JPH04224003A - Method and apparatus for casting and rolling thin slab - Google Patents

Abstract

PURPOSE:To offer a move complete manufacturing process for a thin slab for steel plate by adding a concept necessary to deal with various sizes of formed parts and to secure high quality of the formed parts in consideration of the level of the existing equipment technology. CONSTITUTION:Method for casting and rolling a thin slab characterized by rolling a solidified part of the thin slab cast by a belt-type thin slab continuous casting machine and its neighboring cast parts gradually by a multistage in-line rolling down equipment, then, executing the finish-rolling keeping the temp. over the transformation point Ar3 is offered. Since restraint for production followed by the size of the formed part is removed by the thin slab process of this invention, the production by the thin slab process is increased drastically and peeling of scale in the time of rolling can be carried out satisfactorily and a problem on surface defect coming from process troubles is solved. Further, the quality of the formed part, too, is improved and it is possible to manufacture a kind of sot steel which requires high workability which is especially a problem in the thin slab process and applicable kinds of steel are increased remarkably.

Description

[Detailed description of the invention]

0001

[Industrial Application Field] The present invention relates to a method and apparatus for casting and rolling thin slabs in the steel manufacturing process, which has been developed on a global scale in recent years. A thin slab with a thickness of 90 to 30 mm is cast, and the slab is directly sent to a hot rolling mill to produce a hot coil.

0002

[Prior Art] Slab casting and rolling in the conventional steel manufacturing process involves casting molten steel in a continuous casting machine in a thickness of 200 to 300 mm.
The slab is cast into a thick slab, and the slab is rolled in a hot rough rolling mill.
The coil was then rolled into a hot coil with a thickness of 4 to 1 mm using a hot finishing mill.

[0003] In recent years, the development of thin slabs is currently at a stage of vigorous progress, and various forms of thin slab processes have been published in the literature. For example, Han
s-Jurgen Ehrenberg eta
l. (Metallurgical Plant
and Technology Vol. 3 (19
89) and 52) presented the development results of the thin slab casting and rolling process in Mannesmann, and as a result showed an image of its application as an actual process. Also, Yujiro Nakamura et al. (Sumitomo Heavy Industries Technical Report Vol. 37, No. 110 (19
89) 31) shows the development results and equipment configuration of wide thin slab continuous casting equipment.

[0004]G. Holleys et al. (St
eel Times November (1989
) 605) describes Voest-Alpine's thin slab casting method, and the daily ``Tekko Shimbun'' (March 8, 1963 issue)
reported on the thin slab continuous casting method developed by Kawasaki Steel and Hitachi. These published documents are too numerous to list, but to summarize them, the continuous casting machine and equipment configuration for the thin slab casting process can be summarized as shown in FIG.

First, the continuous casting machine for thin slabs is Hans-J.
Uergen Ehrenbergetal. Various thin slab continuous casting machines have been shown, including those using fixed molds such as the SMS and SMS types, and those using belt-type moving molds as shown by Kawasaki Steel, Hitachi, and Yujiro Nakamura. . In the subsequent process, in Route A, the slabs that come out of the continuous casting machine are cut into predetermined lengths and then directly charged into a heat retention furnace that has a buffer function.
This is followed by finish rolling. Therefore, in route A, it is essential that the casting timing of the continuous casting machine and the rolling timing of the rolling mill are continuous in series, and this is a major feature. Another feature is that the slabs that come out of the continuous caster are sent to the finishing mill without being subjected to any processing (for example, bending by winding and unwinding) other than being cut. On the other hand, in Route B, the slabs that come out of the continuous caster for thin slabs are wound into coils in a winder, then charged into a heat retention furnace that serves as a buffer furnace, and spend time with the rolling mill. Make adjustments and
After that, it is mounted on an unwinding machine and finished rolled. Therefore, route B allows adjustment of the casting timing by the continuous caster and the rolling timing by the rolling mill.
Furthermore, it is characterized in that it attempts to avoid the disadvantages of a large surface area and large heat dissipation due to the thin slab by forming it into a coil.

[0006]

[Problems to be Solved by the Invention] The thin slab process disclosed in such documents is a mini-mill (annual production of 80~
1.6 million tons), and the process structure is designed to omit the rough rolling process by casting a thin slab, while at the same time placing emphasis on the use of sensible heat during casting. Therefore, in order to increase production volume, we need to increase speed, increase the size of finished products (particularly thickness and width), and improve quality (inner surface quality, material properties) to make it possible to manufacture high-grade steel. is not shown. Furthermore, if steel plates are cast and rolled using the same process configuration, there will be restrictions on the production volume, and at the same time, it is conceivable that rolling will not be possible in many cases depending on the steel type and product size.

[0007] The present invention aims to provide a more complete thin slab process for steel plates by adding concepts necessary for differentiating product sizes and ensuring product quality with the current equipment technology level in mind. It is something to do.

[0008]

[Means for Solving the Problems] The method for casting and rolling thin slabs according to the present invention involves multistage in-line rolling of the solidified part of a thin slab cast by a belt-type continuous thin slab caster and the casting parts before and after the solidified part. It is characterized in that it is gradually rolled in a facility and then finished rolled while being maintained at an Ar3 transformation point or higher.

Further, the thin slab casting/rolling apparatus according to the present invention includes a belt-type continuous casting machine, a dense split roll device, a multi-stage inline reduction equipment, a shearing machine, a coil winding machine, and a coil winding machine that immediately processes the wound coil. Coil heating equipment capable of keeping the slab at a predetermined location at a temperature above the Arc transformation point and for a predetermined time required to ensure quality is installed, followed by coil unwinding equipment. This equipment is equipped with a hot finish rolling mill equipped with crop shear descaling equipment and an edge heater installed as necessary, and performs hot finish rolling to the target product size.

0010

[Function] The function of the means of the present invention will be shown below. The entrance bar thickness of current hot finishing mills is 55 to 30 mm. Therefore, in order to omit the hot rough rolling process by thin slab casting, the casting thickness cast by the thin slab continuous caster needs to satisfy the finished entrance plate thickness of 55 to 30 mm.

However, when casting slabs in a continuous casting machine, immersion casting with an immersion nozzle is essential to prevent inclusions, but the minimum thickness that can be cast for this purpose is 4.
The casting thickness is 5 to 50 mm, preferably greater than this. Against this background, the conditions for increasing production volume and enabling multi-size manufacturing are as follows.

(a) Regarding the relationship between the entrance plate thickness of the current hot finishing rolling mill and the rolled product, as shown in Table 2 as an example, it is necessary to change the finishing entrance plate thickness depending on the product thickness. This is unavoidable due to the productivity, mill strength, and crown controllability of current hot finish rolling, and it is necessary to build in the slab thickness at least in accordance with the product thickness.

(b) According to the research conducted by the present inventors, when manufacturing thin steel sheets using thin slabs, the reduction ratio during hot rolling is small, so the composition of the hot rolled sheets remains coarse and the hot rolling The strength of the plate becomes insufficient or the ductility and toughness deteriorate. Furthermore, it was found that even after cold rolling and annealing, the texture was inappropriate and the mechanical properties deteriorated. In order to avoid this, it was found that the reduction ratio in hot rolling must be 60% or more, but for this purpose, the thickness of the hot rolled product is approximately 20 to 1 mm. It is necessary to satisfy the following conditions, and there is a restriction on the lower limit of the thickness of the slab that comes out of the continuous casting machine.

(c) For effective coil winding to avoid heat dissipation due to the increased surface area due to thinning of the slab, a thickness of 80 mm is the limit based on the current winding equipment capacity. For this reason as well, it is necessary that the continuous casting machine outlet thickness be 80 mm or less.

[0015] In order to satisfy these conditions and to enable casting with a belt-type continuous thin slab caster, a multi-stage inline reduction equipment is required within the continuous caster. The multi-stage in-line rolling in the present invention involves successively performing the so-called post-solidification rolling method and unsolidified rolling method in which the solidified part and the part in front of the solidified part where the slab is at high temperature and has low deformation resistance are rolled down in a continuous casting machine.
By combining the unsolidified rolling method and the post-solidified rolling method, a maximum rolling reduction of about 40 mm can be secured. Therefore, the maximum casting thickness that can produce a slab thickness of 50 mm, which is necessary to ensure product quality (ensuring a hot rolling rate of 60%) with a maximum thickness of 20 mm as a hot rolled product, is 90 mm. On the other hand, the easiest reduction amount in the in-line reduction method is 15 to 20 mm, but if the minimum thickness of 45 to 50 mm is cast by immersion casting and then in-line reduction, the slab becomes 30 mm.

[0016] Therefore, it is impossible to roll a slab cast to a thickness of 90 to 45 mm using in-line rolling equipment, and then remove the slab from the continuous casting machine with the thickness corresponding to the target hot finish rolling thickness. . Therefore, the significance of the multi-stage in-line rolling method of rolling the solidified part and the regions before and after the solidified part in the present invention will be explained in detail as follows.

<Metalradical merits of post-solidification rolling/non-solidifying rolling and rolling conditions at that time> The rolling actions and effects of the solidified area and its downstream vicinity can be summarized as follows.

(1) The fine precipitation of the second element existing in solid solution in steel as MnS, TiC, AIN, etc.
The aim is to promote precipitation through this rolling and shorten the pre-rolling holding time required for the next process of producing soft material.

(2) Similarly, since rolling is carried out at a high temperature of around 1200°C, the precipitation of MnS is greatly promoted,
To avoid embrittlement cracks in the second region of steel that exist at temperatures up to 1200°C and prevent embrittlement cracks during winding of a coil, etc.

(3) For thick products such as pipe materials, by applying a reduction of about 30% at around 1200°C, coarse γ of several mm is recrystallized and reduced to several hundred microns. , which improves toughness.

[0021] Specific conditions are exemplified as follows. (1) AI-K steel for continuous annealing...(1) above
In a temperature range where the average temperature of the target section is 1200℃ or less, the reduction rate is 5~
50% rolling. (2) Cold-rolled steel sheets for processing other than those mentioned above: (1) Post-solidification reduction with a reduction rate of 5% or more in a temperature range where the average temperature of the target section is 1300 to 1000°C. (3) Material with Mn/S<20: Rolling with a rolling reduction of 5% or more under conditions where the objective surface temperature of (2) above is 1200°C or more.

As an example of this effect, for example, the processing A of the embodiment
In I-K steel, the following effects can be obtained by performing post-solidification reduction at a cross-sectional average temperature of 1250° C. and a reduction rate of 10%. Lankford value (average value): approximately 0.1 to 0.2
Improved elongation: about 1 to 2% Improvement Yield stress: Decrease of about 1 to 2 kg/mm2 Next, the effects of reducing the unsolidified area near the solidified area can be summarized as follows. Since the part just before solidification is completed is in a semi-solidified state, (1) it can be rolled with a low load, and (2) if it is rolled while applying tension to the slab between each reduction roll, the flow in the semi-solidified part can be suppressed. In addition to preventing component segregation, it is also possible to (3) reduce and eliminate center porosity, (4) eliminate center cracks, and (5) refine the solidified structure by forming equiaxed crystals.

That is, the center porosity (3) is caused by volume condensation that occurs when the slab solidifies from a liquid to a solid during the solidification process, but it can be reduced and even eliminated by compensating for the shrinkage volume by rolling. It is.

Regarding the central crack in (4), when local confinement occurs when solidifying from liquid to solid at the crater end (solidification completion point) as in (3), molten steel is not supplied to that part and the line It occurs as a shaped or planar crack. The volume is compensated by this rolling, and at the same time, the upper and lower solidified parts are pressed together.

Regarding (5), solidification nuclei are generated by rolling down and the formation of equiaxed crystals is promoted. This causes the coarse solidified structure to become finer.

[0026] Specifically, in a continuous caster, slabs with a solidification rate between 0.5 and 1.0 mm are rolled down by a plurality of reduction rolls (multi-stage inline reduction rolls) with a total reduction amount of 1 minute. Roll down to 0.5 to 2.0 mm. As a result, effects as shown in Table 1 can be obtained.

[0027]

[Table 1]

Next, in the belt-type continuous thin slab casting machine of the present invention, it is preferable that the short sides also be moved in synchronization with the belt. This is essential from the viewpoint of ensuring slab quality and operability, but the width of a thin slab of 30 to 90 mm cannot be changed significantly by rolling. Therefore, it is necessary to create products corresponding to various required product widths at the casting stage using a continuous casting machine. Therefore, 600~2200
Thickness is 30-90m compared to the current product width range of mm.
In the case of a slab of m, it is necessary to temporarily stop casting in the continuous caster and change the casting width for each lot of product width.

[0029] However, in the present invention, this problem has been solved by
This problem can be solved by introducing the inventions described in JP-A-183757, JP-A-63-264252, JP-A-63-264251, etc. into the present continuous casting process.

[0030] As described above, the present invention makes it possible to manufacture products with good internal quality in a range of product sizes that cannot be handled by conventional known processes by using the multi-stage inline reduction equipment and the continuous casting machine described above. Increase production.

[0031] Further, the present inventors investigated in detail hot-rolled products and cold-rolled products manufactured by the A route process shown in FIG. 1, which is a known process, and found that there were many scale defects on the product surface. Ta. The reason for this is that in this process, current descaling equipment cannot completely remove scale present on the surface of the slab before finish rolling. In the conventional thick continuous casting process, Vertical Scale B is applied to the scale of the slab.
After applying processing using a reaker (VSB) or the like to make it easier to peel off from the iron base material, the scale is removed using descaling equipment. However, in the A route process, the slab is directly descaled without undergoing any processing after casting. The present inventors have discovered that scale on an as-cast slab penetrates deeply into grain boundaries. At the same time, we have found that it is advantageous to apply bending strain, tensile strain, and rolling strain in the width direction to the surface of the slab in order to facilitate the peeling off of such scales. Conventional VSB is effective in this respect as well, but in the thin slab process, the slab is thin, so when VSB is applied, the slab tends to buckle in the width direction. The present inventors believe that in order to solve this problem, the slab is wound up immediately after casting as shown in route B in Fig. 1.
We have found that it is most effective to apply bending strain to the surface by unwinding.

[0032] The purpose of route B in the known literature is:
Although the heat dissipation of the cast billet was avoided and sensible heat was effectively used, the present invention emphasizes that this winding and unwinding function is also essential for perfect descaling.

Furthermore, the present invention provides the best method for completely descaling before hot finishing rolling, by unwinding the cast slab at the exit point of the continuous caster before finishing rolling. It was discovered that the rewound slab can be rapidly descaled. Therefore, it is desirable that the unwinding equipment and the descaling equipment be located as close to the finishing mill as possible.

[0034] Next is a means for making the material characteristics of the product the target characteristics. That is, in the thin slab process, as shown in (b) above, the reduction ratio in hot rolling is small, so the structure of the hot rolled sheet remains coarse, resulting in insufficient strength, ductility, and toughness depending on the steel type. The necessary means for this purpose is to secure the aforementioned rolling reduction ratio, but for steel types that require high ductility and drawability, it is also necessary to control the morphology of precipitates such as MnS, and for high tensile strength materials, it is necessary to control the morphology of precipitates such as Ti,
It is necessary to maintain a solid solution of precipitation hardening elements such as Nb.

Regarding this point, the present inventors have discovered that in order to control the form of these precipitates and maintain solid solution, after the continuous slab is wound up with a winding device on the exit side of the continuous casting machine, It was found that this can be controlled by controlling the holding temperature and holding time during unwinding. And this retention time is the Ar of the material.
It was found that the temperature is basically 3 or more points, and that the temperature and holding time differ depending on the steel type. According to conventionally known documents, after the slab is rolled up, there is no additional purpose for the period during which it is unrolled other than to use it as a buffer heat retention furnace between continuous casting and rolling. The purpose is to enable the coil to be held in a heat retention furnace at a required temperature for a required period of time depending on the steel type, and to control the form of precipitates and maintain solid solution depending on the steel type.

[0036] In thin-wall continuous casting, since the cooling rate is slow,
Although the second element in steel is frozen in a solid solution state, precipitation also occurs in a finely dispersed state. In this case, although it is said to be in a solid solution state, it often becomes fine precipitates due to the coiling and holding after hot rolling, so the material after hot rolling hardens. Therefore, in order to produce soft cold-rolled steel sheets, it is necessary to maintain the temperature at a high temperature above the A3 transformation point, and allow precipitates such as MnS, TiC, and AIN, which are finely precipitated at high temperatures, to grow and coarsen to reduce their effect on strength. It is necessary to do so.

[0037] Therefore, the following conditions (A) and (B) are required.
Examples are the main focus. (A) The entire length and entire cross section of the AI-K steel coil for continuous annealing can be maintained at 1050° C. or higher for 15 minutes or longer in a heat retention furnace. (B) The entire length and entire cross section of the steel coil for cold steel sheets for processing other than those mentioned above can be maintained at 1050 to 1200°C for 10 minutes or more in a heat retention furnace.

As a result, as shown in Example [2], a soft cold-rolled steel sheet having a low yield stress and a high Lankford value (average value) can be obtained.

[0039] Therefore, the heat retention furnace is not just a buffer furnace, but is characterized in that it has active heat retention and heating functions. As shown in Figure 2, we ensured that the temperature of the edge and top slab parts at a high temperature was maintained at a high temperature, which was also present in the simulation results with a moving time of only 3 to 5 minutes, and the temperature of the entire cross section was maintained at a high temperature. It has the function of making the material properties of the finished product uniform over the entire length and width.

[0040] It is also possible to compensate for the slight temperature at the edge of the slab by using an edge heater installed in front of the hot finish rolling. If this edge heater is installed as necessary depending on production volume, steel type, steel type composition, etc., it will become an effective quality assurance equipment.

The main technical means of the present invention have been described above, but other means include dense split rolls for preventing bulging in a continuous caster, cooling equipment, slab shearing equipment, dummy bar pulling equipment, descaling equipment, etc. This method employs well-known technology in the industry.

The hot finishing mill to which the present invention is applied may be a continuous multi-stage finishing mill that is widely used in integrated steel manufacturers, or may be a single rolling facility such as a Steckel mill. In particular, in the former, Cropshire,
It is a natural premise that necessary equipment for a finishing rolling mill, such as a runout table and a coiler, be included.

[0043]

[Examples] Examples of the present invention will be described below. As shown in FIG. 3, the embodiment of the present invention is a process in which a belt-type thin slab continuous casting machine 1 and the following equipment are arranged in relation to it. That is, thickness 90-30mm, width 600-2200mm
A belt-type thin slab continuous caster 1 that casts slabs of mm in diameter is used, for example, to control slab quality at a movable short side (not shown) that moves in synchronization with the belt and can change slab width, as well as at a secondary cooling zone. Dense split roll 4 for preventing bulging to ensure sufficient
The continuous casting machine 1 is equipped with cooling equipment (air-water cooling equipment) 2, and in-run rolling equipment 3 that rolls the solidified part and the parts in the vicinity before and after it in multiple stages to reduce the thickness of the slab according to the target finish rolling thickness.
On the outlet side, there is a shearing equipment 5 that can quickly cut the slab into a predetermined length while synchronizing with the moving speed of the slab, a dummy bar pulling device 7, and one or several stages of coil winding devices 6 and coils. A transfer machine (lifting type) 9 is arranged. Furthermore, the equipment has a soaking/heating function that allows the coil wound by the coil winding device 6 to be received from the coil transfer machine 9 and loaded immediately or from the heat-retaining coil box freight car 14 at the rear of the equipment. A tunnel-type coil heating furnace 8 capable of holding the slab above the Ar3 transformation point and for a predetermined time required to ensure quality is installed, and after the coil holding for the predetermined time is completed, the transfer machine 13 descales the slab. The coil is unwound by being attached to a coil unwinding equipment 11 disposed on the entry side of a hot finishing rolling mill 10 equipped with equipment and an edge heater installed as necessary. and delay table 1
2. This is a thin slab casting and rolling process in which descaling is performed on the exit side, edge heating is performed as necessary, and then hot finish rolling is performed to the target finished product size. Note that, in addition to the equipment for the above-mentioned functions, there is no restriction on the arrangement of equipment added to finishing rolling, such as bar joining equipment and width adjustment equipment, on the front side of the hot finishing rolling mill.

The casting conditions in the continuous casting machine 1 shown in FIG. 3 are as follows. Casting thickness: 50mm, Coil thickness: 50-35mm Casting width: 700-2100mm Casting speed: max 10m/min Machine length: 30m Inline reduction capacity: max 15mm Steel type: A
I-K Here, the width variable/moving short side equipment is disclosed in Japanese Patent Application Laid-open No. 63-1837.
No. 57, JP-A No. 63-264252, the in-line reduction rolling equipment 3 includes a solidified part consisting of three tension-rollable segments with a maximum reduction capacity of 400 tons, an unsolidified part before and after the solidified part, and a solidified part. By rolling, it has a maximum rolling capacity of 15 mm.

[1] Production Capacity In the equipment shown in Figure 3, the production volume when a casting with a thickness of 50 mm is rolled as it is and rolled with a hot finishing mill, and the production volume when a casting with a thickness of 50 mm is rolled with in-line reduction and a hot-rolled product is produced. The production volume when rolling the slab coil to a thickness of 50 to 30 mm was verified based on production results in actual operations. In addition, the slab coil thickness according to the hot-rolled product thickness in this case is shown in Table 2. In this case, the width of the product was 700 to 2100 mm during casting.

[0046]

[Table 2]

[0047] Looking at the production results, in the case of a single size slab coil with a thickness of 50 mm
30,000 tons/month Slab coil thickness 50
When adjusted to ~30mm, it becomes 370,000 tons/month, which proves that the installation of inline reduction will increase the production volume for the thin slab process by more than 10 times, and dramatically increase the number of steel types applicable to the thin slab process.

[2] Casting speed 10 mm using the equipment shown in Figure 3
/min, casting thickness 50m cast to slab width 1200mm
m slab is reduced to 35 m by in-line reduction equipment 3.
After making the coil thickness 5.0 mm, it was cut into a 10 m long slab using a running cutting machine, and the coil was charged into the box-shaped heating furnace and immediately rolled to a product thickness of 5.0 mm using a hot rolling mill. A test simulating the A route in Figure 1 (this is called the A route) and the coil winding device 6 in Figure 3 were used to test 40 tons.
The winding device is immediately reversed to unwind the coil, and the steady section is cut into a 10m long slab using a running cutter. Immediately it is charged into a box-shaped heating furnace, and immediately transferred to a hot rolling machine. B in Figure 1 was obtained by rolling the product to a thickness of 3.0 mm.
In a test simulating the route (this is called route B), the coil was wound into a 40 ton coil using the coil winding device 6 shown in Fig. 3, and then covered with a heat insulating cover and held for 20 minutes.
After that, the winding device is reversed to perform unwinding, and the steady section is cut into a 10 m long slab using a running cutting machine. Immediately, the slab is charged into a box-shaped heating furnace, and immediately heated to a hot rolling mill to reduce the thickness of the finished product to 5.5 m. 0m
Three routes (referred to as the "invention route") were conducted on 10 slabs each, simulating the present invention rolled to a thickness of 100 mm, and the surface defects and mechanical properties after cold rolling and annealing were investigated. Detailed manufacturing conditions and manufacturing results in this case are shown in Tables 3 and 4.
As shown.

[0049]

[Table 3]

[0050]

[Table 4]

As a result, as mentioned above, the A root material cannot sufficiently remove the scale generated during casting, resulting in a high occurrence rate of scale defects in cold-rolled sheets.

On the other hand, the scale defects of the B root material and the root material of the present invention, which are processed into coils by winding and unwinding, are drastically reduced, and good products can be obtained.

Further, the above-mentioned effect of maintaining the high temperature of the coil can be obtained by comparing the B root material and the root material of the present invention. That is, since the root material B and the root material of the present invention were AI-K, a difference of 20 minutes in holding time was made at 1050°C, which made it possible to control the precipitation of MnS, and the Lankford value (average value) It has been found that it is possible to produce a soft material with low yield stress, which is said to be difficult to produce using a thin slab process.

[0054]

[Effects of the Invention] As described above, the thin slab process of the present invention removes the production constraints associated with the product size, so the production volume by the thin slab process can be dramatically increased, and the scale can be removed sufficiently during rolling. Surface defect problems caused by process problems are eliminated. Furthermore, the quality of the finished product is improved, and it becomes possible to manufacture steel types that require high workability from soft materials, which are a particular problem in the thin slab process, significantly increasing the number of applicable steel types.

[Brief explanation of the drawing]

FIG. 1 shows an example of a known thin slab manufacturing process.

FIG. 2 is a diagram showing an example of temperature changes in a slab coil from casting to before rolling.

FIG. 3 is a diagram showing an example of thin slab casting/rolling equipment of the present invention.

[Explanation of symbols]

1 Belt type thin slab continuous casting machine 2 Cooling equipment 3 In-line reduction equipment 4 Dense split roll 5 Shearing equipment 6 Coil winding device 7 Dummy bar extraction device 8 Tunnel type coil heating furnace 9 Coil transfer machine 10 Hot finishing press back machine 11 Coil unwinding equipment 12 Delay table 13 Transfer machine 14 Insulated coil box freight car

Claims (2)

[Claims] [Claim 1] The solidified part of a thin slab cast by a belt-type thin slab continuous caster and the cast parts before and after the solidified part are gradually rolled in a multi-stage inline rolling equipment, and then maintained at the Ar3 transformation point or higher. A thin slab casting and rolling method characterized by finish rolling. [Claim 2] Belt type continuous casting machine, dense split roll device, multi-stage inline reduction equipment, shearing machine, coil winding machine,
Furthermore, following this, coil heating equipment is capable of immediately conveying the coil wound by the coil winding machine and keeping the coil at a predetermined position at a temperature above the Arc transformation point and for a predetermined time period necessary to ensure quality. This is followed by a coil unwinding facility, followed by a hot finishing mill equipped with a crop shear, descaling facility, and an edge heater installed as necessary to achieve the target product size. Thin slab casting and rolling equipment that performs hot finish rolling.