EP3998126A1 - Procédé de refroidissement secondaire et appareil de refroidissement secondaire pour brame de coulée continue - Google Patents

Procédé de refroidissement secondaire et appareil de refroidissement secondaire pour brame de coulée continue Download PDF

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Publication number
EP3998126A1
EP3998126A1 EP20836022.2A EP20836022A EP3998126A1 EP 3998126 A1 EP3998126 A1 EP 3998126A1 EP 20836022 A EP20836022 A EP 20836022A EP 3998126 A1 EP3998126 A1 EP 3998126A1
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EP
European Patent Office
Prior art keywords
cooling
cast slab
cooling water
zone
flow density
Prior art date
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Pending
Application number
EP20836022.2A
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German (de)
English (en)
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EP3998126A4 (fr
Inventor
Hirokazu Sugihara
Kenichi OSUKA
Satoshi Ueoka
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JFE Steel Corp
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JFE Steel Corp
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Publication date
Application filed by JFE Steel Corp filed Critical JFE Steel Corp
Publication of EP3998126A1 publication Critical patent/EP3998126A1/fr
Publication of EP3998126A4 publication Critical patent/EP3998126A4/fr
Pending legal-status Critical Current

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    • B—PERFORMING OPERATIONS; TRANSPORTING
    • 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
    • B22D11/225—Controlling or regulating processes or operations for cooling cast stock or mould for secondary cooling
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • 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
    • B22D11/12—Accessories for subsequent treating or working cast stock in situ
    • B22D11/124—Accessories for subsequent treating or working cast stock in situ for cooling
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • 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
    • B22D11/12—Accessories for subsequent treating or working cast stock in situ
    • B22D11/124—Accessories for subsequent treating or working cast stock in situ for cooling
    • B22D11/1241—Accessories for subsequent treating or working cast stock in situ for cooling by transporting the cast stock through a liquid medium bath or a fluidized bed
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • 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
    • B22D11/12—Accessories for subsequent treating or working cast stock in situ
    • B22D11/124—Accessories for subsequent treating or working cast stock in situ for cooling
    • B22D11/1246—Nozzles; Spray heads

Definitions

  • the present invention relates to a secondary cooling method and a secondary cooling apparatus for a continuously cast slab while a cast slab is subjected to secondary cooling in a secondary cooling zone of a continuous casting machine.
  • molten steel poured into a mold is cooled by the mold and forms a solidifying shell at a contact surface that is in contact with the mold.
  • a cast slab including the solidifying shell, which serves as an outer shell, and unsolidified molten steel in the shell is continuously pulled downward from the mold while being cooled with cooling water in a secondary cooling zone provided below the mold, and is eventually solidified entirely to the center.
  • the cast slab that has been solidified entirely to the center is cut to a predetermined length to produce a cast slab that serves as a rolling material.
  • the cast slab In secondary cooling, the cast slab is generally cooled in a film boiling state.
  • film boiling is one of boiling regimes that easily occurs when an object having a high surface temperature is cooled with low-pressure cooling water supplied at a low flow rate. A layer of vapor is generated between the cooling water and the cooled object, and the cooling rate at which the object is cooled is relatively low. Although this enables reliable cooling of the object, there is a problem that the productivity is low.
  • the cooling water may be sprayed against the surface of the cast slab at a high pressure, so that a larger amount of cooling water comes into contact with the surface of the cast slab per unit time. As a result, the coefficient of heat transfer is increased, and the productivity is increased accordingly.
  • NPL 1 J.V. BECK, Int. J. Mass Transfer, 13 (1970), p. 703
  • Patent Literature 1 requires additional equipment, such as additional pumps and high pressure resistant pipes, and the cost is increased.
  • the present invention has been made to solve the above-described problem, and an object of the present invention is to provide a secondary cooling method and a secondary cooling apparatus for a continuously cast slab by which secondary cooling can be efficiently performed without a large capital investment.
  • the second cooling step may be performed such that when a thickness of the cast slab is t (m), an average thermal conductivity of the cast slab in a thickness direction in a region excluding an unsolidified portion of the cast slab is ⁇ (kcal/(m ⁇ hour ⁇ °C)), and a solidification temperature of the cast slab is Tc (°C), a heat flux q (kcal/(m 2 ⁇ hour)) of the cooling water satisfies a relationship of Expression (2).
  • the second cooling step may be performed such that the flow density W of the cooling water satisfies a relationship of Expression (3) .
  • W > e ⁇ log ⁇ 4 Tc ⁇ Ts / t ⁇ 5.2 / 0.17
  • e is a base of a natural logarithm
  • log is a common logarithm
  • ⁇ is an exponentiation operator in Expression (3).
  • a plurality of rollers and a plurality of spray nozzles may be provided in the horizontal zone, the rollers being arranged in the casting direction and oriented so that axial directions thereof are perpendicular to the casting direction, the spray nozzles which discharge the cooling water toward the surface of the cast slab being arranged in a cast slab width direction between the rollers that are adjacent to each other in the casting direction.
  • a cooling surface formed when the cooling water discharged from each of the spray nozzles strikes the surface of the cast slab has a round cornered rectangular shape or an elliptical shape.
  • the cooling water is discharged such that a major axis of the cooling surface is inclined at an angle in a range of 5 to 45 degrees relative to a direction perpendicular to the casting direction.
  • a secondary cooling apparatus for a continuously cast slab is an apparatus by which a cast slab cast in a continuous casting machine is subjected to secondary cooling in a secondary cooling zone including a vertical zone, a curved zone, and a horizontal zone, and the horizontal zone includes a first cooling portion and a second cooling portion.
  • the cast slab is able to be cooled with cooling water supplied at a flow density per unit time of 300 to 4000 liter/(m 2 ⁇ min) (where min means minute as a unit of time) so that the cooling water on a surface of the cast slab is in a nucleate boiling state in the first cooling portion.
  • the cast slab is cooled with the cooling water supplied at a flow density per unit time of 2% or more and 50% or less of the flow density of the cooling water in the first cooling portion so that the nucleate boiling state of the cooling water on the surface of the cast slab is maintained in the second cooling portion.
  • a plurality of rollers and a plurality of spray nozzles are provided in the horizontal zone, the rollers being arranged in the casting direction and oriented so that axial directions thereof are perpendicular to the casting direction, the spray nozzles which discharge the cooling water toward the surface of the cast slab being arranged in a cast slab width direction between the rollers that are adjacent to each other in the casting direction.
  • the spray nozzles are able to discharge the cooling water so that a cooling surface formed when the cooling water discharged from each of the spray nozzles strikes the surface of the cast slab has a round cornered rectangular shape or an elliptical shape.
  • the spray nozzles are arranged such that a major axis of the cooling surface is inclined at an angle in a range of 5 to 45 degrees relative to a direction perpendicular to the casting direction.
  • the first cooling step is performed such that a flow density per unit time of the cooling water is 300 to 4000 liter/(m 2 ⁇ min) so that the cooling water on the surface of the cast slab is in the nucleate boiling state in the first cooling portion.
  • the second cooling step is performed such that the flow density is 2% or more and 50% or less of that in the first cooling step so that the nucleate boiling state of the cooling water on the surface of the cast slab is maintained.
  • a secondary cooling method for a continuously cast slab is a method by which a cast slab 3 cast by a continuous casting machine 1 is subjected to secondary cooling in a secondary cooling zone 11 including a vertical zone 5, a curved zone 7, and a horizontal zone 9.
  • the horizontal zone 9 includes a first cooling portion 13 in which a first cooling step is performed and a second cooling portion 15 in which a second cooling step is performed.
  • the continuous casting machine 1 is an apparatus in which molten steel poured into a mold 17 from a tundish (not illustrated) is supported by rollers 19 and pulled out in the form of the cast slab 3 while being subjected to secondary cooling by cooling sprays 21 disposed between the rollers 19.
  • the secondary cooling zone 11 in which the cast slab 3 is subjected to secondary cooling, is sectioned into the vertical zone 5, the curved zone 7, and the horizontal zone 9.
  • the secondary cooling method of the present invention relates to a method for cooling the cast slab 3 in the horizontal zone 9.
  • the cast slab 3 is cooled with cooling water supplied by the cooling sprays 21 at a flow density per unit time of 300 to 4000 liter/(m 2 ⁇ min) (where min means minute as a unit of time) so that the cooling water on the surface of the cast slab 3 is in a nucleate boiling state in the first cooling portion 13.
  • the flow density per unit time of the cooling water in the first cooling portion 13 is a value calculated by dividing the total amount of cooling water (liter/min) in the first cooling portion 13 by the area (m 2 ) of the first cooling portion 13.
  • the cooling sprays 21 are devices that spray liquid or a mixture of liquid and gas over the surface of the cast slab 3.
  • An example of liquid is water, and an example of gas is air.
  • the cooling sprays 21 are disposed between the rollers 19 that convey the cast slab 3 in a casting direction.
  • each cooling spray 21 includes a plurality of spray nozzles 23 arranged in a width direction of the cast slab 3 in a region between the rollers 19.
  • the spray nozzles 23 illustrated in Fig. 2 are flat spray nozzles.
  • Each flat spray nozzle discharges refrigerant 25, which serves as the cooling water, in the form of a fan that spreads in the cast slab width direction with the spray nozzle 23 at the center. Therefore, a striking surface in which the cooling water strikes the surface of the cast slab has an elongated linear shape with a small width in the casting direction and a large width in the cast slab width direction.
  • the elongated linear shape of the striking surface in which the cooling water discharged from each flat spray nozzle strikes the surface of the cast slab is referred to as a "round cornered rectangular shape".
  • the type of the spray nozzles 23 is not particularly limited, and sprays having nozzles similar to the flat spray nozzles may instead be used.
  • sprays include oval spray nozzles (elliptical sprays or oval sprays), full cone spray nozzles (cone sprays or round sprays), which are nozzles that discharge cone-shaped jets, or nozzles that discharge quadrangular-pyramid-shaped jets, such as square sprays (quadrangular sprays, square sprays, or rectangular sprays), which are quadrangular full cone sprays.
  • each nozzle is typically disposed such that the major axis of the cooling surface (striking surface in which the cooling water strikes the surface of the cast slab), which has a round cornered rectangular shape or an elliptical shape, is perpendicular to the casting direction.
  • the spray nozzles 23 are arranged in the width direction of the cast slab 3 in each of the regions between the rollers 19.
  • the cooling water discharged from the spray nozzles 23 flows along the surface of the cast slab 3 at a high velocity in the direction of the major axis of the striking surface in which the cooling water strikes the surface of the cast slab 3 (hereinafter referred to as a spray width direction) and at a relatively low velocity in the direction of the minor axis of the striking surface (hereinafter referred to as a spray thickness direction). Therefore, after striking the surface of the cast slab, the cooling water relatively gently spreads in the spray thickness direction, that is, in the casting direction.
  • jets of cooling water discharged from adjacent sprays strike each other at velocities in the opposite directions at the ends thereof, and then change the directions thereof so as to spread in the casting direction.
  • the cooling water flows in the casting direction along the surface of the cast slab at a relatively slow velocity after striking the surface of the cast slab.
  • the major axis of the cooling surface When the major axis of the cooling surface is inclined relative to the direction perpendicular to the casting direction, interference between the jets of cooling water discharged from the adjacent sprays occur in the spray thickness direction, in which the velocity is relatively low, and does not occur in the spray width direction, in which the velocity is high. Therefore, the cooling water flows along the surface of the slab at a high velocity.
  • the cooling capability is increased as the velocity of the cooling water is increased. Therefore, the cooling capability is increased when each spray nozzle 23 is disposed such that the major axis of the cooling surface is inclined relative to the direction perpendicular to the casting direction. Assuming that the angle of the direction perpendicular to the casting direction is 0 degrees, the major axis of the cooling surface is preferably inclined at an angle in the range of 5 to 45 degrees.
  • cooling is performed at a flow density per unit time of 300 to 4000 liter/(m 2 ⁇ min) so that the cooling water is in a nucleate boiling state on the entirety or at least a portion of the surface of the cast slab 3.
  • strong cooling When the cast slab is cooled at a high coefficient of heat transfer (hereinafter referred to as strong cooling) before the cast slab enters the horizontal zone 9, there is a high risk that cracking will occur, in particular, in a corner portion of the cast slab 3. Therefore, strong cooling may be performed in the horizontal zone 9.
  • the flow rate of the cooling water used during strong cooling needs to be reduced to reduce the capital investment. Accordingly, a method of supplying the cooling water at a high flow rate only in the first cooling step and supplying the cooling water at a low flow rate in the second cooling portion 15 has been studied.
  • Fig. 4 is a graph showing the relationship between the flow rate of the cooling water, the surface temperature of the cast slab 3, and the cooling capability.
  • the vertical axis represents the cooling capability, and the horizontal axis represents the surface temperature of the cast slab.
  • the graph shows three cases in which the flow rate of the cooling water is high, middle, and low.
  • the temperature region at or below the local maximum point of the cooling capability is a nucleate boiling region
  • the temperature region at or above the local minimum point of the cooling capability is a film boiling region.
  • Nucleate boiling is a boiling state in which bubbles are generated from bubble formation points serving as nucleuses and in which the cooling water is capable of extracting a very large amount of heat from a cooling object.
  • Film boiling is a boiling state in which a film of vapor is formed at the boundary between the cooling water and the cooling object and serves as a thermal barrier that reduces the amount of heat that can be extracted from the cooling object by the cooling water.
  • the flow rate of the cooling water generally changes as shown by the empty arrows in Fig. 4 .
  • cooling at a high flow rate in the first cooling step is performed such that the flow density per unit time is 300 to 4000 liter/(m 2 ⁇ min). The reason for this will now be described.
  • the local minimum value of the cooling capability varies depending on the flow rate. Studies conducted by the present inventors have shown that when the flow density per unit time is 300 liter/(m 2 ⁇ min), a temperature giving a local minimum value of the cooling capability is about 1000°C.
  • the surface temperature of the cast slab 3 in the horizontal zone 9 is 1000°C or less, which is in a temperature region lower than the temperature at which the cooling capability is at the local minimum. Therefore, when the flow density per unit time is 300 liter/(m 2 ⁇ min), cooling of the cast slab 3 in the horizontal zone 9 can be started with cooling capability higher than the cooling capability at the local minimum.
  • the inventors have found that when the flow density is greater than or equal to 4000 liter/(m 2 ⁇ min), the cooling capability hardly changes in response to an increase in the flow density per unit time, and the cooling water cannot be effectively used.
  • cooling at the high flow rate in the first cooling portion 13 is performed such that the flow density per unit time is 300 to 4000 liter/(m 2 ⁇ min).
  • a more preferred range of the flow rate is 300 to 2000 liter/(m 2 ⁇ min).
  • cooling is performed at a high flow rate in the first cooling step so that the surface temperature of the cast slab 3 is reduced and that nucleate boiling is achieved during the first cooling step, and nucleate boiling is maintained at a low flow rate in the subsequent second cooling step. Conditions for achieving such performance in these steps will now be discussed.
  • W is the flow density per unit time (liter/(m 2 ⁇ min)) and ln is a natural logarithm.
  • cooling may be performed at a high flow rate so that the temperature is reduced to a temperature lower than Ts given above depending on the flow density per unit time in the second cooling step.
  • cooling in the first cooling step may be performed so that the surface temperature Ts (°C) of the cast slab 3 at the time when cooling in the second cooling step is started satisfies Expression (1).
  • Ts ⁇ 10 ⁇ 0.08 ⁇ ln W + 2
  • the cast slab 3 is cooled with cooling water at a flow density per unit time of 2% or more and 50% or less of that in the first cooling step so that the nucleate boiling state of the cooling water on the surface of the cast slab 3 is maintained.
  • the flow density per unit time of the cooling water in the second cooling portion 15 is a value calculated by dividing the total amount of cooling water (liter/min) used in the second cooling portion 15 by the area (m 2 ) of the second cooling portion 15.
  • the first cooling step when the first cooling step is performed such that the surface temperature of the cast slab 3 at the start of the second cooling step satisfies Expression (1) given above, cooling can be performed in the second cooling step while nucleate boiling is maintained at a low flow density, that is, the flow density per unit time W given in Expression (1).
  • the flow density per unit time may be set to 2% or more and 50% or less of that in the first cooling step. A more preferred range of the flow density per unit time is 5% to 20% of that in the first cooling step.
  • the surface temperature of the cast slab increases due to a heat flux generated by the heat capacity of the inner part of the cast slab 3.
  • the temperature increase needs to be reduced to maintain the surface temperature of the cast slab at the above-described temperature. This is because if the surface temperature exceeds the temperature at which the cooling capability is at a local maximum, the dependency of the cooling capability on the flow rate increases, and high cooling capability cannot be achieved at a low flow rate.
  • the temperature increase can be reduced to maintain the surface temperature of the cast slab at the above-described temperature when a heat flux of the jets of cooling water from the outside of the cast slab 3 is greater than the heat flux generated by the heat capacity of the inner part of the cast slab 3.
  • the temperature distribution of the cast slab 3 has the maximum temperature at the center in the thickness direction and can be approximated by a parabola. Therefore, the recuperated heat flux q' (kcal/(m 2 ⁇ hour)) can be expressed by Expression (4).
  • q ′ ⁇ 4 Tc ⁇ Ts / t
  • t is the thickness (m) of the cast slab
  • ⁇ is the average thermal conductivity (kcal/(m ⁇ hour ⁇ °C)) in the thickness direction in a region excluding an unsolidified portion of the cast slab
  • Tc is the solidification temperature (°C) of the cast slab.
  • the heat flux q (kcal/(m 2 ⁇ hour)) during cooling may be set to satisfy q ⁇ q', that is, Expression (2).
  • q ⁇ ⁇ 4 Tc ⁇ Ts / t The temperature at the center of the cast slab in the thickness direction is difficult to measure, and is generally around the solidification temperature of the cast slab 3. Therefore, the solidification temperature is used.
  • the inventors have studied the flow density per unit time required to achieve cooling with the heat flux that satisfies Expression (2) given above.
  • the first cooling step is performed at a high flow density so that the cooling water on the surface of the cast slab 3 is in a nucleate boiling state.
  • the second cooling step is performed at a flow density per unit time of 2% or more and 50% or less of that in the first cooling step so that the nucleate boiling state of the cooling water on the surface of the cast slab 3 is maintained.
  • the above-described secondary cooling method for a continuously cast slab may be implemented by a secondary cooling apparatus in which the horizontal zone 9 includes the first cooling portion 13 and the second cooling portion 15.
  • the flow density per unit time is set to 300 to 4000 liter/(m 2 ⁇ min) so that the cooling water on the surface of the cast slab 3 is in a nucleate boiling state.
  • the flow rate is set to 2% or more and 50% or less of that in the first cooling portion 13 so that the nucleate boiling state of the cooling water on the surface of the cast slab 3 is maintained.
  • the nucleate boiling state of the cooling water may be maintained by, for example, measuring the temperature of the cooling water before and after cooling of the cast slab 3, estimating the boiling mode of the cooling water by using the value of the temperature increase of the cooling water, and adjusting the amount of cooling water so that the estimated boiling mode continues to be nucleate boiling. Comparing nucleate boiling and film boiling, the heat flux is greater in nucleate boiling. Therefore, the temperature increase of the cooling water during nucleate boiling is greater than the temperature increase of the cooling water during film boiling.
  • the temperature increase of the cooling water can be estimated by Expression (6). Since a portion of heat is consumed as heat of vaporization, the temperature increase of the cooling water obtained by Expression (6) is an approximate value.
  • ⁇ T q / ⁇ cW
  • ⁇ T the temperature increase (°C) of the cooling water
  • q the heat flux (W ⁇ m 2 ) from the cast slab to the cooling water
  • ⁇ the density (kg/m 3 ) of the cooling water
  • c is the specific heat (J/(kg ⁇ K)) of the cooling water
  • W is the flow density per unit time (m 3 /(m 2 ⁇ s)) of the cooling water.
  • the value of the heat flux q differs between nucleate boiling and film boiling. Therefore, the value of the temperature increase ⁇ T of the cooling water estimated by Expression (6) given above also differs between nucleate boiling and film boiling. Accordingly, the boiling mode of the cooling water can be estimated depending on whether the actual temperature increase, which is determined from the measured temperature values of the cooling water obtained before and after cooling of the cast slab 3, is closer to the estimated value of the temperature increase for nucleate boiling or that for film boiling based on Expression (6) given above.
  • the nucleate boiling state of the cooling water may be maintained by adjusting the amount of cooling water so that the estimated boiling mode may be kept nucleate boiling state.
  • the length of the continuous casting machine 1 was 45 m, and the horizontal zone 9 was constituted by fifteen segments, each having a length of 2 m.
  • the casting speed was 2 mpm
  • the thickness of the cast slab was 250 mm
  • the width of the cast slab was 1500 mm.
  • Water used as the cooling water was mixed with air and was discharged from the cooling sprays 21.
  • the temperature of the water and air was 30°C.
  • the surface temperature of the cast slab 3 was 850°C at the time when the cast slab 3 reached the horizontal zone 9.
  • the solidification temperature, or the solidus temperature was 1500°C, and the average thermal conductivity was 39.4 kcal/(m ⁇ hour ⁇ °C).
  • a radiation thermometer was used to measure the temperature.
  • the solidification position was determined from a rivet driving test.
  • Cooling conditions in the horizontal zone 9 were changed in various ways under the above-described conditions.
  • the first cooling portion 13 and the second cooling portion 15 were partitioned based on the segments, and the flow density per unit time was set for each segment.
  • the heat flux was determined by calculation based on the result of an experiment corresponding to actual operation conditions performed by using an experimental apparatus assembled simulating the actual apparatus. More specifically, in the above-described experiment, the surface temperature of the cast slab was measured by using the radiation thermometer, and the position of the solidification interface was measured by using an ultrasonic wave measurement device. Then, the results of the measurements were used to calculate the heat flux by an inverse heat flux calculation method described in Non Patent Literature 1.
  • the flow density per unit time in the horizontal zone 9 was set to a constant value of 180 liter/ (m 2 ⁇ min).
  • the horizontal zone 9 was set so that five segments at an upstream side thereof constituted the first cooling portion 13 and that the remaining ten segments constituted the second cooling portion 15, and cooling was performed by setting the flow density per unit time individually.
  • cooling at a flow density per unit time of 250 liter/(m 2 ⁇ min) was performed in the five segments in the first cooling portion 13, and the flow density per unit time was reduced to 140 liter/(m 2 ⁇ min) for cooling in the remaining ten segments in the second cooling portion 15.
  • the surface temperature of the cast slab 3 was 763°C.
  • the numbers of segments and the flow density per unit time in the first cooling portion 13 and the second cooling portion 15 were set individually, and cooling was performed.
  • cooling was performed at a flow density per unit time of 300 liter/(m 2 ⁇ min) in five segments in the first cooling portion 13, and at a flow density per unit time of 150 liter/(m 2 ⁇ min) in the remaining ten segments in the second cooling portion 15.
  • the surface temperature of the cast slab 3 at the start of second cooling was 140°C.
  • each spray nozzle is oriented so that the major axis of the cooling surface extends in a direction perpendicular to the casting direction, as illustrated in Fig. 2 .
  • Comparative Example 1 180 (5) (791) 180 100% 260 2.68 5.05 19.3 1.0 Comparative Example 2 250 5 763 140 56% 249 3.40 5.23 21.1 1.5 Comparative Example 3 700 5 95 90 13% 229 4.81
  • the flat spray nozzles installed in the horizontal zone 9 were oriented so that the major axis of the cooling surface having a round cornered rectangular shape formed on the surface of the cast slab by the cooling water discharged from each spray nozzle was inclined relative to the direction perpendicular to the casting direction.
  • the major axis of the cooling surface having a round cornered rectangular shape formed on the surface of the cast slab by the cooling water discharged from each of the spray nozzles in the horizontal zone 9 was inclined at an angle of 20° relative to the direction perpendicular to the casting direction. Cooling was performed at a flow density per unit time of 300 liter/(m 2 ⁇ min) in five segments in the first cooling portion 13, and at a flow density per unit time of 150 liter/(m 2 ⁇ min) in the remaining ten segments in the second cooling portion 15.
  • the surface temperature of the cast slab 3 at the start of second cooling was 128°C.
  • the flow density per unit time was 1000 liter/(m 2 ⁇ min) in the first cooling portion 13, and was 100 liter/(m 2 ⁇ min) in the second cooling portion 15.
  • the major axis was inclined at an angle of 20°.
  • the cooling capability may be increased when the major axis of the cooling surface having a round cornered rectangular shape formed on the surface of the cast slab by the cooling water discharged from each spray nozzle is inclined at an angle in a certain range (5 to 45 degrees) relative to the direction perpendicular to the casting direction.
  • the preferred range of the inclination angle is set to 5 to 45 degrees because the effect is small when the inclination angle is less than 5 degrees and the cooling capability is reduced when the angle exceeds 45 degrees, as suggested in the above-described case in which the angle is 60 degrees.

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  • Engineering & Computer Science (AREA)
  • Mechanical Engineering (AREA)
  • Continuous Casting (AREA)
EP20836022.2A 2019-07-11 2020-07-06 Procédé de refroidissement secondaire et appareil de refroidissement secondaire pour brame de coulée continue Pending EP3998126A4 (fr)

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JP2019128852 2019-07-11
PCT/JP2020/026487 WO2021006253A1 (fr) 2019-07-11 2020-07-06 Procédé de refroidissement secondaire et appareil de refroidissement secondaire pour brame de coulée continue

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EP3998126A1 true EP3998126A1 (fr) 2022-05-18
EP3998126A4 EP3998126A4 (fr) 2022-09-14

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EP (1) EP3998126A4 (fr)
JP (1) JP6989060B2 (fr)
KR (1) KR102616194B1 (fr)
CN (1) CN114126782B (fr)
TW (1) TWI753486B (fr)
WO (1) WO2021006253A1 (fr)

Cited By (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
EP3981526A4 (fr) * 2019-07-11 2022-08-31 JFE Steel Corporation Procédé et dispositif de refroidissement secondaire pour brame coulée en continu
EP4357047A1 (fr) * 2022-10-18 2024-04-24 SMS Group GmbH Guidage de barre de support pour une installation de coulée continue et procédé de refroidissement d'une barre de coulée

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EP4357047A1 (fr) * 2022-10-18 2024-04-24 SMS Group GmbH Guidage de barre de support pour une installation de coulée continue et procédé de refroidissement d'une barre de coulée

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JP6989060B2 (ja) 2022-01-05
EP3998126A4 (fr) 2022-09-14
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CN114126782B (zh) 2023-07-04
CN114126782A (zh) 2022-03-01
TW202106411A (zh) 2021-02-16
KR102616194B1 (ko) 2023-12-19
JPWO2021006253A1 (ja) 2021-12-02
KR20220017493A (ko) 2022-02-11

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