JP6687919B2 - Grain-oriented electrical steel sheet and method for manufacturing the same - Google Patents
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Description
本発明は、方向性電磁鋼板とその製造方法に関し、具体的には優れた磁気特性と被膜特性を有する方向性電磁鋼板とその製造方法に関するものである。 The present invention relates to a grain-oriented electrical steel sheet and a method for producing the same, and specifically to a grain-oriented electrical steel sheet having excellent magnetic properties and coating properties and a method for producing the same.
電磁鋼板は、変圧器やモータの鉄心等として広く用いられている軟磁性材料であり、中でも方向性電磁鋼板は、結晶方位がＧｏｓｓ方位と呼ばれる｛１１０｝＜００１＞方位に高度に集積し、磁気特性に優れていることから、主として大型の変圧器の鉄心等に使用されている。 Magnetic steel sheets are soft magnetic materials that are widely used as iron cores for transformers and motors. Among them, grain-oriented magnetic steel sheets are highly integrated in the {110} <001> orientation whose crystal orientation is called the Goss orientation. Due to its excellent magnetic properties, it is mainly used for iron cores of large transformers.
変圧器における無負荷損（エネルギーロス）を低減するためには、低鉄損であることが必要である。方向性電磁鋼板の鉄損を低減する方法としては、Ｓｉ含有量の増加や、板厚の低減、結晶方位の配向性向上、鋼板への張力付与、鋼板表面の平滑化、二次再結晶組織の細粒化などが有効であることが知られている。 In order to reduce the no-load loss (energy loss) in the transformer, it is necessary to have a low iron loss. As a method of reducing the iron loss of the grain-oriented electrical steel sheet, the Si content is increased, the sheet thickness is reduced, the orientation of the crystal orientation is improved, the tension is applied to the steel sheet, the surface of the steel sheet is smoothed, and the secondary recrystallized structure is obtained. It is known that fine graining and the like are effective.
上記方法において、二次再結晶をコントロールして結晶方位の配向性を向上させたり、二次再結晶組織の細粒化を図ったりするためには、インヒビタ成分の種類や量、冷延圧下率、一次再結晶焼鈍パターン、二次再結晶焼鈍前の鋼板表面状態など様々な要素を最適化する必要がある。 In the above method, in order to improve the orientation of the crystal orientation by controlling the secondary recrystallization, or to aim at the grain refinement of the secondary recrystallization structure, the type and amount of the inhibitor component, cold rolling reduction It is necessary to optimize various factors such as the primary recrystallization annealing pattern and the steel sheet surface state before the secondary recrystallization annealing.
ところで、上記二次再結晶焼鈍前の鋼板表面状態を改善して、良好な磁気特性を得る方法としては、例えば、特許文献１には、冷間圧延で最終板厚に仕上げた鋼板表面に、Ｃｕ，Ｓｎ，ＣｏおよびＮｉのうちから選ばれる１種または２種以上の金属または合金を０．１〜８５ｍｇ／ｍ２電着させ、しかる後に脱炭焼鈍を行うことで、コイルの全長および全幅にわたって欠陥のない均一で密着性に優れた被膜を有し、かつ、磁気特性にも優れた方向性けい素鋼板を製造する方法が開示されている。
By the way, as a method for improving the surface state of the steel sheet before the secondary recrystallization annealing to obtain good magnetic properties, for example, in
また、特許文献２には、インヒビタ成分を含有しない鋼スラブを素材として、一次再結晶焼鈍後、鋼板表面にＳｉ，Ｃｕ，Ｓｎ，Ｃｏ，Ｎｉのうちから選ばれる１種または２種以上の金属含有物を該金属換算の合計量で０．１〜５０ｍｇ／ｍ２の範囲で電着し、しかる後、焼鈍分離剤を塗布することによって、優れた磁気特性、被膜特性を得る方向性電磁鋼板の製造方法が開示されている。
Further, in
また、特許文献３には、最終冷間圧延後の鋼板表面の算術平均粗さを０．４０μｍ以下に調整し、その後の脱炭焼鈍に先立って、電解脱脂法で鋼板表面にＳｉを含有する電着物を０．１ｍｇ／ｍ２以上付着させる洗浄処理を施し、次いで、雰囲気を調整した脱炭焼鈍を施すことにより、工業的生産においても安定して高磁束密度の方向性電磁鋼板を製造する方法が開示されている。
Further, in
しかしながら、発明者らの検証結果によれば、上記特許文献１に開示の方法は、磁気特性や被膜特性が改善される効果にバラツキが大きく、安定した効果は得られない。また、特許文献２に開示の方法は、主に被膜特性を改善する技術であり、磁気特性については、やはりバラツキが大きく、場合によっては劣化することもある。さらに、特許文献３に開示の方法は、脱炭焼鈍前にＳｉ電着物を形成させているが、Ｓｉの電着物自体が脱炭焼鈍時のバリアとなってＳｉＯ２の内部酸化を不均一にすることが頻発した。すなわち、わずかな電解浴の経時変化や、電解前の洗浄の不均一などがあると、Ｓｉ電着物が板面に均一に付着しないため、脱炭焼鈍で形成されるサブスケールの保護性がコイル内で不均一となり、磁気特性のバラツキが大きくなったり、被膜特性のムラが増大したりする。
However, according to the verification results of the inventors, the method disclosed in
また、方向性電磁鋼板をトランスの鉄心として巻きコアやＥＩコアなどに利用する場合、加工時に導入される歪みを除去するため、８００℃程度の温度で歪取焼鈍を施すことが行われているが、この際、大気やＤＸガスなど、被膜や地鉄との反応性が高い雰囲気で焼鈍することが多い。このような雰囲気で焼鈍を行うと、被膜や被膜が損傷して被膜密着性が劣化することがある。特にスリットした鋼板の端面では、被膜が剥離しやすいため、トランス使用時に、鋼板が導通し、場合によってはコアが溶損するという大きなトラブルに発展することもある。 When a grain-oriented electrical steel sheet is used as an iron core of a transformer in a wound core, an EI core, or the like, strain relief annealing is performed at a temperature of about 800 ° C. to remove strain introduced during processing. However, at this time, it is often annealed in an atmosphere having high reactivity with the coating or the base iron, such as air or DX gas. When annealing is performed in such an atmosphere, the coating or the coating may be damaged and the coating adhesion may deteriorate. In particular, at the end surface of the slit steel plate, the coating film is easily peeled off, so that when the transformer is used, the steel plate becomes conductive, and in some cases, the core may be melted and damaged, which may cause a big trouble.
本発明は、従来技術が抱える上記問題点に鑑みてなされたものであり、その目的は、磁気特性に優れるだけでなく、ＤＸガスのような反応性の高い雰囲気で歪取焼鈍を行う場合でも被膜特性に優れる方向性電磁鋼板を提供するとともに、その有利な製造方法を提案することにある。 The present invention has been made in view of the above problems of the conventional technique, and an object thereof is not only excellent in magnetic characteristics but also when performing strain relief annealing in a highly reactive atmosphere such as DX gas. An object of the present invention is to provide a grain-oriented electrical steel sheet having excellent coating properties and to propose an advantageous manufacturing method thereof.
発明者らは、上記課題の解決に向けて鋭意検討を重ねた。その結果、脱炭焼鈍前に鋼板表面に電着する金属の種類ではなく、電着粒子の析出形態が重要であり、これを適性化することによって、脱炭焼鈍の際に形成される内部酸化層が改善され、ひいては磁気特性や被膜特性が改善されることを見出し、本発明を開発するに至った。 The inventors have conducted extensive studies to solve the above problems. As a result, not the type of metal electrodeposited on the steel sheet surface before decarburization annealing, but the precipitation morphology of the electrodeposited particles is important.By optimizing this, the internal oxidation formed during decarburization annealing The inventors have found that the layers are improved, and thus the magnetic properties and coating properties are improved, leading to the development of the present invention.
すなわち、本発明は、Ｃ：０．００５ｍａｓｓ％以下、Ｓｉ：２．５〜４．５ｍａｓｓ％およびＭｎ：０．０３〜０．３０ｍａｓｓ％を含有し、残部がＦｅおよび不可避的不純物からなる成分組成を有し、フォルステライト質下地被膜を有する方向性電磁鋼板であって、上記下地被膜表面をＥＰＭＡでマッピング分析したときのＯ強度の標準偏差が平均値の０．１５以下であることを特徴とする方向性電磁鋼板である。 That is, the present invention contains C: 0.005 mass% or less, Si: 2.5 to 4.5 mass% and Mn: 0.03 to 0.30 mass%, with the balance being Fe and inevitable impurities. And a forsterite undercoat, the grain-oriented electrical steel sheet having a standard deviation of O intensity of 0.15 or less of an average value when the undercoat surface is subjected to mapping analysis by EPMA. It is a grain-oriented electrical steel sheet.
本発明の上記鋼板は、上記成分組成に加えてさらに、Ｎｉ：０．０１〜０．４ｍａｓｓ％、Ｃｒ：０．０１〜０．２５ｍａｓｓ％、Ｃｕ：０．０１〜０．３０ｍａｓｓ％、Ｐ：０．００５〜０．１０ｍａｓｓ％、Ｓｂ：０．００５〜０．１０ｍａｓｓ％、Ｓｎ：０．００５〜０．１０ｍａｓｓ％、Ｂｉ：０．００５〜０．１０ｍａｓｓ％、Ｍｏ：０．００５〜０．１０ｍａｓｓ％、Ｂ：０．０００２〜０．００２５ｍａｓｓ％、Ｔｅ：０．０００５〜０．０１ｍａｓｓ％、Ｎｂ：０．００１〜０．０１ｍａｓｓ％、Ｖ：０．００１〜０．０１ｍａｓｓ％およびＴａ：０．００１〜０．０１ｍａｓｓ％のうちから選ばれる１種または２種以上を含有することを特徴とする。 The steel sheet of the present invention is, in addition to the above-mentioned composition, further Ni: 0.01 to 0.4 mass%, Cr: 0.01 to 0.25 mass%, Cu: 0.01 to 0.30 mass%, P: 0.005 to 0.10 mass%, Sb: 0.005 to 0.10 mass%, Sn: 0.005 to 0.10 mass%, Bi: 0.005 to 0.10 mass%, Mo: 0.005 to 0. 10 mass%, B: 0.0002 to 0.0025 mass%, Te: 0.0005 to 0.01 mass%, Nb: 0.001 to 0.01 mass%, V: 0.001 to 0.01 mass% and Ta: 0. It is characterized by containing one or more selected from 0.001 to 0.01 mass%.
また、本発明は、Ｃ：０．０３〜０．０８ｍａｓｓ％、Ｓｉ：２．５〜４．５ｍａｓｓ％およびＭｎ：０．０３〜０．３０ｍａｓｓ％を含有し、残部がＦｅおよび不可避的不純物からなる鋼素材を熱間圧延して熱延板とし、熱延板焼鈍を施した後あるいは熱延板焼鈍を施すことなく、１回または中間焼鈍を挟む２回以上の冷間圧延して最終板厚の冷延板とし、一次再結晶焼鈍を兼ねた脱炭焼鈍を施した後、鋼板表面に焼鈍分離剤を塗布し、仕上焼鈍する一連の工程からなる方向性電磁鋼板の製造方法において、上記最終板厚とする冷間圧延から脱炭焼鈍までの間において、鋼板表面に平均粒径が７０ｎｍ以下の金属粒子を２５個／μｍ２以上電着析出させることを特徴とする請求項１に記載の方向性電磁鋼板の製造方法を提案する。 Further, the present invention contains C: 0.03 to 0.08 mass%, Si: 2.5 to 4.5 mass% and Mn: 0.03 to 0.30 mass%, and the balance is Fe and inevitable impurities. Steel sheet is hot-rolled into a hot-rolled sheet, and after cold-rolled sheet annealing or without hot-rolled sheet annealing, cold rolling is performed once or two or more times with intermediate annealing sandwiched between them to obtain the final sheet. As a thick cold-rolled sheet, subjected to decarburization annealing that also serves as primary recrystallization annealing, an annealing separator is applied to the steel sheet surface, and a method for producing a grain-oriented electrical steel sheet comprising a series of steps of finish annealing in the above, The metal sheet having an average particle size of 70 nm or less is electrodeposited at 25 particles / μm 2 or more on the surface of the steel plate during cold rolling from the final plate thickness to decarburization annealing. We propose a method for manufacturing grain-oriented electrical steel sheet.
本発明の製造方法に用いる上記鋼素材は、上記成分組成に加えてさらに、Ｓｅ：０．０１〜０．０２５ｍａｓｓ％および／またはＳ：０．０１〜０．０２５ｍａｓｓ％を含有することを特徴とする。 The steel material used in the production method of the present invention is characterized by further containing Se: 0.01 to 0.025 mass% and / or S: 0.01 to 0.025 mass% in addition to the above component composition. To do.
また、本発明の製造方法に用いる上記鋼素材は、上記成分組成に加えてさらに、Ａｌ：０．０１〜０．０３ｍａｓｓ％およびＮ：０．００３〜０．０１ｍａｓｓ％を含有し、あるいは、Ａｌ：０．０１〜０．０３ｍａｓｓ％、Ｎ：０．００３〜０．０１ｍａｓｓ％、Ｓｅ：０．０１〜０．０２５ｍａｓｓ％および／またはＳ：０．０１〜０．０２５ｍａｓｓ％を含有することを特徴とする。 Further, the above steel material used in the production method of the present invention further contains Al: 0.01 to 0.03 mass% and N: 0.003 to 0.01 mass% in addition to the above component composition, or Al : 0.01 to 0.03 mass%, N: 0.003 to 0.01 mass%, Se: 0.01 to 0.025 mass% and / or S: 0.01 to 0.025 mass% And
また、本発明の製造方法に用いる上記鋼素材に含まれる不可避的不純物中のＡｌ，Ｎ，ＳおよびＳｅは、それぞれＡｌ：０．０１ｍａｓｓ％未満、Ｎ：０．００５０ｍａｓｓ％未満、Ｓ：０．００５０ｍａｓｓ％未満およびＳｅ：０．００３０ｍａｓｓ％未満であること特徴とする。 Further, Al, N, S and Se in the unavoidable impurities contained in the steel material used in the production method of the present invention are Al: less than 0.01 mass%, N: less than 0.0050 mass%, S: 0. It is characterized in that it is less than 0050 mass% and Se: less than 0.0030 mass%.
また、本発明の製造方法に用いる上記鋼素材は、上記成分組成に加えてさらに、Ｎｉ：０．０１〜０．４ｍａｓｓ％、Ｃｒ：０．０１〜０．２５ｍａｓｓ％、Ｃｕ：０．０１〜０．３０ｍａｓｓ％、Ｐ：０．００５〜０．１０ｍａｓｓ％、Ｓｂ：０．００５〜０．１０ｍａｓｓ％、Ｓｎ：０．００５〜０．１０ｍａｓｓ％、Ｂｉ：０．００５〜０．１０ｍａｓｓ％、Ｍｏ：０．００５〜０．１０ｍａｓｓ％、Ｂ：０．０００２〜０．００２５ｍａｓｓ％、Ｔｅ：０．０００５〜０．０１ｍａｓｓ％、Ｎｂ：０．００１〜０．０１ｍａｓｓ％、Ｖ：０．００１〜０．０１ｍａｓｓ％およびＴａ：０．００１〜０．０１ｍａｓｓ％のうちから選ばれる１種または２種以上を含有することを特徴とする。 Further, the steel material used in the production method of the present invention is, in addition to the above-mentioned composition, further Ni: 0.01 to 0.4 mass%, Cr: 0.01 to 0.25 mass%, Cu: 0.01 to. 0.30 mass%, P: 0.005-0.10 mass%, Sb: 0.005-0.10 mass%, Sn: 0.005-0.10 mass%, Bi: 0.005-0.10 mass%, Mo : 0.005 to 0.10 mass%, B: 0.0002 to 0.0025 mass%, Te: 0.0005 to 0.01 mass%, Nb: 0.001 to 0.01 mass%, V: 0.001 to 0 0.01 mass% and Ta: 0.001 to 0.01 mass%, and one or more kinds selected from the above are contained.
本発明によれば、磁気特性と被膜特性が共に優れる方向性電磁鋼板を安定して提供することができる。 According to the present invention, it is possible to stably provide a grain-oriented electrical steel sheet having excellent magnetic properties and coating properties.
発明者らは、脱炭焼鈍前の鋼板表面に金属粒子を電着させる処理を行ったとき、磁気特性が大きく改善されたり、全く改善されなかったりして、バラツキが大きい原因について調査するため、以下の実験を行った。
Ｃ：０．０６５ｍａｓｓ％、Ｓｉ：３．４４ｍａｓｓ％、Ｍｎ：０．０８ｍａｓｓ％、Ａｌ：０．０３ｍａｓｓ％およびＮ：０．００８ｍａｓｓ％を含有する鋼を溶製し、連続鋳造法で鋼スラブとした後、１４１０℃に再加熱し、熱間圧延して板厚２．４ｍｍの熱延板とし、１０５０℃×６０ｓの熱延板焼鈍を施した後、一次冷間圧延して中間板厚１．８ｍｍとし、１１２０℃×８０ｓの中間焼鈍を施した後、２００℃の温度で二次冷間圧延して、最終板厚０．２３ｍｍの冷延板とした。
The inventors, when performing a process of electrodepositing metal particles on the surface of the steel sheet before decarburization annealing, magnetic properties are greatly improved, or not improved at all, in order to investigate the cause of the large variation, The following experiment was conducted.
Steel containing C: 0.065 mass%, Si: 3.44 mass%, Mn: 0.08 mass%, Al: 0.03 mass% and N: 0.008 mass% was melted and formed into a steel slab by a continuous casting method. After that, it is reheated to 1410 ° C., hot-rolled into a hot-rolled sheet having a thickness of 2.4 mm, subjected to hot-rolled sheet annealing at 1050 ° C. × 60 s, and then primary cold-rolled to obtain an
次いで、上記冷延板をアルカリ液で脱脂した後、塩酸酸洗し、さらに電解脱脂を行った。この際、上記塩酸酸洗の条件を、下記４水準に振り分けた。
水準１）塩酸酸洗なし
水準２）液温が５０℃の３ｍａｓｓ％塩酸水溶液に１０ｓ間浸漬
水準３）液温が６０℃の５ｍａｓｓ％塩酸水溶液に１０ｓ間浸漬
水準４）液温が７０℃の１０ｍａｓｓ％塩酸水溶液に１０ｓ間浸漬
Next, the cold-rolled sheet was degreased with an alkaline solution, washed with hydrochloric acid, and further electrolytically degreased. At this time, the conditions of the hydrochloric acid pickling were divided into the following four levels.
Level 1) No hydrochloric acid pickling Level 2) Immersion in 3 mass% hydrochloric acid aqueous solution at 50 ° C for 10 s Level 3) Immersion in 5 mass% hydrochloric acid aqueous solution at 60 ° C for 10 s Level 4) Liquid temperature at 70 ° C Immersion in 10 mass% hydrochloric acid aqueous solution for 10 s
また、上記電解脱脂の電解浴には、３ｍａｓｓ％ＮａＯＨ＋０．５ｍａｓｓ％界面活性剤＋１．５ｍａｓｓ％グルコン酸銅（Ｃ１２Ｈ２２Ｏ１４Ｃｕ）よりなる水溶液を用いた。この浴中で鋼板を陰極として電解処理し、Ｃｕを金属換算で、片面当たり５０ｍｇ／ｍ２電着させた。なお、Ｃｕの電着量は、蛍光Ｘ線で分析した、予め作成しておいた検量線に基づき定量した。また、比較として、グルコン酸銅を添加しない電解浴でも電解脱脂も行った。 Further, an aqueous solution containing 3 mass% NaOH + 0.5 mass% surfactant + 1.5 mass% copper gluconate (C 12 H 22 O 14 Cu) was used for the electrolytic degreasing electrolytic bath. In this bath, a steel plate was used as a cathode for electrolytic treatment, and Cu was metal-deposited at 50 mg / m 2 per one surface. The Cu electrodeposition amount was quantified based on a calibration curve prepared in advance, which was analyzed by fluorescent X-ray. For comparison, electrolytic degreasing was also performed in an electrolytic bath containing no copper gluconate.
次いで、５０ｖｏｌ％Ｈ２−５０ｖｏｌ％Ｎ２、露点６２℃の湿潤雰囲気下で、８４０℃の温度に１００ｓ間保持する、一次再結晶焼鈍を兼ねた脱炭焼鈍を施した。
その後、鋼板表面に、ＭｇＯを主剤とし添加剤として酸化チタンをＴｉ換算で５ｍａｓｓ％添加した焼鈍分離剤を塗布し、乾燥した後、二次再結晶焼鈍と水素雰囲気下で１２００℃×７ｈｒの純化処理とからなる仕上焼鈍を施した。
その後、未反応の焼鈍分離剤を除去し、絶縁被膜を塗布し、該被膜の焼付けと形状矯正を兼ねた平坦化焼鈍を８００℃×３０ｓで行い、製品板とした。
Then, decarburization annealing that doubled as primary recrystallization annealing was performed by maintaining the temperature at 840 ° C. for 100 s in a humid atmosphere with 50 vol% H 2 -50 vol% N 2 and a dew point of 62 ° C.
After that, an annealing separator containing MgO as a main component and titanium oxide as an additive in an amount of 5 mass% in terms of Ti was applied to the surface of the steel sheet and dried, followed by secondary recrystallization annealing and purification at 1200 ° C. for 7 hours in a hydrogen atmosphere. And a finish annealing consisting of treatment.
After that, the unreacted annealing separator was removed, an insulating coating was applied, and flattening annealing that served as both baking and shape correction of the coating was performed at 800 ° C. for 30 seconds to obtain a product plate.
斯くして得た製品板について、磁気特性と被膜密着性を調査した。
ここで、磁気特性は、ＪＩＳ Ｃ２５５０に規定された方法で、磁束密度Ｂ８および鉄損Ｗ１７／５０を測定した。
また、被膜の密着性は、８５０℃×３ｈｒのＤＸガス雰囲気（ＣＯ：１ｖｏｌ％＋Ｈ２：１ｖｏｌ％＋ＣＯ２：１２ｖｏｌ％＋残部：Ｎ２、露点１０℃）で歪取焼鈍を施した後、径の異なる丸棒に鋼板を巻き付けたときに被膜が剥離しなかった最小の径（曲げ剥離径）を測定した。
The magnetic properties and coating adhesion of the product plate thus obtained were investigated.
Here, magnetic characteristics were measured by magnetic flux density B 8 and iron loss W 17/50 by the method specified in JIS C2550.
The adhesion of the coating, DX gas atmosphere 850 ℃ × 3hr (CO: 1vol % + H 2: 1vol% + CO 2: 12vol% + balance: N 2,
上記測定の結果を図１に示した。この図から、グルコン酸銅を添加しない、即ち、Ｃｕ電着をさせない条件では、電着前の酸洗条件によらず、磁気特性、被膜密着性はほぼ一定の値を示しているのに対して、Ｃｕ電着をさせた条件では、適度に酸洗した、水準２）および３）では、顕著に磁気特性と被膜特性が改善されている。しかし、過度に酸洗した水準３）では、磁気特性、被膜特性は電着させない条件と同レベルにまで低下した。また、酸洗しない水準１）では、磁気特性、被膜特性とも、Ｃｕを電着させない場合より大きく劣化している。 The result of the above measurement is shown in FIG. From this figure, under the condition that copper gluconate is not added, that is, the condition that Cu electrodeposition is not performed, the magnetic properties and the coating adhesion show almost constant values regardless of the pickling condition before electrodeposition. Under the conditions of Cu electrodeposition, the magnetic properties and the film properties are remarkably improved in the levels 2) and 3), which are appropriately pickled. However, in the excessively pickled level 3), the magnetic properties and the coating properties were reduced to the same level as in the condition without electrodeposition. Further, in the level 1) where pickling is not performed, both the magnetic characteristics and the coating characteristics are significantly deteriorated as compared with the case where Cu is not electrodeposited.
この原因を調査するために、仕上焼鈍後の鋼板表面（下地被膜付き）表面をＥＰＭＡで分析した。分析した領域は５０μｍ×５０μｍで、この領域について０．２μｍピッチで酸素（Ｏ）分析を行い、マッピング表示した。一例として、酸洗しない水準１）の結果と、５ｍａｓｓ％塩酸で酸洗した水準３）の結果を図２に示した。この図から、酸洗しない水準１）では、酸素の分布が不均一となっているのに対して、５ｍａｓｓ％塩酸で酸洗した水準３）では酸素の分布が均一であり、下地被膜が均一に形成されていることがわかる。 In order to investigate the cause, the surface of the steel sheet surface (with the undercoat) after finish annealing was analyzed by EPMA. The analyzed region was 50 μm × 50 μm, and oxygen (O) analysis was performed on this region at a pitch of 0.2 μm, and mapping was displayed. As an example, the results of Level 1) without pickling and the results of Level 3) with pickling with 5 mass% hydrochloric acid are shown in FIG. From this figure, the oxygen distribution is non-uniform in the non-pickled level 1), while the oxygen distribution is uniform in the 5 mass% hydrochloric acid-pickled level 3) and the undercoat is uniform. It can be seen that it is formed in.
次いで、上記マッピングデータのＯ強度について、全測定値の平均値と標準偏差を求め、各水準ごとの平均値に対する標準偏差の比率を求めた結果を図３に示した。この図から、３〜５ｍａｓｓ％塩酸で酸洗してＣｕを電着させた水準２，３で最も低い値を示し、下地被膜の均一性が増していることがわかる。また、この傾向は、磁気特性や被膜密着性の傾向ともよく一致していることがわかる。
Next, with respect to the O intensity of the above mapping data, the average value and standard deviation of all measured values were obtained, and the ratio of the standard deviation to the average value for each level was obtained. The results are shown in FIG. From this figure, it can be seen that the
また、酸洗しない水準１）と、５ｍａｓｓ％塩酸で酸洗した水準３）のＣｕ電着後のＳＥＭ像を図４に示した。塩酸で酸洗していない水準１）では、大きさの異なる不均一なＣｕ粒子が析出しているのに対して、５ｍａｓｓ％塩酸で酸洗した水準３）では、微細なＣｕ粒子が均一に析出している。さらに、電着したＣｕ粒子の平均粒径と析出密度を、ＳＥＭ像を画像解析して求め、その結果を図５に示した。この図から、磁気特性や被膜密着性が良好であった水準２）や水準３では、電着したＣｕ粒子の平均粒径が７０ｎｍ以下で、電着したＣｕ粒子の析出密度が２５個／μｍ２以上であり、中でも、最も良好な特性を示した水準３）では、Ｃｕ粒子が最も微細かつ均一に析出していることがわかる。
Further, FIG. 4 shows SEM images after Cu electrodeposition of level 1) without pickling and level 3) with pickling with 5 mass% hydrochloric acid. In level 1) which is not pickled with hydrochloric acid, non-uniform Cu particles of different sizes are precipitated, whereas in level 3) which is pickled with 5 mass% hydrochloric acid, fine Cu particles are uniform. It has been deposited. Further, the average particle size and the deposition density of the electrodeposited Cu particles were obtained by image analysis of the SEM image, and the results are shown in FIG. From this figure, in Level 2) and
上記のように、同じ目付量でＣｕを電着させても、Ｃｕの析出形態に大きな変化が生じる原因について、発明者らは以下のように考える。
仕上焼鈍時の雰囲気が磁気特性に大きく影響することは従来から知られている。これは、仕上焼鈍中に雰囲気中に含まれる水分や窒素分が鋼中に侵入して、インヒビタを分解したり粗大化したりして、粒成長抑制力を低下させるためであるとされている。この対策としては、脱炭焼鈍で形成される内部酸化膜を均一かつ緻密にすることが有効であると考えられている。そのため、従来技術の多くは、内部酸化膜の断面構造に着目して、均一で緻密な構造の内部酸化膜を得る方法について検討してきた。
As described above, the inventors consider the cause of a large change in the precipitation form of Cu even when Cu is electrodeposited with the same basis weight as follows.
It is conventionally known that the atmosphere during finish annealing has a great influence on the magnetic properties. It is believed that this is because the water and nitrogen contained in the atmosphere during the finish annealing penetrate into the steel to decompose the inhibitors and coarsen them, thereby lowering the grain growth suppressing force. As a countermeasure against this, it is considered effective to make the internal oxide film formed by decarburization annealing uniform and dense. Therefore, most of the conventional techniques have focused on the cross-sectional structure of the internal oxide film and examined methods for obtaining the internal oxide film having a uniform and dense structure.
しかし、本発明の上記実験の結果では、鋼板表面内での内部酸化膜のバラツキが大きく、これが製品板の磁気特性、被膜特性に強く影響していることが明らかになった。すなわち、断面における内部酸化膜が均一で緻密であったとしても、鋼板表面内の一部に粗雑で雰囲気の遮蔽性が弱い部分があれば、そこから雰囲気ガスの成分が侵入して、磁気特性や被膜特性に悪影響を及ぼすことになる。これを防ぐには、鋼板表面内での内部酸化膜の均一性を高めなければならない。そのために重要なのが、金属電着した金属粒子の析出状態である。金属粒子が析出した状態で脱炭焼鈍を行うと、析出粒子を核にして内部酸化が進行する。従って、金属粒子を均一に析出させることによって、内部酸化も均一に起こさせることができる。 However, the results of the above-described experiments of the present invention have revealed that the variation of the internal oxide film on the surface of the steel sheet is large and this has a strong influence on the magnetic properties and coating properties of the product sheet. That is, even if the internal oxide film in the cross section is uniform and dense, if a part of the steel sheet surface that is rough and has a weak atmosphere shielding property, the components of the atmosphere gas enter from there and the magnetic characteristics And the film properties will be adversely affected. To prevent this, the uniformity of the internal oxide film on the surface of the steel sheet must be increased. What is important for this is the state of deposition of metal particles that have been electrodeposited by metal. When decarburization annealing is performed in the state where metal particles are deposited, internal oxidation proceeds with the deposited particles as nuclei. Therefore, by precipitating the metal particles uniformly, internal oxidation can also be uniformly caused.
さらに、金属粒子を均一に析出させるためには、電解処理前の鋼板表面を均一にしておくことが必要であり、そのためには、事前の酸洗等で表面状態を均一化しておくことが重要となる。ただし、上記実験結果では、酸洗し過ぎると金属粒子は均一に析出しなかった。この原因は不明であるが、過度の酸洗によって鋼板表面にピットや肌荒れが発生し、そこが起点となって粗大な金属粒子の析出が起こったためと考えられる。 Furthermore, in order to deposit metal particles uniformly, it is necessary to make the surface of the steel sheet uniform before electrolytic treatment, and for that purpose it is important to make the surface state uniform by prior pickling, etc. Becomes However, in the above experimental results, the metal particles were not uniformly deposited after the pickling. The cause of this is not clear, but it is considered that pits and surface roughness were generated on the surface of the steel sheet due to excessive pickling, and this was the starting point for the precipitation of coarse metal particles.
なお、鋼板表面を酸洗等で均一な状態にすれば、金属を析出させなくても均一酸化が進行するとも考えられるが、上記の実験では、このような結果は得られなかった。これは、表面状態を均一化したつもりであっても、結晶方位の違いにより、脱炭焼鈍中の酸化のされ方は異なってしまう、つまり、結晶方位により表面エネルギーが異なるため、酸化のために吸着する酸素分子や水分子の量が異なるためであると考えられる。そして、この違いを緩和するのが、電解で析出した金属粒子であると考えられる。 It should be noted that if the surface of the steel sheet is made uniform by pickling or the like, it is considered that uniform oxidation proceeds even without depositing metal, but in the above experiment, such a result was not obtained. This is because even if the surface state is intended to be uniform, the way of oxidation during decarburization annealing differs depending on the difference in crystal orientation, that is, the surface energy differs depending on the crystal orientation. It is considered that this is because the amounts of adsorbed oxygen molecules and water molecules are different. Then, it is considered that the metal particles that are electrolytically deposited alleviate this difference.
上記のように、酸洗と金属粒子の電着処理を行い、鋼板の断面方向のみならず表面方向にも均一な内部酸化膜を得ることによって、仕上焼鈍後のフォルステライト被膜（下地被膜）の均一化が促進される。上記均一化の程度は、ＥＰＭＡでマッピング分析することにより得られる下地被膜表面のＯ強度の平均値に対する標準偏差の比で評価することができる。そして、この比が小さい、すなわち、均一な下地被膜を形成させることによって、優れた磁気特性と被膜特性が達成されるのである。 As described above, by performing pickling and electrodeposition of metal particles to obtain a uniform internal oxide film not only in the cross-sectional direction of the steel sheet but also in the surface direction, the forsterite coating (undercoat) after finish annealing Uniformity is promoted. The degree of the above homogenization can be evaluated by the ratio of the standard deviation to the average value of the O intensity of the surface of the undercoat obtained by mapping analysis with EPMA. By forming a uniform undercoat film having a small ratio, that is, excellent magnetic properties and film properties are achieved.
次に、本発明の方向性電磁鋼板の製造に用いる鋼素材（スラブ）の成分組成について説明する。
Ｃ：０．０３〜０．０８ｍａｓｓ％
Ｃは、０．０３ｍａｓｓ％に満たないと、粒界強化効果が失われ、スラブに割れが生じるなど、製造に支障を来たす欠陥を生ずるようになる。一方、０．０８ｍａｓｓ％を超えると、脱炭焼鈍で、磁気時効の起こらない０．００５ｍａｓｓ％以下に低減することが難しくなる。よって、Ｃは０．０３〜０．０８ｍａｓｓ％の範囲とする。好ましくは０．０３５〜０．０７５ｍａｓｓ％の範囲である。
Next, the component composition of the steel material (slab) used for manufacturing the grain-oriented electrical steel sheet of the present invention will be described.
C: 0.03 to 0.08 mass%
If C is less than 0.03 mass%, the grain boundary strengthening effect is lost and cracks occur in the slab, resulting in defects that hinder manufacturing. On the other hand, if it exceeds 0.08 mass%, it becomes difficult to reduce the magnetic aging to 0.005 mass% or less, which does not cause magnetic aging, by decarburization annealing. Therefore, C is in the range of 0.03 to 0.08 mass%. It is preferably in the range of 0.035 to 0.075 mass%.
Ｓｉ：２．５〜４．５ｍａｓｓ％
Ｓｉは、鋼の比抵抗を高め、鉄損を低減するのに必要な元素である。この効果は、２．５ｍａｓｓ％未満では十分ではなく、一方、４．５ｍａｓｓ％を超えると、加工性が低下し、圧延して製造すること困難となる。よって、Ｓｉは２．５〜４．５ｍａｓｓ％の範囲とする。好ましくは２．８〜４．０ｍａｓｓ％の範囲である。
Si: 2.5 to 4.5 mass%
Si is an element necessary for increasing the specific resistance of steel and reducing iron loss. This effect is not sufficient if it is less than 2.5 mass%, while if it exceeds 4.5 mass%, the workability is lowered and it becomes difficult to manufacture by rolling. Therefore, Si is in the range of 2.5 to 4.5 mass%. It is preferably in the range of 2.8 to 4.0 mass%.
Ｍｎ：０．０３〜０．３ｍａｓｓ％
Ｍｎは、鋼の熱間加工性を改善するために必要な元素である。上記効果は、０．０３ｍａｓｓ％未満では十分ではなく、一方、０．３ｍａｓｓ％を超えると、製品板の磁束密度が低下するようになる。よって、Ｍｎは０．０３〜０．３ｍａｓｓ％の範囲とする。好ましくは０．０４〜０．２ｍａｓｓ％の範囲である。
Mn: 0.03 to 0.3 mass%
Mn is an element necessary for improving the hot workability of steel. If the effect is less than 0.03 mass%, the effect is not sufficient. On the other hand, if it exceeds 0.3 mass%, the magnetic flux density of the product plate decreases. Therefore, Mn is set to the range of 0.03 to 0.3 mass%. It is preferably in the range of 0.04 to 0.2 mass%.
上記Ｃ，ＳｉおよびＭｎ以外の成分については、二次再結晶を生じさせるために、インヒビタを利用する場合と、しない場合とで異なる。
まず、二次再結晶を生じさせるために、インヒビタを利用する場合で、例えば、ＡｌＮ系インヒビタを利用するときには、ＡｌおよびＮを、それぞれＡｌ：０．０１〜０．０３ｍａｓｓ％、Ｎ：０．００３〜０．０１ｍａｓｓ％の範囲で含有させるのが好ましい。また、ＭｎＳ・ＭｎＳｅ系インヒビタを利用するときには、前述した量のＭｎの他に、Ｓ：０．０１〜０．０２５ｍａｓｓ％およびＳｅ：０．０１〜０．０２５ｍａｓｓ％のうちの１種または２種を含有させることが好ましい。それぞれ添加量が、上記下限値より少ないと、インヒビタ効果が十分に得られず、一方、上限値を超えると、インヒビタ成分がスラブ加熱時に未固溶で残存し、磁気特性の低下をもたらす。なお、上記ＡｌＮ系とＭｎＳ・ＭｎＳｅ系のインヒビタは併用してもよい。
Regarding the components other than C, Si and Mn, the case where the inhibitor is used to cause the secondary recrystallization and the case where the inhibitor is not used are different.
First, in the case of using an inhibitor to cause secondary recrystallization, for example, when using an AlN-based inhibitor, Al and N are Al: 0.01 to 0.03 mass% and N: 0. It is preferably contained in the range of 003 to 0.01 mass%. When using a MnS / MnSe-based inhibitor, in addition to the amount of Mn described above, one or two of S: 0.01 to 0.025 mass% and Se: 0.01 to 0.025 mass%. Is preferably contained. If the added amount is less than the above lower limit, the inhibitory effect cannot be sufficiently obtained, while if it exceeds the upper limit, the inhibitor component remains undissolved during heating of the slab, resulting in deterioration of magnetic properties. The AlN-based and MnS / MnSe-based inhibitors may be used in combination.
一方、二次再結晶を生じさせるためにインヒビタを利用しない場合には、上述したインヒビタ形成成分であるＡｌ，Ｎ，ＳおよびＳｅの含有量を極力低減し、Ａｌ：０．０１ｍａｓｓ％未満、Ｎ：０．００５０ｍａｓｓ％未満、Ｓ：０．００５０ｍａｓｓ％未満およびＳｅ：０．００３０ｍａｓｓ％未満に低減した鋼素材を用いるのが好ましい。 On the other hand, when the inhibitor is not used to cause the secondary recrystallization, the contents of Al, N, S and Se which are the above-mentioned inhibitor forming components are reduced as much as possible, and Al: less than 0.01 mass%, N It is preferable to use a steel material reduced to less than: 0.0050 mass%, S: less than 0.0050 mass%, and Se: less than 0.0030 mass%.
本発明の方向性電磁鋼板に用いる鋼素材は、上記成分以外に、磁気特性の改善を目的として、Ｎｉ：０．０１〜０．４ｍａｓｓ％、Ｃｒ：０．０１〜０．２５ｍａｓｓ％、Ｃｕ：０．０１〜０．３０ｍａｓｓ％、Ｐ：０．００５〜０．１０ｍａｓｓ％、Ｓｂ：０．００５〜０．１０ｍａｓｓ％、Ｓｎ：０．００５〜０．１０ｍａｓｓ％、Ｂｉ：０．００５〜０．１０ｍａｓｓ％、Ｍｏ：０．００５〜０．１０ｍａｓｓ％、Ｂ：０．０００２〜０．００２５ｍａｓｓ％、Ｔｅ：０．０００５〜０．０１ｍａｓｓ％、Ｎｂ：０．００１〜０．０１ｍａｓｓ％、Ｖ：０．００１〜０．０１ｍａｓｓ％およびＴａ：０．００１〜０．０１ｍａｓｓ％のうちから選ばれる１種または２種以上を適宜含有してもよい。 In addition to the above components, the steel material used for the grain-oriented electrical steel sheet of the present invention is Ni: 0.01 to 0.4 mass%, Cr: 0.01 to 0.25 mass%, Cu: for the purpose of improving magnetic properties. 0.01-0.30 mass%, P: 0.005-0.10 mass%, Sb: 0.005-0.10 mass%, Sn: 0.005-0.10 mass%, Bi: 0.005-0. 10 mass%, Mo: 0.005-0.10 mass%, B: 0.0002-0.0025 mass%, Te: 0.0005-0.01 mass%, Nb: 0.001-0.01 mass%, V: 0 One or two or more selected from 0.001 to 0.01 mass% and Ta: 0.001 to 0.01 mass% may be appropriately contained.
次に、本発明の方向性電磁鋼板の製造方法について説明する。
本発明の方向性電磁鋼板の製造に用いる鋼素材（スラブ）は、上述した成分組成を有する鋼を常法の精錬プロセスで溶製した後、従来公知の造塊−分塊圧延法または連続鋳造法で製造してもよいし、あるいは、直接鋳造法で１００ｍｍ以下の厚さの薄鋳片としてもよい。
Next, a method for manufacturing the grain-oriented electrical steel sheet of the present invention will be described.
The steel material (slab) used in the production of the grain-oriented electrical steel sheet of the present invention is produced by melting steel having the above-described component composition by a conventional refining process, and then forming a conventionally known ingot-segmentation rolling method or continuous casting. It may be manufactured by the method, or a thin cast piece having a thickness of 100 mm or less may be formed by the direct casting method.
上記スラブは常法に従い、例えばインヒビタ成分を含有する場合には１４００℃程度の温度に再加熱した後、一方、インヒビタ成分を含まない場合は１３００℃以下の温度に再加熱した後、熱間圧延に供する。なお、インヒビタ成分を含有しない場合には、連続鋳造後、再加熱することなく直ちに熱間圧延してもよい。また、薄鋳片の場合には、熱間圧延してもよいし、熱間圧延を省略してそのまま以後の工程に進めてもよい。 The above-mentioned slab is reheated to a temperature of about 1400 ° C. when it contains an inhibitor component, while it is reheated to a temperature of 1300 ° C. or less when it does not contain an inhibitor component, followed by hot rolling. To serve. If the inhibitor component is not contained, hot rolling may be performed immediately after continuous casting without reheating. Further, in the case of a thin cast piece, hot rolling may be performed, or hot rolling may be omitted and the process may be directly performed.
次いで、熱間圧延して得た熱延板は、必要に応じて熱延板焼鈍を施す。この熱延板焼鈍の均熱温度は、良好な磁気特性を得るためには、８００〜１１５０℃の範囲とするのが好ましい。８００℃未満では、熱間圧延で形成されたバンド組織が残留し、整粒の一次再結晶組織を得ることが難しくなり、二次再結晶の発達が阻害される。一方、１１５０℃を超えると、熱延板焼鈍後の粒径が粗大化し過ぎて、やはり整粒の一次再結晶組織を得ることが難しくなるからである。 Then, the hot rolled sheet obtained by hot rolling is subjected to hot rolled sheet annealing as necessary. The soaking temperature of this hot-rolled sheet annealing is preferably in the range of 800 to 1150 ° C. in order to obtain good magnetic properties. If the temperature is lower than 800 ° C., the band structure formed by hot rolling remains, and it becomes difficult to obtain a primary recrystallized structure of grain size control, which hinders the development of secondary recrystallization. On the other hand, if the temperature exceeds 1150 ° C., the grain size after the hot-rolled sheet annealing becomes too coarse, and it becomes difficult to obtain a primary recrystallized structure of grain size regulation.
熱延後あるいは熱延板焼鈍後の熱延板は、１回の冷間圧延または中間焼鈍を挟む２回以上の冷間圧延をして最終板厚の冷延板とする。上記中間焼鈍の均熱温度は、９００〜１２００℃の範囲とするのが好ましい。９００℃未満では中間焼鈍後の再結晶粒が細かくなり過ぎたり、一次再結晶組織におけるＧｏｓｓ核が減少して製品板の磁気特定が低下したりするおそれがある。一方、１２００℃を超えると、熱延板焼鈍のときと同様、結晶粒が粗大化し過ぎて整粒の一次再結晶組織を得ることが難しくなる。 The hot-rolled sheet after hot-rolling or after hot-rolled sheet annealing is cold-rolled once or cold-rolled twice or more with intermediate annealing interposed therebetween to obtain a cold-rolled sheet having a final thickness. The soaking temperature of the intermediate annealing is preferably in the range of 900 to 1200 ° C. If the temperature is lower than 900 ° C., the recrystallized grains after the intermediate annealing may become too fine, or the Goss nuclei in the primary recrystallized structure may decrease to lower the magnetic properties of the product sheet. On the other hand, if the temperature exceeds 1200 ° C., the crystal grains become too coarse, and it becomes difficult to obtain a primary recrystallized structure of grain size, as in the case of hot-rolled sheet annealing.
また、最終板厚とする冷間圧延（最終冷間圧延）は、圧延時の鋼板温度を１００〜３００℃の温度に上昇させて圧延する温間圧延としたり、圧延の途中で１００〜３００℃の温度で時効処理を１回または複数回施したりすることが、一次再結晶集合組織を改善し、磁気特性を向上させるのに有効である。 Further, the cold rolling to obtain the final plate thickness (final cold rolling) is a warm rolling in which the steel plate temperature during rolling is raised to a temperature of 100 to 300 ° C, or 100 to 300 ° C during rolling. It is effective to improve the primary recrystallization texture and improve the magnetic properties by performing the aging treatment once or a plurality of times at the temperature.
次いで、最終板厚とした冷延板は、脱炭焼鈍前までの段階で、鋼板表面に金属粒子を電着させる。電着させる金属元素としては特に限定しないが、Ｓｉ，Ｃｕ，Ｓｎ，Ｃｏ，Ｎｉ，Ｔｉ，Ｍｎ，Ｔａ，Ｚｎ，Ｃｒ等が好適である。
このとき、電析させる金属粒子の平均粒径を７０ｎｍ以下とし、析出密度を２５個／μｍ２以上とすることが必要である。平均粒径が大き過ぎたり、析出密度が低過ぎたりすると、脱炭焼鈍時の内部酸化を十分に均一化することができない。好ましくは、金属粒子の平均粒径は５０ｎｍ以下、析出密度は４５個／μｍ２以上である。
Next, the cold-rolled sheet having the final plate thickness has metal particles electrodeposited on the surface of the steel sheet before the decarburization annealing. The metal element to be electrodeposited is not particularly limited, but Si, Cu, Sn, Co, Ni, Ti, Mn, Ta, Zn, Cr and the like are preferable.
At this time, it is necessary to set the average particle size of the metal particles to be electrodeposited to 70 nm or less and the deposition density to 25 particles / μm 2 or more. If the average particle size is too large or the precipitation density is too low, internal oxidation during decarburization annealing cannot be made sufficiently uniform. Preferably, the average particle size of the metal particles is 50 nm or less, and the precipitation density is 45 particles / μm 2 or more.
また、上記金属粒子の電着量は、片面あたりで０．１〜７０ｍｇ／ｍ２の範囲とするのが好ましい。なお、複数の金属を電着させてもよいが、その場合でも０．１〜７０ｍｇ／ｍ２の範囲とするのが好ましい。０．１ｍｇ／ｍ２未満では、電着効果が十分ではなく、一方、７０ｍｇ／ｍ２よりも多いと、電着させた金属によって脱炭焼鈍中に鋼板表面に酸素が拡散するのが過度に妨げられ、酸素目付量不足となり、却って被膜特性が劣化するからである。より好ましい範囲は０．１〜５０ｍｇ／ｍ２の範囲である。 Further, the electrodeposition amount of the metal particles is preferably in the range of 0.1 to 70 mg / m 2 per one surface. It should be noted that a plurality of metals may be electrodeposited, but even in that case, the range of 0.1 to 70 mg / m 2 is preferable. If it is less than 0.1 mg / m 2 , the electrodeposition effect is not sufficient, while if it is more than 70 mg / m 2 , oxygen is excessively diffused on the surface of the steel sheet during decarburization annealing by the electrodeposited metal. This is because it is hindered, the oxygen basis weight becomes insufficient, and rather the coating properties deteriorate. A more preferable range is 0.1 to 50 mg / m 2 .
なお、本発明では、鋼板表面への金属の付着を電着によって行うものとする。これは、電着物の密着性を確保するためと、電着量の制御が容易であるからである。電着方法としては、通常の電気めっきによる方法が好適である。めっき浴は、地鉄の溶解を防ぐために、水酸化ナトリウムや珪酸ナトリウムなどを溶解させたアルカリ浴に、所望の金属イオンを含む化合物を溶解させることで調整する。アルカリ浴に溶解させる化合物としては、エチレンジアミン四酢酸ＥＤＴＡやグルコン酸などの金属キレート塩を用いるのが好適である。このような液で電解すると、金属電着と電解脱脂を兼ねて行うことができる。さらに、この際、鋼板に付着した油分を離脱、乳化させるための界面活性剤を添加してもよい。 In the present invention, the metal is attached to the surface of the steel sheet by electrodeposition. This is because it is easy to control the amount of electrodeposition and to ensure the adhesion of the electrodeposit. As the electrodeposition method, a method using ordinary electroplating is suitable. The plating bath is prepared by dissolving a compound containing a desired metal ion in an alkaline bath in which sodium hydroxide, sodium silicate or the like is dissolved in order to prevent dissolution of base iron. As a compound to be dissolved in an alkaline bath, it is preferable to use a metal chelate salt of ethylenediaminetetraacetic acid EDTA or gluconic acid. By electrolyzing with such a liquid, it is possible to perform both metal electrodeposition and electrolytic degreasing. Further, at this time, a surfactant for removing and emulsifying the oil content adhering to the steel plate may be added.
なお、電解条件としては、所定量の金属を付着させるために、電流密度や電解時間を適宜調節する必要があるが、本発明程度の金属電着量であれば、電流密度０．１〜１００Ａ／ｄｍ２、電解時間０．１〜１０ｓ程度となる。電解処理は、定電流電解、交番電流電解のいずれでも可能である。ただし、交番電流電解では、鋼板がマイナス極となるときの電解時間の合計が上記範囲に収まるようにするのが好ましい。また、金属粒子を、本発明が規定する析出密度となるよう均一微細に析出させるためには、例えば、電解前の鋼板を酸洗や研削などして清浄度を高めたり、電解浴のアルカリ濃度を高くし、金属化合物濃度を低くしたりすることなどが有効である。 In addition, as electrolysis conditions, it is necessary to appropriately adjust the current density and the electrolysis time in order to deposit a predetermined amount of metal, but if the metal electrodeposition amount is about the present invention, the current density is 0.1 to 100 A / Dm 2 , and the electrolysis time is about 0.1 to 10 s. The electrolytic treatment can be either constant current electrolysis or alternating current electrolysis. However, in the alternating current electrolysis, it is preferable that the total electrolysis time when the steel plate becomes a negative electrode falls within the above range. Further, in order to deposit the metal particles uniformly and finely so that the deposition density is regulated by the present invention, for example, the steel sheet before electrolysis is cleaned by pickling or grinding to enhance cleanliness, or the alkali concentration of the electrolytic bath. It is effective to increase the concentration and decrease the concentration of the metal compound.
上記の金属粒子を電着させた鋼板は、その後、一次再結晶焼鈍を兼ねた脱炭焼鈍を施す。脱炭処理の均熱温度は７００〜９００℃、均熱時間は３０〜３００ｓの範囲とするのが好ましい。均熱温度が７００℃未満、均熱時間が３０ｓ未満では、脱炭が不十分となったり、一次再結晶粒が小さくなり過ぎたりして、磁気特性が劣化するおそれがある。一方、均熱温度が９００℃を超えたり、脱炭時間が３００ｓを超えたりすると、一次再結晶粒が大きくなり過ぎ、やはり磁気特性が劣化する。 The steel sheet on which the above-mentioned metal particles are electrodeposited is then subjected to decarburization annealing which also serves as primary recrystallization annealing. The soaking temperature of the decarburizing treatment is preferably 700 to 900 ° C., and the soaking time is preferably 30 to 300 s. If the soaking temperature is less than 700 ° C. and the soaking time is less than 30 s, decarburization may be insufficient or the primary recrystallized grains may be too small, resulting in deterioration of magnetic properties. On the other hand, if the soaking temperature exceeds 900 ° C. or the decarburization time exceeds 300 s, the primary recrystallized grains become too large, and the magnetic properties also deteriorate.
なお、この脱炭焼鈍では、鋼板表層内部にサブスケール（内部酸化層）を形成させるが、前工程で均一微細に電着した金属粒子が、脱炭焼鈍時に形成される内部酸化層を厚さ方向、表面方向に均一化する。また、電着した金属粒子は、脱炭焼鈍中に自らが鋼中に拡散して侵入したり、鋼板表面で酸化されたりする。この酸化物は、後の仕上焼鈍における追加酸化を抑制して、磁気特性を改善する効果がある。 In this decarburization annealing, a subscale (internal oxide layer) is formed inside the surface of the steel sheet, but the metal particles that have been uniformly and finely electrodeposited in the previous step have a thickness of the internal oxide layer formed during decarburization annealing. Direction and surface direction. In addition, the electrodeposited metal particles diffuse themselves into the steel during decarburization annealing, or enter the steel sheet, or are oxidized on the surface of the steel sheet. This oxide has the effect of suppressing additional oxidation in the subsequent finish annealing and improving the magnetic properties.
脱炭焼鈍の雰囲気は、水蒸気−水素分圧ＰＨ２Ｏ／ＰＨ２（酸素ポテンシャル）で０．３〜０．６の範囲とするのが好ましい。これにより、鋼板表層のＳｉＯ２形成量および電着金属の酸化量を適正化することができる。 Atmosphere decarburization annealing, water vapor - a hydrogen partial pressure P H2O / P H2 (oxygen potential) preferably in the range of 0.3 to 0.6. This makes it possible to optimize the amount of SiO 2 formed on the surface layer of the steel sheet and the amount of oxidation of the electrodeposited metal.
なお、上記脱炭焼鈍時の雰囲気は、必ずしも一定とする必要はなく、例えば、前半と後半の２段階に分けて、後半を低露点にして還元処理を施したり、あるいは、加熱時の雰囲気と均熱時の雰囲気を別々にしたりしてもよい。また、加熱時の昇温速度を急速加熱としたり、脱炭焼鈍後に窒化処理を施したりしてもよい。 The atmosphere during the decarburization annealing does not necessarily have to be constant, and for example, it is divided into two stages of the first half and the second half, and the reduction treatment is performed with the second half having a low dew point, or the atmosphere during heating is changed. The atmosphere during soaking may be different. Further, the heating rate at the time of heating may be rapid heating, or nitriding treatment may be performed after decarburization annealing.
上記脱炭焼鈍後は、鋼板表面に焼鈍分離剤を塗布する。この焼鈍分離剤は、主剤として少なくとも５０ｍａｓｓ％のＭｇＯを含み、これに、ＴｉやＣａ，Ｓｒ，Ｍｎ，Ｍｏ，Ｆｅ，Ｃｕ，Ｚｎ，Ｎｉ，Ｓｎ，Ａｌ，Ｋ，ＬｉＫなどの酸化物、硫酸塩、塩化物、ホウ酸塩、珪酸塩、硝酸塩、チタン酸塩、水酸化物などを１種または２種以上添加したものを用いるのが好ましい。 After the decarburization annealing, an annealing separator is applied to the surface of the steel sheet. This annealing separator contains MgO of at least 50 mass% as a main component, and contains Ti, Ca, Sr, Mn, Mo, Fe, Cu, Zn, Ni, Sn, Al, K, LiK, and other oxides and sulfuric acid. It is preferable to use one or two or more of salts, chlorides, borates, silicates, nitrates, titanates and hydroxides added.
上記焼鈍分離剤を塗布した鋼板は、その後、コイル状に巻き取った状態で、二次再結晶焼鈍と、それに続いて純化処理する仕上焼鈍を施す。これにより、Ｇｏｓｓ方位に高度に集積した二次再結晶組織を発達させるとともに、フォルステライト被膜を形成させることができる。上記仕上焼鈍は、二次再結晶を発現させるためには８００℃以上に、また、二次再結晶を十分に完了させるためには１１００℃程度まで加熱するのが好ましい。また、引き続き行う純化処理では、フォルステライト被膜を形成させるためには１２００℃程度の温度まで加熱するのが好ましい。なお、インヒビタ形成成分を含まない素材を用いる場合は、純化処理は省略してもよい。 The steel sheet coated with the annealing separating agent is then subjected to secondary recrystallization annealing in the state of being wound into a coil, followed by finishing annealing for purification treatment. This makes it possible to develop a secondary recrystallized structure highly integrated in the Goss direction and form a forsterite coating. The finish annealing is preferably performed at a temperature of 800 ° C. or higher in order to cause secondary recrystallization, and to approximately 1100 ° C. in order to sufficiently complete the secondary recrystallization. Further, in the subsequent purification treatment, it is preferable to heat to a temperature of about 1200 ° C. in order to form a forsterite film. If a material containing no inhibitor forming component is used, the purification treatment may be omitted.
このようにして製造した方向性電磁鋼板のフォルステライト被膜（下地被膜）は、下地被膜表面をＥＰＭＡでマッピング分析したときのＯ強度の平均値に対する標準偏差の比率が０．１５以下の均一なものとなる。その結果、ＤＸガスのような反応性の高い雰囲気での歪取焼鈍でも、下地被膜が劣化せず、密着性に優れる被膜が得られる。なお、上記ＥＰＭＡのマッピング分析は、５０μｍ×５０μｍの領域を０．２μｍピッチで測定するものとする。 The forsterite coating (undercoating) of the grain-oriented electrical steel sheet produced in this manner has a uniform standard deviation ratio of 0.15 or less with respect to the average value of the O intensity when the undercoating surface is analyzed by mapping with EPMA. Becomes As a result, even under stress relief annealing in a highly reactive atmosphere such as DX gas, the underlying film does not deteriorate, and a film having excellent adhesion can be obtained. In the EPMA mapping analysis, a region of 50 μm × 50 μm is measured at a pitch of 0.2 μm.
上記仕上焼鈍後の鋼板は、その後、鋼板表面に付着した未反応の焼鈍分離剤を除去するための水洗やブラッシング、酸洗等を行った後、絶縁被膜を塗布し、この焼付けと形状矯正を兼ねた平坦化焼鈍を施して最終製品の方向性電磁鋼板とするのが好ましい。 The steel sheet after the finish annealing is then subjected to water washing or brushing for removing the unreacted annealing separator adhering to the steel sheet surface, pickling, etc., and then applying an insulating coating to correct the baking and shape correction. It is preferable that the grain-oriented electrical steel sheet of the final product is obtained by performing the flattening annealing that doubles as the above.
なお、製品板の鉄損をより低減するためには、磁区細分化処理を施すことが有効である。磁区細分化の方法としては、一般的に実施されている、最終製品板に溝を形成したり、レーザーや電子ビームを照射して線状または点状の熱歪や衝撃歪を導入する方法、最終板厚に冷間圧延した鋼板表面にエッチング加工を施して溝を形成したりする方法等を用いることができる。なお、本発明では、電子ビーム照射しても被膜が剥落することがない強固な被膜を形成することができるので、電子ビーム照射が好適である。 In addition, in order to further reduce the iron loss of the product plate, it is effective to perform the magnetic domain subdivision processing. As a method of subdividing magnetic domains, which is generally carried out, a groove is formed in the final product plate, or a method of irradiating a laser or an electron beam to introduce linear or point-like thermal strain or impact strain, It is possible to use a method in which the surface of the steel sheet cold-rolled to the final thickness is subjected to etching to form grooves. In the present invention, the electron beam irradiation is preferable because a strong film can be formed which does not peel off even when the electron beam irradiation is performed.
Ｃ：０．０７０ｍａｓｓ％、Ｓｉ：３．４ｍａｓｓ％、Ｍｎ：０．０８ｍａｓｓ％、Ａｌ：０．０２ｍａｓｓ％およびＮ：０．００８ｍａｓｓ％、残部がＦｅおよび不可避的不純物からなる鋼スラブを連続鋳造法で製造し、１３５０℃の温度に再加熱した後、熱間圧延して、板厚２．４ｍｍの熱延板とし、１０００℃×５０ｓの熱延板焼鈍を施した後、一次冷間圧延により１．８ｍｍの中間板厚とし、１１００℃×２０ｓの中間焼鈍を施した後、二次冷間圧延して最終板厚０．２３ｍｍの冷延板に仕上げた。
次いで、上記冷延板を脱脂し、酸洗した後、珪酸ナトリウム３０ｇ／Ｌ、界面活性剤５ｇ／Ｌと、種々の金属のＥＤＴＡ金属塩を添加した電解液を用いて、浴温７０℃、電流密度０．１〜２０Ａ／ｄｍ２で、電解時間を０〜１５ｓの範囲で種々に変化させて電解処理して金属粒子を鋼板表面に電着させた。この際、電解液の金属塩濃度および電解処理前の酸洗液濃度を種々に変えて、金属の析出状態を変化させた。
その後、上記冷延板を、５０ｖｏｌ％Ｈ２−５０ｖｏｌ％Ｎ２、露点５０〜６５℃の湿潤雰囲気下で、８４０℃の温度に１００ｓ間保持する、一次再結晶焼鈍を兼ねた脱炭焼鈍を施した。
次いで、ＭｇＯを主体とする焼鈍分離剤をスラリー状にして鋼板表面に塗布、乾燥した後、二次再結晶焼鈍後に１２００℃×１０ｈｒの純化処理を行う仕上焼鈍を施した。仕上焼鈍の雰囲気は、純化処理する１２００℃保定時はＨ２、昇温時（二次再結晶焼鈍を含む）および降温時はＮ２とした。その後、リン酸マグネシウム−コロイド状シリカを主成分とする絶縁被膜を塗布し、平坦化焼鈍で焼き付けて製品板とした。
C: 0.070mass%, Si: 3.4mass%, Mn: 0.08mass%, Al: 0.02mass% and N: 0.008mass%, the balance being a steel slab consisting of Fe and inevitable impurities, continuously cast. After reheating to a temperature of 1350 ° C., it is hot-rolled into a hot-rolled sheet having a thickness of 2.4 mm, subjected to hot-rolled sheet annealing at 1000 ° C. × 50 s, and then subjected to primary cold rolling. After having an intermediate plate thickness of 1.8 mm and performing intermediate annealing at 1100 ° C. for 20 s, secondary cold rolling was performed to finish a cold-rolled plate having a final plate thickness of 0.23 mm.
Next, after degreasing the above cold-rolled sheet and pickling it, sodium silicate 30 g / L, surfactant 5 g / L, and an electrolyte solution to which EDTA metal salts of various metals were added, bath temperature 70 ° C., At a current density of 0.1 to 20 A / dm 2 , the electrolysis time was variously changed within a range of 0 to 15 s, and electrolytic treatment was performed to electrodeposit metal particles on the surface of the steel sheet. At this time, the metal salt concentration of the electrolytic solution and the concentration of the pickling solution before the electrolytic treatment were variously changed to change the metal deposition state.
Then, decarburization annealing, which also serves as primary recrystallization annealing, is performed by maintaining the cold-rolled sheet at a temperature of 840 ° C. for 100 s in a humid atmosphere of 50 vol% H 2 -50 vol% N 2 and a dew point of 50 to 65 ° C. gave.
Next, an annealing separator mainly composed of MgO was made into a slurry, applied on the surface of the steel sheet, dried, and then subjected to secondary recrystallization annealing, followed by finish annealing in which a purification treatment of 1200 ° C. × 10 hr was performed. The atmosphere of the finish annealing was H 2 when the temperature was maintained at 1200 ° C. for the purification treatment, and N 2 when the temperature was raised (including secondary recrystallization annealing) and when the temperature was lowered. After that, an insulating coating containing magnesium phosphate-colloidal silica as a main component was applied and baked by flattening annealing to obtain a product plate.
上記のようにして得た製品板からサンプルを採取し、磁気特性と歪取焼鈍を施した後の曲げ密着性を評価した。
ここで、上記磁気特性は、ＪＩＳ Ｃ２５５０に規定された方法で、磁束密度Ｂ８および鉄損Ｗ１７／５０を測定した。
また、被膜の密着性は、８５０℃×３ｈｒのＤＸガス雰囲気（ＣＯ：１ｖｏｌ％＋Ｈ２：１ｖｏｌ％＋ＣＯ２：１２ｖｏｌ％＋残部：Ｎ２、露点１０℃）で歪取焼鈍を施した後、径の異なる丸棒に鋼板を巻き付けたときに被膜が剥離しなかった最小の径（曲げ剥離径）を測定した
A sample was taken from the product plate obtained as described above, and the magnetic properties and the bending adhesion after strain relief annealing were evaluated.
Here, with respect to the magnetic characteristics, the magnetic flux density B 8 and the iron loss W 17/50 were measured by the method specified in JIS C2550.
The adhesion of the coating, DX gas atmosphere 850 ℃ × 3hr (CO: 1vol % + H 2: 1vol% + CO 2: 12vol% + balance: N 2,
また、上記測定とは別に採取したサンプル表面の絶縁被膜をアルカリ洗浄して除去し、ＥＰＭＡで下地被膜表面の５０μｍ×５０μｍの領域を、０．２μｍピッチで、Ｏ濃度をマッピング分析し、得られたＯ強度の全測定データの平均値と標準偏差および平均値に対する標準偏差の比を求めた。
上記測定の結果を表１に示した。この表から、本発明に適合する鋼板は、いずれも磁気特性と被膜特性に優れていることがわかる。
In addition, the insulating coating on the surface of the sample collected separately from the above measurement was removed by alkali cleaning, and the area of 50 μm × 50 μm on the surface of the underlying coating was subjected to mapping analysis of O concentration at a pitch of 0.2 μm by EPMA. The average value and standard deviation of all measured O intensities and the ratio of the standard deviation to the average value were obtained.
The results of the above measurements are shown in Table 1. From this table, it can be seen that the steel sheets conforming to the present invention are all excellent in magnetic characteristics and coating characteristics.
表２にした各種成分組成を有し、残部がＦｅおよび不可避的不純物からなる鋼スラブを連続鋳造法で製造し、１３８０℃の温度に再加熱した後、熱間圧延して板厚２．０ｍｍの熱延板とし、１０３０℃×１０ｓの熱延板焼鈍を施した後、冷間圧延して最終板厚が０．２３ｍｍの冷延板に仕上げた。
次いで、上記冷延板を脱脂し、酸洗した後、水酸化ナトリウム３０ｇ／Ｌ、界面活性剤５ｇ／Ｌと、グルコン酸銅を添加した電解液を用いて、浴温７０℃、電流密度２Ａ／ｄｍ２で、電解時間を１ｓとする電解処理を施し、鋼板表面にＣｕを電着させた。この際、酸洗条件と電解浴のグルコン酸銅の濃度を種々に変えることで、電解後のＣｕ粒子の析出形態を種々に変化させた。
その後、５０ｖｏｌ％Ｈ２−５０ｖｏｌ％Ｎ２、露点５０〜６５℃の湿潤雰囲気下で、８４０℃の温度に１００ｓ間保持する、一次再結晶焼鈍を兼ねた脱炭焼鈍を施した後、ＭｇＯを主体とする焼鈍分離剤をスラリー状にして鋼板表面に塗布、乾燥し、その後、二次再結晶焼鈍後、１２００℃×１０ｈｒの純化処理を行う仕上焼鈍を施した。なお、仕上焼鈍の雰囲気は、純化処理する１２００℃保定時はＨ２、昇温時（二次再結晶焼鈍を含む）および降温時はＮ２とした。その後、リン酸マグネシウム−コロイド状シリカを主成分とする絶縁被膜塗布し、平坦化焼鈍で焼き付けて製品板とした。
A steel slab having the various component compositions shown in Table 2 and the balance being Fe and inevitable impurities was manufactured by a continuous casting method, reheated to a temperature of 1380 ° C., and then hot-rolled to a plate thickness of 2.0 mm. After hot-rolled sheet was annealed at 1030 ° C. × 10 s, it was cold-rolled to a cold-rolled sheet having a final thickness of 0.23 mm.
Next, after degreasing the cold-rolled sheet and pickling, using an electrolytic solution containing 30 g / L of sodium hydroxide, 5 g / L of a surfactant and copper gluconate, a bath temperature of 70 ° C. and a current density of 2 A Electrolysis treatment was performed at / dm 2 for an electrolysis time of 1 s, and Cu was electrodeposited on the surface of the steel sheet. At this time, by changing the pickling conditions and the concentration of copper gluconate in the electrolytic bath in various ways, the precipitation morphology of the Cu particles after electrolysis was variously changed.
After that, decarburization annealing that also serves as primary recrystallization annealing is performed at a temperature of 840 ° C. for 100 s in a humid atmosphere of 50 vol% H 2 -50 vol% N 2 and a dew point of 50 to 65 ° C., and then MgO is added. The annealing separator as a main component was made into a slurry and applied to the surface of the steel sheet, dried, and then subjected to secondary recrystallization annealing, and then finish annealing was performed at 1200 ° C. × 10 hr for purification treatment. The atmosphere of the finish annealing was H 2 when the temperature was maintained at 1200 ° C. for the purification treatment, and N 2 when the temperature was raised (including secondary recrystallization annealing) and when the temperature was lowered. After that, an insulating film containing magnesium phosphate-colloidal silica as a main component was applied and baked by flattening annealing to obtain a product plate.
上記のようにして得た製品板からサンプルを採取し、実施例１と同様にして、磁気特性と被膜密着性を評価した。同表から、本発明に適合する成分組成の鋼素材を用いることで、良好な磁気特性と被膜特性を有する方向性電磁鋼板を得ることができることがわかる。 Samples were taken from the product plate obtained as described above, and magnetic properties and coating adhesion were evaluated in the same manner as in Example 1. It can be seen from the table that a grain-oriented electrical steel sheet having good magnetic properties and coating properties can be obtained by using a steel material having a composition that complies with the present invention.
Claims (7)
フォルステライト質下地被膜を有する方向性電磁鋼板であって、
上記下地被膜表面をＥＰＭＡでマッピング分析したときのＯ強度の標準偏差が平均値の０．１５以下であることを特徴とする方向性電磁鋼板。 C: 0.005 mass% or less, Si: 2.5 to 4.5 mass% and Mn: 0.03 to 0.30 mass% are contained, and the balance has a composition of Fe and inevitable impurities.
A grain-oriented electrical steel sheet having a forsterite undercoat,
A grain-oriented electrical steel sheet, characterized in that the standard deviation of O intensity when mapping and analyzing the surface of the undercoat with EPMA is 0.15 or less of the average value.
上記最終板厚とする冷間圧延から脱炭焼鈍までの間において、鋼板表面に平均粒径が７０ｎｍ以下の金属粒子を２５個／μｍ２以上電着析出させることを特徴とする請求項１に記載の方向性電磁鋼板の製造方法。 A steel material containing C: 0.03 to 0.08 mass%, Si: 2.5 to 4.5 mass% and Mn: 0.03 to 0.30 mass% with the balance being Fe and inevitable impurities was hot-worked. Rolled into hot-rolled sheet, and after cold-rolled sheet annealing or without hot-rolled sheet annealing, cold-rolled once or twice or more with intermediate annealing sandwiched to obtain cold-rolled sheet with final thickness After the decarburization annealing that also serves as the primary recrystallization annealing, an annealing separator is applied to the steel sheet surface, and a method for producing a grain-oriented electrical steel sheet comprising a series of finish annealing steps,
In Until decarburization annealing the cold-rolled to the final thickness, the metal particles having an average particle diameter less 70nm on the surface of the steel sheet in claim 1, characterized in that deposit 25 / [mu] m 2 or more electrodeposition A method for manufacturing the grain-oriented electrical steel sheet described.
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