JP2007260741A - Method of starting continuous casting of molten steel - Google Patents

Method of starting continuous casting of molten steel Download PDF

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JP2007260741A
JP2007260741A JP2006091016A JP2006091016A JP2007260741A JP 2007260741 A JP2007260741 A JP 2007260741A JP 2006091016 A JP2006091016 A JP 2006091016A JP 2006091016 A JP2006091016 A JP 2006091016A JP 2007260741 A JP2007260741 A JP 2007260741A
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molten steel
continuous casting
tundish
gas
insertion hole
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JP4923672B2 (en
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Tetsuya Sugawara
哲也 菅原
Kazuhiro Kariya
和宏 仮屋
Yuki Nabeshima
祐樹 鍋島
Seiichi Wakayanagi
誠一 若柳
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JFE Steel Corp
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Abstract

<P>PROBLEM TO BE SOLVED: To provide a method of starting continuous casting of molten steel which can prevent relatively easily air oxidation of a metal component in molten steel during a period from a time immediately after starting the injection from a ladle to a tundish to an early stage of starting the injection. <P>SOLUTION: The method of starting continuous casting of molten steel includes: preheating the atmosphere inside the tundish by a preheating gas/burner; once performing gas exchange by introduction of inert gas; charging a combustible substance from an insertion hole for a long/nozzle or the gap in the periphery of the long/nozzle to burn the combustible substance; consuming oxygen in the insertion hole and inside atmosphere; and sealing the insertion hole with a combustion product gas, and at the same time, lowering the oxygen concentration of the inside atmosphere quickly. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

本発明は、溶鋼の連続鋳造開始方法に係わり、特に、ステンレス鋼の連続鋳造において、鋳造開始当初の溶鋼で製造される鋳片の品質を向上させるのに有効な技術に関する。   The present invention relates to a method for starting continuous casting of molten steel, and more particularly to a technique effective in improving the quality of a slab produced from molten steel at the beginning of casting in continuous casting of stainless steel.

溶鋼の連続鋳造は、一般に以下のように行われる。まず、図４に示すように、精錬が終了し、取鍋１に出鋼した溶鋼２を、ノズル３を介して一旦タンディッシュ４と称する中間容器に滞留させてから、鋳型５へ連続的に注入する。引き続き、鋳型５内で凝固を開始し、外殻を形成した半凝固体６は、ゆっくりとした速度（通常、０．７〜１．５ｍ／ｍｉｎ程度の引き抜き速度）で下方に引き抜かれ、水冷された一群のロール７からなる冷却帯８を通過し、完全な凝固体となる。その後、該凝固体は、ガス・トーチ９等で所定の長さに切断され、スラブ、ブルーム等と称される鋼鋳片１０となる。   The continuous casting of molten steel is generally performed as follows. First, as shown in FIG. 4, after refining is completed, the molten steel 2 that has been delivered to the ladle 1 is once retained in an intermediate container called a tundish 4 through a nozzle 3 and then continuously into the mold 5. inject. Subsequently, the semi-solid body 6 that has started to solidify in the mold 5 and formed an outer shell is drawn downward at a slow speed (usually about 0.7 to 1.5 m / min), and water-cooled. It passes through the cooling zone 8 composed of a group of rolls 7 and becomes a complete solidified body. Thereafter, the solidified body is cut into a predetermined length by a gas torch 9 or the like to become a steel slab 10 called slab, bloom or the like.

このような溶鋼の連続鋳造において、上記の取鍋と鋳型との間に配置されたタンディッシュは、鋳型へ供給する溶鋼量のコントロール、溶鋼の均一化、非金属介在物の分離除去等の機能を有し、連続鋳造の操業及び得られる鋼鋳片の品質に大きな影響を与える装置である。特に、ステンレス鋼材品質に厳格な近年では、その非金属介在物の分離除去は、重要な機能となる。   In such continuous casting of molten steel, the tundish placed between the ladle and the mold has functions such as controlling the amount of molten steel supplied to the mold, homogenizing the molten steel, and separating and removing non-metallic inclusions. And has a great influence on the operation of continuous casting and the quality of the steel slab obtained. In particular, in recent years when the quality of stainless steel materials is strict, the separation and removal of non-metallic inclusions is an important function.

一方、取鍋からタンディッシュヘ注入開始した直後の溶鋼は、注入流が巻き込む大気（空気中の酸素）やタンディッシュ内雰囲気の残留酸素と、式（１）や式（２）で示すような反応を起こし、該溶鋼が含有する金属成分が酸化され、非金属介在物を生ずる。
２［Ａ１］＋３Ｏ→（Ａｌ２Ｏ３）…… 式（１）
［Ｓｉ］＋２Ｏ→（ＳｉＯ２）…… 式（２）
ここで、［ ］は溶鋼中の成分、（ ）は非金属介在物であることを表している。

このような非金属介在物で汚染された溶鋼が鋳型に注入されると、鋳造開始初期に得られる鋼鋳片の品質は著しく低下するばかりでなく、その一部はスクラップとして切捨てられることとなり、品質や製品歩留りの観点から好ましくない。つまり、連続鋳造初期の溶鋼の酸化防止は、操業上での解決すべき重要な課題の一つになる。 On the other hand, the molten steel immediately after the start of pouring into the tundish from the ladle is the atmosphere (oxygen in the air) in which the pouring flow is involved, the residual oxygen in the atmosphere in the tundish, and the equations (1) and (2) A reaction occurs, and the metal component contained in the molten steel is oxidized to produce non-metallic inclusions.
2 [A1] + 3O → (Al 2 O 3 ) (1)
[Si] + 2O → (SiO 2 ) (2)
Here, [] represents a component in molten steel, and () represents a non-metallic inclusion.

When molten steel contaminated with such non-metallic inclusions is poured into the mold, the quality of the steel slab obtained at the beginning of casting not only significantly decreases, but part of it will be discarded as scrap, This is not preferable from the viewpoint of quality and product yield. In other words, prevention of oxidation of molten steel at the initial stage of continuous casting is one of the important issues to be solved in operation.

そこで、従来から様々な対策が検討され、公開されている技術も多い。例えば、図３に示すように、タンディッシュ４内を耐火ボード(破線で示す)にて上下に二分し、下側の部屋を不活性ガスで満たしてから、取鍋に取り付けられ、先端が該下側の部屋まで届く所謂「ロング・ノズル」を介して、取鍋１内の溶鋼２をタンディッシュ４へ注入することで、溶鋼の空気酸化の防止を図る技術がある（特許文献１参照）。また、鋳込み初期に取鍋１からタンディッシュ４へ溶鋼２を注入するに際し、該タンディッシュ４内の湯面上昇速度を４０ｃｍ／分以上に限定することで、注入流落口での気泡巻き込み量を低減する技術も公開されている（特許文献２参照）。さらに、取鍋１からタンディッシュ４に溶鋼２を注入する際に、ロング・ノズル３内にカルシウム合金あるいはＣａＯ系フラックスを吹き込むことで、非金属介在物の吸着除去を図る技術も提案されている（特許文献３参照）。さらに加えて、タンデッシュ内に溶融性保温剤を供給すると共に、ＣａＯ系フラックスを添加する技術もある（特許文献４参照）。
特開昭５９−１０５５号公報 特開昭６０−２６１６５１号公報 特開昭６１−３８７４９号公報 特開平７−５１８１４号公報 Therefore, various countermeasures have been studied and many techniques have been disclosed. For example, as shown in FIG. 3, the inside of the tundish 4 is divided into two vertically by a fireproof board (shown by a broken line), the lower chamber is filled with an inert gas, and then attached to a ladle, and the tip is There is a technique for preventing air oxidation of molten steel by injecting molten steel 2 in a ladle 1 into a tundish 4 through a so-called “long nozzle” that reaches a lower room (see Patent Document 1). . Moreover, when pouring the molten steel 2 from the ladle 1 to the tundish 4 at the initial stage of casting, the amount of bubbles entrained at the pouring spout is limited by limiting the rising speed of the molten metal surface in the tundish 4 to 40 cm / min or more The technology to reduce is also disclosed (see Patent Document 2). Furthermore, when pouring molten steel 2 from the ladle 1 into the tundish 4, a technique for adsorbing and removing nonmetallic inclusions by blowing a calcium alloy or CaO-based flux into the long nozzle 3 has also been proposed. (See Patent Document 3). In addition, there is a technique for supplying a melt heat-retaining agent into the tundish and adding a CaO-based flux (see Patent Document 4).
JP 59-1055 A JP-A-60-261651 JP 61-38749 A JP-A-7-51814

しかしながら、特許文献１記載の技術には、せっかく耐火物ボードを使用しても、ボード自体の熱変形により空気の侵入は完全に防げないばかりでなく、耐火物ボート費用によるコストアップがあり、経済的に不利になるという問題もある。また、構造上、蓋のシールが十分でないので、タンディッシュ内へ不活性ガスを導入しても、雰囲気を不活性ガスで完全に置換しきれないし、置換ガス自体の熱対流により空気が巻き込まれるという問題もあった。さらに、特許文献２記載の技術では、タンディッシュ内の湯面上昇速度を４０ｃｍ／分以上に限定する具体的な手段が明記されていないので、有効な手段の選択ができないという問題がある。加えて、特許文献３及び４に記載されたロング・ノズルやタンディッシュヘのＣａＯ系フラックスの添加技術では、未溶融又は溶融した該フラックスがタンディッシュ内にて十分に溶鋼と分離されずに鋳型内に侵入し、鋼鋳片に捕捉され、非金属介在物に加わるという可能性がある。   However, in the technology described in Patent Document 1, even if a refractory board is used, not only air intrusion cannot be completely prevented due to thermal deformation of the board itself, but also there is an increase in cost due to refractory boat cost, There is also the problem of becoming disadvantageous. Also, because the lid seal is not sufficient due to the structure, even if an inert gas is introduced into the tundish, the atmosphere cannot be completely replaced with the inert gas, and air is entrained by the thermal convection of the replacement gas itself. There was also a problem. Furthermore, the technique described in Patent Document 2 has a problem that an effective means cannot be selected because a specific means for limiting the rising speed of the molten metal surface in the tundish to 40 cm / min or more is not specified. In addition, in the addition technique of the CaO-based flux to the long nozzle or tundish described in Patent Documents 3 and 4, the unmelted or melted flux is not sufficiently separated from the molten steel in the tundish, and the mold There is a possibility that it penetrates inside, is captured by the steel slab, and joins non-metallic inclusions.

このように、タンディッシュへ注入開始した直後の溶鋼は、空気酸化されたり、あるいは添加されたフラックスを巻き込むため、鋳造開始初期に製造された鋼鋳片は、後に製造された鋼鋳片に比し、品質が低いという問題点があったのである。   As described above, since the molten steel immediately after the start of pouring into the tundish is oxidized by air or entrains the added flux, the steel slab manufactured at the beginning of casting is compared with the steel slab manufactured later. However, there was a problem that the quality was low.

本発明は、かかる事情に鑑み、取鍋からタンディッシュへの注入開始直後から注入開姶初期の溶鋼中金属成分の空気酸化を、比較的簡便に防止可能な溶鋼の連続鋳造開始方法を提供することを目的としている。   In view of such circumstances, the present invention provides a method for starting continuous casting of molten steel that can relatively easily prevent air oxidation of metal components in molten steel immediately after the start of pouring from a ladle into a tundish at the beginning of pouring. The purpose is that.

発明者は、上記目的を達成するため鋭意研究を重ね、その成果を本発明に具現化した。   The inventor has intensively studied to achieve the above object, and the results have been embodied in the present invention.

すなわち、本発明は、溶鋼を保持した取鍋と該溶鋼を連続鋳造する鋳型との間に配置され、予熱ガス・バーナ用開口、不活性ガス導入用開口、試料サンプリング用開口及び取鍋に取り付けたロング・ノズルの挿入孔を有する蓋を備えたタンディッシュに、前記取鍋より溶鋼を注入開始するに際して、前記タンディッシュ内の雰囲気を前記予熱ガス・バーナで予熱すると共に、不活性ガスの導入で一旦ガス置換を行い、取鍋内溶鋼を注入開始する前又は直後に、燃焼性物質を前記ロング・ノズルの挿入孔又は該ロング・ノズル周囲の隙間より投入し、該燃焼性物質を燃焼させ、前記挿入孔及び内部雰囲気中の酸素を消費し、該挿入孔をその燃焼生成ガスによってシールすると同時に、内部雰囲気の酸素濃度を迅速に低下させることを特徴とする溶鋼の連続鋳造開始方法である。   That is, the present invention is arranged between a ladle holding molten steel and a mold for continuously casting the molten steel, and is attached to a preheating gas / burner opening, an inert gas introduction opening, a sample sampling opening, and a ladle. When injecting molten steel from the ladle into a tundish having a lid with a long nozzle insertion hole, the atmosphere in the tundish is preheated with the preheating gas burner and an inert gas is introduced. Before or immediately after injecting molten steel in the ladle, the combustible material is introduced through the insertion hole of the long nozzle or the gap around the long nozzle to burn the combustible material. The oxygen in the insertion hole and the internal atmosphere is consumed, and the insertion hole is sealed by the combustion product gas, and at the same time, the oxygen concentration in the internal atmosphere is rapidly reduced. It is a continuous casting start method of steel.

この場合、前記燃焼性物質の投入を、前記ロング・ノズルの挿入孔又は該ロング・ノズル周囲の隙間に代え、封鎖前のバーナ用開口、不活性ガス導入用開口、試料サンプリング用開口から行っても良い。また、前記燃焼性物質が粉粒状の炭素含有物質であったり、あるいは前記燃焼性物質を溶鋼の保温材料と混合し、その混合物を投入しても良い。さらに、前記燃焼性物質の投入量を、図５に示すように、前記ガス置換するタンディッシュの体積当たり０．５〜１０ｋｇ／ｍ３としたり、あるいは前記溶鋼がステンレス溶鋼とするのが好ましい。 In this case, the combustible substance is charged by replacing the long nozzle insertion hole or the gap around the long nozzle through the burner opening, the inert gas introduction opening, and the sample sampling opening before blocking. Also good. Further, the combustible substance may be a granular carbon-containing substance, or the combustible substance may be mixed with a heat insulating material of molten steel and the mixture may be charged. Further, as shown in FIG. 5, it is preferable that the amount of the combustible material introduced is 0.5 to 10 kg / m 3 per volume of the tundish to be replaced with gas, or the molten steel is stainless molten steel.

本発明では、取鍋内の溶鋼をタンディッシュへ注入開始する前に、予めタンディッシュ内の雰囲気から酸素をほぼ除去できるようになる。その結果、連続鋳造の開始直後あるいは初期に製造された鋼鋳片に含まれる非金属介在物の量が格段に低減し、品質及び溶鋼歩留りが従来に比し向上する。   In the present invention, oxygen can be substantially removed from the atmosphere in the tundish in advance before the molten steel in the ladle is poured into the tundish. As a result, the amount of non-metallic inclusions contained in the steel slab produced immediately after the start of continuous casting or in the initial stage is remarkably reduced, and the quality and molten steel yield are improved as compared with the prior art.

以下、発明をなすに至った経緯をまじえ、本発明の最良の実施形態を説明する。   Hereinafter, the best embodiment of the present invention will be described based on the background of the invention.

まず、発明者は、従来技術で、取鍋内の溶鋼をタンディッシュへ注入開始する前に、予めタンディッシュ内を上下で二分し、下方の雰囲気に不活性ガスを導入し、酸素を除去したにもかかわらず、鋳造初期に製造した鋼鋳片が非金属介在物の多い原因を追究した。その結果、図３に示したように、タンディッシュ４は蓋１１を備えているが、予熱ガス・バーナ用開口１２、不活性ガス導入用開口１３、試料サンプリング用開口１４及び取鍋に取り付けたロング・ノズル３の挿入孔１５等、開口部が多過ぎるので、ガス置換だけでは酸素が残留していたり、新たに侵入するためと考えた。   First, the inventor in the prior art, before starting to inject molten steel in the ladle into the tundish, the inside of the tundish was preliminarily divided into upper and lower parts, an inert gas was introduced into the lower atmosphere, and oxygen was removed. Nevertheless, the steel slabs manufactured in the early stages of casting investigated the causes of many nonmetallic inclusions. As a result, as shown in FIG. 3, the tundish 4 is provided with a lid 11, which is attached to the preheating gas / burner opening 12, the inert gas introduction opening 13, the sample sampling opening 14 and the ladle. Since there are too many openings such as the insertion hole 15 of the long nozzle 3, it is considered that oxygen remains or only newly enters by gas replacement.

そして、引き続きその対策を鋭意検討し、予め不活性ガスで雰囲気内のガス置換をした後、溶鋼をタンディッシュに注入開始するに際して、その前後に残留酸素や侵入酸素を燃焼させれば良いと考えた。具体的には、不活性ガスの導入及び予熱を停止し、タンディッシュの蓋にある全ての開口部を塞いで溶鋼を注入開始した後、直ちに高温のタンディッシュ４内に燃焼性物質を投入し、自発的に着火、燃焼させたり、あるいは溶鋼を注入開始する前の不活性ガスの導入及び予熱中に、燃焼性物質を投入する。つまり、残留酸素等の消滅と燃焼で発生した排ガスで前記ロング・ノズル３の挿入孔１５をシールとを同時に行うようにしたのである。   Then, after continually studying the countermeasures, after replacing the atmosphere in the atmosphere with an inert gas in advance, when starting the injection of molten steel into the tundish, it is considered that residual oxygen and intrusion oxygen should be burned before and after that. It was. Specifically, the introduction and preheating of the inert gas is stopped, all the openings in the tundish lid are closed, and molten steel is injected, and immediately after that, a combustible substance is introduced into the hot tundish 4. A flammable substance is introduced during the introduction and preheating of an inert gas before spontaneously igniting, burning, or injecting molten steel. In other words, the insertion hole 15 of the long nozzle 3 is sealed simultaneously with the disappearance of residual oxygen or the like and the exhaust gas generated by combustion.

そこで、実際の操業において雰囲気中の酸素濃度を実測しながら、燃焼性物質に「焼きもみ」を採用し、酸素濃度（容量％）の変化を確認した。その結果の一例を、作業手順に対応させて図１に示す。なお、図１の「置換開始」とは、不活性ガスの導入開始を、「Ｌ／Ｄ注入開始」とは、取鍋より溶鋼をタンディッシュへ注入開始を、「注湯開始」とはタンディッシュから鋳型への注入開始を、「鋳造開始」とは、鋳片の引き抜きの開始を、「サンプル孔Ａｒ停止」とは、不活性ガスの導入停止を、「サンプル孔フラックス投入」とは、サンプル孔より溶鋼の表面を多い、温度低下を防止する保温材料の投入を、「開口部ボードで塞ぐ」とは、蓋に設けられた全ての開口部をボードで覆う閉塞を、「焼きもみ投入」とは、本発明に係る燃焼性物質のタンディッシュ内への投入を、それぞれ意味している。   Therefore, while actually measuring the oxygen concentration in the atmosphere during actual operation, we adopted “baked rice cake” as a combustible substance and confirmed the change in oxygen concentration (volume%). An example of the result is shown in FIG. 1 corresponding to the work procedure. In FIG. 1, “replacement start” refers to the start of introduction of inert gas, “L / D injection start” refers to the start of pouring molten steel from the ladle into the tundish, and “pour start” refers to the start of The start of injection from the dish to the mold, “Casting start” means the start of drawing of the slab, “Sample hole Ar stop” means the introduction stop of inert gas, and “Sample hole flux injection” means Putting heat insulation material that has more molten steel surface than sample holes to prevent temperature drop, “Closing with opening board” means closing all openings provided in the lid with board. "Means the introduction of the combustible substance according to the present invention into the tundish, respectively.

図１より、タンディッシュ内の雰囲気は、溶鋼の注入開始後、巻き込んだ空気により一旦酸素濃度が上昇し、その後、不活性ガスの置換によって徐々に低下していくことが明らかである。発明法では、この時点でさらに前記ロング・ノズルとその挿入孔との隙間より燃焼性物質を投入し、該挿入孔の周囲及び内部雰囲気中の酸素を燃焼させるので、酸素濃度の低下速度が速まっている。   From FIG. 1, it is clear that the atmosphere in the tundish is once increased in oxygen concentration by the entrained air after the start of pouring of the molten steel, and then gradually lowered by replacement with the inert gas. In the invention method, at this time, a combustible substance is further introduced through the gap between the long nozzle and the insertion hole, and oxygen in the atmosphere around the insertion hole and in the internal atmosphere is combusted. waiting.

本発明では、燃焼物質の投入を、前記ロング・ノズルの挿入孔又は該ロング・ノズル周囲の隙間に代え、封鎖前のバーナ用開口、不活性ガス導入用開口、試料サンプリング用開口のいずれから行っても良い。要するに溶鋼を覆うようにすれば良いからである。   In the present invention, the combustion substance is charged from any one of the opening for burner, the opening for introducing inert gas, and the opening for sample sampling before sealing, instead of the insertion hole of the long nozzle or the gap around the long nozzle. May be. In short, it is only necessary to cover the molten steel.

また、本発明では、前記燃焼性物質としては特に限定しないが、比較的低温で着火し易い粉粒状（好ましくは、粒径０．５〜１０ｍｍ）の炭素含有物質を使用するのが良い。本発明では、一般的な「焼きもみ」及び／又は「加炭材」を使用して効果を確認した。０．５ｍｍ未満では、大気に中に飛散してロスになる可能性が大きいし、１０ｍｍ超えでは燃焼速度が遅くなるからである。さらに、該燃焼性物質は、溶鋼の保温材料と混合して投入しても良い。保温材料の保温効果促進に役立つからである。保温材料としては、公知のタンディッシュ・フラックスが利用できる。加えて、本発明では、燃焼性物質の投入量を、ガス置換するタンディッシュ体積当たり０．５〜１０ｋｇ／ｍ３の範囲とするのが好ましい。０．５ｋｇ／ｍ３未満では、酸素の燃焼が不十分で酸素濃度の低下が起きないし、１０ｋｇ／ｍ３超えでは効果が飽和し、添加が無駄になるからである。 In the present invention, the combustible substance is not particularly limited, but it is preferable to use a carbon-containing substance that is easily ignited at a relatively low temperature (preferably, a particle diameter of 0.5 to 10 mm). In the present invention, the effect was confirmed using a general “baked rice” and / or “carburized material”. If it is less than 0.5 mm, there is a high possibility that it will be lost in the atmosphere, and if it exceeds 10 mm, the combustion speed will be slow. Further, the combustible material may be mixed with a heat insulating material of molten steel and added. This is because it helps to promote the heat retaining effect of the heat retaining material. A known tundish flux can be used as the heat insulating material. In addition, in the present invention, it is preferable that the amount of the flammable substance input is in the range of 0.5 to 10 kg / m 3 per tundish volume for gas replacement. If it is less than 0.5 kg / m 3 , the combustion of oxygen is insufficient and the oxygen concentration does not decrease, and if it exceeds 10 kg / m 3 , the effect is saturated and the addition is wasted.

なお、図１の例では、燃焼性物質の投入時期を「Ｌ／Ｄ注入開始」後、つまり取鍋より溶鋼をタンディッシュへ注入開始した後としているが、開始前としても良い。燃焼性物質の投入量は増加するが、酸素濃度の低下効果が大きいからである。また、本発明の対象とする溶鋼も、特に鋼種を限定するものではない。ただし、本発明の性質上、ステンレス鋼等、含有する合金成分の多い鋼種ほど効果が大きい。   In addition, in the example of FIG. 1, although the injection | throwing-in timing of a combustible substance is after "L / D injection start", ie, after injecting molten steel into a tundish from a ladle, it may be before the start. This is because the amount of the combustible substance increases, but the effect of lowering the oxygen concentration is great. Further, the molten steel targeted by the present invention is not particularly limited to the steel type. However, due to the nature of the present invention, the higher the effect, the higher the steel type that contains more alloy components, such as stainless steel.

ＳＵＳ ４３０からなる溶鋼を取鍋に受け入れ、図４に示した湾曲型連続鋳造機を用い、一片のサイズが長さ８０００ｍｍ×幅１３００ｍｍ×厚さ２２０ｍｍの鋼鋳片（スラブ）を鋳造した。その際、本発明に係る溶鋼の連続鋳造開始方法を適用し、図１で説明したと同様の時期に、タンディッシュ内に燃焼性物質を投入した。 A molten steel made of SUS 430 was taken into a ladle and a steel slab (slab) having a size of 8000 mm long × 1300 mm wide × 220 mm thick was cast using the curved continuous casting machine shown in FIG. At that time, the method for initiating continuous casting of molten steel according to the present invention was applied, and a combustible substance was introduced into the tundish at the same time as described with reference to FIG.

そして、［焼きもみ］の投入後の時期にタンディッシュ内溶鋼のサンプルを採取し、該サンプル中の酸素濃度を測定することで投入効果を評価した。図２より明らかなように、タンディッシュ内溶鋼の酸素濃度は、燃焼性物質を投入しない従来例に比べ、大幅に低減している。また、この溶鋼を鋳造して得た鋼鋳片の非金属介在物量を調査したところ、鋳造後期の鋼鋳片と同程度で、製品としての合格基準を満足していた。つまり、本発明の適用で、所謂「連々鋳」の１チャージ目の溶鋼歩留り（鋳造に供した溶鋼の質量に対する合格基準を満たした鋼鋳片の質量総和との比率）が従来の９５％から９７％へと大幅に向上した。   Then, a sample of molten steel in the tundish was collected at a time after the introduction of [baked rice], and the effect of the addition was evaluated by measuring the oxygen concentration in the sample. As apparent from FIG. 2, the oxygen concentration of the molten steel in the tundish is greatly reduced as compared with the conventional example in which no flammable substance is introduced. Further, when the amount of non-metallic inclusions in the steel slab obtained by casting this molten steel was investigated, it was the same as the steel slab in the latter stage of casting and satisfied the acceptance criteria as a product. That is, by applying the present invention, the so-called “continuous casting” first-charge molten steel yield (ratio with the total mass of steel slabs that satisfy the acceptance criteria with respect to the mass of molten steel subjected to casting) is 95% of the conventional value. It improved significantly to 97%.

本発明に係る溶鋼の鋳造開始方法の手順とタンディッシュ内雰囲気の酸素濃度の変化例を示す図である。It is a figure which shows the procedure of the casting start method of the molten steel which concerns on this invention, and the example of a change of the oxygen concentration of the atmosphere in a tundish. 本発明の実施効果を示す図である。It is a figure which shows the implementation effect of this invention. 一般的なタンディッシュの構成を示す横断面図である。It is a cross-sectional view which shows the structure of a general tundish. 溶鋼の連続鋳造を説明する図である。It is a figure explaining continuous casting of molten steel. タンディッシュ内雰囲気の酸素濃度と燃焼物質の投入量との関係を示す図である。It is a figure which shows the relationship between the oxygen concentration of the atmosphere in a tundish, and the injection amount of a combustion substance.

符号の説明Explanation of symbols

１ 取鍋
２ 溶鋼
３ ノズル（ロング・ノズル）
４ タンディッシュ
５ 鋳型
６ 半凝固体
７ ロール
８ 冷却帯
９ ガス・トーチ
１０ 鋼鋳片
１１ 蓋
１２ 予熱ガス・バーナ用開口
１３ 不活性ガス導入用開口
１４ 試料サンプリング用開口
１５ ロング・ノズルの挿入孔 1 Ladle 2 Molten Steel 3 Nozzle (Long Nozzle)
4 Tundish 5 Mold 6 Semi-solid body 7 Roll 8 Cooling zone 9 Gas torch 10 Steel slab 11 Lid 12 Preheated gas / burner opening 13 Inert gas introduction opening 14 Sample sampling opening 15 Long nozzle insertion hole

Claims (6)

溶鋼を保持した取鍋と該溶鋼を連続鋳造する鋳型との間に配置され、予熱ガス・バーナ用開口、不活性ガス導入用開口、試料サンプリング用開口及び取鍋に取り付けたロング・ノズルの挿入孔を有する蓋を備えたタンディッシュに、前記取鍋より溶鋼を注入開始するに際して、
前記タンディッシュ内の雰囲気を前記予熱ガス・バーナで予熱すると共に、不活性ガスの導入で一旦ガス置換を行い、取鍋内溶鋼を注入開始する前又は直後に、燃焼性物質を前記ロング・ノズルの挿入孔又は該ロング・ノズル周囲の隙間より投入し、該燃焼性物質を燃焼させ、前記挿入孔及び内部雰囲気中の酸素を消費し、該挿入孔をその燃焼生成ガスによってシールすると同時に、内部雰囲気の酸素濃度を迅速に低下させることを特徴とする溶鋼の連続鋳造開始方法。 Inserted into the ladle holding the molten steel and the mold for continuous casting of the molten steel, preheating gas / burner opening, inert gas introduction opening, sample sampling opening, and long nozzle attached to the ladle When starting to inject molten steel from the ladle into the tundish provided with a lid having a hole,
The atmosphere in the tundish is preheated with the preheating gas burner, and once the gas is replaced by introducing an inert gas, the combustible substance is introduced into the long nozzle before or immediately after the start of pouring of molten steel in the ladle. The insertion hole or the gap around the long nozzle is inserted to burn the combustible material, consume oxygen in the insertion hole and the internal atmosphere, and seal the insertion hole with the combustion product gas. A method for initiating continuous casting of molten steel, characterized by rapidly reducing the oxygen concentration in the atmosphere. 前記燃焼性物質の投入を、前記ロング・ノズルの挿入孔又は該ロング・ノズル周囲の隙間に代え、封鎖前のバーナ用開口、不活性ガス導入用開口、試料サンプリング用開口から行うことを特徴とする請求項１記載の溶鋼の連続鋳造開始方法。   The combustible substance is charged from the opening for burner, the opening for introducing inert gas, and the opening for sample sampling before sealing, in place of the insertion hole of the long nozzle or the gap around the long nozzle. The method for starting continuous casting of molten steel according to claim 1. 前記燃焼性物質が粉粒状の炭素含有物質であことを特徴とする請求項１又は２記載の溶鋼の連続鋳造開始方法。   The method for initiating continuous casting of molten steel according to claim 1 or 2, wherein the combustible substance is a granular carbon-containing substance. 前記燃焼性物質を溶鋼の保温材料と混合し、その混合物を投入することを特徴とする請求項１〜３のいずれかに記載の溶鋼の連続鋳造開始方法。   The method for initiating continuous casting of molten steel according to any one of claims 1 to 3, wherein the combustible substance is mixed with a heat insulating material of molten steel, and the mixture is charged. 前記燃焼性物質の投入量を、前記ガス置換するタンディッシュの体積当たり０．５〜１０ｋｇ／ｍ３とすることを特徴とする請求項１〜４のいずれかに記載の溶鋼の連続鋳造開始方法。 The input amount of the combustible material, the molten steel process of continuous casting start as claimed in any one of claims 1 to 4, characterized in that the tundish volume per 0.5 to 10 / m 3 of which the gas replacement . 前記溶鋼がステンレス溶鋼であることを特徴とする請求項１〜５のいずれかに記載の溶鋼の連続鋳造開始方法。

The said molten steel is stainless steel molten steel, The continuous casting start method of the molten steel in any one of Claims 1-5 characterized by the above-mentioned.

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CN113828748A (en) * 2020-06-23 2021-12-24 宝山钢铁股份有限公司 Automatic control system and method for preventing molten steel from being oxidized in whole continuous casting process
CN114746195A (en) * 2019-11-29 2022-07-12 杰富意钢铁株式会社 Method for casting molten steel, method for producing continuously cast slab, and method for producing steel for bearing

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* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN114746195A (en) * 2019-11-29 2022-07-12 杰富意钢铁株式会社 Method for casting molten steel, method for producing continuously cast slab, and method for producing steel for bearing
CN113828748A (en) * 2020-06-23 2021-12-24 宝山钢铁股份有限公司 Automatic control system and method for preventing molten steel from being oxidized in whole continuous casting process

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