JPS6289566A - Refractories for flow of molten metal - Google Patents

Abstract

PURPOSE:To prevent the clogging in a flow passage for a molten metal and the local wear thereof by forming rugged parts to the surface of the flow passage for the molten metal. CONSTITUTION:Many semi-spherical recesses 13 are provided to the inside surface of the flow passage 12 formed in a ladle nozzle 11 over the entire part thereof to form the rugged parts thereto. An openable and closable sliding nozzle 41 which is used with a tundish for continuous casting, etc., is formed with the flow passage 44 by a stationary plate 42 and a movable plate 42. The rugged parts are provided to the surface of the flow passage of the movable plate 43 by providing many semi-spherical projections 45 to said surface in this case. The rugged parts on the surface of the flow passage form turbulence in the stage when the molten metal flows in the passages and therefore, the sticking and deposition of the non-metallic inclusions in the molten metal are suppressed and the clogging in the flow passage is prevented. The local wear of the flow passage is prevented from the decreased vortex energy.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a molten metal flow refractory suitable for use in a molten metal flow rate adjustment section in a molten metal supply section to a casting apparatus.

[Prior Art] Conventionally, a ladle nozzle 1 shown in FIG. 6th
A device that maintains the supply flow rate constant, such as the submerged nozzle 2 shown in the figure, or a tundish that opens and closes the runner inlet shown in Fig. 7) -/Continuous as shown in Part 3 and Fig. 8 There are devices that suppress the flow rate, such as a sliding nozzle 4 of a casting device.

In order to stably perform molten metal casting using a casting apparatus equipped with this type of refractory, it is required that the molten metal flow path of the refractory maintain a predetermined shape. However, in reality, for example, when aluminum guild steel is used, nonmetallic inclusions in the steel (nonmetallic inclusions generated by deoxidation of alumina, etc.) are sintered at the interface between the refractory and molten steel. The particles adhere and accumulate on the surface of the flow path, gradually changing the flow path adjustment cross-sectional area, and progressing further, resulting in a blocked state. In addition, for example, in a structure such as the sliding nozzle 4 in a continuous steel casting apparatus, the portion receiving the molten metal drift caused by opening and closing changes locally. Due to these causes, the surface shape of the flow passage of the refractory for flow rate adjustment is constantly changing, and stable multiple casting operations cannot currently be performed.

From this point of view, various countermeasures have been proposed in the past. For example, to prevent passage blockage during casting, as shown in Figs. A gas introduction slit 5 is formed inside, and this slit 5
Inert gas is blown into the flow passage through the pipe to create a turbulent flow of the molten metal inside the pipe. Alternatively, an easily meltable material containing a large amount of silica is applied to the refractory, and
It has also been proposed to use materials that are difficult to wet with molten steel (hereinafter referred to as hard-to-wet materials), such as zirconium boride and poron nitride, to refractories.

Furthermore, as a measure against localized wear and tear, a highly corrosion-resistant material such as high alumina is applied to the refractories of the tundish stopper 3 and the sliding nozzle 4, or this material is miniaturized and formed into a ring shape, so that the refractories of the tundish stopper 3 and the sliding nozzle 4 are made of a highly corrosion-resistant material. There are also proposals to apply the same.

[Problems to be Solved by the Invention] However, all of the conventional solutions have the following problems. In other words, the method of introducing an inert gas has the drawback that the inert gas is trapped in the molten steel and solidified, causing surface defects during rolling. The damaged material becomes trapped in the molten steel and becomes a new source of non-metallic inclusions, deteriorating the quality of the steel. Furthermore, even when a hardly wettable material is applied to a refractory material, the cost is relatively high compared to the effect of preventing passage blockage, and there is a problem that it is difficult to put it into practical use. On the other hand, when a highly corrosion-resistant material is used as a refractory material as a measure against localized wear, the thermal expansion coefficient increases due to its chemical composition, resulting in poor spalling resistance and the inconvenience that cracks are more likely to occur at the start of casting. Although spalling resistance is improved if the ring shape is formed, there is a disadvantage that the problem of metal insertion occurs on the ring joint insertion surface.

The present invention has been made by focusing on the above-mentioned conventional problems, and solves the problem of blockage of the flow path of molten metal and local wear and tear by providing a simple shape without introducing an inert gas or changing or adjusting the refractory material. The purpose of the present invention is to provide a molten metal flow refractory which can solve the problems by simply changing the above problems.

[Means and effects for solving the problems] In order to achieve the above object, the molten metal flow refractory according to the present invention has an uneven portion formed on the surface of the molten metal flow path.

According to this configuration, first, the uneven portions provided on the flow path surface of the upper and lower ladle nozzles, immersion nozzles, sliding nozzles, or tundish stoppers, which constitute the flow path in contact with the molten metal, create turbulence in the flowing molten metal. stirring and mixing in the flow path. Therefore, it is possible to effectively suppress precipitation and adhesion of non-metallic inclusions at the interface and solidification blockage due to stagnation of molten metal, thereby preventing a decrease in productivity and deterioration of product quality.

Also, locations where sudden changes in molten metal flow occur.

For example, by providing an uneven part on the throttle injection part or the end face of the stopper of a sliding nozzle, the energy of the vortex generated by throttle injection or sudden changes in the flow direction is reduced by the turbulent flow generation effect of the uneven part, and the sliding nozzle due to the vortex is reduced. This prevents local wear and tear on the end face of the plate and the end face of the stopper head.

Note that the unevenness formed on the surface of the flow path may vary depending on the shape of the nozzle, etc., or operating conditions such as the adhesion and accumulation of inclusions.
It is only necessary to determine the size and number of the refractories, but in the case of refractories used in general molten metal flow regulating devices, the irregularities have a circular arc cross section with a radius of R = 2 to 9 mm, and the arrangement is necessary. It is preferable that the particles are arranged approximately uniformly at the location, and
The ratio of the uneven portion to the area of the metal flow path inside the refractory is 7 to 40%.
The degree is suitable in that it gives a turbulent flow effect.゛Also,
The unevenness may be formed directly on the surface of the flow path, but if necessary, a higher effect can be obtained by applying a combination of a material that is difficult to wet, such as poron nitride, and further improving the adhesion and accumulation of inclusions. It is clear that

[Embodiments of the invention] (Example 1) In casting aluminum guild steel, Figs. 1 (A) and (B)
The molten metal was supplied using a nozzle 11 on the ladle as shown in FIG. This nozzle 11 has a concavo-convex portion formed by providing a large number of hemispherical concave portions 13 over the entire inner surface of a flow path 12 formed inside. A general refractory material (for example, brick) was used as the refractory material, and a porous material for gas injection was applied to the nozzle 1 shown in FIG. 5 used for comparison.

During casting, when the molten metal was flowed without blowing gas using the nozzle l shown in FIG. 5, the nozzle became clogged in the middle of the flow path, and it took twice as long as the casting plan. As a countermeasure to this problem, gas injection was carried out, but it was necessary to inject a large amount of inert gas to overcome the static pressure of the molten steel, resulting in a large temperature drop in the molten steel and oxidation of the bare molten metal surface.

On the other hand, when the example nozzle IT shown in Fig. 1 was used, the nozzle was not clogged at all even though no gas was blown, and the casting was completed within the scheduled casting time, confirming its effectiveness. .

(Example 2) In continuous casting of aluminum killed steel, Fig. 2 (A), (
The immersion nozzle 21 shown in B) was used.

This nozzle 21 is provided with a main flow passage 22 and a discharge flow passage 23, and a large number of hemispherical recesses 24 and hemispherical protrusions 25 are alternately formed on the inner surface of the flow passage. On the other hand, as a comparative example, an inert gas blowing operation was performed using the immersion nozzle 2 having the same shape as shown in FIG.

In the comparative example, even though inert gas was blown at 5 JL/min, the nozzle was clogged from the main stream passage 22 at the bottom of the nozzle to the discharge flow passage 23, and the casting plan was for 5 consecutive castings, but the nozzle was clogged during 3 consecutive castings. We had no choice but to stop casting. On the other hand, in this example, the planned five continuous castings were completed.

Further, when the refractory brick of the nozzle 21 was observed after the completion of casting, almost no nonmetallic inclusions or solidified iron were observed on the inner wall surface, confirming the effect. Furthermore, the surface defects caused by gas traps that occurred when the general gas blowing immersion nozzle 2 was used were not observed at all in the cast product using the nozzle 21 of this embodiment, and the amount of surface scarf was reduced to about 1/3. The yield was significantly improved.

(Example 3) In continuous casting of low alumina-high manganese steel, a tundish stopper 31 shown in FIGS. 3(A) and 3(B) was used. 3(C) on the head end surface of this stopper 31.
As shown in the figure, a large number of hemispherical concave portions 32 and hemispherical convex portions 33 are alternately provided to form an uneven portion. As a comparative example, the seventh
A conventional stopper 3 without an uneven surface as shown in the figure was used.

When using the comparative example of Sto, Pa 3, the tip part suffered melting damage and a failure to stop the hot water occurred.
We had no choice but to stop midway through three consecutive castings. On the other hand, in this example, the planned four continuous castings were completed. When the stopper 31 was observed after the casting was completed, almost no melting damage was observed, confirming its effectiveness.

(Example 4) In the continuous casting of low carbon steel, the small knob 41 shown in FIG. The channel 44 is opened and closed by throttling, and an uneven portion is formed by providing a large number of hemispherical convex portions 45 on the surface of the flow path of the movable plate 43.

In the comparative example, the sliding nozzle 4 shown in FIG. 8 without unevenness was used.

When Nozzle 4 of Comparative Example was used, the inner surface of the flow passage of the movable plate, which is the plate on the opposite side of the injection flow side, was damaged by the vortex generated by the flow rate control, and the operation was stopped midway through 5 continuous castings compared to the planned 8 continuous castings. However, in this example, Plan 8i! We were able to stably complete casting of ly& and confirm its effectiveness.

[Effects of the Invention] As explained above, according to the present invention, by forming a large number of uneven parts on the surface of the flow path of molten metal, non-metallic inclusions in the molten metal are caused by the turbulent flow generated by the uneven parts. This prevents passage clogging by suppressing the adhesion and accumulation of water, and also prevents local wear and tear by reducing the vortex energy in the flow control section, so simple shape improvements can achieve high spall resistance without compromising spall resistance. Effects can be obtained.

[Brief explanation of drawings]

Figures 1 (A) and (B) are longitudinal and transverse cross-sectional views of the ladle nozzle of the example, Fig. 2 (A) and (B) are longitudinal and transverse cross-sectional views of the same immersion nozzle, and Fig. 3 (A) and (B). ), (+,) are longitudinal and transverse cross-sectional views and enlarged cross-sectional views along the line C-C of the same tanditshu stopper, and the fourth
Figures (A) and CB) are longitudinal and transverse cross-sectional views of the same sliding nozzle. Figures 5 (A) and (B) are vertical and horizontal cross-sectional views of a conventional ladle nozzle, Figures 6 (A) and (B) are vertical and horizontal cross-sectional views of the same immersion nozzle,
FIGS. 7(A) and (B) are longitudinal and transverse sectional views of the tundish stopper, and FIGS. 8(A) and (B) are longitudinal and transverse sectional views of the sliding nozzle. 11... Ladle top nozzle, 21... Immersion nozzle. 31...Tandish stopper, 41...Sliding nozzle, 12.22.2, 3, 44...Flow path, 13.24.
32... Hemispherical concave portion, 25.33.45... Hemispherical convex portion. Agent Patent Attorney Shigeno
Figure 5 Figure 7 Figure 6 Figure 8

Claims (3)

[Claims] (1) A molten metal flow refractory characterized by having an uneven portion formed on the surface of a flow path for molten metal. (2) The molten metal flow refractory according to claim 1, wherein the flow path for the molten metal is a constant flow nozzle path. (3) The molten metal flow refractory according to claim 1, wherein the flow path for the molten metal is a throttled flow path that can be opened and closed.