WO2019184731A1

WO2019184731A1 - Method for controlling structure of solidified cast ingot in continuous casting process and control device thereof

Info

Publication number: WO2019184731A1
Application number: PCT/CN2019/078326
Authority: WO
Inventors: 乌力平; 沈昶; 孙彪; 汪国才; 陆强
Original assignee: 马鞍山钢铁股份有限公司
Priority date: 2018-03-29
Filing date: 2019-03-15
Publication date: 2019-10-03
Also published as: EP3750649A4; CN108672668A; EP3750649A1; JP2021516621A; JP7111828B2

Abstract

A method for controlling the structure of a solidified cast ingot in a continuous casting process comprises: arranging a high-intensity cooling region (210) and a heating and slow-cooling region (230) in a space between a water drain port of a crystallizer and a solidification end point; performing high-intensity cooling on a continuously cast ingot (100) in the high-intensity cooling region; and then performing heating and slow-cooling on the continuously cast ingot (100) in the heating and slow-cooling region, wherein a cooling intensity of the heating and slow-cooling is less than a cooling intensity of air-based cooling. A device for employing heating and slow-cooling to control the structure of a solidified cast ingot is further disclosed, comprising a high-intensity cooling region and a heating and slow-cooling region arranged in a lengthwise direction of a continuously cast ingot at a lower portion of a continuous casting crystallizer, wherein the high-intensity cooling region is used to spray water to a surface of the cast ingot so as to perform cooling, and the heating and slow-cooling region is used to heat the surface of the cast ingot. In the method and device, a continuously cast ingot is firstly cooled in the high-intensity cooling region, and then undergoes heating and slow-cooling in the heating and slow-cooling region, thereby reducing spacing and gaps among columnar crystals, increasing efficiency of space-filling of near-surface columnar crystals on a cast ingot, and improving quality of the cast ingot.

Description

Method for controlling solidification structure of casting blank in continuous casting process and control device thereof

Technical field

The invention relates to the technical field of metallurgical continuous casting, and more particularly to a method for controlling the solidification structure of a slab during continuous casting and a control device thereof.

Background technique

In the modern steel continuous casting production technology, the structure and defects of the slab structure have seriously affected the quality of the slab. Due to the cooling mode in the traditional continuous casting technology, the performance of the slab structure on the castings and parts during the solidification process of the molten steel Adaptability is often insufficient, and the lack of regulation and degree makes the controllability of the solidification structure not good, and can not meet the increasing performance of materials, especially the specific individual requirements. For example, in some cases, excessive growth of columnar crystals makes the center segregation severe; in other cases, improper cooling causes grain and grain boundaries to be coarse; for example, columnar crystals that preferentially grow in the late stage of solidification cannot be controlled in the slab The center meets to form a “bridge”. The molten steel in the liquid phase is separated by the “solidified crystal bridge”. The molten steel in the lower part of the crystal bridge cannot be replenished by the upper metal to form loose or shrinkage holes, accompanied by central segregation and uneven composition. And other related issues. In order to solve the above problems, low-temperature casting technology, electromagnetic stirring technology and coagulation end soft reduction or casting and rolling technology have been formed in this aspect for a long time, but the solidification structure of the surface layer, subsurface layer and core of the slab remains not ideal.

A method for producing high carbon chromium bearing steel by double slow cooling process (publication number: CN101412183A; publication date: 2009.04.22), which is slowly cooled by the high temperature of the casting blank through the slow cooling pit of the casting blank The hydrogen content and stress of the slab are then placed in a slow hood to further release hydrogen and stress in the slab. The production method of high-carbon chromium bearing steel by two slow cooling can ensure the low-quality and non-white-point crack defects of the rolled material. However, it is worth noting that the slow cooling treatment of the cast slab in the prior art is often performed on the solidified slab, and it is difficult to effectively reduce the columnar crystal spacing and gap, especially in the near-surface columnar crystal of the slab. density.

Summary of the invention

1. The technical problem to be solved by the invention

The object of the present invention is to overcome the problem that the solidification structure of the surface layer, the subsurface layer and the core of the prior art is still not satisfactory, and to provide a method and a control device for controlling the solidification structure of the casting blank in the continuous casting process,

The invention provides a method for controlling the solidification structure of a slab during continuous casting, and a super-cooling zone and a heating slow-cooling zone are arranged in a section from the nozzle water nozzle to the end of the solidification end point, and the continuous casting slab is first in the super-cool zone. Super-cooling, and then heating and cooling in the heating and cooling zone can reduce the columnar crystal spacing and gap, increase the density of the near-layer columnar crystal of the slab, and reduce the occurrence of internal cracks;

The utility model provides a device for controlling the solidification structure of a slab based on heating and slow cooling. The lower part of the continuous casting mold is provided with a super-strong cooling zone and a heating slow cooling zone along the length direction of the continuous casting slab, and the super-cooling zone is used for Water spray cooling is provided on the surface of the slab, and the heating slow cooling zone is used to provide heat heating to the surface of the slab, which can reduce the columnar crystal spacing and gap, increase the density of the near columnar columnar crystal of the slab, and reduce the occurrence of internal cracks.

2. Technical solutions

In order to achieve the above object, the technical solution provided by the present invention is:

The invention discloses a method for controlling the solidification structure of a slab in a continuous casting process, wherein a super-strong cooling zone and a heating slow-cooling zone are arranged in a section from the nozzle water nozzle to the end of the solidification end point, and the continuous casting slab is first in the super-strong cooling zone. The super cooling is performed, and then the heating and cooling in the heating slow cooling zone is performed, wherein the cooling intensity of the heating slow cooling is less than the cooling intensity of the air cooling.

Preferably, a weak cooling zone is further disposed between the super-strong cooling zone and the heating slow cooling zone, and the weak cooling zone has a cooling intensity less than that of the super-cooling.

Preferably, the super-cooling zone water flow density is Q L/m ^{2 and the} weak cooling zone water flow density is q L/m ² , Q ≥ 2q.

Preferably, the super-cooling starting point of the super-strong cooling zone is located at the crystallizer sewer, and the length of the super-cooling zone is greater than 12% L, wherein L is the total cooling length, and the total cooling length is from the crystallizer sewer to the solidification end point.

Preferably, the distance between the heating slow cooling starting point of the heating slow cooling zone and the mold crystallizer water outlet is greater than 40% L, where L is the total cooling length.

Preferably, the water flow density in the super-cooling zone of the round billet continuous casting billet is ≥ 465 L/m ² , or the water flow density in the super-cooling zone of the rectangular billet continuous casting billet is ≥ 490 L/m ² , or the super-cooling of the thick-plate continuous casting billet The water flow density in the area is ≥255L/m ² .

Preferably, the surface of the slab is heated in the heating slow cooling zone, and the heat energy value of the heating is greater than 5 kW/m ² .

Preferably, the heating slow cooling end of the heating slow cooling zone is located before the solidification end point.

The invention relates to a device for controlling the solidification structure of a slab based on heating and slow cooling. The lower part of the continuous casting mold is provided with a super-strong cooling zone and a heating slow cooling zone along the length direction of the continuous casting slab, and the super-cooling zone is used for Water spray cooling is provided to the surface of the slab, and the heating slow cooling zone is used to provide heat to the surface of the slab.

Preferably, the surface of the continuous casting slab of the heating slow cooling zone is provided with an electromagnetic heating coil or a heating cover, wherein the heating cover is a steam heating cover or a flammable gas heating cover or a reflective heat insulation self-heating cover.

Preferably, the front portion of the heating slow cooling zone is provided with a weak cooling zone.

3. Beneficial effects

Compared with the prior art, the technical solution provided by the invention has the following remarkable effects:

(1) A method for controlling the solidification structure of a slab in a continuous casting process according to the present invention, wherein a super-cooling zone and a heating slow-cooling zone are arranged in a section from the nozzle water nozzle to the end of the solidification end point, and the continuous casting slab is first super Super-cooling in the strong cooling zone can effectively reduce the primary dendrite spacing and gap, increase the density of columnar crystals in the slab, reduce the columnar crystal loosening, and then heat the slow cooling zone to reduce the slab. Temperature gradient reduces the temperature difference between the surface and the inside of the slab, inhibits the growth of columnar crystals, and avoids the occurrence of internal cracks in the slab; thereby reducing the columnar crystal spacing and gap, and improving the solidification structure of the subsurface and core of the slab , increasing the density of the columnar crystals in the near surface layer of the slab, and reducing the occurrence of internal cracks;

(2) A method for controlling the solidification structure of a slab during continuous casting, the super-cooling starting point of the super-cooling zone is located at the nozzle of the crystallizer, and the length of the super-cooling zone is greater than 12% of the total cooling length If the cooling length is too short, sufficient dense columnar crystals and as thick a shell thickness as possible are not formed, which is disadvantageous for implementing the desired weak cooling control in the late solidification stage;

(3) A method for controlling the solidification structure of a slab during continuous casting in the present invention, wherein a weak cooling zone is provided between the super-cooling zone and the heating slow-cooling zone, and the cooling intensity of the weak cooling zone is less than that of the super-cooling cooling The strength, so as to ensure that the weak cooling zone has a sufficient range to ensure a good transition between the super-cooling zone and the heating and cooling zone during the continuous casting process, avoiding the direct transition of the continuous casting billet from the super-cooling zone to the heating slow-cooling zone, thereby avoiding Causes the surface temperature to rise too much, thereby reducing the internal cracks that are prone to occur in the solidified section;

(4) A method for controlling the solidification structure of a slab during continuous casting, wherein the distance between the heating slow cooling zone of the heating slow cooling zone and the crystallizer water outlet is greater than 40% of the total cooling length, and the heating is slow The end point of the heating ring of the zone is located before the solidification end point, that is, the range of the heating slow cooling zone from 40% after the total cooling length to the end of the solidification end point, thereby ensuring sufficient weakness between the super-strong cooling zone and the heating slow cooling zone. The cooling zone avoids the sudden temperature rise of the surface of the slab, and can reduce the internal cracks in the solidified section;

(5) A device for controlling the solidification structure of a slab based on heating and slow cooling according to the present invention, wherein a lower portion of the continuous casting mold is provided with a super-strong cooling zone and a heating slow-cooling zone along the length direction of the continuous casting slab, super-cooling The zone is used for providing water spray cooling to the surface of the slab, and the heating slow cooling zone is used for providing heat heating to the surface of the slab, reducing the columnar crystal spacing and gap, increasing the density of the near columnar columnar crystal of the slab, and reducing internal cracks. Produced to achieve the purpose of obtaining the solidification structure of the slab corresponding to the performance requirements of different final products.

DRAWINGS

1 is a schematic structural view of an apparatus for controlling a solidification structure of a slab based on heating and slow cooling according to the present invention;

Figure 2 is a heating and cooling zone of the present invention is an electromagnetic heating coil;

3 is a schematic view showing the microstructure of the slab of the embodiment 4;

4 is a schematic view showing the morphology of the microstructure of the slab of Comparative Example 1.

The reference numerals in the drawings indicate:

100, continuous casting billet; 110, unsolidified molten steel; 120, solidified shell;

210, super strong cold zone; 220, weak cooling zone; 230, heating slow cooling zone;

300, continuous casting mold;

410, columnar crystal region; 420, equiaxed crystal region; 430, loose pores.

detailed description

In order to further understand the contents of the present invention, the present invention will be described in detail with reference to the accompanying drawings and embodiments.

The structures, the proportions, the sizes, and the like of the drawings are only used to clarify the contents disclosed in the specification for understanding and reading by those skilled in the art, and are not intended to limit the conditions that can be implemented by the present invention. Without technical significance, the modification of any structure, the change of the proportional relationship or the adjustment of the size should still fall within the technology disclosed by the present invention without affecting the effects and the achievable objectives of the present invention. The content can be covered. In the meantime, the terms "upper", "lower", "left", "right", "intermediate", etc., as used in this specification, are merely for convenience of description, and are not intended to limit the scope of implementation. Changes or adjustments in relative relationships are considered to be within the scope of the invention, without departing from the scope of the invention.

As shown in FIG. 1 to FIG. 3, a device for controlling the solidification structure of a slab based on heating and slow cooling, the lower portion of the continuous casting mold 300 is provided with a super-strong cooling zone 210 along the longitudinal direction of the continuous casting slab 100. And the heating slow cooling zone 230, the exterior of the continuous casting blank 100 is a solidified shell 120, the inside of the solidified shell 120 is unsolidified molten steel 110, and the super-cooling zone 210 is used to provide water spray cooling to the surface of the solidified shell 120. That is, a nozzle is arranged in the super-cooling zone 210, and the nozzle is used for water-cooling cooling on the surface of the slab, and the heating slow-cooling zone 230 is used for supplying heat to the surface of the slab, thereby heating and tempering the surface of the slab. As shown in FIG. 2, an electromagnetic heating coil 231 is disposed on the surface of the continuous casting blank 100 of the heating slow cooling zone 230.

Alternatively, as shown in FIG. 3, the surface of the continuous casting blank 100 of the heating slow cooling zone 230 is provided with a heating cover 231, wherein the heating cover 231 is a steam heating cover or a combustible gas heating cover or a reflective heat insulation self-heating cover.

As shown in FIG. 3, the front portion of the heating slow cooling zone 230 is provided with a weak cooling zone 220, that is, the weak cooling zone 220 is disposed between the super-strong cooling zone 210 and the heating slow cooling zone 230. A nozzle is provided in the weak cooling zone 220 for performing water spray cooling on the surface of the slab. It is worth noting that the water spray cooling can also be water vapor mixed cooling.

The invention discloses a method for controlling the solidification structure of a slab during continuous casting, in which a super cooling, a weak cooling and a heating slow cooling measure are sequentially applied to a slab in a certain section of the casting direction in a continuous process of molten steel. Thereby, the secondary surface layer and the core solidification structure of the slab are improved, and the total energy release amount of the entire continuous casting process is ensured. The detailed description is: in the section from the lower nozzle of the continuous casting mold 300 to the end of the solidification end point, a super-strong cooling zone 210 and a heating slow cooling zone 230 are provided, and the continuous casting blank 100 is firstly cooled in the super-strong cooling zone 210, and then The heating slow cooling zone 230 performs heating and slow cooling, wherein the cooling intensity of the heating slow cooling is less than the cooling intensity of the air cooling; the cooling intensity of the super cooling is greater than the cooling intensity of the air cooling.

That is, the super-cooling starting point of the super-strong cooling zone 210 is located at the lower nozzle of the continuous casting mold 300, and the length of the super-strong cooling zone 210 is greater than 12% L, wherein L is the total cooling length, wherein the total cooling length is from the crystallizer sewer The distance to the end of solidification, i.e., the super-cooling zone 210, is extended from the spout of the continuous casting mold 300 in the casting direction to a total cooling length of greater than 12%. This is because the length of the super-cold zone 210 is less than 12% of the total cooling length, so that the section of the super-cold zone 210 is too short, so that the continuous casting blank 100 cannot form a sufficiently dense columnar crystal and as thick as possible. It is not conducive to the implementation of the desired weak cooling control in the late stage of solidification. The average cooling intensity of the super-cooling zone 210 is much larger than that of the existing continuous casting technology. This is because the amount of water in the early stage cooling is small, so that the cooling intensity is too low, so that the amount of heat released in the early stage of the slab is small, and the ideal cooling cannot be formed quickly. Thickness and density of the shell; therefore, it is necessary to strengthen the pre-cooling of the billet so that the total heat of the billet is released as much as possible in the early stage, so that the surface of the billet cannot quickly form the shell of the desired thickness and density. Therefore, the total heat of the slab is released as much as possible in the early stage, and the different types of slabs have super cooling strength, and the cooling strength can be expressed by the water flow density, and is different by Q L/m ² .

(1) The super-cooling zone 210 of the round billet continuous casting billet 100 has a water flow density Q ₁ ≥ 465 L/m ² ;

(2) The super-cooling zone 210 of the rectangular billet continuous casting billet 100 has a water flow density Q ₂ ≥ 490 L/m ² ;

(3) The super-cooling zone 210 of the thick slab continuous casting blank 100 has a water flow density Q ₃ ≥ 255 L/m ² ; and the thickness of the slab continuous casting is required to be not less than 200 mm;

The continuous casting blank 100 starts from the continuous casting mold 300, and the super cooling is applied thereto, which can effectively reduce the primary dendrite spacing and gap, increase the density of the columnar crystals in the casting blank, and reduce the columnar crystal looseness.

A weak cooling zone 220 is further disposed between the super-cooling zone 210 and the heating slow cooling zone 230 of the embodiment, and the cooling intensity of the weak cooling zone 220 is less than the cooling intensity of the super-cooling. After super-cooling, the cooling strength of the slab transitions to the weak cooling zone 220, and then passes through the weak cooling zone 220 and then transitions to the heating slow cooling zone 230, wherein the weak cooling zone 220 adopts the conventional cooling intensity of continuous casting. It is worth noting that the cooling intensity of the weak cooling zone 220 is q ₁ L/m ² and the super cooling intensity Q L/m ² is Q ≥ 2q ₁ . The cooling intensity of the different types of slab weak cooling zone 220 is different, and it is worth noting that the cooling intensity of the weak cooling zone 220 is substantially the same as the conventional cooling intensity during the continuous casting process, and the cooling intensity can be expressed by the water flow density. , specific classification description:

(1) For round billet continuous casting, the cooling strength (water flow density) of the region is required to be ≥ 155 L/m ² ;

(2) For rectangular billet continuous casting, the cooling strength (water flow density) of this area is ≥245L/m ² ;

(2) For slab continuous casting, the cooling strength (water flow density) of this area is ≥85L/m ² . The slab is first cooled by the super-cooling zone 210, and then transitioned through the weak cooling zone 220, and then enters the heating chill zone 230 for heating and tempering, which may reduce the temperature transition difference and reduce the temperature gradient in the slab. The temperature difference between the surface of the slab and the inside is reduced, and the growth of the columnar crystal is suppressed.

The distance between the heating slow cooling zone of the heating slow cooling zone 230 of the present embodiment and the water inlet of the continuous casting mold 300 is greater than 40% of the total cooling length, and the heating slow cooling end of the heating slow cooling zone 230 is located before the solidification end point. That is, the heating slow cooling zone 230 starts from a total cooling length extending from the lower nozzle of the continuous casting mold 300 in the drawing direction by more than 40%, and ends up not exceeding the end of the cooling length. By applying heat and slow cooling measures to the slab, the temperature gradient in the slab is reduced, the temperature difference between the surface of the slab and the inside is reduced, the growth of the columnar crystals is suppressed, and the occurrence of internal cracks in the slab is also avoided. Applicant's R&D team found through long-term research and development that if the heating slow cooling zone 230 starts at less than 40% of the total cooling length, it will easily lead to the conventional cooling zone being too short to perform a good transition and cause the slab surface. If the temperature rise is too large, the solidified section area is prone to internal cracks. For this reason, the applicant has creatively proposed that the heating slow cooling starting point is located at a total cooling length of more than 40%, and the heating slow cooling end point is before the solidification end point. In addition, it is worth noting that the heating slow cooling end of the heating slow cooling zone 230 is adapted to the performance of the final product. If the final product has a higher requirement on the core of the casting blank, the slow cooling zone 230 is heated while heating the slow cooling zone 230. The total length should also match the length of the pre-cooling zone 210 to ensure that the total amount of energy released during the continuous casting process is constant. For example, the longer the length of the super-cool zone 210, the longer the length of the heating zone 230, that is, the heating zone. The length of 230 is positively correlated with the length of the super-strong cold zone 210 and ensures a constant total energy release during the continuous casting process. The method of heating and cooling is to provide heating measures to the surface of the slab, and the heating energy value is greater than 5 kW/m ² kW/m ² .

Example 1

This embodiment is carried out on a 5 round round billet continuous casting machine of a steel mill. The cross section diameter of the billet is 380 mm. During the casting process, strong cold, weak cold and heating slow cooling measures are applied to the casting billet in the casting direction. The length of the zone 210, the cooling water flow density of the super-cooling zone 210, the heating slow cooling zone 230 heating the slow cooling starting point, and the heating slow cooling zone 230 heating provide heat as shown in Table 1; the super-strong cooling zone 210 is from the continuous casting mold 300 From the lower mouth to 22% L, the heating slow cooling zone 230 is at the 55% L position to the solidification end point. After the casting is finished, the slab is taken at a low magnification, and the columnar crystal looseness of the slab is analyzed, and the surface temperature at the time of complete solidification of the slab is measured. The specific parameters and results of the examples are shown in Table 1.

Example 2

The basic content of this embodiment is the same as that of the first embodiment. The difference between the cooling water flow density of the super-strong cooling zone 210, the heating slow cooling starting point position and the heating slow cooling zone 230 is different. The specific parameters are as shown in Table 1. After the casting is finished, the slab is taken at a low magnification, and the columnar crystal looseness of the slab is analyzed, and the surface temperature at the time when the slab is completely solidified is measured. The specific parameters and results of the examples are shown in Table 1.

Example 3

This embodiment is carried out on a 5 round round billet continuous casting machine of a steel mill. The cross section diameter of the billet is 700 mm. During the casting process, strong cold, weak cold and heating slow cooling measures are applied to the casting billet in the casting direction. The length of the zone 210, the cooling water flow density of the super-cooling zone 210, the heating slow cooling zone 230 heating the slow cooling starting point, and the heating slow cooling zone 230 heating provide heat as shown in Table 1; the super-strong cooling zone 210 is from the continuous casting mold 300 From the lower mouth to 17% L, the heating slow cooling zone 230 is at the 55% L position to the solidification end point. After the casting is finished, the slab is taken at a low magnification, and the columnar crystal looseness of the slab is analyzed, and the surface temperature at the time of complete solidification of the slab is measured. The specific parameters and results of the examples are shown in Table 1.

Example 4

The basic content of this embodiment is the same as that of the third embodiment. The difference between the cooling water flow density, the heating slow cooling starting point and the heating slow cooling zone 230 is different. The specific parameters are as shown in Table 1. After the casting is finished, the casting blank is taken at a low magnification, and the columnar crystal looseness of the casting blank is analyzed, and the surface temperature when the casting blank is completely solidified is measured. The specific parameters and results of the examples are shown in Table 1. A picture of the low magnification structure of the cast slab of Example 4 is shown in FIG.

Comparative example 1

The basic content of this embodiment is the same as that of Embodiment 4, except that the water flow density of the cooling strength of the surface of the slab is 200 L/m ² . After casting, take a low-magnification sample of the slab, perform low-fold analysis, analyze the columnar crystal looseness of the slab, and measure the surface temperature when the slab is completely solidified. The specific parameters and results of Comparative Example 1 are shown in Table 1. A picture of the low-magnification structure of the proportion 1 slab is shown in Fig. 4.

Table 1

Remarks: The length of the super cold zone 210 and the length of the heating slow zone 230 in the table are L, and L represents the total cooling length.

It can be seen from the implementation results that the columnar crystal structure in the solidification structure of the slab in Example 1-4 is relatively loose, the average columnar crystal looseness is less than 26.0 um, and the surface temperature of the slab is increased, which can effectively reduce the occurrence of internal cracks. Improve the quality of the slab to meet the demand for solidification structure of different products.

For further analysis, FIG. 3 is a schematic view showing the morphology of the microstructure of the slab of Example 4; FIG. 4 is a schematic view showing the microstructure of the slab of Comparative Example 1; wherein, FIG. 3 and FIG. 4 include a columnar crystal region 410, The equiaxed crystal region 420 and the loose pores 430, the slab columnar crystal region 410 in FIG. 4 has a relatively loose domain structure, and the columnar crystal region 410 has a loose pore 430, and the slab columnar crystal region 410 of FIG. 3 is densely organized and dendritic. Finely compact, the loose holes 430 of the columnar crystal regions 410 are substantially eliminated. Moreover, the average columnar grain looseness is reduced from 37.2 um to 26.0 um. The columnar crystal spacing and gap are reduced, the secondary surface layer and the core solidification structure of the slab are improved, the density of the near-layer columnar crystal of the slab is improved, and the internal crack is reduced. Further comparison can be found that, compared with Comparative Example 1, Example 4 not only reduces the columnar crystal spacing and gap, improves the secondary surface layer and core solidification structure of the cast strand, but also enlarges the proportion of equiaxed crystal regions 420, thereby improving The quality of the slab.

The invention has been described in detail above with reference to specific exemplary embodiments. It should be understood, however, that various modifications and changes can be made without departing from the scope of the invention as defined by the appended claims. The detailed description and drawings are to be regarded as illustrative and not restrictive In addition, the background art is intended to illustrate the state of the art and the meaning of the present invention, and is not intended to limit the invention or the application field of the present application and the present invention.

Claims

A method for controlling solidification structure of a slab during continuous casting, characterized in that a super-cooling zone (210) and a heating slow-cooling zone (230) are arranged in a section from the nozzle water nozzle to the end of the solidification end point, continuous casting The billet (100) is first subjected to super cooling in the super-cooling zone (210), and then heated and cooled in the heating slow cooling zone (230), wherein the cooling intensity of the heating slow cooling is less than the cooling intensity of the air cooling.
A method for controlling solidification structure of a slab during continuous casting according to claim 1, wherein a weak cooling zone is further disposed between the super-cooling zone (210) and the heating slow zone (230) ( 220), the weak cooling zone (220) has a cooling intensity that is less than a cooling intensity of the super-cooling.
A method for controlling solidification structure of a slab during continuous casting according to claim 2, wherein the super-cooling zone (210) has a water flow density of Q L/m 2 and the weak cooling zone (220) has a water flow density of q L/m 2 , Q ≥ 2q.
A method for controlling solidification structure of a slab during continuous casting according to claim 1, wherein the super-cooling starting point of the super-cooling zone (210) is located at the nozzle of the crystallizer, and the super-cool zone (210) The length of the ) is greater than 12% L, where L is the total cooling length.
A method for controlling solidification structure of a slab during continuous casting according to claim 1, wherein the distance between the heating slow cooling zone of the heating slow cooling zone (230) and the nozzle of the crystallizer crystallizer is greater than 40% L, where L is the total cooling length.
A method for controlling solidification structure of a slab during continuous casting according to claim 1, wherein the super-cooling zone (210) of the round billet continuous casting billet (100) has a water flow density of ≥ 465 L/m 2 , Or the super-cooling zone (210) of the rectangular billet continuous casting billet (100) has a water flow density of ≥ 490 L/m 2 , or the super-cooling zone (210) of the thick-plate continuous casting billet (100) has a water flow density of ≥ 255 L/m 2 .
A method for controlling solidification structure of a slab during continuous casting according to claim 1, characterized in that the surface of the slab is heated in a heating slow cooling zone (230), and the heating energy value is greater than 5 kW/m. 2 .
A method for controlling solidification structure of a slab during continuous casting according to any one of claims 1 to 6, characterized in that the heating slow cooling end of the heating slow cooling zone (230) is located before the solidification end point. .
A device for controlling solidification structure of a slab based on heating and slow cooling, characterized in that: a lower portion of the continuous casting mold (300) is provided with a super-strong cooling zone (210) and heating along the length direction of the continuous casting slab (100) The slow cooling zone (230), the super-cooling zone (210) is used to provide water spray cooling to the surface of the slab, and the heating slow cooling zone (230) is used to provide heat heating to the surface of the slab.
The apparatus for controlling the solidification structure of a slab based on heating slow cooling according to claim 8, wherein the surface of the continuous casting slab (100) of the heating slow cooling zone (230) is provided with an electromagnetic heating coil (231) or The heating cover (231), wherein the heating cover (231) is a steam heating cover or a combustible gas heating cover or a reflective heat insulation self-heating cover.
A device for controlling solidification structure of a slab based on heating slow cooling according to claims 8-9, characterized in that the front portion of the heating slow cooling zone (230) is provided with a weak cooling zone (220).