JP4207231B2 - Method for producing non-oriented electrical steel sheet - Google Patents
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Description
【０００１】
【発明が属する技術分野】
この発明は、リジングの発生がない優れた表面性状を有し且つ鉄損の低い無方向性電磁鋼板の製造方法に関する。
【０００２】
【従来の技術】
無方向性電磁鋼板は、Ｓｉ含有量が１．５ｗｔ％以上になると冷間圧延後の製品にリジングと呼ばれる表面性状不良が発生し易くなるため、通常、Ｓｉ含有量が１．５ｗｔ％以上の無方向性電磁鋼板の製造では熱延板焼鈍を実施している。
【０００３】
【発明が解決しようとする課題】
しかし、熱延板焼鈍は製造コストの著しい上昇を招くため、これに代わる方法として、熱延コイルを高温で巻き取り、熱延板を自己焼鈍させる等の技術が検討されている。このような熱延板の自己焼鈍を行うためには、コイル巻取り後の温度確保のために熱延板を高温で仕上げる必要があり、そのためにはスラブ加熱温度を高める必要がある。しかし、このようにスラブ加熱温度を高めると鋼中の硫化物や窒化物が再固溶するため仕上焼鈍時の粒成長性が低下し、磁気特性が低下するという問題がある。
【０００４】
したがって本発明の目的は、このような従来の課題を解決し、熱延板焼鈍を施さなくてもリジング発生がない優れた表面性状を有し且つ鉄損が低い無方向性電磁鋼板の製造方法を提供することにある。
【０００５】
【課題を解決するための手段】
本発明者らは、熱延板焼鈍を施さなくともリジング発生を適切に回避でき、且つ鉄損特性にも優れた無方向性電磁鋼板の製造条件について検討を行い、その結果、下記のような知見を得た。
(1) Ｃ：０〜０．００５ｗｔ％、Ｐ：０〜０．１ｗｔ％、Ｎ：０〜０．００５ｗｔ％、Ｓｉ：１．５〜４．０ｗｔ％、Ｍｎ：０．０５〜１．０ｗｔ％、Ｓｏｌ．Ａｌ：０．１〜１．０ｗｔ％、Ｓ：０〜０．００７ｗｔ％、残部が実質的にＦｅからなる組成のスラブを素材として無方向性電磁鋼板を製造する場合、熱延板焼鈍を施すことなく仕上焼鈍後の鉄損を低下させるためには、スラブ加熱温度を低温加熱領域である１１５０℃以下にする必要がある。
【０００６】
(2) また、スラブを上記(1)のように低温加熱することによって、熱間圧延後に微細な析出物が析出せず、熱延板の再結晶温度が低下する。
(3) 但し、このようなスラブの低温加熱では、粗圧延後１０００℃以上の温度域への再加熱を実施しない限り、所定の巻取温度を確保することが極めて困難となる。
(4) 一方、粗圧延後の再加熱温度が１１５０℃を超えると、析出物が再固溶するため仕上焼鈍後の鉄損が低下する。
【０００７】
(5) リジングに対しては仕上圧延前組織を再結晶させることが重要であり、このためには、再結晶に必要な歪みエネルギーを粗圧延段階において与えるために、粗圧延で圧下率６０％以上の圧下を施し、しかる後に１０００℃以上、保持時間２秒以上の加熱処理を施すことが有効である。
(6) 但し、この加熱保持時間が１０秒を超えると一部に析出物の再固溶が起こり、最終の鉄損特性が劣化してしまうため、加熱保持時間は１０秒以下とし、その後、仕上圧延を行う必要がある。
(7) さらに、上記熱延板を６５０℃以上で巻き取ることによって熱延板が再結晶し、リジングの回避に有効に作用する。
【０００８】
本発明はこのような知見に基づきなされたもので、その特徴は、Ｃ：０〜０．００５ｗｔ％、Ｐ：０〜０．１ｗｔ％、Ｎ：０〜０．００５ｗｔ％、Ｓｉ：１．５〜４．０ｗｔ％、Ｍｎ：０．０５〜１．０ｗｔ％、Ｓｏｌ．Ａｌ：０．１〜１．０ｗｔ％、Ｓ：０〜０．００７ｗｔ％、残部Ｆｅおよび不可避不純物からなる組成のスラブを熱間圧延した後、冷間圧延および仕上焼鈍を経て無方向性電磁鋼板を製造する方法であって、熱間圧延を行うに際し、スラブを１１５０℃以下の温度に加熱した後、粗圧延機にて６０％以上の圧下率で粗圧延し、引き続き該粗圧延材を１０００〜１１５０℃の温度に加熱してこの温度範囲に２〜１０秒間保持する加熱処理を施した後、仕上圧延を行い、６５０℃以上で巻き取ることを特徴とする無方向性電磁鋼板の製造方法である。
【０００９】
【発明の実施の形態】
以下、本発明の詳細をその限定理由とともに説明する。
本発明では、特定の成分組成のスラブを素材とし、これを熱間圧延する際に、スラブを１１５０℃以下の温度に加熱した後、粗圧延機にて６０％以上の圧下率で粗圧延し、引き続き該粗圧延材を１０００〜１１５０℃の温度に加熱昇温してこの温度範囲に２〜１０秒間保持する加熱処理を施した後、仕上圧延を行い、６５０℃以上で巻き取る。
【００１０】
先ず、スラブ加熱温度および粗圧延後の加熱処理における加熱温度（再加熱温度）がリジングの発生および仕上焼鈍後の鉄損に及ぼす影響を調査するため、以下のような試験を行った。
Ｃ：０．００２２ｗｔ％、Ｓｉ：１．７６ｗｔ％、Ｍｎ：０．２９ｗｔ％、Ｐ：０．０５ｗｔ％、Ｓ：０．００３３ｗｔ％、Ｓｏｌ．Ａｌ：０．３４ｗｔ％、Ｎ：０．００２２ｗｔ％の組成の鋼を溶製し、これを鋳造してスラブを作製した。このスラブを常温から１１００℃と１２００℃にそれぞれに加熱して圧下率７０％で粗圧延した後、引き続き高周波加熱装置を用いて９００〜１２５０℃の範囲に加熱昇温し、その温度に５秒間保持する加熱処理を施した後、板厚２．０ｍｍまで仕上圧延を行い、７００℃で巻き取った。次いで、この熱延板を酸洗した後、板厚０．５ｍｍまで冷間圧延し、さらに２５％Ｈ2−７５％Ｎ2雰囲気中で９００℃×１分間の仕上焼鈍を行った。
【００１１】
このようにして得られた鋼板の鉄損とリジング発生の有無を図１に示す。これによれば、鉄損についてはスラブ加熱温度を１１００℃とし、粗圧延後の加熱処理における加熱温度を１１５０℃以下とした場合に優れた鉄損が得られている。これに対して、スラブ加熱温度を１２００℃とした場合には、粗圧延後の加熱処理による鉄損低減化効果は全く得られていない。粗圧延後の加熱処理による鉄損低減効果が得られるスラブ加熱温度についてさらに検討を行った結果、上記鉄損低減効果が得られるスラブ加熱温度の上限はほぼ１１５０℃であることが判った。一方、スラブ加熱温度を１１００℃とした場合のリジングの発生の有無については、粗圧延後の加熱温度が１０００℃以上の場合にリジングが減少する傾向があることが判る。
以上の理由から本発明では、スラブを常温から加熱する際のスラブ加熱温度を１１５０℃以下とし、且つ粗圧延後の加熱処理における加熱温度を１０００〜１１５０℃とする。但し、スラブ加熱温度が９５０℃未満では熱間圧延自体が困難となるため、スラブ加熱温度の下限は９５０℃とすることが好ましい。
【００１２】
次に、粗圧延後の加熱処理における加熱保持時間がリジングの発生および仕上焼鈍後の鉄損に及ぼす影響を調査するため、以下のような試験を行った。
Ｃ：０．００３０ｗｔ％、Ｓｉ：１．７９ｗｔ％、Ｍｎ：０．３４ｗｔ％、Ｐ：０．０４ｗｔ％、Ｓ：０．００２８ｗｔ％、Ｓｏｌ．Ａｌ：０．３２ｗｔ％、Ｎ：０．００２１ｗｔ％の組成の鋼を溶製し、これを鋳造してスラブを作製した。このスラブを常温から１１００℃に加熱して圧下率７０％で粗圧延した後、引き続き高周波加熱装置を用いて１１５０℃に加熱昇温し、この温度に１〜２０秒間保持する加熱処理を施した後、板厚２．０ｍｍまで仕上圧延を行い、７００℃で巻き取った。次いで、この熱延板を酸洗した後、板厚０．５ｍｍまで冷間圧延し、さらに２５％Ｈ2−７５％Ｎ2雰囲気中で９００℃×１分間の仕上焼鈍を行った。
【００１３】
このようにして得られた鋼板の鉄損とリジング発生の有無を図２に示す。これによれば、粗圧延後の加熱処理における保持時間が１０秒を超えると鉄損が劣化する傾向にあり、一方、保持時間が２秒未満ではリジングが発生する傾向があることが判る。
以上の理由から本発明では、粗圧延後の加熱処理における１０００〜１１５０℃での保持時間を２〜１０秒間とし、その後、仕上圧延を行うものとする。
【００１４】
さらに、粗圧延の圧下率がリジングの発生に及ぼす影響を調査するため、以下のような試験を行った。
図２の試験で用いたスラブと同じ組成のスラブを１１００℃に加熱して圧下率４０〜９０％で粗圧延した。引き続き、この粗圧延材を高周波加熱装置を用いて１１５０℃に加熱昇温し、この温度に５秒間保持する加熱処理を施した後、板厚２．０ｍｍまで仕上圧延を行い、７００℃で巻き取った。次いで、この熱延板を酸洗した後、板厚０．５ｍｍまで冷間圧延し、さらに２５％Ｈ2−７５％Ｎ2雰囲気中で９００℃×１分間の仕上焼鈍を行った。
表１は、粗圧延を各圧下率で実施した材料について仕上焼鈍後のリジングの有無を示したものであり、圧下率６０％以上においてリジング発生が回避されていることが判る。このため本発明では、粗圧延の圧下率を６０％以上とする。但し、粗圧延の圧下率が９０％を超えるとミルの負荷増大により熱間圧延が不可能となるため、粗圧延の圧下率の上限は９０％とすることが好ましい。
【００１５】
【表１】
次に、鋼組成の限定理由について説明する。
Ｓｉは鋼板の固有抵抗を上げるのに有効な元素であり、この作用を得るためには１．５ｗｔ％以上の添加が必要であるが、４．０ｗｔ％を超えると飽和磁束密度の低下に伴い磁束密度が低下する。このためＳｉは１．５〜４．０ｗｔ％とする。
ＡｌはＳｉと同様、固有抵抗を上げるために有効な元素であるが、Ｓｏｌ．Ａｌが１．０ｗｔ％を超えると飽和磁束密度の低下に伴い磁束密度が低下する。一方、Ｓｏｌ．Ａｌが０．１ｗｔ％未満ではＡｌＮが微細化し、粒成長性が低下する。このためＳｏｌ．Ａｌは０．１〜１．０ｗｔ％とする。
【００１７】
Ｃは磁気時効の問題があるため、０〜０．００５ｗｔ％（無添加の場合を含む）とする。
Ｍｎは熱間圧延時の赤熱脆性を防止するために０．０５ｗｔ％以上添加する必要があるが、１．０ｗｔ％超えると磁束密度を低下させるので、０．０５〜１．０ｗｔ％とする。
Ｐは鋼板の打ち抜き性を改善するために有効な元素であるが、０．１ｗｔ％を超えて添加すると鋼板が脆化するため、０〜０．１ｗｔ％（無添加の場合を含む）とする。
【００１８】
Ｓは微細な析出物を生成して磁気特性を劣化させるため、０〜０．００７ｗｔ％（無添加の場合を含む）とする。
Ｎは、その含有量が多いとＡｌＮの析出量が多くなり、ＡｌＮが粗大化したとしても粒成長性を低下させて鉄損を増大させる。このためＮは０〜０．００５ｗｔ％（無添加の場合を含む）とする。
残部は実質的にＦｅからなり、不可避不純物元素等の少量の成分元素を含むことを妨げない。
【００１９】
本発明の製造方法では、上述した製造条件以外は特別な制約はなく、したがって、通常の製造条件を採用して構わない。すなわち、転炉で吹練した溶鋼を脱ガス処理して所定の成分に調整した後、スラブに鋳造し、このスラブを上述した条件で熱間圧延する。本発明では、熱延板焼鈍を実施しなくてもリジング発生の防止と仕上焼鈍後の低鉄損化を達成できる。次いで、一回の冷間圧延若しくは中間焼鈍をはさんだ２回以上の冷間圧延により所定の板厚とした後に、仕上焼鈍を行う。
【００２０】
【実施例】
転炉吹錬および脱ガス処理を経て表２に示す組成の鋼を溶製し、これをスラブに鋳造し、このスラブを表３に示す条件で板厚２．０ｍｍまで熱間圧延した。次いで、この熱延板を酸洗した後、板厚０．５ｍｍまで冷間圧延し、さらに２５％Ｈ2−７５％Ｎ2雰囲気中で９００℃×１分間の仕上焼鈍を行った。このようにして得られた各鋼板の鉄損Ｗ15/50を２５ｃｍエプスタイン試験片を用いて測定するとともに、仕上焼鈍後のリジングの有無を調べた。その結果を、表３に併せて示す。
表３によれば、本発明例で製造された無方向性電磁鋼板はリジングの発生がない優れた表面性状を有し、しかも仕上焼鈍後の鉄損も十分に低減されていることが判る。
【００２１】
【表２】
【表３】
【発明の効果】
以上述べたように本発明法によれば、リジングの発生がない優れた表面性状を有し、且つ仕上焼鈍後の鉄損が低い無方向性電磁鋼板を安定して製造することができる。
【図面の簡単な説明】
【図１】粗圧延後の加熱処理における加熱温度と仕上焼鈍後の鉄損およびリジング発生との関係を示すグラフ
【図２】粗圧延後の加熱処理における加熱保持時間と仕上焼鈍後の鉄損およびリジング発生との関係を示すグラフ[0001]
[Technical field to which the invention belongs]
The present invention relates to a method for producing a non-oriented electrical steel sheet having excellent surface properties with no ridging and low iron loss.
[0002]
[Prior art]
Non-oriented electrical steel sheets, when the Si content is 1.5 wt% or more, are liable to cause surface quality defects called ridging in the product after cold rolling, and usually the Si content is 1.5 wt% or more. Hot rolled sheet annealing is performed in the manufacture of non-oriented electrical steel sheets.
[0003]
[Problems to be solved by the invention]
However, since hot-rolled sheet annealing causes a significant increase in manufacturing cost, as an alternative method, techniques such as winding a hot-rolled coil at a high temperature and self-annealing the hot-rolled sheet have been studied. In order to perform such self-annealing of a hot-rolled sheet, it is necessary to finish the hot-rolled sheet at a high temperature in order to ensure the temperature after coil winding, and for that purpose, it is necessary to increase the slab heating temperature. However, when the slab heating temperature is increased in this manner, the sulfide and nitride in the steel are re-dissolved, so that there is a problem that the grain growth property at the time of finish annealing is lowered and the magnetic properties are lowered.
[0004]
Accordingly, an object of the present invention is to solve such a conventional problem, and to produce a non-oriented electrical steel sheet having excellent surface properties that do not generate ridging even if hot-rolled sheet annealing is not performed and low iron loss. Is to provide.
[0005]
[Means for Solving the Problems]
The present inventors have examined the production conditions of a non-oriented electrical steel sheet that can appropriately avoid ridging without performing hot-rolled sheet annealing and also have excellent iron loss characteristics. Obtained knowledge.
(1) C: 0 to 0.005 wt%, P: 0 to 0.1 wt%, N: 0 to 0.005 wt%, Si: 1.5 to 4.0 wt%, Mn: 0.05 to 1.0 wt% %, Sol. When manufacturing a non-oriented electrical steel sheet using a slab having a composition of Al: 0.1 to 1.0 wt%, S: 0 to 0.007 wt%, and the balance substantially consisting of Fe, hot-rolled sheet annealing is performed. In order to reduce the iron loss after finish annealing without the need, the slab heating temperature needs to be 1150 ° C. or lower, which is the low temperature heating region.
[0006]
(2) Also, by heating the slab at a low temperature as in (1) above, fine precipitates are not deposited after hot rolling, and the recrystallization temperature of the hot-rolled sheet is lowered.
(3) However, in such low temperature heating of the slab, it is extremely difficult to ensure a predetermined coiling temperature unless reheating to a temperature range of 1000 ° C. or higher after rough rolling.
(4) On the other hand, when the reheating temperature after rough rolling exceeds 1150 ° C., the precipitates are re-dissolved, so the iron loss after finish annealing decreases.
[0007]
(5) For ridging, it is important to recrystallize the structure before the finish rolling. For this purpose, in order to give the strain energy necessary for recrystallization in the rough rolling stage, the rolling reduction is 60% in rough rolling. It is effective to perform the above-described reduction and then to perform a heat treatment at 1000 ° C. or more and a holding time of 2 seconds or more.
(6) However, when this heating and holding time exceeds 10 seconds, re-dissolution of precipitates occurs in part, and the final iron loss characteristics deteriorate, so the heating and holding time is set to 10 seconds or less, It is necessary to perform finish rolling.
(7) Furthermore, the hot-rolled sheet is recrystallized by winding the hot-rolled sheet at 650 ° C. or more, which effectively works to avoid ridging.
[0008]
The present invention has been made on the basis of such findings, and the features thereof are as follows: C: 0 to 0.005 wt%, P: 0 to 0.1 wt%, N: 0 to 0.005 wt%, Si: 1.5 -4.0 wt%, Mn: 0.05-1.0 wt%, Sol. A non-oriented electrical steel sheet after hot-rolling a slab having a composition comprising Al: 0.1 to 1.0 wt%, S: 0 to 0.007 wt%, the balance Fe and inevitable impurities , followed by cold rolling and finish annealing When the hot rolling is performed, the slab is heated to a temperature of 1150 ° C. or lower, and then rough-rolled at a rolling reduction of 60% or more with a roughing mill. A method for producing a non-oriented electrical steel sheet, comprising heating to a temperature of ˜1150 ° C. and performing a heat treatment for holding in this temperature range for 2 to 10 seconds, followed by finish rolling and winding at 650 ° C. or higher It is.
[0009]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, the details of the present invention will be described together with the reasons for limitation.
In the present invention, a slab having a specific component composition is used as a raw material, and when this is hot-rolled, the slab is heated to a temperature of 1150 ° C. or lower and then roughly rolled at a rolling reduction of 60% or more with a roughing mill. Subsequently, the rough rolled material is heated to 1000 to 1150 ° C. and subjected to heat treatment for 2 to 10 seconds in this temperature range, and then finish rolling is performed at 650 ° C. or higher.
[0010]
First, in order to investigate the influence of the slab heating temperature and the heating temperature (reheating temperature) in the heat treatment after rough rolling on the generation of ridging and the iron loss after finish annealing, the following tests were performed.
C: 0.0022 wt%, Si: 1.76 wt%, Mn: 0.29 wt%, P: 0.05 wt%, S: 0.0033 wt%, Sol. A steel having a composition of Al: 0.34 wt% and N: 0.0022 wt% was melted and cast to produce a slab. The slab was heated from room temperature to 1100 ° C. and 1200 ° C. and roughly rolled at a reduction rate of 70%, and then heated to a temperature of 900 to 1250 ° C. using a high-frequency heating device, and the temperature was raised to that temperature for 5 seconds. After performing the heat processing to hold | maintain, finish rolling was performed to plate | board thickness 2.0mm, and it wound up at 700 degreeC. Next, the hot-rolled sheet was pickled, cold-rolled to a sheet thickness of 0.5 mm, and further annealed at 900 ° C. for 1 minute in a 25% H 2 -75% N 2 atmosphere.
[0011]
FIG. 1 shows the iron loss of the steel sheet thus obtained and the presence or absence of ridging. According to this, regarding the iron loss, an excellent iron loss is obtained when the slab heating temperature is 1100 ° C. and the heating temperature in the heat treatment after rough rolling is 1150 ° C. or less. On the other hand, when the slab heating temperature is 1200 ° C., the effect of reducing the iron loss by the heat treatment after rough rolling is not obtained at all. As a result of further investigation on the slab heating temperature at which the iron loss reduction effect by the heat treatment after rough rolling was obtained, it was found that the upper limit of the slab heating temperature at which the iron loss reduction effect was obtained was approximately 1150 ° C. On the other hand, regarding the presence or absence of ridging when the slab heating temperature is 1100 ° C., it can be seen that ridging tends to decrease when the heating temperature after rough rolling is 1000 ° C. or higher.
For the above reasons, in the present invention, the slab heating temperature when heating the slab from room temperature is set to 1150 ° C. or less, and the heating temperature in the heat treatment after rough rolling is set to 1000 to 1150 ° C. However, when the slab heating temperature is less than 950 ° C., the hot rolling itself becomes difficult, so the lower limit of the slab heating temperature is preferably 950 ° C.
[0012]
Next, in order to investigate the influence of the heat holding time in the heat treatment after rough rolling on the generation of ridging and the iron loss after finish annealing, the following tests were performed.
C: 0.0030 wt%, Si: 1.79 wt%, Mn: 0.34 wt%, P: 0.04 wt%, S: 0.0028 wt%, Sol. A steel having a composition of Al: 0.32 wt% and N: 0.0021 wt% was melted and cast to produce a slab. The slab was heated from room temperature to 1100 ° C. and roughly rolled at a reduction rate of 70%, and subsequently heated to 1150 ° C. using a high-frequency heating device and subjected to heat treatment for 1 to 20 seconds. Thereafter, finish rolling was performed to a plate thickness of 2.0 mm, and the product was wound at 700 ° C. Next, the hot-rolled sheet was pickled, cold-rolled to a sheet thickness of 0.5 mm, and further annealed at 900 ° C. for 1 minute in a 25% H 2 -75% N 2 atmosphere.
[0013]
FIG. 2 shows the iron loss of the steel sheet thus obtained and the presence or absence of ridging. According to this, it can be seen that if the holding time in the heat treatment after rough rolling exceeds 10 seconds, the iron loss tends to deteriorate, whereas if the holding time is less than 2 seconds, ridging tends to occur.
For the above reasons, in the present invention, the holding time at 1000 to 1150 ° C. in the heat treatment after rough rolling is set to 2 to 10 seconds, and then finish rolling is performed.
[0014]
Furthermore, in order to investigate the influence of the rolling reduction of rough rolling on the generation of ridging, the following tests were conducted.
A slab having the same composition as the slab used in the test of FIG. 2 was heated to 1100 ° C. and rough-rolled at a rolling reduction of 40 to 90%. Subsequently, this rough rolled material is heated to 1150 ° C. using a high-frequency heating device, subjected to heat treatment for 5 seconds, and then finish-rolled to a thickness of 2.0 mm and wound at 700 ° C. I took it. Next, the hot-rolled sheet was pickled, cold-rolled to a sheet thickness of 0.5 mm, and further annealed at 900 ° C. for 1 minute in a 25% H 2 -75% N 2 atmosphere.
Table 1 shows the presence or absence of ridging after finish annealing for materials subjected to rough rolling at each rolling reduction, and it can be seen that ridging is avoided at a rolling reduction of 60% or more. For this reason, in this invention, the rolling reduction of rough rolling shall be 60% or more. However, when the rolling reduction of rough rolling exceeds 90%, hot rolling becomes impossible due to an increase in the load of the mill, and therefore the upper limit of the rolling reduction of rough rolling is preferably 90%.
[0015]
[Table 1]
Next, the reason for limiting the steel composition will be described.
Si is an effective element for increasing the specific resistance of a steel sheet. To obtain this effect, addition of 1.5 wt% or more is necessary. However, if it exceeds 4.0 wt%, the saturation magnetic flux density decreases. Magnetic flux density decreases. For this reason, Si is 1.5 to 4.0 wt%.
Al, like Si, is an effective element for increasing the specific resistance. When Al exceeds 1.0 wt%, the magnetic flux density decreases as the saturation magnetic flux density decreases. On the other hand, Sol. When Al is less than 0.1 wt%, AlN becomes finer and grain growth property is lowered. For this reason, Sol. Al is 0.1 to 1.0 wt%.
[0017]
C has a problem of magnetic aging, so 0 to 0.005 wt% (including the case of no addition).
Mn needs to be added in an amount of 0.05 wt% or more in order to prevent red hot brittleness during hot rolling, but if it exceeds 1.0 wt%, the magnetic flux density is lowered, so 0.05 to 1.0 wt% is set.
P is an effective element for improving the punchability of the steel sheet, but if added over 0.1 wt%, the steel sheet becomes brittle, so 0 to 0.1 wt% (including the case of no addition). .
[0018]
S forms 0 to 0.007 wt% (including the case of no addition) in order to generate fine precipitates and deteriorate the magnetic properties.
When the content of N is large, the amount of precipitated AlN increases, and even if AlN is coarsened, the grain growth is reduced and the iron loss is increased. Therefore, N is 0 to 0.005 wt% (including the case where no additive is added).
The balance is substantially made of Fe and does not prevent inclusion of a small amount of component elements such as inevitable impurity elements.
[0019]
In the manufacturing method of the present invention, there are no special restrictions other than the manufacturing conditions described above, and therefore normal manufacturing conditions may be adopted. That is, the molten steel blown in the converter is degassed and adjusted to a predetermined component, then cast into a slab, and the slab is hot-rolled under the above-described conditions. In the present invention, it is possible to prevent the occurrence of ridging and to reduce the iron loss after finish annealing without carrying out hot-rolled sheet annealing. Next, after a predetermined sheet thickness is obtained by two or more cold rollings with one cold rolling or intermediate annealing, finish annealing is performed.
[0020]
【Example】
Steel having the composition shown in Table 2 was melted through converter blowing and degassing treatment, cast into a slab, and this slab was hot-rolled to a thickness of 2.0 mm under the conditions shown in Table 3. Next, the hot-rolled sheet was pickled, cold-rolled to a sheet thickness of 0.5 mm, and further annealed at 900 ° C. for 1 minute in a 25% H 2 -75% N 2 atmosphere. The iron loss W15 / 50 of each steel plate thus obtained was measured using a 25 cm Epstein test piece, and the presence or absence of ridging after finish annealing was examined. The results are also shown in Table 3.
According to Table 3, it can be seen that the non-oriented electrical steel sheets produced in the examples of the present invention have excellent surface properties with no ridging, and the iron loss after finish annealing is sufficiently reduced.
[0021]
[Table 2]
[Table 3]
【The invention's effect】
As described above, according to the method of the present invention, a non-oriented electrical steel sheet having excellent surface properties free from ridging and having low iron loss after finish annealing can be stably produced.
[Brief description of the drawings]
FIG. 1 is a graph showing the relationship between the heating temperature in heat treatment after rough rolling and the iron loss and ridging generation after finish annealing. FIG. 2 is the heat holding time in the heat treatment after rough rolling and the iron loss after finish annealing. And graph showing the relationship with ridging
Claims (1)
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| Application Number | Priority Date | Filing Date | Title |
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| JP22727097A JP4207231B2 (en) | 1997-08-08 | 1997-08-08 | Method for producing non-oriented electrical steel sheet |
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| Application Number | Priority Date | Filing Date | Title |
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| JP22727097A JP4207231B2 (en) | 1997-08-08 | 1997-08-08 | Method for producing non-oriented electrical steel sheet |
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| JPH1161256A JPH1161256A (en) | 1999-03-05 |
| JP4207231B2 true JP4207231B2 (en) | 2009-01-14 |
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| JP22727097A Expired - Lifetime JP4207231B2 (en) | 1997-08-08 | 1997-08-08 | Method for producing non-oriented electrical steel sheet |
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| JP2013144825A (en) * | 2012-01-13 | 2013-07-25 | Nippon Steel & Sumitomo Metal Corp | Production method of nonoriented magnetic steel sheet |
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| Publication number | Priority date | Publication date | Assignee | Title |
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| JP2013144825A (en) * | 2012-01-13 | 2013-07-25 | Nippon Steel & Sumitomo Metal Corp | Production method of nonoriented magnetic steel sheet |
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