JP2007111721A - Heat-retaining material for molten steel surface, and continuous casting method for steel using the same - Google Patents
Heat-retaining material for molten steel surface, and continuous casting method for steel using the same Download PDFInfo
- Publication number
- JP2007111721A JP2007111721A JP2005304210A JP2005304210A JP2007111721A JP 2007111721 A JP2007111721 A JP 2007111721A JP 2005304210 A JP2005304210 A JP 2005304210A JP 2005304210 A JP2005304210 A JP 2005304210A JP 2007111721 A JP2007111721 A JP 2007111721A
- Authority
- JP
- Japan
- Prior art keywords
- molten steel
- mass
- heat insulating
- insulating material
- steel surface
- 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.)
- Withdrawn
Links
Classifications
-
- Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
- Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
- Y02P—CLIMATE CHANGE MITIGATION TECHNOLOGIES IN THE PRODUCTION OR PROCESSING OF GOODS
- Y02P10/00—Technologies related to metal processing
- Y02P10/20—Recycling
Landscapes
- Continuous Casting (AREA)
- Treatment Of Steel In Its Molten State (AREA)
Abstract
Description
本発明は、連続鋳造用タンディッシュや取鍋などにより溶鋼を移送、又は精錬処理を行う際に、断熱・保温あるいは空気酸化防止を目的として溶鋼表面を被覆する溶鋼表面保温材およびそれを用いた連続鋳造方法に関するものである。 The present invention uses a molten steel surface heat insulating material that coats the molten steel surface for the purpose of heat insulation / heat retention or air oxidation prevention when the molten steel is transferred or refined by a tundish or ladle for continuous casting, and the like. The present invention relates to a continuous casting method.
連続鋳造用タンディッシュや取鍋などにより溶鋼を移送、又は精錬処理を行う際、保温材を用いて溶鋼表面を被覆し溶鋼からの熱放散と外気の溶鋼への侵入を防止している。従来から保温材として、籾殻を蒸し焼きにした焼籾が主に用いられ、その主成分はＳｉＯ2とＣである。ＳｉＯ2は熱伝導率が低く保温効果に、Ｃは酸素をＣＯガスに変えるため酸素の遮断効果に優れている。このため、焼籾は保温効果及び空気遮断効果を有し、しかも安価であることを特徴とする保温材である。しかしながら、加工性向上の目的から鋼板中のＣ濃度を極力低下させた、例えばＣ濃度が５０ｐｐｍ以下の極低炭素鋼において、保温材中のＣ成分が溶鋼中にピックアップされ、鋼材の特性を低下させる欠点が知られている。また、保温材中のＳｉＯ2成分は溶鋼中のＡｌと反応してＡｌ2Ｏ3系の介在物を生成するため、表面欠陥を増大させるといった問題も生じる。従来、焼籾のこれらの欠点を解決するため、Ｃ及びＳｉＯ2成分の少ない保温材として、例えば特許文献１に記載されているように、ＭｇＯ系の保温材が使用されている。また、ＭｇＯ自体は熱伝導率が高いため、これに断熱性を付与した発泡ＭｇＯの製造方法についても種々検討され、特許文献２等に記載されている。 When the molten steel is transferred or refined by a tundish for continuous casting or a ladle, the surface of the molten steel is covered with a heat insulating material to prevent heat dissipation from the molten steel and intrusion of outside air into the molten steel. Conventionally, shochu obtained by steaming rice husk is mainly used as a heat insulating material, and the main components are SiO 2 and C. SiO 2 has a low thermal conductivity and has a heat retention effect, and C has an excellent oxygen blocking effect because it converts oxygen to CO gas. For this reason, shochu is a heat insulating material characterized by having a heat insulating effect and an air blocking effect and being inexpensive. However, for the purpose of improving workability, the C concentration in the steel sheet has been reduced as much as possible, for example, in an extremely low carbon steel having a C concentration of 50 ppm or less, the C component in the heat insulating material is picked up in the molten steel, and the characteristics of the steel material are reduced. There are known drawbacks. Further, since the SiO 2 component in the heat insulating material reacts with Al in the molten steel to generate Al 2 O 3 -based inclusions, there is a problem of increasing surface defects. Conventionally, in order to solve these drawbacks of shochu, an MgO-based heat insulating material is used as a heat insulating material having a small amount of C and SiO 2 components, as described in Patent Document 1, for example. In addition, since MgO itself has a high thermal conductivity, various methods for producing foamed MgO imparted with heat insulation properties have been studied and described in Patent Document 2 and the like.
しかしながら、特許文献１や特許文献２のようなＭｇＯを主成分とする保温材は融点が高く、使用温度では主に粉末或いは焼結状の固相として存在しているため、溶鋼表面の均一な被覆状態が得られず、外気と溶鋼との反応によりＡｌ2Ｏ3系介在物を生成する。これに対し、ＭｇＯの一部をＳｉＯ2、Ｎａ2Ｏ、或いはＣａＦ2等の低融点化材に置き換えて保温材を溶融させ、溶鋼表面を均一に被覆する方法が考えられるが、この場合ＳｉＯ2やＮａ2Ｏは溶鋼中のＡｌと反応してＡｌ2Ｏ3系介在物を生成し、ＣａＦ2はタンディッシュ耐火物を溶損させることにより耐火物起因の介在物を増大させる。 However, since the heat insulating material mainly composed of MgO such as Patent Document 1 and Patent Document 2 has a high melting point and exists mainly as a powder or sintered solid phase at the operating temperature, the surface of the molten steel is uniform. A covering state cannot be obtained, and Al 2 O 3 inclusions are generated by the reaction between the outside air and molten steel. On the other hand, a method in which a part of MgO is replaced with a low melting point material such as SiO 2 , Na 2 O or CaF 2 to melt the heat insulating material and coat the molten steel surface uniformly is considered. 2 and Na 2 O react with Al in the molten steel to produce Al 2 O 3 inclusions, and CaF 2 increases the inclusion due to the refractory by melting the tundish refractory.
これらの問題を鑑み、本発明は空気酸化と保温材の反応に起因する溶鋼汚染を確実に防止できる保温材と、清浄性の優れた鋳片を得るための連続鋳造方法を提供することを目的とするものである。 In view of these problems, an object of the present invention is to provide a heat insulating material that can reliably prevent contamination of molten steel caused by the reaction between air oxidation and the heat insulating material, and a continuous casting method for obtaining a slab excellent in cleanliness. It is what.
上記課題を解決するために、本発明は以下に構成を要旨とする。即ち、
（１）溶鋼表面保温材において、ＳｉＯ2含有率を５質量％以下、ＣａＯ／Ａｌ2Ｏ3を質量比で１．１〜２．０、ＭｇＯ含有率を１０質量％以上３０質量％未満、且つＴｉを含有したことを特徴とする溶鋼表面保温材。
（２）溶鋼表面保温材において、ＳｉＯ2含有率を５質量％以下、ＣａＯ／Ａｌ2Ｏ3を質量比で１．１〜２．０、ＭｇＯ含有率を１０質量％以上３０質量％未満、且つＴｉとＴｉＯ2を含有したことを特徴とする溶鋼表面保温材。
（３）Ｔｉを０．１〜１０質量％含有していることを特徴とする請求項１記載の溶鋼表面保温材。
（４）Ｔｉを０．１〜１０質量％、ＴｉＯ2を２〜３０質量％含有していることを特徴とする請求項２記載の溶鋼表面保温材。
（５）鋼の連続鋳造方法において請求項１から４の何れかに記載の溶鋼表面保温材をタンディッシュ内の溶鋼表面上に添加することを特徴とする鋼の連続鋳造方法。
（６）鋼の連続鋳造方法において請求項１から４の何れかに記載の溶鋼表面保温材をタンディッシュ内のＴｉ脱酸溶鋼表面上に添加することを特徴とする鋼の連続鋳造方法。
In order to solve the above problems, the present invention is summarized as follows. That is,
(1) In the molten steel surface heat insulating material, the SiO 2 content is 5% by mass or less, CaO / Al 2 O 3 is 1.1 to 2.0 by mass ratio, and the MgO content is 10% by mass or more and less than 30% by mass, And the molten steel surface heat insulating material characterized by containing Ti.
(2) In the molten steel surface heat insulating material, the SiO 2 content is 5% by mass or less, CaO / Al 2 O 3 is 1.1 to 2.0 by mass ratio, and the MgO content is 10% by mass or more and less than 30% by mass, and the molten steel surface heat insulating material, characterized in that contained Ti and TiO 2.
(3) The molten steel surface heat insulating material according to claim 1, comprising 0.1 to 10% by mass of Ti.
(4) The molten steel surface heat insulating material according to claim 2 , comprising 0.1 to 10% by mass of Ti and 2 to 30% by mass of TiO 2 .
(5) In the continuous casting method of steel, the molten steel surface heat insulating material according to any one of claims 1 to 4 is added onto the molten steel surface in the tundish.
(6) A continuous casting method for steel, wherein the molten steel surface heat insulating material according to any one of claims 1 to 4 is added onto the Ti deoxidized molten steel surface in the tundish.
本発明の溶鋼表面保温材およびこの保温材を用いた連続鋳造方法によれば、溶鋼の汚染は軽減され、鋳造品質は極めて向上する。また、耐火物の溶損もなく、保温材の排滓性も向上するため、操業面でも有効な連続鋳造方法を提供できる。 According to the molten steel surface heat insulating material and the continuous casting method using the heat insulating material of the present invention, contamination of the molten steel is reduced and the casting quality is greatly improved. In addition, since the refractory is not melted and the heat insulating material is improved, the continuous casting method that is effective in terms of operation can be provided.
溶鋼表面を被覆する保温材として満足すべき条件は、溶鋼の保温性を確保した上で、空気酸化と保温材の反応に起因する溶鋼の汚染を確実に防止し、かつ、長時間使用できるようにタンディッシュ耐火物の溶損を防止することである。 Conditions that should be satisfied as a heat insulating material covering the surface of the molten steel are to ensure that the molten steel is kept warm, to reliably prevent contamination of the molten steel due to the reaction between the air oxidation and the heat insulating material, and to be able to be used for a long time. It is to prevent the tundish refractory from melting.
発明者らはこれら基本条件を満足すべく保温材の検討を進めた結果、保温材と溶鋼の反応を防止するためには低ＳｉＯ2化が、また空気酸化を抑制するためにはＣａＯ／Ａｌ2Ｏ3の質量比を適正化した上でＴｉを少量含有させることが、さらに、タンディッシュ耐火物の溶損を防止するためにはＭｇＯを添加することが有効であることを見いだした。 As a result of studying the heat insulating material to satisfy these basic conditions, the inventors have reduced SiO 2 to prevent the reaction between the heat insulating material and molten steel, and CaO / Al to suppress air oxidation. It has been found that it is effective to add a small amount of Ti after optimizing the mass ratio of 2 O 3 , and to add MgO to prevent the tundish refractory from melting.
保温材中のＳｉＯ2は［式１］と［式２］により溶鋼中のＡｌやＴｉと反応するため、保温材の低ＳｉＯ2化はＡｌ2Ｏ3系介在物やチタニア系介在物の生成防止の効果を有する。
３ＳｉＯ2＋４Ａｌ＝２Ａｌ2Ｏ3＋３Ｓｉ ［式１］
ＳｉＯ2＋Ｔｉ＝ＴｉＯ2＋Ｓｉ ［式２］
Since SiO 2 in the heat insulating material reacts with Al and Ti in the molten steel according to [Formula 1] and [Formula 2], reducing the heat insulating material to SiO 2 generates Al 2 O 3 inclusions and titania inclusions. Has the effect of prevention.
3SiO 2 + 4Al = 2Al 2 O 3 + 3Si [Formula 1]
SiO 2 + Ti = TiO 2 + Si [Formula 2]
本発明で規定のＣａＯ−Ａｌ2Ｏ3−ＭｇＯ成分系において保温材中のＳｉＯ2含有率が５質量％以下になると、［式１］と［式２］の反応速度は急速に低下し、実質的に生成するＡｌ2Ｏ3系介在物やチタニア系介在物が減少するため、ＳｉＯ2含有率を５質量％以下にする必要がある。ＳｉＯ2を全く含まなければ、［式１］と［式２］の反応は起こらないので、当然その下限値は０質量％を含む。 In the CaO—Al 2 O 3 —MgO component system defined in the present invention, when the SiO 2 content in the heat insulating material is 5% by mass or less, the reaction rates of [Formula 1] and [Formula 2] rapidly decrease, Since Al 2 O 3 -based inclusions and titania-based inclusions that are substantially generated are reduced, the SiO 2 content must be 5% by mass or less. If SiO 2 is not included at all, the reaction of [Formula 1] and [Formula 2] does not occur, so the lower limit value naturally includes 0% by mass.
また、タンディッシュ内溶鋼の空気酸化を防止するためには、保温材を低融点化し、溶鋼表面を保温材で均一に被覆することにより、溶鋼中への空気の侵入を遮断することが重要である。ＣａＯ−Ａｌ2Ｏ3系保温材を低融点化するためには、ＣａＯ／Ａｌ2Ｏ3を０．５〜２．０の範囲にする必要があり、ＣａＯ／Ａｌ2Ｏ3が０．５未満および２．０超の範囲では保温材の溶融温度が鋼の融点１５３６℃以上となり溶融し難いためである。なお、保温材の溶融温度は、１０ｍｍ直径×１０ｍｍ高さの保温材タブレットを加熱炉中で昇温し、保温材タブレットの高さが１／２になった際の温度とする。さらに、ＣａＯ−Ａｌ2Ｏ3系保温材中にＴｉを添加すると、部分的に保温材が未溶融状態である領域に侵入してきた酸素をＴｉがＴｉＯ2として固定するため、保温材溶融のばらつきまで考慮した上で確実に空気遮断することが可能となる。タンディッシュへの保温材投入は、手投げて実施されることが殆どであり、タンディッシュ内の場所により保温材厚みは均一でなく、溶融状態も一定ではないため、保温材へのＴｉ添加による酸素固定効果は保温材の空気遮断効果を大きく向上させる。 In order to prevent air oxidation of molten steel in the tundish, it is important to lower the melting point of the heat insulating material and to uniformly cover the surface of the molten steel with the heat insulating material, thereby blocking air intrusion into the molten steel. is there. In order to lower the melting point of the CaO—Al 2 O 3 heat insulating material, it is necessary to make CaO / Al 2 O 3 in the range of 0.5 to 2.0, and CaO / Al 2 O 3 is 0.5. If the temperature is less than or more than 2.0, the heat retaining material has a melting temperature of not less than 1536 ° C. of the steel and hardly melts. In addition, the melting temperature of the heat insulating material is set to a temperature when the temperature of the heat insulating material tablet having a diameter of 10 mm × 10 mm is raised in a heating furnace and the height of the heat insulating material tablet is halved. Furthermore, when Ti is added to the CaO-Al 2 O 3 heat insulating material, oxygen that has partially penetrated into the region where the heat insulating material is in an unmelted state is fixed as Ti TiO 2. It is possible to reliably shut off the air after considering the above. The heat insulating material is thrown into the tundish by hand, and the heat insulating material thickness is not uniform depending on the location in the tundish, and the molten state is not constant. The oxygen fixation effect greatly improves the air blocking effect of the heat insulating material.
上記組成のＴｉ含有ＣａＯ−Ａｌ2Ｏ3系保温材を用いて連続鋳造すると、ＣａＦ2添加の低融点保温材よりは耐火物溶損は軽減されるが、鋳造時間が長い場合、例えば２５０分を超えるような長時間鋳造時にはタンディッシュ耐火物溶損の問題は解決されないことが判明した。そこで、保温材を低融点化し、且つ鋳造時間が長い場合にもタンディッシュ耐火物を溶損させない成分条件を検討した結果、ＣａＯ／Ａｌ2Ｏ3を１．１〜２．０の範囲に縮小し、且つＭｇＯを１０質量％以上３０質量％未満含有させることが有効であることを見いだした。ＣａＯ／Ａｌ2Ｏ3を１．１未満と２．０超の範囲で、ＭｇＯが加わるとＴｉ含有ＣａＯ−ＭｇＯ−Ａｌ2Ｏ3系保温材の溶融温度が上昇し、タンディッシュ内で溶融しにくくなるため、ＣａＯ／Ａｌ2Ｏ3を１．１〜２．０にする必要がある。また、ＭｇＯが１０質量％未満では、２５０分を超える長時間鋳造でタンディッシュ耐火物の溶損が進行するため、またＭｇＯが３０質量％以上ではＴｉ含有ＣａＯ−ＭｇＯ−Ａｌ2Ｏ3液相中にＭｇＯが析出して保温材が一部凝固するため、ＭｇＯ含有率は１０質量％以上３０質量％未満にする必要がある。したがって、ＳｉＯ2含有率を５質量％以下、ＣａＯ／Ａｌ2Ｏ3を質量比で１．１〜２．０、ＭｇＯ含有率を１０質量％以上３０質量％未満、且つＴｉを含有した溶鋼表面保温材とすることにより、空気酸化、保温材と溶鋼との反応およびタンディッシュ耐火物の溶損に起因する溶鋼汚染を確実に防止できる。 When continuous casting is performed using the Ti-containing CaO—Al 2 O 3 type heat insulating material having the above composition, the refractory melt damage is reduced as compared with the CaF 2 added low melting point heat insulating material. It has been found that the problem of tundish refractory erosion cannot be solved when casting over a long time. Therefore, as a result of investigating the component conditions that do not cause the tundish refractory to melt even when the heat insulating material has a low melting point and the casting time is long, CaO / Al 2 O 3 is reduced to a range of 1.1 to 2.0. In addition, it has been found that it is effective to contain 10% by mass or more and less than 30% by mass of MgO. When CaO / Al 2 O 3 is less than 1.1 and more than 2.0 and MgO is added, the melting temperature of the Ti-containing CaO—MgO—Al 2 O 3 heat insulating material rises and melts in the tundish. to become Nikuku, it is necessary to the CaO / Al 2 O 3 on 1.1 to 2.0. Further, when MgO is less than 10% by mass, the tundish refractory is melted by casting for a long time exceeding 250 minutes, and when MgO is 30% by mass or more, a Ti-containing CaO—MgO—Al 2 O 3 liquid phase. Since MgO precipitates therein and the heat insulating material partially solidifies, the MgO content needs to be 10% by mass or more and less than 30% by mass. Therefore, the molten steel surface containing SiO 2 content of 5% by mass or less, CaO / Al 2 O 3 by mass ratio of 1.1 to 2.0, MgO content of 10% by mass to less than 30% by mass, and containing Ti. By using the heat insulating material, it is possible to reliably prevent molten steel contamination caused by air oxidation, reaction between the heat insulating material and the molten steel, and melting of the tundish refractory.
保温材中にＴｉを添加すると空気と反応してＴｉＯ2を生成するため、鋳造初期を除いてＴｉ含有ＣａＯ−ＭｇＯ−Ａｌ2Ｏ3系保温材中にはＴｉＯ2が含有される。ＴｉＯ2は保温材の粘性を低下させ、溶鋼表面上での保温材の広がり性を向上させるため、より均一な保温材被覆状態が得られ易くなる。このため、ＣａＯ−ＭｇＯ−Ａｌ2Ｏ3を主成分（合計で５０％以上を目安）とするＴｉ含有の保温材中に予めＴｉＯ2を含有させておくと、鋳造初期からＴｉＯ2の低粘性化効果により保温材の被覆性が向上する。 When Ti is added to the heat insulating material, it reacts with air to generate TiO 2, and thus the Ti-containing CaO—MgO—Al 2 O 3 heat insulating material contains TiO 2 except in the initial stage of casting. Since TiO 2 lowers the viscosity of the heat insulating material and improves the spreadability of the heat insulating material on the molten steel surface, it becomes easier to obtain a more uniform heat insulating material coating state. For this reason, if TiO 2 is contained in advance in a Ti-containing heat insulating material containing CaO—MgO—Al 2 O 3 as a main component (50% or more in total), the low viscosity of TiO 2 from the beginning of casting. The covering effect of the heat insulating material is improved by the effect of the heat treatment.
ＣａＯ−ＭｇＯ−Ａｌ2Ｏ3系保温材へのＴｉの好ましい添加範囲は０．１〜１０質量％である。Ｔｉの含有率が０．１質量％未満では空気中の酸素と反応し難く、反対に１０質量％超では溶鋼中にＴｉが一部溶解し、溶鋼中でのＴｉ濃度上昇やチタニア系介在物生成を引き起こすためである。 The preferable addition range of Ti to the CaO—MgO—Al 2 O 3 heat insulating material is 0.1 to 10% by mass. If the Ti content is less than 0.1% by mass, it is difficult to react with oxygen in the air. Conversely, if it exceeds 10% by mass, Ti partially dissolves in the molten steel, and the Ti concentration in the molten steel increases and titania inclusions. This is to cause generation.
また、ＣａＯ−ＭｇＯ−Ａｌ2Ｏ3を主成分とするＴｉ含有保温材へのＴｉＯ2の好ましい添加範囲は２．０〜３０質量％である。ＴｉＯ2の含有率が２質量％未満ではＴｉ−ＣａＯ−Ａｌ2Ｏ3系保温材の粘性が低下し難く、反対に３０質量％超では溶鋼中のＡｌとＴｉＯ2が反応してＡｌ2Ｏ3系介在物を少量ではあるが生成し易いためである。 Also preferred range of addition of the TiO 2 to Ti-containing heat insulating material composed mainly of CaO-MgO-Al 2 O 3 is 2.0 to 30 mass%. When the content of TiO 2 is less than 2% by mass, the viscosity of the Ti—CaO—Al 2 O 3 heat insulating material is difficult to decrease, whereas when it exceeds 30% by mass, Al in the molten steel reacts with TiO 2 to react with Al 2 O. This is because it is easy to produce a 3 system inclusion although it is a small amount.
保温材の基本組成は以上に述べた通りであるが、本発明品の機能を低下させない範囲であれば、ＺｒＯ2等の他の酸化物やＣａＣｌ2等の非酸化物を添加することも可能である。 The basic composition of the heat insulating material is as described above, but other oxides such as ZrO 2 and non-oxides such as CaCl 2 can be added as long as the function of the product of the present invention is not deteriorated. It is.
本発明の保温材はＣａＯ原料、Ａｌ2Ｏ3原料、ＴｉＯ2原料、Ｔｉ原料等を本発明で規定の成分となるように配合し、均一に混じるように混錬することにより製造される。 The heat insulating material of the present invention is produced by blending a CaO raw material, an Al 2 O 3 raw material, a TiO 2 raw material, a Ti raw material or the like so as to become the specified components in the present invention and kneading them so as to be uniformly mixed.
本発明の保温材をタンディッシュ内の溶鋼表面上に添加して鋼の連続鋳造を行うと、空気酸化と、保温材と溶鋼との反応に起因する溶鋼汚染を確実に防止でき、その上でタンディッシュ耐火物の溶損も生じない。また、本発明の保温材は液相で低粘性であるため、熱間でタンディッシュを繰り返し使用する場合にも、保温材の排滓性が非常に向上するといった利点もある。 When the heat insulating material of the present invention is added onto the surface of the molten steel in the tundish and the continuous casting of the steel is performed, contamination of the molten steel due to air oxidation and the reaction between the heat insulating material and the molten steel can be reliably prevented, and then No tundish refractory melts. In addition, since the heat insulating material of the present invention is low-viscosity in the liquid phase, there is an advantage that the heat-removing material can be greatly improved even when the tundish is repeatedly used in the hot state.
さらに、本発明の保温材をタンディッシュ内に添加して、予め真空脱ガス装置内でＴｉ脱酸された溶鋼を鋳造すると、保温材中Ｔｉの溶解および、保温材中ＴｉＯ2と溶鋼中Ｔｉとの反応は何れも起こり難いため、本発明の保温材はＴｉ脱酸溶鋼の鋳造に最適な組成となっている。 Furthermore, when the heat insulating material of the present invention is added to the tundish and the molten steel deoxidized in advance in a vacuum degassing apparatus is cast, melting of Ti in the heat insulating material and TiO 2 in the heat insulating material and Ti in the molten steel Therefore, the heat insulating material of the present invention has an optimal composition for casting of Ti deoxidized molten steel.
以下に、実施例及び比較例を挙げて、本発明について説明する。 Hereinafter, the present invention will be described with reference to examples and comparative examples.
（実施例１）
３質量％ＳｉＯ2、４２質量％ＣａＯ、３０質量％Ａｌ2Ｏ3、２０質量％ＭｇＯ、５質量％Ｔｉの保温材４００ｋｇを容量６０ｔのタンディッシュに添加し、炭素濃度０．０４質量％の低炭アルミキルド溶鋼を４００分間鋳造した。なお、タンディッシュ内の溶鋼温度は１５５８℃である。鋳造寸法は、厚み２４５ｍｍ×幅１５００ｍｍで、８５００ｍｍ長さに切断して１コイル単位とした。このスラブを常法により熱間圧延、冷間圧延し、最終的に厚み０．７ｍｍ×幅１５００ｍｍコイルの冷延鋼板とした。
Example 1
400 kg of a heat insulating material of 3% by mass SiO 2 , 42% by mass CaO, 30% by mass Al 2 O 3 , 20% by mass MgO, 5% by mass Ti is added to a tundish with a capacity of 60 t, and the carbon concentration is 0.04% by mass. Low-carbon aluminum killed molten steel was cast for 400 minutes. In addition, the molten steel temperature in a tundish is 1558 degreeC. Casting dimensions were 245 mm thickness x 1500 mm width, and were cut into 8500 mm lengths to make one coil unit. This slab was hot-rolled and cold-rolled by a conventional method to finally form a cold-rolled steel sheet having a thickness of 0.7 mm × width of 1500 mm coil.
保温材の空気酸化防止効果、溶鋼との反応防止効果および耐火物溶損防止効果は、定常鋳造領域でタンディッシュ入側と出側の溶鋼をサンプリングし、ガス分析を行うことにより測定したタンディッシュ入側と出側の溶鋼中の全酸素濃度の上昇量、及び冷延鋼板の１コイル当たりに発生した表面欠陥の目視観察による発生個数により評価した。 The antioxidation effect of the thermal insulation material, the reaction prevention effect with molten steel, and the refractory refractory prevention effect were measured by sampling the molten steel on the inlet and outlet sides of the tundish in the steady casting region and performing gas analysis. The evaluation was made based on the amount of increase in the total oxygen concentration in the molten steel on the entry side and the exit side, and the number of surface defects generated per one coil of the cold-rolled steel sheet by visual observation.
本発明の保温材により空気酸化、保温材による溶鋼酸化およびタンディッシュ耐火物溶損による溶鋼汚染が防止された結果、タンディッシュ入側と出側の全酸素濃度は０．００３７質量％と０．００３０質量％で全酸素濃度の上昇はなかった。また、表面欠陥の発生もなかった。 As a result of prevention of air oxidation, molten steel oxidation by the heat insulating material, and molten steel contamination by tundish refractory erosion damage by the heat insulating material of the present invention, the total oxygen concentration on the tundish inlet side and outlet side is 0.0037% by mass. There was no increase in the total oxygen concentration at 0030 mass%. Further, no surface defects were generated.
（実施例２）
２質量％ＳｉＯ2、４０質量％ＣａＯ、２１質量％Ａｌ2Ｏ3、１２質量％ＭｇＯ、２０質量％ＴｉＯ2、５質量％Ｔｉ保温材４００ｋｇを容量６０ｔのタンディッシュに添加し、炭素濃度０．００３質量％の極低炭Ｔｉ脱酸溶鋼を４００分間鋳造した。なお、タンディッシュ内の溶鋼温度は１５６０℃である。鋳造寸法は、厚み２４５ｍｍ×幅１５００ｍｍで、８５００ｍｍ長さに切断して１コイル単位とした。このスラブを常法により熱間圧延、冷間圧延し、最終的に厚み０．７ｍｍ×幅１５００ｍｍコイルの冷延鋼板とした。
(Example 2)
400 kg of 2% by mass SiO 2 , 40% by mass CaO, 21% by mass Al 2 O 3 , 12% by mass MgO, 20% by mass TiO 2 , 5% by mass Ti heat insulating material was added to a tundish with a capacity of 60 t, and the carbon concentration was 0 0.003 mass% ultra-low carbon Ti deoxidized molten steel was cast for 400 minutes. In addition, the molten steel temperature in a tundish is 1560 degreeC. Casting dimensions were 245 mm thickness x 1500 mm width, and were cut into 8500 mm lengths to make one coil unit. This slab was hot-rolled and cold-rolled by a conventional method to finally obtain a cold-rolled steel sheet having a thickness of 0.7 mm and a width of 1500 mm.
本発明の保温材により空気酸化と保温材による溶鋼汚染が防止され、且つ耐火物の溶損も抑制された結果、タンディッシュ入側と出側の溶鋼中の全酸素濃度は０．００４０質量％と０．００３２質量％で全酸素濃度の上昇はなかった。また、表面欠陥の発生もなかった。 As a result of preventing the oxidation of the molten steel by air oxidation and the heat insulating material by the heat insulating material of the present invention and suppressing the refractory erosion, the total oxygen concentration in the molten steel on the entry side and the outlet side of the tundish is 0.0040% by mass. There was no increase in the total oxygen concentration at 0.0032 mass%. Further, no surface defects were generated.
（比較例１）
１００質量％ＭｇＯの保温材４００ｋｇを容量６０ｔのタンディッシュに添加し、炭素濃度０．０４質量％の低炭アルミキルド鋼を４００分間鋳造した。鋳造寸法は、厚み２４５ｍｍ×幅１５００ｍｍで、８５００ｍｍ長さに切断して１コイル単位とした。このスラブを常法により熱間圧延、冷間圧延し、最終的に厚み０．７ｍｍ×幅１５００ｍｍコイルの冷延鋼板とした。
(Comparative Example 1)
400 kg of a heat retention material of 100% by mass MgO was added to a tundish having a capacity of 60 t, and low carbon aluminum killed steel having a carbon concentration of 0.04% by mass was cast for 400 minutes. Casting dimensions were 245 mm thickness x 1500 mm width, and were cut into 8500 mm lengths to make one coil unit. This slab was hot-rolled and cold-rolled by a conventional method to finally obtain a cold-rolled steel sheet having a thickness of 0.7 mm and a width of 1500 mm.
ＭｇＯ系の従来保温材を使用したため、保温材層を通して酸素が侵入し、溶鋼の再酸化が生じた結果、タンディッシュ入側から出側にかけて溶鋼中の全酸素濃度が０．００３６質量％から０．００６０質量％まで上昇した。また、表面欠陥も平均で６個／コイル発生した。 Since MgO-based conventional heat insulating material is used, oxygen enters through the heat insulating material layer and reoxidation of the molten steel occurs. As a result, the total oxygen concentration in the molten steel from 0.0036% by mass to 0% from the tundish inlet side to the outlet side. It increased to 0060% by mass. In addition, the average number of surface defects was 6 / coil.
（比較例２）
２０質量％ＳｉＯ2、８０質量％ＭｇＯの保温材４００ｋｇを容量６０ｔのタンディッシュに添加し、炭素濃度０．００２８質量％の極低炭アルミキルド鋼を４００分間鋳造した。鋳造寸法は、厚み２４５ｍｍ×幅１５００ｍｍで、８５００ｍｍ長さに切断して１コイル単位とした。このスラブを常法により熱間圧延、冷間圧延し、最終的に厚み０．７ｍｍ×幅１５００ｍｍコイルの冷延鋼板とした。
(Comparative Example 2)
400 kg of a heat insulating material of 20% by mass SiO 2 and 80% by mass MgO was added to a tundish having a capacity of 60 t, and an ultra low carbon aluminum killed steel having a carbon concentration of 0.0028% by mass was cast for 400 minutes. Casting dimensions were 245 mm thickness x 1500 mm width, and were cut into 8500 mm lengths to make one coil unit. This slab was hot-rolled and cold-rolled by a conventional method to finally obtain a cold-rolled steel sheet having a thickness of 0.7 mm and a width of 1500 mm.
ＳｉＯ2を含有するＭｇＯ系の従来保温材を使用したため、空気による溶鋼の再酸化と、保温材中ＳｉＯ2と溶鋼との反応により溶鋼汚染が生じた結果、タンディッシュ入側から出側にかけて溶鋼中の全酸素濃度が０．００３質量％から０．００５９質量％まで上昇した。また、表面欠陥も平均で８個／コイル発生した。 Because MgO-based conventional heat insulating material containing SiO 2 was used, molten steel was contaminated by reoxidation of molten steel by air and reaction between SiO 2 and molten steel in the heat insulating material, resulting in molten steel from the tundish inlet side to the outlet side. The total oxygen concentration inside increased from 0.003 mass% to 0.0059 mass%. In addition, an average of 8 surface defects / coil was generated.
（比較例３）
１６質量％ＳｉＯ2、５８質量％ＣａＯ、２６質量％Ａｌ2Ｏ3の保温材４００ｋｇを容量６０ｔのタンディッシュに添加し、炭素濃度０．００２８質量％の極低炭アルミキルド鋼を４００分間鋳造した。鋳造寸法は、厚み２４５ｍｍ×幅１５００ｍｍで、８５００ｍｍ長さに切断して１コイル単位とした。このスラブを常法により熱間圧延、冷間圧延し、最終的に厚み０．７ｍｍ×幅１５００ｍｍコイルの冷延鋼板とした。
(Comparative Example 3)
400 kg of a heat insulating material of 16% by mass SiO 2 , 58% by mass CaO, 26% by mass Al 2 O 3 was added to a tundish having a capacity of 60 t, and a very low carbon aluminum killed steel having a carbon concentration of 0.0028% by mass was cast for 400 minutes. . Casting dimensions were 245 mm thickness x 1500 mm width, and were cut into 8500 mm lengths to make one coil unit. This slab was hot-rolled and cold-rolled by a conventional method to finally obtain a cold-rolled steel sheet having a thickness of 0.7 mm and a width of 1500 mm.
ＳｉＯ2を含有する高ＣａＯ−低Ａｌ2Ｏ3系の保温材を使用したため、空気による溶鋼の再酸化と、保温材中ＳｉＯ2と溶鋼との反応により溶鋼汚染が生じた結果、タンディッシュ入側から出側にかけて溶鋼中の全酸素濃度が０．００３２質量％から０．００６２質量％まで上昇した。また、表面欠陥も平均で８．２個／コイル発生した。
Since a high CaO-low Al 2 O 3 type heat insulating material containing SiO 2 was used, molten steel was contaminated by reoxidation of the molten steel by air and reaction between SiO 2 and the molten steel in the heat insulating material. The total oxygen concentration in the molten steel increased from 0.0032 mass% to 0.0062 mass% from the side to the outlet side. In addition, an average of 8.2 surface defects / coil was generated.
Claims (6)
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP2005304210A JP2007111721A (en) | 2005-10-19 | 2005-10-19 | Heat-retaining material for molten steel surface, and continuous casting method for steel using the same |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP2005304210A JP2007111721A (en) | 2005-10-19 | 2005-10-19 | Heat-retaining material for molten steel surface, and continuous casting method for steel using the same |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| JP2007111721A true JP2007111721A (en) | 2007-05-10 |
Family
ID=38094372
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| JP2005304210A Withdrawn JP2007111721A (en) | 2005-10-19 | 2005-10-19 | Heat-retaining material for molten steel surface, and continuous casting method for steel using the same |
Country Status (1)
| Country | Link |
|---|---|
| JP (1) | JP2007111721A (en) |
Cited By (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JP2009197285A (en) * | 2008-02-22 | 2009-09-03 | Nippon Steel Corp | Method for producing high clean steel slab |
| JP2019000903A (en) * | 2017-06-12 | 2019-01-10 | Ｊｆｅスチール株式会社 | Smelting method and continuous casting method of steel |
| CN110666112A (en) * | 2019-09-25 | 2020-01-10 | 安徽省含山县华平铸造厂（普通合伙） | Heat-insulating covering agent for molten iron |
-
2005
- 2005-10-19 JP JP2005304210A patent/JP2007111721A/en not_active Withdrawn
Cited By (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JP2009197285A (en) * | 2008-02-22 | 2009-09-03 | Nippon Steel Corp | Method for producing high clean steel slab |
| JP2019000903A (en) * | 2017-06-12 | 2019-01-10 | Ｊｆｅスチール株式会社 | Smelting method and continuous casting method of steel |
| CN110666112A (en) * | 2019-09-25 | 2020-01-10 | 安徽省含山县华平铸造厂（普通合伙） | Heat-insulating covering agent for molten iron |
Similar Documents
| Publication | Publication Date | Title |
|---|---|---|
| CN104858382B (en) | A kind of tundish covering flux and its application | |
| JP4855554B2 (en) | Molten steel surface thermal insulation and molten steel surface thermal insulation method | |
| JP2007290002A (en) | Heat insulating material for molten steel surface and method for continuously casting steel using the same | |
| JP2007111721A (en) | Heat-retaining material for molten steel surface, and continuous casting method for steel using the same | |
| JP2007290003A (en) | Heat insulating material for molten steel surface and method for continuously casting steel using the same | |
| JP4786252B2 (en) | Molten steel insulation | |
| KR20130009472A (en) | Mold powder for continuous casting | |
| JP4855552B2 (en) | Molten steel surface insulation method | |
| JP2006175472A (en) | Mold powder for continuous casting of steel, and continuous casting method of steel | |
| JP2007111720A (en) | Heat-retaining material for molten steel surface, and continuous casting method for steel using the same | |
| RU2380194C2 (en) | Heat insulation slag-generating mixture | |
| JP3081067B2 (en) | Liquid steel surface heat insulator | |
| JP4486526B2 (en) | Molten steel surface heat insulating material and continuous casting method of steel using the same | |
| CN112760456A (en) | Bismuth-containing oriented silicon steel smelting method enabling bismuth yield to be not less than 70% | |
| JP3103465B2 (en) | Liquid steel surface heat insulator | |
| JP4441425B2 (en) | Steel continuous casting method | |
| JP2991879B2 (en) | Liquid steel surface heat insulator | |
| JPH06179059A (en) | Surface insulating material for molten steel | |
| JP4750985B2 (en) | Molten steel surface heat insulating material and continuous casting method of steel using the same | |
| JP3718410B2 (en) | Manufacturing method of high clean aluminum killed steel | |
| JPH05337617A (en) | Insulating material for molten steel surface | |
| JPH07124741A (en) | Surface heat insulating material for molten steel | |
| JP2009214139A (en) | Heat retention method in tundish for holding cleanliness of molten steel | |
| JPH05293616A (en) | Insulating material for molten steel surface | |
| JPH06170508A (en) | Surface insulating material for molten steel |
Legal Events
| Date | Code | Title | Description |
|---|---|---|---|
| A300 | Withdrawal of application because of no request for examination |
Free format text: JAPANESE INTERMEDIATE CODE: A300 Effective date: 20090106 |