CN113102714B - Continuous casting cooling method for controlling peritectic steel slab corner cracks - Google Patents
Continuous casting cooling method for controlling peritectic steel slab corner cracks Download PDFInfo
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- B22—CASTING; POWDER METALLURGY
- B22D—CASTING OF METALS; CASTING OF OTHER SUBSTANCES BY THE SAME PROCESSES OR DEVICES
- B22D11/00—Continuous casting of metals, i.e. casting in indefinite lengths
- B22D11/16—Controlling or regulating processes or operations
- B22D11/22—Controlling or regulating processes or operations for cooling cast stock or mould
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- B—PERFORMING OPERATIONS; TRANSPORTING
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- B22D—CASTING OF METALS; CASTING OF OTHER SUBSTANCES BY THE SAME PROCESSES OR DEVICES
- B22D11/00—Continuous casting of metals, i.e. casting in indefinite lengths
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- B22D11/124—Accessories for subsequent treating or working cast stock in situ for cooling
- B22D11/1245—Accessories for subsequent treating or working cast stock in situ for cooling using specific cooling agents
Abstract
The invention provides a continuous casting cooling method for controlling peritectic steel slab corner cracks, which relates to the technical field of steel metallurgy continuous casting, can eliminate peritectic steel slab corner cracks, does not generate other surface crack defects, and effectively improves the quality of peritectic steel continuous casting billets; the method comprises the following steps: 1) controlling the energy-speed ratio C of the crystallizer in the crystallization process to be unchanged; 2) the ratio of the water amount of each section of the secondary cooling area to the total water amount of the secondary cooling area is as follows: 27-29% of a foot roller section, 35-37% of a bending section, 14-15% of a fan-shaped section 1, 8-9% of a fan-shaped section 2 and 9-10% of a fan-shaped section 3-4; the pulling speed is less than or equal to 1.1m/min, and the fan-shaped sections of 5-9 do not spray; the pulling speed is more than or equal to 1.1m/min, the fan shape is 2-3% in 5-6 sections, and the rest sections are not sprayed; the pulling speed is more than or equal to 1.3m/min, and the segment of 7-9 sectors is 2-3%; the fan-shaped section is not sprayed in the area 100mm away from the edge of the casting blank. The technical scheme provided by the invention is suitable for the steel continuous casting cooling process.
Description
[ technical field ] A method for producing a semiconductor device
The invention relates to the technical field of steel metallurgy continuous casting, in particular to a continuous casting cooling method for controlling peritectic steel slab corner cracks.
[ background of the invention ]
The cracks at the corners of the continuous casting slabs mostly start from the crystallizer and then spread at the secondary cooling zone and the straightening point, and finally form surface cracks. When peritectic steel is produced, peritectic reaction occurs in the crystallizer, the linear shrinkage in the solidification process is large, the heat flow in the crystallizer is easily distributed unevenly, the thickness of a blank shell is uneven, and slab cracks are generated. In addition, in the straightening process of the continuous casting blank, the temperature of the corner of the casting blank enters a third brittleness temperature area, and the corner crack of the casting blank is further expanded and aggravated under the dual effects of crystal boundary weakening and vibration mark notch effect.
In order to solve the problem of casting peritectic steel cracks, the prior art method properly reduces the cooling strength of a crystallizer and adopts a weak cooling system in a secondary cooling area to avoid the expansion of the cracks. The defects that the water quantity adjustment of the crystallizer is not related to the dynamic change of the water temperature difference of the inlet and the outlet of the cooling water, and the difference between the actual application effect and the simulation result is large; the secondary cooling area adopts weak cooling to cause the bulging phenomenon of the casting blank, thereby reducing the quality of the continuous casting blank; the water quantity adjustment of the secondary cooling area is influenced by the arrangement mode of nozzles of the continuous casting machine, and the actual effect is limited.
The invention patent of application publication No. CN 106735035A, entitled "a method for reducing slab cracking", proposes a method for reducing slab cracking by reducing water flow rate of a nozzle at a corner of a casting slab to make the temperature of the corner of the casting slab higher than the brittle temperature range thereof. The method does not consider the influence of the cooling of a casting blank crystallizer on the surface quality of a casting blank, and the improvement of the corner temperature of the casting blank by reducing the water spraying quantity of the corner of the casting blank is limited or is not enough to avoid a third brittle temperature interval of the casting steel grade.
The invention patent of application publication No. CN 106825478B, entitled "method for controlling corner cracks of boron-containing steel plate blank", provides a quantitative relation between water quantities of a crystallizer and a secondary cooling area and a product of the section size of a casting blank and a pulling speed, so as to control water distribution quantities of casting blank crystallizers and secondary cooling sections with different sizes and further control corner cracks of the boron-containing steel plate blank. The method does not consider the influence of the change of the temperature difference of the inlet/outlet water of the cooling water of the crystallizer on the cooling of the crystallizer, and the secondary cooling area adopts a full-coverage spraying mode, which is not beneficial to improving the corner temperature of the casting blank.
Accordingly, there is a need to develop a continuous casting cooling method for controlling cracks at corners of peritectic steel slabs to overcome the shortcomings of the prior art, and to solve or alleviate one or more of the problems described above.
[ summary of the invention ]
In view of the above, the invention provides a continuous casting cooling method for controlling peritectic steel slab corner cracks, which can eliminate peritectic steel slab corner cracks, simultaneously does not generate other surface crack defects, and effectively improves the quality of peritectic steel continuous casting billets.
In one aspect, the present invention provides a continuous casting cooling method for controlling cracks at corners of a peritectic steel slab, the method comprising:
1) controlling the energy-speed ratio C of the crystallizer in the crystallization process to be unchanged;
the energy speed ratio C is specifically as follows:
in the formula, omega is a correction coefficient, W is the cooling water quantity of the wide/narrow face of the crystallizer, delta T is the water temperature difference of the inlet and outlet of the cooling water of the wide/narrow face of the crystallizer, and v is the pulling speed of the peritectic steel plate blank;
the energy speed ratio C in the actual crystallization process is consistent with the simulated C value, and the simulated C value is the energy speed ratio when the thickness of the casting blank shell at the outlet of the crystallizer reaches 15 mm;
2) the percentage of the cooling water amount of each cooling section of the second cooling area to the total cooling water amount of the second cooling area is as follows: the foot roller section accounts for 27% -29%, the bending section accounts for 35% -37%, the sector 1 section accounts for 14% -15%, the sector 2 section accounts for 8% -9%, and the sector 3-4 section accounts for 9% -10%; when the pulling speed is less than or equal to 1.1m/min, the fan-shaped sections 5-9 are not subjected to spray cooling; when the pulling speed is more than or equal to 1.1m/min, the sector 5-6 sections account for 2% -3%, and the rest cooling sections do not carry out spray cooling; when the pulling speed is more than or equal to 1.3m/min, the sector 7-9 sections account for 2-3 percent.
In accordance with one aspect of the present invention and any one of the possible implementations thereof, there is further provided an implementation where the correction coefficient ω is 1 × 10-3m/(L ℃.); the pulling speed of the peritectic steel slab is 0.8-1.4 m/min.
The above aspect and any possible implementation manner further provide an implementation manner, and the content of the continuous casting cooling method further includes: 3) and the foot roll section and the bending section of the secondary cooling area adopt a full-coverage spraying mode, and the nozzle distance of the fan-shaped section is adjusted, so that the continuous casting blank is not covered by spraying water in a region with the width of 100mm from the edge of the casting blank in the fan-shaped section.
The above aspect and any possible implementation manner further provide an implementation manner that the specific water amount in the secondary cooling zone is 0.53-0.68L/Kg, and the specific water amount is 0.25v +0.33, and v is the drawing speed of the continuous casting machine.
The above aspects and any possible implementation manners further provide an implementation manner that the percentage of the cooling water amount of the wide and narrow sides of the foot roller section to the total cooling water amount of the two cooling areas is 22% -24% and 4% -5%, respectively.
The above aspect and any possible implementation manner further provide an implementation manner that the ratio of the cooling water amount at the upper part of the bending section is 20% -21%, and the ratio of the cooling water amount at the lower part of the bending section is 15% -16%.
The above-mentioned aspects and any possible implementation manner further provide an implementation manner that the sectional dimension of the peritectic steel slab is (1020 × 200) mm to (1120 × 200) mm.
The above aspects and any possible implementations further provide an implementation in which the two-cooling zone foot roll section employs water nozzles, and the remaining cooling zones employ gas-mist nozzles; the narrow sides of the casting blank are only provided with water nozzles at the foot roll sections, and the other cooling sections are air-cooled.
In the aspect and any possible implementation manner described above, there is further provided an implementation manner, wherein the ratio of water distribution in the inner arc and water distribution in the outer arc of each cooling section in the second cooling zone is: 1:1 of foot roller section, bending section: 1:1, segment 1: 1:1.2, sector 2 section 1:1.25, sector 3-4 sections: 1:1.35, 5-6 segments of a sector, 1:1.4, 7-9 segments of a sector: 1:1.5.
The above aspects and any possible implementation manner further provide an implementation manner that the superheat degree of the peritectic steel during casting is 30-40 ℃.
Compared with the prior art, the invention can obtain the following technical effects: 1) the invention controls the cooling water quantity of the crystallizer in real time through the water inlet/outlet water temperature difference of the cooling water of the crystallizer and the pulling speed, and ensures that the cooling strength of the crystallizer is maintained in a stable weak cooling state in the peritectic steel continuous casting slab process, thereby improving the thickness uniformity of a primary blank shell and reducing the probability of forming primary cracks in the crystallizer; 2) in the process of designing the water amount of the secondary cooling area, the invention is combined with the adjustment of the nozzle arrangement mode, the problem of bulging of the casting blank caused by weak cooling of the traditional secondary cooling area is avoided while the temperature of the corner of the casting blank in the straightening area is ensured to be higher than the upper limit of the third brittle temperature area of the cast steel, the surface temperature of the casting blank is uniformly distributed along the width direction, the temperature fluctuation along the blank drawing direction is smaller, the longitudinal-transverse cooling uniformity of the casting blank is improved, the quality of the casting blank is obviously improved, and the production efficiency is improved.
Of course, it is not necessary for any one product in which the invention is practiced to achieve all of the above-described technical effects simultaneously.
[ description of the drawings ]
In order to more clearly illustrate the technical solutions of the embodiments of the present invention, the drawings needed to be used in the embodiments will be briefly described below, and it is obvious that the drawings in the following description are only some embodiments of the present invention, and it is obvious for those skilled in the art to obtain other drawings based on these drawings without creative efforts.
FIG. 1 is a sectional view of a secondary cooling zone of a continuous casting machine according to an embodiment of the present invention.
Wherein, in the figure:
1-foot roller section, 2-bending section upper part, 3-bending section lower part, 4-12-sector 1-9 sections.
[ detailed description ] embodiments
For better understanding of the technical solutions of the present invention, the following detailed descriptions of the embodiments of the present invention are provided with reference to the accompanying drawings.
It should be understood that the described embodiments are only some embodiments of the invention, and not all embodiments. All other embodiments, which can be derived by a person skilled in the art from the embodiments given herein without making any creative effort, shall fall within the protection scope of the present invention.
The terminology used in the embodiments of the invention is for the purpose of describing particular embodiments only and is not intended to be limiting of the invention. As used in the examples of the present invention and the appended claims, the singular forms "a," "an," and "the" are intended to include the plural forms as well, unless the context clearly indicates otherwise.
Based on the simulation research of the solidification heat transfer value of the continuous casting slab, the invention designs and optimizes the parameters of crystallizer cooling, secondary cooling of a continuous casting machine and the distance between nozzles of a secondary cooling fan-shaped section, improves the longitudinal-transverse cooling uniformity of the continuous casting slab, aims to eliminate the corner cracks of the peritectic steel continuous casting slab and simultaneously does not generate other surface defects, thereby improving the quality of the peritectic steel continuous casting slab.
The contents of the continuous casting cooling technology for controlling the peritectic steel slab corner cracks comprise:
(1) a plate blank continuous casting solidification heat transfer mathematical model is established, water consumption of a continuous casting blank wide/narrow surface at a crystallizer outlet when the thickness of a casting blank shell reaches 15mm is respectively obtained through simulation calculation, and a calculation formula of a ratio C (called an energy speed ratio in the application) of a product of cooling water quantity of the wide/narrow surface of the crystallizer and a temperature difference of cooling water inlet/outlet water and a pulling speed is as follows:
where ω is a correction coefficient, and the unit is m/(L · ° c), ω is 1 × 10-3；W0The water amount of the wide/narrow surface of the crystallizer is L/min; delta T0The initial water temperature difference, DEG C, v, of the wide/narrow face cooling water inlet/outlet of the crystallizer0The initial drawing speed of the continuous casting machine is m/min.
The wide/narrow surface water amount of the continuous casting billet and the crystallizer refers to the total amount of wide surface cooling water and narrow surface cooling water.
Determining the C value of the wide/narrow surface of the crystallizer under different continuous casting billet section sizes through simulation calculation, and in actual production, according to a combination formula of casting machine pulling speed and corresponding crystallizer wide/narrow surface inlet/outlet water temperature difference values in the pouring process
The water amount of the wide/narrow surface of the crystallizer is regulated and controlled in real time, so that the C value in actual production is consistent with the simulation calculation result, and the C value is kept unchanged in the cooling process. Where ω is a correction coefficient, m/(L · ° c), ω is 1 × 10-3(ii) a W is the water amount of the wide/narrow surface of the crystallizer, and L/min; delta T is the temperature difference of water at the inlet/outlet of cooling water on the wide/narrow surface of the crystallizer, DEG C, v is the drawing speed of the continuous casting machine, and m/min.
(2) The percentage of the water distribution amount of each cooling section of the secondary cooling area to the total water amount of the secondary cooling area is as follows: the foot roll section accounts for 27% -29%, the bending section accounts for 35% -37%, the sector 1 section accounts for 14% -15%, the sector 2 section accounts for 8% -9%, and the sector 3-4 section accounts for 9% -10%, when the pulling speed is less than or equal to 1.1m/min, the sector 5-9 sections do not carry out spray cooling, when the pulling speed is greater than or equal to 1.1m/min, the sector 5-6 sections account for 2% -3%, the rest cooling sections do not carry out spray cooling, when the pulling speed is greater than or equal to 1.3m/min, the sector 7-9 sections account for 2% -3%.
(3) And the foot roll section and the bending section of the secondary cooling area adopt a full-coverage spraying mode, and the nozzle distance of the fan-shaped section is adjusted, so that the continuous casting blank is not covered by spraying water in a region with the width of 100mm from the edge of the casting blank in the fan-shaped section.
The specific water amount of the secondary cooling zone is 0.53-0.68L/Kg, the specific water amount and the continuous casting billet drawing speed are in a linear relation, and the calculation formula is as follows:
w＝0.25λv+0.33
wherein w is the specific water amount, L/Kg; λ is a correction coefficient, L · min/(Kg · m), and λ is taken as 1; v is the drawing speed of the continuous casting machine, m/min.
The percentage of the water amount of the wide and narrow side of the foot roller section in the total water amount of the secondary cooling area is 22-24% and 4-5% respectively.
The water content of the upper part of the bending section is 20-21%, and the water content of the lower part of the bending section is 15-16%. The second cooling zone foot roller section adopts a water nozzle, and the other cooling zones adopt an air-mist nozzle; the narrow sides of the casting blank are only provided with water nozzles at the foot roll sections, and the other cooling sections are air-cooled.
The water distribution ratio of the inner arc and the outer arc of each cooling section of the second cooling area is as follows: 1:1 of foot roller section, bending section: 1:1, segment 1: 1:1.2, sector 2 section 1:1.25, sector 3-4 sections: 1:1.35, 5-6 segments of a sector, 1:1.4, 7-9 segments of a sector: 1:1.5.
The pulling speed of the peritectic steel continuous casting slab is 0.8-1.4 m/min. The sectional dimension of the peritectic steel slab is (1020 multiplied by 200) mm to (1120 multiplied by 200) mm. The superheat degree of peritectic steel during casting is 30-40 ℃.
The invention can effectively solve two problems in the continuous casting production process by controlling the method that the ratio of the product of the cooling water quantity of the wide/narrow surface of the crystallizer and the water temperature difference of the cooling water inlet and the cooling water outlet to the casting speed is not changed:
1) when peritectic steel is cast, the water distribution amount of the crystallizer is not matched with the pulling speed of the continuous casting billet, so that the cooling strength of the crystallizer is larger or smaller, the cooling strength of the crystallizer is smaller or larger, the cooling shrinkage of the continuous casting billet in the primary billet shell of the meniscus area of the crystallizer is increased, the uneven cooling of the continuous casting billet in the crystallizer is intensified, the uniform growth of the solidified billet shell is not facilitated, and the surface crack occurrence probability is improved; the latter can cause that the thickness of the billet shell of the continuous casting billet at the outlet of the crystallizer cannot meet the requirement of the thickness of the safe billet shell (more than or equal to 15mm), thereby increasing the risk of steel leakage;
2) in the casting process, the temperature difference of the cooling water inlet/outlet of the crystallizer at different time and under different working conditions is fluctuated, and the water distribution amount of the crystallizer is not correspondingly adjusted, so that the cooling intensity of the crystallizer is changed, the quality of a primary blank shell of a continuous casting billet is influenced, and the quality of the continuous casting billet cannot be stably and effectively controlled.
The invention designs and optimizes the water content ratio of each section of the secondary cooling zone, controls the water content ratio of the wide surface of the foot roll section to be 27-29%, and avoids the generation of large temperature return after the continuous casting billet is discharged out of a crystallizer while increasing the strength of the continuous casting billet so as to induce surface cracks. The water content of the upper part of the bending section is controlled to be 20-21%, and the water content of the lower part of the bending section is controlled to be 15-16%, so that the longitudinal cooling uniformity of the continuous casting blank can be improved, and meanwhile, the surface temperature of the casting blank is further reduced, and the bulging of the casting blank is prevented. The water ratio of the segment 1 is controlled to be 14% -15%, the segment 2 is controlled to be 8% -9%, and the segment 3-4 is controlled to be 9% -10%, so that the longitudinal cooling uniformity of the continuous casting billet is guaranteed while weak cooling is adopted, and the improvement of the corner temperature of the continuous casting billet is facilitated. The water content of the narrow surface of the foot roll section is controlled to be 4-5%, the narrow surface of the continuous casting billet in other cooling sections is air-cooled, the continuous casting billet is air-cooled in a straightening area (a fan-shaped 6 section) when the drawing speed is less than or equal to 1.1m/min, a small amount of water is distributed when the drawing speed is more than or equal to 1.1m/min, and the like, so that the corner temperature of the continuous casting billet can be further improved, the continuous casting billet is ensured to have good plasticity in the straightening area, and corner cracks are avoided.
The existing technical method adopting a weak cooling system in the secondary cooling area inevitably increases the bulging occurrence probability of the continuous casting billet. According to the invention, by adjusting the distance between the nozzles of the two cooling fan-shaped sections, the continuous casting blank is not covered by spray water in the area of the fan-shaped section 100mm away from the edge of the casting blank, so that the corner temperature of the continuous casting blank is further increased, and the defect of corner crack is favorably eliminated. Meanwhile, the method increases the spraying overlapping area between adjacent nozzles, improves the cooling strength of the central area of the wide surface of the continuous casting billet, enables the cooling strength to be maintained below 1100 ℃, and can effectively prevent the casting billet from bulging.
The partition segmentation relating to the secondary cooling zone in the embodiments of the present invention is shown in table 1:
TABLE 1
Example 1:
the method is adopted for peritectic steel continuous casting slabs with the thickness of 200mm multiplied by 1020mm, the steel grade is Q235B, the casting temperature is 1560 ℃, and the drawing speed is 0.9 m/min.
1) Establishing a plate blank continuous casting solidification heat transfer mathematical model, and obtaining through simulation calculation: under the section size of the continuous casting billet, the corresponding C value of the wide surface of the crystallizer is C1The narrow face of the crystallizer corresponds to the value C of 16.0422.75, in the production process, according to the combination formula of water temperature difference values of wide/narrow face inlet and outlet of crystallizer under the pulling speed
Regulating and controlling the water amount of the wide/narrow surface of the crystallizer in real time to ensure that the C value corresponding to the wide/narrow surface of the crystallizer in actual production and a simulation calculation result C1、C2The values are in agreement with each other,
2) controlling the specific water amount of the secondary cooling area of the continuous casting to be 0.56L/Kg, wherein the percentage of the water distribution amount of each cooling section of the secondary cooling area to the total water amount of the secondary cooling area is respectively as follows: the wide surface of the foot roll section accounts for 24 percent, the narrow surface of the foot roll section accounts for 5 percent, the upper part of the bending section accounts for 21 percent, the lower part of the bending section accounts for 16 percent, the segment 1 of the sector accounts for 15 percent, the segment 2 of the sector accounts for 9 percent, the segments 3 to 4 of the sector account for 10 percent, the segments 5 to 9 of the sector are air-cooled,
3) the arrangement mode of the nozzles of the secondary cooling fan-shaped section is 2-2-2 arrangement mode, the distance between the nozzles is regulated to be 300mm, and the continuous casting blank is not covered by spray water in the area of the fan-shaped section 100mm away from the edge of the casting blank.
The industrial test result shows that the corner crack defect of the continuous casting billet disappears, no other crack defects are generated on the surface of the continuous casting billet, and the quality of the continuous casting billet is higher.
Example 2:
the method is adopted for peritectic steel continuous casting slabs with the thickness of 200mm multiplied by 1020mm, the steel grade is Q235B, the casting temperature is 1560 ℃, the drawing speed is 1.1m/min,
1) establishing a plate blank continuous casting solidification heat transfer mathematical model, and obtaining through simulation calculation: under the section size of the continuous casting billet, the corresponding C value of the wide surface of the crystallizer is C1The narrow face of the crystallizer corresponds to the value C of 16.0422.75, in the production process, according to the combination formula of water temperature difference values of wide/narrow face inlet and outlet of crystallizer under the pulling speed
Regulating and controlling the water amount of the wide/narrow surface of the crystallizer in real time to ensure that the C value corresponding to the wide/narrow surface of the crystallizer in actual production and a simulation calculation result C1、C2The values are in agreement with each other,
2) controlling the specific water amount of the secondary cooling area of the continuous casting to be 0.61L/Kg, wherein the percentage of the water distribution amount of each cooling section of the secondary cooling area to the total water amount of the secondary cooling area is respectively as follows: the width of the foot roller section accounts for 23%, the narrow surface of the foot roller section accounts for 5%, the upper part of the bending section accounts for 21%, the lower part of the bending section accounts for 15%, the segment 1 accounts for 15%, the segment 2 accounts for 9%, the segments 3-4 account for 10%, the segments 5-6 account for 2%, the segments 7-9 are air-cooled,
3) the arrangement mode of the nozzles of the secondary cooling fan-shaped section is 2-2-2 arrangement mode, the distance between the nozzles is regulated to be 300mm, and the continuous casting blank is not covered by spray water in the area of the fan-shaped section 100mm away from the edge of the casting blank.
The industrial test result shows that the corner crack defect of the continuous casting billet disappears, no other crack defects are generated on the surface of the continuous casting billet, and the quality of the continuous casting billet is higher.
Example 3:
the method is adopted for peritectic steel continuous casting slabs with the thickness of 200mm multiplied by 1020mm, the steel grade is Q235B, the casting temperature is 1560 ℃, the drawing speed is 1.4m/min,
1) establishing a plate blank continuous casting solidification heat transfer mathematical model, and obtaining through simulation calculation: under the section size of the continuous casting billet, the corresponding C value of the wide surface of the crystallizer is C1The narrow face of the crystallizer corresponds to the value C of 16.0422.75, in the production process, according to the combination formula of water temperature difference values of wide/narrow face inlet and outlet of crystallizer under the pulling speed
Regulating and controlling the water amount of the wide/narrow surface of the crystallizer in real time to ensure that the C value corresponding to the wide/narrow surface of the crystallizer in actual production and a simulation calculation result C1、C2The values are identical.
2) Controlling the specific water amount of the secondary cooling area of the continuous casting to be 0.68L/Kg, wherein the percentage of the water distribution amount of each cooling section of the secondary cooling area to the total water amount of the secondary cooling area is respectively as follows: the wide surface of the foot roller section accounts for 23%, the narrow surface of the foot roller section accounts for 5%, the upper part of the bending section accounts for 20%, the lower part of the bending section accounts for 15%, the segment 1 accounts for 14%, the segment 2 accounts for 9%, the segment 3-4 accounts for 9%, the segment 5-6 accounts for 3%, and the segment 7-9 accounts for 2%.
3) The arrangement mode of the nozzles of the secondary cooling fan-shaped section is 2-2-2 arrangement mode, the distance between the nozzles is regulated to be 300mm, and the continuous casting blank is not covered by spray water in the area of the fan-shaped section 100mm away from the edge of the casting blank.
The industrial test result shows that the corner crack defect of the continuous casting billet disappears, no other crack defects are generated on the surface of the continuous casting billet, and the quality of the continuous casting billet is higher.
Comparative example 1:
the method is adopted for peritectic steel continuous casting slabs with the thickness of 200mm multiplied by 1020mm, the steel grade is Q235B, the casting temperature is 1560 ℃, the drawing speed is 0.9m/min,
1) the water distribution of the wide surface and the water distribution of the narrow surface of the crystallizer are controlled to be 2685L/min and 465L/min, and the water distribution of the wide surface and the narrow surface of the crystallizer is kept unchanged in the continuous casting process.
2) Controlling the specific water amount of the secondary cooling area of the continuous casting to be 0.55L/Kg, wherein the percentage of the water distribution amount of each cooling section of the secondary cooling area to the total water amount of the secondary cooling area is respectively as follows: the wide surface of the foot roll section accounts for 24%, the narrow surface of the foot roll section accounts for 5%, the upper part of the bending section accounts for 21%, the lower part of the bending section accounts for 16%, the section 1 of the sector accounts for 15%, the section 2 of the sector accounts for 9%, the section 3-4 of the sector accounts for 10%, and the section 5-9 of the sector is air-cooled.
3) The arrangement mode of the nozzles of the secondary cooling fan-shaped section is 2-2-2 arrangement mode, the distance between the nozzles is regulated to be 300mm, and the continuous casting blank is not covered by spray water in the area of the fan-shaped section 100mm away from the edge of the casting blank.
The industrial test result shows that the corner crack defect of the continuous casting billet is obviously improved, but a large number of fine longitudinal cracks are distributed on the wide surface of the continuous casting billet, and the quality of the continuous casting billet is lower.
Comparative example 2:
the method is adopted for peritectic steel continuous casting slabs with the thickness of 200mm multiplied by 1020mm, the steel grade is Q235B, the casting temperature is 1560 ℃, the drawing speed is 0.9m/min,
1) establishing a plate blank continuous casting solidification heat transfer mathematical model, and obtaining through simulation calculation: under the section size of the continuous casting billet, the corresponding C value of the wide surface of the crystallizer is C1The narrow face of the crystallizer corresponds to the value C of 16.0422.75, in the production process, according to the combination formula of water temperature difference values of wide/narrow face inlet and outlet of crystallizer under the pulling speed
Regulating and controlling the water amount of the wide/narrow surface of the crystallizer in real time to ensure that the C value corresponding to the wide/narrow surface of the crystallizer in actual production and a simulation calculation result C1、C2The values are identical.
2) Controlling the specific water amount of the secondary cooling area of the continuous casting to be 0.65L/Kg, wherein the percentage of the water distribution amount of each cooling section of the secondary cooling area to the total water amount of the secondary cooling area is respectively as follows: the wide surface of the foot roller section accounts for 22%, the narrow surface of the foot roller section accounts for 5%, the upper part of the bending section accounts for 19%, the lower part of the bending section accounts for 15%, the segment 1 accounts for 13%, the segment 2 accounts for 9%, the segment 3-4 accounts for 10%, the segment 5 accounts for 4%, and the segment 7-9 accounts for 3%.
3) The arrangement mode of the nozzles of the secondary cooling fan-shaped section is 2-2-2 arrangement mode, the distance between the nozzles is regulated to be 300mm, and the continuous casting blank is not covered by spray water in the area of the fan-shaped section 100mm away from the edge of the casting blank.
The industrial test results show that the corner crack defects of the continuous casting billet are improved, but the effect is limited, and the number of corner cracks is still large.
Comparative example 3:
the method is adopted for peritectic steel continuous casting slabs with the thickness of 200mm multiplied by 1020mm, the steel grade is Q235B, the casting temperature is 1560 ℃, the drawing speed is 0.9m/min,
1) build boardThe mathematical model of the billet continuous casting solidification heat transfer is obtained through simulation calculation: under the section size of the continuous casting billet, the corresponding C value of the wide surface of the crystallizer is C1The narrow face of the crystallizer corresponds to the value C of 16.0422.75, in the production process, according to the combination formula of water temperature difference values of wide/narrow face inlet and outlet of crystallizer under the pulling speed
Regulating and controlling the water amount of the wide/narrow surface of the crystallizer in real time to ensure that the C value corresponding to the wide/narrow surface of the crystallizer in actual production and a simulation calculation result C1、C2The values are identical.
2) Controlling the specific water amount of the secondary cooling area of the continuous casting to be 0.55L/Kg, wherein the percentage of the water distribution amount of each cooling section of the secondary cooling area to the total water amount of the secondary cooling area is respectively as follows: the wide surface of the foot roll section accounts for 24%, the narrow surface of the foot roll section accounts for 5%, the upper part of the bending section accounts for 21%, the lower part of the bending section accounts for 16%, the section 1 of the sector accounts for 15%, the section 2 of the sector accounts for 9%, the section 3-4 of the sector accounts for 10%, and the section 5-9 of the sector is air-cooled.
3) The arrangement mode of the nozzles of the secondary cooling fan-shaped section is 2-2-2 arrangement mode, the original nozzle distance is kept unchanged at 400mm, and the secondary cooling area adopts a full-coverage spraying mode.
The industrial test result shows that the corner crack defect of the continuous casting billet is obviously improved, no other crack defects are generated on the wide surface of the casting billet, but cracks are generated inside part of the casting billet sample.
The continuous casting cooling technology for controlling cracks at corners of peritectic steel slabs provided by the embodiments of the present application is described in detail above. The above description of the embodiments is only for the purpose of helping to understand the method of the present application and its core ideas; meanwhile, for a person skilled in the art, according to the idea of the present application, there may be variations in the specific embodiments and the application scope, and in summary, the content of the present specification should not be construed as a limitation to the present application.
As used in the specification and claims, certain terms are used to refer to particular components. As one skilled in the art will appreciate, manufacturers may refer to a component by different names. This specification and claims do not intend to distinguish between components that differ in name but not function. In the following description and in the claims, the terms "include" and "comprise" are used in an open-ended fashion, and thus should be interpreted to mean "include, but not limited to. "substantially" means within an acceptable error range, and a person skilled in the art can solve the technical problem within a certain error range to substantially achieve the technical effect. The description which follows is a preferred embodiment of the present application, but is made for the purpose of illustrating the general principles of the application and not for the purpose of limiting the scope of the application. The protection scope of the present application shall be subject to the definitions of the appended claims.
It is also noted that the terms "comprises," "comprising," or any other variation thereof, are intended to cover a non-exclusive inclusion, such that a good or system that comprises a list of elements does not include only those elements but may include other elements not expressly listed or inherent to such good or system. Without further limitation, an element defined by the phrase "comprising an … …" does not exclude the presence of other like elements in a commodity or system that includes the element.
It should be understood that the term "and/or" as used herein is merely one type of association that describes an associated object, meaning that three relationships may exist, e.g., a and/or B may mean: a exists alone, A and B exist simultaneously, and B exists alone. In addition, the character "/" herein generally indicates that the former and latter related objects are in an "or" relationship.
The foregoing description shows and describes several preferred embodiments of the present application, but as aforementioned, it is to be understood that the application is not limited to the forms disclosed herein, but is not to be construed as excluding other embodiments and is capable of use in various other combinations, modifications, and environments and is capable of changes within the scope of the application as described herein, commensurate with the above teachings, or the skill or knowledge of the relevant art. And that modifications and variations may be effected by those skilled in the art without departing from the spirit and scope of the application, which is to be protected by the claims appended hereto.
Claims (9)
1. A continuous casting cooling method for controlling corner cracks of peritectic steel slabs is characterized by comprising the following steps:
1) controlling the energy speed ratio C of the crystallizer in the actual crystallization process to be unchanged;
the energy speed ratio C is specifically as follows:
in the formula, omega is a correction coefficient, W is the cooling water quantity of the wide/narrow face of the crystallizer, delta T is the water temperature difference of the inlet and outlet of the cooling water of the wide/narrow face of the crystallizer, and v is the pulling speed of the peritectic steel plate blank;
2) the cooling water amount of each cooling section of the secondary cooling zone is adjusted, so that the surface temperature of the continuous casting billet is uniformly distributed along the wide surface direction, and the temperature fluctuation along the billet drawing direction is reduced, thereby improving the longitudinal-transverse cooling uniformity of the continuous casting billet and reducing cracks;
the percentage of the cooling water amount of each cooling section of the second cooling area to the total cooling water amount of the second cooling area is as follows: the foot roller section accounts for 27% -29%, the bending section accounts for 35% -37%, the sector 1 section accounts for 14% -15%, the sector 2 section accounts for 8% -9%, and the sector 3-4 section accounts for 9% -10%; when the pulling speed is less than or equal to 1.1m/min, the fan-shaped sections 5-9 are not subjected to spray cooling; when the pulling speed is more than or equal to 1.1m/min, the sector 5-6 sections account for 2% -3%, and the rest cooling sections do not carry out spray cooling; when the pulling speed is more than or equal to 1.3m/min, the sector 7-9 sections account for 2-3 percent.
2. The continuous casting cooling method for controlling cracks at corners of peritectic steel slabs according to claim 1, wherein the content of the continuous casting cooling method further comprises: 3) and the foot roll section and the bending section of the secondary cooling area adopt a full-coverage spraying mode, and the nozzle distance of the fan-shaped section is adjusted, so that the continuous casting blank is not covered by spraying water in a region with the width of 100mm from the edge of the casting blank in the fan-shaped section.
3. The continuous casting cooling method for controlling cracks at the corners of peritectic steel slabs according to any one of claims 1 to 2, characterized in that the specific water amount of the secondary cooling zone is 0.53-0.68L/Kg, and the specific water amount is 0.25v +0.33, v being the drawing speed of the continuous casting machine.
4. The continuous casting cooling method for controlling corner cracks of peritectic steel slabs according to any one of claims 1 to 2, wherein the percentage of the cooling water amount of the foot roll section width and the narrow surface to the total cooling water amount of the secondary cooling zone is 22 to 24 percent and 4 to 5 percent respectively.
5. The continuous casting cooling method for controlling cracks at corners of peritectic steel slabs according to any one of claims 1 to 2, wherein the ratio of the amount of cooling water at the upper portion of the curved section is 20 to 21% and the ratio of the amount of cooling water at the lower portion of the curved section is 15 to 16%.
6. The continuous casting cooling method for controlling cracks at the corners of a peritectic steel slab as claimed in any one of claims 1 to 2, wherein the sectional size of the peritectic steel slab is (1020 x 200) mm to (1120 x 200) mm.
7. The continuous casting cooling method for controlling cracks at corners of peritectic steel slabs according to any one of claims 1 to 2, characterized in that water nozzles are adopted in the foot roller sections of the second cooling zone, and gas-mist nozzles are adopted in the rest cooling zones; the narrow sides of the casting blank are only provided with water nozzles at the foot roll sections, and the other cooling sections are air-cooled.
8. The continuous casting cooling method for controlling peritectic steel slab corner cracks according to claim 1, wherein the water distribution ratio of inner arcs and outer arcs of each cooling section of the second cooling zone is as follows: 1:1 of foot roller section, bending section: 1:1, segment 1: 1:1.2, sector 2 section 1:1.25, sector 3-4 sections: 1:1.35, 5-6 segments of a sector, 1:1.4, 7-9 segments of a sector: 1:1.5.
9. The continuous casting cooling method for controlling cracks at the corners of peritectic steel slabs according to claim 1, wherein the superheat degree of the peritectic steel during casting is 30-40 ℃.
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| CN113695548B (en) * | 2021-08-26 | 2023-01-31 | 宝武杰富意特殊钢有限公司 | Production process of continuous casting billet and continuous casting billet |
| CN113843402B (en) * | 2021-09-18 | 2023-05-19 | 山东钢铁股份有限公司 | Control method for internal solidification structure of gear steel oversized-section round billet |
| CN114653916B (en) * | 2022-02-28 | 2023-08-08 | 柳州钢铁股份有限公司 | Method for adjusting and controlling secondary cooling water quantity at edge of quality defect at corner of slab casting blank |
| CN114653913B (en) * | 2022-03-28 | 2023-10-17 | 山东钢铁集团日照有限公司 | Method for improving peritectic steel liquid level fluctuation of same-roller-diameter slab caster |
| CN116511441B (en) * | 2023-07-03 | 2023-10-13 | 北京科技大学 | Nozzle optimal arrangement method based on solidification characteristics of continuous casting billets |
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