JP2735898B2 - Method for producing unidirectional silicon steel sheet with uniform magnetic properties - Google Patents

Description

【発明の詳細な説明】 （産業上の利用分野） この発明は、優れた磁気特性を有する一方向性けい素
鋼板の製造方法に関し、特にスラブ加熱方法に工夫を加
えることによって板幅方向における磁気特性の均一化を
図ろうとするものである。Description: TECHNICAL FIELD The present invention relates to a method for producing a unidirectional silicon steel sheet having excellent magnetic properties, and more particularly, to a method for heating a slab by improving the slab heating method. It is intended to make the characteristics uniform.

（従来の技術） 一方向性けい素鋼板は、主として変圧器およびその他
の電気機器の鉄心材料として、いわゆる積み鉄芯、また
は巻鉄芯として使用されるもので、磁束密度や鉄損値等
の磁気特性が優れていることが基本的に重要である。該
鋼板の表面には、通常電気的絶縁被膜が被成され、鋼板
を積層して使用する場合に板の層間を電気的に絶縁し、
渦電流損失を低減する方策がとられている。(Prior art) Unidirectional silicon steel sheet is mainly used as a core material of transformers and other electric equipment, so-called piled iron core or wound iron core. It is basically important that the magnetic properties are excellent. On the surface of the steel sheet, an electrical insulating coating is usually formed, and when the steel sheets are stacked and used, electrically insulate between layers of the sheet,
Measures have been taken to reduce eddy current losses.

しかしながら鋼板表面に疵があって平滑性に劣る場合
は、商品価値が低下するのみならず、占積率が低下し、
また鉄芯組立時の締め付けによって絶縁性も低下し、局
所的な発熱を起こし、変圧器事故の原因になるため、変
圧器製造業者は鋼板表面の平滑性について極度に注意を
払っている。However, when the surface of the steel sheet has flaws and is inferior in smoothness, not only does the commercial value decrease, the space factor decreases,
In addition, transformer manufacturers pay extreme attention to the smoothness of the steel sheet surface because the insulation property is reduced due to tightening at the time of assembling the iron core, causing local heat generation and causing a transformer accident.

一方向性けい素鋼板の製造において特に重要な工程
は、いわゆる最終仕上焼鈍段階で１次再結晶粒から｛11
0｝＜001＞方位の結晶粒に２次再結晶させることにあ
る。このような２次再結晶を効果的な促進させるために
は、１次再結晶粒の正常成長を抑制するインヒビターと
称する分散相を必要とする。A particularly important step in the production of a grain-oriented silicon steel sheet is the so-called final finish annealing step, in which the primary recrystallized grains are reduced by 11%.
The purpose of the present invention is to recrystallize the crystal grains in the 0｝ <001> direction. In order to effectively promote such secondary recrystallization, a dispersed phase called an inhibitor that suppresses normal growth of primary recrystallized grains is required.

かかるインヒビターには、MnS,MnSe,AlNおよびVNのよ
うな硫化物や窒化物等の、鋼中への溶解度が極めて小さ
い物質が主に用いられている。さらに、Sb,Sn,As,Pb,G
e,Cu及びMo等の粒界偏析型元素もインヒビターとして利
用されている。これらインヒビターの効果は、最終仕上
焼鈍前までに均一かつ適正なサイズにインヒビターを分
散させることによって達成される。そのためには、熱間
圧延前にスラブを高温加熱して、インヒビター元素を十
分に固溶させておき、熱間圧延から２次再結晶までの工
程にて析出分散状態を制御すること、さらに１回または
２回以上の冷間圧延および１回または２回以上の焼鈍に
よって得られる１次再結晶粒組織は、板厚方向全体にわ
たって適当な大きさの結晶粒が均一な大きさで分布して
いることが肝要である。For such inhibitors, substances having extremely low solubility in steel, such as sulfides and nitrides such as MnS, MnSe, AlN and VN, are mainly used. Furthermore, Sb, Sn, As, Pb, G
Grain boundary segregation type elements such as e, Cu and Mo are also used as inhibitors. The effect of these inhibitors is achieved by dispersing the inhibitors in a uniform and appropriate size prior to final finish annealing. For this purpose, the slab is heated to a high temperature before hot rolling to sufficiently dissolve the inhibitor element, and the precipitation and dispersion state is controlled in the steps from hot rolling to secondary recrystallization. The primary recrystallized grain structure obtained by cold rolling twice or more times and annealing once or more times has a uniform size distribution of crystal grains of an appropriate size throughout the thickness direction. Is important.

従来の一方向性けい素鋼板の製造方法においては、厚
さ100〜300mmのスラブを1250℃以上の温度に長時間保持
してインヒビターを固溶させた後、熱間圧延を施し、つ
いで熱延板を１回ないし中間焼鈍をはさむ２回以上の冷
間圧延によって最終板厚とし、脱炭焼鈍を施したのち、
鋼板表面に焼鈍分離剤を塗布し、その後２次再結晶およ
び純化を目的として最終仕上げ焼鈍を行うのが一般的で
ある。In a conventional method for manufacturing a unidirectional silicon steel sheet, a slab having a thickness of 100 to 300 mm is kept at a temperature of 1250 ° C. or higher for a long time to form a solid solution of the inhibitor, then hot-rolled, and then hot-rolled. After the sheet has been subjected to decarburizing annealing after the sheet has been subjected to cold rolling once or twice or more with intermediate annealing to obtain a final sheet thickness,
Generally, an annealing separator is applied to the surface of a steel sheet, and then a final finish annealing is performed for the purpose of secondary recrystallization and purification.

ところで、近年の鉄鋼製造工程においては、スラブ製
造の大半が造塊・分塊圧延法から連続鋳造法に移行して
いる。かかる連続鋳造法を一方向性けい素鋼板の製造に
単純に適用した場合には、分塊圧延による結晶組織の微
細化工程が省略されるため、結晶組織は連続鋳造法固有
の急冷凝固による柱状晶粒となる。この柱状晶粒は前記
スラブ加熱で異常成長を起こしやすく、熱間圧延後に粗
大な伸粒として残る。この粗大な延伸粒は冷間圧延およ
び焼鈍を経た後も再結晶しにくく、インヒビターによる
抑制力効果が十分であっても、延伸粒部分での最終仕上
げ焼鈍による｛110｝＜001＞方位の２次再結晶は、不完
全となって、いわゆる帯状細粒組織となり、磁気特性の
劣化を招く。By the way, in the recent steel manufacturing process, most of the slab manufacturing has shifted from the ingot-bulking and rolling method to the continuous casting method. When such a continuous casting method is simply applied to the production of a unidirectional silicon steel sheet, the step of refining the crystal structure by slab rolling is omitted. It becomes crystal grains. The columnar grains are likely to undergo abnormal growth by the slab heating, and remain as coarsely elongated grains after hot rolling. The coarse stretched grains are unlikely to be recrystallized even after cold rolling and annealing, and even if the inhibitory effect of the inhibitor is sufficient, the {110} <001> orientation of the final finish annealing in the stretched grain portion is not sufficient. The next recrystallization becomes incomplete and becomes a so-called band-like fine grain structure, which causes deterioration of magnetic properties.

製品磁気特性は通常JISに基づき、幅30×長さ280mmの
試片約500g（0.30mm厚で24または28枚）をコイル幅方向
に採取したもので行われる。仮に前記試片中に幅30mm程
度の帯状細粒が１〜２条混入しても大幅な磁気特性の劣
化が起こらず、したがって不良部の存在を知ることは難
しい。しかも最終仕上焼鈍において、２次再結晶、純化
およびフォルステライト被膜の形成を同一工程で行うた
め、一旦製品化したものは外見上からも区別はできず、
不良部は容易に除去できない。特に通常の製品コイル幅
約1000mmを50mmまたは100mm程度の板幅に切断して巻鉄
芯用材とする場合には、帯状細粒がスリット板幅全体に
占める割合が極端に増加して鉄芯の磁気特性を著しく悪
化させるので、変圧器製造時にはとくに注意を払ってい
る。The product magnetic properties are usually based on JIS, and are obtained by sampling about 500 g (24 or 28 0.30 mm thick) specimens of 30 x 280 mm length in the coil width direction. Even if one or two strips of a width of about 30 mm are mixed in the test piece, no significant deterioration in magnetic characteristics occurs, and it is difficult to know the existence of a defective portion. Moreover, in the final finish annealing, secondary recrystallization, purification, and formation of the forsterite film are performed in the same process, so that once commercialized, it cannot be distinguished from the appearance,
Defective parts cannot be easily removed. In particular, when the normal product coil width of about 1000 mm is cut into a plate width of about 50 mm or 100 mm to be used as a core material, the proportion of strip-shaped fine grains in the entire slit Particular care has been taken in the manufacture of transformers, as they significantly degrade magnetic properties.

一般的にインヒビターの固溶は、高温かつ長時間にす
るほど完全状態に近づくが、その反面スラブ結晶粒の粗
大化が進行することはよく知られている。そのため、両
者の関係をうまく両立させることを狙った方策、例えば
低温鋳造あるいは溶鋼の電磁的撹拌によって鋳造スラブ
組織を微細化する方法、鋳造後スラブに予め歪を加えて
粗大な柱状晶を破壊しておき、スラブ加熱時に再結晶さ
せる方法またはスラブ加熱時の急速昇温により特定の結
晶粒の成長を抑制する方法等が既に提案されている。と
ころが、それらいずれの方策もスラブ加熱温度が極めて
高い領域では効果が不十分な問題が残っていた。Generally, the solid solution of the inhibitor approaches a complete state as the temperature and the temperature are increased for a long time, but it is well known that the slab crystal grains are coarsened. Therefore, measures aimed at achieving a good balance between the two, such as a method of refining the structure of the cast slab by low-temperature casting or electromagnetic stirring of molten steel, pre-strain the slab after casting to destroy coarse columnar crystals In addition, a method of recrystallization at the time of slab heating or a method of suppressing the growth of specific crystal grains by rapidly increasing the temperature at the time of slab heating have already been proposed. However, any of these measures still has a problem that the effect is insufficient in a region where the slab heating temperature is extremely high.

帯状細粒の防止策として特公昭54−27820号、特公昭5
0−37009号および特開昭62−130217号各公報には、それ
ぞれ連続鋳造スラブを加熱固溶する前に予め５〜50％、
30〜60％または10〜50％の圧延を施した後、1260〜1420
℃に再加熱し、最終の熱間圧延を行う方法が提案されて
いる。これらの方法は連鋳スラブに予め歪を加えておく
ことによりスラブ加熱で再結晶させ、結晶粒粗大化を抑
えようとするものである。しかしながら、通常連鋳スラ
ブには中心部近傍に濃厚偏析帯が存在し、その濃厚偏析
帯におけるインヒビターも固溶するには1380℃以上の高
温域でのかなり長い保持を要する。そのためスラブ結晶
粒は表層部から中心部まで著しく粗大化し、粗大結晶粒
に起因した帯状細粒が発生し、期待した磁気特性改善効
果は得られない問題があった。一方、スラブを比較的に
低温・短時間の結晶粒を粗大化させない条件で加熱した
場合には、濃厚偏析部のインヒビターに未固溶部分を生
じ、熱間圧延工程での分散状態が不均一となって抑制力
を強められず、磁気特性はむしろ大幅に劣化してしまう
問題があった。No. 54-27820, No. 5 as a measure to prevent zonal fines
No. 0-37009 and JP-A-62-130217, each of the continuous cast slabs is preliminarily 5 to 50% before solid solution heating.
After rolling 30-60% or 10-50%, 1260-1420
A method has been proposed in which the steel sheet is reheated to ° C. and subjected to final hot rolling. In these methods, a strain is applied to the continuous casting slab in advance so that the slab is recrystallized by heating to suppress coarsening of crystal grains. However, a continuous segregated slab usually has a thick segregation zone near the center, and the inhibitor in the thick segregation zone needs to be maintained at a high temperature of 1380 ° C. or more for a long time to form a solid solution. Therefore, the slab crystal grains are remarkably coarsened from the surface layer portion to the center portion, and band-like fine grains are generated due to the coarse crystal grains, and there is a problem that an expected effect of improving magnetic properties cannot be obtained. On the other hand, if the slab is heated at a relatively low temperature and for a short time under conditions that do not coarsen the crystal grains, an undissolved portion will be formed in the inhibitor in the dense segregation area, and the dispersion state in the hot rolling process will be uneven. As a result, there is a problem that the suppressing power cannot be strengthened, and the magnetic characteristics are rather deteriorated.

なおスラブを予め圧延する技術、すなわち鋼塊法にお
ける分塊工程に相当する技術は、連続鋳造法本来の目的
からみても合理的な方法とは言えない。The technique of rolling the slab in advance, that is, the technique corresponding to the ingot slab in the steel ingot method is not a reasonable method from the original purpose of the continuous casting method.

また特公昭56−18654号公報には、1260℃以上のスラ
ブ加熱に際し、1250〜1310℃までの温度範囲を平均昇温
速度150℃/h以上で加熱する方法が提案されている。こ
の方法は、スラブ加熱温度1370℃以下の条件では結晶粒
粗大化の抑制効果をあらわすが、概ね1380℃以上の高温
側において粒成長抑制効果が急激に弱まり、1400℃以上
では著しい表層の酸化と結晶粒の粗大化とが起こり、所
期した磁気特性や表層疵のない鋼板は得られないところ
に問題が残る。Japanese Patent Publication No. 56-18654 proposes a method of heating a slab at a temperature of 1260 ° C. or higher at an average heating rate of 150 ° C./h or more in a temperature range of 1250 to 1310 ° C. This method shows the effect of suppressing grain coarsening under the conditions of slab heating temperature of 1370 ° C or less, but the effect of suppressing grain growth is abruptly reduced at the high temperature side of about 1380 ° C or more, and significant surface oxidation and oxidation occurs at 1400 ° C or more. The crystal grains become coarse, and a problem remains where a steel sheet having the desired magnetic properties and no surface defects can not be obtained.

特開昭63−109115号公報には、スラブ中心温度が1350
℃以上になるように加熱し、この加熱に際して表面温度
1420〜1495℃で５〜60分保持するとともに、表面温度が
1320℃以上において1420〜1495℃に達するまで８℃/min
以上で急速昇温して結晶粒の粗大化を抑制する方法が提
案されている。この方法は、スラブ温度が従来のガス加
熱炉のみの方式より著しく高く、かつ保持時間が比較的
短い。しかしながら、このような高温領域では顕著な粒
成長が起こり、製品に帯状細粒が発生する。また、この
ような高温領域では著しい表面酸化や粒界の選択酸化に
より、製品価値がなくなるほどの穴や表面疵が多発する
ことの不利があった。JP-A-63-109115 discloses that the slab center temperature is 1350
Heat to a temperature of at least ℃
Hold at 1420 to 1495 ° C for 5 to 60 minutes, and when the surface temperature
8 ° C / min until the temperature reaches 1420 to 1495 ° C above 1320 ° C
As described above, a method has been proposed in which the temperature is rapidly increased to suppress coarsening of crystal grains. In this method, the slab temperature is significantly higher than that of the conventional gas heating furnace alone, and the holding time is relatively short. However, in such a high temperature region, remarkable grain growth occurs, and band-like fine grains are generated in the product. Further, in such a high-temperature region, there is a disadvantage that holes and surface flaws are generated so much that the product value is lost due to remarkable surface oxidation and selective oxidation of grain boundaries.

特開昭62−103322号公報は、誘導加熱炉においてスラ
ブ中心温度を1300〜1400℃に加熱保持する際、表皮効果
によるオーバーヒートを防ぎ、均一加熱をめざして周波
数を50〜200Hzに変えるもので、インヒビターの完全固
溶について触れるところはない。JP-A-62-103322 discloses that when the slab center temperature is maintained at 1300 to 1400 ° C. in an induction heating furnace, overheating due to a skin effect is prevented, and the frequency is changed to 50 to 200 Hz for uniform heating. There is no mention of the complete solid solution of the inhibitor.

さらに特開昭62−10214号公報には鋼板表面と内部の
温度差を利用して効率よく加熱する方法について、特開
昭62−100128号公報にはスラブの中心温度を1300〜1450
℃に加熱し、後工程の粗圧延段階で生じる線状ヘゲごと
きの表面欠陥を防止するために粗圧延開始温度を規制す
ることについて、それぞれ記載があるが、帯状細粒の発
生を防止することに関しての記載はない。Further, Japanese Patent Application Laid-Open No. 62-10214 discloses a method of efficiently heating by utilizing a temperature difference between the surface and the inside of a steel sheet.
C. and regulate the rough rolling start temperature in order to prevent surface defects such as linear barges generated in the rough rolling stage in the subsequent process. There is no statement about this.

（発明が解決しようとする課題） この発明は、上述の問題点を解決することを目的と
し、とくに鉄芯材料に対する需要家の要請に応え、表面
疵がなく、しかも均一でかつ良好な磁気特性を有する鉄
芯用材料を安定して製造する方法を提供するものであ
る。(Problems to be Solved by the Invention) An object of the present invention is to solve the above-mentioned problems, and in particular, to meet the demands of customers for iron core materials, to have no surface flaws, and to have uniform and good magnetic properties. It is intended to provide a method for stably producing an iron core material having the following.

（課題を解決するための手段） 製品の磁気特性および表面外観がともにすぐれた一方
向性けい素鋼板を製造するために、発明者らは誘導式加
熱炉を用いスラブ加熱方法を種々検討したところ、昇温
パターン、加熱温度および炉内雰囲気を改善し、目標を
達成することができた。(Means for Solving the Problems) In order to produce a unidirectional silicon steel sheet having excellent magnetic properties and surface appearance of the product, the inventors examined various slab heating methods using an induction heating furnace. The target was achieved by improving the heating pattern, heating temperature and atmosphere in the furnace.

すなわちこの発明は、含けい素鋼スラブを加熱した
後、熱間圧延を施し、その後１回または中間焼鈍をはさ
む２回以上の冷間圧延を施して最終板厚に仕上げたの
ち、脱炭焼鈍を施し、次いで鋼板表面に焼鈍分離剤を塗
布してから、仕上げ焼鈍を施す一連の工程によって一方
向性けい素鋼板を製造するに当たり、上記のスラブ加熱
に際し、保護ガス雰囲気中でスラブを粒界偏析の少なく
とも一部が溶融する温度域に達するまで加熱し、その後
1380〜1440℃の温度域に５〜60min保持すること特徴と
する磁気特性の均一な一方向性けい素鋼板の製造方法で
ある。That is, the present invention provides a method of heating a silicon-containing steel slab, then performing hot rolling, and then performing one or two or more cold rolling operations including intermediate annealing to finish the final sheet thickness, and then decarburizing annealing. And then apply an annealing separator to the surface of the steel sheet, and then produce a unidirectional silicon steel sheet by a series of steps of finish annealing.When heating the slab, the slab is grain-bounded in a protective gas atmosphere. Heat until reaching the temperature range where at least part of the segregation melts, then
This is a method for producing a unidirectional silicon steel sheet having uniform magnetic properties, which is maintained in a temperature range of 1380 to 1440 ° C. for 5 to 60 minutes.

なおスラブ温度が低い場合は、予めガス燃焼型加熱炉
で1000〜1300℃に加熱した後、誘導加熱炉に装入して加
熱することが好ましい。When the slab temperature is low, it is preferable that the slab be heated to 1000 to 1300 ° C. in a gas-fired heating furnace before being charged into an induction heating furnace and heated.

（作 用） 発明者らは一方向性けい素鋼板用の連鋳スラブから帯
状細粒のない均一にして磁気特性のすぐれた製品を得る
ためのスラブ加熱方法に関して鋭意研究し、スラブ加熱
の温度と保持時間とが帯状細粒および表面疵の発生に深
い関係のあることを見いだした。(Operation) The inventors have conducted intensive research on a slab heating method for obtaining a uniform and excellent magnetic property product from a continuous cast slab for a grain-oriented silicon steel sheet without band-like fine grains. And retention time were found to be closely related to the occurrence of band-like fine grains and surface flaws.

次に上記知見を得るに至った実験結果について詳細に
説明する。Next, the experimental results that led to the above findings will be described in detail.

第１図は、C:0.035wt％（以下単に％で示す）、Si:3.
35％、Mn:0.075％およびS:0.018％を含み残部実質的にF
eからなる、厚さ210mmの連鋳スラブを徐冷後、該スラブ
から210×200×200mmの試片を切り出し、小型誘導式加
熱炉にて酸素濃度3000ppmの保護ガス中で平均10℃/min
の昇温速度で所定温度まで加熱し、結晶粒径と加熱温度
および保持時間との関係について調査した結果を示す。Fig. 1 shows C: 0.035wt% (hereinafter simply indicated as%), Si: 3.
35%, Mn: 0.075% and S: 0.018%, the balance being substantially F
e, after gradually cooling a continuous cast slab having a thickness of 210 mm, cut out a sample of 210 × 200 × 200 mm from the slab, average 10 ° C. / min in a protective gas having an oxygen concentration of 3000 ppm in a small induction heating furnace.
4 shows the results of investigation on the relationship between the crystal grain size, the heating temperature, and the holding time by heating to a predetermined temperature at a heating rate of.

同図から、1430℃以下の温度域においては加熱温度が
高く、または保持時間が長くなるほど結晶粒は粗大化
し、昇温速度10℃/minのような急速昇温を行った場合で
も結晶粒の粗大化はまぬがれないことがわかる。ところ
が1450℃以上の温度域では、従来の知見と異なって長時
間保持しても結晶粒の粗大化は抑制されていることが新
たに判明した。なお発明者らは、スラブ結晶粒径が20mm
以下であれば、熱間圧延、冷間圧延および焼鈍工程にお
いて微細組織となり、製品板に帯状細粒が発生しないこ
とを予め確認し、この実験を行った。From the figure, it can be seen that in the temperature range of 1430 ° C or lower, the heating temperature is higher or the holding time is longer, the crystal grains become coarser, and even when the temperature is rapidly increased at a heating rate of 10 ° C / min. It can be seen that the coarsening is inevitable. However, it has been newly found that in the temperature range of 1450 ° C. or higher, unlike the conventional knowledge, the coarsening of the crystal grains is suppressed even if the temperature is maintained for a long time. Note that the inventors have found that the slab crystal grain size is 20 mm.
If it is below, it was confirmed in advance that a microstructure was formed in the hot rolling, cold rolling and annealing steps, and no band-like fine grains were generated on the product sheet, and this experiment was performed.

さらに第１図と同一成分スラブを同一の方法で加熱
し、2.5mm厚の熱延板とした後、公知の中間焼鈍をはさ
む２回の冷間圧延により0.30mm厚の製品とし、1m²当り
の表面疵の発生個数を調査した結果を、第２図に示す。
同図から、表面疵は高温そして長時間保持になるほど多
発することがわかる。Further to FIG. 1 and the same components slab heated in the same way, after a 2.5mm thick hot rolled sheet, a 0.30mm thick product by two cold rolling sandwiching a known intermediate annealing, 1 m ² per FIG. 2 shows the result of investigation of the number of surface flaws generated.
From the figure, it can be seen that surface flaws occur more frequently at higher temperatures and for longer periods of time.

すなわち、結晶粒粗大化の抑制には第１図に示した高
温域での加熱保持が有利であるが、この高温域で長時間
保持することは表面疵の発生回避の観点からは不利とな
ることがわかる。したがってスラブの高温域での加熱保
持は、短時間とすることが好ましい。In other words, heating and holding in a high temperature range shown in FIG. 1 are advantageous for suppressing the coarsening of crystal grains, but holding for a long time in this high temperature range is disadvantageous from the viewpoint of avoiding generation of surface flaws. You can see that. Therefore, the heating and holding of the slab in the high temperature range is preferably performed for a short time.

そこでインヒビターの完全固溶、スラブ結晶粒粗大化
の抑制、および表面疵防止を満足させるべく、さらにス
ラブ加熱方法について鋭意検討した。Therefore, in order to satisfy the complete solid solution of the inhibitor, the suppression of coarsening of the slab crystal grains, and the prevention of surface flaws, the slab heating method was further studied.

すなわちC:0.037％、Si:3.40％、Mn:0.072％およびS:
0.017％を含み残部実質的にFeからなる、厚さ210mmの連
鋳スラブを徐冷した後、210×200×200mm寸法の試験片
を切り出し、予め不活性ガス雰囲気中で1000℃に予熱
し、次いで周波数変化機能と試験片に保護冷却ガスを吹
き付ける機能とを備えた誘導加熱炉に装入し、次に示す
パターンａおよびｂで加熱した後抽出し、引続き冷却し
て得られた鋼板の結晶粒の成長度合を調査した。That is, C: 0.037%, Si: 3.40%, Mn: 0.072% and S:
After slowly cooling a continuous cast slab having a thickness of 210 mm containing 0.017% and consisting essentially of Fe, a test piece having a size of 210 × 200 × 200 mm was cut out and preheated to 1000 ° C. in an inert gas atmosphere in advance. Then, it was charged into an induction heating furnace having a frequency changing function and a function of spraying a protective cooling gas to the test piece, heated and extracted in the following patterns a and b, extracted, and subsequently cooled to obtain a crystal of a steel sheet. The degree of grain growth was investigated.

a:所定温度（1430℃）まで平均昇温速度10℃/minで加熱
し、５〜120分間保持するヒートパターンを実施。a: Heat pattern is performed by heating to a predetermined temperature (1430 ° C) at an average rate of 10 ° C / min and holding for 5 to 120 minutes.

b:所定の１次加熱温度（1445〜1480℃）まで平均昇温速
度10℃/minで加熱し、２次加熱は1420〜1430℃にて５〜
120分間保持するヒートパターンを実施。b: Heat up to the specified primary heating temperature (1445 to 1480 ° C) at an average heating rate of 10 ° C / min.
Implement a heat pattern to hold for 120 minutes.

第３図に、スラブ加熱温度および保持時間と最大結晶
粒径との関係を示す。FIG. 3 shows the relationship between the slab heating temperature and the holding time and the maximum crystal grain size.

同図から、最大結晶粒径を20mm以下に抑えられる条件
は、１次加熱温度を1445℃以上に加熱しかつ２次加熱の
保持時間を60分以内にとどめた場合に得られることがわ
かった。The figure shows that the condition that the maximum crystal grain size can be suppressed to 20 mm or less is obtained when the primary heating temperature is heated to 1445 ° C. or more and the secondary heating holding time is kept within 60 minutes. .

なお上記した成分組成になるけい素鋼スラブにおい
て、一旦1445℃以上に加熱することによって結晶粒粗大
化を抑制できる理由は明確になっていないが、次のこと
が推定される。Although it is not clear why the silicon steel slab having the above-mentioned composition can suppress the coarsening of grains by heating it to 1445 ° C. or higher, the following is presumed.

すなわち、連続鋳造されたスラブは通常マクロ的な偏
析（スラブを幅20mm、厚さ1mmで切出した試料の化学分
析によってわかる偏析）とミクロ的な偏析（顕微鏡で数
十倍〜数百倍に拡大して確認できる数ミクロン〜数十ミ
クロンオーダーの偏析で、以下ミクロ偏析と称する）と
が存在するが、特にミクロ偏析が集中する結晶粒界は結
晶粒内に比べて偏析量が多く、融点は低くなっている。In other words, continuously cast slabs are usually macro-segregated (separation that can be determined by chemical analysis of a sample cut out of a slab with a width of 20 mm and a thickness of 1 mm) and micro-segregation (enlarged by several tens to several hundred times with a microscope) (Separation of the order of several microns to several tens of microns that can be confirmed by the following, referred to as micro-segregation), but especially at the grain boundaries where micro-segregation is concentrated, the segregation amount is larger than in the crystal grains, and the melting point is higher. It is lower.

したがってスラブがある温度以上に加熱した場合、粒
界偏析の一部が優先的に溶け、この溶融した粒界偏析が
粒界移動を抑制し、すなわち結晶粒の粗大化を妨げる役
割を果すものと考えられる。さらにこの働きは、粒界偏
析が部分的に溶けていればよいと考えられる。Therefore, when the slab is heated to a certain temperature or higher, a part of the grain boundary segregation is preferentially melted, and the melted grain boundary segregation suppresses the movement of the grain boundary, that is, plays a role of preventing the coarsening of the crystal grains. Conceivable. Further, it is considered that this function only needs to partially melt the grain boundary segregation.

また、このような温度域に達する加熱を繰り返して行
うことも、当然有効な方法である。Repeated heating to reach such a temperature range is also an effective method.

ところで粒界偏析が溶け始める温度（溶融開始温度）
は、一般に鋼を組成する成分の種類およびその含有量で
変化するが、とくに鋼の組成が炭化物、窒化物等の析出
物またはこれらの複合析出物であるミクロ偏析を生成す
る成分系では、成分元素の種類およびその含有量のほ
か、鋳造後の熱履歴によっても析出物の析出状態が影響
を受けるため、溶融開始温度は変化する。By the way, the temperature at which grain boundary segregation begins to melt (melting start temperature)
In general, the composition of the steel varies depending on the type and content of the components, particularly in the case of a component system in which the composition of the steel generates microsegregation, which is a precipitate such as a carbide, a nitride, or a composite precipitate of these components, In addition to the type and content of the elements and the thermal history after casting, the precipitation state of the precipitates is affected, so that the melting start temperature changes.

したがって１次加熱温度の下限は、一義的に決めるこ
とが困難であり、例えばＣやSiを含有する場合はその含
有量に応じて溶融開始温度は次のとおりに変化する。Therefore, it is difficult to uniquely determine the lower limit of the primary heating temperature. For example, when C or Si is contained, the melting start temperature changes as follows according to the content.

C :0.01％当り３℃ Si:0.1％当り2.5℃ 因みに、前記第３図に示した実験に供した鋼の成分系
における溶融開始温度を実験にて求めたところ、1445℃
と、結晶粒粗大化を抑制し得る１次加熱温度の下限とな
った。C: 3 ° C. per 0.01% Si: 2.5 ° C. per 0.1% By comparison, the melting onset temperature in the steel component system used in the experiment shown in FIG.
And the lower limit of the primary heating temperature at which crystal grain coarsening can be suppressed.

さらにスラブの１次加熱温度は、第２図に示したよう
に、結晶粒抑制の観点よりも表面疵防止の観点から、14
70℃をこえないことが好ましい。Further, as shown in FIG. 2, the primary heating temperature of the slab is set at a lower value from the viewpoint of preventing surface flaws than that of suppressing crystal grains.
Preferably it does not exceed 70 ° C.

また第３図に結果を示した実験と同様の連鋳スラブ
を、次の条件で処理して磁気特性評価用の試験片に供し
た。すなわち前記と同様の方法でスラブを、１次加熱ま
たは２次加熱にて処理した後、板厚2.5mmまで熱間圧延
し、酸洗にてミルスケールを除いた後、１次冷間圧延で
0.72mmの中間厚としてから、水素中で950℃、２分間の
中間焼鈍を施した。ついで２次冷間圧延にて0.30mmの最
終板厚とした後、湿水素中で820℃、３分間の脱炭焼鈍
を施し、引続きMgOを主成分とする焼鈍分離剤を鋼板表
面に塗布して乾燥後、水素中で1180℃、５時間の最終仕
上げ焼鈍を施し、試験片とした。A continuous cast slab similar to that in the experiment shown in FIG. 3 was processed under the following conditions and used as a test piece for evaluating magnetic properties. That is, the slab is treated by primary heating or secondary heating in the same manner as described above, and then hot-rolled to a thickness of 2.5 mm, and the mill scale is removed by pickling, followed by primary cold rolling.
After an intermediate thickness of 0.72 mm, intermediate annealing was performed in hydrogen at 950 ° C. for 2 minutes. Next, after a final thickness of 0.30 mm by secondary cold rolling, decarburizing annealing was performed in wet hydrogen at 820 ° C. for 3 minutes, and then an annealing separator containing MgO as a main component was applied to the steel sheet surface. After drying, a final finish annealing was performed in hydrogen at 1180 ° C. for 5 hours to obtain a test piece.

第４図に、JISに準拠した磁気特性の測定を、30×280
mm試験片一枚づつについて行った結果を示す。なお２次
加熱におけるスラブ加熱温度は２次加熱温度を示す。Fig. 4 shows the measurement of magnetic characteristics in accordance with JIS,
The results obtained for each mm test piece are shown. The slab heating temperature in the secondary heating indicates the secondary heating temperature.

同図から、スラブ２次加熱にて得られた鋼板は、従来
の１次加熱によるものと比べ、磁気特性レベルが高く、
かつ磁気特性差の小さいものが得られた。なお、1450℃
あるいは1470℃でのスラブ１次加熱によるものは、２次
加熱と同程度の磁気特性が得られたが、前述のように表
面疵が発生し、製品価値が劣るものであった。From the figure, the steel sheet obtained by the secondary heating of the slab has a higher magnetic characteristic level than the steel sheet obtained by the conventional primary heating.
In addition, one having a small difference in magnetic characteristics was obtained. In addition, 1450 ℃
Alternatively, in the case of the slab primary heating at 1470 ° C., the same magnetic properties as those of the secondary heating were obtained, but as described above, surface flaws were generated and the product value was inferior.

また第５図に、上記の実験における、２次加熱を施し
た際の保持時間と磁気特性との関係について示す。FIG. 5 shows the relationship between the holding time and the magnetic properties when the secondary heating is performed in the above experiment.

同図から、良好な磁気特性を安定して得るには、1380
〜1440℃の温度域に５〜60分間保持する必要のあること
がわかる。加熱温度が1380℃未満であるか、または適性
温度域でも保持時間が５分間未満である場合には磁気特
性の劣化がみられるが、これはインヒビター未固溶部の
残存が原因であった。一方保持時間が60分間をこえる場
合の磁気特性の劣化は、すでに第３図にて示したよう
に、20mm以上のスラブ粒発生に起因する帯状細粒の出現
が原因であった。From the figure, it can be seen that 1380
It can be seen that it is necessary to maintain the temperature range of 域 1440 ° C. for 5 to 60 minutes. When the heating temperature is less than 1380 ° C. or the holding time is less than 5 minutes even in an appropriate temperature range, the magnetic properties are deteriorated, but this is due to the remaining undissolved portion of the inhibitor. On the other hand, when the holding time exceeds 60 minutes, the deterioration of the magnetic properties was caused by the appearance of band-like fine grains due to the generation of slab grains of 20 mm or more, as already shown in FIG.

以上に示した第１図〜第５図から、表面疵を防ぎ、か
つ優れた磁気特性を均一に得るためには、次の条件お
よびに従う必要のあることが判明した。From FIGS. 1 to 5 shown above, it was found that the following conditions and conditions had to be met in order to prevent surface flaws and to obtain excellent magnetic properties uniformly.

スラブの１次加熱は、粒界偏析の少なくとも一部が溶
融する温度域に達するまで行う。Primary heating of the slab is performed until the temperature reaches a temperature range in which at least a part of the grain boundary segregation is melted.

スラブの２次加熱は、1380〜1440℃の範囲内で保持時
間は５〜60分間の範囲とする。The secondary heating of the slab is performed in the range of 1380 to 1440 ° C. and the holding time is in the range of 5 to 60 minutes.

この発明の素材である含けい素鋼としては、従来公知
の成分組成のものいずれもが適合するが、代表組成を掲
げると次のとおりである。As the silicon-containing steel which is the material of the present invention, any of the conventionally known component compositions are suitable, and typical compositions are as follows.

C:0.01〜0.10％ Ｃは、熱間圧延、冷間圧延中の組織の均一微細化のみ
ならず、ゴス方位の発達に有用な元素であり、少なくと
も0.01％以上の添加が好ましい。しかしながら0.10％を
超えて含有されるとかえってゴス方位に乱れが生じるの
で上限は0.10％程度が好ましい。C: 0.01 to 0.10% C is an element useful not only for uniform micronization of the structure during hot rolling and cold rolling, but also for development of the Goss orientation, and is preferably added at least 0.01% or more. However, if the content exceeds 0.10%, the Goss orientation is rather disturbed. Therefore, the upper limit is preferably about 0.10%.

Si:2.0〜4.5％ Siは、鋼板の比抵抗を高め鉄損の低減に有効に寄与す
るが、4.5％を上回ると冷延性が損なわれ、一方2.0％に
満たないと比抵抗が低下するだけでなく、２次再結晶・
純化のために行われる最終高温焼鈍中にα−γ変態によ
って結晶方位のランダム化を生じ、十分な鉄損改善効果
が得られないので、Si量は2.0〜4.5％程度とするのが好
ましい。Si: 2.0-4.5% Si increases the specific resistance of the steel sheet and effectively contributes to the reduction of iron loss. However, if it exceeds 4.5%, the cold-rolling property is impaired, whereas if it is less than 2.0%, the specific resistance only decreases. Not secondary recrystallization
Since the crystal orientation is randomized by the α-γ transformation during the final high-temperature annealing performed for the purification, and a sufficient iron loss improvement effect cannot be obtained, the Si content is preferably about 2.0 to 4.5%.

Mn:0.02〜0.12％ Mnは、熱間脆化を防止するため少なくとも0.02％程度
を必要とするが、あまりに多すぎると磁気特性を劣化さ
せるので上限は0.12％程度に定めるのが好ましい。Mn: 0.02 to 0.12% Mn needs to be at least about 0.02% in order to prevent hot embrittlement, but if it is too much, magnetic properties are degraded, so the upper limit is preferably set to about 0.12%.

インヒビターとしては、いわゆるMnS,MnSe系とAlN系
とがある。MnS,MnSe系の場合は、Se,Sのうちから選ばれ
る少なくとも１種:0.005〜0.06％ Se,Sはいずれも、方向性けい素鋼板の２次再結晶を制
御するインヒビターとして有力な元素である。抑制力確
保の観点からは、少なくとも0.005％程度を必要とする
が、0.06％を超えるとその効果が損なわれるので、その
下限、上限はそれぞれ0.01％,0.06％程度とするのが好
ましい。As inhibitors, there are so-called MnS, MnSe-based and AlN-based. In the case of MnS and MnSe, at least one selected from Se and S: 0.005 to 0.06% Se and S are all effective elements as inhibitors for controlling secondary recrystallization of grain-oriented silicon steel sheets. is there. From the viewpoint of securing the suppressing force, at least about 0.005% is required, but if it exceeds 0.06%, the effect is impaired. Therefore, the lower and upper limits are preferably set to about 0.01% and 0.06%, respectively.

AlN系の場合は、 Al:0.005〜0.10％,N:0.004〜0.015％ AlおよびＮの範囲についても、上述したMnS,MnSe系の
場合と同様な理由により、上記の範囲に定めた。ここに
上記したMnS,MnSe系およびAlN系はそれぞれ併用が可能
である。In the case of the AlN system, Al: 0.005 to 0.10%, N: 0.004 to 0.015% The range of Al and N is also set to the above range for the same reason as in the case of the MnS and MnSe systems described above. Here, the above-mentioned MnS, MnSe-based and AlN-based can be used in combination.

インヒビター成分としては上記したS,Se,Alの他、Cu,
Sn,Cr,Ge,Sb,Mo,Te,BiおよびＰなども有利に適合するの
で、それぞれ少量併せて含有させることもできる。ここ
に上記成分の好適添加範囲はそれぞれ、Cu,Sn,Cr:0.01
〜0.15％、Ge,Sb,Mo,Te,Bi:0.005〜0.1％、P:0.01〜0.2
％であり、これらの各インヒビター成分についても、単
独使用および複合使用いずれもが可能である。Inhibitor components include S, Se, Al, Cu,
Sn, Cr, Ge, Sb, Mo, Te, Bi, P, and the like are also advantageously used, so that a small amount of each of them can also be contained. Here, the preferred addition ranges of the above components are Cu, Sn, Cr: 0.01, respectively.
0.15%, Ge, Sb, Mo, Te, Bi: 0.005 to 0.1%, P: 0.01 to 0.2
%, And each of these inhibitor components can be used alone or in combination.

なおスラブは、連続鋳造されたものもしくはインゴッ
トより分塊されたものを対象とするが、連続鋳造された
後に、分塊再圧されたスラブも対象に含まれることはい
うまでもない。The slab is intended to be a continuously cast one or a lump from an ingot, but it goes without saying that a slab which has been continuously cast and then re-pumped is also included.

上記した成分条件を満たすスラブは、スラブ加熱でイ
ンヒビターを固溶する必要がある。通常インヒビターの
固溶処理には、1250℃以上で、しかも比較的低温では長
時間保持し、高温では短時間保持が利用されている。こ
の発生法ではスラブ加熱で結晶粒ざ粗大化して起こる弊
害を防ぐために：スラブを、粒界偏析の少なくとも一部
が溶融する超高温域に達するまで１次加熱した後、1380
〜1440℃の温度範囲で５分以上60分以内の２次加熱を行
う。A slab that satisfies the above-mentioned component conditions needs to form a solid solution of the inhibitor by slab heating. Usually, the solid solution treatment of the inhibitor is carried out at a temperature of 1250 ° C. or higher, at a relatively low temperature for a long time, and at a high temperature for a short time. In this generation method, in order to prevent the adverse effects caused by coarsening of grains by slab heating, the slab is first heated until reaching an ultra-high temperature region where at least a part of grain boundary segregation is melted, and then 1380
Secondary heating is performed in a temperature range of 1440C to 5 minutes or more and 60 minutes or less.

この２段階方式の加熱には、密閉構造にしやすく容易
に酸素濃度を下げられること、保護ガスによって酸化を
防止できること、温度制御が可能であることおよび高温
に効率よく加熱できること、等の理由から、誘導加熱炉
や抵抗加熱炉などの電気的加熱炉を用いるのが有利で、
この場合以下のことを考慮することが好ましい。すなわ
ち誘導加熱では表皮効果により周波数の違いで程度差は
あっても表層部分から加熱される。したがって１次加熱
前後においては周波数と投入電力の組み合わせを制御
し、１次加熱温度到達後にはさらにスラブ表面に保護冷
却ガスを吹き付けることによってオーバーヒートを防止
し、かつスラブ中心部分の高温化も達成する。The two-stage heating is performed in such a manner that the oxygen concentration can be easily reduced by easily forming a closed structure, the oxidation can be prevented by a protective gas, the temperature can be controlled, and the heating can be efficiently performed at a high temperature. It is advantageous to use an electric heating furnace such as an induction heating furnace or a resistance heating furnace,
In this case, it is preferable to consider the following. That is, in the induction heating, heating is performed from the surface layer portion even though there is a difference depending on the frequency due to the skin effect. Therefore, before and after the primary heating, the combination of the frequency and the input power is controlled, and after reaching the primary heating temperature, a protective cooling gas is further sprayed on the slab surface to prevent overheating and achieve a high temperature in the central portion of the slab. .

次に５〜60分の短時間加熱でインヒビターを固溶する
には、1380℃が下限であり、1445℃をこえると部分的に
液体を生じ、30分以上の長時間保持にて表面疵の発生や
スラブ形状の変化をまねくので上限を1440℃とした。Next, in order to form a solid solution of the inhibitor by heating for a short time of 5 to 60 minutes, the lower limit is 1380 ° C. The upper limit was set to 1440 ° C because it would cause generation and change in slab shape.

スラブ加熱でインヒビターを固溶処理後、1.4〜3.5mm
厚の熱延鋼帯とする。熱延鋼帯を酸洗後、１回の冷間圧
延または中間焼鈍をはさむ２回以上の冷間圧延とそれに
続く脱炭焼鈍、焼鈍分離剤塗布および仕上焼鈍の工程
は、公知の手段を用いることができる。1.4 ~ 3.5mm after solid solution treatment of inhibitor by slab heating
A thick hot-rolled steel strip. After pickling the hot-rolled steel strip, the steps of one or more cold rollings including one cold rolling or intermediate annealing, followed by decarburizing annealing, application of an annealing separator, and finish annealing use known means. be able to.

（実施例） 実施例１ C:0.035％、Si:3.05％、Mn:0.076％およびS:0.017％
を含有し残部実質的にFeよりなる、厚み210mmのスラブ
を、予めガス加熱炉にて1250℃で３時間加熱し、ついで
誘導加熱炉に装入し、周波数、投入電力量、保護ガス吹
き付け温度を変え、以下に示すＡ〜Ｅの５条件でインヒ
ビターを固溶処理した後、粗圧延機と仕上げ圧延機で2.
6mm厚の熱延鋼板とした。(Example) Example 1 C: 0.035%, Si: 3.05%, Mn: 0.076%, and S: 0.017%
A slab having a thickness of 210 mm and containing substantially the balance of Fe is heated in advance in a gas heating furnace at 1250 ° C. for 3 hours, then charged into an induction heating furnace, and subjected to frequency, input power, and protective gas spraying temperature. Was changed, and the inhibitor was subjected to solid solution treatment under the following five conditions A to E.
A hot-rolled steel sheet having a thickness of 6 mm was used.

A:昇温速度９℃/minで1430℃まで加熱し、20分間保持し
て抽出した。A: It was heated to 1430 ° C. at a heating rate of 9 ° C./min, held for 20 minutes and extracted.

B:昇温速度９℃/minで1475℃まで加熱し、30分間保持し
た後1420℃に下げて20分間保持して抽出した。B: Heated to 1475 ° C. at a heating rate of 9 ° C./min, held for 30 minutes, lowered to 1420 ° C., and held for 20 minutes for extraction.

C:昇温速度９℃/minで1460℃まで加熱し、３分間保持し
た後1420℃に下げて20分間保持して抽出した。C: Heated to 1460 ° C. at a heating rate of 9 ° C./min, held for 3 minutes, lowered to 1420 ° C., and held for 20 minutes for extraction.

D:昇温速度９℃/minで1450℃まで加熱し、３分間保持し
た後1380℃に下げて50分間保持して抽出した。D: Heated to 1450 ° C. at a heating rate of 9 ° C./min, kept for 3 minutes, lowered to 1380 ° C. and kept for 50 minutes for extraction.

E:昇温速度９℃/minで1450℃まで加熱し、３分間保持し
た後1340℃に下げて50分間保持して抽出した。E: Heated to 1450 ° C at a heating rate of 9 ° C / min, kept for 3 minutes, then lowered to 1340 ° C and kept for 50 minutes for extraction.

該熱延鋼板を酸洗し、１次冷間圧延で0.80mm厚とし、
ついで950℃で２分間の中間焼鈍を施し、２次冷間圧延
で0.35mmの最終厚みに仕上げた。引続き、湿水素中で82
0℃、３分間の脱炭焼鈍を施したのち、MgOを主成分とす
る焼鈍分離材を塗布し、水素中で1200℃、５時間の仕上
げ焼鈍を施して方向性電磁鋼板とした。得られた1030mm
幅のコイルから両エッジ15mmを除去した後、100mm幅の
サンプル10枚を切り出し磁気特性を測定し、また表面疵
の有無と２次再結晶状況を調査した。得られた結果を第
１表に示す。The hot-rolled steel sheet is pickled and first cold-rolled to a thickness of 0.80 mm,
Then, intermediate annealing was performed at 950 ° C. for 2 minutes, and a final thickness of 0.35 mm was obtained by secondary cold rolling. Subsequently, in wet hydrogen, 82
After decarburizing annealing at 0 ° C. for 3 minutes, an annealing separator containing MgO as a main component was applied, and subjected to finish annealing at 1200 ° C. for 5 hours in hydrogen to obtain a grain-oriented electrical steel sheet. 1030mm obtained
After removing both edges of 15 mm from the coil having a width, ten samples having a width of 100 mm were cut out, the magnetic properties were measured, and the presence or absence of surface flaws and the state of secondary recrystallization were investigated. Table 1 shows the obtained results.

第１表から明らかなように、この発明に従ったスラブ
加熱を実施することにより表面疵および帯状細粒を発生
させず、磁気特性の改善と均一化が図れる。 As is evident from Table 1, the slab heating according to the present invention does not generate surface flaws and band-like fine particles, and can improve and uniform the magnetic properties.

実施例２ C:0.045％、Si:3.35％、Mn:0.075％、Se:0.020％、S
b:0.030％、Mo:0.015％含有し残部実質的にFeよりな
る、240mm厚のスラブを、ガス加熱炉にて1250℃、３時
間予熱処理し、引続き誘導加熱炉に装入し、周波数、投
入電力量および保護ガス吹き付け温度を調節して、以下
に示すＦ〜Ｉの４条件でインヒビターを固溶処理した
後、2.0mm厚の熱延板とした。Example 2 C: 0.045%, Si: 3.35%, Mn: 0.075%, Se: 0.020%, S
b: 0.030%, Mo: 0.015%, slab of 240mm thickness consisting essentially of Fe and remaining at 1250 ° C for 3 hours in a gas heating furnace, and subsequently charged into an induction heating furnace, The inhibitor was subjected to solid solution treatment under the following four conditions F to I by adjusting the amount of electric power to be supplied and the protective gas spraying temperature, and then a hot-rolled sheet having a thickness of 2.0 mm was obtained.

F:昇温速度７℃/minで1450℃まで加熱し、30分間保持し
て抽出した。F: Heated to 1450 ° C at a heating rate of 7 ° C / min, held for 30 minutes and extracted.

G:昇温速度７℃/minで1450℃まで加熱して20分間保持し
た後1410℃に下げて100分間保持して抽出した。G: Heated to 1450 ° C at a heating rate of 7 ° C / min, held for 20 minutes, then lowered to 1410 ° C and held for 100 minutes for extraction.

H:昇温速度７℃/minで1450℃まで加熱して２分間保持し
た後1410℃に下げて100分間保持して抽出した。H: Heated to 1450 ° C. at a heating rate of 7 ° C./min and maintained for 2 minutes, then lowered to 1410 ° C. and maintained for 100 minutes for extraction.

I:昇温速度７℃/minで1350℃まで加熱し、90分間保持し
て抽出した。I: Heated to 1350 ° C at a heating rate of 7 ° C / min, held for 90 minutes to extract.

該熱延鋼板に950℃、１分間の熱延焼鈍を施し、１次
冷間圧延で0.60mm厚とし、次に水素中1000℃２分間の中
間焼鈍を施し、２次冷間圧延で0.23mm厚の最終板厚に仕
上げた。引続き湿水素中で830℃、３分間の脱炭焼鈍を
施したのち、MgOを主成分とする焼鈍分離剤を塗布し、
水素中で1200℃、５時間の仕上焼鈍を施して方向性けい
素鋼板とした。得られた1030mm幅のコイルから両エッジ
15mmを除去した後、100mm幅のサンプル10枚を取り出し
磁気特性、表面疵の有無および２次再結晶状況を調査し
た。得られた結果を第２表に示す。The hot-rolled steel sheet is subjected to hot-rolling annealing at 950 ° C. for 1 minute, to 0.60 mm thick by primary cold rolling, and then to intermediate annealing at 1000 ° C. for 2 minutes in hydrogen, and to 0.23 mm by secondary cold rolling. Finished to a thick final thickness. After decarburizing annealing at 830 ° C for 3 minutes in wet hydrogen, an annealing separator containing MgO as a main component was applied.
Finish annealing was performed in hydrogen at 1200 ° C. for 5 hours to obtain a grain-oriented silicon steel sheet. Both edges from the obtained 1030mm wide coil
After removing 15 mm, ten 100 mm wide samples were taken out, and the magnetic properties, the presence or absence of surface flaws, and the state of secondary recrystallization were investigated. Table 2 shows the obtained results.

第２表から明らなかように、この発明法に従えば、製
品厚みの薄みものでも効果のあることがわかる。 As is clear from Table 2, according to the method of the present invention, even a product having a small thickness is effective.

実施例３ C:0.065％、Si:3.15％、Mn:0.080％、Se:0.018％、S
b:0.025％、Al:0.025およびN:0.080％を含有し残部実質
的にFeよりなる、240mm厚のスラブに、ガス加熱炉で122
0℃、３時間の予熱処理を施し、引続き誘導加熱炉で周
波数、投入電力量および保護ガス吹き付け温度を適切に
選び、遂に示すＪ〜Ｎの５条件にてインヒビターを固溶
処理を実施した後、熱間圧延して1.8mm厚の熱延板とし
た。Example 3 C: 0.065%, Si: 3.15%, Mn: 0.080%, Se: 0.018%, S
b: A 240 mm thick slab containing 0.025%, Al: 0.025 and N: 0.080%, and substantially consisting of the balance of Fe
After performing a pre-heat treatment at 0 ° C. for 3 hours, and subsequently appropriately selecting a frequency, an input power amount and a protective gas spraying temperature in an induction heating furnace, and finally performing a solid solution treatment of the inhibitor under the five conditions J to N shown below. Then, hot rolling was performed to obtain a hot-rolled sheet having a thickness of 1.8 mm.

J:1430℃、30分間保持した後抽出した。J: Extracted after holding at 1430 ° C. for 30 minutes.

K:1次加熱として1475℃、２分間保持し、次いで２次加
熱として1420℃30分間保持した後抽出した。K: Maintained at 1475 ° C. for 2 minutes as primary heating, then kept at 1420 ° C. for 30 minutes as secondary heating, and then extracted.

L:1次加熱として1450℃、５分間保持し、次いで２次加
熱として1420℃30分間保持した後抽出した。L: Maintained at 1450 ° C. for 5 minutes as primary heating, and then maintained at 1420 ° C. for 30 minutes as secondary heating and then extracted.

M:1次加熱として1450℃、２分間保持し、次いで２次加
熱として1390℃30分間保持した後抽出した。M: Maintained at 1450 ° C. for 2 minutes as primary heating, and then maintained at 1390 ° C. for 30 minutes as secondary heating and extracted.

N:1340℃、30分間保持した後抽出した。N: Extracted after holding at 1340 ° C for 30 minutes.

該熱延鋼板に1050℃、１分間の焼鈍を施した後、冷間
圧延によって0.23mm厚に仕上げ、引続きと840℃で３分
間の湿水素中での脱炭焼鈍を施したのち、MgOを主成分
とする焼鈍分離剤を塗布し、水素中で1200℃、20時間の
仕上げ焼鈍を施して方向性けい素鋼板とした。得られた
1030mm幅のコイルから両エッジ15mmを除去した後、100m
m幅のサンプル10枚を切り出し、磁気特性、表面疵の有
無および２次再結晶状況を調査した。得られた結果を第
３表に示す。The hot-rolled steel sheet was annealed at 1050 ° C. for 1 minute, then finished by cold rolling to a thickness of 0.23 mm, and subsequently decarburized and annealed at 840 ° C. for 3 minutes in wet hydrogen. An annealing separator as a main component was applied and finish annealing was performed in hydrogen at 1200 ° C. for 20 hours to obtain a grain-oriented silicon steel sheet. Got
After removing both edges 15mm from the coil of 1030mm width, 100m
Ten samples of m width were cut out, and the magnetic properties, the presence or absence of surface flaws, and the state of secondary recrystallization were investigated. Table 3 shows the obtained results.

第３表から明らなかように、この発明法に従ってスラ
ブ加熱を実施することにより、冷延１回法においても表
面疵がなく、均一な磁気特性の製品が得られることがわ
かる。 As is clear from Table 3, it can be seen that by performing the slab heating in accordance with the method of the present invention, a product having no surface flaws and uniform magnetic properties can be obtained even in the single cold rolling method.

実施例４ C:0.073％、Si:3.20％、Mn:0.072％、Se:0.020％、A
l:0.030、およびN:0.080％を含有し残部実質的にFeより
なる、210mm厚スラブを、予めガス加熱炉で1200℃、３
時間加熱しておき、引続いて実施例１と同一条件でイン
ヒビターの固溶処理を行った後、熱間圧延にて3.0mm厚
の熱延鋼板とした。該熱延鋼板を１次冷間圧延で2.0mm
厚とし、次に水素中で1100℃、２分間の中間焼鈍を行
い、２次冷間圧延で0.30mmの最終板厚に仕上げた。引続
き湿水素中で840℃、３分間の脱炭焼鈍を施したのち、M
gOを主成分とする焼鈍分離剤を塗布し、水素中で1200
℃、20時間の仕上焼鈍を施して方向性けい素鋼板とし
た。得られた1030mm幅のコイルから両エッジ15mmを除去
した後、100mm幅のサンプルを10枚切り出し磁気特性、
表面疵の有無および２次再結晶状況を調査した。得られ
た結果を第４表に示す。Example 4 C: 0.073%, Si: 3.20%, Mn: 0.072%, Se: 0.020%, A
A 210 mm thick slab containing l: 0.030 and N: 0.080% and substantially consisting of the balance of Fe was previously heated to 1200 ° C. in a gas heating furnace at 3 ° C.
After heating for an hour and subsequently performing a solid solution treatment of the inhibitor under the same conditions as in Example 1, a hot-rolled steel sheet having a thickness of 3.0 mm was formed by hot rolling. The hot-rolled steel sheet is 2.0mm
Then, intermediate annealing was performed in hydrogen at 1100 ° C. for 2 minutes, and a second cold rolling was performed to obtain a final sheet thickness of 0.30 mm. After decarburizing annealing at 840 ° C for 3 minutes in wet hydrogen,
Apply an annealing separator containing gO as the main component, and in hydrogen
A finish annealing at 20 ° C. for 20 hours was performed to obtain a grain-oriented silicon steel sheet. After removing both edges 15mm from the obtained 1030mm width coil, 10 pieces of 100mm width samples were cut out and the magnetic properties were
The presence or absence of surface flaws and the state of secondary recrystallization were investigated. Table 4 shows the obtained results.

第４表から明らかなように、この発明に従ってスラブ
加熱を実施することにより、インヒビターの複合添加に
おいても、先の実施例と同様に効果のあることがわか
る。 As is evident from Table 4, by performing the slab heating according to the present invention, it can be seen that the compound addition of the inhibitor is as effective as in the previous examples.

実施例５ C:0.035％、Si:3.15％、Mn:0.073％、P:0.023％、Se:
0.017％、Sn:0.11％、Ge:0.015％を含有し残部実質的に
Feよりなる、210mm厚のスラブを実施例１と同様の条件
で加熱し、3.0mm厚の熱延板とした。該熱延鋼板を酸洗
し、１次冷間圧延で0.95mm厚とし、ついで1100℃、１分
間の焼鈍を施し、２次冷間圧延で0.35mmの最終厚みに仕
上げた。引続き湿水素中で820℃、３分間の脱炭焼鈍を
施したのち、MgOを主成分とする焼鈍分離剤を塗布し、
水素中で1150℃、10時間の仕上焼鈍を施して方向性けい
素鋼板とした。得られた1030mm幅のコイルから両エッジ
15mmを除去した後、100mm幅のサンプルを10枚切り出し
磁気特性を測定した。同一サンプルについて表面疵の有
無および２次再結晶状況を調査した。得られた結果を第
５表に示す。Example 5 C: 0.035%, Si: 3.15%, Mn: 0.073%, P: 0.023%, Se:
0.017%, Sn: 0.11%, Ge: 0.015%, with the balance substantially
A 210 mm thick slab made of Fe was heated under the same conditions as in Example 1 to obtain a 3.0 mm thick hot rolled sheet. The hot-rolled steel sheet was pickled, subjected to primary cold rolling to a thickness of 0.95 mm, then annealed at 1100 ° C. for 1 minute, and finished to a final thickness of 0.35 mm by secondary cold rolling. After performing decarburizing annealing at 820 ° C. for 3 minutes in wet hydrogen, applying an annealing separator containing MgO as a main component,
Finish annealing was performed in hydrogen at 1150 ° C. for 10 hours to obtain a grain-oriented silicon steel sheet. Both edges from the obtained 1030mm wide coil
After removing 15 mm, ten 100 mm wide samples were cut out and the magnetic properties were measured. The same sample was examined for surface flaws and secondary recrystallization. Table 5 shows the obtained results.

第５表から明らかなように、この発明に従ってスラブ
加熱を実施することにより表面疵および帯状細粒を発生
させず、磁気特性の均一化が図れる。 As is clear from Table 5, by performing slab heating according to the present invention, surface defects and band-like fine grains are not generated, and the magnetic properties can be made uniform.

実施例６ C:0.033％、Si:3.25％、Mn:0.083％、Cu:0.080％、C
r:0.020％、Te:0.010％、Bi:0.012％を含み、残部実質
的にFeよりなる、200mm厚のスラブを実施例３と同様の
条件で加熱し、1.8mm厚の熱延板とした。該熱延板に110
0℃、１分間の焼鈍を施した後、ついで1100℃、２分間
の中間焼鈍を施し、２次冷間圧延で0.20mmの最終板厚に
仕上げた。引続き湿水素中で830℃、３分間の脱炭焼鈍
を施したのち、MgOを主成分とする焼鈍分離剤を塗布
し、水素中で1200℃、10時間の仕上焼鈍を施して方向性
けい素鋼板とした。得られた1030mm幅のコイルから両エ
ッジ15mmを除去した後、100mm幅のサンプルを10枚切り
出し磁気特性を測定した。同一サンプルについて表面疵
の有無および２次再結晶状況もあわせて調査した。得ら
れた結果を第６表に示す。Example 6 C: 0.033%, Si: 3.25%, Mn: 0.083%, Cu: 0.080%, C
A 200 mm thick slab containing r: 0.020%, Te: 0.010%, and Bi: 0.012%, and substantially consisting of the remainder, Fe, was heated under the same conditions as in Example 3 to obtain a 1.8 mm thick hot rolled sheet. . 110
After annealing at 0 ° C. for 1 minute, intermediate annealing was performed at 1100 ° C. for 2 minutes, and finished to a final thickness of 0.20 mm by secondary cold rolling. After decarburizing annealing in wet hydrogen at 830 ° C for 3 minutes, apply an annealing separator containing MgO as a main component and finish annealing in hydrogen at 1200 ° C for 10 hours to obtain directional silicon. A steel plate was used. After removing both edges of 15 mm from the obtained coil having a width of 1030 mm, ten samples having a width of 100 mm were cut out and the magnetic characteristics were measured. The same sample was also examined for surface flaws and secondary recrystallization. Table 6 shows the obtained results.

第６表から明らかなように、この発明に従ってスラブ
加熱を実施することにより表面疵および帯状細粒を発生
させず、磁気特性の向上と均一化が図れる。 As is evident from Table 6, by performing slab heating according to the present invention, surface defects and band-like fine grains are not generated, and the magnetic properties can be improved and uniformized.

（発明の効果） 以上説明したようにこの発明は、熱間圧延前のスラブ
加熱においてインヒビターを固溶するに際し、スラブを
固体と液体とが共存する温度域に一旦入れ、結晶粒の粗
大化を抑制するようにしたので、帯状細粒が発生しなく
なり、優れた磁気特性を均一に得ることができ、また表
面疵の発生も防止できるところから、製品品質の向上に
大きく寄与するものである。(Effects of the Invention) As described above, in the present invention, when the inhibitor is dissolved in the slab before hot rolling, the slab is once placed in a temperature range where a solid and a liquid coexist, and the crystal grains are coarsened. Since it is suppressed, band-like fine particles are not generated, excellent magnetic properties can be obtained uniformly, and generation of surface flaws can be prevented, which greatly contributes to improvement of product quality.

【図面の簡単な説明】 第１図はスラブ加熱条件とスラブ最大結晶粒径との関係
を示すグラフ、 第２図はスラブ加熱条件と製品板の表面疵との関係を示
すグラフ、 第３図はスラブ加熱条件と表面疵発生限界との関係を示
すグラフ、 第４図はスラブ加熱条件とスラブ最大結晶粒径との関係
において、この発明のスラブ二段階加熱の下限温度を示
すグラフ、 第５図はスラブ加熱条件と製品の磁束密度B₈との関係を
示すグラフである。BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a graph showing a relationship between a slab heating condition and a maximum crystal grain size of a slab, FIG. 2 is a graph showing a relationship between a slab heating condition and a surface flaw of a product plate, FIG. FIG. 4 is a graph showing the relationship between the slab heating conditions and the surface flaw occurrence limit; FIG. 4 is a graph showing the lower limit temperature of the slab two-stage heating of the present invention in the relationship between the slab heating conditions and the slab maximum crystal grain size; Figure is a graph showing the relationship between the magnetic flux density B ₈ of the slab heating conditions and product.

───────────────────────────────────────────────────── フロントページの続き (72)発明者 高宮 俊人 千葉県千葉市川崎町１番地 川崎製鉄株 式会社技術研究本部内 (72)発明者 小松原 道郎 千葉県千葉市川崎町１番地 川崎製鉄株 式会社技術研究本部内 ──────────────────────────────────────────────────続 き Continuing from the front page (72) Inventor Toshito Takamiya 1 Kawasaki-cho, Chiba-shi, Chiba Kawasaki Steel Corporation Research and Development Headquarters (72) Michio Komatsubara 1 Kawasaki-cho, Chiba-shi, Chiba Kawasaki Steel Corp. Shikisha Technology Research Division

Claims (1)

(57)【特許請求の範囲】(57) [Claims] 【請求項１】含けい素鋼スラブを加熱した後、熱間圧延
を施し、その後１回または中間焼鈍をはさむ２回以上の
冷間圧延を施して最終板厚に仕上げたのち、脱炭焼鈍を
施し、次いで鋼板表面に焼鈍分離剤を塗布してから、仕
上げ焼鈍を施す一連の工程によって一方向性けい素鋼板
を製造するに当たり、 上記のスラブ加熱に際し、保護ガス雰囲気中でスラブを
粒界偏析の少なくとも一部が溶融する温度域に達するま
で加熱し、その後1380〜1440℃の温度域に５〜60min保
持することを特徴とする磁気特性の均一な一方向性けい
素鋼板の製造方法。(1) After heating a silicon steel slab, hot rolling is performed, and then cold rolling is performed once or two or more times including intermediate annealing to finish to a final sheet thickness, and then decarburizing annealing is performed. After applying an annealing separator to the steel sheet surface, and then producing a unidirectional silicon steel sheet by a series of steps of finish annealing, the slab is heated at the above slab heating, and the slab is grain-bounded in a protective gas atmosphere. A method for producing a unidirectional silicon steel sheet having uniform magnetic properties, wherein the steel sheet is heated until a temperature range in which at least a part of the segregation is melted, and then maintained at a temperature range of 1380 to 1440 ° C. for 5 to 60 minutes.