JP5147381B2 - Continuous casting method of different steel types - Google Patents

Description

  The present invention relates to a continuous casting method of steel, and more particularly to a continuous casting method in the case where the precharge and postcharge steel types in a mold are different steel types.

  In continuous casting of steel, continuous casting is generally performed in which molten steel is sequentially supplied from a plurality of ladles to the same mold in order to improve productivity. The molten steel from the preceding ladle is called the front ladle molten steel (hereinafter referred to as “pre-charged molten steel”), and the molten steel from the subsequent ladle is referred to as the rear ladle molten steel (hereinafter referred to as “post-charged molten steel”). A continuous casting of a plurality of steel types in which the steel type of the molten steel in the post-charge is different from that of the different steel types.

  As prior arts of continuous casting of different steel types, there are the following patent documents 1 to 5. Patent Documents 2 to 5 are methods in which continuous casting is performed continuously without losing the original continuous casting function as much as possible. This is intended to reduce the mixing of components at the joint between the precharged molten steel and the postcharged molten steel, but the effect is not always sufficient.

  Patent Document 1 aims to prevent mixing of components in the joint portion between the precharged molten steel and the postcharged molten steel, but is not sufficient as a cleanliness measure for the bottom steel material, which is an initial casting material. The molten steel immediately after being poured into the mold by the post-charge is contaminated by residues after the casting of the pre-charged molten steel, air oxidation if the seal in the mold is insufficient or cannot be carried out in a process, Alternatively, if the tundish is used for the first time, it becomes a contaminated molten steel in which a very large number of non-metallic inclusions are suspended due to various factors such as contamination by refractory fallout in the tundish. ing. Therefore, it is necessary to improve the cleanliness of the subsequent molten steel by measures such as improving the cleanliness of the molten steel as much as possible and solidifying it at an early stage of casting.

  That is, it is a partition metal that is attached to the lower part of the molten steel vessel and is used for continuous casting of different steel types. The partition plate may be provided with a partition plate member for mold adjustment according to the mold width, and a mold guide is provided. Alternatively, a method has been proposed in which the partition metal is locked to a jig attached to the molten steel container, and then the molten steel container is lowered and inserted into the mold (for example, see Patent Document 2). However, in the method of pushing the partition metal into the molten steel in the mold, there is a problem that a component mixing zone occurs.

  In addition, a jig is attached to the lower part of the molten steel container, a mounting rod is coupled to the inner side of the partition plate, and the tip is rotatably locked by the jig, and the partition plate is moved into the mold by the operation of the molten steel container. Has been proposed (see, for example, Patent Document 3). However, this method has a problem that in the embodiment, the partition plate is inserted in a divided manner, the partition wall action of the partition plate is insufficient near the lower part of the immersion nozzle, and the component mixing area in the slab becomes long.

  Furthermore, a method has been proposed in which a molten steel stirring force by a moving magnetic field is applied to the molten steel staying portion of the front pan steel type at the upper part of the mold, and a braking force by a static magnetic field is applied to a corresponding portion of the molten steel discharge flow from the immersion nozzle ( For example, see Patent Document 4.) However, this method has a problem that a component mixing region occurs because only the magnetic field is used for switching the steel type.

  Furthermore, a solid steel layer separating the different steel types directly under the nozzle is formed by introducing particulate steel coolant from above the meniscus in the mold and dispersing and dissolving the particles by centrifugal force by electromagnetic stirring in the mold. A forming method has been proposed (for example, see Patent Document 5). However, since the front ladle molten steel remains on the solidified layer, there is a problem that a component mixing zone occurs due to the injection of the rear ladle molten steel.

  On the other hand, the drawing of the preceding slab in the mold is temporarily stopped, and thereafter, the connection metal fitting for connecting the slab and the succeeding slab to the unsolidified portion at the rear end of the preceding slab in the mold and the both slabs. A sequence block having a shielding plate for shielding component mixing is inserted, and a molten steel of a different steel type is injected into the sequence block located at the rear end of the preceding slab in the mold, and the slab is drawn out. A method has been proposed in which continuous casting is performed by continuously performing the preceding slab and the subsequent slab through a sequence block (for example, see Patent Document 1). This method can be evaluated in terms of preventing mixing of different components, but is not sufficient as a measure for cleanliness of post-charge molten steel. If the deposits on the inner wall of the mold, that is, the slag film and the slag bear are not removed, a molten steel contamination source remains in addition to the molten steel connecting portion of the front and rear charges. Even if the pre-charged molten steel residue can be shut out by the partition plate, it is not a countermeasure against inclusions in the air oxidation system and tundish refractory system, so the effect of improving the cleanliness of the bottom steel material, which is the steel material in the early casting stage, is not enough. In addition, depending on the size of the partition plate, there is a possibility that it cannot be smoothly inserted into the mold.

  Continuous casting of different steel types, especially separation of a pre-charged partition plate or shielding plate at the rear end of the pre-charged molten steel with the intention of preventing mixing of the components of the pre-charged molten steel and the post-charged molten steel as in Patent Document 1. When paying attention to the problem of cleanliness in the continuous casting method in which a material is installed and molten steel for post-charging is injected from above, it is necessary to pay attention to the following points.

  In the continuous casting of the above different steel types, using a connecting member having a separating material such as a partition plate and a shielding plate, in the method of installing the separating material at the rear end of the molten steel of the pre-charge, as a partition plate and a shielding plate, A relatively thin steel plate or an inexpensive steel plate can be used, but as a result of considering the workability of insertion and installation in the mold, the plate size of the partition plate and the shielding plate is often smaller than the mold size. Therefore, even if such a plate is statically installed on the surface of the molten steel, if there is some indentation, the molten steel or molten powder layer may flow into the plate. This is particularly likely when the steel sheet is bent. If there is residue resulting from the flow of molten steel in the precharge or molten powder layer, it will cause contamination of the molten steel when pouring the molten steel in the postcharge, and clean the molten steel in the unsteady part immediately after the start of casting the molten steel in the postcharge. Remarkably deteriorates sex. Powder residue between the outer periphery of the partition plate and the inner wall of the mold is also a source of molten steel contamination. In addition, the slag film and, in some cases, deposits including slag bear remain on the inner wall of the mold where the molten steel for the post-charge is filled, or the deposits are peeled off or dropped off, or the deposits are dropped off. If the residue is on the partition plate or the shielding plate or between the outer periphery of the partition plate and the inner wall of the mold, this also becomes a contamination source of the molten steel, which significantly deteriorates the cleanability of the molten steel in the unsteady part at the initial stage of casting of the post-charge. Furthermore, the molten steel immediately after the start of casting is the worst part of cleanliness in terms of inclusions in the air oxidation system and the tundish refractory system.

  For the reasons described above, the molten steel at the initial stage of the post-charge casting is contaminated molten steel in which a large number of non-metallic inclusions are suspended. The range of the stationary part is also long. However, the effect of reducing the range of the unsteady portion made of contaminated molten steel at the initial stage of post-charging cannot be obtained only with a connecting member having a separating material such as a partition plate or a shielding plate.

JP-A-64-83346 JP 2004-174515 A JP-A-63-192542 Japanese Patent Laid-Open No. 11-342456 Japanese Unexamined Patent Publication No. 7-32098

  A method of using a jig with a partition plate and a shielding plate in a mold by continuous casting of different steel types is evaluated from the viewpoint that the effect of preventing mixing of components between the pre-charge and the post-charge is high. However, in the situation where inclusions are generated due to contamination by residues after completion of casting of molten steel in the precharge, air oxidation, or refractories in the tundish, non-immediately after the start of casting in the postcharge. The cleanliness of the stationary part is significantly deteriorated.

  Therefore, the problem to be solved by the present invention is to solve the problem of deterioration of the cleanliness of the molten steel in the post-charge, particularly in the initial casting portion, in the continuous casting of different steel types. In the absence of mixing, a connecting member having an appropriate partition plate and a cooling member made of a cold material are used to reduce contamination of the molten steel at the initial stage of casting of the post-charge by the residue of the pre-charge as much as possible. The molten steel part contaminated with residues and the like is solidified at an early stage of casting to prevent deterioration of the cleanliness of the molten steel in the initial casting part. Furthermore, by performing electromagnetic stirring, the effect of uniform cooling of the slab is obtained, the drift of the contaminated molten steel is suppressed, and the contamination range is prevented from expanding to the rear of the charge. And, by these comprehensive effects, to provide a method for shortening the unsteady part length defined in the range of contaminated molten steel at the initial casting stage and improving the cleanliness of the bottom steel material as the initial casting initial material It is.

  The present invention is a method in continuous casting of different steel types of steel, in which a connecting member is installed at a location between the pre-charge and the post-charge, and a cold material is installed before the molten steel of the post-charge is injected. This is a continuous casting method in which work is performed, after-charge is started to be injected into the mold, and electromagnetic stirring is started from a predetermined timing. The method is as follows: (1) After a predetermined amount of cooling material is installed following installation of the connecting member, casting of a post charge is started, and (2) after injecting post charge, a predetermined strength is obtained from a predetermined timing. It consists of the method of performing electromagnetic stirring.

  Further, the present invention is a method in continuous casting of different steel types of steel, installing a connecting member at a location between the pre-charge and the post-charge, and installing a cold material before injecting the molten steel of the post-charge, This is a continuous casting method in which predetermined work is performed, post-charge is started to be injected into the mold, and electromagnetic stirring is started from a predetermined timing. The method includes (1) removing the slag film and residues in the mold, and (2) installing a connecting member having a partition plate of a predetermined size at the rear end of the pre-charge. After a predetermined amount of cold material is installed between the outer periphery and the inner wall of the mold, casting of a post-charge is started. (3) After the start of post-charge injection, electromagnetic stirring with a predetermined strength is performed from a predetermined timing. It consists of a method.

  These methods are different from the method of Japanese Patent Application No. 2006-261787 of the invention of the inventors' prior application in that electromagnetic stirring with a predetermined strength is carried out from a predetermined timing.

  That is, the means of the present invention for solving the problem is that, in the invention of claim 1, in the continuous casting of different steel types, after the connecting member is installed at the rear end of the precharged molten steel in the mold, the postcharged molten steel is provided. Before injecting the cold material, install the cold material, and start pouring the molten steel of the post-charge into the mold. By this injection, when the value obtained by dividing the injection amount of the molten steel of the post-charge into the mold by the slab cross-sectional area becomes a predetermined value, the magnetic stirring that gives the predetermined average flow velocity is applied to the molten steel of the post-charge. Thus, the continuous casting method of different steel types is characterized in that the length of the unsteady portion made of contaminated molten steel at the initial stage of post-charging is shortened.

  In the method of the means of claim 1, since the cold material is installed after the connecting member is installed and before the molten steel of the post-charge is injected, immediately after the start of casting that is contaminated by the residue of the pre-charge and the like. The molten steel part can be solidified early. Furthermore, by performing electromagnetic stirring with a predetermined strength from a predetermined timing after the start of the injection of the molten steel in the post-charge, the effect of cooling the slab uniformly is obtained, the drift of the contaminated molten steel is suppressed, and the slab end portion is not The length of the stationary part can be shortened. Further, the total effect of the use of cold material and electromagnetic stirring can reduce the range of the unsteady portion from the front end of the slab at the beginning of casting and prevent deterioration of the cleanliness of the subsequent slab.

  In the invention of claim 2, in the continuous casting of different steel types, after installing the connecting member having a partition plate narrower than the slab size at the rear end of the molten steel of the precharge in the mold, before injecting the molten steel of the postcharge The slag film remaining on the inner wall of the mold is removed by removing the residue on the partition plate of the connection member and between the outer periphery of the partition plate and the inner wall of the mold, and further on the partition plate of the connection member and the partition plate. A cold material is installed between the outer periphery and the inner wall of the mold, and the injection of the molten steel for the post-charge is started, and then the value obtained by dividing the injection amount of the molten steel for the post-charge by the slab cross-sectional area is a predetermined value. From this point, the length of the unsteady part consisting of contaminated molten steel in the initial stage of post-charging is shortened by applying electromagnetic stirring that gives a predetermined average flow velocity to the molten steel in the post-charge. Is the method.

  According to the method of the means of claim 2, it is possible to cope with the case where the mold is tapered by installing a connecting member having a partition plate narrower than the slab size. And, removing the slag film adhering to the inner wall of the mold, eliminating the fallen off, etc., removing the contamination source of the molten steel of the post-charge such as the residue on the partition plate and between the outer periphery of the partition plate and the inner wall of the mold, The contamination of the post-charge molten steel itself is reduced, and the extent of post-charge contamination can be prevented. The effect of the cold material is the same as in the case of the above-described claim 1, and the effect of electromagnetic stirring is also the same as that of the above-mentioned claim 1. The total of the above three effects can reduce the range of the unsteady portion from the front end of the slab in the initial casting portion, and can prevent the deterioration of the cleanliness of the subsequent molten steel.

In the invention of claim 3, the connecting member and the cooling material are made of iron or steel, and a value obtained by dividing the total mass by the cross-sectional area of the slab is 200 to 370 kg / m ^2. It is a continuous casting method of different steel types according to the means of item 1 or 2.

In the method of the means of claim 3, a predetermined cooling effect can be obtained by using iron or steel as the connecting member having the partition plate and the cooling material, and the total mass of the connecting member and the cooling material is cut off from the slab. By setting the value divided by the area to 200 to 370 kg / m ² , it is possible to solidify the molten steel part contaminated by the residue of the precharge at an early stage of casting and improve the cleanliness of the subsequent molten steel. When the value obtained by dividing the total mass of the connecting member and the cooling material by the cross-sectional area of the slab exceeds 370 kg / m ² , the effect exceeding the predetermined cooling effect is not obtained. Rather, the cold material becomes bulky, and it is necessary to strictly adjust the positional relationship with the immersion nozzle in the mold.

The invention according to claim 4 is characterized in that the electromagnetic stirring is started when the value obtained by dividing the amount of the post-charge molten steel injected into the mold by the slab cross-sectional area is in the range of 0 to 2700 kg / m ^2. It is the continuous casting method of the different steel types of the means of any one of Claims 1-3.

In the method according to the fourth aspect of the present invention, if the timing of starting electromagnetic stirring is delayed, uniform cooling of the slab is hindered and the influence of drift of contaminated molten steel occurs. The value obtained by dividing the injection amount by the cross-sectional area of the slab is in the range of 0 to 2700 kg / m ² . By the way, it is even more preferable that the value obtained by dividing the amount of injection into the mold by the start of the action of electromagnetic stirring divided by the cross-sectional area of the slab is in the range of 1200 to 2300 kg / m ² .

  The invention according to claim 5 is characterized in that the electromagnetic stirring gives a stirring flow rate of an average flow rate of 10 to 130 cm / sec to the post-charged molten steel, and the continuous casting of different steel types according to any one of claims 1 to 4 Is the method.

  In the method of the means of claim 5, the preferable average flow rate of the molten steel by electromagnetic stirring is set to 30 to 130 cm / sec. This electromagnetic stirring ensures the effect of uniform cooling of the slab. If the stirring intensity is too strong, there is a concern about secondary molten steel contamination due to the entrainment of the meniscus portion of the molten steel in the mold, so the upper limit of the average flow velocity is set to 130 cm / sec.

  The invention according to claim 6 is the continuous casting method of different steel types according to any one of claims 1 to 5, wherein the electromagnetic stirring device is operated from the front end of the post-charge.

  In the method of the means of claim 6, electromagnetic stirring is applied to the contaminated molten steel region immediately after casting, that is, the range from the front end of the post-charge, and the effect of electromagnetic stirring is reliably obtained.

  In the invention of claim 7, when the surface of the molten steel at the rear end of the precharge is lowered to a predetermined position in the mold below the mold top position, the drawing of the slab of the precharge is stopped or decelerated, and the precharge in the mold 7. A continuous casting method of different steel types according to any one of claims 1 to 6, wherein a connecting member having a partition plate is installed at the rear end of the molten steel.

  In the method according to the seventh aspect of the invention, when installing the connecting member having the partition plate, the connecting member and the cooling material are accurately installed because the drawing of the slab of the pre-charge is stopped or decelerated. be able to.

  The effect of the present invention is that the above-described means enables the molten steel portion immediately after the start of casting, which is contaminated with the residue of the precharge, to be solidified at an early stage. Furthermore, by performing electromagnetic stirring with a predetermined strength from a predetermined timing after the start of the injection of the molten steel in the post-charge, the effect of cooling the slab uniformly is obtained, the drift of the contaminated molten steel is suppressed, and the slab end portion is not The length of the stationary part can be shortened. Furthermore, the total effect of the use of cold material and electromagnetic stirring reduces the range of unsteady parts from the front end of the cast slab made of contaminated molten steel at the beginning of casting, and prevents deterioration of the cleanliness of the subsequent slab. it can. In the invention of claim 2, even if the mold has a taper, it can be dealt with. The contamination of the post-charge molten steel itself is reduced, and the extent of post-charge contamination can be prevented. The effect of the cold material is the same as in the case of the above-described claim 1, and the effect of electromagnetic stirring is also the same as that of the above-mentioned claim 1. The total of the above three effects can reduce the range of the unsteady portion from the front end of the slab in the initial casting portion, and can prevent the deterioration of the cleanliness of the subsequent molten steel.

In the invention of claim 3, a predetermined cooling effect can be obtained, and further, the solidification of the molten steel portion contaminated by the residue of the pre-charge can be solidified at an early stage, and the cleanliness of the subsequent molten steel can be improved. In the invention of claim 4, since the value obtained by dividing the amount of injection into the mold by the start of the electromagnetic stirring is within the range of 0 to 2700 kg / m ² , the timing of starting the electromagnetic stirring is delayed. Therefore, the slab can be uniformly cooled, and the influence of the drift of contaminated molten steel does not occur. In invention of Claim 5, the effect of uniform cooling of a slab is reliably acquired by electromagnetic stirring. In the sixth aspect of the invention, since the electromagnetic stirring is applied from the contaminated molten steel region immediately after casting, that is, from the front end of the post-charge, the effect of electromagnetic stirring can be reliably obtained. In the invention of claim 7, when installing the connecting member having the partition plate, the connecting member and the cooling material can be accurately installed because the drawing of the slab of the pre-charge is stopped or decelerated. .

  The best mode for carrying out the present invention will be described with reference to tables and drawings.

  In the continuous casting in which different steel types are continuously cast, in the method of the first embodiment, first, as shown in FIG. 1A, the molten steel 3a of the precharged steel type is removed from the tundish (not shown) of the mold 1 as shown in FIG. The inside is injected by the immersion nozzle 2. The injection is completed in a state where the molten steel surface 3c of the molten steel 3a is at a predetermined mold upper position 5 in the mold 1 slightly lowered from the mold top position 4. Next, as shown in (b), the slab is continuously drawn, and when the surface 3c of the molten steel 3a in the mold 1 is further lowered and reaches a predetermined mold lower position 6, the drawing of the pre-charged slab is temporarily stopped. To do. Next, the immersion nozzle 2 is removed from the mold 1. Next, as shown in (c), a connecting member having a steel partition plate 8 having a predetermined size smaller than the size of the slab is placed in the mold 1 so as to be in contact with the surface 3c of the precharged molten steel 3a. . Then, the slag film 7 attached to the inner wall of the mold 1 is removed and shown in (d). Next, the residue 10 on the partition plate 8 and between the outer periphery of the partition plate 8 and the mold inner wall 1a is removed and shown in FIG. Further, as shown in (f), a predetermined amount of iron or steel rod-like or whisker-like cooling material 9 is installed on the partition plate 8 and between the outer periphery of the partition plate 8 and the inner wall 1a of the mold 1. Thereafter, as shown in (g), injection of molten steel 3b of a different steel type of post-charge into the mold 1 from the immersion nozzle 2 was started, and as shown in (h), the molten steel surface 3d was raised to a predetermined height. At the time (when the value obtained by dividing the amount of the post-charge molten steel injected into the mold by the slab cross-sectional area becomes a predetermined value), the electromagnetic stirrer 11 is turned on to give the post-charge molten steel a predetermined strength. The magnetic stirring is applied. As shown in (i), after the molten steel surface 3c reaches a predetermined mold upper position 5 below the mold top position 4, the subsequent slab drawing is resumed. The removal of the residue 10 on the partition plate 8 and between the outer periphery of the partition plate 8 and the inner wall 1a of the mold may be at a practicable level and may not be complete removal. Moreover, if workability | operativity can be ensured, you may reverse the order of removal of said slag film 7, and installation of the connection member which has the partition plate 8. FIG. Further, the precharged molten steel surface 3c is preferably exposed by removing as much as possible the mold powder residue and molten powder layer at the rear end portion of the precharge before installing the connecting member. The connecting member may be installed in a state in which a little remains.

  In the method of the second embodiment, first, as shown in FIG. 2 (a), a molten steel 3a of a pre-charged steel type is injected from the tundish (not shown) into the mold 1 by the immersion nozzle 2. The injection is completed in a state where the molten steel surface 3c of the molten steel 3a is at a predetermined mold upper position 5 in the mold 1 slightly lowered from the mold top position 4. Next, as shown in (b), when the slab is continuously drawn and the surface 3c of the molten steel 3a in the mold 1 further decreases and reaches a predetermined mold lower position 6, the drawing speed of the pre-charged slab is reduced. To do. Next, the immersion nozzle 2 is removed from the mold 1, and then, as shown in (c), a connection member having a steel partition plate 8 having a predetermined size smaller than the size of the slab is precharged in the mold 1. It installs in contact with the surface 3c of the molten steel 3a. Then, the slag film 7 attached to the inner wall of the mold 1 is removed and shown in (d). Next, the residue 10 on the partition plate 8 and between the outer periphery of the partition plate 8 and the mold inner wall 1a is removed and shown in FIG. Further, as shown in (f), a predetermined amount of iron or steel rod-like or whisker-like cooling material 9 is installed on the partition plate 8 and between the outer periphery of the partition plate 8 and the inner wall 1a of the mold 1. Thereafter, as shown in (g), injection of molten steel 3b of a different steel type of post-charge into the mold 1 from the immersion nozzle 2 was started, and as shown in (h), the molten steel surface 3d was raised to a predetermined height. At the time (when the value obtained by dividing the amount of the post-charge molten steel injected into the mold by the slab cross-sectional area becomes a predetermined value), the electromagnetic stirrer 11 is turned on to give the post-charge molten steel a predetermined strength. The magnetic stirring is applied. As shown in (i), after the molten steel surface 3c reaches a predetermined mold upper position 5 below the mold top position 4, the slab drawing speed is returned to the original speed and the subsequent slab is drawn. .

  By setting it as these embodiments, the overflow of the molten steel 3b after injection | pouring can also be prevented as a post charge. In addition, it is possible to prevent the contamination range of the post-charge from being expanded, and to reduce the range of the unsteady portion related to the cleanliness of the initial casting portion of the post-charge slab.

  In these, the partition plate 8 of the connection member has a dimension of 50 to 98% of the length and width of the cross section of the slab, and further the thickness of the partition plate 8 is 1 to 20 mm, and continuous casting of different steel types is continued. Is preferred. In this way, most of the residue on the surface of the precharged molten steel is covered to reduce the contamination source of the molten steel, and even if a significant pipe is formed in the slab made of the molten steel of the precharge, it affects the postcharge at the connection part. Without being mechanically stable. Furthermore, by setting the partition plate 8 of the connection member to the above-described dimensions and thickness, the connection member can be reduced in weight, and the workability related to insertion and installation in the mold is improved.

Furthermore, the method of the third embodiment will be described. This method is the same as that in the above embodiment, and the connecting member and the cooling material 9 which are the partition plates 8 are made of iron or steel, and their total mass is divided by the cross-sectional area of the slab. This is a method in which continuous casting of different steel types is continued on the assumption that the value is 200 to 370 kg / m ² . By doing so, it is possible to cover all of the residues on the surface of the precharged molten steel. Furthermore, since the connecting member has a cooling ability for the molten steel (lower slab) in the vicinity of the connecting portion, by obtaining a predetermined cooling effect with the total amount of the connecting member and the cooling material, the residue of the precharge, etc. This makes it possible to solidify the molten steel part contaminated by early casting and improve the cleanliness of the subsequent molten steel. Furthermore, it does not impede workability related to the insertion and installation of cold material into the mold.

Furthermore, the method of the fourth embodiment will be described. This method is in the above embodiment, and when the value obtained by dividing the injection amount of molten steel into the mold of the post-charge by the slab cross-sectional area is in the range of 0 to 2700 kg / m ² , the switch of the electromagnetic stirring device 11 is turned on. It is a method to turn on and continue casting different steel types one after another. By doing so, the slab can be uniformly cooled without delaying the start timing of electromagnetic stirring, and the influence of the drift of contaminated molten steel does not occur.

  Furthermore, the method of the fifth embodiment will be described. This method is the same as that in the above-described embodiment, and the electromagnetic stirrer 11 is turned on to apply electromagnetic stirrer that gives a stirrer flow rate of an average flow rate of 10 to 130 cm / sec to the post-charge molten steel. This is a method to continue casting continuously. By doing in this way, the effect of uniform cooling of a slab is acquired reliably.

  Furthermore, the method of the sixth embodiment will be described. This method is the same as that in the above-described embodiment, and the electromagnetic stirrer 11 is a method in which continuous casting of different steel types is continued by using an electromagnetic stirrer 11 that can act on the post-charge molten steel above the mold lower position 6. is there. By doing in this way, electromagnetic stirring is made to act on the contaminated molten steel area immediately after casting, that is, the range from the front end of the post-charge, and the effect of electromagnetic stirring is reliably obtained.

  Further, a method according to the seventh embodiment will be described. This method is described in the first embodiment and the second embodiment described above, but the surface 3c of the molten steel 3a in the mold 1 is lowered from the mold top position, and a predetermined lower part of the mold. When the position 6 is reached, the drawing of the precharged slab is temporarily stopped, and a connecting member having a steel partition plate 8 having a predetermined size smaller than the size of the slab is placed in the mold 1 as a precharged molten steel 3a. When the surface 3c of the molten steel 3a in the mold 1 is lowered from the mold top position and reaches a predetermined mold lower position 6, the drawing speed of the precharged slab is reduced. Then, in the mold 1, by installing a connecting member having a steel partition plate 8 having a predetermined size smaller than the size of the slab so as to be in contact with the surface 3c of the molten steel 3a of the precharge, as described above, After injection as post-charge It prevents overflow of molten steel 3b, also it is possible to prevent the spread of contamination range of the rear charge, reducing the range of unsteady part regarding cleanliness casting early part of the rear charge slab.

  Embodiment 1 will be described below with reference to the tables and drawings. A continuous continuous casting machine continuously casts a JIS standard SUJ2 steel cross section of 380 mm x 490 mm as the precharge steel grade, followed by the precharge steel grade and the post-charge JIS standard. A bloom of 380 mm × 490 mm in cross-sectional area of SCM420 steel was continuously cast. For this reason, after the injection of the precharged molten steel 3a in the state where the molten steel surface 3c of the molten steel 3a of the precharge is located at the mold upper position 5 150 mm below the mold top position 4 within the mold 1, the casting is further performed. The piece was pulled out, and when the molten steel surface 3c reached the mold lower position 6 at a position 500 mm below the mold top position 4, the drawing of the cast piece was temporarily stopped. Next, a connecting member having a partition plate 8 having a cross-sectional area of 310 mm × 400 mm and a thickness of 10 mm was placed on the molten steel surface 3c. Next, the slag film 7 adhering to the mold inner wall 1a and other deposits on the mold inner wall 1a are removed, and the residue 10 on the partition plate 8 in the mold 1 and between the outer periphery of the partition plate 8 and the mold inner wall 1a. Was removed at a practicable level. Furthermore, a rod-shaped cold material 9 was installed on the partition plate 8, and a rod-shaped and whisker-shaped cold material 9 was installed between the outer periphery of the partition plate 8 and the inner wall 1 a of the mold 1. In this case, the total amount of the partition plate 8 and the cooling material 9 was 60 kg. Next, injection of the post-charge molten steel 3b is started, and when the molten steel surface 3d reaches a position 220 mm below the mold top position 4, it acts on the post-charge molten steel 3b above the position 500mm below the mold top position 4. The electromagnetic stirring apparatus which can be operated was started, and the electromagnetic stirring which gives an average flow velocity of 39 cm / sec was started. Further, after reaching the lower mold upper position 5 of 150 mm from the mold top position 4, the drawing of the slab was resumed.

  On the other hand, in Tables 1 to 3, the operation No. 1 to 25, whether or not the slag film 7 on the mold inner wall 1a is removed, whether or not the residue 10 on the partition plate 8 and between the outer periphery of the partition plate 8 and the mold inner wall 1a is removed, By changing the total mass per unit area of the connecting member having the plate 8 and the cooling material 9, the value obtained by dividing the injection amount of molten steel into the mold of the molten steel after the start of electromagnetic stirring by the slab cross-sectional area, and electromagnetic stirring Relative evaluation was shown about the countermeasure by five types of the average flow velocity given to the molten steel of a post-charge, and the effect of shortening of the unsteady part of the initial part of the casting of a post-charge slab. In this case, as for the effect of shortening the unsteady part at the initial stage of casting, those that are effective and those that are not effective by implementing the measures are evaluated in 40 stages and shown in Tables 1 to 3.

  Specifically, the operation No. in Table 1 is shown. The effect was scored by setting the unsteady part length at 4 to 108%. That is, the operation No. When the unsteady part length at 4 is 108%, the unsteady part length is less than 55% "40", and 55% or more but less than 57.5% is "39", 57.5% More than 60% is "38", 60% or more and less than 62.5% is "37", 62.5% or more and less than 65% is "36", 65% or more and 67.5% % Is "35", 67.5% or more and less than 70% is "34", 70% or more and less than 72.5% is "33", 72.5% or more and less than 75% Is "32", 75% or more and less than 77.5% is "31", 77.5% or more and less than 80% is "30", 80% or more and less than 82.5% "29", 82.5% or more and less than 85% "28", 85% or more and less than 87.5% "27", 87.5% or more and less than 90% "26", 90% or more and less than 92.5% "25", 92.5% or more and less than 95% “24”, 95% or more and less than 97.5% “23”, 97.5% or more and less than 100% “22”, 100% or more and less than 102.5% “21” "20" for 102.5% to less than 105%, "19" for 105% to less than 107.5%, "18" for 107.5% to less than 110%, 110% or more and less than 112.5% is “17”, 112.5% or more and less than 115% is “16”, 115% or more and less than 117.5% is “15”, 117. What is 5% or more and less than 120% is “14”, 120% or more and 12 Less than 5% is “13”, 122.5% or more and less than 125% is “12”, 125% or more and less than 127.5% is “11”, 127.5% or more and 130 % Is “10”, 130% or more and less than 132.5% is “9”, 132.5% or more and less than 135% is “8”, 135% or more and less than 137.5% Is "7", 137.5% or more and less than 140% is "6", 140% or more and less than 142.5% is "5", 142.5% or more and less than 145% Unsteady as “4”, “3” for 145% to less than 147.5%, “2” for 147.5% to less than 150%, “1” for 150% or more The overall effect of part shortening was evaluated.

  FIG. 3 is a diagram illustrating the definition of the unsteady part range on a graph showing the relationship between the distance from the slab end on the casting start side and the cleanliness. The example of the score “40” and the case of the score “12” Shows the unsteady part range on the graph. The score “40” is a case where the cleanliness is improved within a range close to the front end of the slab, and indicates a state where the unsteady part range at the initial stage of slab casting is short. On the other hand, the score “12” has a long distance from the front end of the slab until the cleanliness is improved, and the unsteady part range in the initial stage of slab casting is long.

  Further, a change in the total mass per unit area of the connecting member having the partition plate 8 and the cooling material 9, and a value obtained by dividing the amount of injection into the molten steel mold of the post-charge at the start of electromagnetic stirring by the slab cross-sectional area, In order to make it easy to understand the effect of the three types of measures of the average flow velocity given to the molten steel in the post-charge by electromagnetic stirring, simple evaluation (×, ○, ◎) was given. Specifically, “x” scores “20” to “31” were assigned to grades “19” and below, and “◎” were assigned to grades “32” and above.

In Table 1, operation Nos. 1 to 12 are similar representatives of the injection amount per unit area of the post-charge molten steel at the start timing of the electromagnetic stirring of the measure 4 and the average flow velocity given by the electromagnetic stirring of the measure 5. As conditions, the effects of the removal of the slag film of the countermeasure 1 and the removal of the residue of the countermeasure 2 and the mass change of the cooling member (cooling material and connecting member) of the countermeasure 3 are compared. Operation No. which does not take measures to set the mass per unit area of the cooling member (cooling material and connecting member) to 210 to 370 kg / m ² . In 1-4, the score of the effect of shortening the unsteady portion in the initial casting portion was “18” or less, and the simple evaluation was x. On the other hand, the operation No. which carried out the countermeasure which makes the mass per unit area of a cooling member (cooling material and a connection member) 210-370 kg / m < ² >. In 5 to 12, the rating of the effect of shortening the unsteady part in the initial casting portion was “22” or more, the simple evaluation was ◯ or ◎, and the effect of the cooling member was recognized. Further, the operation No. 1 in which the slag film removal of Measure 1 was not implemented In response to the rating “22” of the effect of shortening the unsteady portion of the initial casting portion at 5, 6, 9, and 10, operation No. 1 in which the slag film removal of Measure 1 was performed. In 7, 8, 11, and 12, the score of the effect of shortening the unsteady portion in the initial casting portion was improved to “28” or more. Furthermore, the operation No. in which the removal of the residue of the measure 2 is not carried out. No. 7 and No. 11 for the effect of shortening the unsteady portion in the initial casting portion of “No. The score of the effect of shortening the unsteady portion in the initial casting portions of Nos. 8 and 12 was improved to “36” and “40”. From the above, when the drawing of the slab is temporarily stopped and the connecting member having the partition plate 8 and the cooling material 9 are installed, the slag film 7 is removed, and the partition plate 8 and the partition plate 8 are removed. The removal of the residue 10 between the outer periphery and the inner wall 1a of the mold was carried out, and the value obtained by dividing the total mass of the partition plate 8 and the cold material 9 by the cross-sectional area of the slab was 200 to 370 kg / m ² . 8 and 12 were the most effective. Therefore, based on these, the invention according to claim 3 is that the value per unit area obtained by dividing the total mass of the connecting member having the partition plate 8 and the cold material 9 by the cross-sectional area of the slab is 200 to 370 kg / m ² . did.

In Table 2, operation Nos. 13 to 17 indicate the mass per unit area of the removal of the slag film of the countermeasure 1, the removal of the residue of the countermeasure 2 and the cooling member (the cooling material and the connecting member) of the countermeasure 3 to 200 to 370 kg / The effect of the electromagnetic stirring start timing of Measure 4 is compared with the average flow velocity given by the electromagnetic stirring of Measure 5 under the condition of implementing m ² . Regarding measure 4, operation No. in which the value obtained by dividing the amount of injection of molten steel into the mold of the post-charge when starting electromagnetic stirring by the cross-sectional area of the slab is in the range of 0 to 2700 kg / m ² . The score of the effect of shortening the unsteady portion in the initial casting portion at 13 to 16 was “36” or more, the simple evaluation was good with ◎, and the operation No. The rating of the effect of shortening the unsteady portion in the initial casting portion at 14 to 15 was particularly good at “38”. On the other hand, operation No. in which the value obtained by dividing the injection amount of the molten steel in the post-charge by the slab cross-sectional area was removed from the range of 0 to 2700 kg / m ² . In No. 17, the score of the effect of shortening the unsteady part in the initial casting part was “30”, and the simple evaluation was only ◯. In view of the above, in the invention according to claim 4, the upper limit of the value obtained by dividing the injection amount of the post-charge molten steel into the mold by the slab cross-sectional area when electromagnetic stirring is started is 2700 kg / m ² .

In Table 3, operation Nos. 18 to 25 indicate the mass per unit area of the removal of the slag film of the countermeasure 1, the removal of the residue of the countermeasure 2, and the cooling member (cooling material and connection member) of the countermeasure 3 in the range of 200 to 370 kg / Under the condition of implementing m ² , the effect of the average flow velocity given by the electromagnetic stirring of the measure 5 is compared as the start timing of the electromagnetic stirring of the measure 4 as a similar representative condition. Regarding measure 5, an operation No. with an average flow velocity given by electromagnetic stirring in the range of 10 to 130 cm / sec. In 19 to 21, 23 to 25, the rating of the effect of shortening the unsteady portion in the initial casting portion was good as “34” or more, and the simple evaluation was ◎. On the other hand, Condition No. 1 in which the average flow velocity given by electromagnetic stirring was removed from the range of 10 to 130 cm / sec. In 18 and 22, the rating of the effect of shortening the unsteady portion in the initial casting portion was only “28” and “30”. From the above, the invention according to claim 5 sets the average flow velocity given by electromagnetic stirring to 10 to 130 cm / sec.

  Furthermore, Example 2 is demonstrated with reference to a table | surface and drawing. Continuous casting of a JIS standard SUJ2 steel with a cross-sectional area of 380 mm x 490 mm in a vertical continuous casting machine, followed by a post-charge JIS standard SCM420 steel with a cross-sectional area of 380 mm x 490 mm Continuous casting. For this reason, in the mold 1, after the injection in the state where the molten steel surface 3 c of the molten steel 3 a of the precharge is located at the mold upper position 5 150 mm below the mold top position 4, the slab is further drawn, and the molten steel surface 3 c When the mold bottom position 6 was 450 mm below the mold top position 4, the slab drawing speed was reduced to 0.01 m / min. Next, in a state where the drawing speed is reduced, a connecting member having a partition plate 8 having a cross-sectional area of 310 mm × 400 mm and a thickness of 10 mm is installed on the molten steel surface 3c, and then the slag film 7 adhered to the mold inner wall 1a and the mold inner wall Other deposits 1a were removed, and the residue 10 on the partition plate 8 in the mold 1 and between the outer periphery of the partition plate 8 and the mold inner wall 1a was removed at a practicable level. Further, a rod-shaped cold material 9 was installed on the partition plate 8, and a rod-shaped and whisker-shaped cold material 9 was installed between the outer periphery of the partition plate 8 and the mold inner wall 1a. In this case, the total amount of the connecting member which is the partition plate 8 and the cooling material 9 is 60 kg. Next, injection of the post-charge molten steel 3b is started, and when the molten steel surface 3d reaches a position 280 mm below the mold top position 4, it acts on the post-charge molten steel 3b above the position 500mm below the mold top position 4. The electromagnetic stirring apparatus which can be operated was started, and the electromagnetic stirring which gives the average flow velocity of 32 cm / sec was started. Further, after reaching the lower mold upper position 5 of 150 mm from the mold top position 4, the drawing speed of the slab was returned to the original speed and the drawing was continued.

  On the other hand, in Tables 4-6, the operation No. 26-No. 50, whether or not the slag film 7 is removed from the inner wall 1a of the mold, whether or not the residue 10 is removed on the partition plate 8 and between the outer periphery of the partition plate 8 and the inner wall 1a of the mold, The change is made to the total mass per unit area of the cold material 9, the value obtained by dividing the amount of post-charge molten steel injected into the mold by the slab cross-sectional area at the start of electromagnetic stirring, and the post-charge molten steel by electromagnetic stirring. Relative evaluation was shown about the countermeasure by five types of average flow velocity, and the effect of shortening the unsteady part in the initial casting part of the post-charge slab. Regarding the effect of shortening the unsteady part in the initial casting part, the same score as in Table 1 was used, and the effective and ineffective effects were evaluated in 40 steps by implementing countermeasures, and shown in Tables 4 to 6 It was.

  Specifically, in Tables 4 to 6, the same evaluation as in Tables 1 to 3 was performed. That is, “40” when the unsteady part length is less than 55%, “39” when it is 55% or more and less than 57.5%, and “38” when it is 57.5% or more and less than 60%, “37” for 60% to less than 62.5%, “36” for 62.5% to less than 65%, “35” for 65% to less than 67.5%, 67. "34" is 5% or more and less than 70%, "33" is 70% or more and less than 72.5%, "32" is 72.5% or more and less than 75%, and 75% or more and 77 Less than 5% is “31”, 77.5% or more and less than 80% is “30”, 80% or more and less than 82.5% is “29”, 82.5% or more and 85 % Is less than 28%, 85% or more but less than 87.5% is "27", 87.5% or less "26" if it is less than 90%, "25" if it is 90% or more and less than 92.5%, "24" if it is 92.5% or more and less than 95%, 95% or more and 97.5% Less than “23”, 97.5% or more and less than 100% “22”, 100% or more and less than 102.5% “21”, 102.5% or more and less than 105% Some are “20”, 105% or more and less than 107.5% are “19”, 107.5% or more and less than 110% are “18”, 110% or more and less than 112.5% "17", 112.5% or more and less than 115% "16", 115% or more and less than 117.5% "15", 117.5% or more and less than 120% " 14 ”, those that are 120% or more and less than 122.5%“ 13 122.5% or more and less than 125% is “12”, 125% or more and less than 127.5% is “11”, 127.5% or more and less than 130% is “10”, 130 % Is less than 132.5% is "9", 132.5% is less than 135% is "8", 135% is less than 137.5% is "7", 137.5 % Is 140% or more and less than 142.5% is "5", 142.5% or more and less than 145% is "4", 145% or more and 147. The overall effect of shortening the unsteady part was evaluated with “3” being less than 5%, “2” being 147.5% or more and less than 150%, and “1” being 150% or more.

In Table 4, operation Nos. 20 to 37 are similar representatives of the injection amount per unit area of the post-charge molten steel at the start timing of the electromagnetic stirring of the measure 4 and the average flow velocity given by the electromagnetic stirring of the measure 5. As conditions, the effects of the removal of the slag film of the countermeasure 1 and the removal of the residue of the countermeasure 2 and the mass change of the cooling member (cooling material and connecting member) of the countermeasure 3 are compared. Operation No. ^{3 in} which the mass per unit area of the cooling member (cooling material and connecting member) of measure 3 is 150 to 160 kg / m ² . In 26-29, the score of the effect of shortening the unsteady part in the initial casting part was “16” or less, and the simple evaluation was x. On the other hand, the operation No. which performed the countermeasure 3 which makes the mass per unit area of a cooling member (cooling material and a connection member) 200-370 kg / m < ² >. In 30 to 37, the rating of the effect of shortening the unsteady part in the initial casting portion was “21” or more, the simple evaluation was “◯” or “◎”, and the effect of the cooling member was recognized.

Operation No. in which the effect of the cooling member was recognized. In Nos. 30 to 37, the operation No. in which the slag film removal of Measure 1 was not further performed. 30, 31, 34, and 35 are “21” for the effect of shortening the unsteady portion in the initial casting portion, whereas the operation No. 1 in which the slag film removal of Measure 1 was performed. In 32, 33, 36, and 37, the rating of the effect of shortening the unsteady portion in the initial casting portion was improved to “27” or more. Furthermore, the operation No. in which the removal of the residue of the countermeasure 2 is not implemented. While the scores of the effects of shortening the unsteady portion of the initial casting portions of 32 and 36 were “27” and “29”, both the removal of the slag film of Measure 1 and the removal of the residue of Measure 2 were performed. Operation No. The rating of the effect of shortening the unsteady portion in the initial casting portions of 33 and 37 improved to “35” and “39”. From the above, when the connecting member having the partition plate 8 and the cold material 9 are installed by decelerating the drawing of the slab, the removal of the slag film 7 of the measure 1 is performed and the partition plate 8 of the measure 2 and The value obtained by removing the residue 10 between the outer periphery of the partition plate 8 and the inner wall 1a of the mold and dividing the total mass of the partition plate 8 and the cold material 9 by the cross-sectional area of the cast piece is 200 to 370 kg / m ^2. No. 33 and 37 were the most effective. Therefore, based on these, the invention according to claim 3 is that the value per unit area obtained by dividing the total mass of the connecting member having the partition plate 8 and the cold material 9 by the cross-sectional area of the slab is 200 to 370 kg / m ² . did.

In Table 5, the operation No. 38 to 42, the removal of the slag film of Measure 1 and the removal of the residue of Measure 2 and the mass per unit volume of the cooling member (cooling material and connecting member) of Measure 3 are set to 200 to 370 kg / m ² The effect of the timing of starting electromagnetic stirring in measure 4 is compared using the average flow velocity given by electromagnetic stirring in measure 5 under the same conditions. Regarding measure 4, operation No. in which the value obtained by dividing the amount of injection of molten steel into the mold of the post-charge when starting electromagnetic stirring by the cross-sectional area of the slab is in the range of 0 to 2700 kg / m ² . The rating of the effect of shortening the unsteady part of the initial casting part in 38 to 41 is “35” or more, the simple evaluation is good with ◎, and the operation No. The score of the effect of shortening the unsteady portion in the early casting portions of 39 and 40 was particularly good as “37”. On the other hand, the operation No. in which the value obtained by dividing the injection amount of the molten steel in the post-charge by the slab cross-sectional area was removed from the range of 0 to 2700 kg / m ² . In 42, the score of the effect of shortening the unsteady part in the initial casting part was “29”, and the simple evaluation was only ◯. From the above, in the invention according to claim 4, the upper limit of the value obtained by dividing the injection amount of the post-charge molten steel into the mold by the slab cross-sectional area when electromagnetic stirring is started is 2700 kg / m ² .

In Table 6, the operation No. 43 ~ 50 implement the removal of the slag film of Measure 1 and the removal of the residue of Measure 2 and the mass per unit volume of the cooling member (cooling material and connecting member) of Measure 3 to 200 ~ 370kg / m ² The effect of the average flow velocity given by the electromagnetic stirring of the measure 5 is compared using the electromagnetic stirring start timing of the measure 4 as a similar representative condition. Regarding measure 5, an operation No. with an average flow velocity given by electromagnetic stirring in the range of 10 to 130 cm / sec. The score of the effect of shortening the unsteady portion in the initial casting portion at 44 to 46 and 48 to 50 was “35” or more, and the simple evaluation was good with ◎. In contrast, the operation No. in which the average flow velocity given by electromagnetic stirring was removed from the range of 10 to 130 cm / sec. In 43 and 47, the rating of the effect of shortening the unsteady part in the initial casting part was “27” and “29”, and the simple evaluation was only ◯. From the above, the invention according to claim 5 sets the average flow velocity given by electromagnetic stirring to 10 to 130 cm / sec.

  Further, when electromagnetic stirring is applied to the post-charge molten steel in the mold of claim 6, a method of applying electromagnetic stirring from the front end of the post-charge molten steel was carried out. By doing in this way, the post-charge molten steel was able to reliably impart the effect of electromagnetic stirring.

  Further, when the surface of the molten steel at the rear end of the precharge according to claim 7 is lowered to a predetermined position in the mold below the mold top position, in order to continuously cast different steel types in the postcharge, the drawing of the slab of the precharge is drawn. After stopping or slowing down, a method of installing a connecting member having a partition plate on the rear end of the molten steel of the previous charge was implemented. By doing in this way, the connection member which has a partition plate was able to be accurately installed in the rear end of the pre-charge, and the cold material could also be installed appropriately.

It is typical explanatory drawing of the process of a continuous casting in the case of stopping slab extraction temporarily, installing a connection member and a cold material, and carrying out electromagnetic stirring. It is typical explanatory drawing of the process of a continuous casting in the case of decelerating a slab extraction speed and installing a connecting member and a cold material. It is the figure which illustrated the definition of the unsteady part range on the graph showing the relationship between the distance from the slab end part by the side of casting start, and cleanliness.

Explanation of symbols

1 Mold 1a Mold inner wall 2 Immersion nozzle 3 Molten steel 3a Molten steel (pre-charge)
3b Molten steel (melted steel after charge)
3c Molten steel surface (pre-charged molten steel surface)
3d Molten steel surface (after-charge molten steel surface)
4 Mold top position 5 Mold upper position 6 Mold lower position 7 Slag film 8 Partition plate 9 Cold material 10 Residue 11 Electromagnetic stirrer

Claims (7)

  In continuous casting of different steel types, after installing the connecting member at the rear end of the precharged molten steel in the mold, before installing the postcharged molten steel, install the cold material and start the injection of the postcharged molten steel After that, when the value obtained by dividing the injection amount of the post-charge molten steel into the mold by the slab cross-sectional area becomes a predetermined value, electromagnetic stirring is applied to the post-charge molten steel to give a predetermined average flow velocity. The continuous casting method of different steel types characterized by shortening the unsteady part length which consists of contaminated molten steel of the post charge initial stage by this.   In continuous casting of different steel types, after a connecting member having a partition plate narrower than the slab size is installed at the rear end of the precharged molten steel in the mold, it adheres to the inner wall of the mold before injecting the molten steel of the rear charge. The remaining slag film is removed, the residue on the partition plate and between the outer periphery of the partition plate and the inner wall of the mold is removed, and further, on the partition plate of the connecting member and between the outer periphery of the partition plate and the inner wall of the mold. After installing the cold material, start the injection of the molten steel for the post-charge, and after that, when the value obtained by dividing the injection amount of the molten steel for the post-charge by the slab cross-sectional area becomes the predetermined value, the post-charge A continuous casting method of different steel types, characterized in that the length of the unsteady portion made of contaminated molten steel at the initial stage of post-charge is shortened by applying electromagnetic stirring to give a predetermined average flow velocity to the molten steel. The connection member and the cooling material are made of iron or steel, and a value obtained by dividing the total mass by the cross-sectional area of the slab is 200 to 370 kg / m ² . Continuous casting method for different steel types. 4. Electromagnetic stirring is started when the value obtained by dividing the amount of post-charge molten steel injected into the mold by the slab cross-sectional area is in the range of 0-2700 kg / m ^2. The continuous casting method of different steel types according to claim 1.   The continuous casting method of different steel types according to any one of claims 1 to 4, wherein the electromagnetic stirring gives a stirring charge flow rate of an average flow rate of 10 to 130 cm / sec to the post-charge molten steel.   The method for continuously casting different steel types according to any one of claims 1 to 5, wherein electromagnetic stirring is applied from the front end of the post-charge.   When the surface of the molten steel at the rear end of the pre-charge is lowered to a predetermined position in the mold below the top position of the mold, the drawing of the slab of the pre-charge is stopped or decelerated, and a partition is made at the rear end of the molten steel of the front charge in the mold. The continuous casting method of different steel types according to any one of claims 1 to 6, wherein a connecting member having a plate is installed.

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