Cooling method and system for controlling corner cracking of micro-alloyed steel slabs

Abstract

To provide a cooling method and system for controlling corner cracking of a microalloyed steel slab.SOLUTION: By means of a narrow face foot roll type cooling device and strong cooling control in a wide face 1 zone or a wide face 2 zone of a cast piece, a tissue within a range of 0-10 mm under a skin of a corner of a microalloyed steel slab undergoes rapid phase transformation from austenite to ferrite within a narrow face foot roll zone, and its microalloyed carbonitrides are dispersed and precipitated. Then, by controlling an amount of water in a wide face 3 zone and a wide face 4 zone through slow cooling, and by completely re-austenitizing a tissue within a range of 0 to 10 mm under the skin of the corner of the slab to an exit of the wide face 4 zone, two phase transformations from austenite to ferrite and then from ferrite to austenite are performed on the tissue within the range of 0 to 10 mm under the skin of the corner of the slab to significantly refine crystal grains; and by highly plasticizing a corner tissue of the microalloyed steel slab, the occurrence of cracking there is prevented.SELECTED DRAWING: Figure 1

Description

Technical Field

[0001] The present invention belongs to the field of steelmaking - continuous casting, and specifically relates to a cooling method and system for controlling corner cracking of micro - alloy steel slabs.

Background Art

[0002] Adding alloying elements such as trace amounts of Nb, Al, B, V, etc. to steel can significantly refine the crystal grains of the structure of the finished steel product, improve mechanical properties such as the strength and toughness of the steel, and is widely used in the production of micro - alloy steel. However, in the actual continuous casting production process of the base metal of micro - alloy steel slabs containing elements such as Nb, Al, B, V, etc., transverse corner crack defects often occur at the corners, which limits the high - quality and high - efficiency production of micro - alloy steel.

[0003] There are many methods for controlling lateral cracking at the corners of microalloy steel slabs both in China and abroad. For example, patent application number 202110259907.X discloses a process for controlling corner cracking of thick slabs by optimizing the microalloy composition of the steel type, mold powder physical properties, mold and secondary cooling process, mold vibration and taper parameters, etc. Patent application number 201510976823.2 discloses a method for preventing warping defects at the edges of low-alloy high-strength steel during cold rolling by reducing the nitrogen content in the steel and adding a Ti alloy to reduce the precipitation of Nb(C,N) and AlN during the solidification process of the cast slab. Patent application number 201510928837.7 similarly discloses a method for preventing transverse cracking at the corners of continuously cast microalloyed steel slabs by adding a Ti alloy to steel to reduce the amount of Nb(C,N) precipitation during the slab solidification process and by overall controlling the amount of water in the secondary cooling. Invention patent number 201510158824.6 discloses a method for reducing transverse cracking at the corners of Nb-containing steel slabs based on a narrow-face dual-tapered chamfer mold, by controlling the nitrogen content in the steel, the mold water flow rate and temperature, the mold powder property parameters, and the amount of water in the secondary cooling zone. Such methods for controlling corner cracking of microalloyed steel slabs often improve the high-temperature plasticity of the corner structure of the slab and reduce crack occurrence by controlling the nitrogen content in the steel, adjusting the type and content of the alloy, optimizing the mold powder, and controlling the water distribution process for secondary cooling. However, in actual production, the type and content of the steel alloy are determined by its mechanical properties and cannot be significantly changed. The nitrogen content in steel is limited by smelting technology and is difficult to reduce significantly. Furthermore, optimizing the properties of the mold powder and simply improving or decreasing the water ratio in continuous casting does not alter the structure of the corner microstructure and grain dimensions of right-angled slabs, and therefore does not significantly improve the thermoplasticity of the corner microstructure of the slabs.

[0004] To effectively avoid the third brittle temperature zone of steel and reduce the occurrence of corner cracks in cast slabs, the invention patent No. 201610004640.9 discloses an apparatus and method for reducing corner cracks in microalloyed slabs by raising the temperature of the corners of the cast slab with a coil, thereby avoiding the high temperature of the corners of the cast slab from the third brittle temperature zone of steel. However, the secondary cooling zone of an actual continuous slab casting machine consists of a fan-shaped segment with densely arranged rows of rolls, leaving no place to install heating coils, and the inside of the strand is a high-temperature, high-humidity environment, making implementation difficult. In the actual continuous slab casting process, it is difficult to significantly increase the temperature of the corners that enter the straightening region of the right-angled slab by optimizing the secondary cooling water distribution process. In light of this challenge, patents such as patent numbers 201510846986.9 and 201120136707.7 utilize a chamfered mold, that is, by changing the four right-angled slabs produced with conventional right-angled molds to eight obtuse-angled structural slabs, the temperature of the corners that enter the straightening region of the slab is significantly increased, thereby effectively controlling the occurrence of corner cracks in microalloy steel slabs through a method for controlling corner cracks in continuously cast microalloy steel slabs that avoid the third brittle temperature zone of the steel.

[0005] According to research, the main reasons for frequent transverse cracking at corners in the continuous casting process of microalloy steel slabs containing elements such as Nb, Al, B, and V are as follows: Under the conditions of existing continuous slab casting processes, coarse austenite grains are very easily formed during the solidification process at the corners of the cast slab. During the subsequent cooling process, microalloy elements such as Nb, Al, B, and V in the steel combine with elements such as C and N to form carbides, nitrides, or carbonitrides, which precipitate in a chain-like manner at the grain boundaries of the steel structure, causing the grain boundaries to become brittle. Furthermore, if the temperature at the corners of the cast slab drops further to the ferrite transition temperature, the coarse austenite grain boundaries generate a network of proecutionary ferrite films, significantly weakening the plasticity and strength of the steel structure. When the cast slab enters the straightening zone, the straightening process causes the corners of the cast slab to crack along the grain boundaries due to insufficient plasticity, making them prone to forming transverse crack defects. Thus, refining the crystal grains in the corner structure of a continuous cast steel slab containing Nb, Al, B, V, etc., and dispersing and precipitating the microalloy carbonitrides to improve the overall plasticity of the steel structure is key to fundamentally controlling the occurrence of transverse cracks at the corners of a continuous cast microalloy steel slab.

[0006] Research has revealed that by implementing a circulating phase transformation control cooling process that rapidly transitions from austenite to ferrite and from ferrite to austenite in high-temperature steel structures, the grain size of the high-temperature steel structure can be significantly refined. This solves the problem of protereposition ferrite films forming on coarse austenite grains and subsequent grain boundaries, which drastically reduce the high-temperature plasticity of the steel. Furthermore, if the steel structure can be rapidly cooled within the precipitation temperature range of microalloy carbonitrides containing Nb, Al, B, V, etc., the microalloy carbonitrides can be dispersed and precipitated within the microstructure crystals. This solves the problem of grain boundary embrittlement caused by the chain-like concentration of carbonitrides at the grain boundaries during the solidification process of microalloy steels containing Nb, Al, B, V, etc., and fundamentally eliminates the occurrence of corner cracks in cast slabs.

[0007] Through theory and experimentation, it was found that the temperature at which "nose pits" precipitate at the carbonitride grain boundaries of currently dominant microalloy steels containing Nb and Al components is 900-970°C. By comparing the change in corner temperature along the strand direction during the continuous casting process of cast slabs, it was found that the strand position in this temperature range is mainly concentrated in the narrow foot roll region of the continuous casting machine. Therefore, it is necessary to perform strong spray cooling on the corners of the cast slabs within the narrow foot roll so that the structure quickly passes through the temperature at which carbonitrides containing N, b, and Al precipitate as "nose pits".

[0008] Furthermore, the corner temperature of the cast slab after it leaves the mold is often 950-1000°C. At this temperature, the steel structure is austenite, satisfying the requirement that the microstructure must be originally austenite before the rapid cyclic phase transformation process of austenite to ferrite and ferrite to austenite can be carried out. In addition, it is necessary to control the corner of the cast slab with strong spray cooling to promote the rapid transformation of the microstructure from austenite to ferrite. Moreover, because the solidified shell of the cast slab in the strand region from the mold exit to the vertical bend exit is thin, the corner of the cast slab, which has been strongly cooled through the narrow-face foot roll region, can rapidly recover its temperature to the complete austenitization temperature of the microstructure before leaving the secondary cooling zone 4. This enables the rapid cyclic phase transformation of the microstructure in the corner of the cast slab from austenite to ferrite and ferrite to austenite, and can refine the crystal grains.

[0009] However, in actual continuous casting production of slabs, conventional spray systems for narrow-face foot roll zones only have a structure with 3 to 6 single-row nozzles in the center. However, due to limitations in the nozzle spray angle and water volume distribution characteristics, the cooling water at the sprayed fan-shaped edges cannot efficiently cool the corners of the cast slab. As a result, rapid cooling of the high-temperature corners of the cast slab is difficult, and consequently, abrupt changes from austenite to ferrite and dispersed deposition of carbonitrides occur in the microstructure.

[0010] Currently, methods have been developed to refine the microstructure of continuously cast slabs by strongly cooling the corners, and to disperse and precipitate their microalloy carbonitrides. These methods mainly involve increasing the overall water volume on the wide or narrow surfaces of the slab. For example, patent no. 201010259985.1 discloses a method of increasing the overall water volume on the wide and narrow surfaces of a slab in the vertical section of a continuous casting machine by 2 to 5 times, and cooling the slab surface at a cooling rate of 3 to 10°C / s. However, practical applications by companies such as Baotie Group and Panzhihua Steel Group have revealed that significantly increasing the overall cooling water volume on the wide and narrow surfaces of a continuously cast slab tends to cause longitudinal crack defects on the wide surface, and that the effect of strong cooling on the localized corners of the slab is limited. Furthermore, cooling the wide and narrow surfaces of a reinforced slab in the vertical section promotes solidification of the slab, advances the solidification endpoint position, and modifies processes such as reduction of the solidification endpoint.

[0011] Patent No. 201210348907.8 discloses a secondary cooling control method for reducing lateral cracking at the corners of microalloy steel slabs, which involves increasing the overall cooling intensity of the slab after it leaves the mold, cooling the slab surface at a cooling rate of 3-8°C / s, dispersing and precipitating carbonitrides on the slab surface, causing a transformation from austenite to ferrite in the microstructure, and then refining the grain size of the steel microstructure by achieving a transformation from ferrite to austenite through a weak cooling temperature recovery. Similarly, Patent No. 201810964557.5 discloses a method for eliminating lateral cracking at the corners of cold-rolled slabs, which involves strongly cooling the slab overall within the wide-face foot roll zone to solidify surface precipitates in the matrix, and avoiding the formation of prodromal ferrite films at the grain boundaries of the surface microstructure by slowly cooling the slab in the bending section. The invention patents under application numbers 201210348907.8 and 201810964557.5 are conceptually similar to the patent under application number 201010259985.1, both of which strongly cool the corners of the cast slab by increasing the overall amount of cooling water in the secondary cooling high-temperature zone. In actual implementation, however, there are drawbacks such as the tendency for surface longitudinal cracks to occur on the wide surfaces of the cast slab, changes in the solidification end position of the cast slab, and poor localized strong cooling effect at the corners of the cast slab.

[0012] The invention patent, patent number 201510005720.1, discloses a slab corner strong spray cooling system that adapts to changes in slab width and independently controls the water volume, installed on both sides of the vertical bend below the narrow-face foot roll zone of a continuous casting machine, thereby strongly cooling and refining the crystal grains of the slab corner structure. The spray stand that strongly cools and sprays the slab corner is a horizontal drive device, and the nozzle can be adjusted to match the corner of slabs of different widths to strongly spray and cool them. However, in actual slab continuous casting, the space in the vertical bend is narrow, making it difficult to add an expansion / contraction control drive device inside and move the spray stand horizontally as a whole. Also, since the vertical bend is a high-temperature steam environment, it is difficult to use the drive structure for extended periods. Furthermore, the temperature of the slab corner below the narrow-face foot roll has already dropped to below 900°C, which is lower than the "nose" temperature for the precipitation of carbonitrides containing Nb, Al, B, etc., making it difficult to effectively control the dispersion and precipitation of these types of carbonitrides.

[0013] In response to the drawback of the spray stand being difficult to drive in patent no. 201510005720.1, the invention patent no. 201510534316.3 discloses a control system and method for refining the crystal grain structure of the corners of a cast slab by strongly cooling the corners of the cast slab by adding 3 to 7 sets of nozzles to the ends of the narrow-face foot roll zone of a continuous casting machine, which strongly spray and cool the corners of the inner and outer arcs of the cast slab. In this patent, the strong cooling spray stand is fixed and connected below the narrow-face foot roll. However, in actual production, the mold and its narrow-face foot roll extension spray stand must be lifted by a lifting cart and placed into the strand of the continuous casting machine. When being loaded, the lifting cart's vibrations make it prone to colliding with the extension strong cooling spray stand. Furthermore, a dedicated mold storage stand needs to be newly constructed to accommodate a mold equipped with the extension strong cooling spray stand. Furthermore, the spray structure of this patent is easy to install under a narrow-face foot roll, meaning that the temperature at the corners of the cast slab is also reduced to below 900°C, which is lower than the "nose point" temperature for the precipitation of carbonitrides containing Nb, Al, B, etc. Similarly, there is a problem in that the dispersion and precipitation of this type of carbonitride cannot be effectively controlled.

[0014] The invention patent no. 201810329636.9 discloses a control device and control method for cracking corners of microalloy steel thin slabs. This control device adds a strong spray system at the bottom of the narrow face of the mold, strongly cooling the corners of the thin slab at an average cooling rate of 20°C / sec to 35°C / sec, dispersing and precipitating microalloy carbonitrides at the corners of the thin slab, and refining the crystal grain structure of the corners of the thin slab. However, thin slab continuous casting machines differ significantly in structure from conventional slab, wide-thick slab, and extra-thick slab continuous casting machines. Thin slab continuous casting machines lack a foot roll structure below the narrow face of the mold. This patent only requires the addition of a set of staggered spray stands below the narrow face of the thin slab mold for strong cooling spray targeting the corners of the inner and outer arcs of the cast slab. On the other hand, beneath the narrow surface of a standard slab, wide-thick slab, or extra-thick slab continuous casting machine, a narrow-surface foot roll with a complex structure including side guide rollers and narrow-surface nozzles is positioned. Utility model patent No. 201820702023.0 similarly discloses an additional set of staggered strong cooling spray structures targeting the inner and outer arc corners of a thin slab, beneath the narrow surface of a thin slab mold, and this too is applicable only to thin slab continuous casting machines.

[0015] The invention patent no. 201911192737.7 discloses a method and apparatus for controlling the size of austenite crystal grains at the corners of a continuously cast slab. This apparatus shortens the narrow copper plate of the mold and installs multiple rows of high-cooling spray nozzles in the foot roll zone below it. The upper nozzles are inclined downward at an angle of 30 to 80 degrees relative to the slab surface, and the lower nozzles spray perpendicularly to the slab surface, thereby improving the cooling intensity of the narrow surface of the slab as it exits the mold and refining the austenite crystal grains at the corners of the continuously cast slab. However, this foot roll type high-cooling spray apparatus also strongly cools the entire narrow surface of the slab. Furthermore, its extended spray structure is similar to the invention patent no. 201510534316.3, making it unsuitable for installation on a mold production line.

[0016] Furthermore, in academic papers titled "Research and Development and Application of Corner Crack Control Technology for Continuously Cast Microalloy Steel Slabs" and "A Novel Secondary Cooling Process for Corner Crack Control of Continuously Cast Niobium-Containing Microalloy Steel Slabs," a strong cooling structure for slab corners based on a narrow-face foot roll of the mold was developed. This strongly cools the corners of the slab locally and is controlled by an independent circuit. As can be seen from the figure, this cooling control structure is still a pair of spray stands mounted below the narrow-face foot roll that spray the inner arc corner or the inner and outer arc corners of the slab, and its essence is the practical application of the patented technology of patent number 201510534316.3.

[0017] Therefore, in conjunction with the actual structure of continuous casting machines for standard slabs, wide slabs, and extra-thick slabs, the characteristics of continuous casting production technology for microalloy steel, and actual production requirements such as online width adjustment of the continuous casting machine, we have developed a cooling control device and its automatic water distribution control system that can be easily installed on-site below the exit of the continuous casting mold and stably perform strong splatting and cooling of the slab corner structure. This invention has developed a crack control cooling process that satisfies the refinement of crystal grains and dispersion precipitation of microalloy carbonitrides through circulating phase transformation from austenite to ferrite and from ferrite to austenite in the range of 0 to 10 mm below the surface of the slab corner, thereby highly plasticizing the slab corner structure. As a result, it is possible to continuously cast and produce the corners of conventional microalloy steel slabs, wide slabs, and extra-thick slabs without defects, which is of great significance and has promising future potential for widespread adoption and application. [Overview of the project] [Problems that the invention aims to solve]

[0018] The technical problem that this invention aims to solve is to provide a cooling method and system for controlling corner cracking of microalloy steel slabs, in order to address the shortcomings of the conventional corner cracking control technology for microalloy steel slabs described above. [Means for solving the problem]

[0019] One aspect of the present invention is a cooling method for controlling corner cracking of a microalloy steel slab, To disperse and precipitate microalloy carbonitrides by causing the microstructure in the subcutaneous 0-10 mm range of the corners of a microalloy steel slab to transition from austenite to ferrite within the zone of the narrow-face foot roll, the average cooling rate and minimum cooling temperature of the microstructure in the subcutaneous 0-10 mm range of the corners of a microalloy steel slab to be continuously cast are determined in the strong cooling zone of the narrow-face foot roll. In order to completely re-austenitize the microstructure in the subcutaneous 0-10 mm range of the corners of a microalloy steel slab up to the exit of the wide surface 4 zone, the steps are to determine the average temperature recovery rate in the wide surface 3 zone and wide surface 4 zone and the temperature recovery temperature at the end of the wide surface 4 zone for the microstructure in the subcutaneous 0-10 mm range of the corners of a microalloy steel slab to be continuously cast, The steps include determining the amount of cooling water for the narrow-sided foot-roll type cooling device located beneath the mold and for the wide-sided zones 1 to 4, based on the average cooling rate, the minimum cooling temperature, the average temperature recovery rate in the wide-sided zone 3 and zone 4, and the temperature recovery temperature at the end of the wide-sided zone 4, The present invention provides a cooling method for controlling corner cracking of a microalloy steel slab, comprising the steps of cooling the microalloy steel slab located within secondary cooling zones 1 to 4 using the determined narrow-face foot-roll type cooling device and the amount of cooling water in the wide-face zones 1 to 4.

[0020] Furthermore, the steps include obtaining parameters for the continuous casting process of the microalloy steel slabs to be produced by continuous casting, Based on the parameters of the continuous casting process, a three-dimensional transient temperature field calculation model of the continuously cast slab, including the crystallizer and secondary cooling zones 1-4, is created using commercial finite element software or self-programming, and the temperature field distribution of the microalloy steel slab to be produced by continuous casting is calculated. The method further includes the step of determining, from the temperature field distribution of the microalloy steel slab calculated above, the average cooling rate and minimum cooling temperature in the narrow-face foot roll zone of the microstructure in the 0-10 mm subsurface range at the corner of the microalloy steel slab to be continuously cast, and the average temperature recovery rate and temperature recovery temperature at the end of the wide-face zone 4 of the microstructure in the 0-10 mm subsurface range at the corner of the microalloy steel slab to be continuously cast, The parameters of the continuous casting process are characterized by including the slab cross-sectional dimensions, casting speed, degree of molten steel superheating of the microalloy steel slab to be continuously cast, the amount of cooling water and temperature difference on the wide side of the crystallizer, and the amount of cooling water and temperature difference on the narrow side of the crystallizer.

[0021] Furthermore, the slab cross-sectional dimensions are 2100 mm × 250 mm, the casting speed is 0.8 to 1.3 m / min, the molten steel superheat of the microalloy steel sheet to be continuously cast is 25°C, the cooling water volume for the wide side of the crystallizer is 3250 L / min with a water temperature difference of 7.5°C, and the cooling water volume for the narrow side of the crystallizer is 390 L / min with a water temperature difference of 8.2°C.

[0022] Furthermore, the microstructure within a 0-10 mm subsurface area at the corners of the microalloy steel slabs targeted for continuous casting production is characterized in that, in the narrow-face foot roll strong cooling zone, the average cooling rate is 5°C / s or more and the minimum cooling temperature is 550-600°C; in the wide-face zone 3 and wide-face zone 4, the average temperature recovery rate is 3.5°C / s or more; and at the end of wide-face zone 4, the temperature recovery temperature is 900°C or more.

[0023] Another aspect of the present invention is also To disperse and precipitate microalloy carbonitrides by causing the microstructure in the subcutaneous 0-10 mm range of the corners of microalloy steel slabs to transition from austenite to ferrite within the narrow-face foot roll zone, a first parameter determination module is used to determine the average cooling rate and minimum cooling temperature in the narrow-face foot roll strong cooling zone of the microstructure in the subcutaneous 0-10 mm range of the corners of microalloy steel slabs targeted for continuous casting production, and In order to completely re-austenitize the structure within the range of 0 to 10 mm below the surface at the corners of the micro-alloy steel slab, a second parameter determination module for determining the average temperature recovery rate in the wide surface 3-zone and wide surface 4-zone, and the temperature recovery temperature at the end of the wide surface 4-zone of the structure within the range of 0 to 10 mm below the surface at the corners of the micro-alloy steel slab to be continuously cast, A third parameter determination module for determining the narrow surface foot roll type cooling device and the cooling water amounts in the wide surface 1-4 zones based on the average cooling rate, the minimum cooling temperature, the average temperature recovery rate in the wide surface 3-zone and wide surface 4-zone, and the temperature recovery temperature at the end of the wide surface 4-zone, A cooling module for cooling the micro-alloy steel slab located in the secondary cooling 1-4 zones with the determined narrow surface foot roll type cooling device and the cooling water amounts in the wide surface 1-4 zones, and a cooling system for controlling corner cracking of the micro-alloy steel slab is provided.

[0024] Furthermore, the narrow surface foot roll type cooling device A first noise group provided at the frame edge on the surface side of the narrow surface foot roll and communicating with the water channel, A second noise group provided at the edge on the other side of the frame on the surface side of the narrow surface foot roll, and having a width symmetric to the frame on the surface side of the narrow surface foot roll of the first noise group, The water channel provided within the frame of the narrow surface foot roll and communicating with the first noise group and the second noise group respectively, The water supply pipe communicating with the water channel, provided with a flow meter, a pneumatic adjustment valve and a shut-off valve, the flow meter, the pneumatic adjustment valve and the shut-off valve being electrically connected to the cooling module respectively, turning on the shut-off valve according to the water amount of the narrow surface foot roll type cooling device determined by the cooling module, and controlling the opening degree of the pneumatic adjustment valve according to the flow rate of the water supply pipe detected by the flow meter.

[0025] Furthermore, the narrow-face foot-roll type cooling device further includes an industrial computer, a human-machine interaction interface, and a PLC control system, wherein the industrial computer, flow meter, and pneumatic regulating valve are connected to the PLC control system via cables, the industrial computer is communicably connected to the PLC control system, the human-machine interaction interface is mounted on the industrial computer, and includes a system maintenance backend and a real-time operating status information display / operation frontend interface, wherein the system maintenance backend includes a data communication module, a real-time data acquisition module, a water meter setting module, a flow calibration module, a real-time water volume distribution module, a data storage module, and a history data query module. The data communication module connects the industrial computer and the PLC control system in real time for communication, and displays the current communication status between the industrial computer and the PLC control system. The real-time data acquisition module collects data in real time on the steel type, furnace number, casting speed, pneumatic control valve opening, and flow meter flow rate of the microalloy steel slabs targeted for continuous casting production. The water meter setting module has the function of creating, modifying, and saving water meter settings. The real-time water volume distribution module distributes the amount of cooling water to match the current casting speed, according to the water volume meter and water volume distribution mode selected by the real-time operating status information display / operation front-end interface. The data storage module stores real-time data in a predetermined database, including steel type, furnace number, casting speed, pneumatic control valve opening, flow meter flow rate, and the current time of the system, corresponding to the data acquisition cycle. The aforementioned historical data query module retrieves data from the data storage database and extracts the data to be queried based on the data query method and data query range selected by the real-time operating status information display / operation front-end interface.

[0026] Furthermore, the first and second noise groups are provided on both sides of the existing intermediate row noise group of the narrow-face foot roll, with 4 to 6 noises evenly distributed along the direction of the casting speed of the microalloy steel slab to be continuously cast, the centers of the 4 to 6 noises of the first noise group are on the same straight line, the straight line in which the centers of these 4 to 6 noises of the first noise group are located is parallel to the straight line in which the centers of the noises of the existing intermediate row noise group are located, the second noise group is located on the other side of the existing intermediate row noise group, and the centers of its 4 to 6 noises are on the same straight line, and these 4 to 6 noises of the second noise group The line in which the center of the noise group is located is parallel to the line in which the center of the noise group of the existing intermediate row is located, the 4 to 6 noises of the first noise group and the 4 to 6 noises of the second noise group are at the same height in pairs, the highest position of the noises of the first noise group and the second noise group starts from the topmost or second-highest noise of the existing intermediate row, the mounting height of each noise is the same as the height of the noise of the existing intermediate row at the corresponding height, and the distance between two adjacent noises in the first noise group is the same as the distance between two adjacent noises in the second noise group. The noise injection angle of the first noise group is 45° to 90°, the vertical height from the end of the noise to the surface of the narrow face of the cast slab is 40 to 100 mm, and the axial extension of each noise in the noise group intersects with the corner of the corresponding narrow face of the cast slab. The noise injection angle of the second noise group is -45° to -90°, the vertical height from the end of the noise to the surface of the narrow face of the cast slab is 40 to 100 mm, and the axial extension of each noise in the noise group intersects with the corner of the corresponding narrow face of the cast slab. The effective width of the cooling water injected from the noise of the first noise group and the noise of the second noise group on the corner of the narrow face of the microalloy steel slab that is the target of continuous casting production is 30 to 60 mm from the corner toward the center of the narrow face.

[0027] Further embodiments of the present invention also include An industrial computer device comprising memory, a processor, and a computer program stored in the memory and operable on the processor, The present invention provides an industrial computer device characterized in that, upon execution of the computer program, the processor implements a step of a cooling method for controlling corner cracking of any of the above-mentioned microalloy steel slabs.

[0028] Another aspect of the present invention is also An industrial computer-readable storage medium that stores computer programs, The computer program, when executed by a processor, provides an industrial computer-readable storage medium characterized by realizing a step in a cooling method for suppressing corner cracking of a microalloy steel slab as described above. [Effects of the Invention]

[0029] The cooling method and system for controlling corner cracking of microalloy steel slabs according to the present invention, compared to the prior art, rapidly causes a phase transformation from austenite to ferrite in the microstructure within a 0-10 mm subsurface range of the corner of the microalloy steel slab within the zone of the narrow-face foot roll, dispersing and precipitating the microalloy carbonitrides. Then, by controlling the amount of water in the wide-face zones 3 and 4 through slow cooling, the microstructure within a 0-10 mm subsurface range of the corner of the slab is completely re-austenitized by the exit of the wide-face zone 4. This causes two phase transformations in the microstructure within a 0-10 mm subsurface range of the corner of the slab, from austenite to ferrite, and then from ferrite to austenite, significantly refining the crystal grains and increasing the plasticity of the corner microstructure of the Nb and Al-containing microalloy steel slab, thereby suppressing the occurrence of cracks there. [Brief explanation of the drawing]

[0030] The following drawings of the present invention are used hereto illustrate the present invention as part of embodiments of the present invention. The drawings show embodiments of the present invention and their descriptions, which are intended to interpret the principles of the present invention. [Figure 1] This is a schematic flowchart of a cooling method for controlling corner cracking of a microalloy steel slab according to an embodiment of the present invention. [Figure 2] This is a schematic flowchart of a cooling method for controlling corner cracking of a microalloy steel slab according to another embodiment of the present invention. [Figure 3] This is a transmission electron microscope image of the structural precipitates at the corners of a cast slab of Nb-containing microalloy steel according to the present invention. [Figure 4] This is the metallographic appearance of the corner structure of a cast slab according to the present invention. [Figure 5] This is a schematic diagram showing the connections of a module for a cooling system for controlling corner cracking of a microalloy steel slab according to one preferred embodiment of the present invention. [Figure 6] This is a schematic diagram of the structure of a slab-narrow-face foot-roll type cooling device according to an embodiment of the present invention. [Figure 7] This is a schematic diagram of the structure of a water supply piping according to an embodiment of the present invention. [Figure 8] This is a schematic diagram of a partial structure of a slab-narrow-face foot-roll type cooling device according to an embodiment of the present invention. [Figure 9] This figure shows a slab-narrow surface foot roll type cooling device and intermediate noise lateral arrangement for strongly cooling the corners of the narrow surfaces of the inner and outer arches of a cast slab according to an embodiment of the present invention. [Figure 10] This is a block diagram illustrating the operating principle and logic of a slab-narrow-face foot-roll type cooling device according to an embodiment of the present invention. [Figure 11] This is a schematic diagram of the structure of an industrial computer device in one embodiment of the present invention. [Figure 12] This is a schematic diagram of another structure of an industrial computer device in one embodiment of the present invention. [Modes for carrying out the invention]

[0031] The following description provides many specific details to give a more complete understanding of the invention. However, as will be apparent to those skilled in the art, the invention can be implemented without requiring one or more of these details. In other examples, some technical features known to those skilled in the art are not described in order to avoid confusion with the invention.

[0032] Furthermore, the terms used herein are used solely to describe specific embodiments and are not intended to limit the exemplary embodiments of the present invention. As used herein, the singular form is also intended to include the plural form unless specifically indicated in the context. In addition, when the terms “contains” and / or “compose” are used herein, they indicate the presence of such features, wholes, steps, actions, elements, and / or components, but do not exclude the presence or addition of one or more other features, wholes, steps, actions, elements, components, and / or combinations thereof.

[0033] Hereinafter, exemplary embodiments of the present invention will be described in more detail with reference to the drawings. However, these exemplary embodiments can be carried out in various different forms and should not be construed as being limited to the embodiments described herein. It should be understood that these embodiments are provided to make the disclosure of the present invention complete and thorough and to fully convey the concept of these exemplary embodiments to those skilled in the art.

[0034] The cooling method for controlling corner cracking of a microalloy steel slab according to the present invention includes steps S101 to S104, as shown in Figure 1.

[0035] S101 determines the average cooling rate and minimum cooling temperature in the narrow-face foot roll strong cooling zone of the microstructure within the subcutaneous 0-10 mm range at the corners of microalloy steel slabs targeted for continuous casting production.

[0036] S102 determines the average temperature recovery rate in the broad surface 3 zone and broad surface 4 zone of the microalloy steel slabs subject to continuous casting production, within a subcutaneous range of 0-10 mm at the corners, and the temperature recovery temperature at the end of the broad surface 4 zone.

[0037] S103, Based on the average cooling rate, the minimum cooling temperature, the average temperature recovery rate in wide surface zone 3 and wide surface zone 4, and the temperature recovery temperature at the end of wide surface zone 4, the amount of cooling water for the slab narrow surface foot roll type cooling device and wide surface zones 1 to 4 is determined.

[0038] S104, the microalloy steel slab located within the secondary cooling zones 1 to 4 is cooled using the determined slab width narrow surface foot roll type cooling device and the cooling water volume for the wide surface zones 1 to 4.

[0039] The following describes an example of a cooling method for controlling corner cracking in an AH36 Nb-containing microalloy steel slab with a thickness of 250 mm and a width of 2100 mm. The steel composition is shown in Table 1.

[0040] Table 1. Main components (wt%) of AH36 Nb-containing high-strength ship plate steel. JPEG2023153039000002.jpg17170

[0041] In this embodiment, a cooling method for controlling corner cracking of microalloy steel slabs is provided by using a narrow-face foot roll to strongly cool the corners of the narrow faces of the inner and outer arches of a 250 mm thick slab targeted for continuous casting production. In response to changes in the casting speed at the continuous casting site, the microstructure in the 0-10 mm subsurface range of the slab corners undergoes a rapid cyclic phase transformation from austenite to ferrite, and then from ferrite to austenite, thereby refining the crystal grains and dispersing and precipitating Nb(C,N). This is achieved by distributing the amount of cooling water corresponding to each of the 1-4 wide zones online in real time. In continuous casting of AH36 Nb-containing steel slabs, the room-temperature ferrite crystal grains in the 0-10 mm subsurface range of the four corners of the slab are refined to 35 μm or less, dispersing and precipitating Nb(C,N) and increasing plasticity, thereby controlling the occurrence of corner cracking of the slab.

[0042] Based on the slab narrow-face foot-roll type cooling device and the amount of cooling water corresponding to each of the wide-face 1-4 zones determined in this invention, the microalloy steel slabs to be continuously cast are strongly cooled and controlled to rapidly transition the microstructure in the 0-10 mm subsurface range of the corners of the microalloy steel slab from austenite to ferrite within the narrow-face foot-roll zone, dispersing and precipitating the microalloy carbonitrides. Next, the amount of water in the wide-face 3 zone and wide-face 4 zone is controlled by slow cooling to completely re-austenitize the microstructure in the 0-10 mm subsurface range of the corners of the cast slab by the exit of the wide-face 4 zone. This causes a cyclic phase transformation of the slab corner microstructure from austenite to ferrite, and then from ferrite to austenite, significantly refining the crystal grains and increasing the plasticity of the corner microstructure of the AH36 Nb-containing microalloy steel slab, thereby controlling the occurrence of cracks there.

[0043] In some embodiments, as shown in Figure 2, the cooling method further includes steps S201 to S203.

[0044] S201, parameters of the continuous casting process for the microalloy steel slabs to be produced by continuous casting are obtained.

[0045] Here, the parameters of the continuous casting process include the slab cross-sectional dimensions, casting speed, degree of superheating of the molten steel slab to be continuously cast, the amount of cooling water and temperature difference on the wide side of the crystallizer, and the amount of cooling water and temperature difference on the narrow side of the crystallizer.

[0046] The cross-sectional dimensions of the cast slab are 2100 mm x 250 mm, the casting speed is 0.8 to 1.3 m / min, the superheating of the molten steel used to cast the microalloy steel sheets to be produced by continuous casting is 25°C, and the crystallizer is The cooling water flow rate for the wide surface is 3250 L / min and the water temperature difference is 7.5°C, while the cooling water flow rate for the narrow surface of the crystallizer is 390 L / min and the water temperature difference is 8.2°C.

[0047] S202, based on the parameters of the continuous casting process, a three-dimensional transient temperature field calculation model of the continuously cast slab, including the crystallizer and secondary cooling zones 1-4, is created using commercial finite element software or self-programming, and the temperature field distribution of the microalloy steel slab to be produced by continuous casting is calculated.

[0048] S203. From the temperature field distribution of the microalloy steel slab calculated above, the average cooling rate and minimum cooling temperature in the narrow surface foot roll zone of the microstructure in the 0-10 mm subsurface range at the corner of the microalloy steel slab to be continuously cast are determined, as well as the average temperature recovery rate in the wide surface 3 zone and wide surface 4 zone of the microstructure in the 0-10 mm subsurface range at the corner of the microalloy steel slab to be continuously cast, and the temperature recovery temperature at the end of the wide surface 4 zone are determined.

[0049] Furthermore, the microstructure within a 0-10 mm subcutaneous area at the corners of the microalloy steel slabs subject to continuous casting production has the following characteristics: in the narrow-face foot roll strong cooling zone, the average cooling rate is 5°C / s or higher, and the minimum cooling temperature is 550-600°C; in the wide-face zone 3 and wide-face zone 4, the average temperature recovery rate is 3.5°C / s or higher, and the temperature recovery temperature at the end of wide-face zone 4 is 900°C or higher.

[0050] Here, for AH36 steel continuously cast slabs based on Table 2, the average cooling rate in the narrow-face foot roll zone, the average temperature recovery rate in the wide-face 3 zone and wide-face 4 zone, and the temperature recovery temperature at the end of the wide-face 4 zone were determined at various casting rates for the microstructure in the 0-10 mm subsurface range at the corners of the microalloy steel slabs to be continuously cast. Then, the existing intermediate row noise group 10, first noise group 11, second noise group 12 of the slab narrow-face foot roll shown in Table 2, and the cooling water volume for the wide-face 1-4 zones were distributed to produce prototypes of continuously cast slabs with a cross-section of 2100 mm × 250 mm. The microstructure in the 0-10 mm subsurface range at the corners of the inner and outer arches of the microalloy steel slabs obtained from the prototypes was detected using a transmission microscope and a metallurgical microscope, and the dispersed distribution of Nb(C,N) and the grain refinement structure at 10 mm subsurface at the corners of the slabs shown in Figures 3 and 4 were obtained. The slab narrow-face foot-roll type cooling device corresponding to the "cooling method" at each casting speed shown in Table 2, and the cooling water volume corresponding to each of the wide-face zones 1 to 4, are used in the cooling method to control corner cracking in the continuous casting of AH36 Nb-containing steel slabs with a cross-section of 2100 mm × 250 mm.

[0051] Table 2. Relationship between casting speed and water volume in the continuous casting section of AH36 steel with a cross-section of 2100 mm x 250 mm (water volume unit: l / min) JPEG2023153039000003.jpg83170 Note: In Table 2, A represents a specific water volume value.

[0052] The cooling method for controlling corner cracking of microalloy steel slabs according to the present invention can effectively and strongly cool the corners of continuously cast microalloy steel slabs located within the narrow-face foot roll zone of a continuous slab casting machine, and satisfies the requirements of grain refinement by circulating phase transformation of the slab's corner structure and strong cooling by the dispersion precipitation process of microalloy carbonitrides.

[0053] The cooling system for controlling corner cracking of microalloy steel slabs according to the present invention includes a first parameter determination module, a second parameter determination module, a third parameter determination module, and a cooling module, as shown in Figure 5. Each functional module will be described in detail below.

[0054] The first parameter determination module 51 determines the average cooling rate and minimum cooling temperature in the narrow-face foot roll strong cooling zone of the microstructure within a 0-10 mm subcutaneous range at the corners of the microalloy steel slabs to be continuously cast.

[0055] The second parameter determination module 52 determines the average temperature recovery rate in the wide surface zone 3 and wide surface zone 4, and the temperature recovery temperature at the end of wide surface zone 4, for the microstructure in the subcutaneous range of 0-10 mm at the corners of the microalloy steel slabs to be continuously cast.

[0056] The third parameter determination module 53 determines the slab narrow surface foot roll type cooling device and the amount of cooling water for wide surface zones 1 to 4 based on the average cooling rate, the minimum cooling temperature, the average temperature recovery rate in wide surface zone 3 and wide surface zone 4, and the temperature recovery temperature at the end of wide surface zone 4.

[0057] The cooling module 54 cools the microalloy steel slabs located within the secondary cooling zones 1 to 4 using the determined slab width, foot-roll type cooling device for the narrow side and the cooling water volume for the wide side zones 1 to 4.

[0058] In the cooling system for controlling corner cracking of microalloy steel slabs according to the present invention, compared to conventional technology, the narrow-face foot-roll type cooling device and strong cooling control in the wide-face zone 1 and zone 2 of the cast slab rapidly cause a phase transformation from austenite to ferrite in the narrow-face foot-roll zone of the microalloy steel slab's corners within a range of 0 to 10 mm below the surface, dispersing and precipitating the microalloy carbonitrides. Next, by controlling the amount of water in the wide-face zone 3 and zone 4 through slow cooling, the microalloy structure within a range of 0 to 10 mm below the surface of the cast slab's corners is completely re-austenitized by the exit of the wide-face zone 4. This causes a cyclic phase transformation from austenite to ferrite, and then from ferrite to austenite, in the slab's corner structure, significantly refining the crystal grains and increasing the plasticity of the corner structure of the microalloy steel slab, thereby suppressing the occurrence of cracks there.

[0059] In one embodiment, the cooling system is A parameter acquisition module for acquiring parameters of the continuous casting process of microalloy steel slabs that are subject to continuous casting production, Based on the parameters of the continuous casting process, a three-dimensional transient temperature field calculation model of the continuous casting slab, including the crystallizer and secondary cooling zones 1-4, is created using commercial finite element software or self-programming, and a temperature field distribution range acquisition module is provided to calculate the temperature field distribution of the microalloy steel slab to be produced by continuous casting. The system further includes a parameter determination module that determines, from the calculated temperature field distribution of the microalloy steel slab, the average cooling rate and minimum cooling temperature in the narrow-face foot roll zone of the microstructure within 0-10 mm below the surface at the corner of the microalloy steel slab to be continuously cast, as well as the average temperature recovery rate in the wide-face 3 zone and wide-face 4 zone of the microstructure within 0-10 mm below the surface at the corner of the microalloy steel slab to be continuously cast, and the temperature recovery temperature at the end of the wide-face 4 zone.

[0060] In one embodiment, as shown in Figures 6-9, the slab narrow-face foot roll type cooling device includes a first noise group, a second noise group, a water channel 1, and a water supply pipe 2. The first noise group is provided on the edge of the frame 3 on the narrow-face foot roll surface side and communicates with the water channel 1. The second noise group is provided on the other edge of the frame 3 on the narrow-face foot roll surface side and is symmetrical in width to the frame 3 on the narrow-face foot roll surface side of the first noise group. The water channel 1 is provided within the narrow-face foot roll frame 3 and communicates with the first and second noise groups, respectively. The water supply pipe 2 communicates with the water channel 1. A flow meter 4, a pneumatic regulating valve 5, and a shut-off valve 6 are provided. The flow meter 4, pneumatic regulating valve 5, and shut-off valve 6 are electrically connected to the cooling module. The cooling module turns on the shut-off valve 6 according to the determined water volume of the slab narrow-face foot roll type cooling device and controls the opening of the pneumatic regulating valve 5 according to the flow rate of the water supply pipe detected by the flow meter 4.

[0061] The slab narrow-face foot roll type cooling device according to the present invention is based on the narrow-face foot roll of a continuous casting machine, with an external water supply pipe 2 added to the narrow-face foot roll, a water channel 1 provided within the frame 3 on the surface side of the narrow-face foot roll, and a first noise group and a second noise group provided at the foot roll edge that strongly cools the corners of the narrow faces of the inner and outer arches of the microalloy steel slab. Here, the water supply pipe 2 is independent of the noise group members on the side of the narrow-face foot roll, and is connected to the main secondary cooling water supply pipe 2 in the secondary cooling hydro valve station via a stainless steel pipe of dimensions DN50 or DN65, and then sequentially connected to the water channel control and detection elements of the shut-off valve 6, pneumatic regulating valve 5, and flow meter 4. When laid near the vibration frame 3 of the crystallizer, it is divided into two and connected via metal hoses to water inlets 7 added to the frame 3 on the surface side of the narrow-face foot roll on both sides of the crystallizer. The principles for designing the water supply capacity of the external water supply piping 2 added to the frame 3 on the surface side of the narrow-face foot roll are as follows: The water supply capacity should be increased by 20% from the standard amount sufficient to achieve the dispersion deposition of microalloy carbonitrides and efficient transition from austenite to ferrite in the range of 0-10 mm below the surface at the four corners of the slab at the maximum casting speed of continuous casting. The flow rate parameters of each control and sensing element of the external water supply piping 2 added to the frame 3 on the surface side of the narrow-face foot roll should be adjusted to match the water supply capacity of the water supply piping 2. The nominal diameter of the metal hose 7 connected to the water receiving section added to the frame 3 on the surface side of the narrow-face foot roll on both sides of the crystallizer should be DN40 or DN50, where the frame 3 on the surface side of the narrow-face foot roll is located below the crystallizer.

[0062] In one embodiment, as shown in Figure 6, the slab-narrow-face foot-roll type cooling system further includes an industrial computer 8, a human-machine interaction interface, and a PLC control system 9. The industrial computer 8, the PLC control system 9, a flow meter 4, and a pneumatic regulating valve 5 are connected to the PLC control system 9 via cables. The industrial computer 8 is communicatively connected to the PLC control system 9. The human-machine interaction interface is installed inside the industrial computer 8 and includes a system maintenance backend and a real-time operating status information display / operation frontend interface. The system maintenance backend includes a data communication module, a real-time data acquisition module, a water meter setting module, a flow calibration module, a real-time water volume distribution module, a data storage module, and a history data query module. The data communication module connects the industrial computer 8 and the PLC control system 9 in real-time and displays the current communication status between the industrial computer 8 and the PLC control system 9. The real-time data acquisition module collects data in real time on the steel type, furnace number, casting speed, pneumatic regulating valve opening, and flow rate of four flow meters for microalloy steel targeted for continuous casting production. The water meter setting module has the function of creating, modifying, and saving water meters. The real-time water distribution module distributes the amount of cooling water to match the current casting speed according to the water meter and water distribution mode in the real-time operating status information display / operation front-end interface. The data storage module stores real-time data corresponding to the data acquisition cycle, such as steel type, furnace number, casting speed, pneumatic regulating valve opening, flow rate of four flow meters, and the system's current time, in a predetermined database. The history data query module retrieves the data storage database and extracts the data to be queried based on the data query method and data query range selected by the real-time operating status information / display operation front-end interface.

[0063] Here, the data acquisition cycle of the real-time data acquisition module is generally set to 0.5 to 3 seconds. The flow rate calibration module calibrates the relationship between the pneumatic regulating valve opening and the flow rate, and the required amount of water can be accurately delivered regardless of whether the real-time operating status information display / operation front-end interface selects either the pneumatic regulating valve opening water rate delivery mode or the flow rate water rate delivery mode. The real-time operating status information display / operation front-end interface includes two parts: a real-time operating status display area and an operation area. The actual operating status display area displays information such as the continuous casting steel type, furnace number, casting speed, pneumatic regulating valve opening, actual delivered water rate, and set delivered water rate in real time in the form of numbers and curves. The operation area consists of a water rate delivery mode selection dropdown list, a safety water rate setting key, a water meter selection dropdown list, a history data query key, a back-end maintenance key, and a system termination key. Of these, the water rate delivery mode selection dropdown list includes pneumatic regulating valve opening water rate delivery mode, flow rate water rate delivery mode, and safety water rate mode. Regardless of whether the pneumatic regulating valve opening water volume distribution mode or the flow rate water volume distribution mode is selected, the system uses the water volume real-time distribution module to accurately distribute the water volume to match the current casting speed, based on the water volume meter selected by the real-time operating status information display / operation front-end interface, according to the relationship between the pneumatic regulating valve opening and water volume calibrated by the flow rate calibration module. The safety water volume mode is a constant water volume value distributed by the water volume real-time distribution module regardless of the casting speed, and may generally be set to 40-80 L / min. This value is set and changed by the safety water volume setting key. The water volume meter selection dropdown list has the function of automatically associating with water volume meters created by the maintenance backend. When a water volume meter is selected through the water volume meter selection dropdown list, the water volume real-time distribution module matches the water volume meter with the corresponding name, selects the mode selected through the list in the water volume distribution mode according to the current casting speed, and accurately distributes the water volume.The historical data query key provides some or all of the information, such as the queried furnace number, casting speed, pneumatic control valve opening, and actual water delivery volume, in the form of a curve or data table, allowing the operator to query according to time period, single furnace number, or multiple furnace numbers. The backend maintenance key functions as a channel to access the system maintenance backend. The system termination key terminates and shuts down the system.

[0064] The PLC control system 9 is connected to the industrial computer 8, the control valve, and the flow meter 4. The PLC control system 9 converts the signals from the control valve and the flow meter 4 and transmits them to the industrial computer 8. These signals are received and stored by the Human-Machine Interaction Interface system maintenance backend and displayed by the Real-Time Operating Status Information Display / Operation Frontend Interface. Based on the water volume (calibrated by the flow calibration module and converted to the pneumatic control valve opening) or pneumatic control valve opening signal delivered by the Human-Machine Interaction Interface, the PLC control system 9 adjusts the opening of the control valve in real time, thereby controlling and accurately delivering the water volume of the cooling system to control cracking at the corners of the slab in real time.

[0065] As shown in Figures 7 to 10, the operating principle and logic of the slab-narrow-face foot-roll type cooling system are as follows.

[0066] When the control system starts up, the backend maintenance interface determines whether communication between the industrial computer 8 and the PLC control system 9 is successful via the communication module with the PLC control system 9. If communication fails, it notifies of the communication failure; otherwise, it reads the relationship between the pneumatic regulating valve opening and flow rate, and the safe flow rate, which were saved before the system was last shut down. If recalibration of the relationship between the pneumatic regulating valve opening and flow rate is required, the backend maintenance key is clicked to activate the flow rate calibration module, and the real-time data acquisition module collects the pneumatic regulating valve opening and flow meter 4 flow rate data in real time under no-load conditions, recalibrates the flow rate, and saves it. Similarly, if the safe flow rate needs to be corrected, the safe flow rate setting key is clicked to set a new safe flow rate. If none of the above steps are necessary, it is determined whether a flow meter needs to be created or modified according to the current continuous casting steel grade, and if necessary, the backend maintenance key is clicked to activate the flow meter setting module and create or modify the flow meter. If not necessary, open the water meter selection dropdown list and the water distribution mode dropdown list, select the corresponding water meter and water distribution mode, and the real-time water distribution module will, according to the selected water meter and water distribution mode, distribute the pneumatic regulating valve opening at each casting speed water volume in real time via the PLC control system 9, accurately distribute the cooling water volume to the cooling system for controlling corner cracking of the slab, and store real-time data of the steel type, furnace number, casting speed, pneumatic regulating valve opening, flow meter 4 flow rate, and the current time of the system for each corresponding data acquisition cycle in a predetermined database.

[0067] According to the above-described slab narrow-face foot-roll type cooling system, parameters such as the type of microalloy to be produced, its slab cross-sectional dimensions, casting speed, and molten steel superheating degree are combined and, based on the casting speed of the continuous casting, the water volume of the first and second noise groups of the cooling system for controlling slab corner cracking, the water volume of the existing intermediate row of noise 10 circuits of the narrow-face foot-roll, and the water volume of the secondary cooling wide-face 1-4 zones are delivered online in real time.

[0068] For each of the aforementioned microalloy types and their continuous casting cross-sections and casting speeds, the method for determining the water volume of the first and second noise groups, the water volume of the 10 noise circuits in the existing intermediate row of the narrow-faced foot rolls, and the water volume of the 1-4 zones of the secondary cooling wide surface is shown below in the cooling system for controlling cracking at the corners of the slab, which involves spraying and strongly cooling the corners of the narrow faces of the inner and outer arches of the cast slab. This is determined by both computer numerical simulation calculations of the secondary cooling temperature field of the continuously cast slab and the grain refinement effect on the microstructure in the subcutaneous 0-10 mm range at the corners of the inner and outer arches of the cast slab, which has been prototyped on-site.

[0069] Furthermore, the existing intermediate row noise group includes 4 to 6 intermediate noises 10 distributed in the longitudinal direction of the microalloy steel slab to be continuously cast, with the centers of the 4 to 6 intermediate noises 10 lying on the same straight line. The narrow-face foot roll type cooling device includes a first noise group and a second noise group, the first and second noise groups provided on both sides of the existing intermediate row noise group of the narrow-face foot roll, with 4 to 6 first noises 11 evenly distributed along the direction of the casting speed of the microalloy steel slab to be continuously cast. The centers of the 4 to 6 first noises 11 of the first noise group lie on the same straight line, and the straight line in which the centers of the 4 to 6 first noises 11 of the first noise group are located is parallel to the straight line in which the centers of the intermediate noises 10 of the existing intermediate row noise group are located. The second noise group is located on the other side of the existing intermediate row noise group, with the centers of its 4 to 6 second noises 12 lying on the same straight line, and the straight line through which the centers of these 4 to 6 second noises 12 lie is parallel to the straight line through which the centers of the intermediate noises 10 of the existing intermediate row noise group lie. The first noises 11 of the 4 to 6 first noise groups and the second noises 12 of the 4 to 6 second noise groups are at the same height in pairs, with the highest-positioned first noises 11 of the first noise group and second noises 12 of the second noise group starting from the topmost or second-to-last intermediate noise 10 of the existing intermediate row noise group, the mounting height of each noise being the same as the height of the intermediate noise 10 of the existing intermediate row noise group at the corresponding height, and the distance between two adjacent first noises 11 of the first noise group being the same as the distance between two adjacent second noises 12 of the second noise group. The injection angle of the first noise 11 of the first noise group is 45° to 90°, the vertical height from the end of the first noise 11 to the surface of the narrow face of the cast slab is 40 to 100 mm, the extension line of each noise in the first noise group intersects with the corner of the narrow face of the corresponding cast slab, the injection angle of the second noise 12 of the second noise group is -45° to 90°, the vertical height from the end of the second noise 12 to the surface of the narrow face of the cast slab is 40 to 100 mm, the extension line of each noise in the second noise group intersects with the corner of the narrow face of the corresponding cast slab, and the effective width of the cooling water injected from the first noise 11 of the first noise group and the second noise 12 of the second noise group on the corner of the narrow face of the microalloy steel slab that is the target of continuous casting production is 30 to 60 mm.

[0070] The water supply piping 2 added within the frame 3 on the surface side of the narrow-face foot roll is independent of the water supply piping for the existing intermediate row of noise group members of the narrow-face foot roll. Two additional water channels 1 are added on both sides of the edge within the frame 3 on the surface side of the narrow-face foot roll, communicating with each other and running parallel to the side noise group members. The diameter of the two water channels 1 is generally 25 to 40 mm, and the maximum water flow rate of each water channel 1 is generally 100 L / min. Each water channel 1 extends from the bottom of the frame 3 on the surface side of the narrow-face foot roll until it is flush with the height of the uppermost or second-to-last side noise of the side noise group member. The positions of the two water channels 1 in the thickness direction of the cast slab are determined by the width of the frame 3 on the narrow-face foot roll surface side and the thickness of the continuous cast slab. The two water channels 1 of the frame 3 on the narrow-face foot roll surface side are connected to a first noise group and a second noise group that strongly cool the corners of the narrow faces of the inner and outer arches of the cast slab, and are designed to ensure a stable water supply to the first and second noise groups. The positions of the two water channels 1 added to the edges within the frame 3 relative to the foot roll surface side are such that the distance from the wall surface of the water channel 1 closest to the foot roll surface side to the edge of the frame 3 on the foot roll surface side is 5 to 30 mm. To connect the two water channels 1 added to the edges of the frame 3 on the surface side of the narrow-faced foot roll, an extension frame 3, 40 to 80 mm in length and with a cross-section the same as the bottom structure of the conventional narrow-faced foot roll surface frame 3, is sealed and welded to the lower part of the conventional narrow-faced foot roll surface frame 3. Holes are made laterally in the extension frame 3, and the two water channels 1 added to the edges of the frame 3 on the surface side of the narrow-faced foot roll are connected vertically. Alternatively, a water receiving section may be added separately to the frame 3 on the surface side of the narrow-faced foot roll corresponding to the water channel 1 added to each edge, and the two added water receiving sections may be joined and connected via a metal hose 7.A water receiving section added to the frame 3 on the surface side of the narrow foot roll is connected to an edge water channel 1 added within the frame 3 on the surface side of the narrow foot roll. These connectors have dimensions of DN40 or DN50 and are connected to a metal hose 7 near the water receiving section added to the frame 3 on the surface side of the narrow foot roll, which is laid from the vibrating frame 3 of the crystallizer to both sides of the crystallizer.

[0071] The spray structure added to the edge of the foot roll that strongly cools the corners of the narrow faces of the inner and outer arches of the cast slab consists of a first noise group and a second noise group. Both the first noise 11 and the second noise 12 are provided in 3 to 5 rows in the height direction of the narrow face foot roll, starting from the horizontal height of the first or second row above the existing intermediate row noise 10. Each row may be flush with the existing intermediate row noise 10, so that there are 3 noises in the lateral direction between each of the narrow face foot rolls. The inner diameter of the spray pipes 13 to which the first noise 11 and the second noise 12 are connected is all 12 to 20 mm, and the connection stage to the frame 3 on the surface side of the narrow face foot roll is fixed and connected to two water channels 1 inside the frame 3 on the surface side of the narrow face foot roll by screws or welding. Each spray tube 13 extends from the frame 3 on the surface side of the narrow-face foot roll, and then, depending on the thickness of the slab to be produced, the spray tubes 13 of the first noise 11 and the second noise 12 are designed to bend at a predetermined angle toward the corners of the narrow faces of the inner and outer arches of the slab, so that the axial extensions of the connecting ends of the first noise 11 and the second noise 12 intersect in a region of 0 to 20 mm from the corners of the narrow faces of the slab to the center of the narrow faces. This ensures that after bending, the axial extensions of the connecting ends of the first noise 11 and the second noise 12 intersect in a region of 0 to 20 mm from the corners of the narrow faces of the slab to the center of the narrow faces. The length of the spray tubes 13 corresponding to the first noise 11 and the second noise 12 is determined such that, when the bent spray tubes 13 are connected to the noise, the perpendicular distance from the narrow faces of the slab to either end of the first noise 11 and the second noise 12 is 40 to 100 mm. The screw structure of the spray tube 13 corresponding to the connection ends of the first noise 11 and the second noise 12 is designed according to the screw structure of the first noise 11 and the second noise 12, respectively.

[0072] The first noise 11 and second noise 12, which are structures that strongly spray the corners of the narrow faces of the inner and outer arches of the cast slab, are rectangular or conical noises cooled with pure water. In the case of a conical noise, the spray angle is 45 to 90°. In the case of a rectangular noise, the spray angle in the drawing direction and in the direction perpendicular to the rectangular noise is all 45 to 90°, and the effective width of the cooling water sprayed from the noise, from the corners of the narrow faces of the inner and outer arches of the cast slab to their centers, is ensured to be 30 to 60 mm, depending on the thickness of the cast slab, the bending angle of the spray pipe 13, and the distance from the end of the noise to the corners of the narrow faces of the cast slab.

[0073] Specific limitations on the cooling system for controlling corner cracking of microalloy steel slabs should be referred to above for limitations on the cooling method for controlling corner cracking of microalloy steel slabs, and will not be described in detail here. Each module of the above cooling system for controlling corner cracking of microalloy steel slabs is implemented by software, hardware, or a combination thereof. Each of the above modules may be embedded in the processor of an industrial computer device in hardware form or independent of the processor, or it may be stored in the memory of an industrial computer device as software and called by the processor to perform the operations corresponding to each of the above modules.

[0074] In one embodiment, an industrial computer device is provided, which may be a server with an internal structure diagram as shown in Figure 11. This industrial computer device includes a processor, memory, a network interface, and a database connected via a system bus. Of these, the processor of the industrial computer device provides computing and control capabilities. The memory of the industrial computer device may be a non-volatile and / or volatile storage medium, or internal memory. The non-volatile storage medium stores an operating system, computer programs, and a database. The internal memory provides an environment for the operating system and computer programs on the non-volatile storage medium to operate. The network interface of the industrial computer device connects to and communicates with external clients via a network. The computer program, when executed by the processor, implements server-side functions or steps of a cooling method for controlling corner cracking of a microalloy steel slab.

[0075] In one embodiment, an industrial computer device is provided, which may be a client whose internal structure is shown in Figure 12. The industrial computer device includes a processor, memory, a network interface, a display screen, and input devices connected via a system bus. The processor of the industrial computer device provides computing and control capabilities. The memory of the industrial computer device includes a non-volatile storage medium, internal memory. The non-volatile storage medium stores an operating system and computer programs. The internal memory provides an environment for the operating system and computer programs to run on the non-volatile storage medium. The network interface of the computer device communicates with an external server via a network. The computer program, when executed by the processor, implements client-side functions or steps of a cooling method for controlling corner cracking of a microalloy steel slab.

[0076] In one embodiment, the system includes a memory, a processor, and a computer program stored in the memory and operable by the processor, wherein the processor, upon execution of the computer program, determines the average cooling rate and minimum cooling temperature of the microstructure in the narrow-face foot roll strong cooling zone within a 0-10 mm subcutaneous range at the corners of a microalloy steel slab to be continuously cast, and the average temperature recovery rate in the wide-face 3 zone and wide-face 4 zone of the microstructure in the 0-10 mm subcutaneous range at the corners of the microalloy steel slab to be continuously cast, and wide-face 4 zone An industrial computer device is provided that enables the following steps: determining the temperature recovery temperature at the end of a zone; determining the amount of cooling water for the narrow-slab foot-roll type cooling device and the wide-slab zones 1 to 4 based on the average cooling rate, the minimum cooling temperature, the average temperature recovery rate in the wide-slab zone 3 and the wide-slab zone 4, and the temperature recovery temperature at the end of the wide-slab zone 4; and cooling the microalloy steel slab located within the secondary cooling zones 1 to 4 with the determined amount of cooling water for the narrow-slab foot-roll type cooling device and the wide-slab zones 1 to 4.

[0077] In one embodiment, an industrial computer-readable storage medium is provided that stores a computer program, and when the computer program is executed by a processor, it enables the following steps: determining the average cooling rate and minimum cooling temperature of the microstructure in the narrow-face foot-roll strong cooling zone of the microstructure in the 0-10 mm subsurface range of the corners of a microalloy steel slab to be continuously cast; determining the average temperature recovery rate in the wide-face 3 zone and wide-face 4 zone, and the temperature recovery temperature at the end of the wide-face 4 zone, of the microstructure in the 0-10 mm subsurface range of the corners of a microalloy steel slab to be continuously cast; determining the amount of cooling water for the slab narrow-face foot-roll type cooling device and wide-face 1-4 zones based on the average cooling rate and minimum cooling temperature, the average temperature recovery rate in the wide-face 3 zone and wide-face 4 zone, and the temperature recovery temperature at the end of the wide-face 4 zone; and cooling the microalloy steel slab located in the secondary cooling 1-4 zones with the determined amount of cooling water for the slab narrow-face foot-roll type cooling device and wide-face 1-4 zones.

[0078] For the sake of ease and conciseness of explanation, those skilled in the art will understand that in actual applications, the above functions may be performed by different functional units and modules as needed. That is, the internal structure of the device may be divided into different functional units or modules to perform all or part of the above functions.

[0079] The above embodiments are used solely to illustrate the technical solutions of the present invention and are not intended to limit them. While the present invention has been described in detail with reference to the above embodiments, those skilled in the art should understand that the technical solutions described in the above embodiments can be modified or some or all of their technical features can be replaced. Such modifications or replacements do not cause the essence of the corresponding technical solutions to deviate from the scope limited to the claims of the present invention. [Explanation of Symbols]

[0080] 1 Water Channel 2. Water supply piping 3. Narrow-width foot roll frame 4 Flow meter 5. Air pressure regulating valve 6. Shut-off valve 7 Additional water inlet 8 Industrial Computers 9 PLC control system 10 Existing intermediate column noise 11. First Noise 12. Second Noise 13 Spray pipe

Claims

1. 1. A cooling method for controlling corner cracking in microalloyed steel slabs, comprising: A step of determining an average cooling rate and a minimum cooling temperature in the intensive cooling zone of the narrow foot rolls for the structure within the range of 0 to 10 mm below the skin of the corner of the microalloy steel slab to be continuously cast, in order to transform the structure within the range of 0 to 10 mm below the skin of the corner of the microalloy steel slab from austenite to ferrite in the zone of the narrow foot rolls and disperse and precipitate microalloy carbonitrides; In order to completely re-austenitize the structure within a range of 0 to 10 mm beneath the corner of the microalloy steel slab by the time of the exit of the wide surface 4 zone, a step of determining the average temperature recovery rate in the wide surface 3 zone and the wide surface 4 zone and the temperature recovery temperature at the end of the wide surface 4 zone for the structure within a range of 0 to 10 mm beneath the corner of the microalloy steel slab to be produced by continuous casting; determining the amounts of cooling water for the narrow-face foot roll type cooling device and the wide-face zones 1 to 4 based on the average cooling rate and minimum cooling temperature, the average temperature recovery rate in the wide-face zone 3 and the wide-face zone 4, and the temperature recovery temperature at the end of the wide-face zone 4; and cooling the microalloy steel slab located in secondary cooling zones 1 to 4 using the determined narrow face foot roll type cooling device and the determined cooling water amounts for zones 1 to 4 of the wide faces.

2. Obtaining parameters of the continuous casting process of the micro-alloy steel slab to be produced by continuous casting; According to the parameters of the continuous casting process, using commercial finite element software or self-programming, create a three-dimensional unsteady temperature field calculation model of the continuously cast slab, including the crystallizer and the secondary cooling 1 to 4 zone stages, and calculate the temperature field distribution of the micro-alloy steel slab to be continuously cast; The method further includes the steps of: determining, from the calculated temperature field distribution of the micro-alloy steel slab, the average cooling rate and minimum cooling temperature in the narrow side foot roll zone of the structure within a range of 0 to 10 mm below the skin of the corner of the micro-alloy steel slab to be produced by continuous casting; and determining, from the calculated temperature field distribution of the micro-alloy steel slab, the average temperature recovery rate in the wide side 3 zone and the wide side 4 zone of the structure within a range of 0 to 10 mm below the skin of the corner of the micro-alloy steel slab to be produced by continuous casting, and the temperature recovery temperature at the end of the wide side 4 zone; 2. The cooling method according to claim 1, wherein the parameters of the continuous casting process include a cross-sectional size of the slab, a casting speed, a superheat of the molten steel of the micro-alloy steel slab to be produced by continuous casting, a cooling water amount and a water temperature difference on the wide surface of the crystallizer, and a cooling water amount and a water temperature difference on the narrow surface of the crystallizer.

3. The cooling method according to claim 2, wherein the cross-sectional dimensions of the slab are 2100 mm x 250 mm, the casting speed is 0.8 to 1.3 m / min, the molten steel superheat of the micro-alloy steel plate to be produced by continuous casting is 25°C, the cooling water flow rate on the wide surface of the crystallizer is 3250 L / min, the water temperature difference is 7.5°C, and the cooling water flow rate on the narrow surface of the crystallizer is 390 L / min, the water temperature difference is 8.2°C.

4. The cooling method according to claim 2, characterized in that the structure within a range of 0 to 10 mm below the skin of the corners of the micro-alloy steel slab to be produced by continuous casting has an average cooling rate of 5°C / s or more and a minimum cooling temperature of 550 to 600°C in the strong cooling zone of the narrow face foot roll, an average temperature recovery rate of 3.5°C / s or more in the wide face 3 zone and the wide face 4 zone, and a temperature recovery temperature of 900°C or more at the end of the wide face 4 zone.

5. 1. A cooling system for controlling corner cracking in microalloyed steel slabs, comprising: a first parameter determination module for determining an average cooling rate and a minimum cooling temperature in the intensive cooling zone of the narrow foot rolls for the structure within a range of 0 to 10 mm below the skin of the corner of the microalloy steel slab to be continuously cast, in order to transform the structure within a range of 0 to 10 mm below the skin of the corner of the microalloy steel slab from austenite to ferrite in the narrow foot roll zone and disperse and precipitate microalloy carbonitrides; a second parameter determination module for determining an average temperature recovery rate in the wide surface 3 zone and the wide surface 4 zone and a temperature recovery temperature at an end of the wide surface 4 zone for the structure within the range of 0 to 10 mm below the skin of the corner of the microalloy steel slab to be continuously cast and to completely re-austenitize the structure within the range of 0 to 10 mm below the skin of the corner of the microalloy steel slab by the exit of the wide surface 4 zone; a third parameter determination module that determines the amounts of cooling water for the narrow-face foot roll type cooling device and the wide-face zones 1 to 4 based on the average cooling rate and minimum cooling temperature, the average temperature recovery rate in the wide-face zone 3 and the wide-face zone 4, and the temperature recovery temperature at an end of the wide-face zone 4; and A cooling system comprising: a cooling module that cools a micro-alloy steel slab located in secondary cooling zones 1 to 4 using the determined narrow face foot roll type cooling device and cooling water amounts for the wide face zones 1 to 4.

6. The narrow-face foot roll type cooling device is a first noise group provided on the frame edge portion on the surface side of the narrow-face foot roll and communicating with the water channel; a second noise group provided on the edge of the other side of the frame on the surface side of the narrow-faced foot roll, the second noise group being symmetrical in width to the frame of the first noise group on the surface side of the narrow-faced foot roll; The water channels are provided in the frame of the narrow-faced foot roll and communicate with the first noise group and the second noise group, respectively; 6. The cooling system of claim 5, further comprising: a water supply pipe connected to the water channel and provided with a flow meter, an air pressure regulating valve, and a shut-off valve, the flow meter, the air pressure regulating valve, and the shut-off valve being electrically connected to the cooling module, the cooling module turning on the shut-off valve according to the water volume of the narrow-faced foot roll type cooling device determined by the cooling module, and controlling the degree of opening of the air pressure regulating valve according to the flow rate of the water supply pipe detected by the flow meter.

7. The narrow-faced foot roll cooling device further includes an industrial computer, a human-machine interaction interface, and a PLC control system, wherein the industrial computer, the flow meter, and the air pressure regulating valve are connected to the PLC control system via cables, the industrial computer is communicatively connected to the PLC control system, and the human-machine interaction interface is attached to the industrial computer, and includes a system maintenance backend and a real-time operating status information display / operation front-end interface, wherein the system maintenance backend includes a data communication module, a data real-time collection module, a water meter setting module, a flow rate calibration module, a water volume real-time distribution module, a data storage module, and a historical data query module; a data communication module that connects the industrial computer and the PLC control system so as to be able to communicate with each other in real time and displays a current communication status between the industrial computer and the PLC control system; The real-time data collection module collects in real time data on the steel type, furnace number, casting speed, air pressure control valve opening, and flow meter flow rate of the micro-alloy steel slab to be continuously cast; The water meter setting module has the function of creating, modifying and saving water meters. The real-time water volume distribution module distributes the cooling water volume that matches the current casting speed according to the water meter and water volume distribution mode selected through the real-time operating status information display / operation front-end interface; The data storage module stores the steel type, furnace number, casting speed, air pressure regulating valve opening, flow meter flow rate, and current real-time data of the system corresponding to the data collection period in a predetermined database; The cooling system of claim 5, wherein the historical data query module calls the data storage database and extracts the data to be queried based on the data query method and data query range selected by the real-time operating status information display / operation front-end interface.

8. The first noise group and the second noise group are provided on both sides of the existing intermediate row noise group of the narrow face foot roll, and 4 to 6 noises are evenly provided along the direction of the casting speed of the micro-alloy steel slab to be produced by continuous casting, and the centers of the 4 to 6 noises of the first noise group are on the same straight line, and the line on which the centers of the 4 to 6 noises of the first noise group are located is parallel to the line on which the centers of the noises of the existing intermediate row noise group are located, and the second noise group is located on the other side of the existing intermediate row noise group, and the centers of the 4 to 6 noises of the second noise group are on the same straight line, and the 4 to 6 noises of the second noise group are a line on which the centers of the noises of the group are located is parallel to a line on which the centers of the noises of the noise group of the existing intermediate row are located, the four to six noises of the first noise group and the four to six noises of the second noise group have the same height, the highest noises of the first noise group and the highest noises of the second noise group start from the top or second noise of the noise group of the existing intermediate row, the installation height of each noise is the same as the height of the noise of the noise group of the existing intermediate row at the corresponding height, the distance between two adjacent noises of the first noise group is the same as the distance between two adjacent noises of the second noise group, 7. The cooling system of claim 6, wherein the nozzles of the first group have an injection angle of 45° to 90°, a vertical height from the nozzle end to the surface of the narrow side of the slab is 40 to 100 mm, an axial extension line of each nozzle of the group intersects with a corner of the corresponding narrow side of the slab, the nozzles of the second group have an injection angle of -45° to -90°, a vertical height from the nozzle end to the surface of the narrow side of the slab is 40 to 100 mm, an axial extension line of each nozzle of the group intersects with a corner of the corresponding narrow side of the slab, and the acting width of the cooling water sprayed from the nozzles of the first group and the nozzles of the second group against the corner of the narrow side of the micro-alloy steel slab to be produced by continuous casting is 30 to 60 mm from the corner toward the center of the narrow side.

9. 1. An industrial computing device including a memory, a processor, and a computer program stored in the memory and operable on the processor, An industrial computer device characterized in that, when the processor executes the computer program, it realizes the steps of the cooling method for controlling corner cracking of micro-alloy steel slabs described in any one of claims 1 to 4.

10. An industrial computer-readable storage medium storing a computer program, comprising: An industrial computer-readable storage medium, characterized in that, when the computer program is executed by a processor, it realizes the steps of the cooling method for controlling corner cracking of micro-alloyed steel slabs described in any one of claims 1 to 4.

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