JP2014173098A - Method of producing grain-oriented magnetic steel sheet - Google Patents
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Abstract
Description
本発明は、方向性電磁鋼板の製造方法に関し、具体的には、低鉄損でかつ鉄損値のばらつきが小さい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 manufacturing a grain-oriented electrical steel sheet, and specifically relates to a method for producing a grain-oriented electrical steel sheet with low iron loss and small variations in iron loss values.
電磁鋼板は、変圧器やモータの鉄心材料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ため、主として大型の変圧器の鉄心等に使用されている。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、鉄損が低いことが必要である。 Electrical steel sheets are soft magnetic materials that are widely used as core materials for transformers and motors. Among them, grain oriented electrical steel sheets are highly integrated in the {110} <001> orientation, which is called the Goss orientation. Because of its excellent magnetic properties, it is mainly used for iron cores of large transformers. In order to reduce the no-load loss (energy loss) in the transformer, it is necessary that the iron loss is low.
方向性電磁鋼板における鉄損低減方法としては、Ｓｉ含有量の増加や、板厚の低減、結晶方位の配向性向上、鋼板表面への張力付与、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。 Iron loss reduction method for grain-oriented electrical steel sheets includes increasing Si content, reducing plate thickness, improving crystal orientation orientation, imparting tension to the steel sheet surface, smoothing the steel sheet surface, secondary recrystallization texture It is known that fine graining is effective.
これらの方法のうち、二次再結晶粒を細粒化する技術としては、脱炭焼鈍時に急速加熱したり、脱炭焼鈍直前に急速加熱する熱処理を施したりすることで、一次再結晶集合組織を改善する方法が提案されている。例えば、特許文献１には、最終板厚まで圧延した冷延板を脱炭焼鈍する際、ＰＨ２Ｏ／ＰＨ２が０．２以下の非酸化性雰囲気中で、１００℃／ｓ以上で７００℃以上の温度に急速加熱することで、低鉄損の方向性電磁鋼板を得る技術が開示されている。また、特許文献２には、雰囲気中の酸素濃度を５００ｐｐｍ以下とし、かつ、加熱速度１００℃／ｓ以上で８００〜９５０℃に急速加熱し、続いて急速加熱後の温度より低い７７５〜８４０℃の温度に保定し、さらに、８１５〜８７５℃の温度に保定することで、低鉄損の方向性電磁鋼板を得る技術が開示されている。また、特許文献３には、６００℃以上の温度域を９５℃／ｓ以上の昇温速度で８００℃以上に加熱し、かつ、この温度域の雰囲気を適正に制御することによって、被膜特性と磁気特性に優れる電磁鋼板を得る技術が開示されている。さらに、特許文献４には、熱延板中のＡｌＮとしてのＮ量を２５ｐｐｍ以下に制限し、かつ脱炭焼鈍時に加熱速度８０℃／ｓ以上で７００℃以上まで加熱することで、低鉄損の方向性電磁鋼板を得る技術が開示されている。
Among these methods, the technology for refining secondary recrystallized grains includes rapid heating at the time of decarburization annealing, or heat treatment to be rapidly heated immediately before decarburization annealing, thereby providing a primary recrystallization texture. A method for improving the above has been proposed. For example, in
急速加熱することで一次再結晶集合組織を改善するこれらの技術は、急速加熱する温度範囲を室温から７００℃以上とし、昇温速度を一義的に規定するものである。この技術思想は、再結晶温度近傍までを短時間で昇温することで、通常の加熱速度であれば優先的に形成されるγファイバー（＜１１１＞／／ＮＤ方位）の発達を抑制し、二次再結晶の核となる｛１１０｝＜００１＞組織の発生を促進することで、一次再結晶集合組織を改善しようとするものである。そして、この技術の適用により、二次再結晶後の結晶粒（Ｇｏｓｓ方位粒）が細粒化し、鉄損特性が改善される。 In these techniques for improving the primary recrystallization texture by rapid heating, the temperature range for rapid heating is from room temperature to 700 ° C. or higher, and the rate of temperature rise is uniquely defined. This technical idea suppresses the development of γ fibers (<111> // ND orientation) that are preferentially formed at a normal heating rate by raising the temperature to near the recrystallization temperature in a short time, The primary recrystallization texture is intended to be improved by promoting the generation of a {110} <001> structure that becomes the nucleus of secondary recrystallization. By applying this technique, the crystal grains (Goss-oriented grains) after the secondary recrystallization are refined, and the iron loss characteristics are improved.
しかしながら、発明者らの知見によれば、一次再結晶焼鈍（または脱炭焼鈍を伴う一次再結晶焼鈍）の加熱過程における昇温速度を高くした場合には、昇温時の鋼板内部の温度ムラに起因すると思われる鉄損特性のばらつきが大きくなるという問題がある。特に、製造工程の途中で窒化処理を施す製造方法の場合には、そのばらつきが顕著となる。製品出荷時の鉄損評価には、一般に、鋼板の全幅の鉄損を平均した値が用いられているため、ばらつきが大きいと、鋼板全体の鉄損が低く評価されることとなり、所期した急速加熱の効果が得られなくなる。 However, according to the knowledge of the inventors, when the rate of temperature increase in the heating process of primary recrystallization annealing (or primary recrystallization annealing accompanied by decarburization annealing) is increased, temperature unevenness inside the steel sheet during temperature increase There is a problem that the variation of the iron loss characteristic which is considered to be caused by this becomes large. In particular, in the case of a manufacturing method in which nitriding is performed during the manufacturing process, the variation becomes significant. The iron loss evaluation at the time of product shipment generally uses the average value of the iron loss of the full width of the steel sheet. Therefore, if the variation is large, the iron loss of the entire steel sheet will be evaluated low, which is expected. The effect of rapid heating cannot be obtained.
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、従来技術に比べて低鉄損でかつ鉄損値のばらつきが小さい方向性電磁鋼板の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-mentioned problems of the prior art, and its purpose is to propose a method for producing a grain-oriented electrical steel sheet having a low iron loss and a small variation in iron loss values compared to the prior art. There is to do.
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、一次再結晶焼鈍において急速加熱する際、回復が起こる温度領域で所定時間保持する保定処理を施すことで、鋼板内部の温度が均一化され、前述した急速加熱の効果を鋼板の全幅にわたって得ることができるとともに、一次粒径の大きさの均一化も達成され、さらに、＜１１１＞／／ＮＤ方位が優先的に回復を起こして一次再結晶後の＜１１１＞／／ＮＤ方位が減少し、代わりにＧｏｓｓ核が増加し、二次再結晶後の結晶粒がより細粒化される結果、低鉄損でかつ鉄損値のばらつきが小さい方向性電磁鋼板を得ることができることを見出し、本発明を開発するに至った。 The inventors have intensively studied to solve the above problems. As a result, when rapid heating is performed in the primary recrystallization annealing, the temperature inside the steel plate is made uniform by applying a holding treatment that is held for a predetermined time in a temperature range where recovery occurs, and the effect of the rapid heating described above over the entire width of the steel plate. In addition, the primary particle size can be made uniform, and the <111> // ND orientation is preferentially recovered to reduce the <111> // ND orientation after the primary recrystallization. However, instead of increasing Goss nuclei and making the crystal grains after secondary recrystallization finer, it was found that a grain-oriented electrical steel sheet with low iron loss and small variation in iron loss values can be obtained. The present invention has been developed.
すなわち本発明は、Ｃ：０．００２〜０．１０ｍａｓｓ％、Ｓｉ：２．０〜８．０ｍａｓｓ％、Ｍｎ：０．００５〜１．０ｍａｓｓ％、Ａｌ：０．０１ｍａｓｓ％未満、Ｎ：０．００５０ｍａｓｓ％未満、Ｓｅ：０．００３０ｍａｓｓ％未満およびＳ：０．００５０ｍａｓｓ％未満を含有し、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、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、一次再結晶焼鈍を施し、かつ、一次再結晶焼鈍の途中あるいは一次再結晶焼鈍後に窒化処理を施した後、鋼板表面に焼鈍分離剤を塗布し、仕上焼鈍する方向性電磁鋼板の製造方法において、前記一次再結晶焼鈍の加熱過程における２００〜７００℃間を５０℃／ｓ以上で急速加熱し、かつ、２５０〜６００℃間のいずれかの温度で１〜１０秒間保持する保定処理を施すとともに、続く７００〜８００℃間の領域における滞留時間を５秒以上とすることによって、一次再結晶焼鈍後の一次粒径の鋼板板幅方向のばらつきを１０％以内とすることを特徴とする方向性電磁鋼板の製造方法である。 That is, the present invention is C: 0.002-0.10 mass%, Si: 2.0-8.0 mass%, Mn: 0.005-1.0 mass%, Al: less than 0.01 mass%, N: 0.00. A steel material containing less than 0050 mass%, Se: less than 0.0030 mass% and S: less than 0.0050 mass%, with the balance being Fe and inevitable impurities, is hot-rolled into a hot-rolled sheet once or intermediate annealing The steel plate surface is subjected to cold rolling at least twice to sandwich a cold rolled sheet with a final thickness, subjected to primary recrystallization annealing, and subjected to nitriding during or after primary recrystallization annealing. In the manufacturing method of the grain-oriented electrical steel sheet, which is applied with an annealing separator and finish-annealed, 200 to 700 ° C. in the heating process of the primary recrystallization annealing is rapidly heated at 50 ° C./s or more and 250 The primary particle size after the primary recrystallization annealing is performed by applying a holding treatment for holding at any temperature between 600 ° C. for 1 to 10 seconds and setting the residence time in the subsequent region between 700 to 800 ° C. to 5 seconds or more. This is a method for producing a grain-oriented electrical steel sheet characterized in that the variation in the width direction of the steel sheet is within 10%.
本発明の方向性電磁鋼板の製造方法は、上記窒化処理における鋼板中の増窒量を０．００５０〜０．１０００ｍａｓｓ％の範囲とすることを特徴とする。 The grain-oriented electrical steel sheet manufacturing method of the present invention is characterized in that the amount of nitriding in the steel sheet in the nitriding treatment is in the range of 0.0050 to 0.1000 mass%.
また、本発明の方向性電磁鋼板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：０．０１０〜１．５０ｍａｓｓ％、Ｃｒ：０．０１〜０．５０ｍａｓｓ％、Ｃｕ：０．０１〜０．５０ｍａｓｓ％、Ｐ：０．００５〜０．５０ｍａｓｓ％、Ｓｂ：０．００５〜０．５０ｍａｓｓ％、Ｓｎ：０．００５〜０．５０ｍａｓｓ％、Ｂｉ：０．００５〜０．５０ｍａｓｓ％、Ｍｏ：０．００５〜０．１００ｍａｓｓ％、Ｔｅ：０．０００５〜０．０１００ｍａｓｓ％およびＮｂ：０．００１０〜０．０１００ｍａｓｓ％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。 Moreover, in addition to the said component composition, the said steel raw material used for the manufacturing method of the grain-oriented electrical steel sheet of this invention is further Ni: 0.010-1.50 mass%, Cr: 0.01-0.50 mass%, Cu : 0.01 to 0.50 mass%, P: 0.005 to 0.50 mass%, Sb: 0.005 to 0.50 mass%, Sn: 0.005 to 0.50 mass%, Bi: 0.005 to 0 .50 mass%, Mo: 0.005 to 0.100 mass%, Te: 0.0005 to 0.0100 mass%, and Nb: 0.0010 to 0.0100 mass%, one or more selected from It is characterized by that.
本発明によれば、一次再結晶焼鈍において急速加熱する際、回復が起こる温度領域で所定時間保定してやる保定処理を施すことで、急速加熱の効果を鋼板の全幅にわたって得ることができるだけでなく、一次再結晶焼鈍後の一次粒径のばらつきが低減されるので、低鉄損でかつ鉄損値のばらつきが小さい方向性電磁鋼板を安定して得ることが可能となる。 According to the present invention, when rapid heating is performed in the primary recrystallization annealing, the effect of rapid heating can be obtained over the entire width of the steel sheet by performing a retaining treatment that is retained for a predetermined time in a temperature range where recovery occurs, Since the variation in the primary particle size after the recrystallization annealing is reduced, it becomes possible to stably obtain a grain-oriented electrical steel sheet having a low iron loss and a small variation in the iron loss value.
まず、本発明を開発する契機となった実験について説明する。
＜実験１＞
Ｃ：０．０４３ｍａｓｓ％、Ｓｉ：３．２２ｍａｓｓ％、Ｍｎ：０．１０ｍａｓｓ％、Ａｌ：０．００８ｍａｓｓ％、Ｎ：０．００４２ｍａｓｓ％、Ｓｅ：０．００１ｍａｓｓ％およびＳ：０．００２２ｍａｓｓ％を含有する鋼を溶製し、連続鋳造法で鋼スラブとした後、１２３０℃に再加熱し、熱間圧延して板厚２．４ｍｍの熱延板とし、１０２５℃×６０秒の熱延板焼鈍を施した後、冷間圧延して最終板厚０．２７ｍｍの冷延板とした。
First, an experiment that triggered the development of the present invention will be described.
<
C: 0.043 mass%, Si: 3.22 mass%, Mn: 0.10 mass%, Al: 0.008 mass%, N: 0.0042 mass%, Se: 0.001 mass%, and S: 0.0022 mass% The steel to be melted and made into a steel slab by the continuous casting method, reheated to 1230 ° C, hot-rolled into a hot-rolled sheet with a thickness of 2.4 mm, and hot-rolled sheet annealed at 1025 ° C x 60 seconds Then, cold rolling was performed to obtain a cold-rolled sheet having a final thickness of 0.27 mm.
次いで、上記冷延板を、５０ｖｏｌ％Ｈ２−５０ｖｏｌ％Ｎ２の湿潤雰囲気下で８４０℃×８０秒の脱炭焼鈍を伴う一次再結晶焼鈍を施した。なお、上記一次再結晶焼鈍は、８４０℃までの加熱過程における２００〜７００℃間の昇温速度を１００℃／ｓとし、さらにその加熱途中の４５０℃の温度で０〜３０秒間保持する保定処理を施した。ここで、上記１００℃／ｓの昇温速度は、図１に示したように、２００℃から７００℃まで到達する時間から保定時間ｔ２を除いたｔ１およびｔ３における平均昇温速度（（７００−２００）／（ｔ１＋ｔ３））のことをいう（以降、同様）。また、上記加熱過程における７００〜８００℃間の滞留時間は８秒とした。その後、８４０℃まで加熱・均熱した後、アンモニア雰囲気下で８００℃×２０秒の窒化処理を施した。この窒化処理後の鋼板中の窒素量は０．０４２５〜０．０４９９ｍａｓｓ％であり、増窒量は０．０３８３〜０．０４５７ｍａｓｓ％であった。
その後、鋼板表面にＭｇＯを主体とする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１２２０℃×１０時間の純化処理を含む仕上焼鈍を施し、製品板とした。
Next, the cold-rolled sheet was subjected to primary recrystallization annealing with decarburization annealing at 840 ° C. for 80 seconds in a wet atmosphere of 50 vol% H 2 -50 vol% N 2 . The primary recrystallization annealing is a holding treatment in which the temperature rising rate between 200 to 700 ° C. in the heating process up to 840 ° C. is set to 100 ° C./s, and further maintained at 450 ° C. during the heating for 0 to 30 seconds. Was given. Here, as shown in FIG. 1, the temperature increase rate of 100 ° C./s is the average temperature increase rate at t 1 and t 3 excluding the holding time t 2 from the time to reach from 200 ° C. to 700 ° C. (700-200) / (t 1 + t 3 )) (hereinafter the same). Moreover, the residence time between 700-800 degreeC in the said heating process was 8 second. Then, after heating and soaking to 840 ° C., nitriding treatment was performed at 800 ° C. for 20 seconds in an ammonia atmosphere. The amount of nitrogen in the steel sheet after the nitriding treatment was 0.0425 to 0.0499 mass%, and the amount of nitrogen increase was 0.0383 to 0.0457 mass%.
Thereafter, an annealing separator mainly composed of MgO was applied to the steel sheet surface, and after drying, a secondary recrystallization annealing and a finish annealing including purification at 1220 ° C. for 10 hours under a hydrogen atmosphere were performed to obtain a product plate. .
斯くして得た製品板から、鋼板板幅方向に幅１００ｍｍ×長さ５００ｍｍの試験片を各条件で１０枚ずつ採取し、ＪＩＳ Ｃ２５５６に記載の方法で鉄損Ｗ１７／５０を測定し、それらの平均値を求めた。この鉄損測定方法によれば、鉄損のばらつきが板幅方向にある場合には測定値が悪化するので、ばらつきを含めて鉄損を評価できると考えられるからである。その結果を、図２に、４５０℃の保定処理における保定時間と鉄損Ｗ１７／５０との関係として示した。この図から、保定時間が１〜１０秒の範囲で鉄損が低減していることがわかる。 From the product plate thus obtained, 10 test pieces each having a width of 100 mm and a length of 500 mm in the width direction of the steel plate were collected under each condition, and the iron loss W 17/50 was measured by the method described in JIS C2556. Their average value was determined. This is because, according to this iron loss measurement method, when the variation in the iron loss is in the sheet width direction, the measured value is deteriorated, so it is considered that the iron loss can be evaluated including the variation. The results are shown in FIG. 2 as the relationship between the holding time and the iron loss W 17/50 in the 450 ° C. holding treatment. From this figure, it can be seen that the iron loss is reduced in the range of the holding time of 1 to 10 seconds.
＜実験２＞
実験１で得られた最終板厚０．２７ｍｍの冷延板に、５０ｖｏｌ％Ｈ２−５０ｖｏｌ％Ｎ２の湿潤雰囲気下で、８４０℃×８０秒の脱炭焼鈍を伴う一次再結晶焼鈍を施した。なお、上記一次再結晶焼鈍における２００〜７００℃間の昇温速度は１００℃／ｓとし、その加熱過程の２００〜７００℃間の任意の温度で１回、３秒間保持する保定処理を施した。また、その後の加熱過程における７００〜８００℃問の滞留時間は８秒とした。
次いで、上記一次再結晶焼鈍後の鋼板に、アンモニア雰囲気下で、８００℃×２０秒の窒化処理を施した。なお、この窒化処理による鋼板中の増窒量は０．０４１０〜０．０４６５ｍａｓｓ％であった。
その後、鋼板表面にＭｇＯを主体とする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１２２０℃×１０時間の純化処理を含む仕上焼鈍を施し、製品板とした。
<Experiment 2>
The cold rolled sheet having a final thickness of 0.27 mm obtained in
Next, the steel sheet after the primary recrystallization annealing was subjected to nitriding treatment at 800 ° C. for 20 seconds in an ammonia atmosphere. The amount of increase in nitrogen in the steel sheet by this nitriding treatment was 0.0410 to 0.0465 mass%.
Thereafter, an annealing separator mainly composed of MgO was applied to the steel sheet surface, and after drying, a secondary recrystallization annealing and a finish annealing including purification at 1220 ° C. for 10 hours under a hydrogen atmosphere were performed to obtain a product plate. .
斯くして得た製品板から、鋼板板幅方向に幅１００ｍｍ×長さ５００ｍｍの試験片を各条件で１０枚ずつ採取し、ＪＩＳ Ｃ２５５６に記載の方法で鉄損Ｗ１７／５０を測定し、それらの平均値を求めた。その結果を、図３に、保定処理における保定温度と鉄損Ｗ１７／５０との関係を示した。この図から、保定温度が２５０〜６００℃の間で、鉄損が低減していることがわかる。 From the product plate thus obtained, 10 test pieces each having a width of 100 mm and a length of 500 mm in the width direction of the steel plate were collected under each condition, and the iron loss W 17/50 was measured by the method described in JIS C2556. Their average value was determined. FIG. 3 shows the relationship between the holding temperature and the iron loss W 17/50 in the holding process. From this figure, it can be seen that the iron loss is reduced when the holding temperature is 250 to 600 ° C.
また、一次再結晶焼鈍後の鋼板からサンプルを採取し、板端部５０ｍｍから板幅方向の１００ｍｍおきに一次再結晶後の結晶粒径（以降、「一次粒径」ともいう）を測定し、板幅方向における一次粒径のばらつきの大きさを調査した。なお、上記冷延板の板幅は１２００ｍｍであるので、板幅方向の測定箇所は１２箇所となる。
Further, a sample is taken from the steel sheet after the primary recrystallization annealing, and the crystal grain size after the primary recrystallization (hereinafter, also referred to as “primary grain size”) is measured every 100 mm in the plate width direction from the
ここで、上記一次粒径の測定は、板幅方向の板厚断面を５ｖｏｌ％ナイタール液でエッチングして粒界を現出させ、１箇所につき板厚０．２７ｍｍ×板幅方向１０ｍｍの範囲を画像処理して平均円相当径を求め、１２箇所の平均値を算出した。
また、一次粒径のばらつきの大きさは、上記１２箇所の一次粒径の標準偏差σを求め、その値を一次粒径の平均値で除し、さらに１００を掛けた値（％）とした。
その結果を図４に示す。この図から、図３において鉄損が低減している保定温度範囲では、一次粒径のばらつきも小さくなっていること、すなわち、一次粒径のばらつきを低減することにより、鉄損特性が改善されることがわかる。
Here, the primary particle size is measured by etching the plate thickness section in the plate width direction with 5 vol% nital solution to reveal the grain boundary, and the range of plate thickness 0.27 mm ×
Further, the variation in the primary particle size was obtained by calculating the standard deviation σ of the primary particle size at the 12 locations, dividing the value by the average value of the primary particle size, and further multiplying by 100 (%). .
The result is shown in FIG. From this figure, in the holding temperature range where the iron loss is reduced in FIG. 3, the variation in the primary particle size is also reduced, that is, the variation in the primary particle size is reduced, thereby improving the iron loss characteristic. I understand that
＜実験３＞
実験１で得られた最終板厚０．２７ｍｍの冷延板に、５０ｖｏｌ％Ｈ２−５０ｖｏｌ％Ｎ２の湿潤雰囲気下で、８４０℃×８０秒の脱炭焼鈍を伴う一次再結晶焼鈍を施した。なお、上記一次再結晶焼鈍の８４０℃までの加熱過程における２００〜７００℃間の昇温速度は１００℃／ｓとし、その昇温途中の５００℃の温度で１秒間保持する保定処理を施した。その後の加熱過程においては、７００〜８００℃間の滞留時間を種々変更して８４０℃まで加熱・均熱した後、アンモニア雰囲気下で、８００℃×２０秒の窒化処理を施した。なお、この窒化処理による鋼板中の増窒量は０．０３３３〜０．０３７７ｍａｓｓ％であった。
その後、窒化処理後の鋼板表面にＭｇＯを主体とする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℃×５時間の純化処理を含む仕上焼鈍を施し、製品板とした。
<
The cold rolled sheet having a final thickness of 0.27 mm obtained in
Then, after applying an annealing separator mainly composed of MgO on the steel sheet surface after nitriding treatment and drying, a secondary recrystallization annealing and finishing annealing including a purification treatment at 1200 ° C. for 5 hours in a hydrogen atmosphere are performed, A product plate was used.
斯くして得た製品板から、鋼板の板幅方向に幅１００ｍｍ×長さ５００ｍｍの試験片を各条件で１０枚ずつ採取し、ＪＩＳ Ｃ２５５６に記載の方法で鉄損Ｗ１７／５０を測定し、それらの平均値を求めた。その結果を、図５に、７００〜８００℃間の滞留時間Ｗ１７／５０と鉄損との関係として示した。この図から、７００〜８００℃間の滞留時間を５〜３５秒の範囲とすることで鉄損を低減できることがわかる。 Ten test pieces each having a width of 100 mm and a length of 500 mm in the width direction of the steel plate were collected from the product plate thus obtained under each condition, and the iron loss W 17/50 was measured by the method described in JIS C2556. The average value of them was obtained. The results are shown in FIG. 5 as the relationship between the residence time W 17/50 between 700 and 800 ° C. and the iron loss. From this figure, it can be seen that the iron loss can be reduced by setting the residence time between 700 and 800 ° C. in the range of 5 to 35 seconds.
上記＜実験１＞〜＜実験３＞の結果のように、一次再結晶焼鈍の昇温過程の適正温度で適正時間保持する保定処理を施すことによって鉄損が改善される理由については、まだ十分明らかとなっていないが、発明者らは次のように考えている。
急速加熱処理は、前述したように、再結晶集合組織における＜１１１＞／／ＮＤ方位の発達を抑制し、二次再結晶の核となるＧｏｓｓ方位粒（｛１１０｝＜００１＞）の発生を促進する効果がある。一般に、冷間圧延では、＜１１１＞／／ＮＤ方位は、他の方位に比較して多くの歪が導入されるため、蓄積される歪エネルギーが高い状態にある。そのため、通常の昇温速度で加熱する一次再結晶焼鈍では、蓄積された歪エネルギーが高い＜１１１＞／／ＮＤ方位の圧延組織から優先的に再結晶を起こす。再結晶では、通常、＜１１１＞／／ＮＤ方位の圧延組織からは＜１１１＞／／ＮＤ方位粒が出現するため、再結晶後の組織は＜１１１＞／／ＮＤ方位が主方位となる。
As for the results of the above <
As described above, the rapid heat treatment suppresses the development of the <111> // ND orientation in the recrystallization texture, and the generation of Goss orientation grains ({110} <001>) serving as the nucleus of secondary recrystallization. There is an effect to promote. In general, in cold rolling, the <111> // ND orientation is in a state where the accumulated strain energy is high because more strain is introduced compared to other orientations. For this reason, in primary recrystallization annealing in which heating is performed at a normal temperature increase rate, recrystallization occurs preferentially from a <111> // ND-oriented rolling structure in which accumulated strain energy is high. In recrystallization, since grains with <111> // ND orientation usually appear from a rolled structure with <111> // ND orientation, the structure after recrystallization has the <111> // ND orientation as the main orientation.
しかし、急速加熱を行うと、再結晶によって放出されるエネルギーよりも多くの熱エネルギーが付与されることから、比較的蓄積された歪エネルギーの低いＧｏｓｓ方位でも再結晶が起こるようになり、相対的に再結晶後の＜１１１＞／／ＮＤ方位が減少し、Ｇｏｓｓ方位（｛１１０｝＜００１＞）が増加する。Ｇｏｓｓ方位が多くなると、二次再結晶においても多くのＧｏｓｓ方位粒が出現するため、二次再結晶粒が細粒化し、鉄損が低減する。これが、従来技術における急速加熱を行う理由である。 However, since rapid heating gives more thermal energy than that released by recrystallization, recrystallization occurs even in the Goss orientation with a relatively low strain energy. <111> // ND orientation after recrystallization decreases, and Goss orientation ({110} <001>) increases. When the Goss orientation increases, many Goss orientation grains appear in the secondary recrystallization, so the secondary recrystallization grains become finer and the iron loss is reduced. This is the reason for the rapid heating in the prior art.
ここで、急速加熱の途中で、回復が起こる温度に所定時間保持する保定処理を施した場合には、歪エネルギーが高い＜１１１＞／／ＮＤ方位が優先的に回復を起こす。そのため、＜１１１＞／／ＮＤ方位の圧延組織から生じる＜１１１＞／／ＮＤ方位の再結晶を起こす駆動力が選択的に低下し、それ以外の方位が再結晶を起こすようになる。その結果、再結晶後の＜１１１＞／／ＮＤ方位が相対的にさらに減少する。ただし、保定温度が高過ぎたり、保定時間が１０秒を超えたりすると、広い範囲で回復が起こってしまうため、回復組織がそのまま残り、上記の一次再結晶組織とは異なる組織となってしまう。その結果、二次再結晶に大きな悪影響を与え、鉄損特性が劣化してしまう。 Here, in the middle of rapid heating, when a retention treatment is performed to maintain the temperature at which recovery occurs for a predetermined time, the <111> // ND orientation with high strain energy recovers preferentially. Therefore, the driving force causing recrystallization of <111> // ND orientation generated from the rolled structure of <111> // ND orientation is selectively reduced, and other orientations cause recrystallization. As a result, the <111> // ND orientation after recrystallization is relatively further reduced. However, if the retention temperature is too high or the retention time exceeds 10 seconds, recovery occurs over a wide range, so that the recovery structure remains as it is, and the structure is different from the primary recrystallization structure. As a result, the secondary recrystallization is greatly adversely affected and the iron loss characteristics are deteriorated.
なお、上記考えによれば、加熱途中の回復が起こる温度で短時間の保定処理を施すことによる磁気特性向上効果が得られるのは、従来のラジアントチューブ等を用いた昇温速度（１０〜２０℃／ｓ）よりも速い昇温速度、具体的には５０℃／ｓ以上の昇温速度の場合に限られると考えられる。そこで、本発明においては、一次再結晶焼鈍の２００〜７００℃の温度範囲における昇温速度を５０℃／ｓ以上と規定する。 In addition, according to the said idea, the magnetic property improvement effect by performing a short-time holding | maintenance process at the temperature where recovery | restoration in the middle of a heating is acquired is the temperature increase rate (10-20) using the conventional radiant tube etc. It is considered that the rate of temperature increase is higher than (° C./s), specifically, a rate of temperature increase of 50 ° C./s or more. Therefore, in the present invention, the rate of temperature rise in the temperature range of 200 to 700 ° C. for primary recrystallization annealing is defined as 50 ° C./s or more.
また、上記加熱途中の保定処理は、上述した組織変化のみならず、一次粒径のばらつきを抑制する効果がある。というのは、＜１１１＞／／ＮＤ方位を有する圧延組織は優先的に再結晶を起こすが、その再結晶粒は優先的に成長して粗大化するため、他の方位粒とは一次粒径が異なることになり、整粒組織が得られないからである。しかし、保定処理を施すことによって、＜１１１＞／／ＮＤ方位の再結晶が抑制されるため、一次粒径が均一化される。 In addition, the holding treatment during heating has an effect of suppressing not only the above-described change in structure but also the variation in primary particle size. This is because a rolled structure having <111> // ND orientation preferentially recrystallizes, but the recrystallized grains grow preferentially and become coarser. This is because the sized structure cannot be obtained. However, by performing the retention treatment, recrystallization in the <111> // ND orientation is suppressed, so that the primary particle size is made uniform.
さらに、一次再結晶焼鈍の加熱過程において、上記急速加熱後の７００〜８００℃間の滞留時間を５秒以上とした場合には、＜１１１＞／／ＮＤ方位の粒成長が抑えられることによって、一次粒径をより均一化する効果がある。というのは、７００℃の時点では、ほぼ再結晶が完了し、以後、粒成長が進行することとなるが、この時、最も多くかつ大きい再結晶粒は、＜１１１＞／／ＮＤ方位粒であり、隣り合う粒の方位も＜１１１＞／／ＮＤ方位が多いことになる。＜１１１＞／／ＮＤ方位粒の主たる方位は｛１１１｝＜１１２＞方位であるが、この方位のバリアントは２種類存在し、この方位が隣り合った場合には、同じ方位同士となり、方位差角が０°となるか、異なるバリアントが隣り合い、方位差角が６０°になるかのどちらかとなる。これらの方位差角は、低傾角粒界、Σ３対応粒界であり、粒界エネルギーが低く、動きにくい粒界である。ここで、７００〜８００℃間の滞在時間を５秒以上とする加熱を行うと、一気に高温均熱温度まで加熱する場合と比較して与える熱エネルギーの供給が緩やかとなる。与える熱エネルギーの供給が緩やかになると、動き難い｛１１１｝＜１１２＞方位同士の粒界が動くよりも、その他の粒界が動くことにエネルギーが消費されると考えられる。そうすると、相対的に｛１１１｝＜１１２＞方位粒の粒成長が遅くなり、その他の粒の粒成長が速くなると考えられる。上述の通り、７００℃の時点では、＜１１１＞／／ＮＤ方位粒の粒径が大きいと推測されるため、その後の粒成長を上記のように制御することで、さらに全体的な粒径の均一化が図られると考えられる。 Furthermore, in the heating process of the primary recrystallization annealing, when the residence time between 700 to 800 ° C. after the rapid heating is set to 5 seconds or more, the grain growth of <111> // ND orientation is suppressed, There is an effect of making the primary particle size more uniform. This is because at 700 ° C., recrystallization is almost completed, and thereafter grain growth proceeds. At this time, the largest and largest recrystallized grains are <111> // ND oriented grains. There are many <111> // ND orientations of adjacent grains. The main orientation of the <111> // ND orientation grain is the {111} <112> orientation, but there are two kinds of orientation variants. Either the angle is 0 ° or different variants are next to each other and the heading difference angle is 60 °. These misorientation angles are low-angle grain boundaries and Σ3-compatible grain boundaries, which are low grain boundary energy and difficult to move. Here, when heating is performed so that the staying time between 700 and 800 ° C. is 5 seconds or more, the supply of thermal energy to be given is moderate as compared with the case of heating to a high temperature soaking temperature all at once. If the supplied thermal energy is moderated, it is considered that energy is consumed by movement of other grain boundaries rather than movement of grain boundaries of {111} <112> orientations which are difficult to move. Then, it is considered that the grain growth of {111} <112> oriented grains is relatively slow, and the grain growth of other grains is accelerated. As described above, since the particle size of <111> // ND-oriented grains is estimated to be large at 700 ° C., by controlling the subsequent grain growth as described above, the overall grain size is further increased. It is thought that uniformization is achieved.
さらに、このような一次粒径の均一化効果は、インヒビター成分を含まない鋼素材を用いる方向性電磁鋼板の製造方法において窒化処理を施す場合には、板幅方向の磁気特性のばらつきを抑える効果を有する。発明者らは、インヒビター成分を含有しない鋼板に窒化処理を施した場合には、窒化処理により、鋼中に窒素が拡散し、その過程で粒界にＳｉ３Ｎ４の析出物が形成されることを事前実験により確認している。一次粒径が不均一であると、その粒界に形成されるＳｉ３Ｎ４もマクロ的にみると不均一な分布となる。つまり、マクロ的に見ると、細かい一次粒径の粒界には析出物が密に分布し、一方、粗大な一次粒径の粒径には析出物は疎に分布するため、二次再結晶に及ぼす析出物の効果が不均一となり、磁気特性がばらつくことになる。したがって、一次粒径のばらつきを低減することによって、磁気特性のばらつきも小さくすることができる。 Furthermore, the effect of homogenizing the primary particle size is such that, when nitriding is performed in a method for producing a grain-oriented electrical steel sheet using a steel material that does not contain an inhibitor component, the effect of suppressing variations in magnetic properties in the plate width direction is achieved. Have When the nitriding treatment is performed on the steel sheet not containing the inhibitor component, the inventors diffuse nitrogen in the steel by the nitriding treatment, and in the process, Si 3 N 4 precipitates are formed at the grain boundaries. This is confirmed by preliminary experiments. If the primary particle size is non-uniform, Si 3 N 4 formed at the grain boundary also has a non-uniform distribution when viewed macroscopically. In other words, when viewed macroscopically, precipitates are densely distributed at grain boundaries of fine primary particle size, while precipitates are sparsely distributed at coarse primary particle size particles, so secondary recrystallization The effect of precipitates on the magnetic field becomes non-uniform and the magnetic properties vary. Therefore, by reducing the variation in the primary particle size, the variation in the magnetic characteristics can be reduced.
次に、本発明の方向性電磁鋼板の素材に用いる鋼素材（スラブ）の成分組成について説明する。
Ｃ：０．００２〜０．１０ｍａｓｓ％
Ｃは、０．００２ｍａｓｓ％に満たないと、Ｃによる粒界強化効果が失われ、スラブに割れが生じるなどして、製造に支障を来たすようになる。一方、０．１０ｍａｓｓ％を超えると、脱炭焼鈍で、Ｃを磁気時効の起こらない０．００５ｍａｓｓ％以下に低減することが困難となる。よって、Ｃは０．００２〜０．１０ｍａｓｓ％の範囲とする。好ましくは０．０１０〜０．０８０ｍａｓｓ％の範囲である。
Next, the component composition of the steel material (slab) used for the material of the grain-oriented electrical steel sheet of the present invention will be described.
C: 0.002-0.10 mass%
If C is less than 0.002 mass%, the grain boundary strengthening effect due to C is lost, and cracks occur in the slab, which causes problems in production. On the other hand, when it exceeds 0.10 mass%, it becomes difficult to reduce C to 0.005 mass% or less at which no magnetic aging occurs by decarburization annealing. Therefore, C is in the range of 0.002 to 0.10 mass%. Preferably it is the range of 0.010-0.080 mass%.
Ｓｉ：２．０〜８．０ｍａｓｓ％
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。上記効果は、２．０ｍａｓｓ％未満では十分に得られず、一方、８．０ｍａｓｓ％を超えると、加工性が低下し、圧延して製造することが困難となる。よって、Ｓｉは２．０〜８．０ｍａｓｓ％の範囲とする。好ましくは２．５〜４．５ｍａｓｓ％の範囲である。
Si: 2.0 to 8.0 mass%
Si is an element necessary for increasing the specific resistance of steel and reducing iron loss. If the effect is less than 2.0 mass%, the effect is not sufficiently obtained. On the other hand, if it exceeds 8.0 mass%, the workability is lowered and it is difficult to roll and manufacture. Therefore, Si is set to a range of 2.0 to 8.0 mass%. Preferably it is the range of 2.5-4.5 mass%.
Ｍｎ：０．００５〜１．０ｍａｓｓ％
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、０．００５ｍａｓｓ％未満では十分ではなく、一方、１．０ｍａｓｓ％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０．００５〜１．０ｍａｓｓ％の範囲とする。好ましくは０．０２〜０．２０ｍａｓｓ％の範囲である。
Mn: 0.005 to 1.0 mass%
Mn is an element necessary for improving the hot workability of steel. If the effect is less than 0.005 mass%, it is not sufficient. On the other hand, if it exceeds 1.0 mass%, the magnetic flux density of the product plate is lowered. Therefore, Mn is set to a range of 0.005 to 1.0 mass%. Preferably it is the range of 0.02-0.20 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、インヒビターを利用する場合と、しない場合とに分けられるが、本発明の方向性電磁鋼板では、インヒビターを利用しないので、インヒビター形成成分であるＡｌ，Ｎ，ＳおよびＳｅの含有量は極力低減する必要があり、具体的には、Ａｌ：０．０１ｍａｓｓ％未満、Ｎ：０．００５０ｍａｓｓ％未満、Ｓ：０．００５０ｍａｓｓ％未満およびＳｅ：０．００３０ｍａｓｓ％未満に低減する必要がある。 Components other than C, Si and Mn are classified into cases where an inhibitor is used and cases where an inhibitor is not used in order to cause secondary recrystallization. However, the grain-oriented electrical steel sheet of the present invention does not use an inhibitor. Therefore, the contents of Al, N, S, and Se as inhibitor forming components must be reduced as much as possible. Specifically, Al: less than 0.01 mass%, N: less than 0.0050 mass%, S: 0.0. It is necessary to reduce to less than 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の上記成分以外の残部は、Ｆｅおよび不可避的不純物である。ただし、磁気特性の改善を目的として、Ｎｉ：０．００１〜１．５０ｍａｓｓ％、Ｃｒ：０．０１〜０．５０ｍａｓｓ％、Ｃｕ：０．０１〜０．５０ｍａｓｓ％、Ｐ：０．００５〜０．５０ｍａｓｓ％、Ｓｂ：０．００５〜０．５０ｍａｓｓ％、Ｓｎ：０．００５〜０．５０ｍａｓｓ％、Ｂｉ：０．００５〜０．５０ｍａｓｓ％、Ｍｏ：０．００５〜０．１００ｍａｓｓ％、Ｔｅ：０．０００５〜０．０１０ｍａｓｓ％、Ｎｂ：０．００１０〜０．０１０ｍａｓｓ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いてもよい。 The remainder other than the said component of the steel raw material used for the grain-oriented electrical steel sheet of this invention is Fe and an unavoidable impurity. However, for the purpose of improving magnetic properties, Ni: 0.001-1.50 mass%, Cr: 0.01-0.50 mass%, Cu: 0.01-0.50 mass%, P: 0.005-0 .50 mass%, Sb: 0.005-0.50 mass%, Sn: 0.005-0.50 mass%, Bi: 0.005-0.50 mass%, Mo: 0.005-0.100 mass%, Te: You may contain suitably 1 type (s) or 2 or more types chosen from 0.0005-0.010 mass% and Nb: 0.0010-0.010 mass.
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。
前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、常法の造塊−分塊圧延法または連続鋳造法で鋼素材（スラブ）を製造してもよいし、あるいは、直接鋳造法で１００ｍｍ以下の厚さの薄鋳片を製造してもよい。上記スラブは、常法に従い、１２５０℃以下の温度に再加熱した後、熱間圧延に供する。なお、鋳造後、スラブを再加熱することなく直ちに熱間圧延に供してもよい。また、薄鋳片の場合には、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。
Next, the manufacturing method of the grain-oriented electrical steel sheet of this invention is demonstrated.
A steel material (slab) may be manufactured by a conventional ingot-bundling rolling method or a continuous casting method after melting the steel having the above-described component composition by a conventional refining process, or directly. A thin slab having a thickness of 100 mm or less may be manufactured by a casting method. The slab is subjected to hot rolling after reheating to a temperature of 1250 ° C. or lower according to a conventional method. In addition, you may use for a hot rolling immediately after casting, without reheating a slab. In the case of a thin slab, the hot rolling may be omitted and the process may proceed as it is.
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、二次再結晶粒の成長が阻害される。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。ただし、熱延板焼鈍は必須の工程ではない。 Next, the hot-rolled sheet obtained by hot rolling is subjected to hot-rolled sheet annealing as necessary. The 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 it is less than 800 degreeC, the band structure formed by hot rolling will remain, it will become difficult to obtain the primary recrystallized structure of a sized grain, and the growth of a secondary recrystallized grain will be inhibited. On the other hand, when the temperature exceeds 1150 ° C., the grain size after the hot-rolled sheet annealing is excessively coarsened, so that it becomes difficult to obtain a primary recrystallized structure of sized particles. However, hot-rolled sheet annealing is not an essential process.
熱延後あるいは熱延板焼鈍後の鋼板は、１回の冷間圧延または中間焼鈍を挟む２回以上の冷間圧延により最終板厚の冷延板とする。上記中間焼鈍の焼鈍温度は、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、さらに、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性が低下する。一方、１２００℃を超えると、熱延板焼鈍と同様、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からである。 The steel sheet after hot-rolling or after hot-rolled sheet annealing is made into a cold-rolled sheet having a final sheet thickness by one or more cold rolling or two or more cold rollings sandwiching intermediate annealing. The annealing temperature of the intermediate annealing is preferably in the range of 900 to 1200 ° C. When the temperature is lower than 900 ° C., the recrystallized grains after the intermediate annealing become finer, and the Goss nuclei in the primary recrystallized structure are reduced to deteriorate the magnetic properties of the product plate. On the other hand, when the temperature exceeds 1200 ° C., the crystal grains become too coarse as in the hot-rolled sheet annealing, and it becomes difficult to obtain a primary recrystallized structure of the sized grains.
また、最終板厚とする冷間圧延（最終冷間圧延）は、冷間圧延時の鋼板温度を１００〜３００℃の温度に上昇させて行う温間圧延としたり、冷間圧延の途中で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、磁気特性を向上するのに有効である。 Moreover, the cold rolling (final cold rolling) which makes the final sheet thickness is a warm rolling performed by raising the steel plate temperature during the cold rolling to a temperature of 100 to 300 ° C., or 100 during the cold rolling. Applying an aging treatment once or a plurality of times at a temperature of ˜300 ° C. is effective in improving the primary recrystallization texture and improving the magnetic properties.
最終板厚とした冷延板は、その後、脱炭焼鈍を兼ねた一次再結晶焼鈍を施す。
この一次再結晶焼鈍における焼鈍温度は、脱炭焼鈍を伴う場合は、脱炭反応を速やかに進行させる観点から、８００〜９００℃の範囲とするのが好ましく、また、雰囲気は湿潤雰囲気とするのが好ましい。ただし、脱炭が不要なＣ：０．００５ｍａｓｓ％以下の鋼素材を用いる場合は、この限りではない。また、一次再結晶焼鈍と脱炭焼鈍を別々に行ってもよい。
The cold-rolled sheet having the final thickness is then subjected to primary recrystallization annealing that also serves as decarburization annealing.
The annealing temperature in the primary recrystallization annealing is preferably in the range of 800 to 900 ° C. from the viewpoint of promptly proceeding the decarburization reaction when decarburization annealing is involved, and the atmosphere is a moist atmosphere. Is preferred. However, this is not the case when a steel material with C: 0.005 mass% or less that does not require decarburization is used. Moreover, you may perform a primary recrystallization annealing and a decarburization annealing separately.
ここで、本発明において重要なことは、上記一次再結晶焼鈍の加熱過程においては、２００〜７００℃間を５０℃／ｓ以上で急速加熱するとともに、その加熱途中の２５０〜６００℃間のいずれかの温度で１〜１０秒間保持する保定処理を施すことである。ここで、上記２００〜７００℃間における昇温速度（５０℃／ｓ以上）は、前述したように、保定する時間を除いた時間における昇温速度である。また、上記保定処理は、２５０〜６００℃間のいずれかの温度で行えばよいが、上記温度は必ずしも一定でなくてもよく、±１０℃／ｓ以下の温度変化であれば、保定と同様の効果を得ることができるので、±１０℃／ｓの範囲内で昇温もしくは降温してもよい。 Here, in the present invention, what is important is that in the heating process of the primary recrystallization annealing, between 200 to 700 ° C. is rapidly heated at 50 ° C./s or more, and any of 250 to 600 ° C. during the heating is performed. It is to perform a retaining process for holding at that temperature for 1 to 10 seconds. Here, the temperature increase rate (50 ° C./s or more) between 200 and 700 ° C. is the temperature increase rate in the time excluding the holding time, as described above. Further, the holding treatment may be performed at any temperature between 250 to 600 ° C., but the temperature does not necessarily have to be constant, and is similar to the holding as long as the temperature change is ± 10 ° C./s or less. Thus, the temperature may be raised or lowered within a range of ± 10 ° C./s.
さらに、本発明において重要なことは、上記急速加熱に続く加熱過程における７００〜８００℃間の滞留時間を５〜３５秒の範囲とする必要があることである。なお、上記滞留時間は、サブスケールが過多となるのを防止する観点からは、１５秒以下とするのが好ましい。 Furthermore, what is important in the present invention is that the residence time between 700 and 800 ° C. in the heating process following the rapid heating needs to be in the range of 5 to 35 seconds. The residence time is preferably 15 seconds or less from the viewpoint of preventing the subscale from becoming excessive.
一次再結晶焼鈍（脱炭焼鈍）を施した鋼板は、その後、窒化処理を施す。
窒化処理のタイミングは、一次再結晶焼鈍後、温度を室温まで下げることなく、続けて行ってもよいし、一次再結晶焼鈍が終了後、一旦、室温まで冷却した後、改めて窒化処理を行ってもよい。
また、窒化処理の方法は、窒化量を制御できればいずれの方法でもよく、例えば、ＮＨ３雰囲気ガスを用いて、コイル状態のまま、あるいは、コイルを巻き戻してストリップ（鋼帯）の状態で窒化するガス窒化法や、ガス窒化法よりも窒化能に優れる塩浴窒化法を用いてもよい。
The steel sheet subjected to primary recrystallization annealing (decarburization annealing) is then subjected to nitriding treatment.
The timing of the nitriding treatment may be continued after the primary recrystallization annealing without lowering the temperature to room temperature, or after the primary recrystallization annealing is completed, the nitriding treatment is once performed after cooling to room temperature. Also good.
The nitriding method may be any method as long as the amount of nitridation can be controlled. For example, nitriding is performed in the state of a strip (steel strip) by using NH 3 atmosphere gas in a coil state or by unwinding the coil. Alternatively, a gas nitriding method or a salt bath nitriding method having a nitriding ability superior to that of the gas nitriding method may be used.
なお、上記窒化処理による鋼板中の窒素の増量分（増窒量）は０．００５０〜０．１０００ｍａｓｓ％の範囲とするのが好ましい。増窒量が０．００５０ｍａｓｓ％未満では、窒化処理による磁気特性向上効果が十分に得られず、一方、０．１０００ｍａｓｓ％を超えると、窒化珪素の析出量が過多となり、二次再結晶が生じ難くなる。より好ましくは０．０２００〜０．０７００ｍａｓｓ％の範囲である。 In addition, it is preferable to make the amount of increase (nitrogen increase amount) of the nitrogen in the steel plate by the said nitriding process into the range of 0.0050-0.1000 mass%. If the amount of nitrogen increase is less than 0.0050 mass%, the effect of improving the magnetic properties by nitriding cannot be obtained sufficiently. On the other hand, if it exceeds 0.1000 mass%, the amount of silicon nitride deposited becomes excessive and secondary recrystallization occurs. It becomes difficult. More preferably, it is the range of 0.0200-0.0700 mass%.
上記一次再結晶焼鈍を施した鋼板は、鉄損特性やトランスの騒音を重視する場合には、ＭｇＯを主体とする焼鈍分離剤を鋼板表面に塗布、乾燥した後、仕上焼鈍を施し、Ｇｏｓｓ方位に高度に集積させ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するのが好ましい。一方、打抜加工性を重視し、フォルステライト被膜を形成しない場合には、焼鈍分離剤を適用しないか、あるいは、シリカやアルミナ等を主体とした焼鈍分離剤を用いて仕上焼鈍を施すのが好ましい。なお、フォルステライト被膜を形成しない場合、焼鈍分離剤の塗布に水分を持ち込まない静電塗布を行うことも有効である。また、焼鈍分離剤に代えて、耐熱無機材料シート（シリカ、アルミナ、マイカ）を用いてもよい。 The steel sheet subjected to the primary recrystallization annealing is applied with an annealing separator mainly composed of MgO on the surface of the steel sheet when the core loss characteristic and the noise of the transformer are emphasized, and then subjected to finish annealing, and Goss orientation It is preferable to develop a secondary recrystallized structure that is highly accumulated in the film and to form a forsterite film. On the other hand, when emphasizing the punching workability and not forming the forsterite film, it is not necessary to apply an annealing separator or to perform a final annealing using an annealing separator mainly composed of silica or alumina. preferable. In addition, when a forsterite film is not formed, it is also effective to perform electrostatic coating without bringing moisture into the coating of the annealing separator. Further, a heat resistant inorganic material sheet (silica, alumina, mica) may be used in place of the annealing separator.
仕上焼鈍における焼鈍温度は、二次再結晶を発現し、完了させるためには８００℃以上の温度に昇温し、２０時間以上保持することが好ましい。なお、鉄損特性を重視するために純化処理を施す場合や、トランスの騒音を低下させるためにフォルステライト被膜を形成させる場合には、二次再結晶を完了させた後、１２５０℃程度の温度まで昇温するのが好ましい。 The annealing temperature in the finish annealing is preferably raised to a temperature of 800 ° C. or higher and maintained for 20 hours or longer in order to develop and complete secondary recrystallization. In addition, when performing a purification process in order to attach importance to the iron loss characteristic, or in the case of forming a forsterite film in order to reduce the noise of the transformer, after the secondary recrystallization is completed, a temperature of about 1250 ° C. It is preferable to raise the temperature up to.
仕上焼鈍後の鋼板は、その後、水洗やブラッシング、酸洗等で、鋼板表面に付着した未反応の焼鈍分離剤を除去した後、平坦化焼鈍を施して形状矯正することが、鉄損の低減には有効である。これは、仕上焼鈍は、通常、コイル状態で行うため、コイルの巻き癖が付き、これが原因で、鉄損測定時に特性が劣化することがあるためである。 After finishing annealing, the steel sheet can be cleaned by washing, brushing, pickling, etc., removing unreacted annealing separator adhering to the steel sheet surface, and then flattening annealing to correct the shape, thereby reducing iron loss. Is effective. This is because the finish annealing is usually performed in a coil state, so that the coil has wrinkles and this may cause deterioration in characteristics when measuring iron loss.
さらに、鋼板を積層して使用する場合には、上記平坦化焼鈍において、あるいは、その前後において、鋼板表面に絶縁被膜を被成することが有効である。特に、鉄損の低減を図るためには、絶縁被膜として、鋼板に張力を付与する張力付与被膜を適用するのが好ましい。張力付与被膜の形成には、バインダーを介して張力被膜を塗布する方法や、物理蒸着法や化学蒸着法により無機物を鋼板表層に蒸着させる方法を採用することで、被膜密着性に優れかつ著しく鉄損低減効果が大きい絶縁被膜を形成することができるので、より好ましい。 Furthermore, in the case where the steel plates are laminated and used, it is effective to form an insulating film on the steel plate surface in the above-described flattening annealing or before and after that. In particular, in order to reduce iron loss, it is preferable to apply a tension-imparting film that imparts tension to the steel sheet as the insulating film. For the formation of the tension-imparting film, a method of applying a tension film through a binder or a method of depositing an inorganic substance on the surface of a steel sheet by a physical vapor deposition method or a chemical vapor deposition method has excellent film adhesion and remarkably iron. Since an insulating film having a large loss reducing effect can be formed, it is more preferable.
また、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好ましい。処理方法としては、一般的に実施されている、最終製品板に溝を形成したり、電子ビーム照射やレーザ照射、プラズマ照射等によって線状または点状に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等の中間工程の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。 Moreover, in order to further reduce the iron loss, it is preferable to perform a magnetic domain fragmentation process. As a processing method, a method of generally forming a groove in the final product plate, introducing a thermal strain or an impact strain in a linear or dotted manner by electron beam irradiation, laser irradiation, plasma irradiation, or the like, For example, a method of forming a groove by etching the steel sheet surface in an intermediate process such as a steel sheet cold-rolled to the final thickness can be used.
Ｃ：０．０２３ｍａｓｓ％、Ｓｉ：３．４５ｍａｓｓ％、Ｍｎ：０．２２ｍａｓｓ％、Ａｌ：０．００８７ｍａｓｓ％およびＮ：０．００４５ｍａｓｓ％、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、１２２０℃の温度に再加熱した後、熱間圧延して、板厚２．７ｍｍの熱延板とし、１０００℃×４５秒の熱延板焼鈍を施した後、２００℃の温間圧延により最終板厚０．３０ｍｍの冷延鋼板に仕上げた。
その後、上記鋼板に、５０ｖｏｌ％Ｈ２−５０ｖｏｌ％Ｎ２の湿潤雰囲気下で、８５０℃×１２０秒の脱炭焼鈍伴う一次再結晶焼鈍を施した。この際、８５０℃までの加熱過程における２００〜７００℃間の昇温速度を、表１に記載のごとく変化させるとともに、その加熱途中において、表１に記載の温度と時間の保定処理を施した。さらに、上記加熱過程における７００〜８００℃間の滞留時間を、同じく表１に記載のごとく変化させた。
C: 0.023 mass%, Si: 3.45 mass%, Mn: 0.22 mass%, Al: 0.0087 mass% and N: 0.0045 mass%, the balance being Fe and inevitable impurities steel slab is continuously cast After being reheated to a temperature of 1220 ° C., hot-rolled to form a hot-rolled sheet having a thickness of 2.7 mm, subjected to hot-rolled sheet annealing at 1000 ° C. for 45 seconds, and then heated to a temperature of 200 ° C. A cold rolled steel sheet having a final sheet thickness of 0.30 mm was finished by hot rolling.
Thereafter, the steel sheet was subjected to primary recrystallization annealing with decarburization annealing at 850 ° C. for 120 seconds in a wet atmosphere of 50 vol% H 2 -50 vol% N 2 . At this time, the heating rate between 200 and 700 ° C. in the heating process up to 850 ° C. was changed as shown in Table 1, and the temperature and time holding treatment shown in Table 1 was performed during the heating. . Further, the residence time between 700 and 800 ° C. in the heating process was changed as shown in Table 1.
なお、上記一次再結晶焼鈍後の鋼板からサンプルを採取し、板幅方向に１００ｍｍおきに板幅方向断面の一次粒径を測定し、板幅方向におけるばらつきを調査した。なお、上記冷延板の板幅は１２００ｍｍのものであるため、板幅端部５０ｍｍから１００ｍｍピッチで測定したときの測定箇所は全幅で１２箇所となる。
ここで、上記一次粒径の測定は、板厚断面を５ｍａｓｓ％ナイタール液でエッチングして粒界を現出させ、板厚０．２７ｍ×板幅方向ｌ０ｍｍの範囲の画像を画像処理して円相当径の平均を求め、その値をその箇所の一次粒径とし、板幅方向１２箇所の平均を求めた。また、一次粒径のばらつきは、上記１２箇所の標準偏差を求め、その値を平均値で除し、それに１００を掛けた値（％）とした。
In addition, the sample was extract | collected from the steel plate after the said primary recrystallization annealing, the primary particle size of the board width direction cross section was measured every 100 mm in the plate width direction, and the dispersion | variation in a plate width direction was investigated. In addition, since the plate width of the said cold rolled sheet is 1200 mm, the measurement location when measuring with a 100 mm pitch from 50 mm of board width edge parts will be 12 places in a full width.
Here, the primary particle size is measured by etching the cross section of the plate with a 5 mass% nital solution to reveal the grain boundary, and image-processing an image in the range of 0.27 m in plate thickness × 10 mm in the plate width direction. The average of the equivalent diameters was obtained, the value was taken as the primary particle size of the part, and the average of 12 places in the plate width direction was obtained. Further, the variation in primary particle size was determined by obtaining the standard deviation at the above 12 locations, dividing that value by the average value, and multiplying it by 100 (%).
次いで、上記一次再結晶焼鈍後の鋼板に、アンモニア雰囲気下で、７５０℃×３０秒の窒化処理を施した。この窒化処理による鋼板中の増窒量は０．０１４７〜０．０２８７ｍａｓｓ％の範囲であった。
その後、上記窒化処理後の鋼板表面にＭｇＯを主体とする焼鈍分離剤を塗布、乾燥した後、１２００℃×１０時間の純化処理を伴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、昇温時および降温時はＮ２とした。
Next, the steel sheet after the primary recrystallization annealing was subjected to nitriding treatment at 750 ° C. for 30 seconds in an ammonia atmosphere. The amount of nitrogen increase in the steel sheet by this nitriding treatment was in the range of 0.0147 to 0.0287 mass%.
Thereafter, an annealing separator mainly composed of MgO was applied to the surface of the steel sheet after the nitriding treatment, dried, and then subjected to finish annealing with a purification treatment at 1200 ° C. for 10 hours. The atmosphere of the finish annealing was H 2 at the time of maintaining at 1200 ° C. for the purification treatment, and N 2 at the time of temperature increase and temperature decrease.
斯くして得た仕上焼鈍後の鋼板から、板幅方向に幅１００ｍｍ×長さ５００ｍｍの試験片を各々１０枚ずつ採取し、ＪＩＳ Ｃ２５５６に記載の方法で鉄損Ｗ１７／５０を測定し、それらの平均値を求めた。
その結果を、一次粒径の測定結果と併せて表１に示した。この表から、本発明を適合した鋼板は、一次粒径が小さく、鉄損特性にも優れていることがわかる。
Ten pieces of test pieces each having a width of 100 mm and a length of 500 mm in the sheet width direction were collected from the steel sheet after finish annealing thus obtained, and the iron loss W 17/50 was measured by the method described in JIS C2556. Their average value was determined.
The results are shown in Table 1 together with the measurement results of the primary particle size. From this table, it can be seen that the steel sheet adapted to the present invention has a small primary particle size and excellent iron loss characteristics.
表２に記載の成分組成を有し、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、１３００℃の温度に再加熱した後、熱間圧延して板厚２．２ｍｍの熱延板とし、１０２０℃×２０秒の熱延板焼鈍を施した後、冷間圧延して最終板厚０．２３ｍｍの冷延板に仕上げた。
その後、６０ｖｏｌ％Ｈ２−４０ｖｏｌ％Ｎ２の湿潤雰囲気下で、８４０℃×１００秒の脱炭焼鈍を伴う一次再結晶焼鈍を施した。この際、８４０℃までの加熱過程における２００〜７００℃間の昇温速度は１２５℃／ｓとし、さらにその加熱途中の４５０℃の温度で、１．５秒間保持する保定処理を施した。また、加熱過程の７００〜８００℃間の滞留時間は１０秒とした。なお、上記一次再結晶焼鈍後の鋼板について、実施例１と同様にして板幅方向の一次粒径を測定してばらつきの大きさを求めたところ、４．４〜８．３％の範囲であった。
A steel slab having the composition shown in Table 2 with the balance being Fe and inevitable impurities is manufactured by a continuous casting method, reheated to a temperature of 1300 ° C., and then hot-rolled to a thickness of 2.2 mm. The hot rolled sheet was subjected to hot rolled sheet annealing at 1020 ° C. for 20 seconds, and then cold rolled to finish a cold rolled sheet having a final sheet thickness of 0.23 mm.
Then, primary recrystallization annealing with decarburization annealing at 840 ° C. for 100 seconds was performed in a wet atmosphere of 60 vol% H 2 -40 vol% N 2 . Under the present circumstances, the temperature increase rate between 200-700 degreeC in the heating process to 840 degreeC was 125 degreeC / s, and also the retention process hold | maintained for 1.5 second at the temperature of 450 degreeC in the middle of the heating was performed. The residence time between 700 and 800 ° C. in the heating process was 10 seconds. In addition, about the steel plate after the said primary recrystallization annealing, when the primary particle size was measured like the Example 1 and the magnitude | size of dispersion | variation was calculated | required, it is in the range of 4.4 to 8.3%. there were.
次いで、上記一次再結晶焼鈍後の鋼板に、アンモニア雰囲気下で、５００℃×３００秒の窒化処理を施した。この窒化処理による鋼板中の増窒量は０．０３５９〜０．０５４０ｍａｓｓ％の範囲であった。
その後、上記窒化処理後の鋼板表面にＭｇＯを主体とする焼鈍分離剤を塗布、乾燥した後、１２３０℃×３時間の純化処理を伴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、昇温時および降温時はＡｒとした。
Next, the steel sheet after the primary recrystallization annealing was subjected to nitriding treatment at 500 ° C. for 300 seconds in an ammonia atmosphere. The amount of increase in nitrogen in the steel sheet by this nitriding treatment was in the range of 0.0359 to 0.0540 mass%.
Thereafter, an annealing separator mainly composed of MgO was applied to the surface of the steel sheet after the nitriding treatment, dried, and then subjected to finish annealing with a purification treatment of 1230 ° C. × 3 hours. The atmosphere of the finish annealing was H 2 at the time of maintaining at 1200 ° C. for the purification treatment, and Ar at the time of temperature increase and temperature decrease.
斯くして得た仕上焼鈍後の鋼板から、板幅方向に幅１００ｍｍ×長さ５００ｍｍの試験片を各々１０枚ずつ採取し、ＪＩＳ Ｃ２５５６に記載の方法で鉄損Ｗ１７／５０を測定し、それらの平均値を求めた。
その結果を、一次粒径の測定結果と併せて、表２に示した。この表から、本発明を適合する条件で製造することにより、一次粒径のばらつきが小さく、低鉄損の方向性電磁鋼板を得ることができることがわかる。
Ten pieces of test pieces each having a width of 100 mm and a length of 500 mm in the sheet width direction were collected from the steel sheet after finish annealing thus obtained, and the iron loss W 17/50 was measured by the method described in JIS C2556. Their average value was determined.
The results are shown in Table 2 together with the measurement results of the primary particle size. From this table, it can be seen that by producing the present invention under suitable conditions, it is possible to obtain a grain-oriented electrical steel sheet having a small variation in primary particle size and low iron loss.
本発明の技術は、冷延鋼板の集合組織の制御に適しているので、加工性が要求される自動車用鋼板等の製造方法にも適用することができる。 Since the technique of the present invention is suitable for controlling the texture of cold-rolled steel sheets, it can also be applied to a method for manufacturing automobile steel sheets and the like that require workability.
Claims (3)
前記一次再結晶焼鈍の加熱過程における２００〜７００℃間を５０℃／ｓ以上で急速加熱し、かつ、２５０〜６００℃間のいずれかの温度で１〜１０秒間保持する保定処理を施すとともに、続く７００〜８００℃間の領域における滞留時間を５秒以上とすることによって、一次再結晶焼鈍後の一次粒径の鋼板板幅方向のばらつきを１０％以内とすることを特徴とする方向性電磁鋼板の製造方法。 C: 0.002-0.10 mass%, Si: 2.0-8.0 mass%, Mn: 0.005-1.0 mass%, Al: less than 0.01 mass%, N: less than 0.0050 mass%, Se : Less than 0.0030 mass% and S: less than 0.0050 mass%, with the balance being Fe and inevitable impurities, hot rolled into a hot-rolled sheet, once or two or more times with intermediate annealing After cold rolling to a cold-rolled sheet with the final thickness, subjecting it to primary recrystallization annealing and performing nitriding during or after primary recrystallization annealing, an annealing separator is applied to the steel sheet surface. In the manufacturing method of the grain-oriented electrical steel sheet that is applied and finish-annealed,
In the heating process of the primary recrystallization annealing, between 200 and 700 ° C. is rapidly heated at 50 ° C./s or more, and a holding treatment is performed for 1 to 10 seconds at any temperature between 250 and 600 ° C., and By setting the residence time in the subsequent region of 700 to 800 ° C. to 5 seconds or more, the variation in the steel plate width direction of the primary grain size after the primary recrystallization annealing is within 10%. A method of manufacturing a steel sheet.
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| JP2012184497A (en) * | 2011-02-17 | 2012-09-27 | Jfe Steel Corp | Method for producing grain-oriented electromagnetic steel sheet |
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| US20180371572A1 (en) * | 2015-12-23 | 2018-12-27 | Posco | Grain-oriented electrical steel sheet and method for manufacturing the same |
| JP2020084303A (en) * | 2018-11-30 | 2020-06-04 | Ｊｆｅスチール株式会社 | Production process of grain-oriented electromagnetic steel sheet |
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