GB2170131A - Molten steel pouring nozzle - Google Patents
Molten steel pouring nozzle Download PDFInfo
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- GB2170131A GB2170131A GB08530807A GB8530807A GB2170131A GB 2170131 A GB2170131 A GB 2170131A GB 08530807 A GB08530807 A GB 08530807A GB 8530807 A GB8530807 A GB 8530807A GB 2170131 A GB2170131 A GB 2170131A
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- molten steel
- nozzle
- pouring nozzle
- refractory
- steel pouring
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- C—CHEMISTRY; METALLURGY
- C04—CEMENTS; CONCRETE; ARTIFICIAL STONE; CERAMICS; REFRACTORIES
- C04B—LIME, MAGNESIA; SLAG; CEMENTS; COMPOSITIONS THEREOF, e.g. MORTARS, CONCRETE OR LIKE BUILDING MATERIALS; ARTIFICIAL STONE; CERAMICS; REFRACTORIES; TREATMENT OF NATURAL STONE
- C04B35/00—Shaped ceramic products characterised by their composition; Ceramics compositions; Processing powders of inorganic compounds preparatory to the manufacturing of ceramic products
- C04B35/01—Shaped ceramic products characterised by their composition; Ceramics compositions; Processing powders of inorganic compounds preparatory to the manufacturing of ceramic products based on oxide ceramics
- C04B35/44—Shaped ceramic products characterised by their composition; Ceramics compositions; Processing powders of inorganic compounds preparatory to the manufacturing of ceramic products based on oxide ceramics based on aluminates
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- B—PERFORMING OPERATIONS; TRANSPORTING
- B22—CASTING; POWDER METALLURGY
- B22D—CASTING OF METALS; CASTING OF OTHER SUBSTANCES BY THE SAME PROCESSES OR DEVICES
- B22D41/00—Casting melt-holding vessels, e.g. ladles, tundishes, cups or the like
- B22D41/50—Pouring-nozzles
- B22D41/52—Manufacturing or repairing thereof
- B22D41/54—Manufacturing or repairing thereof characterised by the materials used therefor
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- Chemical & Material Sciences (AREA)
- Manufacturing & Machinery (AREA)
- Ceramic Engineering (AREA)
- Materials Engineering (AREA)
- Structural Engineering (AREA)
- Organic Chemistry (AREA)
- Mechanical Engineering (AREA)
- Casting Support Devices, Ladles, And Melt Control Thereby (AREA)
- Compositions Of Oxide Ceramics (AREA)
Abstract
A molten steel pouring nozzle having along the axis thereof an inner bore through which molten steel flows. At least a part of the molten steel pouring nozzle is formed with a refractory consisting of at least 30 wt.% calcium oxide and at least one of magnesium oxide and aluminum oxide such that the melting point of the refractory falls within the region of at least 2,200 DEG C in the CaO-MgO-Al2O3 ternary phase diagram. In use, deposition of Al2O3 from the steel on to such a refractory results in a reaction between the refractory and the deposit, leading to production of low-melting point products which readily dissolve in the steel. Thus, the nozzle does not become clogged. Further, if the nozzle is installed as a flow-regulator in a weir of a tundish, the low-melting point product floats to the surface in the tundish thus making it possible to remove Al2O3 from the steel. <IMAGE>
Description
SPECIFICATION
Molten steel pouring nozzle
Field of the invention
The present invention relates to a molten steel pouring nozzle, which is secured to a molten steel receiving vessel such as a tundish or a ladle.
Background of the invention
Continuous casting of molten steel is carried out, for example, by pouring molten steel, received from a ladle into a tundish, through a molten steel pouring nozzle secured to the bottom wall of the tundish, into a vertical mold arranged below the molten steel pouring nozzle to form a cast steel strand, and continuously withdrawing the thus formed cast steel strand into a single long strand.
Figure 1 is a schematic vertical sectional view illustrating a tundish provided with a conventional molten steel pouring nozzle as a tundish nozzle and a conventional molten steel pouring nozzle as an immersion nozzle. As shown in Figure 1, a molten steel pouring nozzle 3 as a tundish nozzle, having along the axis thereof an inner bore 4 through which molten steel flows, is secured in the bottom wall 2 of a tundish 1. A molten steel pouring nozzle 5 as an immersion nozzle, having along the axis thereof an inner bore 6 through which molten steel flows, is fitted to the lower end of the molten steel pouring nozzle 3 as tundish nozzle so as to project vertically and downwardly. The molten steel pouring nozzle 5 as the immersion nozzle has a length sufficient to allow the lower end portion thereof to be immersed into molten steel in a mold not shown during operation.The inner bore 4 of the molten steel pouring nozzle 3 as the tundish nozzle communicates with the inner bore 6 of the molten steel pouring nozzle 5 as the immersion nozzle.
The conventional molten steel pouring nozzle 3 as the tundish nozzle and the conventional molten steel pouring nozzle 5 as the immersion nozzle as described above are formed with any refractory excellent in erosion resistance against molten steel such as zirconia refractory, silica refractory, zirconia-silica refractory, alumina-graphite refractory or alumina silica refractory.
Figure 2 is a schematic vertical sectional view illustrating a tundish provided with another conventional molten steel pouring nozzle as an immersion nozzle. As shown in Figure 2, a molten steel pouring nozzle 7 as an immersion nozzle, having along the axis thereof an inner bore 8 through which molten steel flows, is secured to the bottom wall 2 of a tundish 1 so as to project vertically and downwardly. The upper portion 7a of the molten steel pouring nozzle 7 as the immersion nozzle is formed with a refractory particularly excellent in thermal shock resistance, and the remaining portion 7c other than the upper portion 7a is formed with any refractory excellent in erosion resistance against molten steel as described above.
Figure 3 is a schematic vertical sectional view illustrating a tundish provided with still another conventional molten steel pouring nozzle as an immersion nozzle. As shown in Figure 3, a molten steel pouring nozzle 7 as an immersion nozzle, having along the axis thereof an inner bore 8 through which molten steel flows, is secured to the bottom wall 2 of a tundish 1 so as to project vertically and downwardly. The upper portion 7b of the inner surface portion of the molten steel pouring nozzle 7 as the immersion nozzle, which forms the inner bore 8, is formed with a refractory particularly excellent in thermal shock resistance, and the remaining portion 7c other than the upper portion 7b of the inner surface portion is formed with any refractory excellent in erosion resistance against molten steel as described above.
When pouring molten steel received in the tundish into a mold through any one of the above-mentioned conventional molten steel pouring nozzles, there may occur the problem that fine aluminum oxide present in molten steel deposits and accumulates onto the inner surface of the molten steel pouring nozzle, which forms the inner bore, and clogs up the inner bore. Such a problem occurs also when molten steel received in the ladle is poured into the tundish or the mold through the above-mentioned molten steel pouring nozzle as the ladle nozzle secured in the bottom wall of the ladle.
Causes of the presence of aluminum oxide in molten steel are as follows:
(1) Aluminum oxide contained in the lining bricks of a molten steel receiving vessel such as a tundish or a ladle is entangled into molten steel in the molten steel receiving vessel along with erosion of the lining bricks.
(2) In the case of aluminum-killed steel, aluminum added to the molten steel produces aluminum oxide through reaction with oxygen in molten steel.
(3) In the case of aluminum-killed steel, aluminum added to molten steel produces aluminum oxide through reaction with iron oxide in the molten slag floating on the molten steel surface.
(4) Aluminum present in molten steel produces aluminum oxide through reaction with oxygen in the air.
While part of aluminum oxide entangled or produced by the causes as described above floats on the molten steel surface and is separated from molten steel, most of aluminum oxide remains in molten steel in the state of fine particles with a size of several microns. Consequently, when molten steel in a molten steel receiving vessel is poured, for example, into a mold through the conventional molten steel pouring nozzle, aluminum oxide present in molten steel deposits and accumulates onto the inner surface of the molten steel pouring nozzle, which forms the inner bore, and clogs up the inner bore.
As the method for preventing clogging up of the inner bore of the conventional molten steel pouring nozzle caused by aluminum oxide present in the molten steel, the following methods are known:
(1) Preventing aluminum present in molten steel from reacting with oxygen in the air to produce aluminum oxide, by preventing molten steel from contacting with the air when molten steel in a ladle is poured into a tundish, and when molten steel in the tundish or the ladle is poured into a mold.
(2) Preventing temperature decrease of molten steel flowing through the inner bore of a molten steel pouring nozzle by heating the molten steel pouring nozzle, to prevent aluminum oxide present in molten steel from precipitating and depositing onto the inner surface of the molten steel pouring nozzle, which forms the inner bore.
(3) Ejecting an inert gas from the inner surface of the molten steel pouring nozzle, which forms an inner bore, toward molten steel flowing through the inner bore, to prevent aluminum oxide present in molten steel from depositing and accumulating onto the inner surface.
Figures 4 and 5 are schematic vertical sectional views each illustrating a tundish provided with a conventional molten steel pouring nozzle as a tunsish nozzle having such an inert gas ejecting function and a conventional molten steel pouring nozzle as an immersion nozzle.
As shown in Figure 4, a molten steel pouring nozzle 9 as a tundish nozzle, having along the axis thereof an inner bore 10 through which molten steel flows, is secured in the bottom wall 2 of a tundish 1.
The molten steel pouring nozzle 5 as the immersion nozzle identical to that shown in Figure 1 is fitted to the lower end of the molten steel pouring nozzle 9 as the tundish nozzle so as to project vertically and downwardly. The molten steel pouring nozzle 9 as the tundish nozzle is provided with an annular cavity 11, near the inner bore 10 thereof, for ejecting inert gas toward molten steel flowing through the inner bore 10. Inert gas introduced through an inert gas supply pipe 12 into the annular cavity 11 is ejected toward molten steel flowing through the inner bore 10, thereby preventing aluminum oxide from depositing onto the inner surface of the molten steel pouring nozzle 9 as the tundish nozzle, which forms the inner bore 10. A molten steel pouring nozzle 9 as a tundish nozzle shown in Figure 5 is formed with a porous refractory.Inert gas introduced through an inert gas supply pipe 12 into the molten steel pouring nozzle 9 made of porous refractory as the tundish nozzle, is ejected toward molten steel flowing through the inner bore 10, thereby preventing aluminum oxide from depositing onto the inner surface of the molten steel pouring nozzle 9 as the tundish nozzle, which forms the inner bore 10.
(4) Removing aluminum oxide present in molten steel received in a tundish within the tundish by the steps of: arranging in the tundish at least one vertical refractory weir which has a plurality of horizontal molten steel pouring nozzles as through-holes for passing molten steel therethrough; rectifying the flow of molten steel while molten steel poured from a ladle into the tundish passes through the plurality of horizontal molten steel pouring nozzles as the through-holes of the at least one weir; and causing aluminum oxide present in molten steel to deposit onto the inner surfaces of the plurality of horizontal molten steel pouring nozzles as the through-holes, thereby removing aluminum oxide from molten steel.
However, when continuously casting molten aluminum-killed steel containing at least 0.003 wt.% Sol.AI into a cast strand of a small cross-sectional area having a side of up to 200 mm by the use of a smalldiameter conventional molten steel pouring nozzle as the tundish nozzle or the immersion nozzle having inner bore diameter of from 10 to 20 mm, it is impossible, even by any of the above-mentioned methods (1) to (4), to prevent aluminum oxide present in molten steel from depositing onto the inner surface of the conventional molten steel pouring nozzle as the tundish nozzle or the immersion nozzle, and hence to prevent clogging up of the inner bore of the conventional molten steel pouring nozzle caused by aluminum oxide deposited and accumulated onto the inner surface of the molten steel pouring nozzle.It has therefore conventionally been believed impossible to continuously cast molten aluminum-killed steel as described above into a cast steel strand of a small cross-sectional area by the use of the above-mentioned small-diameter conventional molten steel pouring nozzle as the tundish nozzle or the immersion nozzle.
Under such circumstances, there is a strong demand for the development of a molten steel pouring nozzle as a tundish nozzle or an immersion nozzle, which permits prevention of clogging up of the inner bore of the molten steel pouring nozzle caused by the deposition of aluminum oxide present in molten steel flowing through the inner bore, even when molten aluminum-killed steel having a high Sol.AI content is poured into a mold through the inner bore of a small diameter of the molten steel pouring nozzle.
However, such a molten steel pouring nozzle has not as yet been proposed.
Summary of the invention
A principal object of the present invention is therefore to provide a molten steel pouring nozzle as a tundish nozzle or an immersion nozzle, which permits prevention of clogging up of the inner bore of the molten steel pouring nozzle caused by the deposition of aluminum oxide present in molten steel flowing through the inner bore, even when molten aluminum-killed steel having a high Sol.AI content is poured into a mold through the inner bore of a small diameter of the molten steel pouring nozzle.
Another object of the present invention is to provide a molten steel pouring nozzle as a through-hole, which is fitted in a vertical refractory weir arranged in a tundish, and which permits removal of aluminum oxide present in molten steel flowing through the inner bore of the molten steel pouring nozzle.
In accordance with one of the features of the present invention, there is provided a molten steel pouring nozzle having along the axis thereof an inner bore through which molten steel flows, characterized in that:
at least a part of said molten steel pouring nozzle is formed with a refractory consisting essentially of at least 30 wt.% calcium oxide and at least one of magnesium oxide and aluminum oxide; and
said refractory contains at least one of said magnesium oxide and said aluminum oxide so that the melting point of said refractory falls within the region of at least 2,2000C in the CaO-MgO-AI203 ternary phase diagram.
Brief description of the drawings
Figure 1 is a schematic vertical sectional view illustrating a tundish provided with a conventional molten steel pouring nozzle as a tundish nozzle and a conventional molten steel pouring nozzle as an immersion nozzle;
Figure 2 is a schematic vertical sectional view illustrating a tundish provided with another conventional molten steel pouring nozzle as an immersion nozzle;
Figure 3 is a schematic vertical sectional view illustrating a tundish provided with still another conventional molten steel pouring nozzle as an immersion nozzle;
Figure 4 is a schematic vertical sectional view illustrating a tundish provided with a conventional molten steel pouring nozzle as a tundish nozzle having an inert gas ejecting function and a conventional molten steel pouring nozzle as an immersion nozzle;;
Figure 5 is a schematic vertical sectional view illustrating a tundish provided with another conventional molten steel pouring nozzle as a tundish nozzle having an inert gas ejecting function and a conventional molten steel pouring nozzle as an immersion nozzle;
Figure 6 is a CaO-MgO-AI2O3 ternary phase diagram illustrating the chemical composition of the refractory forming the molten steel pouring nozzle of the present invention;
Figure 7 is a schematic vertical sectional view illustrating a first embodiment of the molten steel pouring nozzle as a tundish nozzle or a ladle nozzle of the present invention;
Figure 8 is a schematic vertical sectional view illustrating a second embodiment of the molten steel pouring nozzle as a tundish nozzle or a ladle nozzle of the present invention;;
Figure 9 is a schematic vertical sectional view illustrating a third embodiment of the molten steel pouring nozzle as a tundish nozzle or a ladle nozzle of the present invention;
Figure 10 is a schematic vertical sectional view illustrating a fourth embodiment of the molten steel pouring nozzle as an immersion nozzle of the present invention;
Figure ii is a schematic vertical sectional view illustrating a fifth embodiment of the molten steel pouring nozzle as an immersion nozzle of the present invention; and
Figure 12 is a schematic vertical sectional view illustrating a sixth embodiment of the molten steel pouring nozzle as a through-hole of the present invention, which is horizontally fitted in each of vertical weirs arranged in a tundish.
Detailed description of preferred embodiments
From the above-mentioned point of view, we carried out extensive studies to develop a molten steel pouring nozzle as a tundish nozzle or an immersion nozzle, which permits prevention of clogging up of the inner bore of the molten steel pouring nozzle caused by the deposition of aluminum oxide present in molten steel flowing through the inner bore, even when molten aluminum-killed steel having a high
Sol.Al content is poured into a mold through the inner bore of a small diameter of the molten steel pouring nozzle.
As a result, we obtained the following finding: a refractory which consists essentially of at least 30 wt.% calcium oxide and at least one of magnesium oxide and aluminum oxide and which contains at least one of said magnesium oxide and said aluminum oxide so that the melting point of the refractory falls within the region of at least 2,200"C in the CaO-MgO-AI203 ternary phase diagram, produces a compound of a low melting point, a eutectic mixture of a low melting point and a mixture of compounds of a low melting point (hereinafter referred to as the "low-melting-point compound and mixture") listed below on the interface between the refractory and molten steel through reaction with aluminum oxide present in molten steel::
(1) mCaO-nA 1203 compound;
(2) Eutectic mixture of MgO and mCaO-nAI203; (3) Mixture of MgO, CaO and mCaO nAI203; (4) Mixture of MgO, MgOAI2O and mCaO nAI203; (5) Mixture of MgO.Al2O and mCaO nAi203; (6) Mixture of CaO and mCaO-nAI203; and
(7) Mixture of a plurality of mCaOnAl2O3 with different m and n values.
Table 1 shows the molecular formula, the chemical composition and the melting point of the abovementioned low-melting-point compound and mixture.
TABLE 1
Chemical Melting
No. Molecular formula composition (wt%) point CaO MgO A /203 Al2O3 ( C) 1 CaOAI2O 35.4 - 64.6 1600
2 5CaO-3AI203 47.8 - 52.2 1455
3 3CaO Al203 62.2 - 37.8 1535
4 MgO,3CaO A1203,5CaO 1203 46.0 6.3 47.7 1345
5 MgO,5CaO.3Al2O3,CaO.Al2O3 41.5 6.7 51.8 1345
6 MgO+CaOt3caO Al203 51.5 6.2 42.3 1450
7 MgO+MgO.Al2O2+CaO.A12O3 45.7 6.9 52.4 1370
8 MgO-AI203+CaO-Ai203+3CaO-5AI203 33.3 3.5 63.2 1550
9 CaO+3CaO Al203 59.0 - 41.0 1535
10 3CaO Al203+5CaO 3A1203 50.0 - 50.0 1395
11 5CaO-3AI203+CaO-AI203 47.0 - 53.0 1400
12 CaO.Al2O3+3CaO.5Al2O3 33.5 - 66.5 1590
In the CaO-MgO-Al2O3 ternary phase diagram shown in Figure 6, C represents the point of 100 wt.%
CaO, M represents the point of 100 wt.% MgO, and A represents the point of 100 wt.% A1203. The region
E including the point C is the crystallization region of lime; the region B including the point M is the crystallization region of periclase; and the region D including the point A is the crystallization region of spinel. The line G is the eutectic line of lime and periclase, and the line F is the eutectic line of periclase and spinel. The dotted lines are melting isothermal lines drawn at intervals of 100 C.
As is known frorn the above, in a molten steel pouring nozzle having along the axis thereof an inner bore through which molten steel flows, and formed with a refractory which consists essentially of at least 30 wt.% calcium oxide and at least one of magnesium oxide and aluminum oxide and which contains at least one of said magnesium oxide and said aluminum oxide so that the melting point of the refractory falls within the region of at least 2,2000C in the CaO-MgO-AI203 ternary phase diagram, even when aluminum oxide present in molten steel deposits onto the inner surface of the molten steel pouring nozzle, which forms the inner bore, the refractory having the above-mentioned chemical composition reacts with said aluminum oxide to produce the low-melting-point compound and mixture on the interface between the refractory and molten steel, whereby the deposited aluminum oxide easily dissolves.
The present invention was made on the basis of the above-mentioned findings. At least a part of the molten steel pouring nozzle of the present invention is formed with a refractory which consists essentially of at least 30 wt.% calcium oxide and at least one of magnesium oxide and aluminum oxide, and the refractory contains at least one of said magnesium oxide and said aluminum oxide so that the melting point of the refractory falls within the region of at least 2,200 C in the CaO-MgO-Al2O3 ternary phase diagram.
The reasons why the chemical composition of the refractory which forms the molten steel pouring nozzle of the present invention is defined as mentioned above are described below.
With a calcium oxide content under 30 wt.%, it is impossible for the refractory forming the molten steel pouring nozzle to react with aluminum oxide present in molten steel, and to quickly produce the low melting-point compound and mixture mentioned above on the interface between the refractory and molten steel.
On the other hand, when the content of at least one of magnesium oxide and aluminum oxide is outside the region in the CaO-MgO-AI203 ternary phase diagram in which the melting point of the refractory is at least 2,2000C, the refractory forming the molten steel pouring nozzle tends to be easily eroded through contact with molten steel and can not bear operations for a long period of time.
The shadowed portion in the CaO-MgO-AI203ternary phase diagram as shown in Figure 6 represents the range of the chemical composition of the refractory forming the molten steel pouring nozzle of the present invention.
Table 2 shows examples of the chemical composition and melting point of the refractory forming the molten steel pouring nozzle of the present invention.
TABLE 2
Chemical composition ('wit%) Melting
No. point pC) CaO MgO Al3O3 1 40.5 40.5 19.0 2,300
2 44.5 44.5 11.0 2,400
3 75.5 10.5 14.0 2,200
4 50.0 45.0 5.0 2,430
5 45.0 50.0 5.0 2,480
6 80.0 10.0 10.0 2,320
7 85.0 10.0 5.0 2,420
8 84.5 15.5 - 2.480
9 50.0 50.0 - 2,470
10 88.0 - 12.0 2,400
11 70.0 30.0 - 2,410
The materials for the refractory forming the molten steel pouring nozzle of the present invention may be any of:
(1) a mixture of calcium oxide and at least one of magnesium oxide and aluminum oxide;
(2) a premelt produced prepared by melting a mixture of calcium oxide and at least one of magnesium oxide and aluminum oxide, solidying by cooling the resultant molten mixture, and then pulverising the solidified mixture; and
(3) a natural ore comprising calcium oxide and at least one of magnesium oxide and aluminum oxide.
When manufacturing the molten steel pouring nozzle of the present invention, it is desirable to form the refractory comprising any of the above-mentioned materials into a molten steel pouring nozzle having a prescribed shape by a known method, and then fire the formed body thus obtained.
Uses of the molten steel pouring nozzle of the present invention are as follows:
(1) the use as a tundish nozzle which is secured in the bottom wall of a tundish, for pouring molten steel in the tundish into a mold;
(2) the use as an immersion nozzle which is fitted to the lower end of the above-mentioned molten steel pouring nozzle as the tundish nozzle so as to project vertically and downwardly, for pouring molten steel in the tundish into a mold;
(3) the use as a ladle nozzle which is secured in the bottom wall of a ladle, for pouring molten steel in the ladle into a tundish or a mold; and
(4) the use as through-holes which are horizontally provided in each of vertical weirs arranged in a tundish, for passing molten steel therethrough.
Now, the molten steel pouring nozzle of the present invention is described with reference to the drawings.
Figure 7 is a schematic vertical sectional view illustrating a first embodiment of the molten steel pouring nozzle of the present invention. A molten steel pouring nozzle 13 of the first embodiment is used as a tundish nozzle which is secured in the bottom wall of a tundish or as a ladle nozzle which is secured in the bottom wall of a ladle. As shown in Figure 7, the entirety of the molten steel pouring nozzle 13 as the tundish nozzle or the ladle nozzle, having along the axis thereof an inner bore 14 through which molten steel flows, is formed with a refractory having the chemical composition as described above, which produces the low-melting-point compound and mixture.
According to the molten steel pouring nozzle 13 as the tundish nozzle or the ladle nozzle of the first embodiment, aluminum oxide present in molten steel never deposits onto the inner surface of the molten steel pouring nozzle 13, which forms the inner bore 14. When the inner bore 14 may be expanded by the production of the low-melting-point compound and mixture, it is desirable to provide a publicly known control apparatus of molten steel flow rate such as a sliding nozzle at the lower end of the molten steel pouring nozzle 13.
Figure 8 is a schematic vertical sectional view illustrating a second embodiment of the molten steel pouring nozzle of the present invention. A molten steel pouring nozzle 13 of the second embodiment is also used as the tundish nozzle or the ladle nozzle. As shown in Figure 8, the molten steel pouring nozzle 13 as the tundish nozzle or the ladle nozzle, having along the axis thereof an inner bore 14 through which molten steel flows, comprises an upper half portion 13a forming the upper part 14a of the inner bore 14 and a lower half portion 13b forming the lower part 14b of the inner bore 14.The upper half portion 13a onto which aluminum oxide present in molten steel tends to deposit, is formed with a refractory having the chemical composition as described above, which produces the low-melting-point compound and mixture, whereas the lower half portion 13b, onto which aluminum oxide relatively hardly deposits, is formed with any of the publicly known refractories excellent in erosion resistance against molten steel, having the following chemical composition:
(1) for example, zirconia refractory comprising 95 wt.% ZrO2;
(2) for example, silica refractory comprising 99 wt.% SiO2;
(3) for example, zirconia-silica refractory comprising 33 wt.% SiO2, 1.5 wt.% Awl203 and 65 wt.% ZrO2;
(4) for example, aluminum-graphite refractory comprising 60 wt.% Al203 and 33 wt.% C; and
(5) for example, aluminum-silica refractory comprising 72 wt.% Awl203 and 24 wt.% SiO2.
According to the molten steel pouring nozzle 13 as the tundish nozzle or the ladle nozzle of the second embodiment, aluminum oxide present in molten steel never deposits onto the inner surface of the upper half portion 13a of the molten steel pouring nozzle 13, which forms the upper part 14a of the inner bore 14, onto which the aluminum oxide tends to easily deposit. In addition, even when the upper part 14a of the inner bore 14 is expanded by the production of the low-melting-point compound and mixture, the lower part 14b of the inner bore 14 is relatively hardly expanded, since the lower half portion 13b of the molten steel pouring nozzle 13 is formed with a refractory excellent in erosion resistance against molten steel, and it is thus possible to keep constant the flow rate of molten steel flowing through the inner bore 14.When the upper part 14a of the inner bore 14 has a funnel shape as shown in Figure 8, the lower portion of the upper part 14a of the inner bore 14 should have the same diameter as that of the lower part 14b of the inner bore 14.
Since the molten steel pouring nozzle 13 as the tundish nozzle or the ladle nozzle of the second embodiment has the lower half portion 13b formed with the refractory excellent in erosion resistance against molten steel, it is possible to keep constant flow rate of molten steel flowing through the inner bore 14, even when the lower end of the molten steel pouring nozzle 13 is not provided with a publicly known control apparatus of molten steel flow rate such as a sliding nozzle.
Figure 9 is a schematic vertical sectional view illustrating a third embodiment of the molten steel pouring nozzle of the present invention. A molten steel pouring nozzle 13 of the third embodiment is also used as the tundish nozzle or the ladle nozzle. As shown in Figure 9, the molten steel pouring nozzle 13 as the tundish nozzle or the ladle nozzle, having along the axis thereof an inner bore 14 through which molten steel flows, comprises an upper part 13c of the inner surface portion of the molten steel pouring nozzle 13, which forms the upper part 14a of the inner bore 14, and the remaining portion 13d other than the above-mentioned upper part 13c, which forms the lower part 14b of the inner bore 14.The upper part 13c onto which aluminum oxide present in molten steel tends to deposit, is formed with a refractory having the chemical composition as described above, which produces the low-melting-point compound and mixture, whereas the remaining portion 13d other than the upper part 13c, onto which aluminum oxide relatively hardly deposits, is formed with any of the publicly known refractories excellent in erosion resistance against molten steel, having the chemical composition as described concerning the second embodiment of the molten steel pouring nozzle.
According to the molten steel pouring nozzle 13 as the tundish nozzle or the ladle nozzle of the third embodiment, as in the molten steel pouring nozzle of the second embodiment described with reference to Figure 8, aluminum oxide present in molten steel never deposits onto the upper part 13c of the inner surface portion of the molten steel pouring nozzle 13, which forms the upper part 14a of the inner bore 14, onto which the aluminum oxide tends to easily deposit.In addition, even when the upper part 14a of the inner bore 14 is expanded by the production of the low-melting-point compound and mixture, the lower part 14b of the inner bore 14 is relatively hardly expanded, since the remaining portion 13d other than the upper part 13c of the inner surface portion of the molten steel pouring nozzle 13 is formed with a refractory excellent in erosion resistance against molten steel, and it is thus possible to keep constant the flow rate of molten steel flowing through the inner bore 14. When the upper part 14a of the inner bore 14 has a funnel shape as shown in Figure 9, the lower portion of the uper part 14a of the inner bore 14 should have the same diameter as that of the lower part 14b of the inner bore 14.
Since the molten steel pouring nozzle 13 as the tundish nozzle or the ladle nozzle of the third embodiment has the remaining portion 13d other than the upper part 13c of the inner surface portion formed with the refractory excellent in erosion resistance against molten steel, it is possible to keep constant the flow rate of molten steel flowing through the inner bore 14, even when the lower end of the molten steel pouring nozzle 13 is not provided with a publicly known control apparatus of molten steel flow rate such as a sliding nozzle. In addition, the molten steel pouring nozzle 13 of the third embodiment has an advantage that, even when part of the junction between the upper part 13c of the inner surface portion and the remaining portion 13d other than the upper part 13c is eroded by molten steel, the remaining portion 13d hardly falls off from the upper part 13c.
Figure 10 is a schematic vertical sectional view illustrating a fourth embodiment of the molten steel pouring nozzle of the present invention. A molten steel pouring nozzle 15 of the fourth embodiment is used as an immersion nozzle which is fitted to the lower end of a molten steel pouring nozzle 3 as the tundish nozzle so as to project vertically and downwardly. It is needless to say that the molten steel pouring nozzle 3 as the tundish nozzle may be any one of the molten steel pouring nozzles 13 as the tundish nozzles of the first to the third embodiments described above. As shown in Figure 10, the molten steel pouring nozzle 15 as the immersion nozzle has along the axis thereof an inner bore 16 through which molten steel flows. The downstream end of the inner bore 16 branches off into a plurality of substantially horizontal discharge holes 17. The molten steel pouring nozzle 15 comprises an upper part 15a of the inner surface portion of the molten steel pouring nozzle 15, which forms the upper part 16a of the
inner bore 16, and the remaining portion 15c other than the above-mentioned upper part 15a, which forms the lower part of the inner bore 16. The upper part 15a onto which aluminum oxide present in
molten steel tends to deposit, is formed with a refractory having the chemical composition as described
above, which produces the low-melting-point compound and mixture, whereas the remaining portion 15c other than the upper part 15a, onto which aluminum oxide relatively hardly deposits, is formed with any of the publicly known refractories excellent in erosion resistance against molten steel, having the chemical composition as described concerning the second embodiment of the molten steel pouring nozzle.
According to the molten steel pouring nozzle 15 as the immersion nozzle of the fourth embodiment, aluminum oxide present in molten steel never deposits onto the upper part 15a of the inner surface portion of the molten steel pouring nozzle 15, which forms the upper part 16a of the inner bore 16, onto which the aluminum oxide tends to easily deposit.
Figure 11 is a schematic vertical sectional view illustrating a fifth embodiment of the molten steel pouring nozzle of the present invention. A molten steel pouring nozzle 15 of the fifth embodiment is also used as an immersion nozzle which is fitted to the lower end of a molten steel pouring nozzle 3 as the tundish nozzle so as to project vertically and downwardly. It is needless to say that the molten steel pouring nozzle 3 as the tundish nozzle may be one of the molten steel pouring nozzles 13 as the tundish nozzles of the first to the third embodiments described above. As shown in Figure 11, the molten steel pouring nozzle 15 as the immersion nozzle has along the axis thereof an inner bore 16 through which molten steel flows. The downstream end 16b of the inner bore 16 branches off into a plurality of substantially horizontal discharge holes 17.The molten steel pouring nozzle 15 comprises a lower part 15b of the inner surface portion of the molten steel pouring nozzle 15, which forms the downstream end 16b of the inner bore 16 including the plurality of discharge holes 17, and the remaining portion 15c other than the above-mentioned lower part 15b, which forms the upper part of the inner bore 16.The lower part 15b onto which aluminum oxide present in molten steel tends to deposit, is formed with a refractory having the chemical composition as described above, which produces the low-melting-point compound and mixture, whereas the remaining portion 15c other than the lower part 15b, onto which aluminum oxide relatively hardly deposits, is formed with any of the publicly known refractories excellent in erosion resistance against molten steel, having the chemical composition as described concerning the second embodiment of the molten steel pouring nozzle.
According to the molten steel pouring nozzle 15 as the immersion nozzle of the fifth embodiment, aluminum oxide present in molten steel never deposits onto the lower part 15b of the inner surface portion of the molten steel pouring nozzle 15, which forms the downstream end 16b of the inner bore 16 including the plurality of discharge holes 17, onto which the aluminum oxide tends to easily deposit.
Figure 12 is a schematic vertical sectional view illustrating a sixth embodiment of the molten steel pouring nozzle as a through-hole of the present invention, which is horizontally fitted in each of vertical weirs arranged in a tundish. A molten steel pouring nozzle 19 of the sixth embodiment is used as a through-hole which is horizontally provided in each of vertical weirs arranged in a tundish. As shown in
Figure 12, two vertical refractory weirs 18 are arranged at a prescribed distance therebetween in a tundish 1. The number of the weir 18 may be one or more. A plurality of molten steel pouring nozzles 19 as the through-holes, each having along the axis thereof an inner bore 20 through which molten steel passes, are horizontally secured in each of the two weirs 18.The entirety of the molten steel pouring nozzles 19 as the through-hole is formed with a refractory having the chemical composition as described above, which produces the low-melting-point compound and mixture.
According to the molten steel pouring nozzle 19 as the through-hole of the sixth embodiment, the flow of molten steel received from a ladle not shown into the tundish 1 is rectified while passing through the inner bores 20 of the plurality of molten steel pouring nozzles 19 as the through-holes secured in each of the two vertical weirs 18. In addition, aluminum oxide present in molten steel reacts with the refractory forming the molten steel pouring nozzles 19 as the through-holes to produce the low-melting-point compound and mixture which float up on the surface of molten steel. Therefore, it is possible to substantially remove aluminum oxide present in molten steel received in the tundish 1.Furthermore, since the inner bore 20 of each of the plurality of molten steel pouring nozzles 19 is never clogged up by the deposition of aluminum oxide, the flow of molten steel can be surely rectified. The inner bore 20 of the molten steel pouring nozzle 19 as the through-hole may be zigzag, apart from the linear shape as shown in Figure 12.
Now, the molten steel pouring nozzle of the present invention is described further in detail by means of an example.
Example
Three kinds of molten steel pouring nozzles as the tundish nozzle of the first embodiment shown in
Figure 7, formed with respective refractories having chemical compositions Nos. 5, 7 and 11 shwon in
Table 2 above and having an inner bore with a diameter of 16 mm were prepared. Then, for each of the thus prepared three kinds of molten steel pouring nozzles as the tundish nozzle, four nozzles were secured in the bottom wall of a respective tundish, and molten aluminum-killed steel having the chemical composition shown in the following Table 3 was continuously cast, for each of the three kinds of molten steel pouring nozzles, into four cast steel strands, each having a rectangular cross-section with a side of 140 mm.Continuous casting of 154 tons of the above-mentioned molten steel required a time of 120 minutes, and clogging of the inner bores of the molten steel pouring nozzles as the tundish nozzle was never caused by the deposition of aluminum oxide present in molten steel.
TABLE 3
(wt.%)
C Si P S Cu Soli! 0.12 0.15 0.015 0.013 0.28 0.012
For comparison purposes, on the other hand, four conventional molten metal pouring nozzles as the tundish nozzle formed with a zirconia refractory comprising 95 wt.% ZrO2 and having an inner bore with a diameter of 16 mm were secured in the bottom wall of a tundish, and molten aluminum-killed steel containing 0.012 wt.% Sol.Al was continuously cast into four cast steel strands, each having a rectangular cross-section with a side of 140 mm.After the lapse of about 10 minutes from the start of casting, deposition of aluminum oxide present in molten steel began to impair the flows of molten steel passing through the inner bores of the molten steel pouring nozzles as the tundish nozzle, and after the lapse of about 18 minutes from the start of casting, all the inner bores of the molten steel pouring nozzles were substantially clogged up, thus making it impossible to continue continuous casting any further.
According to the molten steel pouring nozzle as the tundish nozzle or the immersion nozzle of the present invention, as described above in detail, it is possible to prevent clogging up of the inner bore of the molten steel pouring nozzle as the tundish nozzle or the immersion nozzle caused by the deposition of aluminum oxide present in molten steel flowing through the inner bore, even when molten aluminumkilled steel having a high Sol.Al content is poured into a mold through the molten steel pouring nozzle having a small-diameter inner bore. It is thus possible to continuously cast molten aluminum-killed steel having such a high Sol.Al content into a cast steel strand of a small cross-section. Furthermore, according to the molten steel pouring nozzle as the through-hole of the present invention, which is horizontally fitted in the vertical weir arranged in the tundish, it is possible to remove aluminum oxide present in molten steel flowing through the inner bore of the molten steel pouring nozzle as the through-hole, thus providing industrially useful effect.
Claims (7)
1. A molten steel pouring nozzle having along the axis thereof an inner bore through which molten steel flows, characterized in that:
at least a part of said molten steel pouring nozzle is formed with a refractory consisting essentially of at least 30 wt.% calcium oxide and at least one of magnesium oxide and aluminum oxide; and
said refractory contains at least one of said magnesium oxide and said aluminum oxide so that the melting point of said refractory falls within the region of at least 2,2000C in the CaO-MgO-AI203 ternary phase diagram.
2. The molten steel pouring nozzle as claimed in Claim 1, characterized in that:
the entirety of said molten steel pouring nozzle is formed with said refractory.
3. The molten steel pouring nozzle as claimed in Claim 1, characterized in that:
said molten steel pouring nozzle comprises an upper half portion and a lower half portion, and said upper half portion is formed with said refractory.
4. The molten steel pouring nozzle as claimed in Claim 3, characterized in that:
said lower half portion of said molten steel pouring nozzle is formed with any one of zirconia refractory, silica refractory, zirconia-silica refractory, alumina-graphite refractory and alumina-silica refractory.
5. The molten steel pouring nozzle as claimed in Claim 1, characterized in that:
a part of the inner surface portion of said molten steel pouring nozzle, which forms said inner bore, is formed with said refractory.
6. The molten steel pouring nozzle as claimed in Claim 5, characterized in that:
the remaining portion other than said part of said inner surface portion of said molten steel pouring nozzle is formed with any one of zirconia refractory, silica refractory, zirconia-silica refractory, aluminagraphite refractory and alumina-silica refractory.
7. A molten steel pouring nozzle as claimed in Claim 1 and substantially as hereinbefore described with reference to the accompanying drawings.
Applications Claiming Priority (2)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP59271000A JPS61150759A (en) | 1984-12-24 | 1984-12-24 | Casting nozzle for steel making |
| JP60054175A JPS61215249A (en) | 1985-03-20 | 1985-03-20 | Molding composition for steeling |
Publications (3)
| Publication Number | Publication Date |
|---|---|
| GB8530807D0 GB8530807D0 (en) | 1986-01-22 |
| GB2170131A true GB2170131A (en) | 1986-07-30 |
| GB2170131B GB2170131B (en) | 1987-10-07 |
Family
ID=26394921
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| GB08530807A Expired GB2170131B (en) | 1984-12-24 | 1985-12-13 | Molten steel pouring nozzle |
Country Status (5)
| Country | Link |
|---|---|
| CA (1) | CA1263216A (en) |
| DE (1) | DE3545432A1 (en) |
| FR (1) | FR2575094B1 (en) |
| GB (1) | GB2170131B (en) |
| IT (1) | IT1186471B (en) |
Cited By (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US4870037A (en) * | 1987-09-23 | 1989-09-26 | Vesuvius Crucible Company | Prevention of Al2 O3 formation in pouring nozzles and the like |
| US5370370A (en) * | 1993-02-19 | 1994-12-06 | Vesuvius Crucible Company | Liner for submerged entry nozzle |
| US6475426B1 (en) | 2001-03-27 | 2002-11-05 | Vesuvius Crucible Company | Resin-bonded liner |
Citations (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| GB2123729A (en) * | 1982-07-05 | 1984-02-08 | Centro Speriment Metallurg | Casting of aluminium killed steel |
| EP0135482A1 (en) * | 1983-07-27 | 1985-03-27 | VESUVIUS ITALIA S.p.A. | Improved nozzles for casting aluminium-killed steels |
Family Cites Families (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US3540518A (en) * | 1967-08-29 | 1970-11-17 | Bethlehem Steel Corp | Method for continuously casting aluminum-killed steels |
| DE2804025A1 (en) * | 1977-02-02 | 1978-08-03 | Centre Rech Metallurgique | Continuous casting refractory nozzle mfr. - with addn. of finely divided refractory oxide to improve resistance to chemical attack |
-
1985
- 1985-12-12 CA CA000497534A patent/CA1263216A/en not_active Expired
- 1985-12-13 GB GB08530807A patent/GB2170131B/en not_active Expired
- 1985-12-19 IT IT23275/85A patent/IT1186471B/en active
- 1985-12-20 DE DE19853545432 patent/DE3545432A1/en active Granted
- 1985-12-24 FR FR858519139A patent/FR2575094B1/en not_active Expired - Fee Related
Patent Citations (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| GB2123729A (en) * | 1982-07-05 | 1984-02-08 | Centro Speriment Metallurg | Casting of aluminium killed steel |
| EP0135482A1 (en) * | 1983-07-27 | 1985-03-27 | VESUVIUS ITALIA S.p.A. | Improved nozzles for casting aluminium-killed steels |
Cited By (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US4870037A (en) * | 1987-09-23 | 1989-09-26 | Vesuvius Crucible Company | Prevention of Al2 O3 formation in pouring nozzles and the like |
| US5370370A (en) * | 1993-02-19 | 1994-12-06 | Vesuvius Crucible Company | Liner for submerged entry nozzle |
| US6475426B1 (en) | 2001-03-27 | 2002-11-05 | Vesuvius Crucible Company | Resin-bonded liner |
Also Published As
| Publication number | Publication date |
|---|---|
| IT1186471B (en) | 1987-11-26 |
| DE3545432A1 (en) | 1986-07-03 |
| DE3545432C2 (en) | 1988-09-22 |
| FR2575094B1 (en) | 1992-08-28 |
| CA1263216A (en) | 1989-11-28 |
| IT8523275A0 (en) | 1985-12-19 |
| FR2575094A1 (en) | 1986-06-27 |
| GB2170131B (en) | 1987-10-07 |
| GB8530807D0 (en) | 1986-01-22 |
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Legal Events
| Date | Code | Title | Description |
|---|---|---|---|
| PCNP | Patent ceased through non-payment of renewal fee |
Effective date: 19961213 |