JP2007054861A - Tundish for continuous casting and method for producing cast slab - Google Patents
Tundish for continuous casting and method for producing cast slab Download PDFInfo
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- JP2007054861A JP2007054861A JP2005242542A JP2005242542A JP2007054861A JP 2007054861 A JP2007054861 A JP 2007054861A JP 2005242542 A JP2005242542 A JP 2005242542A JP 2005242542 A JP2005242542 A JP 2005242542A JP 2007054861 A JP2007054861 A JP 2007054861A
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- 238000009749 continuous casting Methods 0.000 title claims abstract description 22
- 238000004519 manufacturing process Methods 0.000 title claims description 8
- 229910000831 Steel Inorganic materials 0.000 claims abstract description 173
- 239000010959 steel Substances 0.000 claims abstract description 173
- 238000005266 casting Methods 0.000 claims description 9
- 230000008439 repair process Effects 0.000 abstract description 5
- 230000002542 deteriorative effect Effects 0.000 abstract 1
- 238000002347 injection Methods 0.000 description 37
- 239000007924 injection Substances 0.000 description 37
- 239000002184 metal Substances 0.000 description 13
- 229910052751 metal Inorganic materials 0.000 description 13
- 238000004458 analytical method Methods 0.000 description 9
- 238000007667 floating Methods 0.000 description 9
- XEEYBQQBJWHFJM-UHFFFAOYSA-N Iron Chemical compound [Fe] XEEYBQQBJWHFJM-UHFFFAOYSA-N 0.000 description 8
- 230000007423 decrease Effects 0.000 description 8
- 239000002893 slag Substances 0.000 description 8
- 230000003749 cleanliness Effects 0.000 description 5
- 230000000694 effects Effects 0.000 description 5
- 238000000034 method Methods 0.000 description 5
- XLYOFNOQVPJJNP-UHFFFAOYSA-N water Substances O XLYOFNOQVPJJNP-UHFFFAOYSA-N 0.000 description 5
- 229910052742 iron Inorganic materials 0.000 description 4
- 230000008569 process Effects 0.000 description 4
- 238000007654 immersion Methods 0.000 description 3
- 230000009467 reduction Effects 0.000 description 3
- 238000000926 separation method Methods 0.000 description 3
- 230000002411 adverse Effects 0.000 description 2
- 238000005516 engineering process Methods 0.000 description 2
- 239000000463 material Substances 0.000 description 2
- OKTJSMMVPCPJKN-UHFFFAOYSA-N Carbon Chemical compound [C] OKTJSMMVPCPJKN-UHFFFAOYSA-N 0.000 description 1
- 229910000655 Killed steel Inorganic materials 0.000 description 1
- PNEYBMLMFCGWSK-UHFFFAOYSA-N aluminium oxide Inorganic materials [O-2].[O-2].[O-2].[Al+3].[Al+3] PNEYBMLMFCGWSK-UHFFFAOYSA-N 0.000 description 1
- 230000000903 blocking effect Effects 0.000 description 1
- 229910052799 carbon Inorganic materials 0.000 description 1
- 238000004140 cleaning Methods 0.000 description 1
- 238000005097 cold rolling Methods 0.000 description 1
- 230000000052 comparative effect Effects 0.000 description 1
- 230000001276 controlling effect Effects 0.000 description 1
- 238000005206 flow analysis Methods 0.000 description 1
- 238000005098 hot rolling Methods 0.000 description 1
- 230000006872 improvement Effects 0.000 description 1
- 238000011065 in-situ storage Methods 0.000 description 1
- 238000007689 inspection Methods 0.000 description 1
- 238000009434 installation Methods 0.000 description 1
- 238000005339 levitation Methods 0.000 description 1
- 238000012986 modification Methods 0.000 description 1
- 230000004048 modification Effects 0.000 description 1
- 239000002245 particle Substances 0.000 description 1
- 230000001105 regulatory effect Effects 0.000 description 1
- 238000004904 shortening Methods 0.000 description 1
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- Continuous Casting (AREA)
Abstract
Description
本発明は、連続鋳造工程において取鍋から注入された溶鋼を鋳型に中継供給するためのタンディッシュ、並びに、このタンディッシュを使用した鋳片の製造方法に関し、詳しくは、タンディッシュ内に注入された溶鋼中の酸化物系非金属介在物を効率良く浮上分離することのできるタンディッシュ、並びに、このタンディッシュを使用した鋳片の製造方法に関するものである。 The present invention relates to a tundish for relay-feeding molten steel injected from a ladle in a continuous casting process to a mold, and a method for producing a slab using the tundish, and more specifically, injected into the tundish. The present invention relates to a tundish capable of efficiently levitating and separating oxide-based nonmetallic inclusions in molten steel, and a slab manufacturing method using the tundish.
鋼の連続鋳造においては、取鍋内の溶鋼を一旦タンディッシュに注入し、タンディッシュ内に所定量の溶鋼が滞在した状態で、タンディッシュ内の溶鋼を鋳型に注入している。取鍋内の溶鋼がなくなった場合には、空の取鍋を別のヒートの溶鋼が収容された取鍋と交換して連続連続鋳造（以下、「連々鋳」と記す）が行われている。 In continuous casting of steel, the molten steel in the ladle is once poured into the tundish, and the molten steel in the tundish is poured into the mold with a predetermined amount of molten steel staying in the tundish. When the molten steel in the ladle runs out, continuous empty casting (hereinafter referred to as “continuous casting”) is performed by replacing the empty ladle with a ladle containing molten steel of another heat. .
この連続鋳造工程においては、取鍋交換時の非定常部鋳片の品質が定常鋳造域の鋳片に比べて低下するという問題がある。これは、取鍋交換時、取鍋内に収容される溶鋼が少なくなった時点で、取鍋内の溶鋼上に存在するスラグが溶鋼とともにタンディッシュ内に流出し、更にタンディッシュから鋳型内に注入されて鋳片に捕捉されるからである。取鍋交換時には、タンディッシュ内に滞在する溶鋼量も減少し、タンディッシュ内における溶鋼の滞在時間が短くなって、酸化物系非金属介在物（以下、「介在物」と記す）の浮上分離に悪影響を与えることも品質の低下を招く原因になっている。更に、取鍋交換時には、取鍋内及びタンディッシュ内の溶鋼量が減少することにより溶鋼温度が低下し、溶鋼中に懸濁したスラグの溶鋼からの浮上分離が悪くなることも品質の低下を招く原因になっている。このように、タンディッシュを用いた連続鋳造工程においては、取鍋交換時の溶鋼は品質に悪影響を及ぼし易い条件下にある。 In this continuous casting process, there is a problem in that the quality of the unsteady portion slab when the ladle is replaced is lower than that of the slab in the steady casting region. This is because when the molten steel contained in the ladle is reduced when the ladle is replaced, the slag present on the molten steel in the ladle flows out into the tundish together with the molten steel, and further enters the mold from the tundish. This is because it is injected and captured by the slab. When changing the ladle, the amount of molten steel staying in the tundish also decreases, and the staying time of the molten steel in the tundish is shortened, so that floating separation of oxide-based non-metallic inclusions (hereinafter referred to as “inclusions”) occurs. Adversely affecting the quality of the product can also cause a decline in quality. Furthermore, when the ladle is replaced, the molten steel temperature decreases due to a decrease in the amount of molten steel in the ladle and in the tundish, and the levitation and separation of the slag suspended in the molten steel from the molten steel also deteriorates the quality. It is a cause. Thus, in the continuous casting process using a tundish, the molten steel at the time of ladle replacement is in a condition that tends to adversely affect the quality.
一方、タンディッシュに関して連続鋳造の操業上からは、耐火物コストの削減、堰の撤廃による補修時間の短縮及び簡略化、更には、タンディッシュ内残溶鋼の削減による鋳片歩留まりの向上などの要求がある。これらの要求の多くは、前述した鋳片品質対策とは二律背反の関係であり、従って、構造が簡便でありながら品質向上に効果的なタンディッシュ形状が強く望まれてきた。 On the other hand, for continuous tundish operation, demands for reducing refractory costs, shortening and simplifying repair time by eliminating weirs, and improving slab yield by reducing residual molten steel in tundish. There is. Many of these requirements are in contradiction to the slab quality measures described above, and therefore, a tundish shape that is effective in improving quality while having a simple structure has been strongly desired.
この目的のために、分離可能な堰を設置したタンディッシュが特許文献１に提案されている。即ち、タンディッシュ内に分離可能な堰を設け、補修時には堰を取り除き、鋳造中にはタンディッシュ内の溶鋼湯面の高さに応じて堰の設置高さを変更するという技術である。特許文献１によれば、このタンディッシュを使用することにより、鋳片の品質を確保することができると同時に、補修作業の簡略化及び鋳片歩留まりの向上が達成されるとしている。しかしながら、この技術では堰を動かすための装置が新たに必要であり、しかも、溶鋼に浸漬させた状態で堰を移動させる必要があり、堰が割れるなどのリスクを伴い、実機での使用は困難といわざるを得ない。 For this purpose, Patent Document 1 proposes a tundish provided with a separable weir. That is, a separable weir is provided in the tundish, the weir is removed during repair, and the height of the weir is changed according to the height of the molten steel surface in the tundish during casting. According to Patent Document 1, by using this tundish, the quality of the slab can be ensured, and at the same time, the repair work can be simplified and the slab yield can be improved. However, this technology requires a new device for moving the weir, and it is necessary to move the weir while it is immersed in molten steel, which involves the risk of breaking the weir and is difficult to use in actual equipment. I have to say.
ところで、従来のタンディッシュ形状と品質に関する文献には、非特許文献１などがある。ここでは、おおよそ１７〜７６トンの溶鋼重量でスロープのないタンディッシュの定常解析を実施し、最適な深さと幅の関係について議論している。
以上説明したように、鋼の連続鋳造工程においては、構造が簡便でありながら品質向上に効果的なタンディッシュが切望されているにも拘わらず、未だ有効な提案はなされていないのが現状である。 As described above, in the continuous casting process of steel, although there is a keen desire for a tundish that is simple in structure and effective in improving quality, no effective proposal has yet been made. is there.
本発明は上記事情に鑑みてなされたもので、その目的とするところは、タンディッシュ寸法（重量）は１０〜８０トン、最大深さが０．７〜２．０ｍのタンディッシュを対象とし、タンディッシュ底にスロープや堰を設置することにより、取鍋交換のような品質の悪化し易い条件においても、溶鋼中の介在物を効率的に浮上分離することのできる、低コストで且つ補修が容易な連続鋳造用タンディッシュを提供することであり、また、このタンディッシュを使用した鋳片の製造方法を提供することである。 The present invention has been made in view of the above circumstances. The object of the present invention is for a tundish having a tundish size (weight) of 10 to 80 tons and a maximum depth of 0.7 to 2.0 m. By installing slopes and weirs at the bottom of the tundish, the inclusions in the molten steel can be efficiently levitated and separated even under conditions where quality is likely to deteriorate, such as ladle replacement. It is to provide an easy tundish for continuous casting, and to provide a method for producing a slab using the tundish.
上記課題を解決するための第１の発明に係る連続鋳造用タンディッシュは、取鍋から注入された溶鋼を、溶鋼流出孔を通して鋳型に中継供給する連続鋳造用タンディッシュであって、タンディッシュ内における溶鋼の最も深い位置が溶鋼流出孔の部位であり、最も浅い位置が取鍋からの注入点の部位であり、収容能力最大の溶鋼を滞在させた際に最も深い位置と最も浅い位置との深さの差が、最も深い位置の深さに０．１５〜０．３０を乗算した範囲であり、且つ、取鍋からの注入点の部位を含む底面の水平部の端部には、タンディッシュ底部を閉鎖する５０〜３５０ｍｍ高さの堰が設置されていることを特徴とするものである。 The tundish for continuous casting according to the first invention for solving the above-mentioned problem is a tundish for continuous casting that feeds molten steel injected from a ladle to a mold through a molten steel outflow hole. The deepest position of the molten steel is the site of the molten steel outflow hole, the shallowest position is the site of the pouring point from the ladle, and the deepest position and the shallowest position when the molten steel with the maximum capacity is stayed. The difference in depth is a range obtained by multiplying the depth of the deepest position by 0.15 to 0.30, and at the end of the horizontal portion of the bottom surface including the pouring point from the ladle, A dam with a height of 50 to 350 mm for closing the bottom of the dish is installed.
第２の発明に係る鋳片の製造方法は、第１の発明に記載の連続鋳造用タンディッシュに、取鍋に収容された溶鋼を注入し、次いで前記タンディッシュに注入された溶鋼を鋳型に注入して鋳造することを特徴とするものである。 According to a second aspect of the present invention, there is provided a method for producing a slab, wherein molten steel contained in a ladle is poured into the continuous casting tundish according to the first aspect, and then the molten steel poured into the tundish is used as a mold. It is characterized by being cast by casting.
本発明に係る連続鋳造用タンディッシュにおいては、取鍋からの注入点の部位と鋳型への溶鋼流出孔の部位との深さの差を適切に設定し、且つ、最も浅い部位である注入点を含む水平部分の端部には上昇流を生じさせる堰を設置しているので、比較的簡単な構造のタンディッシュであるにも拘わらず、タンディッシュ内における介在物の浮上分離に優れ、溶鋼の清浄性が格段に向上し、取鍋交換時のような品質の劣化し易い条件下であっても介在物の少ない鋳片を安定して得ることができる。また、比較的簡単な構造であるので、タンディッシュの補修作業を妨げることがない。 In the tundish for continuous casting according to the present invention, the difference in depth between the site of the injection point from the ladle and the site of the molten steel outflow hole to the mold is set appropriately, and the injection point is the shallowest site Since weirs that generate upward flow are installed at the end of the horizontal part including the steel, it is excellent in the floating separation of inclusions in the tundish despite the relatively simple structure of the tundish. As a result, the slab with less inclusions can be obtained stably even under conditions where the quality is likely to deteriorate, such as when changing the ladle. Further, since the structure is relatively simple, the tundish repair work is not hindered.
以下、本発明を具体的に説明する。先ず、本発明に至った検討結果について説明する。 The present invention will be specifically described below. First, the examination results that led to the present invention will be described.
本発明者等は、タンディッシュの入口即ち取鍋からの溶鋼の注入点における溶鋼深さ、並びに、タンディッシュの出口即ち鋳型への溶鋼流出孔における溶鋼深さが、介在物の浮上性に及ぼす影響について、流動解析モデルを用いて検討した。解析対象のタンディッシュは、中央部に取鍋からの注入点があり、注入された溶鋼が左右の溶鋼流出孔に向かう型式の、２ストランドの直方体状のタンディッシュであり、幅が１．２ｍ、注入点から両方の溶鋼流出孔との距離がそれぞれ４ｍである。タンディッシュへの溶鋼の注入流量をストランド当たり５トン／分とし、溶鋼の温度を１５５０℃、そのときの密度を７ｇ／ｃｍ3 とした。主要な解析条件を表１に示す。 The inventors have found that the molten steel depth at the injection point of the molten steel from the tundish inlet or ladle and the molten steel depth at the outlet of the tundish or molten steel outlet to the mold affect the floatability of inclusions. The impact was examined using a flow analysis model. The tundish to be analyzed is a two-strand rectangular tundish with a pouring point from the ladle in the center, and the injected molten steel is directed to the left and right molten steel outflow holes. The distance from the injection point to both molten steel outflow holes is 4 m. The flow rate of molten steel into the tundish was 5 tons / min per strand, the temperature of the molten steel was 1550 ° C., and the density at that time was 7 g / cm 3 . Table 1 shows the main analysis conditions.
先ず、タンディッシュの入口（注入点）からタンディッシュ内に入った介在物のタンディッシュ内における浮上性について検討した。解析に当たり、タンディッシュの深さは長手方向の位置に拘わらず一定とし、介在物の粒径を５０μｍとし、介在物は溶鋼とともに入口（注入点）から供給され、タンディッシュ内の溶鋼湯面に達した介在物はその場で捕捉され、つまり溶鋼と分離され、捕捉されなかった介在物が溶鋼流出孔から鋳型内に注入されるとした。介在物の流出率を、供給された介在物のうちで捕捉されずに鋳型に流出したものの割合（百分率で表示）として調査した。 First, the floating property in the tundish of inclusions that entered the tundish from the inlet (injection point) of the tundish was examined. In the analysis, the tundish depth is constant regardless of the position in the longitudinal direction, the inclusion particle size is 50 μm, the inclusions are supplied from the inlet (injection point) together with the molten steel, and the molten steel surface on the molten steel surface in the tundish The reached inclusions were captured in situ, that is, separated from the molten steel, and inclusions that were not captured were injected into the mold from the molten steel outflow hole. Inclusion outflow rate was investigated as the percentage of the inclusions supplied that were not trapped and flowed into the mold (expressed as a percentage).
図１に、タンディッシュ深さと介在物の流出率との関係の解析結果を示す。図１に示すように、タンディッシュの深さが０．４ｍと浅い場合には、介在物の流出率は２０％であるが、タンディッシュの深さが深くなるにつれて流出率が増加することが明らかになった。また、タンディッシュ内の溶鋼の流れを見ると、溶鋼深さが浅い場合には、図２に浅いタンディッシュにおける溶鋼の流れを示すように、比較的早くタンディッシュの底面に溶鋼が達し、反転流による上昇流が入口（注入点）の近くで生じていて、多くの介在物が入口（注入点）の近傍で湯面上に分離することが明らかになった。一方、深さの深いタンディッシュでは、図３に深いタンディッシュにおける溶鋼の流れを示すように、反転流は存在するものの、入口（注入点）から離れた場所で生じており、湯面に捕捉される介在物は少ないことが明らかになった。尚、図２及び図３における符号１はタンディッシュ、２は溶鋼流出孔、３は注入点、５はロングノズルであり、図２及び図３ではタンディッシュの片側半分のみを示している。 In FIG. 1, the analysis result of the relationship between the tundish depth and the outflow rate of inclusions is shown. As shown in FIG. 1, when the depth of the tundish is as shallow as 0.4 m, the outflow rate of inclusions is 20%, but the outflow rate may increase as the tundish depth becomes deeper. It was revealed. Also, looking at the flow of molten steel in the tundish, when the molten steel depth is shallow, the molten steel reaches the bottom surface of the tundish relatively quickly, as shown in Fig. 2 showing the flow of molten steel in the shallow tundish. It was revealed that the upward flow caused by the flow occurred near the inlet (injection point), and many inclusions separated on the molten metal surface near the inlet (injection point). On the other hand, in the deep tundish, as shown in Fig. 3, the flow of molten steel in the deep tundish, although there is a reversal flow, it occurs at a location away from the inlet (injection point) and is trapped on the molten metal surface. It became clear that there were few inclusions. 2 and 3, reference numeral 1 is a tundish, 2 is a molten steel outflow hole, 3 is an injection point, 5 is a long nozzle, and FIGS. 2 and 3 show only one half of the tundish.
これらの解析結果から、入口（注入点）から供給された介在物をタンディッシュ内で効率的に浮上分離させるためには、入口（注入点）近傍の溶鋼深さを浅く保つことが有効であることが分かった。 From these analysis results, it is effective to keep the molten steel depth near the inlet (injection point) shallow in order to efficiently float and separate inclusions supplied from the inlet (injection point) in the tundish. I understood that.
次に、タンディッシュ内の湯面に浮上した介在物の巻き込みについて検討した。予め介在物をタンディッシュ内の湯面に浮遊させた状態で、入口（注入点）からストランド当たり５トン／分の溶鋼を供給し、湯面に浮遊させた介在物が溶鋼流に巻き込まれて溶鋼流出孔から鋳型に流出する介在物の割合（百分率で表示）を介在物の巻き込み率として調査した。ここで、一旦溶鋼中に巻き込まれてもタンディッシュ内湯面に浮上した介在物は、その場で湯面に捕捉され、二度と溶鋼中には巻き込まれないと仮定した。タンディッシュの深さは長手方向の位置に拘わらず一定とした。 Next, the inclusion of inclusions floating on the surface of the hot water in the tundish was examined. With the inclusions suspended in advance on the molten metal surface in the tundish, 5 tons / min of molten steel per strand is supplied from the inlet (injection point), and the inclusions suspended on the molten metal surface are entrained in the molten steel flow. The ratio of inclusions flowing out from the molten steel outflow hole into the mold (expressed as a percentage) was investigated as the inclusion inclusion rate. Here, it was assumed that the inclusions floating on the inner surface of the tundish once caught in the molten steel were captured by the molten metal on the spot and never caught in the molten steel. The tundish depth was constant regardless of the position in the longitudinal direction.
図４に、タンディッシュ深さと介在物の巻き込み率との関係の解析結果を示す。図４に示すように、タンディッシュ深さが０．４ｍの場合には介在物の巻き込み率が２０％程度であるが、タンディッシュ深さが深くなると巻き込み率が低下することが判明した。 FIG. 4 shows an analysis result of the relationship between the tundish depth and the inclusion inclusion rate. As shown in FIG. 4, when the tundish depth is 0.4 m, the inclusion rate is about 20%, but it has been found that the inclusion rate decreases as the tundish depth increases.
図５に、浅いタンディッシュにおける湯面に浮遊する介在物の飛跡を、また、図６に、深いタンディッシュにおける湯面に浮遊する介在物の飛跡を示す。タンディッシュ深さが浅い場合には、図５に示すように、溶鋼流出孔近傍における巻き込みが特に強く、多くの介在物が溶鋼流出孔に達することが分かった。一方、タンディッシュ深さが深い場合には、図６に示すような飛跡となり溶鋼流出孔の近傍で若干の巻き込みが見られるものの、溶鋼流出孔から離れた位置では一旦溶鋼中に巻き込まれても再び浮上することが明らかになった。尚、図５及び図６における符号１はタンディッシュ、２は溶鋼流出孔、３は注入点、５はロングノズルであり、図５及び図６ではタンディッシュの片側半分のみを示している。 FIG. 5 shows the tracks of inclusions floating on the molten metal surface in a shallow tundish, and FIG. 6 shows the tracks of inclusions floating on the molten metal surface in a deep tundish. When the tundish depth is shallow, as shown in FIG. 5, the entrainment in the vicinity of the molten steel outflow hole is particularly strong, and it has been found that many inclusions reach the molten steel outflow hole. On the other hand, when the tundish depth is deep, a track as shown in FIG. 6 is formed, and a slight entrainment is observed in the vicinity of the molten steel outflow hole, but even if the tundish is once caught in the molten steel at a position away from the molten steel outflow hole. It became clear that it surfaced again. 5 and 6, reference numeral 1 is a tundish, 2 is a molten steel outflow hole, 3 is an injection point, 5 is a long nozzle, and FIGS. 5 and 6 show only one half of the tundish.
これらの解析結果から、タンディッシュ内の湯面に浮遊している介在物の流出を防止するためには、タンディッシュ内の溶鋼深さを深く保つことが有効であることが分かった。 From these analysis results, it was found that maintaining the depth of the molten steel in the tundish is effective in preventing the outflow of inclusions floating on the molten metal surface in the tundish.
上記２つの解析結果をまとめることにより、以下の知見が得られた。即ち、タンディッシュ内に持ち込まれた介在物をタンディッシュ内で有効に浮上させ、一旦湯面に浮上した介在物が再び溶鋼中に巻き込まれないようにするためには、入口（注入点）の部位の深さを浅くし、逆に、出口（溶鋼流出孔）の部位の深さを深くすることが有効であるとの知見が得られた。この知見に基づき、入口部を浅くし、出口部を深くした形状のタンディッシュを製作し、タンディッシュ形状と鋳片の介在物との関係を調査した。 The following findings were obtained by combining the above two analysis results. That is, in order to effectively lift the inclusions brought into the tundish and prevent the inclusions once floated on the hot water surface from being caught again in the molten steel, It was found that it is effective to reduce the depth of the part and conversely to increase the depth of the part of the outlet (molten steel outflow hole). Based on this knowledge, a tundish with a shallow inlet and a deep outlet was manufactured, and the relationship between the tundish and the inclusions in the slab was investigated.
具体的には、図７に示す形状のタンディッシュを用い、幅を１．２ｍ、出口（溶鋼流出孔）の部位の深さを１．５ｍの一定とし、溶鋼の供給量を１分間当たり５トン、鋳型内の１／４幅位置の湯面における溶鋼流速を０．３ｍ／分となるように電磁力による制御を行いながら、入口（注入点）の部位の深さを種々変更した条件でスラブ鋳片を鋳造し、鋳造後、スラブ鋳片を熱間圧延し更に冷間圧延して得た薄鋼板において介在物個数を検査し、検出した介在物個数と、タンディッシュの注入点部位の溶鋼深さ（Ｄin）とタンディッシュの溶鋼流出孔部位の溶鋼深さ（Ｄout ）との溶鋼深さ比（Ｄin／Ｄout ）との関係を調査した。つまり、鋳片の清浄性と溶鋼深さ比（Ｄin／Ｄout ）との関係を調査した。ここで、図７は、試験に供したタンディッシュの内面形状（溶鋼のプロフィール）を示す斜視図であり、図中の符号１はタンディッシュ、２は溶鋼流出孔、３は注入点、５はロングノズルであり、タンディッシュの片側半分のみを示している。 Specifically, a tundish having the shape shown in FIG. 7 is used, the width is 1.2 m, the depth of the outlet (molten steel outflow hole) portion is constant at 1.5 m, and the supply amount of molten steel is 5 per minute. Under various conditions, the depth of the inlet (injection point) is varied while controlling the electromagnetic flow so that the molten steel flow velocity at the molten metal surface at the 1/4 width position in the mold is 0.3 m / min. Cast the slab slab, and after casting, inspect the number of inclusions in the thin steel plate obtained by hot rolling the slab slab and then cold rolling, and the number of inclusions detected and the tundish injection point site The relationship between the molten steel depth ratio (Din) and the molten steel depth ratio (Din / Dout) between the molten steel depth (Dout) at the molten steel outflow hole portion of the tundish was investigated. That is, the relationship between slab cleanability and molten steel depth ratio (Din / Dout) was investigated. Here, FIG. 7 is a perspective view showing the inner shape (profile of molten steel) of the tundish used for the test, in which 1 is the tundish, 2 is the molten steel outflow hole, 3 is the injection point, 5 is It is a long nozzle and shows only one half of the tundish.
図８に、溶鋼深さ比（Ｄin／Ｄout ）と介在物指数との関係の解析結果を示す。図８の縦軸に示す介在物指数は、注入点部位の溶鋼深さ（Ｄin）及び溶鋼流出孔部位の溶鋼深さ（Ｄout ）をともに１．５ｍとした場合の単位面積当たりの介在物個数を基準として無次元化した数値である。尚、取鍋交換時にはタンディッシュ内の溶鋼湯面位置が低下するために、取鍋交換時にも操業が可能なタンディッシュ形状としては、溶鋼深さ比（Ｄin／Ｄout ）が０．６以上の範囲である。 FIG. 8 shows the analysis result of the relationship between the molten steel depth ratio (Din / Dout) and the inclusion index. The inclusion index shown on the vertical axis in FIG. 8 is the number of inclusions per unit area when the molten steel depth (Din) at the injection point and the molten steel depth (Dout) at the molten steel outflow hole are both 1.5 m. It is a numerical value made dimensionless with reference to. Since the molten steel surface position in the tundish is lowered when the ladle is replaced, the molten steel depth ratio (Din / Dout) is 0.6 or more as a tundish shape that can be operated even when the ladle is replaced. It is a range.
図８に示すように、タンディッシュの深さを１．５ｍの一定とした場合に比較して溶鋼深さ比（Ｄin／Ｄout ）を０．７０〜０．８５とした場合には、溶鋼の清浄性に大幅な向上が見られることが分かった。つまり、溶鋼流出孔部位の溶鋼深さ（Ｄout ）と注入点部位の溶鋼深さ（Ｄin）との深さの差が、溶鋼流出孔部位の溶鋼深さ（Ｄout ）に０．１５〜０．３０を乗算した範囲の場合に、タンディッシュ内に持ち込まれた介在物はタンディッシュ内で効率良く浮上し、且つ、一旦湯面に浮上した介在物は再び溶鋼中に巻き込まれないようになることが分かった。溶鋼深さ比（Ｄin／Ｄout ）が０．７０未満になると、取鍋交換後の注入開始時に注入点におけるスプラッシュが激しくなり、それが巻き込まれることにより、安定した品質が得られない恐れがあり、好ましくない。 As shown in FIG. 8, when the depth ratio of the molten steel (Din / Dout) is 0.70 to 0.85 compared to the case where the depth of the tundish is fixed at 1.5 m, It was found that there was a significant improvement in cleanliness. That is, the difference in depth between the molten steel depth (Dout) at the molten steel outflow hole portion and the molten steel depth (Din) at the injection point portion is 0.15 to 0.005 in the molten steel depth (Dout) at the molten steel outflow hole portion. In the case of a range multiplied by 30, inclusions brought into the tundish will rise efficiently in the tundish, and inclusions once floated on the hot water surface will not be caught in the molten steel again. I understood. If the molten steel depth ratio (Din / Dout) is less than 0.70, the splash at the pouring point becomes intense at the start of pouring after replacing the ladle, and there is a risk that stable quality cannot be obtained due to entrainment. It is not preferable.
但し、上記対策のみでは品質厳格材には不十分であることが判明し、そこで、更なる介在物対策として、注入点近傍において効率的に介在物を浮上させるためにタンディッシュの底面に堰を設置することを検討した。鋳片の歩留まり、タンディッシュ補修の容易さ及び鋳片品質を考慮して、前述した図７に示すタンディッシュに堰を設置したタンディッシュ、つまり図９に示す形状のタンディッシュを使用して実機試験を実施した。使用した堰は高さが５０ｍｍで、タンディッシュ底部を全幅にわたって閉鎖する構造であり、この堰を、注入点を含む水平部の端部に設置した。タンディッシュの幅は１．２ｍ、出口（溶鋼流出孔）の部位の深さは１．５ｍの一定で、その他の操業条件は前記の通りである。ここで、図９は、試験に供したタンディッシュの内面形状（溶鋼のプロフィール）を示す斜視図であり、図中の符号１はタンディッシュ、２は溶鋼流出孔、３は注入点、４は堰、５はロングノズルであり、タンディッシュの片側半分のみを示している。 However, it has been found that the above measures alone are not sufficient for quality strict materials. Therefore, as a further inclusion countermeasure, a weir is placed on the bottom surface of the tundish in order to efficiently raise the inclusion in the vicinity of the injection point. Considered installation. Considering the yield of slabs, the ease of repairing the tundish and the quality of the slabs, the actual machine using the tundish with the weir installed in the tundish shown in FIG. 7, that is, the tundish having the shape shown in FIG. The test was conducted. The weir used had a height of 50 mm and had a structure in which the bottom of the tundish was closed over the entire width, and this weir was installed at the end of the horizontal part including the injection point. The width of the tundish is 1.2 m, the depth of the outlet (molten steel outflow hole) is constant at 1.5 m, and other operating conditions are as described above. Here, FIG. 9 is a perspective view showing the inner shape (profile of molten steel) of the tundish subjected to the test, in which 1 is the tundish, 2 is the molten steel outflow hole, 3 is the injection point, 4 is The weirs and 5 are long nozzles and show only one half of the tundish.
図１０に、溶鋼深さ比（Ｄin／Ｄout ）と介在物指数との関係について、堰の有無で比較して示す。図１０の縦軸に示す介在物指数は、前述した図８に示す介在物指数と同一であり、また、図１０に示す「堰なし」のデータは図８のデータと同一である。図１０に示すように、溶鋼深さ比（Ｄin／Ｄout ）を０．７０〜０．８５とした上で、更に堰を設置することで、介在物の浮上が促進され、清浄性に優れた溶鋼を鋳型に注入できることが確認できた。 FIG. 10 shows the relationship between the molten steel depth ratio (Din / Dout) and the inclusion index, with and without weirs. The inclusion index shown on the vertical axis in FIG. 10 is the same as the inclusion index shown in FIG. 8 described above, and the “no dam” data shown in FIG. 10 is the same as the data in FIG. As shown in FIG. 10, after setting the molten steel depth ratio (Din / Dout) to 0.70 to 0.85, further installing the weir promoted the floating of inclusions and was excellent in cleanliness. It was confirmed that molten steel could be poured into the mold.
但し、堰で遮られた部分の溶鋼がタンディッシュ内に残留する溶鋼量となり、最終的にはタンディッシュ付着地金とした回収され、鋳片歩留まり低下の原因となる。堰の高さを変更した試験の結果から、堰の高さを３５０ｍｍを超える高さにしても、介在物の低減効果が格段に向上することはなく、一方、鋳片歩留まりの低下が大きくなることから、堰の高さは５０〜３５０ｍｍの範囲が最適範囲であることが分かった。 However, the portion of the molten steel blocked by the weir becomes the amount of molten steel remaining in the tundish, and eventually is collected as tundish adhesion metal, which causes a reduction in the yield of the slab. From the test results of changing the height of the weir, even if the height of the weir exceeds 350 mm, the effect of reducing inclusions is not significantly improved, while the reduction in slab yield is increased. From this, it was found that the optimum height of the weir was in the range of 50 to 350 mm.
以上の結果から、タンディッシュの注入点の部位と溶鋼流出孔の部位との深さの差を適切に設定し、併せて注入点の部位の端部に上昇流を生じさせる堰を設置することで、溶鋼の清浄性が格段に向上し、介在物の少ない鋳片を得ることができることが確認できた。 Based on the above results, the depth difference between the tundish injection point part and the molten steel outflow hole part should be set appropriately, and a weir that will create an upward flow at the end of the injection point part should be installed. Thus, it was confirmed that the cleanliness of the molten steel was remarkably improved and a slab with few inclusions could be obtained.
次ぎに、これらの検討結果から得られた本発明に係るタンディッシュの詳細と、該タンディッシュを用いて溶鋼を連続鋳造して鋳片を製造する方法とを、図面に基づき説明する。図１１は、本発明に係るタンディッシュを用いて溶鋼を連続鋳造する状況を示す概略断面図である。尚、図１１に示す連続鋳造機は２ストランド型のスラブ連続鋳造機であり、タンディッシュの両端部に鋳型への溶鋼流出孔が設けられ、タンディッシュの中央部に取鍋からの溶鋼の注入点が配置されている。 Next, details of the tundish according to the present invention obtained from these examination results and a method for producing a slab by continuously casting molten steel using the tundish will be described with reference to the drawings. FIG. 11 is a schematic cross-sectional view showing a situation in which molten steel is continuously cast using the tundish according to the present invention. The continuous casting machine shown in FIG. 11 is a two-strand slab continuous casting machine, in which both ends of the tundish are provided with molten steel outflow holes to the mold, and molten steel is injected from the ladle at the center of the tundish. Dots are placed.
図１１において、外殻を鉄皮９とし、この鉄皮９の内側を耐火物１０で施工された本発明に係るタンディッシュ１が、タンディッシュカー（図示せず）に搭載されて鋳型１４の上方所定位置に配置され、また、タンディッシュ１の上方所定位置には、溶鋼１５を収容した取鍋６が配置されている。取鍋６の底部には上ノズル７が設置され、この上ノズル７の下面に接して、固定板８Ａ及び摺動板８Ｂからなるスライディングノズル８が溶鋼流量制御装置として設置され、更に、スライディングノズル８の下面に接して、大気を遮断するためのロングノズル５が接続されている。摺動板８Ｂは、往復型アクチュエーター（図示せず）に接続されており、往復型アクチュエーターの作動により、固定板８Ａと密に接触したまま移動し、固定板８Ａの開口部と摺動板８Ｂの開口部との開口部面積を調整することにより取鍋６からタンディッシュ１への溶鋼注入量が制御されるようになっている。また、タンディッシュ１の底部には、溶鋼流出孔２を形成する上ノズル１１が耐火物１０と嵌合して設置され、この上ノズル１１の下面に接して、固定板１２Ａ及び摺動板１２Ｂからなるスライディングノズル１２が溶鋼流量制御装置として設置され、更に、スライディングノズル１２の下面に接して、先端を鋳型１４の内部の溶鋼１５に浸漬させた浸漬ノズル１３が接続されている。摺動板１２Ｂは、往復型アクチュエーター（図示せず）に接続されており、往復型アクチュエーターの作動により、固定板１２Ａと密に接触したまま移動し、固定板１２Ａの開口部と摺動板１２Ｂの開口部との開口部面積を調整することによりタンディッシュ１から鋳型１４への溶鋼供給量が制御されるようになっている。 In FIG. 11, the tundish 1 according to the present invention in which the outer shell is an iron skin 9 and the inner side of the iron skin 9 is constructed with a refractory 10 is mounted on a tundish car (not shown) to A ladle 6 that houses molten steel 15 is disposed at a predetermined position above the tundish 1. An upper nozzle 7 is installed at the bottom of the ladle 6, and a sliding nozzle 8 composed of a fixed plate 8 </ b> A and a sliding plate 8 </ b> B is installed in contact with the lower surface of the upper nozzle 7 as a molten steel flow rate control device. A long nozzle 5 for blocking the atmosphere is connected to the lower surface of 8. The sliding plate 8B is connected to a reciprocating actuator (not shown), and is moved in close contact with the fixed plate 8A by the operation of the reciprocating actuator, and the opening of the fixed plate 8A and the sliding plate 8B The amount of molten steel injected from the ladle 6 to the tundish 1 is controlled by adjusting the opening area with the opening. Further, an upper nozzle 11 that forms a molten steel outflow hole 2 is fitted and installed at the bottom of the tundish 1 and is in contact with the lower surface of the upper nozzle 11 so as to be in contact with the fixed plate 12A and the sliding plate 12B. A sliding nozzle 12 is installed as a molten steel flow rate control device, and is further connected to an immersion nozzle 13 in contact with the lower surface of the sliding nozzle 12 and having its tip immersed in the molten steel 15 inside the mold 14. The sliding plate 12B is connected to a reciprocating actuator (not shown), and is moved in close contact with the fixed plate 12A by the operation of the reciprocating actuator, and the opening of the fixed plate 12A and the sliding plate 12B The amount of molten steel supplied from the tundish 1 to the mold 14 is controlled by adjusting the opening area with the opening.
タンディッシュ１の底面は、ロングノズル５の直下に位置する注入点３の部位が最も高くなり、一方、注入点３の両側に位置する溶鋼流出孔２の部位が最も低くなっている。注入点３の部位の底面及び溶鋼流出孔２の部位の底面はともに水平になっていて、注入点３を含む水平部から溶鋼流出孔２の部位を含む水平部にかけての底面は傾斜面となっており、注入点３を含む水平部の端部にはそれぞれ堰４が設置されている。 On the bottom surface of the tundish 1, the portion of the injection point 3 located immediately below the long nozzle 5 is the highest, while the portion of the molten steel outflow hole 2 located on both sides of the injection point 3 is the lowest. The bottom surface of the injection point 3 and the bottom surface of the molten steel outflow hole 2 are both horizontal, and the bottom surface from the horizontal part including the injection point 3 to the horizontal part including the molten steel outflow hole 2 is an inclined surface. A weir 4 is installed at each end of the horizontal portion including the injection point 3.
この場合、収容能力最大の溶鋼１５をタンディッシュ１に滞在させた際に、注入点３の部位の溶鋼深さ（Ｄin）と溶鋼流出孔２の部位の溶鋼深さ（Ｄout ）との溶鋼深さ比（Ｄin／Ｄout ）が０．７０〜０．８５の範囲になるように、つまり、最も深い位置の深さ（Ｄout ）と最も浅い位置の深さ（Ｄin）との深さの差が、最も深い位置の深さ（Ｄout ）に０．１５〜０．３０を乗算した範囲になるように、タンディッシュ１の底面の形状を設定する必要がある。また、堰４はタンディッシュ１の底部を全幅にわたって閉鎖する構造であり、堰４の高さ（Ｈ）は５０〜３５０ｍｍの範囲とする必要がある。堰４の厚みは特に規定する必要はなく、多数回の使用に耐えるような厚みを有することが好ましい。 In this case, when the molten steel 15 having the maximum capacity is allowed to stay in the tundish 1, the molten steel depth between the molten steel depth (Din) at the injection point 3 and the molten steel depth (Dout) at the molten steel outflow hole 2. The depth ratio (Din / Dout) is in the range of 0.70 to 0.85, that is, the depth difference between the deepest position depth (Dout) and the shallowest position depth (Din) is It is necessary to set the shape of the bottom surface of the tundish 1 so that the depth (Dout) of the deepest position is multiplied by 0.15 to 0.30. The weir 4 has a structure in which the bottom of the tundish 1 is closed over the entire width, and the height (H) of the weir 4 needs to be in the range of 50 to 350 mm. The thickness of the weir 4 does not need to be specified in particular, and it is preferable to have a thickness that can withstand many uses.
ここで、収容能力最大の溶鋼とは、タンディッシュ１に滞在する溶鋼１５の量が多少増減しても、タンディッシュ内の溶鋼１５がタンディッシュ１に設置される排出口からオーバーフローしないだけの最低限のフリーボードがタンディッシュ１の上部に形成される状態のときに収容される溶鋼量であり、通常、「８０トン容量のタンディッシュ」などと呼ぶ場合の「８０トン」がこれに該当する。尚、本発明を適用できるタンディッシュ１の容量は特に規定されるものではなく、２０〜１００トンの任意の容量のタンディッシュに適用することができる。また、溶鋼の注入流量も特に規定する必要はなく、１〜１０トン／分・ストランドの範囲の任意の注入量に対処することができる。 Here, the molten steel having the maximum capacity is the minimum that the molten steel 15 in the tundish 1 does not overflow from the discharge port installed in the tundish 1 even if the amount of the molten steel 15 staying in the tundish 1 slightly increases or decreases. This is the amount of molten steel that can be accommodated when a limited free board is formed in the upper part of the tundish 1, and usually corresponds to “80 tons” when referred to as “80 tons capacity tundish” or the like. . In addition, the capacity | capacitance of the tundish 1 which can apply this invention is not prescribed | regulated in particular, It can apply to the tundish of arbitrary capacities of 20-100 tons. Moreover, it is not necessary to prescribe | regulate especially the injection | pouring flow rate of molten steel, and can cope with the arbitrary injection | pouring amounts of the range of 1-10 tons / min.
取鍋６からタンディッシュ１に溶鋼１５を注入し、タンディッシュ１に溶鋼１５を滞在させた状態で、タンディッシュ１から溶鋼流出孔２を介して鋳型１４に溶鋼１５を供給する。鋳型１４に供給された溶鋼１５は、鋳型１４と接触して冷却されて凝固シェル１７を形成し、外殻を凝固シェル１７として内部を未凝固の溶鋼１５とする鋳片１６は鋳型１４の下方に連続的に引き抜かれ、やがて中心部まで完全に凝固して鋳片が製造される。取鍋６からタンディッシュ１への溶鋼１５の注入流はロングノズル５によって大気と遮断され、タンディッシュ１から鋳型１４への溶鋼１５の注入流は浸漬ノズル１３によって大気と遮断されている。 Molten steel 15 is poured into the tundish 1 from the ladle 6, and the molten steel 15 is supplied from the tundish 1 to the mold 14 through the molten steel outflow hole 2 while the molten steel 15 stays in the tundish 1. The molten steel 15 supplied to the mold 14 is cooled in contact with the mold 14 to form a solidified shell 17, and the slab 16 having an outer shell as the solidified shell 17 and an inside of the unsolidified molten steel 15 is below the mold 14. The slab is produced by continuously solidifying to the central part and eventually solidifying. An injection flow of the molten steel 15 from the ladle 6 to the tundish 1 is blocked from the atmosphere by the long nozzle 5, and an injection flow of the molten steel 15 from the tundish 1 to the mold 14 is blocked from the atmosphere by the immersion nozzle 13.
尚、比（Ｄin／Ｄout ）がこの範囲を満足するようにタンディッシュ１の形状を設計することで、最終的にタンディッシュ１においては前述した介在物低減効果を得ることができることを確認している。 In addition, by designing the shape of the tundish 1 so that the ratio (Din / Dout) satisfies this range, it has been confirmed that the above-described inclusion reduction effect can be finally obtained in the tundish 1. Yes.
このようにして鋳造することで、例えば、連々鋳の取鍋交換時に取鍋６の溶鋼上に存在するスラグ１８が溶鋼１５とともにタンディッシュ１に流出しても、タンディッシュ１においてスラグ１８は溶鋼中を効率的に浮上して溶鋼１５と分離されるとともに溶鋼流出孔２の近傍での巻き込みも防止されるため、介在物が少なく、極めて清浄性の高い鋳片１６を得ることができる。本発明のタンディッシュ１を用いることで、溶鋼中に懸濁したスラグ１８のみならず、アルミナなどの脱酸生成物も効率的に浮上分離させることができる。また、品質厳格材の連続鋳造においては、スラグ１８のタンディッシュ１への流出を防止するために、取鍋６に数トン〜十数トンの溶鋼１５を残留させて取鍋６からの注入を終了する場合があるが、本発明のタンディッシュ１を用いる場合には、このようなことを実施しなくても清浄性に優れた鋳片１６を得ることができ、鋳片歩留まりを向上させることができる。 By casting in this way, for example, even if the slag 18 existing on the molten steel of the ladle 6 flows out to the tundish 1 together with the molten steel 15 when the ladle is continuously cast, the slag 18 is molten in the tundish 1. Since the inside of the molten steel 15 is efficiently levitated and separated from the molten steel 15 and the entanglement in the vicinity of the molten steel outflow hole 2 is also prevented, the slab 16 having few inclusions and extremely high cleanliness can be obtained. By using the tundish 1 of the present invention, not only the slag 18 suspended in the molten steel but also deoxidation products such as alumina can be efficiently levitated and separated. Further, in continuous casting of strict quality materials, in order to prevent the slag 18 from flowing out to the tundish 1, several tons to tens of tons of molten steel 15 is left in the ladle 6 and injected from the ladle 6. However, when the tundish 1 of the present invention is used, the slab 16 having excellent cleanliness can be obtained without carrying out such a thing, and the slab yield can be improved. Can do.
尚、本発明は上記説明に限るものではなく、種々の変更が可能である。例えば、上記説明では２ストランドの連続鋳造機について説明したが、単ストランドであっても、また３ストランド以上であっても、上記説明に準じて本発明を適用することができる。 The present invention is not limited to the above description, and various modifications can be made. For example, in the above description, a two-strand continuous casting machine has been described, but the present invention can be applied in accordance with the above description regardless of whether it is a single strand or three or more strands.
容量が８０トンである、１．２ｍ幅の２ストランド型のタンディッシュにおいて、溶鋼流出孔の部位の溶鋼深さを１．５ｍの一定とした上で注入点の部位の溶鋼深さを変更し、更にはタンディッシュの底部に堰を設置し、このタンディッシュを用いて低炭素Ａｌキルド鋼を連々鋳し、スラブ鋳片を製造した。鋳型への溶鋼注入量は５トン／分とし、鋳型内の１／４幅位置の湯面における溶鋼流速を０．２ｍ／秒となるように電磁力による制御を実施した。鋳造後、取鍋交換時に該当する部位のスラブ鋳片を鋳片の表面手入れをすることなく、熱間圧延及び冷間圧延して薄鋼板を製造し、得られた薄鋼板で介在物個数を調査して、タンディッシュ形状と取鍋交換時のスラブ鋳片から圧延された薄鋼板の介在物量との関係を調査する試験を実施した。使用した堰は、高さが５０ｍｍ、２００ｍｍ、３５０ｍｍ、４５０ｍｍの４水準であり、タンディッシュ底部を全幅にわたって閉鎖する構造であり、この堰を、注入点を含む水平部の端部に設置した。連々鋳時の取鍋交換は、取鍋内のスラグがタンディッシュに流出したことを確認した後に、取鍋のスライディングノズルを閉塞する方法によって行った。 In a 1.2m wide two-strand tundish with a capacity of 80 tons, the molten steel depth at the injection point was changed after the molten steel depth at the molten steel outlet hole was kept constant at 1.5m. Furthermore, weirs were installed at the bottom of the tundish, and low carbon Al killed steel was cast continuously using this tundish to produce a slab slab. The amount of molten steel injected into the mold was 5 tons / minute, and control by electromagnetic force was performed so that the molten steel flow velocity at the molten metal surface at the 1/4 width position in the mold was 0.2 m / sec. After casting, the slab slab of the corresponding part at the time of ladle replacement is hot-rolled and cold-rolled to manufacture a thin steel plate without cleaning the surface of the slab, and the number of inclusions is determined with the obtained thin steel plate. A study was conducted to investigate the relationship between the tundish shape and the amount of inclusions in the thin steel sheet rolled from the slab slab when the ladle was replaced. The weirs used had four levels of 50 mm, 200 mm, 350 mm, and 450 mm in height, and had a structure in which the tundish bottom was closed over the entire width, and this weir was installed at the end of the horizontal part including the injection point. The ladle exchange at the time of continuous casting was performed by a method of closing the sliding nozzle of the ladle after confirming that the slag in the ladle had flowed into the tundish.
表２に、使用したタンディッシュの形状、堰の有無、使用した堰の高さ、及び試験結果を示す。表２において、品質評点は、介在物センサーによって薄鋼板の介在物個数を検査した結果に基づくもので、評点Ａは検出される介在物個数が単位面積当たり１個未満、評点Ｂは単位面積当たり１個以上２個未満、評点Ｃは単位面積当たり２個以上の場合であり、評点Ａ及び評点Ｂが製品に使用可能である。歩留まり評点はタンディッシュに残留する溶鋼量から定め、○は歩留まりの低下がない或いは極めて少なく良好なもの、△はかなりの歩留まりの低下が認められるものであり、総合評点は、品質評点及び歩留まり評点の双方から判定したもので、○は良好、△は普通、×は不良として表示している。また、備考欄には、本発明の範囲の条件を「本発明例」と記し、それ以外を「比較例」として記している。 Table 2 shows the shape of the tundish used, the presence or absence of a weir, the height of the weir used, and the test results. In Table 2, the quality score is based on the result of inspection of the number of inclusions in the thin steel plate by the inclusion sensor. The score A is less than 1 inclusion per unit area, and the score B is per unit area. 1 or more and less than 2, and score C is 2 or more per unit area, and score A and score B can be used for the product. Yield score is determined from the amount of molten steel remaining in the tundish, ○ indicates that there is no or very little decrease in yield, and △ indicates that a significant decrease in yield is observed. The overall score is the quality score and yield score. ◯ is indicated as good, Δ is normal, and X is indicated as bad. In the remarks column, the conditions within the scope of the present invention are described as “examples of the present invention”, and the other conditions are described as “comparative examples”.
表２に示すように、本発明の範囲の条件では、品質及び歩留まりともに良好な成績であった。これに対して、本発明の範囲を外れた条件では、品質及び歩留まりのうちのどちらかが満足できるレベルに至らなかった。 As shown in Table 2, both the quality and the yield were good under the conditions within the scope of the present invention. On the other hand, under conditions outside the scope of the present invention, either quality or yield did not reach a satisfactory level.
本技術は、実施例１の条件のみによらず、下記条件においても同様の効果があることを確認した。即ち、タンディッシュ重量が２０〜１００トン、最大深さが０．７〜２．０ｍのタンディッシュで効果を有する。最大深さが０．７ｍ未満の場合には、取鍋交換時に溶鋼流出孔に生成する渦、及びそれに伴うスラグ巻き込みの影響が避けられず、効果は得られなかった。 It was confirmed that the present technology has the same effect not only under the conditions of Example 1 but also under the following conditions. That is, it is effective in a tundish having a tundish weight of 20 to 100 tons and a maximum depth of 0.7 to 2.0 m. When the maximum depth was less than 0.7 m, the effect of the vortex generated in the molten steel outflow hole at the time of ladle replacement and the entrainment of slag accompanying it could not be avoided, and the effect could not be obtained.
１ タンディッシュ
２ 溶鋼流出孔
３ 注入点
４ 堰
５ ロングノズル
６ 取鍋
７ 上ノズル
８ スライディングノズル
９ 鉄皮
１０ 耐火物
１１ 上ノズル
１２ スライディングノズル
１３ 浸漬ノズル
１４ 鋳型
１５ 溶鋼
１６ 鋳片
１７ 凝固シェル
１８ スラグ
DESCRIPTION OF SYMBOLS 1 Tundish 2 Molten steel outflow hole 3 Injection point 4 Weir 5 Long nozzle 6 Ladle 7 Upper nozzle 8 Sliding nozzle 9 Iron skin 10 Refractory 11 Upper nozzle 12 Sliding nozzle 13 Immersion nozzle 14 Mold 15 Molten steel 16 Slab 17 Solidified shell 18 Slug
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| CN108393480A (en) * | 2018-05-17 | 2018-08-14 | 山东钢铁股份有限公司 | A kind of herringbone fashion suitable for Profiled Slab CCM full guard casting shunts the mouth of a river |
| CN112517897A (en) * | 2020-11-19 | 2021-03-19 | 东北大学 | Split type tundish turbulence controller |
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| CN112517897B (en) * | 2020-11-19 | 2021-08-31 | 东北大学 | Split type tundish turbulence controller |
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