LU501677B1 - Continuous casting cooling method for controlling corner cracks of peritectic steel slab - Google Patents

Abstract

The invention provides a continuous casting cooling method for controlling corner cracks of a peritectic steel slab, and relates to the technical field of steel continuous casting in ferrous metallurgy. Through the method, the corner cracks of the peritectic steel slab can be eliminated, other surface crack defects cannot be generated, and thus the quality of the peritectic steel continuous casting slab is effectively improved. The main contents of the method are as follows: 1) the energy-speed ratio C of a mould in the solidification process is controlled to be unchanged; 2) the ratio of the water quantity in each section of a secondary cooling zones to the total water quantity in the secondary cooling zones is as follows: a foot roller section: 27%-29%, a bending section: 35%-37%, a fan-shaped section I: 14%-15%, a fan-shaped section II: 8%-9%, and fan-shaped sections III-IV: 9%-10%; when the casting speed is less than or equal to 1.1 m/min, fan-shaped sections V-IX do not spray cooling water; when the casting speed is faster than or equal to 1.1 m/min, the spraying quantity of the fan-shaped sections V-VI is 2%-3%, and other sections do not spray cooling water; when the casting speed is faster than or equal to 1.3 m/min, the spraying quantity of the fan-shaped sections VII-IX is 2%-3%; and no spraying is performed in an area, 100 mm away from edge of the casting slab, of the fan-shaped sections. The technical scheme provided by the invention is suitable for the cooling process of steel continuous casting.

Description

CONTINUOUS CASTING COOLING METHOD FOR LUS01677

CONTROLLING CORNER CRACKS OF PERITECTIC STEEL SLAB TECHNICAL FIELD

[0001] The invention relates to the technical field of steel continuous casting in ferrous metallurgy, in particular to the continuous casting cooling method for controlling corner cracks of the peritectic steel slab.

BACKGROUND

[0002] The corner cracks of acontinuous casting slab mostly start from a mould and then extend in a secondary cooling zones and a straightening point, and finally form surface cracks. During the production of peritectic steel, peritectic reaction occurs in the mould, the linear shrinkage amount in a solidification process is large, heat flow distribution in the mould is not uniform, the thickness of a slab shell is not uniform, and slab cracks are generated. In addition, in the straightening process of the continuous casting slab, the temperature of the corner of the casting slab enters a brittleness temperature zone III, and under the dual action of grain boundary weakening and the vibration mark notch effect, the corner crack of the casting slab is further expanded and aggravated.

[0003] In order to solve the problem of cracks in casting peritectic steel, the cooling intensity of a mould is properly reduced in the existing technologies, and a weak cooling system is adopted in a secondary cooling zones to avoid expansion of the cracks, but this mode has the defects that the water quantity adjustment of the mould is not associated with the dynamic change of the water temperature difference of the cooling water inlet and outlet, and the actual application effect is greatly different from the simulation results; weak cooling is adopted in the secondary cooling zones, so the casting slab bulging phenomenon is caused, and the quality of a continuous casting slab is reduced; the water quantity adjustment of the secondary cooling zones is affected by the arrangement mode of nozzles of a continuous casting machine, and the 1 actual effect is limited. LU501677

[0004] The invention (Publication No.: CN 106735035 A) provides a method for reducing slab cracks by reducing the water flow of a nozzle at the corner of a casting slab and enabling the temperature of the corner of the casting slab to be higher than the brittleness temperature range of the casting slab. According to the method, the influence of casting slab mould cooling on the surface quality of the casting slab is not considered, and the reduction of the corner water spraying quantity of the continuous casting slab is limited in increase of the casting slab corner temperature or is insufficient to avoid the third brittleness temperature interval of the casting steel.

[0005] A control method for comer cracks of boron-containing steel slabs (Publication No.: CN 106825478 B) provides a quantitative relation between the water quantity of a mould and a secondary cooling zones and the product of the section size and the casting speed of a casting slab, so that the water distribution quantity of casting slab moulds and secondary cooling zones with different sizes is controlled, and then the corner cracks of the boron-containing steel slabs are controlled. The method does not consider the influence of the water temperature different change of the cooling water inlet/outlet of the mould on the cooling of themould, and the secondary cooling zones adopt a full-coverage spraying mode, so that the comer temperature of the casting slab is not favorably increased.

[0006] Therefore, it is necessary to study a continuous casting cooling method for controlling the corner cracks of the peritectic steel slab to overcome the defects in the existing technologies, so as to solve or relieve the one or more quality problems.

SUMMARY

[0007] For the above purpose, the invention provides the continuous casting cooling method for controlling the corner cracks of the peritectic steel slab, which can eliminate the corner cracks of the peritectic steel slab, cannot generate other surface crack defects, and effectively improve the quality of the peritectic steel continuous casting slab.

[0008] On the one hand, the invention provides the continuous casting cooling method for controlling corner cracks of the peritectic steel slab, which is characterized in that the 2 continuous casting cooling method comprises the following steps: LU501677

[0009] 1) the energy-to-speed ratio C in the solidification process of the mouldis controlled to be unchanged;

[0010] the energy-to-speed ratio Cis C = w * == wherein w is a correction coefficient, W is the cooling water quantity of the wide or narrow surface of themould, AT is the water temperature difference between the cooling water inlet and the cooling water outlet of the wide or narrow surface of the mould, and v is the casting speed of the peritectic steel slab, the C corresponding to wide surface of mould is C1, and the C corresponding to narrow surface of the mould is Cy;

[0011] the energy-to-speed ratio C in the actual solidification process remains consistent with the simulated C, and the simulated C is the energy-to-speed ratio when the thickness of the casting slab shell at the outlet of the mould reaches 15 mm;

[0012] 2) the percentage of the cooling water quantity of each cooling zoneof the secondary cooling zones in the total cooling water quantity of the secondary cooling zones is as follows: the foot roller section accounts for 27%-29%, the bending section accounts for 35%-37%, the fan-shaped section I accounts for 14%-15%, the fan-shaped section II accounts for 8%-9%, and the fan-shaped sections III-TV account for 9%-10%; when the casting speed is slower than or equal to 1.1 m/min, the fan-shaped sections V-IX do not spray cooling water; when the casting speed is faster than or equal to 1.1 m/min, the spraying quantity of the fan-shaped sections V- VI is 2%-3%, and other sections do not spray cooling water; when the casting speed is faster than or equal to 1.3 m/min, the spraying quantity of the fan-shaped sections VII-IX is 2%-3%.

[0013] According to the aspects and any possible implementation mode, the invention further provides the implementation, wherein the correction factor w = 1*107, and the unit is m/(L * DEG C); and the casting speed of the peritectic steel slab is 0.8-1.4 m/min.

[0014] According to the aspects and any possible implementation mode, an implementation mode is further provided, and the continuous casting cooling method further comprises the steps that 3) a full-coverage spraying mode is adopted for the foot roller section and the bending section of the secondary cooling zones, and the distance between nozzles of the fan-shaped section is adjusted, so that the continuous casting slab is not covered by spraying water in the 3 area, 100 mm away from the edge of the casting slab, of the fan-shaped section. LU501677

[0015] According to the aspects and any possible implementation mode, the invention further provides an implementation mode, wherein the specific water flowrate of the secondary cooling zones is 0.53 L/Kg to 0. 68 L/Kg, the calculation value of the cooling water quantity equation, which is 0.25v+0.33, is corresponding to the specific water flowrate, wherein v is the casting speed of a continuous casting machine.

[0016] According to the aspects and any possible implementation mode, an implementation mode is further provided, and the cooling water quantities of the wide surface and the narrow surface of the foot roller section account for 22%-24% and 4%-5% of the total cooling water quantity of the secondary cooling zones respectively.

[0017] According to the aspects and any possible implementation mode, an implementation mode 1s further provided, the cooling water quantity of the upper portion of the bending section accounts for 20%-21%, and the cooling water quantity of the lower portion of the bending section accounts for 15%-16%.

[0018] According to the aspects and any possible implementation mode, an implementation mode is further provided, and the size of the section of the peritectic steel slab is(1,020-1,120) mm * 200 mm.

[0019] According to the aspects and any possible implementation mode, an implementation mode is further provided, a water nozzle is adopted in the foot roller section of the secondary cooling zones, and air-mist nozzles are adopted in other cooling zones of secondary cooling zones; water nozzles are only arranged on the foot roller section of the narrow edge of the casting slab, and other cooling zones of the narrow edge are air-cooled.

[0020] According to the aspects and any possible implementation mode, an implementation mode is further provided, and the water distribution ratio of an inner arc to an outer arc of each cooling zone of the secondary cooling zones are as follows: the foot roller section: 1: 1, the bending section: 1: 1, the fan-shaped section I: 1: 1.2, the fan-shaped section II: 1: 1.25, the fan- shaped sections III-IV: 1: 1.35, the fan-shaped sections V-VI: 1: 1.4, and the fan-shaped sections VII-IX: 1: 1.5.

[0021] According to the above aspects and any possible implementation mode, an implementation mode is further provided, and the superheat degree during peritectic steel 4 casting is 30-40 DEG C. LU501677

[0022] Compared with the existing technologies, the invention has the following technical effects that 1) the cooling water quantity of the mouldis controlled in real time through the water temperature difference of the cooling water inlet/outlet of the mouldand the casting speed, and the cooling intensity of the mould is maintained in a stable weak cooling state in the peritectic steel continuous casting slab process, so that the thickness uniformity of an initial blank shell is improved, and the probability of forming primary cracks in the mould is reduced; 2) in the process of designing the water quantity of the secondary cooling zones, in combination with the adjustment of a nozzle arrangement mode, the problem of casting slab bulging caused by weak cooling of a conventional secondary cooling zones is avoided while it is ensured that the corner temperature of the casting slab in the straightening zone is higher than the upper limit of a third brittleness temperature area of the casting steel grade, the surface temperature of the casting slab is evenly distributed in the wide surface direction, the temperature fluctuation in the casting direction is smaller, the longitudinal-transverse cooling uniformity of the continuous casting slab is improved, the quality of the casting slab is obviously improved, and the production efficiency is improved.

[0023] Certainly, when any product of the embodiments of the invention is implemented, all the technical effects are not necessarily required to be achieved at the same time.

BRIEF DESCRIPTION OF DRAWINGS

[0024] To more clearly illustrate the technical solution of the embodiment of the invention, the drawing required in the embodiment is simply introduced; obviously, the drawings described below are only some embodiments of the invention, and for common technicians in the field, other drawings can be obtained according to the drawings on the premise that creative labor is not paid.

[0025] Fig. 1 is a schematic diagram for segmenting the secondary cooling zones of the continuous casting machine provided by one embodiment of the invention.

[0026] wherein in the Fig. 1:

[0027] 1 represents the foot roller section, 2 represents the upper part of the bending section, 5

3 represents the lower part of the bending section, and 4 to 12 represent the fan-shaped sections LU501677 I-TX respectively.

DESCRIPTION OF EMBODIMENTS

[0028] In order to better understand the technical scheme of the invention, the embodiment ofthe invention is described in detail in combination with the attached drawing.

[0029] It should be explicit that the described embodiment is only a part of the embodiments of the invention, rather than all of the embodiments of the invention. Based on the embodiment of the invention, all other embodiments obtained by common technicians in the field on the premise of not making creative labor belong to the range of protection of the invention.

[0030] The terms used in embodiments of the invention are only intended to describe a particular embodiment, but not intended to be limiting the invention. The ‘one’ in the singular form used in the embodiment of the invention and in the attached claims, ‘said’ and ‘this’ are also intended to include a majority of forms unless the context clearly represents other meanings.

[0031] On the basis of numerical simulation research on solidification heat transfer of the continuous casting slab, the mould cooling, continuous casting machine secondary cooling and secondary cooling fan-shaped section nozzle spacing parameters are designed and optimized, the longitudinal -transverse cooling uniformity of the continuous casting slab is improved, and the method aims at eliminating corner cracks of the peritectic steel continuous casting slab without generating other surface defects and improving the production efficiency of the peritectic steel continuous casting slab. Therefore, the quality of the peritectic steel continuous casting slab is improved.

[0032] The invention provides a continuous casting cooling technology for controlling corner cracks of the peritectic steel slab:

[0033] (1) establishing a solidification and heat transfer mathematical model for slab continuous casting , and through simulation calculation, respectively obtaining the water consumption of the wide or narrow surface of the continuous casting slab at a mould outlet with the casting slab shell thickness of 15mm, wherein the calculation formula of the ratio C of the product of the cooling water quantity of the mould wide or narrow surface and the cooling water 6 inlet/outlet water temperature difference to the casting speed (energy-speed ratio in the LU501677 invention) is:

[0034] C= w + MAT. Vo

[0035] wherein w is a correction coefficient, the unit is m/(L * DEG C), and w =1* 10" 3, Wo is the water quantity of the wide or narrow surface of the mould, L/min; AT, is the initial water temperature difference (DEG C) of the cooling water inlet/outlet of the wide or narrow surface of themould, and vo is the initial casting speed (m/min) of the continuous casting machine.

[0036] the water quantity of the wide or narrow surface of the continuous casting slab and the mould refers to the total cooling water quantity of the wide surface or the narrow surface.

[0037] Cs of wide or narrow surfaces of moulds under different continuous casting slab section sizes are determined through simulation calculation, and during the actual production, in combination with the formula C = w * == according to caster pouring speed in casting process and corresponding inlet and outlet water temperature difference values of wide or narrow surfaces of moulds, the water quantity of the wide or narrow surface of the mould is regulated and controlled in real time, so that a C in actual production is consistent with simulation calculation results and is kept unchanged in the cooling process, wherein w is a correction coefficient (m/(L * DEG C)), w= 1 * 10%, W is the water quantity of the wide or narrow surface of the mould (L/min), AT is the water temperature difference (DEG C) of the cooling water inlet/outlet of the wide or narrow surface of themould, and v is the casting speed (m/min) of the continuous casting machine.

[0038] (2) the percentage of the water distribution quantity of each cooling zone of the secondary cooling zones in the total water quantity of the secondary cooling zones are as follows: the foot roller section accounts for 27%-29%, the bending section accounts for 35%- 37%, the fan-shaped section I accounts for 14%-15%, the fan-shaped section II accounts for 8%-9%, the fan-shaped sections III-IV account for 9%-10%; when the casting speed is less than or equal to 1.1 m/min, the fan-shaped sections V-IV do not perform spray cooling; when the casting speed is faster than or equal to 1.1 m/min, the fan-shaped sections V-VI account for 2%- 3%, other cooling sections do not perform spray cooling; and when the casting speed is faster 7 than or equal to 1.3 m/min, the fan-shaped sections VII-IX account for 2%-3%. LU501677

[0039] (3) a full-coverage spraying mode is adopted for the foot roller section and the bending section of the secondary cooling zones, and the distance between nozzles of the fan- shaped section is adjusted, so that the continuous casting slab is not covered by spraying water in the zone, 100 mm away from the edge of the casting slab, of the fan-shaped section.

[0040] The specific water flowrate of the secondary cooling zones is 0.53-0.68 L/Kg, the specific water flowrate and the casting speed of the continuous casting slab are in a linear relation, and the calculation formula is shown as follows:

[0041] w=0 .25Av+0 33,

[0042] wherein w is the specific water flowrate (L/Kg); À is a correction coefficient, L * min/(Kg.m), and À = 1; v is the casting speed of the continuous casting machine (m/min).

[0043] The water quantity of the wide surface and the water quantity of the narrow surface of the foot roller section account for 22%-24% and 4%-5% of the total water quantity of the secondary cooling zones respectively.

[0044] The water quantity of the upper part of the bending section accounts for 20%-21%, and the water quantity of the lower part of the bending section accounts for 15%-16%. The foot roller section of the secondary cooling zones adopts a water nozzle, and the other cooling sections adopt air-mist nozzles; water nozzles are only arranged on the foot roller section of the narrow edge of the casting slab, and other cooling sections of the narrow edge are air-cooled.

[0045] The water distribution ratio of the inner arc to the outer arc of each cooling section in the secondary cooling zones are as follows: the foot roller section: 1: 1, the bending section: 1: 1, the fan-shaped section I: 1: 1.2, the fan-shaped section IT: 1: 1.25, the fan-shaped sections I-IV: 1: 1.35, the fan-shaped sections V-VI: 1: 1.4, and the fan-shaped sections VII-IX: 1: 1.5.

[0046] The casting speed of the peritectic steel continuous casting slab is 0.8-1.4 m/min.

And the section size of the peritectic steel slab is (1,020-1,120) mm * 200 mm. The superheat degree of the peritectic steel during casting is 30-40 DEG C.

[0047] Two quality problems in the continuous casting production process can be effectively solved by controlling the cooling water quantity of the wide or narrow surface of the mould and the ratio of the product of the water temperature difference of the cooling water inlet and the cooling water outlet to the casting speed to be unchanged: 8

[0048] 1) during the casting of peritectic steel, the water distribution quantity of a mouldis LU501677 not matched with the casting speed of a continuous casting slab, the cooling intensity of the mould is larger or smaller, the water distribution quantity of the mould can increase solidification shrinkage of an initial blank shell of the continuous casting slab in a meniscus area of themould, uneven cooling of the continuous casting slab in the mould is aggravated, and therefore even growth of the solidified blank shell is not facilitated; the occurrence probability of surface cracks is increased; the latter can cause that the shell thickness of the continuous casting slab at the outlet of the mould cannot meet the safe shell thickness requirement (>=15mm), and the bleed-out risk is increased;

[0049] 2) in the casting process, the water temperature difference of a cooling water inlet/outlet of the mould under different time and working conditions fluctuates, and the water distribution quantity of the mould is not correspondingly adjusted, so that the cooling intensity of the mould is changed, the quality of an initial blank shell of a continuous casting slab is influenced, and the quality of the continuous casting slab cannot be stable and effectively controlled.

[0050] According to the invention, the percentage of water quantity in each section of the secondary cooling zones 1s optimized, the percentage of the water quantity of the wide surface of the foot roller section 1s controlled to be 27%-29%, the strength of the continuous casting slab 1s increased, and the situation that the continuous casting slab generates larger temperature return after being discharged from themould, and thus surface cracks are induced is avoided. The percentage of the water quantity of the upper portion of the bending section is controlled to be 20%-21%, the percentage of the water quantity of the lower portion of the bending section is controlled to be 15%-16%, the longitudinal cooling uniformity of the continuous casting slab can be improved, the surface temperature of the casting slab is further reduced, and the casting slab is prevented from bulging. And the percentage of the water quantity of the fan-shaped section I is controlled to be 14%-15%, the percentage of the water quantity of the fan-shaped section II is controlled to be 8%-9%, and the percentage of thewater quantity of the fan-shaped sections III-IV is controlled to be 9%-10%, so that the longitudinal cooling uniformity of the continuous casting slab is ensured while weak cooling is adopted, and the corner temperature of the continuous casting slab can be increased. The percentage of the water quantity of the 9 narrow surface of the foot roller section is controlled to be 4%-5%, and air cooling is conducted LU501677 on the narrow surface of the continuous casting slab in other cooling sections; air cooling is conducted on the continuous casting slab in a straightening zone (six fan-shaped sections) when the casting speed is less than or equal to 1.1 m/min, a small quantity of water is distributed when the casting speed is faster than or equal to 1.1 m/min, so the corner temperature of the continuous casting slab can be further increased, it is guaranteed that the continuous casting slab have good plasticity in the straightening zone, and the corner cracks are avoided.

[0051] An existing technical method adopting a weak cooling system in a secondary cooling zones can inevitably increase the occurrence probability of bulging of a continuous casting slab. By means of the method for adjusting the distance between the nozzles of the secondary cooling fan-shaped section, the area, 100 mm away from the edge of the casting slab, of the fan-shaped section of the continuous casting slab is not covered with spraying water, the corner temperature of the continuous casting slab is further increased, and the comer crack defect can be eliminated easily. Meanwhile, according to the method, the spraying overlapping area between the adjacent nozzles is increased, the cooling intensity of the center area of the wide surface of the continuous casting slab is improved, the temperature of the center area is kept below 1,100 DEG C, and the bulging phenomenon of the casting slab can be effectively prevented.

[0052] In each embodiment of the invention, the subareas and subsections of the secondary cooling zones are shown in table 1. cooling zones to the meniscus of the mould

IT

HI 10

IV V VI VII VII IX

[0053]

[0054] Table 1

[0055] Embodiment 1:

[0056] The method provided by the invention is adopted for a 200 mm * 1,020 mm peritectic steel continuous casting slab, the steel grade is Q235B, the pouring temperature is 1,560 DEG C, and the casting speed is 0. 9 m/min.

[0057] 1) establishing a solidification and heat transfer mathematical model fora slab continuous casting , and obtaining the results: the C corresponding to wide surface of the mould is C1 = 16.04, and the C corresponding to narrow surface of mould is Ca = 2.75, regulating and controlling the water quantity of the wide or narrow surface of the mouldin real time by combining the temperature difference value of inlet and outlet water of the wide or narrow 11 surface of the mould under the casting speed and the formula C = w * ==. so the C LU501677 corresponding to the wide or narrow surface of the mould in actual production is consistent with the C1 and C of the simulation results;

[0058] 2) controlling the specific water flowrate of the continuous casting secondary cooling zones to be 0. 56 L/Kg, wherein the percentage of the water distribution quantity of each cooling section of the secondary cooling zones in the total water quantity of the secondary cooling zones is as follows: the wide surface of the foot roller section accounts for 24%, 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 16%, the fan-shaped section I accounts for 15%, the fan-shaped section II accounts for 9%, the fan-shaped sections III-IV account for 10%, and the fan-shaped sections V-IX are air-cooled;

[0059] 3) arranging the nozzles of the secondary cooling fan-shaped section in a 2-2-2 mode, and regulating and controlling the distance between the nozzles to be 300 mm, so that the continuous casting slab is not covered by the spraying water in the zone, which is 100 mm away from the edge part of the casting slab, of the fan-shaped section.

[0060] Industrial trial results show that the corner crack defect of the continuous casting slab disappears, no other crack defect is generated on the surface of the casting slab, and the quality of the continuous casting slab is higher.

[0061] Embodiment 2:

[0062] when the method is adopted for the 200 mm * 1,020 mm peritectic steel continuous casting slab, the steel grade is Q235B, the casting temperature is 1,560 DEG C, and the casting speed is 1.1 m/min;

[0063] 1) establishing a solidification and heat transfer mathematical model for slab continuous casting, and obtaining the following results through simulation calculation: under the section size of the continuous casting slab, the C corresponding to the wide surface of the mould is C1 = 16.04, the C corresponding to the narrow surface of the mould is Ca = 2.75, and in the production process, the water quantity of the wide or narrow surface of the mould is regulated in real time according to the water inlet and outlet temperature difference value of the wide or narrow surface of the mould at the casting speed in combination with the formula C = 12 œ * == the C corresponding to the wide or narrow surface of the mould in actual production LU501677 is consistent with the C1 and C> of the simulation results;

[0064] 2) controlling the specific water flowrate of the continuous casting secondary cooling zones to be 0.61 L/Kg, and the percentage of the water distribution quantity of each cooling section of the secondary cooling zones in the total water quantity of the secondary cooling zones is 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 21%, the lower part of the bending section accounts for 15%, the fan-shaped section I accounts for 15%, the fan-shaped section II accounts for 9%, the fan-shaped sections I-IV account for 10%, and the fan-shaped sections V-IX are air-cooled;

[0065] 3) arranging the nozzles of the secondary cooling fan-shaped section in the 2-2-2 arrangement mode, and regulating and controlling the distance between the nozzles to be 300 mm, so that the continuous casting slab is not covered by the spraying water in the area, which is 100 mm away from the edge part of the casting billet, of the fan-shaped section.

[0066] Industrial trial results show that the corner crack defect of the continuous casting slab disappears, no other crack defect is generated on the surface of the casting slab, and the quality of the continuous casting slab is higher.

[0067] Embodiments 3:

[0068] when the method is adopted for a 200 mm * 1,020 mm peritectic steel continuous casting slab, the steel grade is Q235B, the casting temperature is 1,560 DEG C, and the casting speed is 1. 4 m/min;

[0069] 1) establishing the solidification and heat transfer mathematical model for the slab continuous casting mathematical model of solidification heat transfer, and obtaining the following results through simulation calculation: under the section size of the continuous casting slab, the C corresponding to the wide surface of the mould is Ci = 16.04, the C corresponding to the narrow surface of the mould is C> = 2.75, and in the production process, the water quantity of the wide or narrow surface of the mould is regulated in real time according to the water inlet and outlet temperature difference value of the wide or narrow surface of the mould at the casting speed in combination with the formula C = w * > ; the C 13 corresponding to the wide or narrow surface of the mould in actual production is consistent LU501677 with the C1 and C of the simulation results;

[0070] 2) controlling the specific water flowrate of the continuous casting secondary cooling zones to be 0.68 L/Kg, wherein the percentage of the water distribution quantity of each cooling zone of the secondary cooling zones in the total water quantity of the secondary cooling zones 1s 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 fan-shaped section I accounts for 14%, the fan-shaped section II accounts for 9%, the fan-shaped sections III-TV account for 9%, the fan-shaped sections V-VI account for 3% and the fan-shaped sections V-IX account for 2%;

[0071] 3) arranging the nozzles of the secondary cooling fan-shaped section in the 2-2-2 arrangement mode, and regulating and controlling the distance between the nozzles to be 300 mm, so that the continuous casting slab is not covered by the spraying water in the area, which is 100 mm away from the edge part of the casting billet, of the fan-shaped section.

[0072] Industrial trial results show that the corner crack defect of the continuous casting slab disappears, no other crack defect is generated on the surface of the casting slab, and the quality of the continuous casting slab is higher.

[0073] Contrast embodiment 1:

[0074] when the method is adopted for the 200 mm * 1,020 mm peritectic steel continuous casting slab, the steel grade is Q235B, the casting temperature is 1,560 DEG C, and the casting speed is 0.9 m/min/,

[0075] 1) controlling the wide-surface water distribution quantity of the mould to be 2,685 L/min and the narrow-surface water distribution quantity to be 465 L/min, and keeping the wide or narrow-surface water distribution quantity of the mould unchanged in the continuous casting process;

[0076] 2) controlling the specific water flowrate of the continuous casting secondary cooling zones to be 0.55 L/Kg, wherein the percentage of the water distribution quantity of each cooling section of the secondary cooling zones in the total water quantity of the secondary cooling zones is as follows: the wide surface of the foot roller section accounts for 24%, the 14 narrow surface of the foot roll section accounts for 5%, the upper part of the bending section LU501677 accounts for 21%, the lower part of the bending section accounts for 16%, the fan-shaped section I accounts for 15%, the fan-shaped section II accounts for 9%, the fan-shaped sections I-IV accounts for 10%, and the fan-shaped sections V-IX are air-cooled;

[0077] 3) arranging the nozzles of the secondary cooling fan-shaped section in the 2-2-2 mode, and regulating and controlling the distance between the nozzles to be 300mm, so that the continuous casting slab is not covered by the spraying water in the area, which is 100mm away from the edge part of the casting billet, of the fan-shaped section.

[0078] Industrial trial results show that the corner crack defect of the continuous casting slab is obviously improved, but a large number of fine longitudinal cracks are distributed on the wide surface of the casting slab, and the quality of the continuous casting slab is lower.

[0079] Contrast embodiment 2:

[0080] when the method is adopted for a 200 mm * 1,020 mm peritectic steel continuous casting slab, the steel grade is Q235B, the casting temperature is 1,560 DEG C, and the casting speed is 0.9 m/min;

[0081] 1) establishinga solidification heat transfer mathematical model for slab continuous casting, and obtaining the following results through simulation calculation: under the section size of the continuous casting slab, the C corresponding to the wide surface of the mould is C1 = 16.04, the C corresponding to the narrow surface of the mould is Ca = 2.75, and in the production process, the water quantity of the wide or narrow surface of the mould is regulated in real time according to the water inlet and outlet temperature difference value of the wide or narrow surface of the mould at the casting speed in combination with the formula C = w * == the C corresponding to the wide or narrow surface of the mould in actual production is consistent with the C1 and C3 of the simulation results;

[0082] 2) controlling the specific water flowrate of the continuous casting secondary cooling zones to be 0.65 L/Kg, wherein the percentage of the water distribution quantity of each cooling section of the secondary cooling zones in the total water quantity of the secondary cooling zones is 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 15 accounts for 19%, the lower part of the bending section accounts for 15%, the fan-shaped LU501677 section I accounts for 13%, the fan-shaped section II accounts for 9%, the fan-shaped sections I-IV account for 10%, the fan-shaped section V accounts for 4%, and the fan-shaped sections VII-IX account for 3%;

[0083] 3) arranging the nozzles of the secondary cooling fan-shaped section in the 2-2-2 arrangement mode, and regulating and controlling the distance between the nozzles to be 300 mm, so that the continuous casting slab is not covered by the spraying water in the area, which is 100 mm away from the edge part of the casting billet, of the fan-shaped section.

[0084] Industrial trial results show that the corner crack defect of the continuous casting slab is improved, but the effect is limited, and the number of corner cracks is still larger.

[0085] Contrast embodiment 3:

[0086] when the method is adopted for a 200 mm * 1,020 mm peritectic steel continuous casting slab, the steel grade is Q235B, the casting temperature is 1,560 DEG C, and the casting speed is 0.9 m/min;

[0087] 1) establishing a solidification and heat transfer mathematical model for a slab continuous casting mathematical model of solidification heat transfer, and obtaining the following results through simulation calculation: under the section size of the continuous casting slab, the C corresponding to the wide surface of the mould is C1 = 16.04, the C corresponding to the narrow surface of the mould is C> = 2.75, and in the production process, the water quantity of the wide or narrow surface of the mould is regulated and controlled in real time according to the temperature difference value of the water inlet and outlet of the wide or narrow surface of the mould at the casting speed in combination with the formula C = w + == the C corresponding to the wide or narrow surface of the mould in actual production is consistent with the C1 and C: of the simulation results;

[0088] 2) controlling the specific water flowrate of the continuous casting secondary cooling zones to be 0.55 L/Kg, wherein the percentage of the water distribution quantity of each cooling zone of the secondary cooling zones in the total water quantity of the secondary cooling zones 1s as follows: the wide surface of the foot roller section accounts for 24%, the narrow surface of the foot roller section accounts for 5%, the upper part of the bending section accounts 16 for 21%, the lower part of the bending section accounts for 16%, the fan-shaped section I LU501677 accounts for 15%, the fan-shaped section II accounts for 9%, the fan-shaped section III-TV sections account for 10%, and the fan-shaped sections V-IX are air-cooled;

[0089] 3) arranging the nozzles of the secondary cooling fan-shaped section in the 2-2-2 mode, keeping the original nozzle distance of 400 mm unchanged, and adopting a full-coverage spraying mode in the secondary cooling zones.

[0090] Industrial trial results show that the corner crack defect of the continuous casting slab is obviously improved, no other crack defect is generated on the wide surface of the casting slab, but cracks are generated in part of casting slab samples.

[0091] The continuous casting cooling technology for controlling the comer cracks of the peritectic steel slab, provided by the embodiment of the invention, is introduced in detail above. The description of the embodiment is only used for helping to understand the method and the core thought of the method; meanwhile, for general technicians in the field, according to the thought of the invention, the specific implementation mode and the application range are changed, and in conclusion, the content of the specification should not be understood as limitation to the invention.

[0092] Certain vocabularies are used as in the description and claims to refer to particular components. Technicians in the field should understand that hardware manufacturers may use different nouns to name the same component. The specification and the claims do not take the difference of names as a mode for distinguishing the components, but take the difference of the components in function as a criterion for distinguishing. As mentioned in the whole description and claims, ‘contain’ and ‘include’ are each an open term, so it should be explained as ‘contain/include but not limited’. The ‘general’ means that in a receivable error range, technicians in the field can solve the technical problem in a certain error range, and the technical effect is basically achieved. The description is subsequently described as a better implementation mode for implementing the invention, and the description aims at explaining the general principle of the invention and is not used for limiting the range of the invention. The protection range of the invention is based on the definition of the attached claims.

[0093] It also needs to be illustrated that the terms ‘contain’, ‘include’, or any other variant thereof are intended to encompass non-exclusive inclusion, such that a commodity or system 17 comprising a series of elements not only comprises those elements, but also comprises other LU501677 elements that are not explicitly listed, or also comprises an element inherent to such a commodity or system. Elements defined by statements ‘include one...” without more restrictions, without excluding the presence of additional identical elements in goods or systems including the elements.

[0094] It should be understood that the term ‘and/or’ used herein is only an association relation describing an associated object, which indicates that three relations may exist; for example, A and/or B may indicate that A is present alone, A and B are present at the same time, and B is present alone. In addition, the character ‘/’ in the text generally represents that the front and back associated objects are one ‘or’ relation.

[0095] Several preferred embodiments of the invention are shown and described above, but as previously described, it should be understood that the invention is not limited to the forms disclosed herein, not to be regarded as exclusions of other embodiments, but can be used in various other combinations, modifications, and environments, and can be used in various other combinations, modifications, and environments within the scope of the idea of the invention described herein. The modification is made through the teaching or the technology or knowledge of the related field. However, the modification and change performed by the personnel in the field are not separated from the spirit and range of the invention, and should be within the protection scope of the claims attached to the invention.

18

Claims (10)

CLAIMS What is claimed is:

1. A continuous casting cooling method for controlling the corner cracks of aperitectic steel slab is characterized in that the continuous casting cooling method comprises the following steps: 1) controlling an energy-speed ratio C of a mould in an actual solidification process to be unchanged, wherein the energy-speed ratio C is C = w * ==, w is a correction coefficient, W is the cooling water quantity of the wide or narrow surface of the mould, AT is the water temperature difference between a cooling water inlet and a cooling water outlet of the wide or narrow surface of the mould, and v is the casting speed of the peritectic steel slab; 2) adjusting the cooling water quantity of each cooling zone of the secondary cooling zones, so that the surface temperature of the continuous casting slab is uniformly distributed in the wide surface direction, the temperature fluctuation in the slab drawing direction is reduced, the longitudinal-transverse cooling uniformity of the continuous casting slab is improved, and cracks are reduced.

2. Method according to the claim 1, the continuous casting cooling method for controlling the corner cracks of the peritectic steel slab is characterized in that the percentage of the cooling water quantity of each cooling section of the secondary cooling zones in the total cooling water quantity of the secondary cooling zones is as follows: a foot roller section accounts for 27%-29%, a bending section accounts for 35%-37%, a fan-shaped section I accounts for 14%-15%, a fan-shaped section II accounts for 8%-9%, and fan-shaped section ITI-IV account for 9%-10%; when the casting speed is slower than or equal to 1.1 m/min, fan-shaped sections V-IX do not spray cooling water; when the casting speed is faster than or equal to 1.1 m/min, the spraying quantity of the fan-shaped sections V-VI is 2%-3%, and other sections do -19-

not spray cooling water; when the casting speed is faster than or equal to 1.3 m/min, LU501677 the spraying quantity of the fan-shaped sections VII-IX is 2%-3%.

3. Method according to the claim 1, the continuous casting cooling method for controlling the corner cracks of the peritectic steel slab is characterized by further comprising the steps that 3) a full-coverage spraying mode is adopted for the foot roller section and the bending section of the secondary cooling zones, and the distance between nozzles of the fan-shaped section is adjusted, so the continuous casting slab is not covered by spraying water in the area, 100 mm away from the edge of the casting slab, of the fan-shaped section.

4. Method according to any one of claims 1-3, the continuous casting cooling method forcontrolling the corner cracks of the peritectic steel slab is characterized in that the specific water flowrate of the secondary cooling zones is 0.53-0.68 L/Kg, and the value of specific water flowrate is equal to the value of 0.25v + 0.33, wherein v is the casting speed of a continuous casting machine.

5. Method according to any one of claims 1-3, the continuous casting cooling method for controlling the corner cracks of the peritectic steel slab is characterized in that the cooling water quantity of the wide surface of the foot roller section accounts for 22%- 24% of the total cooling water quantity of the secondary cooling zones, and the cooling water quantity of the narrow surface of the foot roller section accounts for 4%-5% of the total cooling water quantity of the secondary cooling zones.

6. Method according to any one of claims 1-3, the continuous casting cooling method for controlling the corner cracks of the peritectic steel slab is characterized in that the cooling water quantity of the upper part of the bending section accounts for 20-21%, and the cooling water quantity of the lower part of the bending section accounts for 15-16%.

7. Method according to any one of claims 1-3, the continuous casting cooling method for controlling the corner cracks of the peritectic steel slab is characterized in that the section size of the peritectic steel slab is (1,020-1,120) mm * 200 mm.

8. Method according to any one of claims 1-3, the continuous casting cooling method -20 -

for controlling the corner cracks of the peritectic steel slab is characterized in that a water LU501677 nozzle is adopted in the foot roller section of the secondary cooling zones, and air-mist nozzles are adopted in other cooling sections; water nozzles are only arranged on the foot roller section of the narrow edge of the casting slab, and other cooling sections of the narrow edge are air-cooled.

9. Method according to the claim 1, the continuous casting cooling method for controlling the corner cracks of the peritectic steel slab is characterized in that the water distribution ratio of an inner arc to an outer arc of each cooling section of the secondary cooling zones is as follows: the foot roller section: 1: 1, the bending section: 1: 1, the fan-shaped section I: 1: 1.2, the fan-shaped section IT: 1: 1.25, the fan-shaped sections I-IV: 1: 1.35, the fan-shaped sections V-VI: 1: 1.4, and the fan-shaped sections VII-IX:

1. 1.5.

10. Method according to the claim 1, the continuous casting cooling method for controlling the corner cracks of the peritectic steel slab is characterized in that the degree of superheat is 30-40 DEG C when peritectic steel is cast.

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