JPH06238401A - Method for continuously casting different kinds of steels and connecting metal - Google Patents

Abstract

PURPOSE:To enable the continuous casting of two different kinds of steels having excellent partition and connection properties to the both kinds of steels by inserting a connecting metal into a mold, sealing between the inner surface of the mold and the plate-like member of the metal and pouring a second molten steel into the mold after solidifying a first molten steel. CONSTITUTION:After completing the pouring of the first molten metal 2, this drawing- down is stopped and an immersion nozzle 9 is pulled up, and successively, the connecting member 1 is dipped into the mold and acted as a chiller. By cooling of the mold, the solidification of the molten steel is progressed, and the bar-like member 1A in the connecting metal 1 and the first molten steel 2 are solidified and connected. Successively, the V-shaped seal material 8 composed of refractory, etc., is plugged into the gap between the inner surface of the mold 5 and the plate-like partition member 1B in the connecting metal 1 and thereafter, the immersion nozzle 9 is descended and the second molten steel 6 is poured, and the bar-like member 1C in the connecting metal 1 and the second molten steel 6 are solidified and connected. By this method, as the whole first molten steel can be poured in a tundish, the waste part of the first molten steel is eliminated and dipping-up work of the slag, etc., can be saved.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a continuous casting method for different steel types, and in particular, allows slag inflow into a mold, and allows for the next molten steel injection timing-free, excellent partitioning and connecting properties of both steel types. The present invention relates to a continuous casting method for steel types and a connected metal product.

[0002]

2. Description of the Related Art In continuous casting, it is of the utmost importance to perform casting with a good yield without interrupting the injection and without discarding the molten steel or the slab from the original purpose.

However, when continuously injecting molten steels of different steel types without any measures, the first molten steel and the second molten steel having different components are mixed in the tundish or in the mold, and thus the mixed slab is formed. In terms of the composition and composition, it cannot be applied to any steel type, and it is usually cut and discarded, and the length thereof reaches 4 to 5 m, which is a problem that the yield of molten steel cannot be left.

In the continuous casting of different steel types, various attempts have been proposed in the past to minimize the mixed portion generated.

For example, as shown in FIGS. 12 to 17, in order to eliminate the mixing of both molten steels in the tundish, all the molten steels in the tundish are poured into the mold 5, and the slag 4 flowing in at that time is poured. Then there is a method of removal.

FIG. 12 shows a state in which the first molten steel casting is completed,
FIG. 13 is a state in which the immersion nozzle 9 is then raised upward and the molten metal surface is lowered by a certain amount, FIG. 14 is a state in which the slag 4 is being pumped out by the slag pumping jig A, and FIG. 16 shows a state in which the sealing material is sprayed in the gap between the slab 3 and the mold 5, and FIG. 17 shows a state in which the immersion nozzle 9 is subsequently lowered to inject the second molten steel.

This method increases the work of pumping out the slag and deteriorates the workability. On the other hand, if the slag cannot be completely removed, there is a problem such as a breakout due to a decrease in the strength of the connecting portion.

As still another method, the first molten steel 2 and the slag 4 remaining in the tundish are all discharged and then the second molten steel is filled, or another tundish is replaced and then the second molten steel is replaced. There is a way to fill,
Both of them have a problem of yield reduction due to the abolition of molten steel.

A method is also conceivable in which the level of molten steel in the tundish or the weight of molten steel is measured to determine the completion of injection of the first molten steel into the mold, and the slag and molten steel are separated by blocking with a stopper or a sliding nozzle. At the end of injection, molten steel and slag are mixed and injected, and the accuracy of completion determination changes due to melting of refractory or adhesion of metal, etc., so slag and molten steel are completely separated and the slag flows into the mold. No, and first in the tundish
It is impossible to leave no molten steel.

As shown in FIG. 18, the tundish 1
Japanese Patent Laid-Open No. 01-224150 discloses a method for preventing the first molten steel slag 4 in No. 1 from flowing into the mold.

This is because when the pouring of the first molten steel 2 from the ladle is completed and the level of the first molten steel in the tundish 11 is lowered to a specific position, the spherical obstruction body 10 made of refractory is placed on the upper nozzle 9. It is a simple method of preventing slag outflow by throwing it in the upper part and closing the upper nozzle as the molten steel level decreases.

However, in this case, the spherical obstruction body 10 is not always stopped on the upper nozzle 9, and the upper nozzle 9 can be completely obstructed by melting damage or the like of the upper nozzle 9 and the spherical obstruction body 10. There is a risk of slag flowing into the mold.

Further, as shown in FIG. 19, a method for preventing the mixing of the first molten steel and the second molten steel of different steel types in the mold is shown in Japanese Examined Patent Publication No. 57-49308.

This is because once the injection of the first molten steel 2 into the mold 5 is temporarily stopped, the lower broad box-shaped cooling body 12 having a guide member is allowed to settle in the unsolidified portion of the first molten steel, and It is locked to the upper end of the solidified shell 3 of molten steel.

Next, a small iron piece 13 is put into the outer periphery of the box-shaped cooling body 12 to solidify the surface layer portion of the first molten steel, and the second molten steel 6 of different steel type is provided on the solidified layer of the first molten steel and in the box-shaped cooling body. However, when the slag in the tundish flows into the mold 5, the connection strength is insufficient.

Further, in each of the above methods, if a predetermined time or more is waited before starting the injection of the second molten steel, shrinkage of the slab or solidification of slag occurs, and there is a risk of breakout from the seam when the slab is pulled out. .

[0017]

As described above, according to the conventional method for continuous casting of different steel types, when there is slag in the mold, or when it is necessary to wait for a certain period of time before starting the injection of the second molten steel, Both of them are lacking in certainty and workability, and the length of the mixed portion of the first molten steel and the second molten steel has not been satisfactory yet.

The present invention has been made in view of the above,
The purpose is to inject all into the mold without leaving the first molten steel in the tundish at the end of casting with the first molten steel, in which case a part of the slag in the tundish flows into the mold. Also, even if it takes a certain amount of time to inject the second molten steel, the reliability of the joint portion between both steel types is high, so that casting can be continued without interruption, and the mixed portion of both steel types is also possible. It is an object of the present invention to provide a continuous casting method for dissimilar steel types, which is extremely short, has high reliability of the cast piece connection portion and is excellent in workability.

[0019]

SUMMARY OF THE INVENTION The present invention for solving the above-mentioned problems is a first casting method for a continuous casting method for different steel types.
In the continuous casting method of different steel types in which the second molten steel of different steel types is continuously injected after the completion of the molten steel injection, the step of injecting all the first molten steel in the tundish into the mold and stopping the withdrawal of the slab, A metal article composed of a plate-shaped member having a cross section substantially equal to the mold cross section and rod-shaped members standing up and down of the member is inserted into the mold, and the lower rod-shaped member of the metal is not solidified with the first molten steel in the mold. In the mold, solidifying the first molten steel in the mold, inserting a sealing material into the gap between the plate-shaped member of the metal object and the inner surface of the mold, and adding a different kind of steel on the metal object. 2 the step of pouring molten steel,
And a step of starting withdrawal of a slab after solidifying the second molten steel around the metal object. A continuous casting method for different steel types, comprising: A metal article for connecting the first molten steel and the subsequent second molten steel therein, which is characterized in that it comprises a plate-shaped member having a cross section substantially equal to the mold cross section and rod-shaped members standing above and below the member. It is a connecting metal for continuous casting of steel types.

Embodiments of the present invention will be described with reference to the accompanying drawings. FIG. 1 is a vertical cross-sectional view showing a method for connecting slabs according to an embodiment of the present invention, in which a connecting metal object connects a plate-shaped partition member 1B having a cross section substantially equal to the cross section of a mold and slabs provided above and below the partition member. It is formed from rod-shaped members 1A and 1C.

In this example, the section of the partition member is set so that the gap between the partition member and the mold is about 3 mm, and the thickness is at least 20 mm or more so as not to be melted by the second molten steel,
Usually, the one formed by cutting an iron plate having a thickness of about 50 mm is desirable.

The length of the rod-shaped member was set to about 300 mm at the lower part and about 200 mm at the upper part according to the solidification condition of the slab.

This connecting metal is provided in the mold so as to provide a space in the first molten steel below the partition member 1B for holding the slag which has partially flowed in from the tundish, and soaking the lower rod member 1A partially. And act as a chill, while cooling the mold solidifies the molten steel.
It is integrated with the molten steel slab 3.

Subsequently, in the gap between the inner surface of the mold and the block, a molten steel sealing material 8 which is usually used between the dummy bar and the inner surface of the mold.
Then, the second molten steel is injected from the immersion nozzle 9, and the upper rod-shaped member 1C is integrated with the second molten steel slab 7 as the molten steel solidifies.

The rod-shaped member 1A of the connecting hardware 1 according to the present invention,
The shape of 1C is not limited to that shown in FIG.
0, the cross-section as shown in FIG. 11 may be used, and the cross-sectional area in the direction perpendicular to the slab withdrawal direction should be at least one-third or more of the slab cross-section, usually one-half, and the length should be inflow slag. It is set by the amount and the binding force with molten steel.

2 to 6 are schematic views showing a working method according to one embodiment of the present invention. FIG. 2 is a state in which casting of the first molten steel is completed, and FIG.
Is a state in which the immersion nozzle 9 is then raised upward and the molten metal surface is lowered by a certain amount, and FIG. 4 is a state in which the slab-connecting metal fitting 1 of the first embodiment of the present invention is then immersed in the second molten steel, FIG.
Is the state in which the first molten steel is solidified and combined with the connecting metal piece 1, and the sealing material 8 for sealing the gap between the mold 5 and the plate-shaped metal piece of the connecting metal piece 1 is inserted. Then, the second molten steel 6 is injected, and the second molten steel 6
Shows a state in which the solidified and is bonded to the connecting metal article 1.

[0027]

In the present invention, the first molten steel in the tundish is poured almost entirely into the mold so that the first molten steel remains in the tundish and is not mixed with the second molten steel.

Further, the lower rod-shaped member of the connecting metal article is immersed in the unsolidified portion of the first molten steel in the mold so as to provide a space under the partition metal article for sufficiently holding the slag which has partially flowed from the tundish. By further sealing the gap between the partition of the connecting member and the inner surface of the mold, it is not necessary to pump out the slag in the mold at the end of the injection of the first molten steel,
It is possible to connect slabs with slag.

In addition, when it is necessary to inject the second molten steel for a certain period of time, the second molten steel may be injected even when the slag is solidified and the slab of the first molten steel contracts to form a gap with the mold. By solidifying and joining the rod-shaped metal on the upper part of the connecting member and the second molten steel, it is possible to connect the cast pieces with high reliability without stopping the continuous casting.

[0030]

Embodiments of the present invention will be described with reference to the accompanying drawings. The present invention was carried out at the time of producing a cast piece having a cast piece width of 170 mm and a cast piece thickness of 160 mm in a curved continuous casting apparatus.

First, after the completion of the injection with the first molten steel 2, the withdrawal is stopped, and the immersion nozzle 9 is pulled up,
Next, the slab connecting member 1 having the dimensions as shown in FIG. 8 is immersed in the state as shown in FIG. 1 to act as a chill, while cooling of the mold progresses the solidification of the molten steel, and the rod-shaped member 1A of the connecting metal 1 And the first molten steel 2 were solidified and connected.

At this time, the slag 4 floating on the surface of the first molten steel 2 is about 30 mm, and the slag 4 and the lower surface of the plate-shaped partition member 1B
The distance between the molten steel surfaces was set to about 50 mm.

Next, a V-shaped sealing material 8 made of a refractory material or the like, which is normally filled in the space between the dummy bar and the inner surface of the mold, is filled in a space of about 3 mm between the inner surface of the mold 5 and the plate-shaped partition member 1B of the metal fitting 1. , Then lower the immersion nozzle 9,
Injecting the second molten steel 6 into the rod-shaped metal 1C of the connecting member 1 and the second
The molten steel 6 was solidified and connected.

Casting was completed without cutting the slab connecting portion midway. The result of the investigation by cutting the formed slab was as shown in FIG. 7, and no mixing of both steel types was observed.

At this time, the length of the cut-off portion as good steel is 300 mm in the cast portion 15 of the first molten steel and 250 mm in the cast portion 16 of the second molten steel, which is 550 mm in total, and the molten steel yield is extremely good. It was confirmed.

[0036]

As described above, according to the present invention, in the continuous casting of different steel types, the first molten steel in the tundish can be entirely poured into the mold, so that the first molten steel can be completely discarded. Since the slabs can be connected with the slag in the mold, pumping work of slag can be omitted.

Further, when it is necessary to wait for a certain period of time before starting the injection of the second molten steel, there is no risk of breakout even if slag solidification or slab contraction occurs. Can be suppressed. Further, since the molten steel is completely sealed by the sealing material in the gap between the inner surface of the mold and the metal fitting, there is no mixing of the molten steel and therefore the yield is dramatically improved.

[Brief description of drawings]

FIG. 1 is an explanatory view showing an embodiment of a connection part in a mold during continuous casting of different steel types according to the present invention.

FIG. 2 is an explanatory diagram showing an embodiment of a work method of the present invention.

FIG. 3 is an explanatory view showing an embodiment of a working method of the present invention.

FIG. 4 is an explanatory view showing an embodiment of a working method of the present invention.

FIG. 5 is an explanatory diagram showing an embodiment of a work method of the present invention.

FIG. 6 is an explanatory view showing an embodiment of a working method of the present invention.

FIG. 7 is an explanatory view showing an example of a connection state between cast pieces of different steel types according to the present invention.

FIG. 8 is an explanatory view showing the dimensions of the connecting metal article of the embodiment of the present invention.

FIG. 9 is an explanatory view showing another example of the connected metal article of the present invention.

FIG. 10 is an explanatory view showing another example of the connected metal article of the present invention.

FIG. 11 is an explanatory view showing another example of the connecting metal article of the present invention.

FIG. 12 is an explanatory view showing a conventional working method during continuous casting of different steel types.

FIG. 13 is an explanatory view showing a work method in the conventional continuous casting of different steel types.

FIG. 14 is an explanatory view showing a conventional working method during continuous casting of different steel types.

FIG. 15 is an explanatory view showing a conventional working method during continuous casting of different steel types.

FIG. 16 is an explanatory view showing a work method in the conventional continuous casting of different steel types.

FIG. 17 is an explanatory view showing a conventional working method during continuous casting of different steel types.

FIG. 18 is an explanatory view showing a conventional slag outflow prevention method in a tundish.

FIG. 19 is an explanatory view showing a conventional method for connecting different steel types.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Connection member 2 1st molten steel unsolidified part 3 1st molten steel solidified part 4 1st molten steel slag 5 Mold 6 2nd molten steel unsolidified part 7 2nd molten steel solidified part 8 Molten steel sealing material 9 Immersion nozzle 10 Spherical obstruction body (slag ball ) 11 tundish 12 box-shaped cooling body A slag pumping jig B sealing material spraying jig 13 small iron piece 14 upper nozzle 15 first cast piece 16 second cast piece

Claims (2)

[Claims] 1. A continuous casting method for different steel grades, wherein after continuously injecting the first molten steel into the mold, the second molten steel of different steel type is continuously poured, the first molten steel in the tundish is entirely poured into the mold for casting. Stopping the pulling out of the piece, and inserting a metal article consisting of a plate-shaped member having a cross section substantially equal to the mold cross section and rod-shaped members standing up and down of the member into the mold,
Immersing the lower rod-shaped member of the metal object in the unsolidified portion of the first molten steel in the mold, solidifying the first molten steel in the mold, and sealing in the gap between the plate member of the metal object and the inner surface of the mold. A step of inserting a material, a step of injecting a second molten steel of a different steel type onto the metal piece, and a step of solidifying the second molten steel around the metal piece and then starting withdrawal of a slab. A continuous casting method for different steel types. 2. In a continuous casting of different steel types,
A continuous metal casting for connecting different molten steel to a second molten steel, which comprises a plate-shaped member having a cross section substantially equal to the mold cross section and rod-shaped members erected above and below the member. For connecting hardware.