチング処理を施し、しかるのち該レジストを除去する方法が、従来のナイフの刃先やレーザー等を用いる方法に比較して、工業的に安定して実施できる点、および引張り張力により一層効果的に鉄損を低減できる点で有利である。
【００２７】
以下、上記のエッチングによる線状溝形成技術の典型例について具体的に説明する。
最終冷延板の表面に、アルキド系樹脂を主成分とするエッチングレジストインキをグラビアオフセット印刷により、非塗布部が圧延方向にほぼ直角に幅：200 μm 、間隔：４mmで線状に残存するように塗布したのち、 200℃で約20秒間焼き付ける。このとき、レジスト厚は２μm 程度とする。このようにしてエッチングレジストを塗布した鋼板に、電解エッチングまたは化学エッチングを施すことにより、幅：200 μm 、深さ：20μm の線状の溝を形成し、ついで有機溶剤中に浸漬してレジストを除去する。この時の電解エッチング条件は、NaCl電解液中で電流密度：10 A/dm²、処理時間：20秒程度、また化学エッチング条件は、HNO₃液中で浸漬時間：10秒間程度とすれば良い。
【００２８】
ついで、鋼板には脱炭焼鈍が施される。この焼鈍は、冷延組織を１次再結晶組織にすると同時に、最終焼鈍（仕上焼鈍とも呼ばれる）で｛１１０｝〈００１〉方位の２次再結晶粒を発達させる場合に有害なＣを除去することを目的とし、例えば 750〜880 ℃の湿水素中で行う。
このような脱炭焼鈍板に対して、上記した線状溝形成処理を施しても良い。
【００２９】
このような脱炭処理を施した後（この後に線状溝形成処理を施した場合には、この線状溝形成処理の後）の鋼板に対して、その表面にTeおよびBiを含む無機化合物を付着させる化学的処理を施す。
この場合に使用するTeの無機化合物としては、TeCl₃, K₂TeO₃, Na₂TeO₃およびH₂TeO₄・2H₂O等が好適である。一方、Biの無機化合物としては、BiCl₃, Bi(OH)₃およびBi(NO₃)₃・5H₂O等が好適に使用できる。また、この場合の溶液または懸濁液は、これらの無機化合物が溶解し易く、かつ鋼板との反応が良くなるように、30〜100 ℃（好ましくは70〜90℃）程度とするのが望ましく、さらにその際の鋼板上への溶液または懸濁液の塗布方法としては、鋼板を浸積、鋼板上に噴霧、あるいは電解等、従来公知の方法がいずれも好適に使用できる。
【００３０】
ここに、上記したTe化合物およびBi化合物の鋼板表面に対する塗布濃度は単位面積：１m²当たり0.01〜5.0 ｇ（テルルおよび／またはビスマス換算）とする必要がある。
というのは、鋼板表面に対する塗布濃度が 0.1 g/m² に満たないと、添加による効果が小さく、一方 5.0 g/m² を超えるとやはり添加効果が強すぎて、２次再結晶粒の発達を阻害するからである。望ましくは、0.05〜0.2 g/m²である。
また、これらの化合物の溶液および懸濁液中における添加濃度は 0.001〜0.1 mol/l とすることが好ましい。というのは、添加濃度が 0.001 mol/lに満たないと添加による効果が小さく、一方 0.1 mol/lを超えると添加効果が強すぎ、かえって２次再結晶粒の発達を阻害するだけでなく、コスト高となるからである。
【００３１】
このような処理を施した後の珪素鋼板の最終焼鈍は、｛１１０｝〈００１〉方位の２次再結晶粒を十分発達させるために施されるもので、通常箱焼鈍によって直ちに1000℃以上に昇温し、その温度に保持することによって行われる。この最終焼鈍は通常、マグネシア等の焼鈍分離剤を塗布して行い、表面にフォルステライトと呼ばれる下地被膜も同時に形成する。
しかしながら、場合によっては、フォルステライト下地被膜を形成させないような焼鈍分離剤の使用も可能である。すなわち、フォルステライト下地被膜を形成させる MgOの含有比率を低減し（50wt％以下）、代わってかかる被膜を形成させない CaO, Al₂O₃, CaSiO₃, SiO₂, PbCl₃等の含有比率を高く（50wt％以上）した焼鈍分離剤を用いるのである。
【００３２】
この発明において｛１１０｝〈００１〉方位に高度に集積した２次再結晶組織を発達させるためには、 820℃から900 ℃の低温での保定焼鈍が有利であるが、その他、例えば 0.5〜15℃/h程度の昇温速度での徐熱焼鈍でも良い。
【００３３】
また、上記したような、鋼板表面に対するTe化合物やBi化合物の直接塗布処理に代えて、これらの化合物を焼鈍分離剤中に含有させることもできる。
この場合にも、鋼板表面に対するTe化合物やBi化合物の塗布濃度は鋼板の単位面積：１m²当たり 0.1〜5.0 ｇ（テルルおよび／またはビスマス換算）とする必要がある。
【００３４】
【実施例】
実施例１
Ｃ：0.077 wt％, Si：3.36wt％, Mn：0.072 wt％, Se：0.020 wt％, Sb：0.025 wt％, Al：0.021 wt％, Ｎ：0.0078wt％およびMo：0.012 wt％を含有し、残部は実質的にFeの組成になる珪素鋼連鋳スラブを、1350℃で4 時間の加熱処理後、熱間圧延を施して厚み：2.2 mmの熱延板とした。ついで1000℃の均一化焼鈍を施した後、1000℃の中間焼鈍を挟む２回の冷間圧延を施して0.23mm厚の最終冷延板とした。
【００３５】
ついで、最終冷延板の表面に、アルキド系樹脂を主成分とするエッチングレジストインキをグラビアオフセット印刷により、非塗布部が圧延方向とほぼ直角な方向に幅：200 μm 、圧延方向の間隔：４mmで線状に残存するように塗布したのち、200 ℃で約20秒間焼付けた。このときのレジスト厚は２μm であった。このようにしてエッチングレジストを塗布した鋼板に、電解エッチングを施すことにより、幅：200 μm 、深さ：20μm の線状の溝を形成し、ついで有機溶剤中に浸漬してレジストを除去した。この時の電解エッチングは、NaCl電解液中で電流密度：10 A/dm²、処理時間：20秒間の条件で行った。
【００３６】
その後、 850℃の湿H₂中で脱炭・１次再結晶焼鈍を行った後、次の２条件の処理を施した。
▲１▼ TeCl₃の希薄水溶液中（0.005 mol/l, 80 ℃) に30秒間浸積（鋼板表面に対するTeの付着量：0.03 g/m²)。
▲２▼ BiCl₃の希薄水溶液中（0.01 mol/l, 80℃) に30秒間浸積（鋼板表面に対する Biの付着量：0.05 g/m²)。
▲３▼ TeCl₃＋BiCl₃ の希薄水溶液中（ TeCl₃：0.003 mol/l, BiCl₃：0.007 mol/l, 65℃) に30秒間浸積（鋼板表面に対するTeの付着量：0.02 g/m² 、同じくBiの付着量：0.03 g/m²)。
【００３７】
その後、鋼板表面に MgO(5wt%), CaO(25wt%), Al₂O₃(50wt%), CaSiO₃(10wt%) およびSiO₂(10wt%) の組成になる焼鈍分離剤をスラリ−塗布し、ついで 850℃で15時間の焼鈍後、 850℃から12℃/hの速度で1150℃まで昇温してゴス方位に強く集積した２次再結晶粒を発達させた後、1200℃の乾H₂中で純化処理を施した。
このときの磁気特性は次のとおりであった。
▲１▼Ｂ₈ : 1.92Ｔ, Ｗ_17/50 ：0.63 W/kg
▲２▼Ｂ₈ : 1.92Ｔ, Ｗ_17/50 ：0.65 W/kg
▲３▼Ｂ₈ : 1.92Ｔ, Ｗ_17/50 ：0.62 W/kg
【００３８】
実施例２
Ｃ：0.043 wt％, Si：3.40wt％, Mn：0.071 wt％, Se：0.020 wt％, Sb：0.025 wt％およびMo：0.012 wt％を含有し、残部は実質的にFeの組成になる珪素鋼連鋳スラブを、1340℃で5 時間加熱処理後、熱間圧延を施して厚み：2.4 mmの熱延板とした。ついで、 900℃の均一化焼鈍後、 950℃の中間焼鈍を挟む２回の冷間圧延を施して0.23mm厚の最終冷延板とした。
【００３９】
その後、最終冷延板の表面に、アルキド系樹脂を主成分とするエッチングレジストインキをグラビアオフセット印刷により、非塗布部が圧延方向とほぼ直角な方向に幅：200 μm 、圧延方向の間隔：４mmで線状に残存するように塗布したのち、200 ℃で約20秒間焼付けた。このときのレジスト厚は２μm であった。このようにしてエッチングレジストを塗布した鋼板に、電解エッチングを施すことにより、幅：200 μm 、深さ：20μm の線状の溝を形成し、ついで有機溶剤中に浸漬してレジストを除去した。この時の電解エッチングは、NaCl電解液中で電流密度：10 A/dm²、処理時間：20秒間の条件で行った。
【００４０】
ついで、820 ℃の湿H₂中で脱炭・１次再結晶焼鈍を施したのち、H₂TeO₃を含む80℃の希薄水溶液中(0.02mol/l) に20秒間浸積処理を施した（鋼板表面におけるTeの付着量：0.08 g/m²)。
その後、珪素鋼板は、鋼板表面にMgO を主成分とする焼鈍分離剤をスラリ−塗布し、ついで 850℃で50時間の保定焼鈍によりゴス方位に強く集積した２次再結晶粒を発達させた後、1200℃の乾H₂中で純化処理を施した。
かくして得られた珪素鋼板の磁気特性は次のとおりであった。
Ｂ₈ ： 1.88 Ｔ
Ｗ_17/50 ： 0.73 W/kg
【００４１】
実施例３
Ｃ：0.044 wt％, Si：3.38wt％, Mn：0.063 wt％, Se：0.019 wt％, Sb：0.023 wt％およびMo：0.012 wt％を含有し、残部は実質的にFeの組成になる珪素鋼熱延板（厚み：2.4 mm）を、 950℃の中間焼鈍を挟む２回の冷間圧延によって0.23mm厚の最終冷延板（厚み：0.23mm）としたのち、実施例２と同様の磁区細分化処理を施してから、820 ℃の湿H₂中で脱炭・１次再結晶焼鈍を施した。
ついで、鋼板の表面に、H₂TeO₃を添加配合した MgO系の焼鈍分離剤を、塗布後の鋼板表面における付着量が 0.02 g/m²となる量塗布してから、850 ℃で50ｈの２次再結晶焼鈍、引き続き乾水素中で1180℃，５ｈの純化焼鈍を施した。
【００４２】
かくして得られた珪素鋼板の磁気特性は次のとおりであった。
Ｂ₈ ： 1.88 Ｔ
Ｗ_17/50 ： 0.72 W/kg
なお、上記したようなTe化合物の添加がない通常の焼鈍分離剤を用いて、同様の最終仕上げ焼鈍を施して得た比較材の磁気特性は次のとおりであった。
Ｂ₈ ： 1.87 Ｔ
Ｗ_17/50 ： 0.85 W/kg
【００４３】
【発明の効果】
かくして、本発明によれば、従来法に従い、化学的処理や磁区細分化処理を単独で施した場合の相和効果よりも一段と優れた鉄損特性を有する超低鉄損一方向性珪素鋼板を、極めて安価にしかも高生産性の下で得ることができる。
【図面の簡単な説明】
【図１】本発明に従い磁区細分化処理後の鋼板表面にTe化合物やBi化合物を溶液または懸濁液として塗布したのち焼鈍分離剤を塗布した場合(a) 、同じくTe化合物やBi化合物を焼鈍分離剤中に混入して塗布した場合(b) および従来法に従い平坦な鋼板表面にこれらの化合物を塗布した場合(c) における、Te，Bi化合物の塗布位置と２次再結晶核の発生位置との位置関係を比較して示した図である。[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a method for producing a low iron loss unidirectional electrical steel sheet, and in particular, effectively uses a magnetic domain subdivision technique by forming a linear concave region on the steel sheet surface and a Goss orientation preferential growth technique by application of tellurium, bismuth, or the like. By combining with the above, it is possible to improve the iron loss characteristics as well as the magnetic flux density.
[0002]
[Prior art]
Unidirectional electrical steel sheets are mainly used as iron cores for transformers and other electrical equipment, and are required to have excellent magnetic properties, that is, high magnetic flux density and low iron loss.
In order to obtain a unidirectional electrical steel sheet with good magnetic properties, it is necessary to be composed of secondary recrystallized grains whose crystal orientations are highly aligned at {110} <001>. In order to completely perform this secondary recrystallization, an appropriate precipitation dispersed phase called an inhibitor such as AlN, MnS, MnSe, etc. exists in the steel sheet before finish annealing, and 1 other than {110} <001>. It is important to effectively suppress the growth of the next crystal grains.
[0003]
The secondary recrystallized grains with {110} <001> orientation are often generated near the surface layer of the steel sheet. Therefore, the steel sheet surface layer is particularly emphasized, and the surface layer part is characterized by chemical treatment at each stage of the manufacturing process. Various methods for improving the magnetic characteristics by improving the above have been proposed.
A typical example is a method in which a special compound is added to the annealing separator applied to the surface of the steel plate prior to final finish annealing. For example, Japanese Patent Publication No. 43-5996 discloses a method before final finish annealing. There has been proposed a method of suppressing the growth of primary grains by adding a sulfur compound in an annealing separator and sulfurating the sulfur content on the surface during annealing.
However, with this method, it has been extremely difficult to uniformly apply the sulfur compound over the entire area of the steel sheet and to exert its effect over the entire surface.
[0004]
In Japanese Patent Publication No. 60-26812, a dilute aqueous solution or suspension containing a tellurium compound is applied to the surface of the steel sheet, and then annealed in the middle of the process to enhance the suppression force in the vicinity of the surface of the steel sheet. A method for producing a unidirectional electrical steel sheet that is uniform and has an excellent magnetic flux density has been proposed.
Furthermore, in Japanese Patent Application Laid-Open Nos. 7-173642 and 7-278676, bismuth is contained in an annealing separator mainly composed of MgO applied to the surface of a silicon steel sheet after decarburization and primary recrystallization annealing. There has been proposed a method of preferentially growing secondary recrystallized grains which are mixed with chlorides and which are strongly accumulated in the {110} <001> orientation in the secondary recrystallization annealing in the next step.
However, each of the above-described methods has not been able to sufficiently meet the recent strict requirements for magnetic characteristics.
[0005]
[Problems to be solved by the invention]
The present invention has been developed in view of the above-described circumstances, and by effectively combining the above-described chemical processing technology and magnetic domain fragmentation technology, not only the magnetic flux density but also the iron loss characteristics are greatly improved. The object is to propose an advantageous method for producing a unidirectional electrical steel sheet.
[0006]
[Means for Solving the Problems]
Now, in order to improve the chemical treatment technique as described above, the inventors tried applying a magnetic domain subdivision technique of a method of forming a linear concave region on the steel sheet surface in the process of repeating various experiments. It was found that an effect far superior to that obtained by simply performing the magnetic domain subdivision treatment was obtained.
Therefore, when investigating this cause, when tellurium compound or the like is applied to the surface of the steel sheet in which the linear concave region is formed, it is natural that the tellurium compound or the like enters the bottom surface of the concave region. Compared to the case where it is applied to a smooth surface that does not have a linear concave region, it should be closer to the surface layer region (region of 1/10 to 1/5 of the plate thickness from the steel plate surface) where nuclei of goth-oriented grains are generated. As a result, the inventors have found that the effects of tellurium compounds and the like on the preferential growth in the Goss direction are significantly improved.
The present invention is based on the above findings.
[0007]
That is, in the present invention, a silicon-containing steel slab is hot-rolled and then subjected to cold rolling twice or more with one or more intermediate annealings, followed by decarburization and primary recrystallization annealing, and then an annealing separator. In producing a unidirectional electrical steel sheet by applying a series of processes for final finishing annealing after coating,
The final cold rolling or after decarburization and primary recrystallization steel sheet surface after annealing, after facilities for domain refining, a linear concave regions forming process by etching,
A solution or suspension containing an inorganic compound containing tellurium and / or bismuth on the steel plate surface after decarburization and primary recrystallization annealing is 0.01 to 5.0 g per unit area: 1 m ² (in terms of tellurium and / or bismuth). it characterized by applying a range of) a production method of an oriented electrical steel sheet (first invention).
[0008]
In addition, the present invention, after hot rolling a silicon-containing steel slab, performs cold rolling at least once with one or two intermediate sandwiches, and then after decarburization and primary recrystallization annealing, an annealing separator is added. In producing a unidirectional electrical steel sheet by applying a series of processes for final finishing annealing after coating,
The final cold rolling or after decarburization and primary recrystallization steel sheet surface after annealing, after facilities for domain refining, a linear concave regions forming process by etching,
An inorganic compound containing tellurium and / or bismuth in the annealing separator applied to the surface of the steel sheet after decarburization and primary recrystallization annealing is attached to the surface of the steel sheet after the annealing separator is applied per unit area: 1 m ² . 0.01-5.0 a g producing method of an oriented electrical steel sheet you wherein be contained within an amount of (tellurium and / or bismuth conversion) (second invention).
[0009]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, experimental data on which the present invention is based will be described.
C: 0.067 wt%, Si: 3.43 wt%, Mn: 0.072 wt%, Al: 0.022 wt%, N: 0.0080 wt%, Sb: 0.025 wt%, Se: 0.020 wt% and Mo: 0.012 wt% The balance is a continuous cast steel slab with a composition of Fe, hot rolled into a 2.2 mm thick hot-rolled sheet, and then homogenized annealing at 1000 ° C for 2 minutes, followed by intermediate annealing at 1050 ° C Cold rolling was performed twice to obtain a final cold-rolled sheet having a thickness of 0.23 mm.
[0010]
Thereafter, the final cold rolled sheet was processed as follows.
(1) On the surface of the final cold-rolled sheet, an etching resist ink mainly composed of alkyd resin is gravure offset printed so that the non-coated part is almost perpendicular to the rolling direction and has a width of 200 μm and a spacing of 4 mm. After coating so that it remained, it was baked at 200 ° C. for 3 minutes. The resist thickness at this time was 2 μm. By applying electrolytic etching to the steel plate coated with the etching resist in this way, a linear groove with a width of 200 μm and a depth of 20 μm was formed and then immersed in an organic solvent to remove the resist. . The electrolytic etching at this time was performed in a NaCl electrolyte under the conditions of current density: 10 A / dm ² and treatment time: 20 seconds.
(2) For comparison, a silicon steel plate not subjected to these treatments was also prepared.
[0011]
Thereafter, these steel plates were decarburized and primary recrystallized annealed in wet H ₂ at 840 ° C., and then subjected to the following treatment on the steel plate surfaces.
(1) (A) K ₂ TeO ₃ , (B) Na ₂ TeO ₃ , (C) H ₂ TeO ₄・ 2H ₂ O, (D) H ₂ TeO _{4 at} a concentration of 0.001 to 0.01 mol / l at 80 ° C・ Immersion treatment was carried out in a 2H ₂ O + Bi (NO ₃ ) ₃ / 5H ₂ O aqueous solution.
(2) (A) BiCl ₃ , (B) BiCl ₃ + TeCl ₃ , (C) Bi (OH) ₃ , (D) Bi (NO ₃ ) ₃ · 5H _{2 at} a concentration of 0.007 to 0.05 mol / l at 80 ° C It was immersed in an aqueous solution O.
( ₃ ) It was immersed in an aqueous solution of (A) N ₂ S ₂ O ₃ .5H ₂ O, (B) K ₂ S, (C) H ₂ SeO _{4 at} a concentration of 0.001 to 0.05 mol / l at 80 ° C.
(4) For comparison, a silicon steel sheet not subjected to such chemical treatment was also prepared.
[0012]
After that, an annealing separator mainly composed of MgO was applied on the surface of these steel plates, and after annealing at 850 ° C for 15 hours, the temperature was increased from 850 ° C to 1080 ° C at a rate of 12 ° C / h. After developing recrystallized grains strongly accumulated in the Goss orientation, purification treatment was performed in dry H ₂ at 1200 ° C.
Table 1 shows the results of examining the magnetic properties of the silicon steel sheet thus obtained.
[0013]
For some samples, the above-mentioned cold-rolled sheets were decarburized and primary recrystallized annealing in 840 ° C wet H ₂ , and then CaO (30 wt%), An annealing separator containing the compounds described in (1), ( ₂ ) and ( ₃ ) above was applied to the basic composition of Al ₂ O ₃ (50 wt%) and SiO ₂ (20 wt%), and then 850 ° C. After annealing for 15 hours, the temperature was increased from 850 ° C to 1080 ° C at a rate of 12 ° C / h to develop recrystallized grains that accumulated strongly in the Goss orientation, and then purified in dry H ₂ at 1200 ° C. Was given.
Table 2 shows the results of examining the magnetic properties of the silicon steel sheet thus obtained.
[0014]
[Table 1]

[0015]
[Table 2]

[0016]
As shown in Table 1 and Table 2, both when the inorganic compound containing tellurium and / or bismuth is directly applied to the surface of the silicon steel sheet and when it is mixed in the annealing separator and applied to the steel sheet surface. It is noted that an iron loss improvement effect that is far superior to the summation effect obtained when the chemical treatment and the magnetic domain subdivision treatment are each performed independently as in the prior art.
[0017]
As described above, the reason why an extremely low iron loss can be obtained by combining the chemical processing technique and the magnetic domain subdivision technique according to the present invention is shown schematically in FIGS. 1 (a), (b), and (c). As shown in comparison, in the conventional state (c), the Bi or Te coating position is far from the position where the secondary recrystallization nuclei with Goth orientation are generated, whereas in the case of the present invention (a), In (b), the application position of Bi or Te is close to the generation position of secondary recrystallization nuclei, so that the inhibitor effect by these elements is more effectively exhibited.
Therefore, as shown in Fig. 1 (b), rather than adding an inorganic compound of Te or Bi to the annealing separator, as shown in Fig. 1 (a), the inorganic compound of Te or Bi is dissolved in an aqueous solution. It is more effective to add a small amount to the surface of the steel sheet and make it adhere directly to the surface of the steel sheet.
[0018]
[Action]
As the silicon steel plate which is the material of the present invention, any of the conventionally known component compositions are suitable, but the representative compositions are as follows.
C: 0.01-0.08wt%
If C is less than 0.01 wt%, the suppression of hot-rolled texture will be insufficient and large elongated grains will be formed, leading to deterioration of magnetic properties. On the other hand, if C is more than 0.08 wt%, decarburization will occur. Since it takes time and is not economical, it is preferable that the content be about 0.01 to 0.08 wt%.
[0019]
Si: 2.0-4.0wt%
If Si is less than 2.0 wt%, sufficient electric resistance cannot be obtained, so eddy current loss increases and iron loss is deteriorated. On the other hand, if it exceeds 4.0 wt%, brittle cracking is likely to occur during cold rolling. Therefore, it is preferable to set it as about 2.0-4.0 wt%.
[0020]
Mn: 0.01-0.2 wt%
Mn is an important component that determines MnS or MnSe as a dispersed precipitation phase that affects secondary recrystallization of a unidirectional silicon steel sheet. When the amount of Mn is less than 0.01 wt%, the absolute amount of MnS or the like necessary for causing secondary recrystallization is insufficient, causing incomplete secondary recrystallization and increasing surface defects called blisters. On the other hand, if it exceeds 0.2 wt%, even if dissociated solid solution of MnS or the like is performed in slab heating, etc., the dispersed precipitation phase that precipitates during hot rolling tends to coarsen, and the optimum size distribution desired as an inhibitor is impaired. Therefore, Mn is preferably about 0.01 to 0.2 wt%.
[0021]
S: 0.008 to 0.1 wt%, Se: 0.003 to 0.1 wt%
Both S and Se are preferably 0.1 wt% or less, in particular, S is in the range of 0.008 to 0.1 wt%, and Se is preferably in the range of 0.003 to 0.1 wt%. This is because if these exceed 0.1 wt%, hot workability and cold workability deteriorate, while if the lower limit values are not reached, the primary grain growth inhibiting function as MnS and MnSe will not produce a special effect. It is.
In addition, the addition of conventionally known Al, Sb, Cu, Sn, B, N and the like as an inhibitor does not hinder the effects of the present invention.
[0022]
Next, the manufacturing process of the ultra-low iron loss unidirectional silicon steel sheet according to the present invention will be described.
First, in order to melt the raw material, an LD converter, an electric furnace, a flat furnace, and other known steel making furnaces can be used, as well as vacuum melting and RH degassing treatment can be used in combination.
According to the present invention, as a method for adding a small amount of S, Se or other primary grain growth inhibitor contained in the raw material to the molten steel, any conventionally known method may be used, such as an LD converter, It can be added to the molten steel at the end of RH degassing or ingot forming.
For slab manufacturing, the continuous casting method is advantageous due to cost reduction and economic / technical advantages such as uniformity of components or quality in the longitudinal direction of the slab, but the use of conventional ingot slabs. It does not prevent it.
[0023]
The continuous cast slab is heated to a temperature of 1300 ° C. or higher in order to dissociate and dissolve the inhibitor in the slab. Thereafter, this slab is subjected to hot rough rolling followed by hot finish rolling to obtain a hot rolled sheet having a thickness of about 1.3 to 3.3 mm.
[0024]
Next, the hot-rolled sheet is subjected to hot-rolled sheet annealing (also referred to as homogenization annealing) in the temperature range of about 850 to 1100 ° C., if necessary, and then cold-rolled at least once with intermediate annealing. However, in order to obtain a product having high magnetic flux density and low iron loss characteristics, it is necessary to pay attention to the final cold rolling rate (usually 55 to 90%).
At this time, from the viewpoint of minimizing the eddy current loss of the silicon steel plate, the upper limit of the product thickness is preferably 0.5 mm, and the lower limit of the plate thickness is preferably about 0.05 mm in order to avoid the adverse effects of hysteresis loss.
[0025]
The formation of the linear groove on the steel sheet surface is particularly advantageous when it is performed on the steel sheet that has finished the final cold rolling and has a product thickness, but may be performed after decarburization and primary recrystallization annealing.
That is, linear concaves with a width of 50 to 500 μm and a depth of 0.1 to 50 μm on the surface of the final cold-rolled sheet or the steel sheet before and after secondary recrystallization at intervals of 2 to 10 mm in a direction intersecting the rolling direction. A region is formed.
Here, the interval between the linear concave areas is limited to the range of 2 to 10 mm. If the distance is less than 2 mm, the unevenness of the steel sheet is too remarkable and the magnetic flux density is lowered and not economical. This is because the conversion effect is reduced.
Also, if the width of the recessed area is less than 50 μm, it is difficult to use the demagnetizing field effect, while if it exceeds 500 μm, the magnetic flux density decreases and it is not economical, so the width of the recessed area is in the range of 50 to 500 μm. Limited to.
Furthermore, if the depth of the recessed area is less than 0.1 μm, the demagnetizing field effect cannot be effectively used.On the other hand, if it exceeds 50 μm, the magnetic flux density is reduced and it is not economical. The range was limited to 0.1 to 50 μm.
The formation direction of the linear concave region is optimally a direction perpendicular to the rolling direction, that is, the sheet width direction, but substantially the same effect can be obtained as long as it is within ± 30 ° with respect to the sheet width direction. .
[0026]
Further, as a method for forming the linear concave region, a method of applying an etching resist to the surface of the final cold-rolled plate by printing and baking it, and then performing an etching process, and then removing the resist, is a conventional knife. Compared to a method using a cutting edge, a laser, or the like, it is advantageous in that it can be carried out industrially stably and in that iron loss can be more effectively reduced by tensile tension.
[0027]
Hereinafter, a typical example of the above-described technique for forming a linear groove by etching will be described in detail.
On the surface of the final cold-rolled sheet, an etching resist ink mainly composed of an alkyd resin is printed by gravure offset printing so that the non-coated part remains linearly at a width of 200 μm and a spacing of 4 mm almost perpendicular to the rolling direction. Bake at 200 ° C for about 20 seconds. At this time, the resist thickness is about 2 μm. By applying electrolytic etching or chemical etching to the steel plate coated with the etching resist in this way, a linear groove having a width of 200 μm and a depth of 20 μm is formed, and then immersed in an organic solvent to form the resist. Remove. Electrolytic etching conditions at this time may be a current density of 10 A / dm ² in a NaCl electrolytic solution, a processing time of about 20 seconds, and chemical etching conditions may be an immersion time of about 10 seconds in an HNO ₃ liquid. .
[0028]
Next, the steel plate is subjected to decarburization annealing. This annealing makes the cold-rolled structure a primary recrystallized structure, and at the same time removes harmful C when developing secondary recrystallized grains with {110} <001> orientation in final annealing (also called finish annealing). For example, in wet hydrogen at 750-880 ° C.
You may perform the above-mentioned linear groove formation process with respect to such a decarburization annealing board.
[0029]
An inorganic compound containing Te and Bi on the surface of the steel plate after such decarburization treatment (after this linear groove formation treatment if a linear groove formation treatment is performed thereafter) Apply chemical treatment to attach
TeCl ₃ , K ₂ TeO ₃ , Na ₂ TeO _3, H ₂ TeO ₄ .2H ₂ O, and the like are preferable as the Te inorganic compound used in this case. On the other hand, BiCl ₃ , Bi (OH) _3, Bi (NO ₃ ) ₃ .5H ₂ O and the like can be suitably used as the inorganic compound of Bi. The solution or suspension in this case is desirably about 30 to 100 ° C. (preferably 70 to 90 ° C.) so that these inorganic compounds are easily dissolved and the reaction with the steel plate is improved. Further, as a method for applying the solution or suspension onto the steel plate at that time, any conventionally known method such as immersion of the steel plate, spraying on the steel plate, or electrolysis can be suitably used.
[0030]
Here, the coating concentration of the above Te compound and Bi compound on the steel sheet surface needs to be 0.01 to 5.0 g (converted to tellurium and / or bismuth) per unit area: 1 m ² .
This is because when the coating concentration on the steel sheet surface is less than 0.1 g / m ² , the effect of addition is small, while when it exceeds 5.0 g / m ² , the effect of addition is too strong and the secondary recrystallized grains develop. It is because it inhibits. Desirably, it is 0.05 to 0.2 g / m ² .
The concentration of these compounds in the solution and suspension is preferably 0.001 to 0.1 mol / l. This is because if the additive concentration is less than 0.001 mol / l, the effect of addition is small, while if it exceeds 0.1 mol / l, the effect of addition is too strong, not only inhibiting the development of secondary recrystallized grains, This is because the cost becomes high.
[0031]
The final annealing of the silicon steel sheet after such treatment is performed in order to sufficiently develop the secondary recrystallized grains with the {110} <001> orientation. This is done by raising the temperature and holding at that temperature. This final annealing is usually performed by applying an annealing separator such as magnesia, and a base film called forsterite is simultaneously formed on the surface.
However, in some cases, it is possible to use an annealing separator that does not form a forsterite undercoat. That is, the content ratio of MgO that forms the forsterite undercoat is reduced (50 wt% or less), and the content ratio of CaO, Al ₂ O ₃ , CaSiO ₃ , SiO ₂ , PbCl ₃ etc. that does not form such a film is increased instead. An annealing separator (50 wt% or more) is used.
[0032]
In this invention, in order to develop a secondary recrystallized structure that is highly accumulated in the {110} <001> orientation, it is advantageous to perform retention annealing at a low temperature of 820 ° C to 900 ° C. Slow thermal annealing at a rate of temperature rise of about ° C / h may be used.
[0033]
Moreover, it replaces with the direct application | coating process of Te compound and Bi compound with respect to the steel plate surface as mentioned above, and these compounds can also be contained in an annealing separation agent.
Also in this case, the coating concentration of the Te compound or Bi compound on the steel plate surface needs to be 0.1 to 5.0 g (in terms of tellurium and / or bismuth) per unit area of the steel plate: 1 m ² .
[0034]
【Example】
Example 1
C: 0.077 wt%, Si: 3.36 wt%, Mn: 0.072 wt%, Se: 0.020 wt%, Sb: 0.025 wt%, Al: 0.021 wt%, N: 0.0078 wt% and Mo: 0.012 wt% The remainder of the silicon steel continuous slab having a substantially Fe composition was heat-treated at 1350 ° C. for 4 hours, and then hot-rolled to obtain a hot-rolled sheet having a thickness of 2.2 mm. Next, uniform annealing at 1000 ° C. was performed, and then cold rolling was performed twice with the intermediate annealing at 1000 ° C. to obtain a final cold-rolled sheet having a thickness of 0.23 mm.
[0035]
Next, on the surface of the final cold-rolled sheet, an etching resist ink mainly composed of an alkyd resin is subjected to gravure offset printing so that the width of the non-coated part is approximately 200 μm in the direction substantially perpendicular to the rolling direction, and the interval in the rolling direction is 4 mm. After coating so as to remain linearly, it was baked at 200 ° C. for about 20 seconds. The resist thickness at this time was 2 μm. The steel plate coated with the etching resist was subjected to electrolytic etching to form a linear groove having a width of 200 μm and a depth of 20 μm, and then immersed in an organic solvent to remove the resist. The electrolytic etching at this time was performed in a NaCl electrolyte under the conditions of current density: 10 A / dm ² and treatment time: 20 seconds.
[0036]
Thereafter, decarburization and primary recrystallization annealing were performed in 850 ° C. wet H ₂ , and then the following two conditions were applied.
(1) Submerged in a dilute aqueous solution of TeCl ₃ (0.005 mol / l, 80 ° C.) for 30 seconds (the amount of Te attached to the steel plate surface: 0.03 g / m ² ).
(2) Submerged in a dilute aqueous solution of BiCl ₃ (0.01 mol / l, 80 ° C.) for 30 seconds (the amount of Bi attached to the steel sheet surface: 0.05 g / m ² ).
( ₃ ) Submerged in a dilute aqueous solution of TeCl ₃ + BiCl ₃ (TeCl ₃ : 0.003 mol / l, BiCl ₃ : 0.007 mol / l, 65 ° C) for 30 seconds (Amount of Te attached to the steel plate surface: 0.02 g / m ² Also, the amount of Bi deposited: 0.03 g / m ² ).
[0037]
Then, MgO (5wt%) on the surface of the steel sheet, CaO (25wt%), Al 2 O 3 (50wt%), CaSiO 3 (10wt%) and SiO ₂ slurry annealing separating agent consisting of the composition of (10 wt%) - coated Then, after annealing at 850 ° C. for 15 hours, the temperature was increased from 850 ° C. to 1150 ° C. at a rate of 12 ° C./h to develop secondary recrystallized grains that accumulated strongly in the Goss orientation, and then dried at 1200 ° C. It was subjected to purification treatment in H _2.
The magnetic properties at this time were as follows.
(1) B ₈ : 1.92T, W _17/50 : 0.63 W / kg
(2) B ₈ : 1.92T, W _17/50 : 0.65 W / kg
(3) B ₈ : 1.92T, W _17/50 : 0.62 W / kg
[0038]
Example 2
Silicon containing C: 0.043 wt%, Si: 3.40 wt%, Mn: 0.071 wt%, Se: 0.020 wt%, Sb: 0.025 wt% and Mo: 0.012 wt%, with the balance being substantially Fe composition The steel continuous cast slab was heat-treated at 1340 ° C. for 5 hours and then hot-rolled to obtain a hot-rolled sheet having a thickness of 2.4 mm. Then, after uniform annealing at 900 ° C., cold rolling was performed twice with an intermediate annealing at 950 ° C. to obtain a final cold-rolled sheet having a thickness of 0.23 mm.
[0039]
Then, on the surface of the final cold-rolled sheet, an etching resist ink mainly composed of an alkyd resin is subjected to gravure offset printing so that the width of the non-coated part is approximately 200 μm in the direction substantially perpendicular to the rolling direction and the spacing in the rolling direction is 4 mm. After coating so as to remain linearly, it was baked at 200 ° C. for about 20 seconds. The resist thickness at this time was 2 μm. The steel plate coated with the etching resist was subjected to electrolytic etching to form a linear groove having a width of 200 μm and a depth of 20 μm, and then immersed in an organic solvent to remove the resist. The electrolytic etching at this time was performed in a NaCl electrolyte under the conditions of current density: 10 A / dm ² and treatment time: 20 seconds.
[0040]
Next, after decarburization and primary recrystallization annealing in wet H ₂ at 820 ° C, it was immersed in a dilute aqueous solution (0.02 mol / l) at 80 ° C containing H ₂ TeO ₃ for 20 seconds. (Te adhesion amount on steel plate surface: 0.08 g / m ² ).
After that, after the silicon steel sheet was developed with secondary recrystallized grains that were strongly accumulated in the Goss orientation by slurry-coating an annealing separator mainly composed of MgO on the surface of the steel sheet, and then by holding annealing at 850 ° C. for 50 hours. Then, purification treatment was performed in dry H ₂ at 1200 ° C.
The magnetic properties of the silicon steel sheet thus obtained were as follows.
B ₈ : 1.88 T
W _17/50 : 0.73 W / kg
[0041]
Example 3
Silicon containing C: 0.044 wt%, Si: 3.38 wt%, Mn: 0.063 wt%, Se: 0.019 wt%, Sb: 0.023 wt% and Mo: 0.012 wt%, with the balance being substantially Fe composition The hot-rolled steel sheet (thickness: 2.4 mm) was made into a final cold-rolled sheet (thickness: 0.23 mm) having a thickness of 0.23 mm by cold rolling twice with intermediate annealing at 950 ° C., and the same as in Example 2 After magnetic domain refinement treatment, decarburization and primary recrystallization annealing were performed in 820 ° C. wet H ₂ .
Next, an MgO-based annealing separator containing H ₂ TeO ₃ added to the surface of the steel sheet was applied in an amount such that the adhesion amount on the steel sheet surface after application was 0.02 g / m ^2, and then 50 hours at 850 ° C. Secondary recrystallization annealing was performed, followed by purification annealing at 1180 ° C. for 5 hours in dry hydrogen.
[0042]
The magnetic properties of the silicon steel sheet thus obtained were as follows.
B ₈ : 1.88 T
W _17/50 : 0.72 W / kg
In addition, the magnetic properties of the comparative material obtained by subjecting the same final finish annealing to the conventional annealing separator without addition of the Te compound as described above were as follows.
B ₈ : 1.87 T
W _17/50 : 0.85 W / kg
[0043]
【The invention's effect】
Thus, according to the present invention, according to the conventional method, an ultra-low iron loss unidirectional silicon steel sheet having iron loss characteristics far superior to the summing effect when chemical treatment or magnetic domain subdivision treatment is performed alone. It is extremely inexpensive and can be obtained with high productivity.
[Brief description of the drawings]
FIG. 1 shows a case where a Te compound or Bi compound is applied as a solution or suspension on a steel plate surface after magnetic domain refinement according to the present invention, and then an annealing separator is applied (a). Application position of Te and Bi compounds and occurrence of secondary recrystallization nuclei in the case of coating in the separating agent (b) and in the case of applying these compounds to the flat steel plate surface according to the conventional method (c) FIG.

Claims (2)

After hot-rolling the silicon-containing steel slab, it is subjected to cold rolling at least once with intermediate or intermediate annealing, followed by decarburization and primary recrystallization annealing, and after applying an annealing separator, In producing a unidirectional electrical steel sheet by a series of processes for finishing annealing,
The final cold rolling or after decarburization and primary recrystallization steel sheet surface after annealing, after facilities for domain refining, a linear concave regions forming process by etching,
A solution or suspension containing an inorganic compound containing tellurium and / or bismuth on the steel plate surface after decarburization and primary recrystallization annealing is 0.01 to 5.0 g per unit area: 1 m ² (in terms of tellurium and / or bismuth). manufacturing method of an oriented electrical steel sheet you characterized by applying a range of). After hot-rolling the silicon-containing steel slab, it is subjected to cold rolling at least once with intermediate or intermediate annealing, followed by decarburization and primary recrystallization annealing, and after applying an annealing separator, In producing a unidirectional electrical steel sheet by a series of processes for finishing annealing,
The final cold rolling or after decarburization and primary recrystallization steel sheet surface after annealing, after facilities for domain refining, a linear concave regions forming process by etching,
An inorganic compound containing tellurium and / or bismuth in the annealing separator applied to the surface of the steel sheet after decarburization and primary recrystallization annealing is attached to the surface of the steel sheet after the annealing separator is applied per unit area: 1 m ² . 0.01 to 5.0 g manufacturing method of an oriented electrical steel sheet you wherein be contained within an amount of (tellurium and / or bismuth conversion).

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