JP3401785B2 - Cooling method of slab in continuous casting - Google Patents

Description

Detailed Description of the Invention

[0001]

TECHNICAL FIELD The present invention relates to continuous casting of blooms or billets (hereinafter referred to as cast pieces) of various steels such as carbon steel, low alloy steel, high and low alloy steel, and stainless steel,
The present invention relates to a method for cooling a slab capable of reducing center porosity or center segregation generated at the center of the slab.

[0002]

2. Description of the Related Art A seamless steel pipe is manufactured by a Mannesmann method or a Eugene Sejournet method by a rolling or forging process. However, when center porosity or center segregation is present in a continuously cast slab, the internal part of the slab is present. Is the inner surface of the pipe, and if the degree is large, the manufactured inner surface of the pipe is flawed, which is likely to be a quality defect.

[0003] As a method of reducing center porosity and center segregation of a continuously cast slab, some secondary cooling methods that utilize heat shrinkage during slab cooling have already been proposed. For example, 2 to 1 in front of the most distal position in the casting direction of the residual molten metal pool
Along the casting direction from the 5m position to the pool tip position,
As the liquid core nucleus of the slab progresses to solidify, the slab surface is forcibly cooled by an amount equivalent to or more than the volume shrinkage due to the solidification shrinkage to shrink the solidified shell of the slab, and the cross section of the slab is reduced for casting. However, a method for reducing center segregation (Japanese Patent Laid-Open No. 62-61764) has been proposed.

[0004] Further, the slab surface temperature along the casting direction from a position 2 to 15 m before the most distal position in the casting direction of the residual molten metal pool to the tip of the pool is adjusted according to the progress of solidification of the liquid core of the slab. A ₃ transformation temperature of steel or A _{C 3} transformation start temperature T _A
As described above, the method for reducing the center segregation by forcibly cooling to a temperature below the effective cast surface temperature T _V shown in the following formula to shrink the solidified shell of the cast, reduce the cross section of the cast, and cast to reduce the center segregation Fairness 3-46217
Issue). T _V = Ta + (T _N −Ta) × 0.3 where T _{N is the} surface temperature of the slab by natural cooling after leaving the pinch roll, and Ta is the average cooling of the solidified shell required to compensate for the amount of solidification shrinkage. Slab surface temperature

[0005] The casting position of the residual molten metal pool is in front of the most distal position
From the position of 2 to 15 m to the pool tip position, the volume contraction amount equivalent to or more than the volumetric shrinkage due to solidification shrinkage accompanying the solidification progress of the residual molten steel of the slab along the casting direction is supplemented by the shrinkage load of the solidified shell due to successive cooling of the slab surface In the continuous casting method, a slab solidification heating device is installed in front of the position where the sequential cooling is performed, and the average temperature of the solidified slab of the slab is increased, and then the slab is cast by reducing the cross section of the slab by sequentially cooling. A method for reducing center segregation (Japanese Patent Laid-Open No. 63-30161) has been proposed.

[0006] In front of the most distal position of the residual molten metal pool in the casting direction
The slab surface from the position of 2 to 15 m to the pool tip position, along the casting direction, as the solidification of the liquid core of the slab progresses,
Detects the leading edge of the residual molten metal pool in the casting direction when the casting solidified shell is shrunk by successive forced cooling with a cooling amount equal to or more than the volumetric shrinkage amount due to the solidification shrinkage to reduce the cross section of the slab and casting. Then, based on the detection, the solidification shrinkage amount of the slab and the surface temperature at which the surface shrinkage should be compensated are calculated, casting is performed by adjusting the water cooling zone length, the cooling water amount and the cooling pattern so as to reach the temperature. A method of reducing segregation (Japanese Patent Laid-Open No. 63-165053) has been proposed.

[0007] For a circular slab drawn from a continuous casting mold, forced cooling is performed over a region of at least 5 m until the solidification completion point of the slab, and the surface temperature of the slab is continuously lowered. There has been proposed a method (Japanese Patent Laid-Open No. 1-118351) in which casting is performed while preventing reheat and a suitable circle or a cross-sectional shape close thereto is obtained.

[0008] When the core of the continuously cast slab is in the state of the soft solidification phase, the difference in heat balance between the soft core and the already solidified shell around the core causes the core to be separated by the shell. Forced cooling of the slab so that it will always be compressed
For example, the average flow rate per hour and 1 m ^{3 of} slab is 8
A method (Japanese Patent Application Laid-Open No. 2-15856) for carrying out the treatment at -15 m ³ has been proposed.

[0009] When the solid fraction at the center of the slab becomes 0.1 to 0.3, the surface cooling of the slab is started by water cooling with a water amount density of 25 to 100 [liter / (min. · M ² )]. The solid fraction at the center of one side is 0.
A method to reduce the center porosity by continuing the water cooling with the above water density until it becomes 8 or more (Patent No. 2856068).
No.) is proposed.

[0010] When the solid fraction of the slab center during casting becomes 0.1 to 0.3, water cooling is started on the short side surface side of the slab, and the solid fraction of the slab center is 0.8 or more. A method has been proposed in which water cooling is continued until the temperature reaches 0 to reduce center segregation (JP-A-6-335760).

[0011] When casting a slab having a diameter or thickness of 250 mm or more, the former stage spray zone provided immediately below the mold and the latter stage spray zone for the final stage of solidification provided before completion of solidification on the downstream side
In the secondary cooling performed in two zones, the water amount density is 25 to 100 [liter / (min. ・ M ² )] from the region where the solid fraction in the center of the slab is 0.5 to 0.65 to 0.8 or more. To continue water cooling and reduce center segregation (JP-A-8-19843)
Is proposed.

[0012] When the solid fraction of the slab center portion having a diameter or thickness of 261 mm or less is 0.2 to 0.8, surface cooling of the slab is started by water cooling with a specific water content of 0.1 to 0.41 kg · steel and complete solidification Up to now, there has been proposed a method (Japanese Patent Laid-Open No. 8-332556) for continuing the water cooling with the specific water amount to reduce the center porosity.

[0013]

The previously disclosed method of cooling the surface of the slab and shrinking the slab to reduce center porosity and center segregation has the following problems to be further studied. is there. (1) In the method already disclosed above, the range of appropriate conditions for exhibiting the effect of reducing center porosity and center segregation is extremely narrow, and when this appropriate condition is expressed by the casting speed, it is about ± 100 mm / min. However, when it is used in actual production, the appropriate conditions are easily deviated due to the disturbance of the pinch roll rotation speed measurement error. Therefore, it is necessary to increase the appropriate range. (2) Since the appropriate range is very narrow as described in (1) above, it is necessary to precisely control the cooling start and end positions. (3) The previously disclosed method does not disclose the spraying state of the cooling medium. However,
In order to exert the effect of reducing center porosity and center segregation, cooling must be performed uniformly within the cooling range. Further, if the cooling is not performed uniformly, the slab may be bent due to thermal stress depending on the type of steel, which is not suitable for actual production. (4) The above-disclosed method certainly has the effect of reducing center segregation. However, depending on the type of steel, internal flaws may occur during the production of seamless steel pipe unless further reduced.

[0014] An object of the present invention is to solve the problems of the above-mentioned conventional techniques, and in the continuous casting of various steels such as carbon steel, low-alloy steel, high-low alloy steel, and stainless steel, a center generated in the center of the slab. It is an object of the present invention to provide a method for cooling a slab capable of reducing porosity or center segregation.

[0015]

Means for Solving the Problems The inventors of the present invention have conducted various tests and examinations in order to achieve the above object, and have obtained the following findings. (1) In order to increase the appropriate range for exerting the effect of reducing center porosity and center segregation, increase the water content density of the final solidification forced cooling to cool the surface of the slab more, and use the smaller water content density for the final solidification forced cooling. After starting, the two means of increasing the water density toward the downstream side of casting are effective. (2) To control the start and end positions of forced cooling at the end of solidification, it is simplest to use a fixed forced cooling zone at the end of solidification, determine the final solidification position by solidification calculation considering segregation, and adjust the casting speed. And is suitable for actual production. (3) In the case of flat spraying, it is effective to make the width direction the same as the casting direction in order to achieve uniform spraying of cooling water in the forced cooling zone at the end of solidification. It is also effective to apply a full cone nozzle. (4) In order to further reduce the center segregation, it is effective to physically stir the molten steel in the center of the slab and to disperse the segregation to some extent in advance before the final solidification forced cooling.

The method for cooling a slab according to the present invention is, in continuous casting of a steel bloom or billet, a solid fraction at a position 0.1 to 2.0 m before the leading end of the residual molten metal pool in the casting direction or at the center of the slab. From the position of 0.1 to 0.8 until the solid fraction in the center of the slab becomes 0.99 or more, and the water amount density on the surface of the slab in the forced cooling zone at the final stage of solidification is 10 to 300 liters.
/(Min.·m ² ) and the water density to the downstream side
It is characterized by increasing the water temperature and cooling it with water.

For continuous casting of steel blooms or billets
In addition, the remaining molten metal pool should be in front of the leading edge of the casting direction.
The solid fraction at the position of 1 to 2.0 m or the center of the slab is 0.1
The solid fraction of the center of the slab is 0.99 or more from the position of ~ 0.8
Until the end of solidification, the amount of water on the surface of the slab in the forced cooling zone at the end of solidification
The degree is 10 to 300 liters / (min. · M ² ),
Further, the forced cooling zone at the final stage of solidification is divided into two or more, each cooling zone length is set to 0.2 to 5.8 m , and water cooling is performed by increasing the water amount density of each cooling zone toward the downstream side. To do.

[0018]

[0019]

[0020]

[0021]

[0022]

[0023]

[0024]

[0025]

[0026]

[0027]

[0028]

DESCRIPTION OF THE PREFERRED EMBODIMENTS FIG. 1 is a schematic view showing an example of a process for producing a cast slab by continuous casting according to the present invention. Molten steel 3 injected into the continuous casting mold 2 from the tundish 1 is
It is cooled in the mold 2 and a solidified shell is formed on the outside. The slab 4 pulled out from the mold 2 enters the pinch roll band 6 through the spray cooling band 5 and is spray cooled. Thereafter, the slab 4 is forcedly cooled in the final solidification forced cooling zone 8 via the electromagnetic stirrer 7.

[0029] The forced cooling of the slab in the forced cooling zone at the final stage of solidification is performed by 0.1 to 2.0 before the leading end in the casting direction of the residual molten steel pool.
It is necessary to start from the position m or the position where the solid fraction at the center of the slab is 0.1 to 0.8. This is because the forced cooling start is too early and the shrinkage allowance of the slab center actually increases if the solid fraction of the slab center is less than 2.0m or more than 2.0m in front of the casting direction of the residual molten steel pool. This is because the shrinkage margin of the surface cannot be kept large and the inner quality improvement effect at the center of the slab cannot be exhibited. Further, at a position of less than 0.1 m before the re-tip in the casting direction of the residual molten steel pool or at a position where the solid fraction of the slab center exceeds 0.8, it is too close to the final solidification position to improve the internal quality of the slab center. This is because there is no time to show it.

[0030] The forced cooling of the slab in the forced cooling zone at the end of solidification needs to be finished at a position where the solid fraction of the central portion of the slab is 0.99 or more. This is because if the forced cooling is finished at the position where the solid fraction of the slab center is less than 0.99, the forced cooling is finished before it is completely solidified. This is because, on the contrary, the inner quality of the central portion of the slab is deteriorated.

[0031] Fig. 2 shows that when 1% Cr steel is continuously cast into a billet having a diameter of 200 mm, the length of the forced cooling zone at the end of solidification is 5 m, the water amount density is 100 liters / min.m ² , 300 liters / min.m ² , Casting speed 2.1
The relationship between the center porosity diameter and the casting speed in the case of continuous casting under the condition of 2.8 m / min.
Center porosity ≤ 5 mm is necessary to prevent internal flaws during seamless steel pipe manufacturing.

[0032] When water density in the coagulation end forced cooling zone is less than 100 l / min. · M ^2, as shown in FIG. 2, the casting speed and center porosity ≦ 5 mm is <± 0.1 m /
Must be controlled to min. This is within the error range of the casting speed measurement by the pinch roll, and it is impossible to control the casting speed in actual production. The controllable casting speed range is ≧ ± 0.1 m / min. The increase of the water amount density expands the proper range of the casting speed and becomes ≧ ± 0.1 m / min. Therefore, the casting speed can be controlled in the actual production. The upper limit of the water density 300 l / min. · M ² and was of the water flow rate is 30
This is because if it exceeds 0 liter / min.m ² , the surface of the slab will be overcooled and problems such as bending of the slab will occur.

[0033] FIG. 3 is a diagram illustrating a case where 1% Cr steel is continuously cast into a billet having a diameter of 200 mm, the length of the forced cooling zone at the end of solidification is 5 m, and the casting speed is 2.43 m /
Under the casting conditions of min., the water density is 30 liters / min. ・ m ² , 1
The relationship between the distance from the meniscus, the cooling rate at the center of the slab, and the cooling rate of the skin when changing from 00 liter / min.m ² to 170 liter / min.m ² was investigated. It can be seen that the appropriate range of casting speed is expanded by increasing the water density.

[0034] In order to develop the effect of improving the internal quality of the slab, it is a necessary condition that the cooling rate of the skin, that is, the shrinkage density, exceeds the cooling rate of the slab center, that is, the shrinkage density. As shown in FIG. 3, Yotsute to a water density ≧ 100 liters / min. · M ^2, the cooling rate of the cooling rate> billet center of the skin are achieved, the slab inner quality improving effect The expression is confirmed.

[0035] FIG. 4 shows that when 1% Cr steel is continuously cast into a billet having a diameter of 200 mm, the length of the forced cooling zone at the end of solidification is 5 m, the water density is 100 liters / min.m ² , 170 liters / min.m ² In the final stage of solidification, the water volume density of the forced cooling zone length 3.5m, the first 0.8m 65 liters
/ min. ・ m ² , the latter 2.7m was 170 liters / min. ・ m ² , and the relationship between the center porosity diameter and the casting speed when continuously cast at the casting speed of 1.9 to 2.9 m / min. Is. Center porosity ≤ 5 mm is a necessary level to prevent internal flaws during seamless steel pipe manufacturing.

[0036] As shown in Fig. 4, when the water amount density of the final solidification forced cooling zone is increased toward the rear in the casting direction, it is also possible to increase the appropriate range of the casting speed. This is because it is possible to maintain a high cooling rate in the surface of the cast slab by further performing forced cooling when the cooling rate has decreased.

[0037] This means that 1% Cr steel is used as a billet with a diameter of 200 mm.
When continuously casting, the front stage 0.8m with 3.5m length of cooling zone at the end of solidification
65 l / min.m², 2.7 liters in the latter stage is 170 liters / min.m
², Casting speed 2.10m / min., 2.75m / min. Continuous casting
Distance from the meniscus and cooling speed of the center of the slab
The relationship between the temperature and the cooling rate of the epidermis was also investigated.
It is.

[0038] The minimum value of the divided final solidification forced cooling zone length is 0.
The reason why the minimum value of the water amount density is 2 liters and 10 liters / min.m ² is that if it is more than this, the cooling rate of the skin> the cooling rate of the central portion of the slab can be realized.

[0039] At any position between immediately before the forced cooling zone at the end of solidification and between the lower end of the mold, electromagnetic stirring is performed in the casting direction or in a direction perpendicular to the casting direction to disperse the center segregation to some extent in advance. As shown in 6, it is possible to reduce the occurrence rate of inner surface flaws in the seamless steel pipe.

[0040] In the case of a slab having a diameter or a thickness of 320 mm or less, the heat transfer resistance is small, so that the effect of improving the inner quality of the slab center portion is greater.

[0041] If the length of the forced cooling zone at the end of solidification exceeds 6 m, supercooling of the slab occurs, and bending occurs depending on the steel type, which is not suitable for actual production. Therefore, it is desirable that the total length of the forced cooling zone in the final stage of solidification is 6 m or less.

[0042] Cooling in the forced cooling zone at the final stage of solidification is more preferable if it is carried out by an air mist sprayer because a larger cooling capacity can be obtained as compared with water cooling.

When the flat type is used as the spray nozzle for the forced cooling zone in the final stage of solidification, as shown in FIG. 7, the spray width direction of the nozzle 71 is set to the casting direction indicated by the arrow of the cast piece 72, so that Uniform cooling is possible. As a result, it is possible to stabilize the effect of improving the internal quality, and it is also possible to suppress the occurrence of bending of the slab. When the full cone type is applied, more uniform cooling is achieved, so a more desirable internal quality improvement effect is obtained.

[0044] The surface temperature of the slab on the inlet side of the forced cooling zone at the end of solidification is 85
It must be 0 ° C or higher. Below 850 ° C, coagulation has already progressed, and no improvement in the internal quality is observed. The surface temperature of the slab on the exit side of the forced cooling zone at the end of solidification is 700 ° C.
Must be: This is because the cooling rate of the surface of the slab cannot exceed the cooling rate of the central portion of the slab without such cooling.

[0045] In order to obtain the casting cutting edge position of the residual molten steel pool of the round billet, the general cylindrical differential equation for heat conduction in the following equation (1) is solved, and the central portion of the round billet slab considering segregation is solved. When the time at which the phase ratio reaches 0.99 is obtained, the most advanced position of the residual molten steel pool in the casting direction can be obtained from the casting speed. Therefore, by adjusting the casting speed, as shown in FIG. 8, the hit rate at which the proper range cooling is obtained becomes 100%, and the effect of improving the internal quality is stabilized.

[0046]

[Equation 1]

The combined use of electromagnetic stirring in the mold increases the equiaxed crystal ratio and enables dispersion of center segregation, so that an effect of improving the internal quality is further recognized.

[0048] By terminating the casting of the molten steel at the same constant speed as the steady portion, good quality can be ensured even in the unsteady cast piece in the final casting.

[0049]

EXAMPLES Using an arc curved type continuous casting machine of equal curvature radius 10m to the structure shown in FIG. 1, installed coagulation end forced cooling zone from 27.5m from Meni <br/> scan mosquito scan the position of 34.5m Then
A round billet slab was cast by a continuous casting mold having a circular cross section and a diameter of 200 mm. The casting steel type is a low carbon steel having the chemical composition shown in Table 1, and the casting speed is 2.0 to 2.7 m / mi.
n. , The specific water content of the secondary cooling zone immediately after the mold is 0.05 to 0.
It was 8 liters / kg · steel. The casting conditions are shown in Tables 2 and 3, and the casting results are shown in Table 4. Moreover, the obtained round billet slab was used for manufacturing a seamless steel pipe, and the occurrence rate of inner surface flaws in the seamless steel pipe was investigated. The results are shown in Table 4.

[0050] In Tables 2 and 3, Vc represents the casting speed, center fs represents the central solid fraction, and Lp represents the distance from the front end in the casting direction of the residual molten metal pool. Further, the center porosity area fraction (%) in Table 4 was determined by (porosity area) / (cast piece area) × 100 measured from the billet cross-section macro sample. The center segregation degree C / C ⁰ was determined by [C] analysis of 1/4 part of the billet cross-section macro sample and a drill sample with a diameter of 5 mm taken from the center part, (center C concentration) / (1 / 4 part C concentration). The occurrence rate of inner surface flaws in the seamless steel pipe was obtained by performing visual inspection and ultrasonic flaw detection test, and calculating (number of inner surface flaws) / (number of pipes manufactured) × 100.

[0051]

【table 1】

[0052]

[Table 2]

[0053]

[Table 3]

[0054]

[Table 4]

[0055] As shown in Tables 2 to 4, the actual Example 1 is carried out the division of the forced cooling zone, water density 5 at the front stage 2m
0 l ^{/ (min. · M 2)} , and a water flow rate 150 l later ^{3m / (min. · M 2} ). Example 1
In No. 3 , good slab quality was obtained. Reference example 1
Is the forced cooling start position, forced cooling end position, forced cooling zone
The length and water density are sufficient and good slab quality is obtained.
It In Reference Example 2 , an electromagnetic stirrer was installed immediately before the forced cooling zone and the electromagnetic stirrer was carried out, and a remarkable improvement in the center segregation degree is recognized. In Reference Example 3 , air mist spray was used as the cooling method, and good slab quality was obtained.

[0056]referenceAn exampleFourIs a spray nozzle
It is a type that uses a slab type to obtain good slab quality.
There is.referenceAn example5Is the residual solution by the solidification calculation of the above formula (1)
Predicting the foremost position in the casting direction of the steel pool,
It has been adjusted, and along with stabilizing the effect of improving the internal quality,
Naturally, good slab quality has been obtained.referenceAn example6
Is the result of electromagnetic stirring in the mold.
Goodness is recognized.referenceAn example7Is the same as the steady part when pouring is completed.
It was drawn at one constant speed, and
Even if it is, good slab quality is obtained.

[0057] On the other hand, in Comparative Example 1, the cooling start position was as slow as 0.05 m from the foremost position in the casting direction of the residual molten steel pool, and therefore center porosity and center segregation had already occurred, so the internal quality improvement effect was Not observed, and the rate of occurrence of internal flaws is high in seamless steel pipes. In Comparative Example 2, the cooling end position is early, tensile stress is generated in the center of the slab due to expansion of the slab skin due to reheat, and both center porosity and center segregation are deteriorated. Naturally, the rate of occurrence of internal flaws in seamless steel pipes is also very high.

[0058] Comparative Example 3 is a slab because the forced cooling zone is as long as 7 m.
Was overcooled and bent, and it did not become a product. ratio
In Comparative Example 4, the water volume density in the forced cooling zone is 90 liters / (min.m
²), The effect of improving the internal quality is not recognized. Comparative example
5 has a water volume density of 400 liters / (min.²)
Since it is too large, the slab is overcooled and bends,
It did not become a product.

[0059]

The method of cooling a slab in continuous casting according to the present invention is a center of the slab in the continuous casting of various steel slabs such as carbon steel, low alloy steel, high low alloy steel, and stainless steel. Porosity or center segregation can be reduced, and generation of inner surface flaws in a seamless steel pipe made of a steel slab can be suppressed.

[Brief description of drawings]

FIG. 1 is a schematic diagram showing an outline of continuous casting equipment used in Examples.

FIG. 2 is a graph showing the relationship between the water content density, the casting speed, and the center porosity diameter in the final solidification forced cooling zone.

FIG. 3 is a graph showing the relationship between the distance from the meniscus, the cooling rate of the steel slab center and the skin, and the water amount density.

FIG. 4 is a graph showing the relationship among water amount density, casting speed, and center porosity diameter.

FIG. 5 is a graph showing the relationship between the distance from the meniscus, the cooling rate of the steel slab center and the skin, and the water amount density.

FIG. 6 is a graph showing the relationship between the presence or absence of electromagnetic stirring immediately before the forced cooling zone in the final stage of solidification and the occurrence rate of inner surface flaws in the seamless steel pipe.

7A and 7B are schematic views in the case where the width direction of the flat spray is the same as the casting direction, FIG. 7A is a side view, and FIG. 7B is a plan view.

FIG. 8 is a graph showing the relationship between the presence or absence of execution of casting speed control by estimating the most distal position of the remaining molten metal pool in the casting direction and the appropriate ratio accuracy.

[Explanation of symbols]

1 tundish 2 molds 3 Molten steel 4,72 slab 5 Spray cooling zone 6 pinch roll belt 7 Electromagnetic stirrer 8 Final solidification forced cooling zone 71 nozzles

─────────────────────────────────────────────────── --Continued from the front page (56) References JP-A-8-332556 (JP, A) JP-A-11-216551 (JP, A) JP-A-11-192539 (JP, A) JP-A-59- 159257 (JP, A) JP 60-245718 (JP, A) JP 9-314289 (JP, A) JP 8-19843 (JP, A) JP 63-165053 (JP, A) JP-A-7-1096 (JP, A) JP-A-8-150451 (JP, A) JP-A-6-335760 (JP, A) JP-A-10-128510 (JP, A) JP-A-2-15856 (JP, A) (58) Fields investigated (Int.Cl. ⁷ , DB name) B22D 11/124 B22D 11/22

Claims (4)

(57) [Claims] 1. Continuous bloom or billet casting of steel
In addition, the remaining molten metal pool should be in front of the leading edge of the casting direction.
From 1 to 2.0 m, the solid fraction of the slab center is 0.99.
Until the above, water on the surface of the slab in the forced cooling zone at the end of solidification
Volume density of 10 to 300 liters / (min. · M ² )
And, and increases as comprising a water amount density on the downstream side of water-cooled
Slab method of cooling in continuous casting characterized by the retirement. 2. Continuous blooming or billet casting of steel
The solid fraction at the center of the slab is 0.1 to 0.8
Solidification until the solid fraction of the center of the slab becomes 0.99 or more
The water content density on the surface of the slab in the final forced cooling zone is set to 10 to 300.
Liters / (min. · M ²⁾ and was, and, to characterized in that the water amount density is increased as will downstream water cooling
Cooling method of communicating cast in connection cast piece that. 3. For continuous casting of steel blooms or billets.
In addition, the remaining molten metal pool should be in front of the leading edge of the casting direction.
From 1 to 2.0 m, the solid fraction of the slab center is 0.99.
Until the above, the amount of water on the surface of the slab in the forced cooling zone at the end of solidification
Density of 10 to 300 liters / (min. · M ² )
In addition, the end solidification forced cooling zone is divided into two or more to make each cooling zone length 0.2 to 5.8 m, and water cooling is performed by increasing the water amount density of each cooling zone toward the downstream side. method of cooling the slab in continuous casting it <br/> characterized. 4. Continuous casting of bloom or billet of steel
The solid fraction at the center of the slab is 0.1 to 0.8
Solidification until the solid fraction of the center of the slab becomes 0.99 or more
In the final forced cooling zone, the water content density on the surface of the slab is adjusted to 10 to 300 liters.
Tull / (min. · M ² ), and the final solidification forced cooling zone is divided into two or more, and the length of each cooling zone is 0.2 to 5.
And 8m, slab method of cooling in continuous casting you characterized in that the water density of the cooling zone is increased as will downstream water cooling.