JP5920387B2 - Method for producing grain-oriented electrical steel sheet - Google Patents
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- 229910001224 Grain-oriented electrical steel Inorganic materials 0.000 title claims description 30
- 238000000137 annealing Methods 0.000 claims description 65
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- 229910000831 Steel Inorganic materials 0.000 claims description 48
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- GVALZJMUIHGIMD-UHFFFAOYSA-H magnesium phosphate Chemical compound [Mg+2].[Mg+2].[Mg+2].[O-]P([O-])([O-])=O.[O-]P([O-])([O-])=O GVALZJMUIHGIMD-UHFFFAOYSA-H 0.000 description 1
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Description
本発明は、トランスなどの鉄心材料に好適な方向性電磁鋼板の製造方法に関するものである。 The present invention relates to a method for producing a grain-oriented electrical steel sheet suitable for a core material such as a transformer.
方向性電磁鋼板は、主にトランスの鉄心材料として用いられる軟磁性材料で、鉄の磁化容易軸である＜001＞方位が鋼板の圧延方向に高度に揃った結晶組織を有するものである。このような集合組織は、方向性電磁鋼板の製造工程中、二次再結晶焼鈍の際にいわゆるゴス（Goss）方位と称される{110}<001>方位の結晶粒を優先的に巨大成長させる、二次再結晶を通じて形成される。 A grain-oriented electrical steel sheet is a soft magnetic material mainly used as a core material of a transformer and has a crystal structure in which the <001> orientation, which is the easy axis of iron, is highly aligned in the rolling direction of the steel sheet. Such a texture preferentially grows grains of the {110} <001> orientation called the Goss orientation during secondary recrystallization annealing during the production process of grain-oriented electrical steel sheets. Formed through secondary recrystallization.
従来、このような方向性電磁鋼板は、4.5mass％以下程度のSiと、MnS，MnSeおよびAlNなどのインヒビター成分を含有するスラブを、1300℃以上に加熱し、インヒビター成分を一旦固溶させたのち、熱間圧延し、必要に応じて熱延板焼鈍を施して、１回または中間焼鈍を挟む２回以上の冷間圧延によって最終板厚とし、ついで湿潤水素雰囲気中で一次再結晶焼純を施して、一次再結晶および脱炭を行い、ついでマグネシア（MgO）を主剤とする焼鈍分離剤を塗布してから、二次再結晶およびインヒビター成分の純化のために、1200℃で５ｈ程度の最終仕上焼鈍を行うことによって製造されてきた（例えば、特許文献１、特許文献２および特許文献３）。 Conventionally, such a grain-oriented electrical steel sheet is heated to 1300 ° C or higher by heating a slab containing about 4.5 mass% or less of Si and an inhibitor component such as MnS, MnSe, and AlN to once dissolve the inhibitor component. After that, it is hot-rolled and subjected to hot-rolled sheet annealing as necessary, to obtain the final sheet thickness by one or more cold rollings sandwiching intermediate annealing, followed by primary recrystallization annealing in a wet hydrogen atmosphere After performing primary recrystallization and decarburization, and then applying an annealing separator mainly composed of magnesia (MgO), the secondary recrystallization and the inhibitor component are purified at 1200 ° C. for about 5 hours. It has been manufactured by performing final finish annealing (for example, Patent Document 1, Patent Document 2, and Patent Document 3).
上述したとおり、従来の方向性電磁鋼板の製造に際しては、MnS，MnSe，AlNなどの析出物（インヒビター成分）をスラブ段階で含有させて、1300℃を超える高温のスラブ加熱をすることにより、これらのインヒビター成分を一旦固溶させ、後工程で微細析出させることによって二次再結晶を発現させるという工程が採用されてきた。 As described above, when manufacturing conventional grain-oriented electrical steel sheets, precipitates (inhibitor components) such as MnS, MnSe, and AlN are included in the slab stage, and these are heated at a high temperature exceeding 1300 ° C. The step of causing secondary recrystallization by once dissolving the inhibitor component of this compound and then precipitating it finely in a subsequent step has been adopted.
このように、従来の方向性電磁鋼板の製造工程では、1300℃を超える高温でのスラブ加熱が必要であったため、その製造コストは極めて高いものとならざるを得ず、近年の製造コスト低減の要求に応えることができないというところに問題を残していた。
また、特許文献４には、スラブにインヒビター成分を含有させない場合であっても、一次再結晶焼鈍後、二次再結晶完了前に、地鉄中のＳ量を増加させることによって、二次再結晶を発現させることができる技術（「増硫法」）が開示されている。しかしながら、上記技術は、増硫処理後、二次再結晶焼鈍の昇温過程から二次再結晶直前までに、鋼中に侵入したＳを均一に分散させることが難しく、二次再結晶自身が不安定となりがちであった。特に、コイル焼鈍を行った場合、コイル内における温度や鋼板層間の雰囲気を一定にすることが難しいため、二次再結晶の組織（方位）がよりばらつく傾向にあった。
As described above, in the manufacturing process of conventional grain-oriented electrical steel sheets, slab heating at a high temperature exceeding 1300 ° C. is necessary, so the manufacturing cost has to be extremely high, and in recent years the manufacturing cost has been reduced. He left a problem where he was unable to meet the demand.
Further, in Patent Document 4, even when the inhibitor component is not contained in the slab, the secondary recrystallization is performed by increasing the amount of S in the ground iron after the primary recrystallization annealing and before the completion of the secondary recrystallization. A technique (“sulfurization method”) capable of expressing crystals is disclosed. However, in the above technique, it is difficult to uniformly disperse S that has entered the steel from the temperature increasing process of the secondary recrystallization annealing to immediately before the secondary recrystallization after the vulcanization treatment. Tended to be unstable. In particular, when the coil annealing is performed, it is difficult to make the temperature in the coil and the atmosphere between the steel sheet layers constant, so that the structure (orientation) of secondary recrystallization tends to vary.
こうした問題を解決するために、例えば、特許文献５では、酸可溶性Al（sol.Al）を0.010〜0.060％含有させ、スラブ加熱を低温に抑えて脱炭焼鈍工程で適正な窒化雰囲気を用いて窒化を行なうことにより、二次再結晶時に（Al，Si）Nを析出させインヒビターとして用いる方法が提案されている。
（Al，Si）Nは鋼中に微細分散することで有効なインヒビターとして機能するが、Alの含有量によってインヒビター強度が決まるために、製鋼でのAl的中精度が不十分な場合は、十分な粒成長抑制力が得られない場合があった。このような途中工程で窒化処理を行ない、（Al，Si）NあるいはAlNをインヒビターとして利用する方法は数多く提案されているが、最近では、スラブ加熱温度が1300℃を超える製造方法等も開示されている。
In order to solve such a problem, for example, in Patent Document 5, 0.010 to 0.060% of acid-soluble Al (sol. Al) is contained, slab heating is suppressed to a low temperature, and an appropriate nitriding atmosphere is used in the decarburization annealing process. A method has been proposed in which (Al, Si) N is precipitated during secondary recrystallization by nitriding and used as an inhibitor.
(Al, Si) N functions as an effective inhibitor by being finely dispersed in the steel, but since the inhibitor strength is determined by the Al content, it is sufficient if the accuracy of Al in steelmaking is insufficient. In some cases, it was not possible to obtain a sufficient grain growth inhibiting force. Many methods have been proposed to perform nitriding in such an intermediate process and use (Al, Si) N or AlN as an inhibitor, but recently, a manufacturing method in which the slab heating temperature exceeds 1300 ° C has also been disclosed. ing.
一方、そもそもスラブにインヒビター成分を含有させずに二次再結晶を発現させる技術については、特許文献６に、インヒビター成分を含有させなくとも二次再結晶ができる技術（インヒビターレス法）が開示されている。
ここに、インヒビターレス法は、より高純度化した鋼を利用し、テクスチャー（集合組織の制御）によって二次再結晶を発現させる技術である。しかしながら、インヒビターレス法では、高温のスラブ加熱が不要であって、低コストでの方向性電磁鋼板の製造が可能であるものの、インヒビターを有しないが故に、製造工程中での温度ばらつきなどの影響を受けて、製品での磁気特性にバラつきが生じやすいといった不利があった。
On the other hand, regarding a technique for expressing secondary recrystallization without containing an inhibitor component in the slab, Patent Document 6 discloses a technique (inhibitorless method) that enables secondary recrystallization without containing an inhibitor component. ing.
Here, the inhibitorless method is a technique in which secondary recrystallization is manifested by texture (control of texture) using higher-purity steel. However, the inhibitorless method does not require high-temperature slab heating and enables production of grain-oriented electrical steel sheets at a low cost. As a result, there is a disadvantage that the magnetic characteristics of the product are likely to vary.
また、集合組織の制御は、磁気特性に対して重要な要素であるため、集合組織制御を行う温間圧延などには、多くの条件が提案されている。しかしながら、こうした集合組織制御が十分に行なえない場合は、インヒビターを用いる技術に比べると、二次再結晶後のゴス方位（{110}<001>）への集積度が低く、磁束密度も低くなってしまうといった不利があった。 In addition, since texture control is an important factor for magnetic properties, many conditions have been proposed for warm rolling and the like in which texture control is performed. However, if such texture control cannot be performed sufficiently, the degree of integration in the Goth orientation ({110} <001>) after secondary recrystallization is low and the magnetic flux density is low compared to the technique using inhibitors. There was a disadvantage such as.
上述したとおり、これまで提案されてきた方向性電磁鋼板の製造方法では、良好な磁気特性を安定的に実現することが難しい場合が多かった。
これに対し、発明者らは、スラブ加熱温度を抑えつつ、磁気特性のバラつきを低減した方向性電磁鋼板を製造するために、インヒビター成分を含有させない方向性電磁鋼板の製造方法を用いて一次再結晶集合組織の作り込みを行ない、これに途中工程で窒化を利用して窒化珪素（Si3N4）を析出させ、この窒化珪素をインヒビターとして利用することを検討した。
As described above, it has often been difficult to stably achieve good magnetic properties in the method of manufacturing grain-oriented electrical steel sheets that has been proposed so far.
In contrast, in order to manufacture a grain-oriented electrical steel sheet with reduced variation in magnetic properties while suppressing the slab heating temperature, the inventors have used a method for producing a grain-oriented electrical steel sheet that does not contain an inhibitor component to perform primary regeneration. A crystal texture was formed, and silicon nitride (Si 3 N 4 ) was deposited using nitridation in the middle of the process, and the use of this silicon nitride as an inhibitor was investigated.
すなわち、表層窒素濃化層からの窒素の粒界拡散の挙動と、窒化珪素の析出挙動の詳細な検討により、Alを100ppm未満に抑制したインヒビターレス成分に準じた成分を用いて、高温スラブ加熱を回避しつつ、窒素増量を適用することで、AlNではなく窒化珪素を析出させ、この窒化珪素を正常粒成長の抑制力として機能させることで、磁気特性のバラつきを大幅に低減し、工業的に安定して良好な特性を有する方向性電磁鋼板を製造する方法である。 That is, high-temperature slab heating using a component in accordance with an inhibitorless component in which Al is suppressed to less than 100 ppm by detailed examination of the grain boundary diffusion behavior of nitrogen from the surface nitrogen enriched layer and the precipitation behavior of silicon nitride By applying nitrogen increase, silicon nitride is precipitated instead of AlN, and this silicon nitride functions as a suppressive force for normal grain growth, greatly reducing the variation in magnetic properties and industrial. It is a method for producing a grain-oriented electrical steel sheet having good and stable characteristics.
ところで、電磁鋼の熱延板に中間焼鈍を挟む２回の冷間圧延を施して最終板厚とした後、脱炭焼鈍、次いで焼鈍分離剤を塗布してから仕上げ焼鈍を施す一連の方向性電磁鋼板の製造工程中、冷間圧延を行う際、従来より使用されている冷間圧延設備としては大きく分けて２つある。
その一つは、小径ワークロールを適用する多段圧延機であって、なかでもゼンジミア圧延機が多く使用されている。もう一つはタンデム圧延機であって、これは特許文献７に開示されているように、電磁鋼板を高能率で製造することができる。
By the way, a series of orientations in which hot rolling of electromagnetic steel is cold-rolled twice with intermediate annealing to obtain the final sheet thickness, followed by decarburization annealing and then applying annealing separator and then finishing annealing. When performing cold rolling during the manufacturing process of the electrical steel sheet, there are roughly two types of cold rolling equipment conventionally used.
One of them is a multi-high rolling mill to which a small-diameter work roll is applied, and among them, a Sendzimir rolling mill is often used. The other is a tandem rolling mill, which can produce an electromagnetic steel sheet with high efficiency as disclosed in Patent Document 7.
タンデム圧延は、上述したように高能率で製造できるというメリットがあるものの、タンデム圧延した電磁鋼板は、種々の要因によりゼンジミアミル等の小径ワークロールで圧延した電磁鋼板よりも電磁特性が劣っていた。というのは、高速圧延によって圧延油のロールバイトヘの導入量が増大した場合、これに起因して圧延油が鋼板とロールとの間に封入され、圧延時に鋼板表面を押しつぶす現象が生じるが、この現象により、鋼板表面にはオイルピットと呼ばれる局所的な凹凸が発生して、鋼板の表面性状を劣化させ、引き続いて行われる一次再結晶焼鈍で、鋼板表面に形成されるファイアライトとシリカを主体としたサブスケール性状が大きな影響を受けるためと推定されるからである。
さらに、二次再結晶におけるゴス方位の選択性を左右する集合組織の効果的な形成の観点からも、小径ワークロールを適用するゼンジミア圧延は有利と考えられてきた。
Although tandem rolling has the merit that it can be manufactured with high efficiency as described above, the electromagnetic steel sheet rolled by tandem has inferior electromagnetic characteristics than the electromagnetic steel sheet rolled by a small diameter work roll such as a Sendzimir mill due to various factors. Because, when the amount of rolling oil introduced into the roll bite is increased by high-speed rolling, the rolling oil is enclosed between the steel sheet and the roll due to this, and the phenomenon of crushing the steel sheet surface during rolling occurs. Due to this phenomenon, local irregularities called oil pits are generated on the steel sheet surface, which deteriorates the surface properties of the steel sheet, and the subsequent recrystallization annealing causes the firelight and silica formed on the steel sheet surface. This is because it is presumed that the main subscale properties are greatly affected.
Further, from the viewpoint of effective formation of a texture that affects the selectivity of Goss orientation in secondary recrystallization, Sendzimir rolling using a small-diameter work roll has been considered advantageous.
このように、電磁鋼板を製造する際の冷間圧延段階において、生産性向上のためにタンデム圧延を行う場合には、圧延板の表面粗さや集合組織形成に関する課題があり、結果的に、磁気特性がゼンジミアミルを用いた小径圧延に比べて劣っているという問題が生じていた。 Thus, when performing tandem rolling to improve productivity in the cold rolling stage when manufacturing electrical steel sheets, there are problems related to surface roughness and texture formation of the rolled sheets, resulting in magnetic There has been a problem that the characteristics are inferior to those of small diameter rolling using a Sendzimir mill.
一方で、特許文献８には、タンデム圧延と熱延巻取り温度の制御などにより、AlN インヒビターを用いた成分系で、比較的良好な特性を得ているが、AlN をインヒビターとして用いる場合に必須の、製鋼でのAl量の的中精度にばらつきがあり、磁気特性が劣化する場合があった。 On the other hand, in Patent Document 8, comparatively good characteristics are obtained in a component system using an AlN inhibitor by controlling tandem rolling and hot rolling coiling temperature, but it is essential when using AlN as an inhibitor. However, there was a variation in the accuracy of the amount of Al in steel making, and the magnetic characteristics sometimes deteriorated.
発明者らは、前述したように、窒化を適用することで窒化珪素を析出させて安定した方向性電磁鋼板の製造方法を見出したが、これを有利に実施するにあたり、圧延温度、圧延速度やワークロール粗度、ワークロール径等を検討し、最適な冷間圧延組織を模索した結果、本発明に至った。 As described above, the inventors have found a method for producing a stable grain-oriented electrical steel sheet by precipitating silicon nitride by applying nitriding, but in carrying out this advantageously, the rolling temperature, rolling speed, As a result of examining the work roll roughness, the work roll diameter, and the like and searching for an optimal cold rolling structure, the present invention has been achieved.
本発明は、上記の知見に基づき開発されたもので、窒化珪素を形成する目的で二次再結晶前の鋼板に窒素を加えた方向性電磁鋼板に対し、窒素を鋼中へ効率的に拡散させ、窒化珪素を粒界に析出させることで、良好な磁気特性を有する方向性電磁鋼板が得られる方向性電磁鋼板の製造方法を提供することを目的とする。 The present invention was developed on the basis of the above knowledge. Nitrogen is efficiently diffused into steel in a directional electrical steel sheet in which nitrogen is added to a steel sheet before secondary recrystallization for the purpose of forming silicon nitride. It is an object of the present invention to provide a method for producing a grain-oriented electrical steel sheet in which a grain-oriented electrical steel sheet having good magnetic properties is obtained by precipitating silicon nitride at grain boundaries.
まず、本発明を完成するに至った実験結果について説明する。
質量％または質量ppmで、Ｃ：600ppm、Si：3.30％、Mn：0.08％、Ｓ：10ppm、Al：20ppm、Ｎ：20ppm、Sb：0.01％およびCu：0.05％を含み、残部はFeおよび不可避的不純物の組成からなる鋼スラブを、連続鋳造後、1100℃に加熱したのち、熱間圧延によって2.2mm厚の熱延板とし、ついで1000℃にて熱延板焼鈍を施したのち、酸洗して冷間圧延により0.23mmの厚みに仕上げた。
この時、タンデム圧延機とゼンジミア圧延機と二つの圧延機を用い、かつクーラント量を増やして鋼板表面に噴射することで、圧延温度を80℃前後に抑えた冷間圧延と、加工発熱またはパス間時効により最終圧延時に200℃前後まで温度上昇した温間圧延をそれぞれ行い、計４条件を実施した。
First, the experimental results that led to the completion of the present invention will be described.
In mass% or mass ppm, C: 600ppm, Si: 3.30%, Mn: 0.08%, S: 10ppm, Al: 20ppm, N: 20ppm, Sb: 0.01% and Cu: 0.05%, the balance being Fe and inevitable After continuous casting, the steel slab with the composition of mechanical impurities is heated to 1100 ° C, then hot-rolled to a 2.2mm thick hot-rolled sheet, then hot-rolled sheet annealed at 1000 ° C, and then pickled Then, it was finished to a thickness of 0.23 mm by cold rolling.
At this time, using a tandem mill, a Sendzimir mill and two rolling mills, and increasing the amount of coolant and injecting it onto the steel sheet surface, cold rolling with a rolling temperature suppressed to around 80 ° C, processing heat generation or pass A total of four conditions were carried out, each of which was warm-rolled to about 200 ° C. during final rolling due to inter-aging.
また、最終板厚に仕上げる圧延速度を200rpm未満とする低速圧延と、600rpmより大きくする高速圧延の二条件を実施することで圧延速度の影響についても検討した。さらにワークロールの摩耗を利用して、ワークロール径の影響についても調査した。 In addition, the effect of the rolling speed was examined by implementing two conditions, a low speed rolling with a final sheet thickness of less than 200 rpm and a high speed rolling with a speed greater than 600 rpm. Furthermore, the influence of the work roll diameter was investigated using the wear of the work roll.
最終板厚である0.23mmに仕上げた後、各コイルを脱脂して850℃の湿水素雰囲気で脱炭焼鈍を行い、得られた脱炭焼鈍板より圧延方向に沿ってエプスタイン試料を冷間圧延条件ごとに切り出した。
引き続き、500℃の塩浴炉にてΔＮ＝300ppmの増窒処理を行った。その後、MgOを主剤とした焼鈍分離剤を鋼板に塗布し、1150℃で５時間の最終仕上げ焼鈍を行った。最終仕上げ焼鈍の雰囲気ガスとして、昇温中はＮ２ガス、1150℃到達後はＨ２ガスを用いて純化処理を行った。その後、未反応分離剤を除去した後、コロイダルシリカとリン酸Mgを主体とする絶縁コーティングを850℃で形成して製品板とした。
After finishing to a final thickness of 0.23 mm, each coil is degreased and decarburized and annealed in a humid hydrogen atmosphere at 850 ° C, and the Epstein sample is cold-rolled along the rolling direction from the obtained decarburized and annealed sheet Cut out for each condition.
Subsequently, a nitrogen increase treatment of ΔN = 300 ppm was performed in a salt bath furnace at 500 ° C. Thereafter, an annealing separator containing MgO as a main component was applied to the steel sheet, and a final finish annealing was performed at 1150 ° C. for 5 hours. As atmosphere gas for final finish annealing, purification was performed using N 2 gas during the temperature rise and H 2 gas after reaching 1150 ° C. Then, after removing the unreacted separating agent, an insulating coating mainly composed of colloidal silica and Mg phosphate was formed at 850 ° C. to obtain a product plate.
かかる製品板のエプスタイン試料に対し、それぞれ、磁束密度1.7Ｔ、周波数50Hzにおける鉄損値Ｗ17/50（W/kg）および磁束密度Ｂ８（Ｔ）を測定した。この測定結果のうち、ワークロール径を横軸、磁束密度Ｂ８を縦軸として図１にプロットした。 The iron loss value W 17/50 (W / kg) and the magnetic flux density B 8 (T) at a magnetic flux density of 1.7 T, a frequency of 50 Hz were measured for the Epstein samples of the product plate. Of these measurement results, the work roll diameter was plotted on the horizontal axis and the magnetic flux density B 8 was plotted on the vertical axis in FIG.
図１に示したとおり、低Alのインヒビター成分を含まない成分系に対して、増窒処理を施して二次再結晶させる場合には、冷間圧延のワークロール径の影響が最も大きくなり、ワークロール径が250mm以上の条件で、高い磁束密度が得られることが分かった。
本発明は上記知見に立脚するものである。
As shown in FIG. 1, when the secondary recrystallization is performed by increasing the nitrogen concentration for the component system that does not contain the low Al inhibitor component, the influence of the cold rolling work roll diameter is the largest, It was found that high magnetic flux density can be obtained under the condition that the work roll diameter is 250 mm or more.
The present invention is based on the above findings.
本発明の要旨構成は次のとおりである。
１．質量％で、Ｃ：0.08％以下、Si：2.0〜4.5％およびMn：0.5％以下を含有すると共に、Ｓ、SeおよびＯをそれぞれ50質量ppm未満、sol.Alを100質量ppm以下、Ｎを80質量ppm以下に抑制し、残部はFeおよび不可避的不純物の組成になる鋼スラブを、再加熱することなくあるいは再加熱後、1300℃以下で熱間圧延し、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、一回の冷間圧延で最終板厚の冷間圧延板とし、さらに、一次再結晶焼鈍を施して焼鈍分離剤を塗布し、二次再結晶焼鈍を施す一連の方向性電磁鋼板の製造工程において、
上記冷間圧延時のワークロール径を320mm以上とし、
さらに、上記一次再結晶焼鈍中、焼鈍後のいずれかでかつ、上記二次再結晶焼鈍前のタイミングで、加熱温度：800℃以下、また、加熱温度：800℃超の場合には保持時間：30秒以下として、窒素増量（ΔＮ）が50質量ppm以上1000質量ppm以下となる窒化処理を施し、
また、上記二次再結晶焼鈍における300〜800℃間の滞留時間を５時間以上150時間以下とする、方向性電磁鋼板の製造方法。
The gist of the present invention is as follows.
1. In mass%, C: 0.08% or less, Si: 2.0 to 4.5% and Mn: 0.5% or less, S, Se and O are each less than 50 mass ppm, sol.Al is 100 mass ppm or less, and N is After the steel slab, which is controlled to 80 mass ppm or less and the balance is Fe and inevitable impurities, without reheating or after reheating, is hot-rolled at 1300 ° C or less and subjected to hot-rolled sheet annealing Alternatively, without performing hot-rolled sheet annealing, a cold-rolled sheet with the final thickness is obtained by a single cold rolling, and further, a primary recrystallization annealing is applied and an annealing separator is applied, and a secondary recrystallization annealing is performed. In the manufacturing process of a series of grain-oriented electrical steel sheets to be applied,
The diameter of the work roll at the time of the cold rolling is 320 mm or more,
Furthermore, during the primary recrystallization annealing, either after annealing , and at the timing before the secondary recrystallization annealing , the heating temperature: 800 ° C. or less, and the heating temperature: more than 800 ° C., the holding time: as less than 30 seconds, nitrogen increased (.DELTA.N) is facilities nitrided equal to or less than 50 mass ppm to 1000 ppm by weight,
Moreover, the manufacturing method of a grain- oriented electrical steel sheet which sets the residence time between 300-800 degreeC in the said secondary recrystallization annealing to 5 hours or more and 150 hours or less .
２．前記冷間圧延をタンデム圧延機で行う前記１に記載の磁気特性に優れた方向性電磁鋼板の製造方法。 2. 2. The method for producing a grain-oriented electrical steel sheet having excellent magnetic properties according to 1 above, wherein the cold rolling is performed with a tandem rolling mill.
３．さらに、前記鋼スラブが、質量％で、
Ni：0.005〜1.50％、
Sn：0.01〜0.50％、
Sb：0.005〜0.50％、
Cu：0.01〜0.50％、
Cr：0.01〜1.50％、
Ｐ：0.0050〜0.50％、
Mo：0.01〜0.50％および
Nb：0.0005〜0.0100％
のうちから選んだ１種または２種以上を含有することを特徴とする前記１または２に記載の方向性電磁鋼板の製造方法。
3. Furthermore, the said steel slab is mass%,
Ni: 0.005-1.50%,
Sn: 0.01 to 0.50%,
Sb: 0.005-0.50%,
Cu: 0.01 to 0.50%,
Cr: 0.01 to 1.50%,
P: 0.0050 to 0.50%,
Mo: 0.01-0.50% and
Nb: 0.0005-0.0100%
The method for producing a grain-oriented electrical steel sheet according to 1 or 2 above, comprising one or more selected from among the above.
本発明によれば、高温スラブ加熱を施さずとも、磁気特性のバラつきが大幅に低減され、工業的に安定して良好な特性を有する方向性電磁鋼板を得ることができる。 According to the present invention, even if high temperature slab heating is not performed, the magnetic property variation is greatly reduced, and a grain-oriented electrical steel sheet having industrially stable and good characteristics can be obtained.
以下、本発明おける製造に関するポイントについて述べる。
本発明においては、基本的に従来公知のスラブ高温加熱を利用しない方向性電磁鋼板の製造方法に従う。
まず、本発明において、鋼スラブの成分組成の限定理由について説明する。なお、以下に記載する「％」および「ppm」表示は特に断らない限り、それぞれ質量％および質量ppmを意味するものとする。
Hereafter, the point regarding manufacture in this invention is described.
In the present invention, basically, a conventionally known method for producing grain-oriented electrical steel sheets that does not utilize high-temperature slab heating is followed.
First, the reason for limiting the component composition of the steel slab in the present invention will be described. Unless otherwise specified, “%” and “ppm” described below mean mass% and mass ppm, respectively.
本発明の溶鋼成分については、鋼溶製時にsol.Alを100ppm以下に抑制する。本発明は、AlNをインヒビターとして利用しないプロセスを前提として1300℃以下のスラブ加熱温度を想定しているので、sol.Alが100ppmより多い場合、AlN等として完全固溶できずに、粗大な析出物として二次再結晶の撹乱要因となる。従って、Alを100ppm以下に抑制する必要がある。 About the molten steel component of this invention, sol.Al is suppressed to 100 ppm or less at the time of steel melting. Since the present invention assumes a slab heating temperature of 1300 ° C. or less on the premise of a process that does not use AlN as an inhibitor, when sol.Al is more than 100 ppm, it cannot be completely dissolved as AlN or the like, and coarse precipitation It becomes a disturbance factor of secondary recrystallization as a product. Therefore, it is necessary to suppress Al to 100 ppm or less.
本発明は、増窒処理後にSi3N4を析出させることが重要であるため、不可避的に含まれるAl成分によってAlNが析出すると、後の析出物制御を乱す要因となるので、極力少ない方が良い。また、スラブ加熱時のフクレなどの欠陥の原因となることもあるため、80ppm以下に抑制することが好ましい。 In the present invention, since it is important to deposit Si 3 N 4 after the nitriding treatment, if AlN is inevitably deposited by the Al component contained, it will be a factor that disturbs the subsequent precipitate control, so the less Is good. Moreover, since it may cause defects such as blisters during slab heating, it is preferably suppressed to 80 ppm or less.
Ｃ:0.08％以下
Ｃは、一次再結晶集合組織を改善する上で有用な元素であるが、含有量が0.08％を超えると、かえって一次再結晶集合組織の劣化を招くので、本発明では0.08％以下に限定した。磁気特性の観点から望ましい添加量は、0.01〜0.06％の範囲である。なお、下限に関しては、磁気特性上30ppm程度以下が求められるので、要求される磁気特性のレベルがさほど高くない場合には、特に設けなくてもよい。
C: 0.08% or less C is an element useful for improving the primary recrystallization texture. However, if the content exceeds 0.08%, the primary recrystallization texture is deteriorated. % Or less. A desirable addition amount from the viewpoint of magnetic properties is in the range of 0.01 to 0.06%. Note that the lower limit is required to be about 30 ppm or less in terms of magnetic characteristics. Therefore, when the required level of magnetic characteristics is not so high, it is not particularly necessary.
Si:2.0〜4.5％
Siは、鋼の電気抵抗を高め、鉄損を改善するのに有効な元素であるが、含有量が2.0％に満たないとその添加効果に乏しく、一方、4.5％を超えると加工性が著しく低下し、また磁束密度も低下するため、Si量は2.0〜4.5％の範囲とする必要がある。
Si: 2.0-4.5%
Si is an element effective in increasing the electrical resistance of steel and improving iron loss. However, if its content is less than 2.0%, its additive effect is poor. On the other hand, if it exceeds 4.5%, the workability is remarkably high. The amount of Si needs to be in the range of 2.0 to 4.5% because the magnetic flux density also decreases.
Mn:0.5％以下
Mnは、製造時における熱間加工性を向上させる効果があるので、0.005％以上含有させることが好ましいが、含有量が0.5％を超えた場合には、一次再結晶集合組織が悪化して磁気特性の劣化を招くので、Mnは0.5％以下に限定した。
Mn: 0.5% or less
Since Mn has the effect of improving hot workability during production, it is preferable to contain 0.005% or more. However, if the content exceeds 0.5%, the primary recrystallization texture deteriorates and magnetic properties are increased. Since the characteristics are deteriorated, Mn is limited to 0.5% or less.
Ｓ，SeおよびＯ:それぞれ50ppm未満
先に述べたように、本発明では、Alを低減しているため、AlNを主体とする、いわゆるインヒビターの活用はない。この場合、磁束密度の高い方向性電磁鋼板を得るためには、Ｓ：50ppm（0.005％）未満、Se：50ppm（0.005％）未満とする必要がある。これは強い抑制力を発揮するインヒビター成分が含まれていない鋼成分系では、不純物による一次再結晶における粒成長性への影響が大きいためである。
また、Ｏ量は、50ppm（0.005％）未満とする必要がある。これは介在物としての酸化物が磁気特性に悪影響を及ぼすためである。
S, Se and O: each less than 50 ppm As described above, in the present invention, since Al is reduced, there is no utilization of a so-called inhibitor mainly composed of AlN. In this case, in order to obtain a grain-oriented electrical steel sheet having a high magnetic flux density, S: less than 50 ppm (0.005%) and Se: less than 50 ppm (0.005%) are required. This is because, in a steel component system that does not contain an inhibitor component that exhibits a strong suppressive force, the effect of impurities on the grain growth in primary recrystallization is large.
Further, the amount of O needs to be less than 50 ppm (0.005%). This is because oxides as inclusions adversely affect the magnetic properties.
ここで、Ｓ量は、磁束密度向上の観点から添加量が多いほど良好であるが、低温スラブ加熱を行う場合、MnS等のインヒビターとして制御性良く析出させることが困難なため、製鋼段階から添加すべきではなく、一次再結晶焼鈍後から二次再結晶完了までの間に、鋼板に対して増硫処理を施して増加させることが望ましい。また、このようなタイミングで増硫処理を施したとしても、二次再結晶焼鈍はバッチ式で焼鈍処理を行うため、昇温速度は一般に遅く、増硫処理により鋼中に侵入したＳを均一に分散させるのに適しているので問題はない。 Here, the amount of S is better as the added amount is larger from the viewpoint of improving the magnetic flux density. However, when performing low-temperature slab heating, it is difficult to precipitate as an inhibitor such as MnS with good controllability. It should not be increased, and it is desirable to increase the steel sheet by performing a vulcanization treatment after the primary recrystallization annealing until the completion of the secondary recrystallization. Moreover, even if the vulcanization treatment is performed at such timing, since the secondary recrystallization annealing is performed in a batch manner, the rate of temperature rise is generally slow, and the S that has penetrated into the steel by the vulcanization treatment is uniform. There is no problem because it is suitable for dispersion.
Ｎ:80ppm以下
本発明は、インヒビターレスの製造方法を適用し集合組織の作り込みまでを行なうため、Ｎは80ppm以下に抑制する必要がある。80ppmを超えると粒界偏析の影響や微量窒化物の形成により、集合組織が劣化するといった弊害が生じるからである。また、スラブ加熱時の「フクレ」などの欠陥の原因となることもあるため、80ppm以下に抑制する必要がある。なお、望ましくは60ppm以下である。
N: 80 ppm or less In the present invention, an inhibitorless manufacturing method is applied to complete the formation of a texture. Therefore, N must be suppressed to 80 ppm or less. This is because if it exceeds 80 ppm, the effect of grain boundary segregation and the formation of a trace amount of nitrides will cause the adverse effect of deterioration of the texture. Moreover, since it may cause defects such as “fluff” at the time of slab heating, it is necessary to suppress it to 80 ppm or less. Desirably, it is 60 ppm or less.
以上、必須成分について説明したが、本発明では、工業的により安定して磁気特性を改善する成分として、以下の元素を適宜含有させることができる。なお、残部は、Feおよび不可避的不純物である。
Ni:0.005〜1.50％
Niは、熱延板組織の均一性を高めることにより、磁気特性を改善する働きがあって、そのためには0.005％以上含有させることが好ましいが、含有量が1.50％を超えると所望の二次再結晶を得ることが困難となり、磁気特性が劣化するので、Niは0.005〜1.50％の範囲で含有させることが望ましい。
The essential components have been described above. In the present invention, the following elements can be appropriately contained as components that improve the magnetic properties more stably industrially. The balance is Fe and inevitable impurities.
Ni: 0.005-1.50%
Ni works to improve the magnetic properties by increasing the uniformity of the hot-rolled sheet structure, and for that purpose, it is preferable to contain 0.005% or more, but if the content exceeds 1.50%, the desired secondary Since it becomes difficult to obtain recrystallization and the magnetic properties deteriorate, it is desirable to contain Ni in the range of 0.005 to 1.50%.
Sn:0.01〜0.50％
Snは、二次再結晶焼鈍中の鋼板の窒化や酸化を抑制し、良好な結晶方位を有する結晶粒の二次再結晶を促進して磁気特性を向上させる有用元素であり、そのためには0.01％以上含有させることが好ましいが、0.50％を超えて含有されると冷間圧延性が劣化するので、Snは0.01〜0.50％の範囲で含有させることが望ましい。
Sn: 0.01-0.50%
Sn is a useful element that suppresses nitriding and oxidation of steel sheets during secondary recrystallization annealing and promotes secondary recrystallization of grains having good crystal orientation to improve magnetic properties. However, if it exceeds 0.50%, the cold rolling property deteriorates, so it is desirable to contain Sn in the range of 0.01 to 0.50%.
Sb:0.005〜0.50％
Sbは、二次再結晶焼鈍中の鋼板の窒化や酸化を抑制し、良好な結晶方位を有する結晶粒の二次再結晶を促進して磁気特性を効果的に向上させる有用元素であり、その目的のためには0.005％以上含有させることが好ましいが、0.50％を超えて含有されると冷間圧延性が劣化するので、Sbは0.005〜0.50％の範囲で含有させることが望ましい。
Sb: 0.005-0.50%
Sb is a useful element that effectively suppresses nitridation and oxidation of steel sheets during secondary recrystallization annealing, promotes secondary recrystallization of grains with good crystal orientation, and effectively improves magnetic properties. For the purpose, it is preferable to contain 0.005% or more, but if it exceeds 0.50%, the cold rolling property deteriorates, so Sb is preferably contained in the range of 0.005 to 0.50%.
Cu:0.01〜0.50％
Cuは、二次再結晶焼鈍中の鋼板の酸化を抑制し、良好な結晶方位を有する結晶粒の二次再結晶を促進して磁気特性を効果的に向上させる働きがあり、そのためには0.01％以上含有させることが好ましいが、0.50％を超えて含有されると熱間圧延性の劣化を招くので、Cuは0.01〜0.50％の範囲で含有させることが望ましい。
Cu: 0.01-0.50%
Cu suppresses oxidation of the steel sheet during secondary recrystallization annealing, promotes secondary recrystallization of grains having a good crystal orientation, and effectively improves magnetic properties. However, if it exceeds 0.50%, the hot rolling property is deteriorated, so it is desirable to contain Cu in the range of 0.01 to 0.50%.
Cr:0.01〜1.50％
Crは、フォルステライト被膜の形成を安定化させる働きがあり、そのためには0.01％以上含有させることが好ましいが、一方でその含有量が1.50％を超えると所望の二次再結晶を得ることが困難となり、磁気特性が劣化するので、Crは0.01〜1.50％の範囲で含有させることが望ましい。
Cr: 0.01 to 1.50%
Cr has a function of stabilizing the formation of the forsterite film, and for that purpose, it is preferable to contain 0.01% or more, but when the content exceeds 1.50%, a desired secondary recrystallization can be obtained. Since it becomes difficult and the magnetic properties deteriorate, it is desirable to contain Cr in the range of 0.01 to 1.50%.
Ｐ:0.0050〜0.50％
Ｐは、フォルステライト被膜の形成を安定化させる働きがあり、そのためには0.0050％以上含有させることが好ましいが、含有量が0.50％を超えると冷間圧延性が劣化するので、Ｐは0.0050〜0.50％の範囲で含有させることが望ましい。
P: 0.0050 ~ 0.50%
P has a function of stabilizing the formation of the forsterite film. For that purpose, P is preferably contained in an amount of 0.0050% or more. However, if the content exceeds 0.50%, the cold rolling property deteriorates, so P is 0.0050 to It is desirable to make it contain in 0.50% of range.
Mo:0.01〜0.50％、Nb:0.0005〜0.0100％
MoおよびNbは、スラブ加熱時の温度変化による割れの抑制等を介して、熱延後のヘゲを抑制する効果を有している。これらの元素は、少なくともどちらか一方を、上記下限値以上含有させなければヘゲ抑制の効果は小さく、一方、どちらかが上記上限を超えると、炭化物や窒化物を形成するなどして最終製品まで残留した際、鉄損劣化を引き起こすため、上述した範囲とすることが望ましい。
Mo: 0.01-0.50%, Nb: 0.0005-0.0100%
Mo and Nb have an effect of suppressing sag after hot rolling through suppression of cracking due to temperature change during slab heating. If these elements do not contain at least one of the above lower limit value or more, the effect of suppressing heges is small. On the other hand, if either of these elements exceeds the above upper limit, carbide or nitride is formed, and the final product. In order to cause deterioration of the iron loss when remaining up to, it is desirable to be in the above range.
次に、本発明の製造方法について説明する。
上記の好適成分組成範囲に調整した鋼スラブを、再加熱することなくあるいは再加熱したのち、熱間圧延に供する。なお、スラブを再加熱する場合には、再加熱温度を、1000℃程度以上とするのが望ましく1300℃以下とすることが必要である。というのは、1300℃を超えるスラブ加熱は、スラブの段階で鋼中にインヒビターをほとんど含まない本発明にとって無意味であり、コストアップの要因となるだけだからである。一方、1000℃未満のスラブ加熱では、熱間圧延時の圧延荷重が高くなって、圧延することが困難になるからである。
Next, the manufacturing method of this invention is demonstrated.
The steel slab adjusted to the above preferable component composition range is subjected to hot rolling without being reheated or after being reheated. When the slab is reheated, the reheating temperature is desirably about 1000 ° C. or higher, and it is necessary to set it to 1300 ° C. or lower. This is because slab heating above 1300 ° C is meaningless for the present invention, which contains almost no inhibitor in the steel at the slab stage, and only increases costs. On the other hand, when the slab is heated at a temperature lower than 1000 ° C., the rolling load at the time of hot rolling becomes high and it becomes difficult to perform rolling.
ついで、熱延板に、必要に応じて熱延板焼鈍を施したのち、１回の冷間圧延を施して、最終冷延板とする。この冷間圧延は、常温で行ってもよいし、常温より高い温度たとえば250℃程度に鋼板温度を上げて圧延する温間圧延としてもよい。
ここで、本発明では、上記冷間圧延の圧延条件について、前述したように、冷間圧延を250mm以上のワークロール径で行うことが必要である。
Next, the hot-rolled sheet is subjected to hot-rolled sheet annealing as necessary, and then cold-rolled once to obtain a final cold-rolled sheet. This cold rolling may be performed at normal temperature, or may be warm rolling in which the steel sheet temperature is raised to a temperature higher than normal temperature, for example, about 250 ° C.
Here, in the present invention, as described above, regarding the rolling conditions of the cold rolling, it is necessary to perform the cold rolling with a work roll diameter of 250 mm or more.
他方、冷間圧延の温度や圧延速度は、本発明の場合、大きな影響を及ぼさないと考えられる。また、タンデム圧延とゼンジミア圧延の差違については明瞭ではないが、前述の実験結果からは、本発明の最も大きな特徴である温間のパス間時効の効果があまり大きくないことから、ワークロール径の大きいタンデム圧延が有利となっている可能性がある。 On the other hand, it is considered that the temperature and the rolling speed of cold rolling do not have a great influence in the present invention. Moreover, although the difference between tandem rolling and Sendzimir rolling is not clear, from the above experimental results, the effect of warm interpass aging, which is the greatest feature of the present invention, is not so large, Large tandem rolling may be advantageous.
ここに、窒化珪素をインヒビターとする系に対するタンデム圧延に関連するパラメータのうち、圧延温度でなく、ワークロール径の違いが大きく影響した理由は定かではないが、ワークロール径の違いによって、鋼板のロールバイト内での変形が異なり、特に表面近傍に導入される剪断歪みの差違が生じたためではないかと推定している。すなわち、ワークロール径が大きいほど、鋼板は剪断変形を起こしにくく、単純圧縮に近づくからと考えられる。 Here, of the parameters related to tandem rolling for a system using silicon nitride as an inhibitor, it is not clear why the difference in work roll diameter, not the rolling temperature, was greatly affected. It is presumed that the deformation in the roll bite is different, especially because of the difference in shear strain introduced near the surface. That is, it is considered that as the work roll diameter is larger, the steel sheet is less likely to undergo shear deformation and approaches simple compression.
また、ワークロール径が、250mm以上の時、高い磁束密度が得られるのは、以下のように考えている。
すなわち、従来のスラブ高温加熱を必要とするMnSeやAlNインヒビターを利用する成分系ではインヒビターが鋼板内に均一分散しているのに対し、増窒処理により得られるSi3N4では、その析出およびインヒビション効果等が板厚方向に分布を持っていると考えられる。また、形成される圧延集合組織の板厚方向分布は、圧延変形挙動により異なっているはずである。
Further, the reason why a high magnetic flux density is obtained when the work roll diameter is 250 mm or more is considered as follows.
That is, in the conventional component system using MnSe or AlN inhibitor that requires high-temperature heating of the slab, the inhibitor is uniformly dispersed in the steel plate, whereas in Si 3 N 4 obtained by the nitrous treatment, the precipitation and It is considered that the inhibition effect has a distribution in the thickness direction. Further, the thickness direction distribution of the formed rolling texture should be different depending on the rolling deformation behavior.
ここで、Si3N4のインヒビション効果の発現と、導入される歪みおよび冷間圧延組織とに密接な関係があると仮定すれば、導入される歪み分布とその後形成される集合組織分布の組合せが、増窒処理により得られるSi3N4インヒビターのインヒビション効果と、そのインヒビション効果によって得られる二次再結晶挙動に大きな影響を与えていると考えられる。
なお、ワークロール径の上限値については、特に設けないが、圧延ミルの構造上タンデム圧延機においては800mm程度である。
Here, assuming that there is a close relationship between the expression of the inhibition effect of Si 3 N 4 and the strain to be introduced and the cold rolled structure, the strain distribution to be introduced and the texture distribution to be formed thereafter This combination is considered to have a great influence on the inhibition effect of the Si 3 N 4 inhibitor obtained by the nitriding treatment and the secondary recrystallization behavior obtained by the inhibition effect.
The upper limit of the work roll diameter is not particularly set, but is about 800 mm in a tandem rolling mill due to the structure of the rolling mill.
引き続き、最終板厚の冷間圧延板に一次再結晶焼鈍を施す。この一次再結晶焼鈍の目的は、圧延組織を有する冷間圧延板を一次再結晶させて、二次再結晶に最適な一次再結晶粒径に調整することである。そのためには、一次再結晶焼鈍の焼鈍温度を800℃以上950℃未満程度とすることが望ましい。なお、この時の焼鈍雰囲気を、湿水素窒素あるいは湿水素アルゴン雰囲気とし、脱炭焼鈍を兼ねても良い。 Subsequently, primary recrystallization annealing is performed on the cold-rolled sheet having the final thickness. The purpose of this primary recrystallization annealing is to adjust the primary recrystallization grain size optimal for secondary recrystallization by primary recrystallization of a cold rolled sheet having a rolled structure. For that purpose, it is desirable to set the annealing temperature of the primary recrystallization annealing to about 800 ° C. or more and less than 950 ° C. Note that the annealing atmosphere at this time may be wet hydrogen nitrogen or wet hydrogen argon atmosphere, and may also serve as decarburization annealing.
本発明における窒素増量のための窒化処理（増窒処理）は、一次再結晶焼鈍中、あるいは焼鈍後に施す。窒化の手法は、増量する窒化量を制御できれば、特に限定しないが、過去実施されている、例えば、コイル形態のままNH3雰囲気ガスを用いてガス窒化を行う手法や、走行するストリップに対して連続的に窒化を行う手法を採ることができる。また、ガス窒化に比べて窒化能の高い塩浴窒化を利用することも好ましい。 The nitriding treatment (nitrogen increasing treatment) for increasing the amount of nitrogen in the present invention is performed during the primary recrystallization annealing or after the annealing. The method of nitriding is not particularly limited as long as the amount of nitriding to be increased can be controlled. However, for example, a method of performing gas nitriding using an NH 3 atmosphere gas in a coil form or a running strip has been implemented in the past. A technique of nitriding continuously can be adopted. It is also preferable to use salt bath nitriding, which has a higher nitriding ability than gas nitriding.
上記窒化処理の際に重要な点は、表層に窒化物層を得ることである。特に鋼中への拡散を抑制するために800℃以下の温度で窒化を行なうことが望ましいが、時間を短時間（例えば30秒程度）とすることで高温であっても表面へ窒化物層を形成させることが可能となる。
また、窒化による窒素増量（△Ｎ）は50ppm以上1000ppm以下とするのが肝要である。窒素増量が50ppm未満では、その増窒効果は十分に得られず、一方、1000ppmを超えると窒化珪素の析出量が過多となって、効果的に二次再結晶が生じない。望ましくは200ppm以上1000ppm以下が好適範囲である。なお、当該窒素濃度は、例え鋼板の一部に濃化していたとしても、鋼板の厚み方向の平均に均した値である。
An important point in the nitriding process is to obtain a nitride layer as a surface layer. In order to suppress diffusion into steel, it is desirable to perform nitriding at a temperature of 800 ° C. or less. However, the nitride layer is formed on the surface even at high temperatures by shortening the time (for example, about 30 seconds). It can be formed.
It is important that the nitrogen increase (ΔN) by nitriding is 50 ppm or more and 1000 ppm or less. If the nitrogen increase is less than 50 ppm, the effect of increasing nitrogen cannot be obtained sufficiently. On the other hand, if it exceeds 1000 ppm, the amount of silicon nitride deposited becomes excessive and secondary recrystallization does not occur effectively. The preferred range is 200 ppm or more and 1000 ppm or less. Note that the nitrogen concentration is a value averaged to the average in the thickness direction of the steel plate even if it is concentrated in a part of the steel plate.
上記一次再結晶焼鈍および窒化処理を行った後、鋼板表面に焼鈍分離剤を塗布する。二次再結晶焼鈍後の鋼板表面にフォルステライト被膜を形成するためには、焼鈍分離剤の主剤をマグネシア（MgO）とする必要があるが、フォルステライト被膜の形成が必要ない場合には、焼鈍分離剤主剤として、アルミナ（Al203）やカルシア（CaO）など、二次再結晶焼鈍温度より高い融点を有する適当な酸化物を用いることができる。 After performing the primary recrystallization annealing and nitriding treatment, an annealing separator is applied to the steel sheet surface. In order to form a forsterite film on the steel sheet surface after secondary recrystallization annealing, it is necessary to use magnesia (MgO) as the main component of the annealing separator. As the separating agent main component, an appropriate oxide having a melting point higher than the secondary recrystallization annealing temperature, such as alumina (Al 2 O 3 ) or calcia (CaO), can be used.
二次再結晶焼鈍では、300〜800℃間の滞留時間を５時間以上150時間以下とすることが好ましい。窒化珪素の析出は、正常粒成長の抑制が目的であるため、正常粒成長が進行する800℃の段階では十分な量が粒界上に選択的に析出している必要があり、当該温度域の滞留時間を５時間以上とすることでは、粒内で析出することができない一方で、粒界を拡散して来たＮとSiとは、粒界上に選択的に析出することができるからである。一方、上限については必ずしも設ける必要はないが、150時間を超える焼鈍を行なっても焼鈍に要するエネルギーばかりが必要になるだけなので、150時間以下の時間で行なうことが望ましい。また焼鈍雰囲気は、Ｎ２、Ar、Ｈ２あるいはこれらの混合ガスのいずれもが適合する。 In the secondary recrystallization annealing, the residence time between 300 and 800 ° C. is preferably 5 hours or more and 150 hours or less. Since the purpose of precipitation of silicon nitride is to suppress normal grain growth, a sufficient amount must be selectively deposited on the grain boundary at the 800 ° C. stage where normal grain growth proceeds. When the retention time of 5 hours or more cannot be precipitated within the grains, N and Si diffused through the grain boundaries can be selectively deposited on the grain boundaries. It is. On the other hand, it is not always necessary to set an upper limit. However, even if annealing is performed for more than 150 hours, only the energy required for annealing is required. As the annealing atmosphere, any of N 2 , Ar, H 2 or a mixed gas thereof is suitable.
製造上、窒化珪素の析出には、二次再結晶昇温過程を利用するのがエネルギー効率の観点から、最も有効であることは明白であるが、同様のヒートサイクルを利用すれば窒化珪素の粒界選択析出は可能であるため、長時間の二次再結晶焼鈍の前に、窒化珪素分散焼鈍として、別途の熱処理を実施することも可能である。 From the viewpoint of energy efficiency, it is clear that the secondary recrystallization heating process is most effective for precipitation of silicon nitride in terms of production. However, if a similar heat cycle is used, Since grain boundary selective precipitation is possible, a separate heat treatment can be performed as silicon nitride dispersion annealing before the long-time secondary recrystallization annealing.
方向性電磁鋼板は、トランスなどの鉄心材料に用いられる場合、積層して使用されるため、層間絶縁のための絶縁層が必要である。追加で施される絶縁コートとしては、方向性電磁鋼板に、一般に使用される無機質コートが利用可能である。特に、張力付与効果を有するコーティングは、低鉄損化を達成するために鋼板表面を平滑化した方向性電磁鋼板との組合せが極めて有効である。
張力付与型コーティングの種類としては、熱膨張係数を低下させるシリカを含むコーティングが有効で、従来からフォルステライト被膜を有する方向性電磁鋼板に用いられているリン酸塩-コロイダルシリカ-クロム酸系のコーティング等が、その効果およびコスト、均一処理性などの点から好適である。なお、コーティングの厚みとしては、張力付与効果や占積率、被膜密着性等の点から0.3μm以上10μm以下の程度の範囲が好ましい。
When the grain-oriented electrical steel sheet is used for a core material such as a transformer, it is used by being laminated, so that an insulating layer for interlayer insulation is required. As the additionally applied insulating coating, a generally used inorganic coating can be used for the grain-oriented electrical steel sheet. In particular, a coating having a tension-imparting effect is extremely effective in combination with a grain-oriented electrical steel sheet in which the steel sheet surface is smoothed in order to achieve low iron loss.
As a type of tension-imparting coating, a coating containing silica that reduces the thermal expansion coefficient is effective, and the phosphate-colloidal silica-chromic acid system that has been used for grain-oriented electrical steel sheets having a forsterite film has been used. A coating or the like is preferable from the viewpoint of its effect and cost, uniform processability, and the like. The thickness of the coating is preferably in the range of about 0.3 μm or more and 10 μm or less from the viewpoint of tension application effect, space factor, film adhesion, and the like.
さらに、本発明では、平坦化焼鈍により、鋼板の形状を整えることが可能であり、この平坦化焼鈍を、絶縁被膜の焼付け処理と兼ねることもできる。
また、磁区細分化処理として、絶縁コート後にレーザや電子ビーム照射等の熱歪み導入型の磁区細分化処理を施すことでさらに低鉄損化をはかることが可能である。また機械的、電気化学的に物理的な溝を形成して磁区細分化を図り、鉄損を低減することも有効である。
Furthermore, in the present invention, the shape of the steel sheet can be adjusted by flattening annealing, and this flattening annealing can also serve as a baking treatment of the insulating coating.
Further, as the magnetic domain subdivision process, it is possible to further reduce the iron loss by applying a thermal strain introducing type magnetic domain subdivision process such as laser or electron beam irradiation after the insulating coating. It is also effective to reduce the iron loss by forming mechanical and electrochemical physical grooves to subdivide the magnetic domain.
表１に示される鋼記号１〜５の成分組成になるスラブを、1200℃に加熱後、熱間圧延し、2.2mm厚みの熱延コイルとした。次に、この熱延コイルを1000℃で焼鈍した後、酸洗し、ゼンジミア圧延機またはタンデム圧延機により0.23mm厚みに仕上げた。冷間圧延は、クーラント量の調整により50℃〜100℃の冷間条件と165℃〜220℃の温間条件とした。また、ワークロール径の影響についても併せて評価した。 The slab having the composition of steel symbols 1 to 5 shown in Table 1 was heated to 1200 ° C. and hot-rolled to obtain a hot-rolled coil having a thickness of 2.2 mm. Next, this hot rolled coil was annealed at 1000 ° C., pickled, and finished to a thickness of 0.23 mm by a Sendzimir mill or a tandem mill. The cold rolling was performed at a cold condition of 50 ° C to 100 ° C and a warm condition of 165 ° C to 220 ° C by adjusting the amount of coolant. Moreover, the influence of the work roll diameter was also evaluated.
各コイルを脱脂して850℃の湿水素雰囲気で脱炭焼鈍を行い、得られた脱炭焼鈍板より圧延方向に沿ってエプスタイン試料を冷間圧延条件ごとに切り出した。
ついで、アンモニアガス主体の窒化炉にて増窒処理をおこない、鋼中窒素量を増加させた。引続き、鋼板に、MgOを主体とする焼鈍分離剤を塗布後、1075℃までArとＮ２の混合雰囲気で加熱し、1200℃の純化焼鈍は、Ｈ２雰囲気で行った。その後、未反応分離剤を除去してから、コロイダルシリカとリン酸マグネシウムを主成分とする絶縁コーティングを800℃で形成した。さらに、加速電圧：60kVの電子銃を用いて圧延直角方向に５mm間隔で電子ビーム照射を行い、磁区細分化処理を施した。
かくして得られた製品の磁気特性評価として、1.7Ｔの磁束密度における50Hz交流励磁での鉄損値Ｗ17/50および磁束密度Ｂ８を測定した。表２に、上記圧延条件、Alの添加量、増窒量（ΔＮ）と得られた磁気特性をまとめた。
Each coil was degreased and decarburized and annealed in a wet hydrogen atmosphere at 850 ° C., and an Epstein sample was cut out for each cold rolling condition along the rolling direction from the obtained decarburized and annealed plate.
Next, nitrogen increase treatment was performed in a nitriding furnace mainly composed of ammonia gas to increase the amount of nitrogen in the steel. Subsequently, after applying an annealing separator mainly composed of MgO to the steel sheet, it was heated to 1075 ° C. in a mixed atmosphere of Ar and N 2 , and purification annealing at 1200 ° C. was performed in an H 2 atmosphere. Then, after removing the unreacted separating agent, an insulating coating composed mainly of colloidal silica and magnesium phosphate was formed at 800 ° C. Further, electron beam irradiation was performed at an interval of 5 mm in the direction perpendicular to the rolling direction using an electron gun with an acceleration voltage of 60 kV, and the magnetic domain was subdivided.
As an evaluation of the magnetic properties of the product thus obtained, the iron loss value W 17/50 and the magnetic flux density B 8 at 50 Hz AC excitation at a magnetic flux density of 1.7 T were measured. Table 2 summarizes the rolling conditions, the amount of Al added, the amount of nitrogen increase (ΔN), and the obtained magnetic properties.
表２から明らかなように、本発明条件を満たす条件Ａ、Ｅ、ＪおよびＬでは良好な磁気特性を示した。これに対して、Alの添加量が100ppmを超えた条件Ｂ、Ｄ、Ｇ、Ｉ、ＫおよびＮや、増窒量が不足あるいは過剰な条件Ｃ、Ｆ、ＨおよびＩ、ワークロール径が本発明範囲から外れた条件Ｆ、Ｇ、Ｍ、ＮおよびＯでは、いずれも良好な磁気特性が得られなかった。 As is apparent from Table 2, good magnetic properties were exhibited under the conditions A, E, J and L satisfying the present invention conditions. On the other hand, conditions B, D, G, I, K and N where the amount of Al added exceeds 100 ppm, conditions C, F, H and I where the amount of nitrogen increase is insufficient or excessive, and the work roll diameter are Under the conditions F, G, M, N, and O that are out of the scope of the invention, good magnetic properties were not obtained.
Claims (3)
上記冷間圧延時のワークロール径を320mm以上とし、
さらに、上記一次再結晶焼鈍中、焼鈍後のいずれかでかつ、上記二次再結晶焼鈍前のタイミングで、加熱温度：800℃以下、また、加熱温度：800℃超の場合には保持時間：30秒以下として、窒素増量（ΔＮ）が50質量ppm以上1000質量ppm以下となる窒化処理を施し、
また、上記二次再結晶焼鈍における300〜800℃間の滞留時間を５時間以上150時間以下とする、方向性電磁鋼板の製造方法。 In mass%, C: 0.08% or less, Si: 2.0 to 4.5% and Mn: 0.5% or less, S, Se and O are each less than 50 mass ppm, sol.Al is 100 mass ppm or less, and N is After the steel slab, which is controlled to 80 mass ppm or less and the balance is Fe and inevitable impurities, without reheating or after reheating, is hot-rolled at 1300 ° C or less and subjected to hot-rolled sheet annealing Alternatively, without performing hot-rolled sheet annealing, a cold-rolled sheet with the final thickness is obtained by a single cold rolling, and further, a primary recrystallization annealing is applied and an annealing separator is applied, and a secondary recrystallization annealing is performed. In the manufacturing process of a series of grain-oriented electrical steel sheets to be applied,
The diameter of the work roll at the time of the cold rolling is 320 mm or more,
Furthermore, during the primary recrystallization annealing, either after annealing , and at the timing before the secondary recrystallization annealing , the heating temperature: 800 ° C. or less, and the heating temperature: more than 800 ° C., the holding time: as less than 30 seconds, nitrogen increased (.DELTA.N) is facilities nitrided equal to or less than 50 mass ppm to 1000 ppm by weight,
Moreover, the manufacturing method of a grain- oriented electrical steel sheet which sets the residence time between 300-800 degreeC in the said secondary recrystallization annealing to 5 hours or more and 150 hours or less .
Ni：0.005〜1.50％、
Sn：0.01〜0.50％、
Sb：0.005〜0.50％、
Cu：0.01〜0.50％、
Cr：0.01〜1.50％、
Ｐ：0.0050〜0.50％、
Mo：0.01〜0.50％および
Nb：0.0005〜0.0100％
のうちから選んだ１種または２種以上を含有する請求項１または２に記載の方向性電磁鋼板の製造方法。 Furthermore, the said steel slab is mass%,
Ni: 0.005-1.50%,
Sn: 0.01 to 0.50%,
Sb: 0.005-0.50%,
Cu: 0.01 to 0.50%,
Cr: 0.01 to 1.50%,
P: 0.0050 to 0.50%,
Mo: 0.01-0.50% and
Nb: 0.0005-0.0100%
The manufacturing method of the grain-oriented electrical steel sheet according to claim 1 or 2, comprising one or more selected from among the above.
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