JPH05331532A - Method for heating slab - Google Patents
Method for heating slabInfo
- Publication number
- JPH05331532A JPH05331532A JP13887592A JP13887592A JPH05331532A JP H05331532 A JPH05331532 A JP H05331532A JP 13887592 A JP13887592 A JP 13887592A JP 13887592 A JP13887592 A JP 13887592A JP H05331532 A JPH05331532 A JP H05331532A
- Authority
- JP
- Japan
- Prior art keywords
- heating
- heating furnace
- slab
- dew point
- scale
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Pending
Links
Landscapes
- Control Of Heat Treatment Processes (AREA)
Abstract
Description
【０００１】[0001]
【産業上の利用分野】本発明は、スラブの加熱方法に関
し、さらに詳しくは連鋳機で発生したスラブ表層の鋳造
欠陥を加熱炉でスケールオフさせ表面品質が良好な熱延
鋼板を得る方法に関する。BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for heating a slab, and more particularly to a method for obtaining a hot-rolled steel sheet having good surface quality by scaling off casting defects in the surface layer of a slab generated by a continuous casting machine in a heating furnace. ..
【０００２】[0002]
【従来の技術】熱間圧延における加熱炉の燃料コストは
大きな割合を占める。そこで、燃料コストの低減、歩止
向上のために連続鋳造ラインから供給される高温のスラ
ブを短時間内に加熱炉に装入し、あるいはそのまま圧延
に供するいわゆる直送圧延技術が採用されている。この
ことは例えば「日本鉄鋼協会編：第２版 わが国におけ
る最近のホットストリップ製造技術（Ｐ４２〜）Ｓ６２
／８に詳しく記載されている。この直送圧延の実施によ
り、加熱炉へ装入するスラブ温度の高温化により燃料原
単位が低減されることはもちろんであるが、加熱炉での
加熱時間も大幅に短縮されるので、加熱炉内で発生する
スケールも減少し、製品の歩止り向上の面でも好まし
い。Fuel costs for heating furnaces in hot rolling account for a large proportion. Therefore, in order to reduce the fuel cost and improve the retention, a so-called direct feed rolling technique is employed in which a high temperature slab supplied from a continuous casting line is charged into a heating furnace within a short time or is directly subjected to rolling. This means, for example, "The Iron and Steel Institute of Japan: Second Edition, Recent Hot Strip Manufacturing Technology in Japan (P42 ~) S62.
/ 8. This direct feed rolling not only reduces the fuel consumption rate by raising the temperature of the slab charged to the heating furnace, but also significantly shortens the heating time in the heating furnace. The scale generated in step 1 is also reduced, which is also preferable in terms of improving the product yield.
【０００３】さらに最近の圧延ラインでは生産性向上の
ため圧延速度が速く、その結果加熱炉抽出〜圧延完了ま
での時間が短くなり、圧延材の圧延中温度低下量が小さ
く、加熱炉の抽出温度を低温となっている。この結果加
熱炉内で発生するスケール量は一層減少するわけであ
る。Further, in recent rolling lines, the rolling speed is high in order to improve the productivity, and as a result, the time from the extraction of the heating furnace to the completion of rolling is shortened, the decrease in the temperature of the rolled material during rolling is small, and the extraction temperature of the heating furnace is small. The temperature is low. As a result, the amount of scale generated in the heating furnace is further reduced.
【０００４】[0004]
【発明が解決しようとする課題】高温スラブの直送圧延
化及び圧延速度の高速化に伴う加熱炉抽出温度の低温化
により、炉内で発生するスケールは大幅に減少し、製品
歩止りの向上の面からは好ましいが、一方、連続鋳造機
で鋳造されたスラブの表層には不可避的に鋳造欠陥が存
在する。この鋳造欠陥は表層への不純物の濃縮、モール
ドパウダーの巻き込みなどに起因するものである。従来
は、この鋳造欠陥は加熱炉でスケールとして除去されて
いたが、スケール発生量の低減と共に、加熱炉抽出時に
鉄側に残ってしまい、圧延後の製品の表面欠陥によると
いう問題が発生していた。このため、表面品要求の高い
ものは直送圧延ができず、燃料原単位も悪化していた。Due to the direct feed rolling of the high temperature slab and the lowering of the heating furnace extraction temperature accompanying the higher rolling speed, the scale generated in the furnace is greatly reduced and the product yield is improved. Although preferable from the aspect, casting defects are unavoidably present on the surface layer of the slab cast by the continuous casting machine. This casting defect is caused by concentration of impurities in the surface layer, inclusion of mold powder, and the like. Conventionally, this casting defect was removed as scale in a heating furnace, but with the reduction in the amount of scale generation, it remained on the iron side during extraction of the heating furnace, causing the problem of surface defects in the product after rolling. It was For this reason, those with a high demand for surface products could not be directly rolled, and the fuel consumption rate was worse.
【０００５】加熱雰囲気の制御によりスケールオフ量を
制御することについては特開昭５３−１４０２１２号公
報に雰囲気中の酸素濃度を調整する技術が開示されてい
るが、加熱バーナの空燃比の調整では、酸素濃度の調整
範囲が狭く充分なスケールオフ量が得られない。本発明
は短時間の加熱炉在炉中にスラブ表層のスケールオフ量
を適正化する方法を提供することを目的とする。Regarding the control of the scale-off amount by controlling the heating atmosphere, Japanese Patent Application Laid-Open No. 53-140212 discloses a technique for adjusting the oxygen concentration in the atmosphere. However, in the adjustment of the air-fuel ratio of the heating burner. However, the oxygen concentration adjustment range is narrow and a sufficient scale-off amount cannot be obtained. An object of the present invention is to provide a method for optimizing the scale-off amount of the slab surface layer during a short time in a heating furnace.
【０００６】[0006]
【課題を解決するための手段】本発明は熱間圧延用スラ
ブを加熱するに当り、加熱炉内へ水分を供給し、加熱炉
内の露点を調整することを特徴とするスラブの加熱方法
である。また、スラブ加熱温度をＴ（℃）、加熱時間を
Ｈ（分）としたときに、次の（１）式により加熱炉内の
露点Ｗ（℃）を調整するスラブの加熱方法である。Means for Solving the Problems The present invention is a slab heating method characterized in that, when heating a slab for hot rolling, water is supplied into the heating furnace to adjust the dew point in the heating furnace. is there. Moreover, when the slab heating temperature is T (° C.) and the heating time is H (minute), the dew point W (° C.) in the heating furnace is adjusted by the following equation (1).
【０００７】 Ｗ＝５．８５×１０5 ／（Ｔ＋２７３） −１．５Ｈ＋６．３×１０-3Ｈ2 −２９４ …（１） さらにこの場合、加熱炉内の露点の調整を加熱炉内に水
分を供給することにより行うとよい。W = 5.85 × 10 5 / (T + 273) −1.5H + 6.3 × 10 −3 H 2 −294 (1) Further, in this case, the dew point in the heating furnace is adjusted to obtain moisture in the heating furnace. Is preferably supplied.
【０００８】[0008]
【作用】発明者らは、前記スラブの鋳造欠陥の分布を調
査した結果、スラブ表層から０．５ｍｍの位置までに集
中していることを確認した。つまり、加熱炉内で表層
０．５ｍｍをスケールとして除去できれば前記問題点を
解決できるわけである。さらに鉄の酸化（スケールの発
生）は酸素雰囲気よりも、水蒸気雰囲気の方が促進され
るということを実験により確認した。As a result of investigating the distribution of casting defects of the slab, the inventors have confirmed that they are concentrated from the surface layer of the slab to a position of 0.5 mm. That is, if the surface layer of 0.5 mm can be removed as a scale in the heating furnace, the above problems can be solved. Furthermore, it was confirmed by experiments that the oxidation of iron (generation of scale) was promoted in a water vapor atmosphere rather than in an oxygen atmosphere.
【０００９】上記２点の結果から短時間の加熱時間であ
っても加熱時間と加熱温度に見合った適切な露点に調整
することにより鋳造欠陥が確実にスケールとして除去で
き、良好な製品表面品質が得られることを見出したわけ
である。また炉内雰囲気の露点は通常、燃料の組成によ
り決定されているので、加熱炉内へ水分を供給して所定
の露点に調整可能としたものである。From the above two results, even if the heating time is short, by adjusting the dew point to be suitable for the heating time and the heating temperature, casting defects can be surely removed as scales, and good product surface quality can be obtained. We have found that it can be obtained. Further, since the dew point of the atmosphere in the furnace is usually determined by the composition of the fuel, it is possible to adjust the dew point to a predetermined value by supplying water into the heating furnace.
【００１０】図１に加熱時間、加熱温度とスケールオフ
量０．５ｍｍを達成するのに必要な露点の調査結果を示
す。これを式で表すと Ｗ＝５．８５×１０5 ／（Ｔ＋２７３） −１．５Ｈ＋６．３×１０-3Ｈ2 −２９４ …（１） ただし、 Ｗ：露点（℃） Ｔ：加熱温度（℃） Ｈ：加熱時間（ｍｉｎ） となる。つまり、この露点Ｗ以上に加熱炉雰囲気の露点
を調整することにより、鋳造欠陥の集中するスラブ表層
から０．５ｍｍの範囲は加熱炉でスケールオフされ、良
好な表面品質の製品の製造が可能となる。一方、通常燃
料の燃焼ガスの露点は５０〜６０℃であり、これ以上の
露点雰囲気が必要な加熱条件では燃焼用空気または燃料
に水蒸気を吹き込み、炉内の露点を所定の値に調整する
ことにより、安定して鋳造欠陥をスケールとして除去で
きるようになる。FIG. 1 shows the investigation results of the heating time, the heating temperature and the dew point required to achieve the scale-off amount of 0.5 mm. When this is expressed by an equation, W = 5.85 × 10 5 / (T + 273) −1.5H + 6.3 × 10 −3 H 2 -294 (1) where W: dew point (° C.) T: heating temperature (° C. ) H: The heating time (min) is reached. That is, by adjusting the dew point of the heating furnace atmosphere to be equal to or higher than the dew point W, the range of 0.5 mm from the slab surface layer where casting defects are concentrated is scaled off in the heating furnace, and it is possible to manufacture a product with good surface quality. Become. On the other hand, the dew point of the combustion gas of normal fuel is 50 to 60 ° C, and under heating conditions requiring a dew point atmosphere higher than this, steam is blown into the combustion air or fuel to adjust the dew point in the furnace to a predetermined value. Thereby, it becomes possible to stably remove the casting defect as a scale.
【００１１】なお、以上は加熱炉内へ水分を供給して露
点を（１）式以上とする点について述べてきたが他に燃
料組成を変えて、例えば水素Ｈ2 とか、メタンＣＨ4 成
分を増加させる等により露点を（１）式以上としてもよ
い。The above description has been made on the point that the dew point is made to be equal to or higher than the formula (1) by supplying water into the heating furnace, but the fuel composition may be changed to, for example, hydrogen H 2 or methane CH 4 component. The dew point may be set to the expression (1) or higher by increasing it.
【００１２】[0012]
【実施例】２６０ｍｍ厚のスラブを粗圧延機、仕上圧延
機で製品厚３．２ｍｍまで熱間圧延をし、製品の表面状
況を確認した。加熱炉の燃料組成（体積％）を表１に示
した。この燃料の燃焼排ガスの露点は５６℃である。ス
ラブの加熱条件は、加熱温度１２００℃、加熱時間３０
分とした。この条件で必要なスケールオフ厚を得るため
には露点を式（１）によって求めると６４℃となる。そ
こで炉内に水蒸気を供給して露点を６５℃に調整した。Example A 260 mm thick slab was hot-rolled to a product thickness of 3.2 mm with a rough rolling machine and a finishing rolling machine, and the surface condition of the product was confirmed. The fuel composition (volume%) of the heating furnace is shown in Table 1. The combustion exhaust gas of this fuel has a dew point of 56 ° C. The heating conditions for the slab are a heating temperature of 1200 ° C and a heating time of 30.
Minutes In order to obtain the necessary scale-off thickness under these conditions, the dew point is calculated by the equation (1), which is 64 ° C. Therefore, steam was supplied into the furnace to adjust the dew point to 65 ° C.
【００１３】比較例として、露点以外は同一条件で加
熱、圧延した。As a comparative example, heating and rolling were performed under the same conditions except for the dew point.
【００１４】[0014]
【表１】 （体積％） ──────────────────────────────────── Ｈ2 ＣＯ ＣＨ4 Ｎ2 ＣＯ2 Ｃ2 Ｈ4 ２７．４ １３．２ １２．０ ３２．０ １４．２ １．２ ──────────────────────────────────── 製品表面品質の調査結果を表２に示した。露点５６℃で
加熱した比較例では、鋳造欠陥に起因する表面欠陥が多
発したが、本願による蒸気投入方法で露点を６５℃とし
た場合には欠陥のない良好な表面品質の製品を得ること
ができた。[Table 1] (Volume%) ──────────────────────────────────── H 2 CO CH 4 N 2 CO 2 C 2 H 4 27.4 13.2 12.0 32.0 14.2 1.2 ────────────────────────── ─────────── Table 2 shows the survey results of the product surface quality. In the comparative example heated at the dew point of 56 ° C., surface defects caused by casting defects frequently occurred, but when the dew point of the steam injection method according to the present application was set at 65 ° C., a product having good surface quality without defects could be obtained. did it.
【００１５】[0015]
【表２】 ──────────────────────────────────── 加熱炉露点 加熱炉でのスケールオフ厚 鋳造欠陥起因の欠陥個数 （℃） （ｍｍ） （１ｍ2 当り） ６５ ０．５ ０個 ５６ ０．３ ５０個 ────────────────────────────────────[Table 2] ──────────────────────────────────── Heating furnace dew point Scale-off thickness in heating furnace Number of defects due to casting defects (℃) (mm) (per 1 m 2 ) 65 0.5 0 56 56 0.3 50 ────────────────────── ───────────────
【００１６】[0016]
【発明の効果】本発明のスラブ加熱方法によれば、加熱
条件に応じた適切な加熱炉内雰囲気露点により、連鋳機
に起因するスラブ表層の鋳造欠陥を加熱炉内でスケール
として除去することができ、良好な表面品質の製品の製
造が可能になった。According to the slab heating method of the present invention, the casting defects in the surface layer of the slab caused by the continuous casting machine are removed as scales in the heating furnace by an appropriate atmosphere dew point in the heating furnace according to the heating conditions. It is possible to manufacture a product having good surface quality.
【図１】加熱時間、加熱温度と最適な露点の関係を示す
図である。FIG. 1 is a diagram showing a relationship between a heating time, a heating temperature and an optimum dew point.
フロントページの続き (72)発明者 竹嶋 力男 千葉市中央区川崎町１番地 川崎製鉄株式 会社千葉製鉄所内 (72)発明者 吉田 邦雄 千葉市中央区川崎町１番地 川崎製鉄株式 会社千葉製鉄所内 (72)発明者 武智 敏貞 千葉市中央区川崎町１番地 川崎製鉄株式 会社千葉製鉄所内Front page continued (72) Inventor Rikio Takeshima 1 Kawasaki-cho, Chuo-ku, Chiba City Chiba Steel Works, Ltd. (72) Inventor Kunio Yoshida 1 Kawasaki-cho, Chuo-ku, Chiba City Chiba Works ( 72) Inventor Toshisada Takechi 1 Kawasaki-cho, Chuo-ku, Chiba City Kawasaki Steel Co., Ltd. Chiba Works
Claims (3)
熱炉内へ水分を供給し、加熱炉内の露点を調整すること
を特徴とするスラブの加熱方法。1. A method for heating a slab, wherein when heating a slab for hot rolling, water is supplied into the heating furnace to adjust the dew point in the heating furnace.
Ｈ（分）としたときに、次式により加熱炉内の露点Ｗ
（℃）を調整することを特徴とするスラブの加熱方法。 Ｗ＝５．８５×１０5 ／（Ｔ＋２７３） −１．５Ｈ＋６．３×１０-3Ｈ2 −２９４2. When the slab heating temperature is T (° C.) and the heating time is H (minutes), the dew point W in the heating furnace is calculated by the following equation.
(C) is adjusted, The heating method of the slab characterized by the above-mentioned. W = 5.85 × 10 5 / (T + 273) −1.5H + 6.3 × 10 −3 H 2 −294
を供給することである請求項２記載のスラブの加熱方
法。3. The method for heating a slab according to claim 2, wherein the adjustment of the dew point in the heating furnace is to supply water into the heating furnace.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP13887592A JPH05331532A (en) | 1992-05-29 | 1992-05-29 | Method for heating slab |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP13887592A JPH05331532A (en) | 1992-05-29 | 1992-05-29 | Method for heating slab |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| JPH05331532A true JPH05331532A (en) | 1993-12-14 |
Family
ID=15232158
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| JP13887592A Pending JPH05331532A (en) | 1992-05-29 | 1992-05-29 | Method for heating slab |
Country Status (1)
| Country | Link |
|---|---|
| JP (1) | JPH05331532A (en) |
Cited By (6)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US5818490A (en) * | 1996-05-02 | 1998-10-06 | Array Printers Ab | Apparatus and method using variable control signals to improve the print quality of an image recording apparatus |
| US5818480A (en) * | 1995-02-14 | 1998-10-06 | Array Printers Ab | Method and apparatus to control electrodes in a print unit |
| US5847733A (en) * | 1996-03-22 | 1998-12-08 | Array Printers Ab Publ. | Apparatus and method for increasing the coverage area of a control electrode during direct electrostatic printing |
| US5956064A (en) * | 1996-10-16 | 1999-09-21 | Array Printers Publ. Ab | Device for enhancing transport of proper polarity toner in direct electrostatic printing |
| US5959648A (en) * | 1996-11-27 | 1999-09-28 | Array Printers Ab | Device and a method for positioning an array of control electrodes in a printhead structure for direct electrostatic printing |
| JP2007231316A (en) * | 2006-02-28 | 2007-09-13 | Jfe Steel Kk | Method for producing hot-rolled steel plate |
Citations (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JPS63123516A (en) * | 1986-11-13 | 1988-05-27 | Kawasaki Steel Corp | Heating method for continuously cast slab of ferritic stainless steel |
| JPH01263216A (en) * | 1988-04-14 | 1989-10-19 | Kawasaki Steel Corp | Device for supplying humidification in atmospheric gas |
-
1992
- 1992-05-29 JP JP13887592A patent/JPH05331532A/en active Pending
Patent Citations (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JPS63123516A (en) * | 1986-11-13 | 1988-05-27 | Kawasaki Steel Corp | Heating method for continuously cast slab of ferritic stainless steel |
| JPH01263216A (en) * | 1988-04-14 | 1989-10-19 | Kawasaki Steel Corp | Device for supplying humidification in atmospheric gas |
Cited By (6)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US5818480A (en) * | 1995-02-14 | 1998-10-06 | Array Printers Ab | Method and apparatus to control electrodes in a print unit |
| US5847733A (en) * | 1996-03-22 | 1998-12-08 | Array Printers Ab Publ. | Apparatus and method for increasing the coverage area of a control electrode during direct electrostatic printing |
| US5818490A (en) * | 1996-05-02 | 1998-10-06 | Array Printers Ab | Apparatus and method using variable control signals to improve the print quality of an image recording apparatus |
| US5956064A (en) * | 1996-10-16 | 1999-09-21 | Array Printers Publ. Ab | Device for enhancing transport of proper polarity toner in direct electrostatic printing |
| US5959648A (en) * | 1996-11-27 | 1999-09-28 | Array Printers Ab | Device and a method for positioning an array of control electrodes in a printhead structure for direct electrostatic printing |
| JP2007231316A (en) * | 2006-02-28 | 2007-09-13 | Jfe Steel Kk | Method for producing hot-rolled steel plate |
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