DESCRIPTION
CASTING EQUIPMENT AND CASTING METHOD USING SAME
TECHNICAL FIELD
[0001] The present invention relates to a casting installation and a casting method
using the same, and more particularly, to a casting installation that may easily produce a
slab for an extremely thick steel material and enhance quality, yielding percentage, and
productivity of the slab and to a casting method using the same.
BACKGROUND ART
[0002] In general, an extremely thick steel material has a thickness of at least 100
mm, and internal quality such as porosity and mechanical properties such as impact and
toughness of the extremely thick steel material are managed with a thickness reduction
ratio (slab thickness/product thickness) limited according to an intended use. For example,
as marine structural steel, there is required an extremely thick steel material having the
thickness reduction ratio of 4 or more and pressure steel and wind power structural steel
requires the thickness reduction ratio of 3 or more.
[0003] Currently, an extremely thick steel material may be produced through
predetermined post-processes such as forging and rolling of an ingot or slab produced by a
continuous casting process. When an extremely thick steel material is produced by the
ingot process, i.e., the former method, the ingot is produced into an extremely thick steel
material product by a forging process or is subject to an additional rolling process. In
particular, since the extremely thick steel material requiring a high thickness reduction
ratio regards the internal quality as an important factor, a slab mostly cast in an ingot is

subjected to a forging operation and then produced through a rolling process.
[0004] As such, producing an extremely thick steel material by using a slab cast
in an ingot may correspond to the production of an extremely thick steel material having a
high thickness reduction ratio and has an advantage for the production of a small-lot in
consideration of a demand characteristic of the extremely thick steel material. However,
the slab produced by using the ingot process requires cutting of an unsound region for
removing the unsound region generated around a riser and a main riser. Thus, deterioration
in yielding percentage of the slab is caused due to cutting of upper and lower regions of the
slab, so that production costs for producing the extremely thick steel material is increased.
[0005] Meanwhile, when an extremely thick steel material is produced by the
continuous casting process, i.e., the latter method, in general, the extremely thick steel
material is produced by a method of rolling a slab subject to a continuous cast. Although
the latter method is excellent in yielding process and thus superior to the ingot process in
terms of production costs when compared to the ingot process, there is a problem in that a
thickness of the extremely thick steel material is also limited due to a limited slab thickness
when steel products requiring a high thickness reduction ratio are produced.
[0006] Further, since the extremely thick steel material is relatively thick
compared to a normal slab, it takes a long time until the slab is completely solidified after
being cast. When a slab for an extremely thick steel material thicker than a general slab
produced by a general caster is produced by a conventional casting method in which
molten steel is continuous cast and cut, solidification is completed to an inside of the slab
and thus the installation of the caster becomes very long for a cutting process, which leads
to enlargement of the installation, resulting in consumption of enormous initial cost in
terms of production costs.

[0007] la addition, since possibility in which an internal defect of the slab occurs
is high compared to an ingot material, there is a high possibility in which an internal defect
in a continuous cast slab may remain in the extremely thick steel material. In addition,
since a continuous cast installation for producing a slab is optimized for mass production,
there is a disadvantageous problem in terms of production of a small-lot.
[0008] Thus, development of new installation and process is urgently required for
producing a slab for extremely thick steel material having a high thickness reduction ratio,
the slab being not easy to be produced in a general casting installation. That is, required is
an installation and process which is capable of enhancing internal quality and yielding
percentage same as or better than an ingot slab in terms of steel quality, is advantageous in
producing various kinds of small-lot extremely thick steel materials in terms of production,
and is capable of enhancing productivity compared to the production of the ingot slab.
DISCLOSURE OF THE INVENTION
TECHNICAL PROBLEM
[0009] The present invention provides a casting installation easily producing a
slab for an extremely thick steel material and to a casting method using the same.
[0010] The present invention also provides to a casting installation capable of
enhancing quality and yielding percentage of a slab and to a casting method using the same.
[0011] The present invention also provides to a casting installation capable of
enhancing productivity of a slab and efficiency of a process installation and to a casting
method using the same.
TECHNICAL SOLUTION
[0012] A casting installation according to an embodiment of the present invention
includes: a casting unit defining a passage through which molten steel passes and for

casting the molten steel into a slab; and a solidification unit including: a support unit
disposed spaced apart from the casting unit and receiving the slab from the casting unit and
disposed on at least any one place of sides of the slab to support the slab; and a first quality
controller provided on an outside of the slab to induce solidification of the slab.
[00l3] The first quality controller may include: a first stirrer disposed in
proximity to an outside of the slab and able to elevate in a longitudinal direction of the
slab; a second stirrer provided spaced apart below the first stirrer and able to elevate in the
longitudinal direction of the slab; and a first heater installed so as to be able to move
forward and backward in a region directly above the slab and configured to heat an upper
portion of the slab.
[0014] The first stirrer may have coils wound around the slab and disposed in the
form of a circle.
[0015] The casting unit may include: an accommodation unit having a space in
which the molten steel is accommodated; a drawing machine drawing the slab from the
accommodation unit to a lower portion; and a second quality controller provided on an
outside of the passage.
[0016] The accommodation unit may include a mold configured to form the
passage through which the molten steel supplied to a tundish passes, and the mold may be
formed so that the slab has a thickness of 800 mm or less and a width of 2000 mm or less.
[0017] The second quality controller may include: a stirring unit including at least
one stirrer disposed on an outside of the mold and configured to stir at least any one of the
molten steel and unsolidified molten steel inside the slab; a second heater installed so as to
be able to move forward and backward in a region directly below the mold and configured
to heat an upper portion of the slab.

[0018] The stirring unit may include: a third stirrer disposed in proximity to the
mold and able to elevate in a drawing direction of the slab; a fourth stirrer provided spaced
apart below the third stirrer and able to elevate in the drawing direction of the slab.
[0019] The third stirrer may have coils wound around the mold or the slab and
disposed in the form of a circle.
[0020] A pusher for separating the slab from the drawing machine may be
provided to the casting unit and the pusher may be installed so as to be able to reciprocally
move forward and backward toward the solidification unit.
[0021] A transfer unit transferring the slab from the casting unit to the
solidification unit or from the solidification unit to an outside of the solidification unit may
be provided.
[0022]
[0023] A casting method according to an embodiment of the present invention
includes: providing molten steel to prepare casting; casting the molten steel in a casting
unit allowing a passage through which the molten steel passes to be opened or closed;
transferring a slab produced through the casting to a solidification unit; and transferring the
slab to a post-process after solidification of the slab is completed.
[0024] The casting of the molten steel may be repeated in the casting unit after
the slab is transferred to the solidification unit.
[0025] When the casting of the molten steel is repeated, the transferring the slab
to the solidification unit may be performed while the molten steel is transferred to the
casting unit so that preparing the casting is performed.
[0026] When the casting of the molten steel is a single casting, that is one time
casting, the solidification of the slab may be completed in the casting unit or after the slab

is transferred to the solidification unit.
[0027] The molten steel may be cast at a casting rate 0.3m per minute or less.
ADVANTAGEOUS EFFECTS
[0028] According to a casting installation and a casting method using the same
according to embodiments of the present, invention, it is possible to improve yielding
percentage of a slab produced by a continuous casting. That is, when a slab cast in a
casting unit is solidified in a casting unit or a solidification unit, the length of a pipe
generated at an upper portion of the slab is reduced to enhance yielding percentage of the
slab by delaying solidification of the upper portion of the slab by using a second heater or a
first heater.
[0029] In addition, molten steel remaining in a mold is stirred to enhance inner
quality during casting and unsolidified molten steel in slab is stirred after a casting is
completed, so that the equiaxed crystal ratio in the slab may be enhanced, segregation and
porosity may be reduced, and an internal defect such as a pipe occurring at an edge end of
the slab may be reduced.
[0030] In addition, according to the present invention, - it is possible to
continuously cast another slab in a casting unit during a process in which solidification of a
slab is performed in a solidification unit. Thus, since a process required for solidification of
an extremely thick steel material may be completed in the solidification unit, a casting of
molten steel may not stop, thus capable of improving productivity of a slab and efficiency
of a process installation.
BRIEF DESCRIPTION OF THE DRAWINGS
[0031] FIG. 1 illustrates a view of a casting installation according to an

embodiment of the present invention.
[0032] FIG. 2 illustrates a flow chart of a casting method according to an
embodiment of the present invention.
[0033] FIG. 3 illustrates a view of an operating state of a casting installation
according to a casting method in FIG. 2.
MODE FOR CARRYING OUT THE INVENTION
[0034] Hereinafter, specific embodiments will be described in detail with
reference to the accompanying drawings. The present invention may, however, be
embodied in different forms and should not be construed as limited to the embodiments set
forth herein. Rather, these embodiments are provided so that this disclosure will be
thorough and complete, and will fully convey the scope of the present invention to those
skilled in the art. Like reference numerals refer to like elements throughout.
[0035]
[0036] FIG. 1 illustrates a view of a casting installation according to an
embodiment of the present invention. FIG. 2 illustrates a flow chart of a casting method
according to an embodiment of the present invention. FIG. 3 illustrates a view of an
operating state of a casting installation according to a casting method in FIG. 2. FIGS. 3 A
to 3F illustrate changes in the casting installation working to produce slab.
[0037] Referring to FIG. 1, a casting installation 1 as an installation to produce a
slab for an extremely thick steel material according to an embodiment of the present
invention includes a casting unit la defining a passage through which molten steel passes
and for casting the molten steel into a slab; and a solidification unit lb including: a support
unit 500 disposed spaced apart from the casting unit la and receiving the slab from the

casting unit la and disposed on at least any one place of sides of the slab to support the
slab; and a first quality controller 600 provided on an outside of the slab to induce
solidification of the slab.
[0038] The casting unit la as a section in which continuous casting of refined
molten steel is carried out includes: an accommodation unit 100 accommodating the
molten steel; a drawing machine 200 drawing the slab from the accommodation unit 100 to
a lower portion; and a second quality controller 300 provided on an outside of the passage
through which the molten steel passes.
[0039] The accommodation unit 100 defines a space accommodating molten steel
before the casting of the molten steel and includes a ladle 120 accommodating molten steel,
a tundish 140 receiving the molten steel from the ladle 120, and a mold 160 disposed
spaced apart below the tundish 140.
[0040] The ladle 120 is a container for accommodating molten steel after refining
is completed and may be produced in various hollow shapes having an internal space
capable of accommodating the molten steel. In general, the ladle 120 may be provided in
plurality to increase the circulation rate of a continuous casting installation.
[0041] The tundish 140 is produced in the shape of a hollow container capable of
accommodating the molten steel supplied from the ladle 120. An outlet discharging molten
steel is formed in the bottom of the tundish 140, so that the molten steel accommodated in
the tundish 140 may be discharged to the outside through the outlet. The molten steel
accommodated in the tundish 140 stays inside the tundish 140 for a period of time, thus
being poured into the mold 160 after flotation of inclusion contained in the molten steel.
[0042] The mold 160 is provided for shaping the molten steel poured from the
tundish 140 in an appropriate size to produce a slab, thus defining width and thickness of a

passage through which the molten steel passes. The mold 160 of the present invention may
be formed such that a slab has a thickness of 800 mm or less and a width of 2000 mm or
less in order to cope with the size of a slab for an extremely thick steel material. That is,
use of the mold 160 having a greatly increased thickness compared to a mold of a
conventional casting installation allows a slab subjected to forging and rolling processes to
have a thickness used for the extremely thick steel material.
[0043] Meanwhile, there may be provided a guide roll 170 guiding a slab having
an initial shell to the outside of the mold 160 through the mold 160, a cooling nozzle (not
shown) cooling the slab guided from the guide roll 170, and a vibrator (not shown)
transmitting vibration to the mold 160 so that the slab inside the mold is easily drawn to
the outside of the mold 160. In the present invention, it is not necessary to particularly limit
the configuration of the guide roll 170, the cooling nozzle, and the vibrator, but various
configurations and operating methods thereof are already widely known to those skilled in
the art, so that a detailed description thereof will be omitted.
[0044] The drawing machine 200 as a machine for drawing a slab from the
accommodation unit 100 to a lower portion, includes: a surface plate 220 which is initially
disposed inside the mold and receives molten steel to prevent the molten steel from spilling
downwards from the mold 160 and connects the primary solidified slab to an actuator 240,
and the actuator 240 drawing the slab to the lower portion.
[0045] The surface plate 220 is provided for connecting a slab to the actuator 240,
and a plate having a specific-shaped surface is used for easy connection to the slab.
Although the present invention does not limit the shape and the material of the surface
plate 220, it is preferable that the surface plate 200 is made of such a material that does not
lead to deformation which may be caused by to a slab of a high temperature when being in

contact with the slab.
[0046] The actuator 240 is a device for lowering the surface plate 220, and a slab
connected to the surface plate 220 may be drawn downwards by lowering the surface plate
220 connected to the actuator 240. The actuator 240 may employ a device capable of
descending to a lower portion when the slab is drawn and ascending at an initial stage of
casting so that the surface plate 220 is positioned inside the mold 160. That is, a device
capable of descending and ascending may be used as the actuator 240.
[0047]
[0048] The second quality controller 300 is provided for improving quality of a
slab drawn from the drawing machine 200 and includes: a stirring unit 320 including at
least one stirrer disposed on an outside of the mold 160 and configured to stir at least any
one of molten steel in the mold 160 and unsolidified molten steel inside the slab; and a
second heater 340 installed so as to be able to move forward and backward in a region
directly below the mold 160 and configured to heat an upper portion of the slab.
[0049] The stirring unit 320 is a device having at least one stirrer on an outside of
the mold 160 to improve quality of a slab and includes: a third stirrer 322 disposed in
proximity to the mold 160 and able to elevate in a drawing direction of the slab; and a
fourth stirrer 324 provided spaced apart below the third stirrer 322 and able to elevate in
the drawing direction of the slab. That is, the stirring unit 320 stirs at least any one of
molten steel accommodated in a molten state in the mold 160 and unsolidified molten steel
in the produced slab to perform grain refinement on a slab, thereby being capable of
improving quality of the slab.
[0050] As illustrated in FIG. 1, the third stirrer 322 is disposed spaced apart at a
predetermined distance from a side of the mold 160, and stirs molten steel accommodated

in the mold 160 during the casting. When the casting starts, the third stirrer 322 descends
by a predetermined distance along with a slab to stir unsolidified molten steel inside the
slab. That is, when molten steel is poured to the mold 160, the third stirrer 322 applies an
electromagnetic field to the molten steel from a side of the mold 160 to stir the molten steel,
and when pouring of the molten steel into the mold 160 is completed, the third stirrer 322
may stir unsolidified molten steel inside a slab while descending to a lower portion along
with the slab. An electromagnetic stirrer (EMS) may be used as the third stirrer 322. The
electromagnetic stirrer being able to be used as the third stirrer 322 typically has a low
frequency (Hz) band corresponding to a frequency enough to stir molten steel in a molten
state.
[0051] The fourth stirrer 324 is provided spaced apart at a predetermined distance
below the third stirrer 322, and elevates in a drawing direction of a slab to stir unsolidified
molten steel in the slab. A final electromagnetic stirrer (FEMS) may be used as the fourth
stirrer 324. The fourth stirrer 324 is disposed in a relatively lower portion compared to
the third stirrer 322, and it is preferable to use a stirring device having a higher frequency
(Hz) than the third stirrer 322 in order to stir molten steel existing inside a solidified region
in a lower portion of a slab (a lower portion from the center with respect to a longitudinal
direction of a slab) in which solidification has progressed to some extent.
[0052] Thus, the stirring unit 320 stirs solidified molten steel in the mold and
unsolidified molten steel in the slab, thereby being capable of enhancing the equiaxed
crystal ratio in slab and reducing segregation and porosity. Meanwhile, the present
invention does not limit a stirring region of a slab stirred by the third and fourth stirrers
322 and 324 and an elevating width of the stirrers, and various moving ranges may be
applicable according to casting conditions.

[0053] The second heater 340 is a device disposed outside of the mold 160 and
installed so as to be able to move forward and backward in a region directly below the
mold (a path in a drawing direction of a slab) to heat an upper portion of the cast slab (tail
portion). In this embodiment, a method according to induction heating (electromagnetic
heater, EMH) was employed. The second heater 340 indirectly heats the upper side of a
slab by using an electromagnetic field generated in an induction heating coil by power
supply, and is wound so as to surround the slab while being spaced apart at a
predetermined interval from four directional sides of the slab. Thus, the second heater 340
preferably uses an induction coil having a shape corresponding to a cross-section of the
slab, but not limited thereto, may be wound in various forms.
[0054] Meanwhile, a pusher 400 may be provided to the casting unit la so as to
transfer a slab to the solidification unit lb after casting of molten steel is completed.
[0055] The pusher 400 is a device disposed in a position facing the solidification
unit lb of sides of the casting unit la and pushing a side of a slab and separating the slab
from the drawing machine 200 to deliver the slab towards the solidification unit lb. A
device capable of reciprocally moving a predetermined distance may be used for the
pusher 400, and for example, a stepping motor, an actuator, a solenoid, or the like may be
used. As an example, when an actuator is used as the pusher 400, a piston reciprocally
moves while being inserted and ejected into/from a cylinder, thus being able to push the
slab toward the solidification unit lb and then return back to an original position. A device
delivering the slab of the casting unit la to the solidification unit lb is not limited to the
pusher 400 and may be a variety of devices.
[0056]
[0057] The solidification unit lb is a section receiving a slab so as to solidify the

slab cast from the above described casting unit la and includes: a support unit 500
disposed on at least any one side of the slab to support the slab; and a first quality
controller 600 provided on an outside of the slab to induce solidification of the slab. The
solidification unit lb receives the slab from a section spaced apart at a predetermined
distance from the casting unit 1a, completes solidification of the slab, and then transfers the
slab to a post-process (for example, forging or rolling).
[0058] The support unit 500 is provided so that the slab is stably positioned in the
solidification unit 1b and includes: a support block 520 disposed in contact with the bottom
of the slab; and a support frame 540 disposed surrounding a portion of a side of the slab.
However, the configuration of the support unit 500 is not limited thereto, but the slab may
be supported by a variety of devices and methods within the extent not interfering with the
movement of the first quality controller 600.
[0059] The supporting block 520 uses a block in a shape similar to the surface
plate 220 of the casting unit 1a. The support block 520 plays a role of supporting a lower
portion of the slab disposed in the solidification unit lb in a drawing direction, i.e. a
longitudinal direction.
[0060] The support frame 540 may be disposed spaced apart at a predetermined
distance from a side of the slab and surrounding a portion of a side of the slab so as to
suppress and prevent the slab disposed in the longitudinal direction from falling, as
illustrated in an enlarged view in FIG. 1.
[0061]
[0062] The first quality controller 600 as a device provided on an outside of a
slab and to ensure slab quality includes: a first stirrer 620 disposed in proximity to an
outside of the slab and able to elevate in a longitudinal direction of the slab; a second

stirrer 640 provided spaced apart below the first stirrer 620 and able to elevate in the
longitudinal direction of the slab; and a first heater 660 configured to heat an upper portion
of the slab. That is, since solidification of the slab which is naturally cooled is not
completed, the first quality controller 600 may be provided with a device the same as or
similar to the casting unit 1a to continue a treatment process for improving slab quality.
[0063] The first stirrer 620 as a device for stirring unsolidified molten steel in a
slab delivered to the solidification unit lb is disposed spaced apart at a predetermined
distance from the slab. The first stirrer 620 may be installed so as to be able to elevate in
such a way that the first stirrer 620 descends to be disposed on a side of the slab when the
slab is delivered to the solidification unit lb with the first stirrer 620 being disposed at the
same height as or a similar height to the third stirrer 322. The first stirrer 620 is disposed in
an upper portion outside of the slab. That is, the first stirrer 620 is disposed above the
center of the slab with respect to a longitudinal direction of the slab. An unsolidified region
in an upper portion of the slab, which is stirred by the first stirrer 620, is subjected to
relatively less progressed solidification than a lower portion of the slab, so that a large
amount of unsolidified molten steel is included in the slab compared to the lower portion
of the slab. Thus, an electromagnetic stirrer (EMS) similar to the third stirrer 322 may be
used.
[0064] Meanwhile, although the first stirrer 620 uses a device similar to the third
stirrer 322, the first and third stirrers 620 and 322 may be different in the size of a
frequency generated thereby or the operating time thereof from each other. That is, the
third stirrer 322 stirs molten steel in the mold 160 or molten steel in an initial slab
subjected to solidification, and thus uses a frequency less than about 1 Hz. The third stirrer
322 operates during the following processes: pouring of molten steel into the mold 160,

casting the molten steel into a slab, and transferring of the slab to the solidification unit lb.
In the case of the first stirrer 620, due to a characteristic of the slab transferred to the
solidification unit lb, the slab is not provided with the mold and forms a thicker solidified
shell compared to the slab cast in the casting unit. Therefore, the first stirrer 620 uses a
frequency of up to 5 Hz and operates until the casting of the slab is completed so that the
magnetic field of the first stirrer 620 passes through the thickened solidified shell to stir
unsolidified molten steel in the slab. However, solidification of a slab occurs in a wide
variety of forms according to casting situations and casting conditions, so that the third and
first stirrers 322 and 620 may use a frequency in a range of 0 to 5 Hz according to various
operation patterns. In addition, the first stirrer 620 disposed in the solidification unit lb in
FIG. 3D stirs unsolidified molten steel in the slab to equalize temperatures of unsolidified
molten steel in the slab during solidification of the slab in the solidification unit la, thus
being able to operate very efficiently in reducing pipe defects inside the slab in such a way
that the first heater 660 heats an upper side of the slab to prevent an upper portion of the
slab from being pre-solidified. Similarly, the third stirrer 322 disposed in the casting unit
la in FIG. 3F stirs unsolidified molten steel in the slab to equalize temperatures of
unsolidified molten steel in the slab during solidification of the slab in the casting unit la,
thus being able to operate very efficiently in reducing pipe defects inside the slab in such a
way that the second heater heats an upper side of the slab to prevent an upper portion of the
slab from being pre-solidified.
[0065] The second stirrer 640 is provided spaced apart at a predetermined
distance below the first stirrer 620 and installed so as to elevate in a longitudinal direction
of a slab to stir unsolidified molten steel in the slab. That is, the second stirrer 640 is
disposed below the center of the slab with respect to a longitudinal direction of the slab.

Although the second stirrer 640 may use a final electromagnetic stirrer (FEMS) similar to
the fourth stirrer 324 so as to stir unsolidified molten steel in a lower region outside of the
slab, the second and fourth stirrers 640 and 324 may be different in the size of a frequency
generated thereby or the operating time thereof from each other. That is, the fourth stirrer
322 uses a frequency of up to about 3 Hz so as to stir unsolidified molten steel in the slab
which is being solidified in the casting unit la. The fourth stirrer 324 operates before the
slab cast in the casting unit la is transferred to the solidification unit lb. In the case of the
second stirrer 640, due to a characteristic of the slab transferred to the solidification unit lb,
the slab forms a thicker solidified shell compared to the slab cast in the casting unit.
Therefore, the second stirrer 640 uses a frequency of up to 6 Hz and operates until the
casting of the slab is completed. However, solidification of a slab occurs in a wide variety
of forms according to casting situations and casting conditions, so that the fourth and
second stirrers 324 and 640 may use a frequency in a range of 0 to 6 Hz according to
various operation patterns.
[0066] Meanwhile, in the embodiment, although the first and second stirrers 620
and 640 are provided in plurality to respectively stir unsolidified molten steel in different
regions of the slab, an apparatus and a method for stirring unsolidified molten steel in the
slab in the solidification unit lb are not limited thereto. That is, the embodiment may be
modified to various methods and apparatus shapes in such a way that a single stirrer is
provided and a whole region from an upper portion to a lower portion of the slab may be
stirred while the frequency of the stirrer is being changed.
[0067] Thus, the first and second stirrers 620 and 640 stir molten steel until
solidification of the slab transferred to the solidification unit lb is completed, thus being
able to enhance the equiaxed crystal ratio in the slab and improve slab quality by reducing

segregation and porosity as in the stirring unit 320 of the casting unit la.
[0068] Meanwhile, in the case of the third and first stirrers 322 and 620 applied to
the present invention, in order to ensure a uniform stirring force in molten steel in the slab
according to significantly increased sizes compared to molds applied to existing
continuous casting machines, coils wound around the mold 160 or the slab were disposed
in the form of a circle to perform rotation-type stirring on unsolidified molten steel in the
mold or the slab.
[0069] The first heater 660 is a device installed so as to be able to move forward
and backward in a direct upper region of slab for heating an upper portion of the slab in an
outside of the slab and configured to heat an upper portion (tail portion) of the slab
transferred to the solidification unit lb. Since the first heater 660 has similar configuration
and effect as in the second heater 340, a detailed description thereof will not be repeated.
[0070] The above described casting installation 1 may include a transfer unit
which transfers the slab from the casting unit la to the solidification unit lb and/or from
the solidification unit lb to the outside of the solidification unit lb, i.e. a post-process.
[0071] The transfer unit 700 is a device disposed on one side of the solidification '
unit lb and formed so as to be able to move forward and backward toward the casting unit
or the solidification unit to transfer the slab. The transfer unit 700 includes: a tilting unit
720 for tilting the slab in contact with the slab in the casting unit la or transferring the slab
from the casting unit la to the.solidification unit lb; and a driving unit 740 controlling
operation of the tilting unit 720.
[0072] The tilting unit 720 is disposed on one side of the slab and transfers the
slab while being tilted or moved forward and backward by the driving unit, and the support
block 520 of the solidification unit lb is connected to transfer the slab. That is, the slab

may be transferred from the casting unit la to the solidification unit lb in such a way that
one side of the tilting unit 720 is connected to the support block 520 supporting the slab
and the slab is disposed on the support block 520. When the slab is transferred from the
solidification unit lb to the outside of the solidification unit, the tilting unit 720 is tilted
with the slab being in contact with one side of the tilting unit 720 and the slab may be
seated on the tilting unit disposed in the transferring direction. On a side in which the
tilting unit 720 contacts the slab, a roller 725 may be mounted to easily transfer the slab.
[0073] The driving unit 740 controls operation of the tilting unit 720, and may
allow the tilting unit 720 to move forward and backward so that the tilting unit 720
approaches or recedes from the casting unit la. In addition, the driving unit 740 allows the
tilting unit 720 to be tilted and communicate with a roller table 800 guiding the tilting unit
720 and the slab to a post-process. A device such as the pusher 400 of the casting unit la
capable of reciprocally moving a predetermined distance may be used for the driving unit
740, and for example, when an actuator is used, the tilting unit 720 may be connected to an
end of a piston so as to enable angle adjustment.
[0074] In this way, in this embodiment, although the method and device as
described above are used for the transfer unit 700 transferring the slab, the device and
operating method used for the transfer unit 700 are not limited thereto, and various devices
and methods capable of easily transferring the slab may be used when the slab is
transferred from the casting unit la to the solidification unit lb or from the solidification
unit lb to a post-process.
[0075]
[0076] Hereinafter, a casting method using the above-described casting
installation will be described.

[0077] Referring to FIG. 2, a casting method according to an embodiment of the
present invention includes: providing molten steel to prepare casting; casting the molten
steel in a casting unit allowing a passage through which the molten steel passes to be
opened or closed; and transferring a slab produced through the casting to a solidification
unit.
[0078] First, molten steel after refining is completed is accommodated in a ladle
120 and then transferred to the casting unit so as to start casting. The molten steel
transferred to the casting unit is supplied to the tundish 140 from the ladle 120, flotation of
inclusion is then performed in the tundish 140 for a period of time, and the molten steel is
then poured to the mold, thereby performing the process in the casting unit la (SI00). As
illustrated in FIG. 3, preparation of the casting is competed in a condition in which the
surface plate 220 is positioned in a mold to prevent molten steel poured to the mold 160
from being discharged to the outside (S120).
[0079] After the preparation of the cast is completed, as illustrated in FIG. 3B, as
the drawing machine 200 operates to lower the surface plate 220 down and a slab SI
connected to the surface plate 220 is drawn downwards to start the casting, slab is
produced (S140). Before the casting starts, the third stirrer 322 is operated to stir molten
steel in the mold. The slab is produced in a size of a maximum thickness of 800 mm, a
maximum width of 2000 mm, and cast at a casting rate of 0.3m per minute or less. By a
characteristic of an extremely thick steel material, the mold 160 in which a slab has an
increased thickness needs to be used so as to obtain a final product having an increased
thickness. A reason why the slab is cast at a low casting rate of 0.3 m per minute is that
suppressing occurrence of segregation to secure internal quality by casting at a slow
casting rate and securing a sufficient thickness of the solidified shell during casting are

required as a solidification rate of a slab for the extremely thick steel material is slow
unlike a general slab.
[0080] While the casting is in progress, the third. stirrer 322 continually stirs
molten steel in the mold and the fourth stirrer 324 continually stirs unsolidified molten
steel inside the slab so that solidification proceeds by characteristic of thick slab. Thus, the
third and fourth stirrers 322 and 324 may refine a structure of slab by continuously stirring
molten steel to enhance quality and equiaxed crystal ratio of slab.
[0081] When the casting is complete on the casting unit la (S160), the slab S1
located in the casting unit 1a is separated from the surface plate by the pusher 400 and
supported by the transfer unit 700 to move to the solidification unit (S200). When a
pushing force is delivered to the slab S1 by the pusher 400, the slab S1 may be transferred
to the solidification unit 1b in a state solidification of a surface is advanced to a degree of
no deformation. Meanwhile, the stirring unit 329 moving upper and lower portions in the
casting and solidifying slab returns to its original position so as not to interfere with
transfer of the slab S1.
[0082] After the slab is transferred to the solidification unit lb, a process of
finally completing solidification of the slab S1 proceeds in the solidification unit lb (S300).
That is, since the slab S1 is solidified in the solidification unit lb, a casting process may be
performed in the casting unit la. When solidification of the slab S1 starts, the first quality
controller 600 provided in the solidification unit lb descends or ascends to be disposed
spaced apart from an outside of slab. That is, as illustrated in FIG. 3, the first and second
stirrers 620 and 640 are disposed outside of the slab for stirring unsolidified molten steel
inside the slab S1 to operate until solidification of the slab S1 is completed.
[0083] In a process of solidifying the slab, the first heater 660 indirectly heats an

upper portion of the slab inside each of regions to solidifying the upper portion of slab
while heat is suppressed from being released from a side of the upper portion of the slab as
much as possible. This may suppress or prevent unsolidified region of an upper portion of
the slab from being pre-solidified by indirectly heating a side of an upper portion of the
slab to minimize a solidification shrinkage defect such as a pipe. Thus, yielding percentage
of slab is enhanced to improve yielding percentage of a final slab.
[0084] Thus, when solidification of the slab is completed in the solidified portion
lb, S340, as illustrated in FIG. 3E, the slab is tilted by the tilting unit 720 of the transfer
unit 700 and the tilting unit 720 of the transfer unit 700 is connected to the roller table 800
disposed in vicinity of the transfer unit 700 and the slab is transferred to a post-process
along the roller table 800.
[0085] Thus, the process of FIGS. 3A to 3F is not limited to a number of times
and may be repeated. As illustrated (b) in FIG. 2, after a process of the casting unit la is
completed, a process of the casting unit la is re-processed in the casting unit la and
produces another slab S2 to be able to be repeated until obtaining required quantity while
the slab Si is transferred to the solidification unit to perform a process of the casting unit
(slab solidification process).
[0086] When the process of the casting unit la no longer proceeds after repeating
the above described process, that is, the last slab Se is produced in the casting unit la after
the slab S2 in FIG. 3E is transferred to the solidification unit lb, the slab Se in the casting
unit la may finish solidification in the casting unit la without being transferred to the
solidification unit lb. That is, the slab Se finishes solidification by using the second quality
controller 300 provided in the casting unit la and then may be transferred to a post-process
(S360). The second heater 340 of the casting unit la indirectly heats an upper portion of

the slab Se to perform a role of the first heater 660 of the solidification unit lb. However,
the last produced slab Se may be transferred to a post-process after being transferred to the
solidification unit 1b and then completing a solidification process as similarly as the
previously produced slabs S1 and S2. Thus, a position of the final slab Se is not limited.
[0087] Hereinafter, effects of the present invention will be described in more
detail through experimental examples.
[0088] Table 1 shows the results of changes in slab thickness and yielding
percentage of a finally produced slab in a variety of process conditions for producing the
extremely thick steel material.

[0090] Herein, the slab thickness of the initial stage indicates the thickness of the
slab when an additional post-process is not performed on the slab of a completed cast. In
addition, the slab thickness of the middle stage indicates the thickness of the slab after a
forging process beating or pressing the slab and, the slab thickness of the final stage
indicates the thickness of the slab after a rolling process.
[0091] Each of the slabs (Comparative Example 1, Comparative Example 2,
Example) shown in Table 1 are slabs produced as a slab for the extremely thick steel
material after undergone a casting process and then at least any one of a forging or a rolling
process, and Table 1 may show following results as below.
[0092] [Comparative Example 1]
[0093] The slab in Comparative Example 1 is produced through an ingot process,

thus being able to be obtained by supplying molten steel to a mold and cooling the molten
steel. The slab produced as above has an initial thickness of about 1500 ram. Then, the slab
finally has a thickness of about 178 mm after undergone a forging and rolling process so as
to form a thickness for the extremely thick steel material. However, it may be confirmed
that a total yielding percentage has a low value of about 52%.
[0094] [Comparative Example 2]
[0095] The Slab in Comparative Example 2 is produced through a normal casting
installation, thus being able to be produced by continuously pouring and solidifying molten
steel supplied from a steelmaking plant to a mold.
[0096] The slab in Comparative Example 2 is produced through a normal casting
installation, thus being able to be produced by continuously pouring and solidifying molten
steel supplied from a steelmaking plant to a mold. The slab produced as above has very
high yielding percentage of about 95 %. However, in a generally used casting installation,
the slab is produced to have an initial thickness of about 450 mm, thus having a thickness
about 150 mm after a rolling process is completed. Thus, it may be confirmed that the slab
is limited to have a thickness of about 150 mm when used for the extremely thick steel
material.
[0097] [Example]
[0098] The slab in Example is produced through a casting installation according
to an embodiment of the present invention, thus being produced through the slab having a
maximum thickness of about 800 mm and a maximum width of about 2000 mm. Thus, the
slab in Example produced to have an initial thickness of about 800 mm and may be
confirmed to finally have a thickness of about 178 mm after undergone a forging and
rolling process. In addition, since the casting installation is separated into a casting unit

and a solidification unit and a process for preventing pre-solidification of an upper portion
of the slab is performed, the slab in Example is confirmed to have a yielding percentage of
about 89 %.
[0099] As such, the slab in Example has a yielding percentage significantly
enhanced by about 40 % when compared to the slab of Comparative Example 1 and a
thickness suitable for the extremely thick steel material when compared to the slab in
Comparative Example 2. That is, the slab produced by the installation in Example may
solve problems of a slab produced through an ingot casting and a conventional continuous
casting.
[00100] In addition, the extremely thick steel material produced according to the
embodiment was not observed to have a surface defect (for example, a corner crack)
identified by a naked eye and segregation generated inside the slab as macro quality
achieved equiaxed crystal ratio of 100 % by applying a molten steel stirrer to the slab.
Accordingly, it may be confirmed that the extremely thick steel material produced
according to the embodiment of the present invention is improved.
[00101] As described above, according to the embodiment of the present invention,
since a continuous casting installation is separated into the casting unit and the
solidification unit and the slab in which casting is completed in the casting unit is
transferred to the solidification unit and the slab in which solidification is completed in the
solidification unit is transferred to a post-process, the extremely thick steel material may be
easily produced and quality and yielding percentage of the slab finally produced may be
improved.
[00102] More specifically, since the slab produced in a casting unit is transferred
to the solidification unit and then solidification of the slab is completed through the first

quality controller and pre-solidification of an upper portion of the slab is suppressed or
prevented to reduce formation of pipe, quality of the slab may be enhanced. Therefore,
since cutting unsound region that is a problem of an ingot casting is not performed due to
improved slab quality, yielding percentage of the slab may be enhanced.
[00103] In addition, since the next slab may be cast in the casting unit while the
slab is transferred to the solidification unit and then solidified in the solidification unit, a
problem of a batch process such as a conventional continuous casting may be solved. Thus,
as a result, productivity of the slab may be increased. Further, the slab produced in a last
casting process is not transferred to the solidification unit and solidification of the slab may
be completed through the second quality controller provided in the casting unit. Thus,
process efficiency may be improved.
[00104] The present invention will now be described more fully with reference to
the accompanying drawings, in which exemplary embodiments of the invention are shown.
The present invention is limited not thereto and but by Claims. Moreover, various changes
and modifications within the scope not departing from the basic principles of the present
invention are possible to those skilled in the art of the present invention.

WHAT IS CLAIMED IS:
1. A easting installation comprising:
a casting unit defining a passage through which molten steel passes and for casting
the molten steel into a slab; and
a solidification unit comprising:
a support unit disposed spaced apart from the casting unit and receiving
the slab from the casting unit and disposed on at least any one place of sides of the
slab to support the slab; and
a first quality controller provided on an outside of the slab to induce
solidification of the slab.
2. The casting installation of claim 1, wherein the first quality controller comprises:
a first stirrer disposed in proximity to an outside of the slab and able to elevate in a
longitudinal direction of the slab;
a second stirrer provided spaced apart below the first stirrer and able to elevate in
the longitudinal direction of the slab; and
a first heater installed so as to be able to move forward and backward in a region
directly above the slab and configured to heat an upper portion of the slab.
3. The casting installation of claim 2, wherein the first stirrer has coils wound around
the slab and disposed in the form of a circle.
4. The casting installation of claim 1, wherein the casting unit comprises:

an accommodation unit having a space in which the molten steel is
accommodated;
a drawing machine drawing the slab from the accommodation unit to a lower
portion; and
a second quality controller provided on an outside of the passage.
5. The casting installation of claim 4, wherein the accommodation unit comprises a
mold configured to form the passage through which the molten steel supplied to a tundish
passes, and the mold is formed so that the slab has a thickness of 800 mm or less and a
width of 2000 mm or less.
6. The casting installation of claim 4, wherein the second quality controller
comprises:
a stirring unit comprising at least one stirrer disposed on an outside of the mold
and configured to stir at least any one of the molten steel and unsolidified molten steel
inside the slab; and
a second heater installed so as to be able to move forward and backward in a
region directly below the mold and configured to heat an upper portion of the slab.
7. The casting installation of claim 6, wherein the stirring unit comprises:
. a third stirrer disposed in proximity to the mold and able to elevate in a drawing
direction of the slab; and
a fourth stirrer provided spaced apart below the third stirrer and able to elevate in
the drawing direction of the slab.

8. The casting installation of claim 7, wherein the third stirrer has coils wound
around the mold or the slab and disposed in the form of a circle.
9. The casting installation of claim 1, wherein a pusher for separating the slab from
the drawing machine is provided to the casting unit and the pusher is installed so as to be
able to reciprocally move forward and backward toward the solidification unit.
10. The casting installation of claim 1, wherein a transfer unit transferring the slab
from the casting unit to the solidification unit or from the solidification unit to an outside
of the solidification unit is provided.
11. A casting method comprising:
providing molten steel to prepare casting;
casting the molten steel in a casting unit allowing a passage through which the
molten steel passes to be opened or closed;
transferring a slab produced through the casting to a solidification unit; and
transferring the slab to a post-process after solidification of the slab is completed.
12. The casting method of claim 11, wherein the casting of the molten steel is repeated
in the casting unit after the slab is transferred to the solidification unit.
13. The casting method of claim 12, wherein, when the casting of the molten steel is
repeated, the transferring the slab to the solidification unit is performed while the molten

steel is transferred to the casting unit so that preparing the casting is performed.
14. The casting method of claim 11, wherein when the casting of the molten steel is a
single casting, that is one time casting, the solidification of the slab is completed in the
casting unit or after the slab is transferred to the solidification unit.
15. The casting method of claim 11, wherein the molten steel is cast at a casting rate
0.3m per minute or less.