JP7531936B2 - Slab surface quenching system and process based on horizontal band of continuous caster - Google Patents

Description

The present invention relates to the field of metallurgy, and in particular to a slab surface hardening system and process based on a horizontal band of a continuous caster.

The hot delivery and hot charge process of continuous casting billet is an important production process that efficiently connects the steel-rolling interface of steel enterprises. Compared with the traditional process of "removing billet from production line → stacking and cooling → heating in heating furnace", this process has the advantages of significantly reducing energy consumption, simplifying the process flow, and improving production efficiency. However, when using the hot delivery and hot charge process to produce micro-alloy steel containing components such as Nb, Al, and V, after the billet enters the heating furnace and is heated, serious net-like crack defects (called "hot delivery cracks") will occur on its surface, causing serious quality defects on the surface of the rolled material.

Research has shown that the main reasons why hot delivery cracks often occur on the surface of continuous cast slabs of micro-alloy steel containing Nb, Al, V, etc., are as follows: Under the conventional continuous casting production process of micro-alloy steel and the configuration of the continuous casting-rolling steel production line, the surface temperature of the slab hot delivered and hot charged to the heating furnace often drops to 650-550°C, and the slab surface structure at this temperature has a two-phase structure of γ→α transformation. When the slab is placed in the heating furnace and heated, the difference in the size of the crystal grains of the newly formed austenite and the original austenite on the surface is large, and an obvious mixed crystal structure appears, greatly reducing the high-temperature plasticity of the slab surface structure. In addition, the micro-alloy carbonitrides precipitated in a chain shape along the original austenite grain boundaries during the continuous casting production process are pinned to the original austenite grain boundaries during the embrittlement heating process. The heating stress causes the slab surface to crack along the grain boundaries, forming mesh-like crack defects. Therefore, reconstructing the surface structure of the slab and dispersing and precipitating the carbonitrides is the key to eliminating crack defects caused by hot delivery on the surface of microalloy steel continuous casting slabs.

Researchers have proposed adding a cooling water tank or a quenching curved belt to the roller table from the rear of the continuous casting cutter to the heating furnace mouth, so as to rapidly cool the slab after ruler cutting and achieve the quenching effect on the slab surface. However, in actual continuous casting production, there is a limit to the continuous casting speed, and the surface temperature of the slab after cutting is often lowered to below 800°C when it enters the cooling water tank. In the slab surface structure at this temperature, the precipitation of micro-alloy carbonitrides such as Nb and Al has already been completed, and even if the slab surface is quenched at this temperature, the precipitation size and distribution of the carbonitrides cannot be changed. In addition, if the slab surface is quenched at this temperature, the surface structure has already begun to transform from austenite to ferrite, while the slab surface structure after quenching cannot recover the temperature and become austenitic again, and the highly plastic transformation of the structure cannot be realized.

Therefore, developing a continuous casting slab high-temperature quenching equipment and process that can improve the slab surface structure, disperse and precipitate carbonitrides, highly plasticize the high-temperature structure of the slab surface, and stably remove cracks caused by hot delivery on the slab surface in combination with the actual high-temperature solidification characteristics of micro-alloy steel and the continuous slab casting production process is of great significance for realizing high-quality, high-efficiency and green production of micro-alloy steel sheets, and is expected to become widespread in the future.

In view of the above, the present invention provides a slab surface hardening system and process based on a horizontal band of a continuous caster.

Specifically, the technical solutions include the following:

One aspect of the present invention is
Including a curved quenching band for quenching the surface of the slab;
The continuous casting machine includes a reduction curved zone, the quenching curved zone is located behind the reduction curved zone, and the surface temperature of the slab at the inlet of the quenching curved zone is 930°C or higher.
the quenching curved band includes a first spray frame and a second spray frame;
The first spray frame and the second spray frame are both provided in a plurality of rows, the plurality of rows of the first spray frames are provided in parallel on one side of the slab, the plurality of rows of the first spray frames harden the surface of the one side of the slab, the plurality of rows of the second spray frames are provided in parallel on the other side of the slab, the plurality of rows of the second spray frames harden the surface of the other side of the slab, the plurality of rows of the first spray frames and the plurality of rows of the second spray frames are provided opposite to each other,
the quenching curved band further comprises an inner arch structure and an outer arch structure, the first spray frame is disposed on the inner arch structure, and the second spray frame is disposed on the outer arch structure;
The first spray frame includes a first nozzle , and a plurality of the first nozzles are provided, and the plurality of first nozzles are evenly arranged in a width direction of the slab;
The second spray frame includes a second nozzle , the second nozzles being provided in plurality, and the second nozzles being evenly spaced in the width direction of the slab.

Furthermore, the first nozzle has a spray angle of 60 to 120° in the width direction of the slab, and an overlap width of spray water sprayed from two adjacent first nozzles in each row of the first spray frame in the width direction on the surface of the slab is 0 to 70 mm,
The slab surface hardening system based on the horizontal band of a continuous casting machine as described in claim 1, characterized in that the second nozzle has a spray angle of 60 to 120° in the width direction of the slab, and an overlap width in the width direction of the slab surface of spray water sprayed from two adjacent second nozzles in each row of the second spray frame is 0 to 70 mm.

the quenching curved zone further comprises a first casting roll and a second casting roll, each of which is provided in plurality, a plurality of the first casting rolls being provided on one side of the slab and a plurality of the first casting rolls being arranged in sequence in a drawing direction of the slab, a plurality of the second casting rolls being provided on the other side of the slab and a plurality of the second casting rolls being arranged in sequence in a drawing direction of the slab, and the first casting rolls and the second casting rolls being arranged in one-to-one correspondence;
the first nozzle is provided between two adjacent first casting rolls, and a boundary line of an injection angle of the first nozzle in a drawing direction of the slab is in contact with an outer wall surface of the adjacent first casting roll;
2. The slab surface hardening system based on the horizontal strip of a continuous casting machine according to claim 1, wherein the second nozzle is provided between two adjacent second casting rolls, and a boundary line of an injection angle of the second nozzle in a drawing direction of the slab is in contact with an outer wall surface of the adjacent second casting roll.

Furthermore, the vertical distance between the end of the first nozzle and the surface of the slab closer to the first nozzle is 90 to 200 mm;
The slab surface hardening system based on the horizontal band of a continuous casting machine according to claim 1, characterized in that the vertical distance between the end of the second nozzle and the surface of the slab closer to the second nozzle is 90 to 200 mm.

Furthermore, the first nozzles in two adjacent rows of the first spray frames are arranged in a staggered pattern, the interval between the first nozzles in the two adjacent rows of the first spray frames in the width direction of the slab is 50 mm or more, and the interval between the first nozzles in the two adjacent rows of the first spray frames in the width direction of the slab is half or less of the interval between two adjacent first nozzles in the first spray frames in each row,
The slab surface hardening system based on the horizontal band of a continuous casting machine as described in claim 1, characterized in that the second nozzles in two adjacent rows of the second spray frames are arranged in a staggered pattern, the spacing between the second nozzles in the two adjacent rows of the second spray frames in the width direction of the slab is 50 mm or more, and the spacing between the second nozzles in the two adjacent rows of the second spray frames in the width direction of the slab is half or less of the spacing between two adjacent second nozzles in the second spray frames in each row.

The spray system further includes a first water supply pipe and a second water supply pipe, the first water supply pipe being connected to a plurality of rows of the first spray frames, the plurality of rows of the first spray frames being arranged in parallel, and the second water supply pipe being connected to a plurality of rows of the second spray frames, the plurality of rows of the second spray frames being arranged in parallel;
further including a first shutoff valve, a second shutoff valve, a first regulating valve, a second regulating valve, a first flow meter, a second flow meter, a first pressure gauge, and a second pressure gauge;
2. The slab surface hardening system based on the horizontal band of a continuous casting machine as claimed in claim 1, wherein the first shut-off valve, the first regulating valve, the first flow meter and the first pressure gauge are provided in the first water supply pipe before being connected to the first rows of spray frames, and the second shut-off valve, the second regulating valve, the second flow meter and the second pressure gauge are provided in the second water supply pipe before being connected to the second rows of spray frames.

Another aspect of the present invention is a method for producing a
quenching the slab entering the above-mentioned continuous caster horizontal zone based slab surface quenching system through the reduction curve zone;
The continuous casting machine horizontal band based slab surface quenching system includes a quenching curved band for quenching the surface of the slab,
A slab surface quenching process based on a continuous caster horizontal zone is disclosed, in which the temperature within a range of 0-10 mm below the skin of the surface of the slab drops from 930°C or higher to 600°C or lower when quenching is performed in the quenching curved zone.

Furthermore, the quenching time of the surface of the slab is 60 seconds or more, and the depth of the quenched layer on the surface of the slab is 10 mm or more,
The average rate of temperature decrease within a range of 0 to 10 mm depth below the surface of the slab is faster than 5° C./s.

Further, the quenching curved band includes a first spray frame and a second spray frame, the first spray frames are arranged in a plurality of rows, the plurality of rows of the first spray frames are arranged in parallel on one side of the slab, the second spray frames are arranged in a plurality of rows, the plurality of rows of the second spray frames are arranged in parallel on the other side of the slab, and the plurality of rows of the first spray frames and the plurality of rows of the second spray frames are arranged opposite to each other;
The slab surface quenching system based on the horizontal band of the continuous casting machine includes a first water supply pipe and a second water supply pipe, the first water supply pipe is connected to a plurality of rows of the first spray frames, and the second water supply pipe is connected to a plurality of rows of the second spray frames;
The slab surface hardening system based on the horizontal belt of the continuous casting machine determines the flow rate of the first water supply pipe and the flow rate of the second water supply pipe based on the steel type of the slab and the casting speed of the slab, and adjusts the flow rate of the spray water sprayed from the first spray frame of the multiple rows and the second spray frame of the multiple rows;
The slab surface hardening system based on the horizontal belt of the continuous casting machine controls the ratio of the flow rate of the first water supply pipe to the flow rate of the second water supply pipe to be 0.5 or less.

The beneficial effects of the technical solutions according to the embodiments of the present invention include at least the following:

In the present invention, the quenching process is carried out on the surface of the slab using a quenching curved band provided after the reduction curved band, so that the temperature in the range of 0-10 mm below the skin of the upper and lower surfaces of the micro-alloy steel continuous casting slab containing Nb, Al, V, etc. that has been subjected to online quenching is rapidly reduced from 930°C or higher to 600°C or lower, achieving the purpose of dispersed precipitation of carbonitrides and structural transformation from austenite to ferrite or bainite, fundamentally improving the plasticity of the cast slab surface structure, and reliably preventing the occurrence of cracks due to hot delivery of the micro-alloy steel slab. The present invention stably maintains the cracking effect due to hot delivery of the cast slab, which is of great significance for realizing high quality, high efficiency and green production of micro-alloy steel sheets, and is expected to be widely used in the future.

In order to more clearly describe the technical solutions of the embodiments of the present invention, the following will briefly describe the drawings necessary for the description of the embodiments. Obviously, the drawings in the following description are only some embodiments of the present invention, and those skilled in the art can obtain other drawings based on these drawings without requiring creative efforts.
FIG. 2 is a front view of the quenching curved band of the slab surface quenching system based on the horizontal band of the continuous casting machine according to the present invention. FIG. 2 is a partial side view of a quenching curved band of a slab surface quenching system based on a horizontal band of a continuous caster according to the present invention. FIG. 2 is a diagram showing the layout principle of the water supply piping of the slab surface hardening system based on the horizontal belt of the continuous casting machine according to the present invention. FIG. 2 is a metallographic diagram of a slab surface hardening system based on a horizontal band of a continuous casting machine according to the present invention. FIG. 2 is a diagram showing the profile of carbonitride precipitation by the slab surface hardening system based on the horizontal band of a continuous caster according to the present invention.

The technical solutions of the embodiments of the present invention will be described below clearly and completely with reference to the drawings of the embodiments of the present invention. Obviously, the described embodiments are only a part of the embodiments of the present invention, and not all of the embodiments. All other embodiments that a person skilled in the art can obtain based on the embodiments of the present invention without creative efforts are within the patentable scope of the present invention.

Before describing the embodiments of the present invention in more detail, it should be noted that the directional nouns used in the examples of the present invention, such as "top", "bottom" and "side", are not intended to limit the scope of the present invention with respect to the orientation shown in FIG. 1.

To make the technical solutions and advantages of the present invention clearer, the embodiments of the present invention will be described in more detail below with reference to the drawings.

As shown in Figures 1 to 3, this embodiment discloses a slab surface hardening system based on a horizontal band of a continuous casting machine, the slab surface hardening system includes a hardening curved band for hardening the surface of the slab 1, the continuous casting machine includes a reduction curved band, the hardening curved band is located behind the reduction curved band, and the surface temperature of the slab 1 at the entrance of the hardening curved band is 930°C or higher.

Furthermore, in this embodiment, the reduction curved zone usually means a light reduction zone, the quenching curved zone means a horizontal curved zone located after the light reduction curved zone, and the slab 1 passes through the light reduction zone and the quenching curved zone in sequence, provided that the surface temperature of the slab 1 at the entrance to the quenching curved zone is 930°C or higher. In the case where a heavy reduction zone is also provided after the light reduction zone in the continuous casting machine, the quenching curved zone means a horizontal curved zone located after the heavy reduction zone, and the slab 1 passes through the light reduction zone, the heavy reduction zone, and the quenching curved zone in sequence.

Furthermore, in this embodiment, the quenching curved zone is a specific horizontal curved zone among the horizontal curved zones of the continuous casting machine, and the quenching curved zone is provided after the reduction curved zone, taking into consideration that the solidification end point of the slab 1 is within the reduction curved zone, and the surface temperature of the slab 1 at the exit of the reduction curved zone is usually higher than 930°C.

In addition, it is understood that aluminum nitride or vanadium, niobium, and boron carbonitrides are precipitated at the grain boundaries of austenite during quenching, and the precipitation "nose" temperature range is about 600°C to 900°C, and the cast slab surface structure is reconstructed and the carbonitrides are dispersed and precipitated, which is the key to eliminating the cracks caused by hot delivery on the surface of the micro-alloyed steel continuous casting slab. In this embodiment, the surface temperature of the slab 1 at the entrance of the quenching curved band is 930°C or higher, and the quenching process is performed on the surface of the slab 1 by the quenching curved band, so that the temperature in the range of 0 to 10 mm below the skin of the upper and lower surfaces of the micro-alloyed steel continuous casting slab 1 containing Nb, Al, V, etc. that has been subjected to online quenching is quickly reduced from 930°C or higher to 600°C or lower, thereby achieving the purpose of dispersed precipitation of carbonitrides and structural transformation from austenite to ferrite or bainite, fundamentally improving the plasticity of the cast slab surface structure, and reliably avoiding the occurrence of cracks caused by hot delivery of the micro-alloyed steel slab. This invention stably maintains the cracking effect caused by hot delivery of cast slabs, and is of great significance for realizing high-quality, high-efficiency and green production of micro-alloy steel sheets, and is expected to become widespread in the future.

As shown in Fig. 1, the quenching curved band includes a first spray frame 2 and a second spray frame 4, each of which is arranged in a plurality of rows, the plurality of rows of the first spray frames 2 are arranged in parallel on one side of the slab 1, the plurality of rows of the first spray frames 2 quench the surface on one side of the slab 1, the plurality of rows of the second spray frames 4 are arranged in parallel on the other side of the slab 1, the plurality of rows of the second spray frames 4 quench the surface on the other side of the slab 1, and the plurality of rows of the first spray frames 2 and the plurality of rows of the second spray frames 4 are arranged opposite to each other. The quenching curved band further includes an inner arch structure and an outer arch structure, the first spray frame 2 is arranged on the inner arch structure, and the second spray frame 4 is arranged on the outer arch structure. The first spray frame 2 includes a first nozzle 6, and the plurality of first nozzles 6 are arranged, and the plurality of first nozzles 6 are arranged evenly in the width direction of the slab 1. The second spray frame 4 includes a second nozzle 7 , and a plurality of the second nozzles 7 are provided, and the plurality of second nozzles 7 are evenly arranged in the width direction of the slab 1 .

Furthermore, in this embodiment, the quenching curved band is based on a horizontal curved band structure of a conventional continuous casting machine, with the existing inner arch spray frame and outer arch spray frame changed to a first spray frame 2 and a second spray frame 4, respectively, and the existing nozzle changed to a high-flow nozzle , which corresponds to the first nozzle 6 and the second nozzle 7 of the present invention.

Furthermore, as shown in Fig. 1, it is understood that the slab 1 in the horizontal curved belt is in a state of being transported horizontally, the slab 1 is a long slab, the cross section of the slab 1 is rectangular, as shown in Fig. 1, _L1 is the width of the slab 1, and _L1 represents the width direction of the slab 1, and the arrow in Fig. 2 represents the drawing direction of the slab 1. A plurality of rows of first spray frames 2 are arranged in parallel on the upper part of the slab 1 (see Figs. 1 and 3), which quenches the upper surface of the slab 1, and a plurality of rows of second spray frames 4 are arranged in parallel on the lower part of the slab 1 (see Figs. 1 and 3), which quenches the lower surface of the slab 1.

Furthermore, in this embodiment, the quenching curved band is a modification based on the conventional horizontal curved band, which solves the problem of evaporation and drainage during quenching of high-temperature cast pieces.

Furthermore, as shown in FIGS. 1 and 2, the vertical axis of the first nozzle 6 is perpendicular to the upper surface of the slab 1 , and the vertical axis of the second nozzle 7 is perpendicular to the lower surface of the slab 1 .

Furthermore, as shown in FIG. 1, multiple rows of first spray frames 2 are evenly arranged in the withdrawal direction of the slab 1, the first spray frames 2 include a spray frame water supply pipe 21 and a plurality of spray tubes 22, the spray frame water supply pipe 21 is connected to the first water supply pipe B, the multiple spray tubes 22 are evenly arranged on the spray frame water supply pipe 21 along the width direction of the slab 1, the spray tubes 22 are arranged in one-to-one correspondence with the first nozzles 6, the spray tubes 22 are arranged coaxially with the first nozzles 6, the first nozzles 6 are arranged at the end of the spray tube 22 close to the slab 1, and the multiple first nozzles 6 are evenly arranged in the width direction of the slab 1.

Furthermore, multiple rows of second spray frames 4 are evenly arranged in the withdrawal direction of the slab 1, the second spray frames 4 include a spray frame water supply pipe 41 and a plurality of spray pipes 42, the spray frame water supply pipe 41 is connected to the second water supply pipe C, the multiple spray pipes 42 are evenly arranged in the spray frame water supply pipe 41 along the width direction of the slab 1, the spray pipes 42 and the second nozzle 7 are arranged in a one-to-one correspondence, the spray pipe 42 is arranged coaxially with the second nozzle 7, the second nozzle 7 is arranged at the end of the spray pipe 42 close to the slab 1, and the multiple second nozzles 7 are evenly arranged in the width direction of the slab 1.

As shown in Figure 1, the first nozzles 6 have a spray angle of 60 to 120° in the width direction of the slab 1, and in the first spray frames 2 in each row, the overlap width in the width direction of the surface of the slab 1 of the spray water sprayed from two adjacent first nozzles 6 is 0 to 70 mm, and the second nozzles 7 have a spray angle of 60 to 120° in the width direction of the slab 1, and in the second spray frames 4 in each row, the overlap width in the width direction of the surface of the slab 1 of the spray water sprayed from two adjacent second nozzles 7 is 0 to 70 mm.

1, θ ₁ indicates the nozzle injection angle in the width direction of the slab 1, and L ₄ indicates the overlap width in the width direction of the surface of the slab 1 of the spray water injected from two adjacent nozzles in each row of spray frames. In this embodiment, the injection angle θ ₁ of the first nozzle 6 in the width direction of the slab 1 is 60 to 120°, and the injection angle θ ₁ of the second nozzle 7 in the width direction of the slab 1 is 60 to 120°.

Furthermore, the first nozzle 6 and the second nozzle 7 may be fan-shaped or rectangular pure water or aerosol nozzles . In this embodiment, the first nozzle 6 is selected in consideration of the flow rate at a water pressure of 0.6 MPa being 12 to 25 L/min, and the first nozzle 6 has a spray angle θ ₁ in the width direction of the slab 1 of 60 to 120°. The second nozzle 7 is selected in consideration of the flow rate at a water pressure of 0.6 MPa being 25 to 60 L/min, and the second nozzle 7 has a spray angle θ ₁ in the width direction of the slab 1 in the range of 60 to 120°. The spray angle θ ₁ is determined such that the overlap width L ₄ in the width direction of the surface of the slab 1 of the spray water sprayed from two adjacent first nozzles 6 is 0 to 70 mm, and the overlap width L ₄ in the width direction of the surface of the slab 1 of the spray water sprayed from two adjacent second nozzles 7 is 0 to 70 mm.

2, the quenching curved zone further includes a first casting roll 17 and a second casting roll, each of which is provided in plurality, the first casting rolls 17 being provided on one side of the slab 1 and arranged in sequence in the direction of drawing the slab 1, and the second casting rolls being provided on the other side of the slab 1 and arranged in sequence in the direction of drawing the slab 1, with the first casting rolls 17 and the second casting rolls being provided in one-to-one correspondence. The first nozzle 6 is provided between two adjacent first casting rolls 17, with the boundary line of the injection angle of the first nozzle 6 in the direction of drawing the slab 1 abutting on the outer wall surface of the adjacent first casting roll 17, and the second nozzle 7 is provided between two adjacent second casting rolls, with the boundary line of the injection angle of the second nozzle 7 in the direction of drawing the slab 1 abutting on the outer wall surface of the adjacent second casting roll.

Furthermore, although the second casting roll is not shown in FIG. 2, it is understood that the first casting roll 17 is provided above the slab 1 and abuts against the upper surface of the slab 1, and the second casting roll is provided below the slab 1 and abuts against the lower surface of the slab 1.

Further, as shown in Fig. 2, in this embodiment, the first nozzle 6 is provided between two adjacent first casting rolls 17, and the second nozzle 7 is provided between two adjacent second casting rolls, referring to the arrangement of the first nozzle 6. In Fig. 2, θ ₂ indicates the spray angle of the nozzle in the drawing direction of the slab 1. In this embodiment, as shown in Fig. 2, the spray angle θ ₂ has two boundary lines, and the distance L ₆ between the two intersection points formed by the two boundary lines of the spray angle θ ₂ and the surface of the slab 1 is the width that the spray water sprayed from the nozzle covers in the drawing direction of the surface of the slab 1. As can be seen from Fig. 2, both the first casting roll 17 and the second casting roll (not shown) are cylindrical, and the extension directions of the axes of the first casting roll 17 and the second casting roll are parallel to the width direction of the slab 1. The two boundary lines of the first nozzle 6 having the injection angle θ ₂ abut on the outer wall surfaces of two adjacent first casting rolls 17, and the two boundary lines of the second nozzle 7 having the injection angle θ ₂ abut on the outer wall surfaces of two adjacent second casting rolls.

Furthermore, when the first nozzle 6 or the second nozzle 7 is a rectangular nozzle , the spray angle θ ₂ is determined so that the spray water from the first nozzle 6 or the second nozzle 7 covers as wide a surface of the slab 1 as possible along the drawing direction of the slab 1 while ensuring that the spray water does not spray onto the first casting roll 17 or the second casting roll.

As shown in Figures 1 and 2, the vertical distance between the end of the first nozzle 6 and the surface of the slab 1 closer to the first nozzle 6 is 90 to 200 mm, and the vertical distance between the end of the second nozzle 7 and the surface of the slab 1 closer to the second nozzle 7 is 90 to 200 mm.

2 and 1, _L5 indicates the vertical distance between the end of the nozzle and the surface of the slab 1. In this embodiment, the vertical distance _L5 between the end of the first nozzle 6 and the upper surface of the slab 1 is 90 to 200 mm, and the vertical distance L5 between the end of the second nozzle 7 and the lower surface of the slab ₁ is 90 to 200 mm.

As shown in Fig. 1, the first nozzles 6 in two adjacent rows of the first spray frames 2 are arranged in a staggered manner, the interval between the first nozzles 6 in the width direction of the slab 1 in the two adjacent rows of the first spray frames 2 is 50 mm or more, and the interval between the first nozzles 6 in the width direction of the slab 1 in the two adjacent rows of the first spray frames 2 is half or less of the interval between two adjacent first nozzles 6 in each row of the first spray frames 2. The second nozzles 7 in two adjacent rows of the second spray frames 4 are arranged in a staggered manner, the interval between the second nozzles 7 in the width direction of the slab 1 in the two adjacent rows of the second spray frames 4 is 50 mm or more, and the interval between the second nozzles 7 in the width direction of the slab 1 in the two adjacent rows of the second spray frames 4 is half or less of the interval between two adjacent second nozzles 7 in each row of the second spray frames 4.

1, the number of first nozzles 6 in the multiple rows of first spray frames 2 is the same, and the first nozzles 6 in two adjacent rows of first spray frames 2 are arranged in a staggered manner. The number of second nozzles 7 in the multiple rows of second spray frames 4 is the same, and the second nozzles 7 in two adjacent rows of second spray frames 4 are arranged in a staggered manner.

1, _L3 indicates the interval between two adjacent nozzles in each row of spray frames, and _L2 indicates the interval between nozzles in two adjacent rows of spray frames in the width direction of the slab 1. In this embodiment, the range of the distance L2 between the first nozzles 6 in the first spray frames 2 in the two adjacent rows in the width direction of the slab ₁ is 50 mm or more and is half or less of the distance _L3 between the two adjacent first nozzles 6 in the first spray frames 2 in each row. The range of the distance _L2 between the second nozzles 7 in the second spray frames 4 in the two adjacent rows in the width direction of the slab 1 is 50 mm or more and is half or less of the distance _L3 between the two adjacent second nozzles 7 in the second spray frames 4 in each row.

As shown in FIG. 3, the slab surface hardening system based on the horizontal belt of a continuous casting machine includes a first water supply pipe B and a second water supply pipe C, the first water supply pipe B is connected to a plurality of rows of first spray frames 2, the plurality of rows of first spray frames 2 are arranged in parallel, and the second water supply pipe C is connected to a plurality of rows of second spray frames 4, the plurality of rows of second spray frames 4 are arranged in parallel. The slab surface hardening system based on the horizontal belt of the continuous casting machine further includes a first shutoff valve 9, a second shutoff valve 10, a first regulating valve 11, a second regulating valve 12, a first flow meter 13, a second flow meter 14, a first pressure gauge 15 and a second pressure gauge 16, the first shutoff valve 9, the first regulating valve 11, the first flow meter 13 and the first pressure gauge 15 are provided in the first water supply pipe B before being connected to the first spray frame 2 of the multiple rows, and the second shutoff valve 10, the second regulating valve 12, the second flow meter 14 and the second pressure gauge 16 are provided in the second water supply pipe C before being connected to the second spray frame 4 of the multiple rows.

Furthermore, in this embodiment, the slab surface quenching system based on the horizontal belt of the continuous casting machine further includes a main water supply pipe A, in which a main shutoff valve 8 is provided, and the first water supply pipe B and the second water supply pipe C are both branched off from the main water supply pipe A. The first water supply pipe B is sequentially provided with a first shutoff valve 9, a first flow meter 13, a first adjustment valve 11, and a first pressure gauge 15, and the first flow meter 13 and the first adjustment valve 11 are electrically connected, the first adjustment valve 11 is an air pressure adjustment valve, and the first adjustment valve 11 adjusts its own opening degree based on feedback information from the first flow meter 13. A second shutoff valve 10, a second flow meter 14, a second adjustment valve 12, and a second pressure gauge 16 are sequentially provided on the second water supply pipe C, the second flow meter 14 and the second adjustment valve 12 are electrically connected, the second adjustment valve 12 is an air pressure adjustment valve, and the second adjustment valve 12 adjusts its own opening degree based on feedback information from the second flow meter 14.

This embodiment also discloses a slab surface quenching process based on the horizontal band of a continuous casting machine, which quenches the slab 1 that passes through a reduction curved band and enters the above-mentioned slab surface quenching system based on the horizontal band of a continuous casting machine. The slab surface quenching system based on the horizontal band of a continuous casting machine includes a quenching curved band that quenches the surface of the slab 1, and when quenching is performed in the quenching curved band, the temperature within a range of 0 to 10 mm below the skin of the surface of the slab 1 drops from 930°C or higher to 600°C or lower.

Furthermore, the quenching medium for the upper and lower surfaces of the slab 1 is cooling water, and the aerosol or pure water spray nozzles strongly cool and quench the surface of the slab 1.

In addition, the slab surface quenching process based on the horizontal belt of the continuous casting machine must meet the following main technical features: (1) The quenching time of the surface of the slab 1 is not less than 60 s. (2) The depth of the quenched layer on the surface of the slab 1 is not less than 10 mm. (3) The average temperature drop rate within the range of 0-10 mm depth below the surface of the slab 1 is greater than 5°C/s. (4) The quenching end temperature of the upper and lower surfaces of the slab 1 is 350-500°C. (5) The ratio of the flow rate of the first water supply pipe B to the flow rate of the second water supply pipe C is not more than 0.5.

Depending on the type of slab 1 and the transport speed of the slab 1, the amount of water sprayed onto the upper and lower surfaces of the slab 1 is determined so as to satisfy the above requirements (1) to (5) and to avoid "bulging" and "warping" deformation during hardening of the slab 1.

Furthermore, the quenching curved belt includes a first spray frame 2 and a second spray frame 4, the first spray frames 2 are arranged in multiple rows, the multiple rows of the first spray frames 2 are arranged in parallel on one side of the slab 1, the second spray frames 4 are arranged in multiple rows, the multiple rows of the second spray frames 4 are arranged in parallel on the other side of the slab 1, and the multiple rows of the first spray frames 2 and the multiple rows of the second spray frames 4 are arranged opposite to each other. The slab surface quenching system based on the continuous casting machine horizontal belt includes a first water supply pipe B and a second water supply pipe C, the first water supply pipe B is connected to the multiple rows of the first spray frames 2, and the second water supply pipe C is connected to the multiple rows of the second spray frames 4.

Furthermore, the slab surface hardening system based on the horizontal band of the continuous casting machine determines the flow rate of the first water supply pipe B and the flow rate of the second water supply pipe C based on the steel type of the slab 1 and the casting speed of the slab 1, and adjusts the flow rate of the spray water sprayed from the multiple rows of first spray frames 2 and the multiple rows of second spray frames 4. The slab surface hardening system based on the horizontal band of the continuous casting machine controls the ratio of the flow rate of the first water supply pipe B to the flow rate of the second water supply pipe C to 0.5 or less.

Furthermore, in this embodiment, the main water supply pipe A is made of stainless steel or galvanized steel pipe and laid from the water supply source to the secondary cooling water valve chamber of the continuous casting machine or near the continuous casting machine, the water supply pressure is 1.0 MPa or more, and a manual shutoff valve 8 is arranged. The water supply capacity of the main water supply pipe A must be sufficient for the surface quenching of the slab at the maximum casting speed of the continuous casting of the microalloy steel of the slab continuous casting machine to meet the requirements of the above processes (2) to (5). Specifically, in the mainstream conventional wide and thick slab continuous casting machine with a casting speed of 1.3 m/min or less, the water supply capacity of the main water supply pipe A should be 250 m ³ /h/flow or more, and in the normal slab continuous casting machine with a casting speed of 2.0 m/min or less, the water supply capacity of the main water supply pipe A should be 350 m ³ /h/flow or more.

In addition, in this embodiment, the slab surface quenching system based on the horizontal band of the continuous casting machine further includes a quenching water amount dynamic control system, and the control logic of the quenching water amount for the upper and lower surfaces of the slab 1 is as follows: The quenching water amount dynamic control system calls a quenching water amount meter (see Table 1) that matches the steel type based on the steel type and casting speed being produced by the continuous casting machine, and dynamically controls the opening degree of the first adjustment valve 11 of the first water supply pipe B and the opening degree of the second adjustment valve 12 of the second water supply pipe C in real time independently according to the upper surface quenching water amount of the slab 1 and the lower surface quenching water amount of the slab 1 preset by the appropriate quenching water amount meter according to the current casting speed of the continuous casting machine, thereby dynamically controlling the quenching water amount for the upper and lower surfaces of the slab 1.

Table 1. Quenching water volume on the top and bottom surfaces of Nb-containing microalloy steel slabs at a certain steelworks

According to the slab surface quenching system and process based on the continuous casting machine horizontal band of this embodiment, online continuous quenching of the slab is possible regardless of the length of the slab. In this embodiment, the quenching temperature of the slab 1 is high, so that the dispersed precipitation of carbonitrides and the tissue structure transition of the surface layer of the slab 1 are realized, the plasticity of the surface layer structure of the slab is fundamentally improved, the occurrence of cracks due to hot delivery of the micro-alloy steel slab is reliably avoided, and the cracking effect due to hot delivery of the slab is stably maintained. In this embodiment, the quenching water amount of the upper and lower surfaces of the slab is adjusted to ensure that the depth of the quenching layer of the surface layer of the slab is controlled as needed. In this embodiment, the conventional problem that excessive deformation during quenching of cut-to-size slabs has a negative impact on production is solved. In this embodiment, the quenching curved band is located in the horizontal curved band, so that the problem of steam discharge and drainage during quenching of high-temperature slabs is solved. In this embodiment, by quenching the tissue about 10 mm deep beneath the skin on the top and bottom surfaces of slab 1, most of the heat in slab 1 is retained, and the temperature near the slab cutter recovers to about 830°C, without affecting normal production such as slab cutting. In this embodiment, the slab is quenched while it is being produced, so there is no increase in the time the slab spends in the process or on the rollers.

In this example, a slab surface hardening system and process based on the horizontal band of a continuous casting machine will be explained using a steelworks as an example.

In this embodiment, the slab 1 has a continuous casting cross section of 2100 mm x 250 mm, and L ₁ is 2100 mm. In such a cross section, the casting speed of the mainstream continuous casting is 0.9 to 1.1 m/min, and the maximum casting speed is 1.2 m/min. In the continuous casting machine of this steelworks, 14 curved zones are provided, and the solidification end point of the slab 1 is in the 13th curved zone under the condition of the maximum casting speed of 1.2 m/min, and in this embodiment, the quenching curved zone is the 14th curved zone, which is an improvement of the conventional 14th curved zone. The 14th curved zone has a horizontal length of 2.1 m in the drawing direction, and seven pairs of the first casting roll 17 and the second casting roll are provided.

When the steelworks produces a micro-alloy steel slab 1 with a cross section of 2100 mm x 250 mm under continuous casting speed conditions of 0.8 to 1.2 m/min, the actual measured temperature of the surface of slab 1 at the entrance of the 14th curved band (i.e., the exit of the 13th curved band) is in the range of 935 to 980°C. Based on the actual temperature distribution on the surface of this slab 1, the 14th curved band is improved to become a quenching curved band, and pure water is used as the cooling medium for quenching the upper and lower surfaces of slab 1.

When the quenching water amount shown in Table 1 was applied to the upper and lower surfaces of slab 1 in the quenching curved zone, under the casting speed conditions of 0.8 to 1.2 m/min (under special conditions such as changing the tundish in continuous casting or forecasting steel leakage, the casting speed of slab 1 in the 14th zone deviates slightly from this casting speed range, and under special conditions, this quenching process is not performed when producing the slab), the quenching duration of the upper and lower surfaces of slab 1 reached 105 to 158 s, the temperature of the upper and lower surfaces of the continuously cast slab 1 after quenching was 360 to 400°C, and no obvious deformation was observed. In addition, calculations using a three-dimensional solidification heat transfer model of slab 1 showed that with the quenching water amount and quenching duration of 105 to 158 seconds listed in Table 1, the depth of the quenched layer on the top and bottom surfaces of slab 1 reached 12 to 15 mm, and the quenching cooling rate within the range of 0 to 10 mm below the skin on the top and bottom surfaces met the requirement of >5°C/s.

As a result of actual use, the crystal grains at 10 mm below the surface of the quenched micro-alloy steel slab containing Nb and Al were clearly refined (see Figure 4), micro-alloy carbonitrides were dispersed and precipitated (see Figure 5), and the slab 1 was transported directly from the rollers to the heating furnace for heating, with no cracks occurring due to hot delivery.

In this embodiment, the slab surface quenching system based on the horizontal band of the continuous casting machine consists of a main water supply pipe A, a first water supply pipe B, a second water supply pipe C, a curved quenching band, and a dynamic quenching water volume control system.

3, the main water supply pipe A is a DN250 galvanized steel pipe branched off from the secondary cooling main pipe and laid to the secondary cooling water valve chamber of the continuous casting machine, the water pressure of the main water supply pipe A is 1.08 MPa, and after leaving the secondary cooling main pipe, it is connected to a manual shutoff valve 8, and then communicates with the secondary cooling water valve chamber and is connected to the first water supply pipe B and the second water supply pipe C. The water supply capacity of the main water supply pipe A is about 250 m ³ /h.

As shown in FIG. 3, the first water supply pipe B and the second water supply pipe C are steel pipes made of DN125 and DN200 stainless steel, respectively. One end of the first water supply pipe B and one end of the second water supply pipe C are both connected to the main water supply pipe A, the first water supply pipe B is connected to the first shutoff valve 9, the first flow meter 13, the first regulating valve 11 and the first pressure gauge 15, the second water supply pipe C is connected to the second shutoff valve 10, the second flow meter 14, the second regulating valve 12 and the second pressure gauge 16, and the first water supply pipe B and the second water supply pipe C are laid up to the vicinity of the strand of the quenching curved belt (i.e., the existing 14th curved belt) and supply water to the multiple rows of the first spray frames 2 and the multiple rows of the second spray frames 4, respectively. The water supply capacities of the first water supply pipe B and the second water supply pipe C are 70 m ³ /h and 180 m ³ /h, respectively, and the ratio of the water supply capacities of the first water supply pipe B and the second water supply pipe C is 1:2.57.

In this embodiment, based on the horizontal band structure of a conventional continuous casting machine, the existing inner arch spray frame and outer arch spray frame are changed to a first spray frame 2 and a second spray frame 4, respectively, and the existing nozzles are changed to a first nozzle 6 and a second nozzle 7 with high flow rate. The first spray frames 2 and the second spray frames 4 are both arranged in seven rows in the drawing direction, and the seven rows of the first spray frames 2 are fixed to the inner arch frame structure of the quenching curved band (the existing 14th curved band), and the seven rows of the second spray frames 4 are fixed to the outer arch frame structure of the quenching curved band (the existing 14th curved band).
1 and 2, in this embodiment, the vertical distance _L5 between the end of the first nozzle 6 and the upper surface of the slab 1 is 150 mm, and the vertical distance _L5 between the end of the second nozzle 7 and the lower surface of the slab 1 is 150 mm. Since the maximum width _L1 of the slab 1 is 2100 mm, the first spray frame 2 is provided with seven first nozzles 6, the seven first nozzles 6 are arranged at equal intervals, and the interval _L3 between two adjacent first nozzles 6 is 307.5 mm. The second spray frame 4 is provided with seven second nozzles 7, the seven second nozzles 7 are arranged at equal intervals, and the interval _L3 between two adjacent second nozzles 7 is 307.5 mm. The first nozzles 6 in two adjacent rows of the first spray frames 2 are arranged in a staggered manner in the width direction of the slab 1, and the distance L2 between the first nozzles 6 in the two adjacent rows of the first spray frames 2 in the width direction of the slab ₁ is 90 mm, and the second nozzles 7 in two adjacent rows of the second spray frames 4 are arranged in a staggered manner in the width direction of the slab 1, and the distance _L2 between the second nozzles 7 in the two adjacent rows of the second spray frames 4 in the width direction of the slab 1 is 90 mm.

As shown in Fig. 1, in this embodiment, a plurality of rows of first spray frames 2 are arranged in parallel to the first water supply pipe B, and a plurality of rows of second spray frames 4 are arranged in parallel to the second water supply pipe C. The first spray frame 2 and the second spray frame 4 each include a spray frame water supply pipe and a plurality of spray pipes, the spray frame water supply pipe 21 of the first spray frame 2 is connected to the first water supply pipe B, and the plurality of spray pipes 22 are evenly distributed on the spray frame water supply pipe 21 along the width direction of the slab 1, the spray pipe 22 is arranged coaxially with the first nozzle 6, the first nozzle 6 with a large flow rate is screwed to the end of the spray pipe 22 of the first spray frame 2, and the plurality of first nozzles 6 are evenly arranged in the width direction of the slab 1. The spray frame water supply pipe 41 of the second spray frame 4 is connected to the second water supply pipe C, and a plurality of spray pipes 42 are evenly distributed in the spray frame water supply pipe 41 along the width direction of the slab 1, the spray pipe 42 is arranged coaxially with the second nozzle 7, the high-flow second nozzle 7 is screwed to the end of the spray pipe 42 of the second spray frame 4, and the plurality of second nozzles 7 are evenly arranged in the width direction of the slab 1.

As shown in Figures 1 and 2, the first nozzle 6 is a rectangular pure water nozzle , and the flow rate at 0.6 MPa water pressure reaches 23 L/min, the first nozzle 6 has a spray angle θ ₁ of 100° in the width direction of the slab 1, and a spray angle θ ₂ of 50° in the drawing direction. The second nozzle 7 is also a rectangular pure water nozzle , and the flow rate at 0.6 MPa water pressure reaches 60 L/min, the second nozzle 7 has a spray angle θ ₁ of 100° in the width direction of the slab 1, and a spray angle θ ₂ of 50° in the drawing direction. The spray water sprayed from the first nozzle 6 onto the upper surface of the slab 1 is in contact with the outer wall surface of the first casting roll 17, and the cover width L ₆ of the upper surface of the slab 1 in the drawing direction is 140 mm (see Figure 2). The spray water sprayed from the second nozzle 7 onto the lower surface of the slab 1 is in contact with the outer wall surface of the second casting roll, and the cover width L ₆ of the lower surface of the slab 1 in the drawing direction is 140 mm. In each row of first spray frames 2, the overlap width _L4 in the width direction of the upper surface of the slab 1 of spray water sprayed from two adjacent first nozzles 6 is 50 mm, and in each row of second spray frames ₄ , the overlap width L4 in the width direction of the lower surface of the slab 1 of spray water sprayed from two adjacent second nozzles 7 is 50 mm.

In this embodiment, the control logic of the quenching water amount for the upper and lower surfaces of slab 1 by the dynamic quenching water amount control system is as follows: The dynamic quenching water amount control system calls a quenching water amount meter (see Table 1) that matches the steel type based on the steel type and casting speed being produced by the continuous casting machine, and dynamically adjusts the amount of quenching water for the upper and lower surfaces of slab 1 by independently and dynamically controlling the opening degree of the first adjustment valve 11 and the second adjustment valve 12 of the first water supply pipe B and the second water supply pipe in real time according to the quenching water amount for the upper surface of slab 1 and the quenching water amount for the lower surface of slab 1 preset by the quenching water amount meter according to the current casting speed of the continuous casting machine.

In the present invention, the terms "first" and "second" are for descriptive purposes only and do not denote or imply relative importance. Unless expressly limited otherwise, the term "plurality" means two or more.

Those skilled in the art can easily conceive of other embodiments of the present invention by practicing the present invention disclosed in the specification and herein. The present invention is intended to cover all modifications, uses or adaptations of the present invention, which modifications, uses or adaptations follow the general principles of the present invention and include common knowledge or customary technical means in the art that are not disclosed in the present invention. The specification and examples are to be considered as illustrative.

The above is merely a preferred embodiment of the present invention and is not intended to limit the present invention. All modifications, equivalent substitutions, improvements, etc. made without departing from the spirit and principles of the present invention are intended to be included in the patent scope of the present invention.

Reference Signs List 1 Slab 2 First spray frame 4 Second spray frame 21, 41 Spray frame water supply pipe 22, 42 Spray pipe 6 First nozzle
7 Second nozzle
DESCRIPTION OF THE PREFERRED EMBODIMENTS 1. Field of the Invention The present invention relates to a casting _roll . A casting roll having _a casting method and a casting method for casting a casting slab. 2. The casting roll having a casting method _and a _casting method for casting a casting slab. _3. The casting roll having a casting method and a casting method for casting a casting slab. _4. The casting roll having a casting method and a _casting method for casting a casting slab. These drawings and textual description are not intended to limit the scope of the inventive concept in any way, but rather to explain the inventive concept to those skilled in the art with reference to specific embodiments.

Claims (6)

A slab surface hardening system based on a continuous caster horizontal band, comprising:
A curved hardening band for hardening the surface of the slab (1),
The continuous casting machine includes a reduction curved zone, the quench curved zone is located behind the reduction curved zone, and the surface temperature of the slab (1) at the inlet of the quench curved zone is 930° C. or higher;
The quenching curved band includes a first spray frame (2) and a second spray frame (4);
The first spray frames (2) and the second spray frames (4) are both provided in multiple rows, the multiple rows of the first spray frames (2) are provided in parallel on one side of the slab (1), the multiple rows of the first spray frames (2) harden the surface on one side of the slab (1), the multiple rows of the second spray frames (4) are provided in parallel on the other side of the slab (1), the multiple rows of the second spray frames (4) harden the surface on the other side of the slab (1), and the multiple rows of the first spray frames (2) and the multiple rows of the second spray frames (4) are provided opposite each other;
The quenching curved band further includes an inner arch structure and an outer arch structure, the first spray frame (2) is disposed on the inner arch structure, and the second spray frame (4) is disposed on the outer arch structure;
The first spray frame (2) includes a first nozzle (6), and a plurality of the first nozzles (6) are provided, and the plurality of first nozzles (6) are evenly arranged in the width direction of the slab (1);
The second spray frame (4) includes a second nozzle (7), and a plurality of the second nozzles (7) are provided, and the plurality of second nozzles (7) are evenly arranged in the width direction of the slab (1) ;
The first nozzle (6) has a flow rate of 12 to 25 L/min at a water pressure of 0.6 MPa, a spray angle in the width direction of the slab (1) is 60 to 120°, and an overlap width in the width direction of the surface of the slab (1) of spray water sprayed from two adjacent first nozzles (6) in each row of the first spray frame (2) is 0 to 70 mm,
The second nozzle (7) has a flow rate of 25 to 60 L/min at a water pressure of 0.6 MPa, a spray angle in the width direction of the slab (1) of 60 to 120°, and an overlap width in the width direction of the surface of the slab (1) of spray water sprayed from two adjacent second nozzles (7) in each row of the second spray frame (4) is 0 to 70 mm . the quenching curved zone further comprises a first casting roll (17) and a second casting roll, each of which is provided in plurality, the first casting rolls (17) being provided on one side of the slab (1) and the first casting rolls (17) being arranged in sequence in a drawing direction of the slab (1), the second casting rolls being provided on the other side of the slab (1) and the second casting rolls being arranged in sequence in a drawing direction of the slab (1), and the first casting rolls (17) and the second casting rolls being arranged in one-to-one correspondence;
the first nozzle (6) is provided between two adjacent first casting rolls (17), and a boundary line of a jet angle of the first nozzle (6) in a drawing direction of the slab (1) is in contact with an outer wall surface of the adjacent first casting roll (17);
2. The slab surface hardening system based on the horizontal band of a continuous casting machine according to claim 1, wherein the second nozzle (7) is provided between two adjacent second casting rolls, and a boundary line of an injection angle of the second nozzle (7) in a drawing direction of the slab (1) is in contact with an outer wall surface of the adjacent second casting roll. the vertical distance between the end of the first nozzle (6) and the surface of the slab (1) closer to the first nozzle (6) is between 90 and 200 mm;
The slab surface hardening system based on the horizontal band of a continuous casting machine according to claim 1, characterized in that the vertical distance between the end of the second nozzle (7) and the surface of the slab (1) closer to the second nozzle (7) is 90 to 200 mm. the first nozzles (6) in two adjacent rows of the first spray frames (2) are arranged in a staggered pattern, the interval between the first nozzles (6) in the two adjacent rows of the first spray frames (2) in the width direction of the slab (1) is 50 mm or more, and the interval between the first nozzles (6) in the two adjacent rows of the first spray frames (2) in the width direction of the slab (1) is half or less of the interval between two adjacent first nozzles (6) in the first spray frames (2) in each row;
The slab surface hardening system based on the horizontal band of a continuous casting machine, as described in claim 1, characterized in that the second nozzles (7) in two adjacent rows of the second spray frames (4) are arranged in a staggered pattern, the spacing between the second nozzles (7) in the two adjacent rows of the second spray frames (4) in the width direction of the slab (1) is 50 mm or more, and the spacing between the second nozzles (7) in the two adjacent rows of the second spray frames (4) in the width direction of the slab (1) is half or less of the spacing between two adjacent second nozzles (7) in the second spray frames (4) in each row. The system includes a first water supply pipe (B) and a second water supply pipe (C), the first water supply pipe (B) is connected to a plurality of rows of the first spray frames (2), and the plurality of rows of the first spray frames (2) are arranged in parallel, the second water supply pipe (C) is connected to a plurality of rows of the second spray frames (4), and the plurality of rows of the second spray frames (4) are arranged in parallel,
further comprising a first shutoff valve (9), a second shutoff valve (10), a first regulating valve (11), a second regulating valve (12), a first flow meter (13), a second flow meter (14), a first pressure gauge (15), and a second pressure gauge (16);
2. The slab surface hardening system based on the horizontal band of a continuous casting machine according to claim 1, characterized in that the first shut-off valve (9), the first regulating valve (11), the first flow meter (13) and the first pressure gauge (15) are provided in the first water supply pipe (B) before being connected to the first rows of spray frames (2), and the second shut-off valve (10), the second regulating valve (12), the second flow meter (14) and the second pressure gauge (16) are provided in the second water supply pipe (C) before being connected to the second rows of spray frames (4). A slab surface hardening process based on a continuous caster horizontal band, comprising:
The method includes a step of quenching a slab (1) entering the slab surface quenching system based on the horizontal band of a continuous caster according to any one of claims 1 to 5 through a reduction curved band,
The slab surface hardening system based on the horizontal band of the continuous casting machine includes a curved hardening band for hardening the surface of the slab (1),
The surface quenching time of the slab (1) is 60 s or more,
The depth of the hardened layer on the surface of the slab (1) is 10 mm or more,
The average rate of temperature decrease within a range of 0 to 10 mm below the surface of the slab (1) is faster than 5° C./s;
The quenching end temperature of the upper and lower surfaces of the slab (1) is 350 to 500°C.
When quenching is performed in the quenching curved zone, the temperature in the range of 0 to 10 mm below the surface of the slab (1) drops from 930°C or higher to 600°C or lower ,
The slab surface hardening system based on the horizontal belt of the continuous casting machine includes a first water supply pipe (B) and a second water supply pipe (C), the first water supply pipe (B) is connected to a plurality of rows of the first spray frames (2), and the second water supply pipe (C) is connected to a plurality of rows of the second spray frames (4);
The slab surface hardening system based on the horizontal belt of the continuous casting machine determines the flow rate of the first water supply pipe (B) and the flow rate of the second water supply pipe (C) based on the steel type of the slab (1) and the casting speed of the slab (1), and adjusts the flow rate of the spray water sprayed from the multiple rows of the first spray frames (2) and the multiple rows of the second spray frames (4);
A slab surface hardening system based on the horizontal belt of a continuous casting machine, characterized in that the ratio of the flow rate of the first water supply pipe (B) to the flow rate of the second water supply pipe (C) is controlled to be 0.5 or less .