JP2809464B2 - Continuous casting of thin cast slab - Google Patents
Continuous casting of thin cast slabInfo
- Publication number
- JP2809464B2 JP2809464B2 JP4099190A JP4099190A JP2809464B2 JP 2809464 B2 JP2809464 B2 JP 2809464B2 JP 4099190 A JP4099190 A JP 4099190A JP 4099190 A JP4099190 A JP 4099190A JP 2809464 B2 JP2809464 B2 JP 2809464B2
- Authority
- JP
- Japan
- Prior art keywords
- molten metal
- scum
- temperature
- slab
- continuous casting
- 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.)
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- Continuous Casting (AREA)
Description
【発明の詳細な説明】 〔産業上の利用分野〕 本発明は、ツインドラム方式のように、冷却ドラムの
周面の一部に湯溜り部を形成し、そこに注入した溶融金
属を冷却・凝固して、薄肉鋳片を製造する連続鋳造方法
に関する。DETAILED DESCRIPTION OF THE INVENTION [Industrial Application Field] The present invention forms a pool in a part of the peripheral surface of a cooling drum and cools and melts the molten metal injected therein, as in a twin drum system. The present invention relates to a continuous casting method for producing a thin cast piece by solidification.
近来、溶鋼等の溶融金属か直接最終形状に近い数mm〜
数十mm程度の肉厚をもつ薄肉鋳片を製造する方法が注目
されている。この連続鋳造法によるとき、従来のような
多段階にわたる熱延工程を必要とせず、また最終形状に
するための圧延も軽度なもので済むため、工程及び設備
の簡略化を図ることができる。In recent years, molten metal such as molten steel or several mm
Attention has been focused on a method for producing a thin cast piece having a thickness of about several tens of mm. According to the continuous casting method, a hot rolling process in multiple stages as in the related art is not required, and the rolling for obtaining the final shape can be light, so that the processes and equipment can be simplified.
この種の連続鋳造法として、互いに逆方向に回転する
一対の冷却ドラムの間に湯溜り部を形成するツインドラ
ム方式、冷却ドラムとベルトとの間に湯溜り部を形成す
るドラム−ベルト方式、一本の冷却ドラムの周面一部に
湯溜り部を形成する単ドラム方式等がある。これらの方
式においては、いずれも冷却ドラムの周面に接する部分
で、溶融金属の冷却・凝固が進行し、凝固シェルを生成
する。従って、この凝固シェルを安定して成長せしめる
ことが良好な表面性状を有する薄肉鋳片を得るために極
めて重要である。As a continuous casting method of this kind, a twin drum system in which a pool is formed between a pair of cooling drums rotating in opposite directions, a drum-belt system in which a pool is formed between a cooling drum and a belt, There is a single drum system in which a pool is formed on a part of the peripheral surface of one cooling drum. In each of these methods, cooling and solidification of the molten metal proceeds at a portion in contact with the peripheral surface of the cooling drum to generate a solidified shell. Therefore, it is extremely important to stably grow the solidified shell in order to obtain a thin cast piece having good surface properties.
しかし、かゝる鋳造を行うに際し、湯溜り部に注入さ
れた溶融金属（溶湯）の表層に浮遊する酸化物（スカ
ム）が、冷却ドラムの回転と共に流動する溶湯に付随し
て生成中の凝固シェルに巻き込まれる場合があり、この
結果、鋳造された薄肉鋳片に肌荒れや割れ等の欠陥が発
生する。However, when such casting is performed, the oxide (scum) floating on the surface layer of the molten metal (molten metal) injected into the pool is solidified during the formation of the molten metal flowing along with the rotation of the cooling drum. The thin cast slab may be entangled in the shell, and as a result, defects such as rough skin and cracks may occur in the cast thin slab.
この問題を解消するために、湯溜り部を非酸化性雰囲
気としてスカム発生を抑制する技術が提案されている
（特開昭62−130749号公報参照）。In order to solve this problem, a technique has been proposed in which the pool is made non-oxidizing in atmosphere to suppress the generation of scum (see JP-A-62-130749).
しかしながら、湯溜り部を非酸化性雰囲気にしても冷
却ドラムの隙間より該冷却ドラムの回転に伴って外気が
引き込まれたり、また、溶湯の種類や清浄度によって溶
湯から不純物が浮上する場合があり、スカム生成を完全
に防止することは困難である。However, even if the basin is in a non-oxidizing atmosphere, outside air may be drawn in from the gap of the cooling drum with the rotation of the cooling drum, or impurities may float from the molten metal depending on the type and cleanliness of the molten metal. It is difficult to completely prevent scum formation.
そこで本発明は湯溜り部内の湯面上に生成するスカム
の組成を改善することにより、スカムに起因する鋳片欠
陥の発生を防止して表面割れの少ない優れた品質の薄鋳
片を製造するものである。Therefore, the present invention improves the composition of scum generated on the surface of the molten metal in the basin, thereby preventing the occurrence of slab defects caused by scum and producing a thin slab of excellent quality with less surface cracks. Things.
本発明の薄肉鋳片の連続鋳造方法は、前記目的を達成
するために、不活性雰囲気中で冷却ドラム周面により溶
湯を急冷・凝固するに際し、溶湯表面に浮遊するスカム
のうち、温度降下時に最初に析出する酸化物組成の析出
温度を該溶湯金属の液相線温度以下に調整することを特
徴とする。この調整を溶湯中の溶存酸素濃度と不活性雰
囲気中の酸素濃度の関係において行うものである。The continuous casting method of the thin cast slab of the present invention, in order to achieve the above object, when quenching and solidifying the molten metal by the peripheral surface of the cooling drum in an inert atmosphere, of the scum floating on the molten metal surface, It is characterized in that the deposition temperature of the oxide composition to be deposited first is adjusted to the liquidus temperature of the molten metal or lower. This adjustment is performed based on the relationship between the dissolved oxygen concentration in the molten metal and the oxygen concentration in the inert atmosphere.
本発明は、湯溜り部内の湯面に浮遊するスカムのう
ち、温度降下時に最初に析出する酸化物組成の析出温度
を該溶融金属の液相線温度以下に調整するとスカムが凝
固シェルに巻込まれても、鋳片表面に割れを発生しない
という新しい知見に基づいて成されたものである。According to the present invention, among the scums floating on the surface of the molten metal in the basin, when the deposition temperature of the oxide composition that is first deposited at the time of the temperature drop is adjusted to the liquidus temperature of the molten metal or less, the scum is caught in the solidified shell. However, it has been made based on a new finding that cracks do not occur on the slab surface.
以下、本発明を詳細に説明する。先ず、鋳造中に採取
したスカムの組成中、温度降下の際、最初に析出した酸
化物相の析出温度と、このスカムが巻込まれて鋳造され
た鋳片の縦割れ発生量との関係を第１図に示す。Hereinafter, the present invention will be described in detail. First, in the composition of the scum collected during casting, the relationship between the deposition temperature of the oxide phase initially deposited at the time of the temperature drop and the amount of vertical cracks generated in the cast slab in which this scum was involved was cast. It is shown in FIG.
第１図はステンレス鋼の内、第１表に示す成分を有す
るCr−Ni系ステンレス鋼を試験材に選択し、第３図に示
す冷却ドラム2a,2bを備えた連続鋳造装置により薄鋳片
８を製造したときに、上記装置における湯溜り部４の閉
鎖空間６内の雰囲気酸素濃度を種々変化させ、その際に
前記湯溜り部４の湯面に浮遊しているスカム11（スカム
成分:SiO2−MnO−Al2O3−CaO−Cr2O3−FeO）を採取し
て、温度降下時に最初に析出するスカム中酸化物相の析
出温度を求め、鋳片に発生した縦割れ量との関係を示し
たものである。なお、この析出温度は、多元系状態図か
ら求めた。FIG. 1 shows a sample selected from Cr-Ni stainless steel having the components shown in Table 1 among the stainless steels, and thin cast slabs obtained by a continuous casting apparatus having cooling drums 2a and 2b shown in FIG. When the scum 11 is manufactured, the oxygen concentration of the atmosphere in the closed space 6 of the basin 4 in the above apparatus is changed variously, and the scum 11 (scum component: (SiO 2 -MnO-Al 2 O 3 -CaO-Cr 2 O 3 -FeO) is sampled, and the deposition temperature of the oxide phase in the scum which precipitates first when the temperature drops is determined. It shows the relationship with. The deposition temperature was determined from a multi-phase diagram.
第１図によると、スカム中で、温度降下時に最初に析
出する酸化物相の析出温度がステンレス鋼の液相線（14
50℃）以下の場合に、鋳片の縦割れが発生しないことが
わかる。その理由は、酸化物相の析出温度が該溶融金属
の液相線以上であると、一部固体を含むスカムが巻込ま
れ、この固体スカムが巻込まれた部分には凝固遅れが生
じて、結局、ここが起点となって割れが生じる。一方、
完全に液体であるスカムが巻込まれても部分的な凝固遅
れ部の発生はなく、割れは生じないと考えられる。 According to FIG. 1, in the scum, the precipitation temperature of the oxide phase which first precipitates when the temperature drops is lower than the liquidus line of stainless steel (14).
It can be seen that when the temperature is below 50 ° C), no vertical cracking of the slab occurs. The reason is that if the deposition temperature of the oxide phase is equal to or higher than the liquidus of the molten metal, scum containing a part of solids is entrained, and solidification delay occurs in the part where the solid scum is entrained. This is the starting point for cracking. on the other hand,
Even if scum which is completely liquid is involved, there is no occurrence of a partial solidification delay portion, and it is considered that cracking does not occur.
一方、溶鋼成分と鋳片割れ発生量の関係をみると、鋳
片割れ発生量は溶鋼の脱酸成分にも大きく影響される。
すなわち、Si−Mn系の脱酸成分の場合は、スカム成分と
してSiO2−MnOを主要成分とすることができるので鋳片
割れを防止できる。これは、鋳片割れの発生率が溶鋼中
のSiとMnの含有量の比（Si/Mn）によって規定されるた
めである。第２図はSi及びMn以外の成分が第１表の化学
成分よりなる溶鋼においてSiとMnの濃度すなわち含有量
の比（Si/Mn）を種々変化させ、該溶鋼湯溜り部の雰囲
気中酸素濃度（％）との関係を示したもので、斜線を施
していないところが鋳片割れの発生しない範囲（図中○
印：割れなし、×印：割れあり）である。図中、比Si/M
nの上限は、スカム成分中の高融点酸化物SiO2の析出
によって規制されており、この値はSUS304組成ではほぼ
１である。また、比Si/Mnの下限は、スカム成分中の
高融点酸化物Cr2O3の析出によって規制され、この値はS
US304組成で0.02である。On the other hand, looking at the relationship between the molten steel component and the amount of slab cracking, the amount of slab cracking is greatly affected by the deoxidizing component of the molten steel.
That is, in the case of a Si-Mn-based deoxidizing component, a scum component can be mainly composed of SiO 2 -MnO, so that slab cracks can be prevented. This is because the rate of occurrence of slab cracks is defined by the ratio of the contents of Si and Mn in the molten steel (Si / Mn). FIG. 2 shows various changes in the concentration of Si and Mn, that is, the ratio of the contents (Si / Mn), in the molten steel in which the components other than Si and Mn are the chemical components shown in Table 1. It shows the relationship with the concentration (%), and the area without hatching is the range where slab cracks do not occur (○ in the figure)
Mark: no crack, x mark: cracked). In the figure, the ratio Si / M
The upper limit of n is restricted by the refractory oxide SiO 2 deposition in scum component, this value is approximately 1 in SUS304 composition. Further, the lower limit of the ratio Si / Mn is regulated by the precipitation of the high melting point oxide Cr 2 O 3 in the scum component, and this value is S
0.02 for US304 composition.
一方、雰囲気中酸素濃度が上限を超えると、SiO2が
析出する。この範囲は、比Si/Mnの値によって影響され
る。その理由は次の通りである。すなわち、Si濃度が高
いと、雰囲気中酸素濃度が低くてもSiは酸化されやすく
なり、SiO2が容易に析出するようになる。それに対し
て、Mn濃度が高くなると、溶鋼表面より蒸発するMn量が
増加し、溶鋼と雰囲気ガスとの界面に存在する酸素と反
応する。それに伴って、界面酸素濃度が雰囲気中の酸素
濃度よりも実質的に低下し、SiO2の析出は抑えられる。
そのため、雰囲気中酸素濃度の上限を規定する境界線
は負の傾きとなる。なおここでは、雰囲気中酸素濃度の
下限を工業的に制御可能な範囲すなわち１×10-3％と
した。On the other hand, when the oxygen concentration in the atmosphere exceeds the upper limit, SiO 2 is precipitated. This range is affected by the value of the ratio Si / Mn. The reason is as follows. That is, when the Si concentration is high, even if the oxygen concentration in the atmosphere is low, Si is easily oxidized, and SiO 2 is easily precipitated. On the other hand, when the Mn concentration increases, the amount of Mn evaporating from the surface of the molten steel increases, and reacts with oxygen present at the interface between the molten steel and the atmosphere gas. Along with this, the interface oxygen concentration is substantially lower than the oxygen concentration in the atmosphere, and the deposition of SiO 2 is suppressed.
Therefore, the boundary defining the upper limit of the oxygen concentration in the atmosphere has a negative slope. Here, the lower limit of the oxygen concentration in the atmosphere was set to a range that can be controlled industrially, that is, 1 × 10 −3 %.
以上のように、スカム中で最初に析出する酸化物組成
の析出温度（融点）を溶融金属すなわち溶融の液晶線以
下とするためには、溶鋼成分の比Si/Mnを0.02から1.0の
範囲とし、湯溜り部の雰囲気酸素濃度は上限が1.0〜1.5
％の範囲となるように維持しながら、且つ第２図に示す
ように、比Si/Mnに応じて雰囲気中の酸素濃度を調整す
る必要がある。As described above, in order to keep the deposition temperature (melting point) of the oxide composition first deposited in the scum below the molten metal, that is, the molten liquid crystal line, the ratio Si / Mn of the molten steel component should be in the range of 0.02 to 1.0. The upper limit of the oxygen concentration in the pool is 1.0 to 1.5.
%, And it is necessary to adjust the oxygen concentration in the atmosphere according to the ratio Si / Mn as shown in FIG.
また、主成分がCaO−SiO2−Au2O3系の介在物（鍋上ス
ラグを巻込んだもの）が浮上し、スカムといっしょに巻
込まれることもあるので、鍋上スラグの融点も溶融金属
（溶鋼）の液相線温度以下にするとともに、ノズル耐火
物等の高融点介在物を巻込ませないことも、第２図に基
づいて割れを抑える上での前提となる。Further, main component CaO-SiO 2 -Au 2 O 3 based inclusions (those involving pan on slag) floats because sometimes caught together with scum, also the melting point of the pot on the slag melt The fact that the temperature is not higher than the liquidus temperature of the metal (molten steel) and that high-melting point inclusions such as nozzle refractories are not involved are also prerequisites for suppressing cracking based on FIG.
以下、本発明を実施例に基づき説明する。 Hereinafter, the present invention will be described based on examples.
第１表の化学組成をもつCr−Ni系ステンレス鋼の内、
Si,Mnをその比Si/Mnが第２表に示す値となるように変え
てテストした。なお、Mnの値は、1.00％〜1.21％の範囲
とした。Among the Cr-Ni stainless steels having the chemical composition shown in Table 1,
Si and Mn were tested by changing their ratio Si / Mn to the values shown in Table 2. The value of Mn was in the range of 1.00% to 1.21%.
まず、第１表及び第２表に基づく化学組成の1500℃の
溶鋼を第３図に示す湯溜り部４へタンデッシュ１より注
湯ノズル11を介して注入した。冷却ドラム2a,2bとサイ
ド堰３で構成した湯溜り部４の上方に、密封室５で覆わ
れた閉鎖空間６が形成されているが、該閉鎖空間６へ不
活性ガスを注入して、該密封室内５の酸素濃度を第２表
に示すように調整した。 First, molten steel having a chemical composition of 1500 ° C. based on Tables 1 and 2 was poured into the pool 4 shown in FIG. 3 from the tundish 1 through the pouring nozzle 11. Above the pool 4 formed by the cooling drums 2a and 2b and the side weirs 3, a closed space 6 covered with a sealed chamber 5 is formed. Inert gas is injected into the closed space 6, The oxygen concentration in the sealed chamber 5 was adjusted as shown in Table 2.
その結果、第２表に示すように、スカム中で、降温時
に最初に析出する酸化物相の析出手段を調整しない従来
例に比較すると、本発明によれば、鋳片割れが著るしく
減少することが確認された。こゝで、第２表の の欄はスカム中で降温時に最初に析出する酸化物相の析
出温度を、 の欄は鋳片縦割れ指数（m/m2）を表わす。As a result, as shown in Table 2, in the scum, according to the present invention, slab cracks are remarkably reduced in comparison with the conventional example in which the means for precipitating the oxide phase which is first precipitated at the time of temperature decrease is not adjusted. It was confirmed that. Here, of Table 2 Column is the deposition temperature of the oxide phase that first precipitates when the temperature falls in the scum, Column shows the slab vertical crack index (m / m 2 ).
なお、以上の説明においては、ツインドラム方式の連
続鋳造装置を使用した場合について説明したが、本発明
はこれに拘束されるものではなく、また、Ni−Cr系ステ
ンレス鋼以外のステンレス鋼にも勿論適用される。In the above description, the case where a twin-drum continuous casting apparatus is used has been described.However, the present invention is not limited to this, and also applies to stainless steels other than Ni-Cr stainless steel. Of course it applies.
〔発明の効果〕 以上説明したように、本発明では、湯溜り部の上方空
間を不活性雰囲気にしてスカム量をできるだけ少なくす
るとともに、該湯溜り部の湯面に浮遊するスカムを融点
の低いスカムに調整するので、スカムが溶湯の流れに付
随して冷却ドラムに巻込まれても鋳片の縦割れが発生せ
ず、本発明により優れた薄肉鋳片を鋳造することができ
る。[Effects of the Invention] As described above, in the present invention, the amount of scum is reduced as much as possible by making the space above the basin an inert atmosphere, and the scum floating on the surface of the basin having a low melting point. Since the scum is adjusted to a scum, even if the scum is rolled into the cooling drum accompanying the flow of the molten metal, a vertical crack of the slab does not occur, and an excellent thin slab can be cast according to the present invention.
第１図はスカム中で温度降下時に最初に析出する酸化物
相の析出温度と鋳片の縦割れ発生量（m/m2）の関係を示
す図であり、 第２図は湯溜り部雰囲気中の酸素濃度（％）と溶鋼中の
Si/Mnとの関係で、鋳片縦割れの発生しない領域を示し
た図であり、 第３図はツインドラム方式の連続鋳造装置の概略を示す
断面側面図である。 １……タンデッシュ、2a,2b……冷却ドラム、 ３……サイド堰、４……湯溜り部、 ５……密封室、６……閉鎖空間、 ７……溶融金属、８……鋳片、 ９……ピンチロール、 10……タンデッシュスラグ、 11……注湯ノズル。FIG. 1 is a graph showing the relationship between the deposition temperature of an oxide phase which is deposited first when the temperature drops in a scum and the amount of vertical cracks (m / m 2 ) of a slab. FIG. Oxygen concentration (%) in molten steel
FIG. 3 is a view showing an area where vertical slab cracks do not occur in relation to Si / Mn. FIG. 3 is a cross-sectional side view schematically showing a twin-drum continuous casting apparatus. DESCRIPTION OF SYMBOLS 1 ... Tundesh, 2a, 2b ... Cooling drum, 3 ... Side dam, 4 ... Pool part, 5 ... Sealed room, 6 ... Closed space, 7 ... Molten metal, 8 ... Slab, 9 ... pinch roll, 10 ... tundish slag, 11 ... pouring nozzle.
Claims (2)
部とサイド堰で形成した湯溜り部に溶融金属を注入し、
次いで、該溶融金属を前記冷却ドラムの回転周面で冷
却、凝固しながら薄肉鋳片を製造する連続鋳造方法にお
いて、 前記溶融金属の表層に浮遊する酸化物のうち、温度降下
時に最初に析出する酸化物組成の析出温度を該溶融金属
の液相線温度以下に調整することを特徴とする薄肉鋳片
の連続鋳造方法。1. A molten metal is poured into a pool formed by a part of a peripheral surface of a cooling drum and a side dam in an inert atmosphere,
Then, in a continuous casting method for producing a thin-walled slab while cooling and solidifying the molten metal on the rotating peripheral surface of the cooling drum, among oxides floating on the surface layer of the molten metal, the oxide is first precipitated when the temperature is lowered. A continuous casting method for a thin cast slab, wherein a deposition temperature of an oxide composition is adjusted to a temperature not higher than a liquidus temperature of the molten metal.
不活性雰囲気中の酸素濃度により、前記酸化物のうち、
温度降下時に最初に析出する酸化物組成の析出温度を調
整する請求項１記載の方法。2. The method according to claim 1, wherein the ratio of Si / Mn in the molten metal and the oxygen concentration in the inert atmosphere of the pool are determined by the following:
2. The method according to claim 1, wherein the deposition temperature of the oxide composition that is deposited first when the temperature drops is adjusted.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP4099190A JP2809464B2 (en) | 1990-02-23 | 1990-02-23 | Continuous casting of thin cast slab |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP4099190A JP2809464B2 (en) | 1990-02-23 | 1990-02-23 | Continuous casting of thin cast slab |
Publications (2)
| Publication Number | Publication Date |
|---|---|
| JPH03248747A JPH03248747A (en) | 1991-11-06 |
| JP2809464B2 true JP2809464B2 (en) | 1998-10-08 |
Family
ID=12595898
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| JP4099190A Expired - Fee Related JP2809464B2 (en) | 1990-02-23 | 1990-02-23 | Continuous casting of thin cast slab |
Country Status (1)
| Country | Link |
|---|---|
| JP (1) | JP2809464B2 (en) |
Families Citing this family (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| FR2762534B1 (en) * | 1997-04-29 | 1999-05-28 | Usinor | CONTINUOUS CASTING INSTALLATION OF METAL STRIPS BETWEEN TWO CYLINDERS |
| KR100368278B1 (en) * | 1997-12-26 | 2003-03-17 | 주식회사 포스코 | Apparatus for preventing scum entrappment in strip casting |
| US20040144518A1 (en) * | 2003-01-24 | 2004-07-29 | Blejde Walter N. | Casting steel strip with low surface roughness and low porosity |
-
1990
- 1990-02-23 JP JP4099190A patent/JP2809464B2/en not_active Expired - Fee Related
Also Published As
| Publication number | Publication date |
|---|---|
| JPH03248747A (en) | 1991-11-06 |
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| LAPS | Cancellation because of no payment of annual fees |