WO2017115742A1

WO2017115742A1 - Rapid cooling quenching device and rapid cooling quenching method

Info

Publication number: WO2017115742A1
Application number: PCT/JP2016/088643
Authority: WO
Inventors: 宗司吉本; 広和杉原; 富士夫田中; 智弘橋向
Original assignee: Ｊｆｅスチール株式会社
Priority date: 2015-12-28
Filing date: 2016-12-26
Publication date: 2017-07-06

Abstract

The present invention addresses the problem of providing a rapid cooling quenching device and method for metal sheets, the device and method being capable of suppressing a reduction in the cooling speed of the metal sheets while limiting shape defects occurring in the metal sheets during rapid cooling quenching, in a continuous annealing facility for annealing while continuously passing metal sheets,. This rapid cooling quenching device for metal sheets immerses high-temperature metal sheets in a liquid to cool the metal sheets, and is characterized by being provided with: a water-bath that contains the liquid in which the metal sheets are immersed; a jetting device, at least a portion of which is provided in the liquid in the water-bath, and which is provided with a plurality of nozzles jetting the liquid onto the front surface and rear surface of the metal sheets; and a pair or a plurality of pairs of constraining rolls which constrain the metal sheets and are provided between an inlet side end section and an outlet side end section of the jetting device, wherein the nozzles closest to the constraining rolls in the jetting device are inclined from a horizontal plane toward the constraining rolls.

Description

Rapid quenching apparatus and quench quenching method

The present invention is a continuous annealing facility that performs annealing while continuously passing a metal plate, and quenching that can suppress a decrease in the cooling rate of the metal plate while suppressing a shape defect that occurs in the metal plate during quench quenching. The present invention relates to a quenching apparatus and a rapid quenching method.

In the production of metal plates such as steel plates, the materials are built in a continuous annealing facility by cooling the metal plates after heating and causing phase transformation. In recent years, in the automobile industry, demand for high-strength steel sheets with a reduced thickness has been increasing for the purpose of reducing the weight of the vehicle body and collision safety. A technology for rapidly cooling a steel sheet is important during the production of high tension steel. A water quenching method is known as one of the fastest cooling techniques for steel sheets. In the water quenching method, the steel sheet is quenched and quenched by immersing the heated steel sheet in water and simultaneously injecting cooling water onto the steel sheet with a quench nozzle provided in the water. At the time of quenching and quenching a steel plate, there is a problem that shape defects such as warpage and wave deformation occur in the steel plate. Conventionally, various methods have been proposed in order to prevent such shape defects during quench quenching of steel plates.

For example, in Patent Document 1, a bridle roll is used as a tension changing means that can change the tension of a steel sheet that is subjected to a quenching and quenching process in order to suppress the wavy deformation of a metal plate that occurs during quenching and quenching in a continuous annealing furnace. There has been proposed a method of providing a material before and after quenching and quenching. Patent Document 2 proposes a method of correcting a steel plate to be flat by applying tension over at least the entire width direction of the front and back surfaces of the steel plate during quenching.

However, since the method described in Patent Document 1 applies a large tension to a high-temperature steel sheet, the steel sheet may be broken. In addition, a large thermal crown is generated in the bridle roll before the quenching and quenching portion that comes into contact with the high-temperature steel plate, and the bridle roll and the steel plate come into non-uniform contact in the width direction. As a result, buckling and wrinkling occur in the steel plate, and there is a problem that the shape of the steel plate cannot be improved. Further, in the method described in Patent Document 2, the warpage amount is reduced to about several mm by setting the tension to 15 N / mm ² , but there is a possibility that the steel strip may be squeezed at such a high tension. .

The applicant has applied for a technique for solving these problems in Japanese Patent Application No. 2014-240836. A rapid quenching apparatus used in Japanese Patent Application No. 2014-240836 is shown in FIG. In FIG. 1, an ejection device 4 is provided in the water tank 1 to cool the metal plate 5 to the water temperature by spraying the cooling water. In the ejection device 4, the metal plate 5 is rapidly cooled by spraying the cooling water from the

nozzles

14 and 24 onto the metal plate 5, and the metal plate 5 is restrained by the restraining roll 7 disposed below the surface of the water. The deformation of the metal plate is suppressed.

JP 2011-184773 A JP-A-11-193418

When the quenching and quenching apparatus shown in FIG. 1 is used, it is possible to surely prevent deformation of the steel sheet during quenching and quenching, but when the metal plate passes through the ejection device 4, the cooling rate of the metal plate temporarily decreases. Thus, there is a problem that the characteristics of the metal plate deteriorate. Specifically, a metal plate having a desired tensile strength may not be obtained due to a decrease in the cooling rate of the metal plate.

Furthermore, in the rapid quenching apparatus of FIG. 1, since there is only one pair of restraining rolls, the shape failure of the steel sheet is suppressed to some extent, but the surface is not completely flat, and the steel sheet may have a warp of 5 mm or more. There is.

According to the study by the present inventors, it was found that the cooling rate of the metal plate is particularly likely to decrease in the vicinity of the restraining roll 7 in contact with the high-temperature metal plate. This will be described more specifically with reference to FIG. As shown by arrows in FIG. 2, the water ejected from the

nozzles

14 and 24 hits the front and back surfaces of the metal plate 5 inside the ejection device 4. At this time, water from the

nozzles

14 and 24 located above and below the restraining roll 7 hits the metal plate 5 and exhibits sufficient cooling ability. On the other hand, the water ejected from the

nozzles

14 and 24 located at a height overlapping with the restraint roll 7 is blocked by the restraint roll 7 and cannot reach the front and back surfaces of the metal plate 5. As a result, it has been found that the cooling rate of the metal plate tends to decrease in the vicinity of the restraining roll 7. Moreover, the temperature of the restraining roll 7 that is always in contact with the high-temperature metal plate 5 is likely to rise. Even when the temperature of the restraint roll 7 is increased, the cooling rate for the metal plate 5 in the vicinity of the restraint roll 7 is likely to decrease.

The present invention has been completed in view of the above-described problems, and it is possible to reduce the cooling rate of the metal plate in the vicinity of the restraining roll while maximally suppressing the shape defect that occurs in the metal plate during rapid quenching. It is an object to provide a quenching and quenching apparatus and a quenching and quenching method that can be suppressed.

Means for solving the above problems are as follows.
[1] A quenching and quenching apparatus for immersing and cooling a high-temperature metal plate in a liquid, wherein a water tank containing a liquid for immersing the metal plate, and at least a part of which is provided in the liquid in the water tank, An ejection device provided with a plurality of nozzles for injecting liquid on the front surface and the back surface, and a pair of restraining rolls provided between an entrance end and an exit end of the ejection device and restraining a metal plate The quenching and quenching apparatus according to claim 1, wherein the nozzle closest to the restraining roll is inclined from the horizontal plane toward the restraining roll.
[2] A quench quenching apparatus for immersing and cooling a high-temperature metal plate in a liquid, wherein a water tank containing a liquid for immersing the metal plate, and at least a part of which is provided in the liquid in the water tank, A jetting device having a plurality of nozzles for injecting liquid on the front surface and the back surface, a plurality of pairs of restraining rolls that are provided between an inlet side end portion and an outlet side end portion of the jetting device and restrain the metal plate; The quenching and quenching apparatus according to claim 1, wherein the nozzle closest to the restraining roll is inclined from the horizontal plane toward the restraining roll.
[3] The rapid quenching apparatus according to [1] or [2], wherein the nozzle closest to the restraining roll forms an angle of 20 ° to 60 ° with respect to the metal plate.
[4] A quench quenching method in which a high-temperature metal plate is cooled by immersing it in a liquid contained in a water tank, and the liquid is sprayed onto the front and back surfaces of the metal plate immersed in the liquid by a nozzle of the ejection device. The metal plate is restrained by a pair of restraining rolls provided between the entrance end and exit end of the ejection device, and obliquely toward the restraining roll from the nozzle closest to the restraining roll. A rapid quenching method characterized by ejecting a liquid.
[5] A quench quenching method in which a high-temperature metal plate is cooled by immersing it in a liquid contained in a water tank, and the liquid is sprayed onto the front and back surfaces of the metal plate immersed in the liquid by a nozzle of the ejection device. The metal plate is restrained by a plurality of pairs of restraining rolls provided between the inlet side end portion and the outlet side end portion of the ejection device, and obliquely toward the restraining roll from the nozzle closest to the restraining roll. A quenching and quenching method characterized by spouting a liquid on the surface.
[6] The quench quenching method according to [4] or [5], wherein the liquid is ejected from the nozzle closest to the restraining roll while forming an angle of 20 ° to 60 ° with respect to the metal plate. .

According to the present invention, it is possible to prevent the cooling rate of the metal plate from temporarily decreasing in the vicinity of the restraining roll during quenching and quenching.

FIG. 1 is an explanatory view showing a conventional quenching and quenching apparatus. FIG. 2 is an enlarged view showing the vicinity of the ejection device 4 of FIG. FIG. 3 is an explanatory view showing a rapid quenching apparatus according to the present invention. FIG. 4 is an enlarged view showing the vicinity of the ejection device 4 of FIG. FIG. 5 is an explanatory view showing another example of the rapid quenching apparatus according to the present invention. FIG. 6 is an explanatory view showing a rapid quenching apparatus according to the present invention. FIG. 7 is an enlarged view showing the vicinity of the ejection device 4 of FIG. FIG. 8 is an explanatory view showing a rapid quenching apparatus according to the present invention. FIG. 9 is an enlarged view showing the vicinity of the ejection device 4 of FIG. FIG. 10 is a graph showing the results of the example of the present invention. FIG. 11 is a graph showing the results of the comparative example. FIG. 12 is a graph showing the results of the present invention example and the comparative example. FIG. 13 is a graph showing the results of the inventive examples and the comparative examples. FIG. 14 is a schematic view of a steel plate viewed from the conveyance direction.

Hereinafter, embodiments of the present invention will be described in detail with reference to the accompanying drawings.

FIG. 3 is a diagram showing a quenching and quenching apparatus according to an embodiment of the present invention, and FIG. 4 is an enlarged view of the vicinity of the ejection device 4 of the quenching and quenching apparatus. The rapid quenching apparatus can be applied to a cooling facility provided on the exit side of the soaking zone of a continuous annealing furnace. FIG. 3 shows a pair of seal rolls 3 provided at the soaking exit of the continuous annealing furnace. The quenching and quenching apparatus includes a water tank 1 containing water 2 as a refrigerant (liquid) for cooling the metal plate 5, an ejection device 4 for cooling the metal plate 5 by spraying the water 2, and the metal plate 5. A restraining roll 7 that restrains and prevents deformation is provided. In addition, a sink roll 6 is provided on the exit side of the ejection device 4 to change the conveying direction (passing plate direction) of the metal plate 5 while immersing the metal plate 5 in water.

The ejection device 4 includes a plurality of

nozzles

14 and 24 that eject water and

nozzle units

34 and 44 that hold the

nozzles

14 and 24. A gap is provided between the pair of

nozzle units

34 and 44. When the metal plate 5 is passed through the gap, water is ejected from the

nozzles

14 and 24 toward the front and back surfaces of the metal plate 5. In the example of FIG. 3 (and FIG. 4), the left side of the metal plate 5 is the front surface, and the right side is the back surface. On the left side of the figure, a nozzle unit 34 is arranged so that the nozzle 14 faces the surface of the metal plate 5, and on the right side of the figure, a nozzle unit 44 is arranged so that the nozzle 24 faces the back surface of the metal plate 5. .

3 and 4, the

nozzle units

34 and 44 are each divided into two along the transport direction. An entrance nozzle unit 34a and an exit nozzle unit 34b are provided on the front side of the metal plate 5, and an entrance nozzle unit 44a and an exit nozzle unit 44b are provided on the back side. The restraint roll 7 is provided between the

inlet nozzle units

34a and 44a and the

outlet nozzle units

34b and 44b. Thereby, the restraining roll 7 includes an inlet side end portion (an inlet side end surface of the inlet

side nozzle units

34a and 44a in FIG. 3) and an outlet side end portion (the outlet side nozzle unit 34b in FIG. 3) of the ejection device. 44b on the outlet side end surface).

Entry nozzle units

34a and 44a are provided such that a part is immersed in the water and the remaining part comes out of the water. The metal plate 5 that has been passed through is inserted into the gaps inside the

inlet nozzle units

34a and 44a exposed on the water, then immersed in water, and water is ejected from the

nozzles

14 and 24. A plurality of

nozzles

14 and 24 are provided in the

inlet nozzle units

34a and 44a. Some nozzles (for example, the nozzle provided on the uppermost side of the inlet

side nozzle units

34a and 44a in FIG. 3) have nozzle openings located above the water surface, and at least some of the nozzle openings are submerged. It is in the state which is not immersed in. The nozzle whose opening is located above the water surface has been conventionally used so that water can be ejected obliquely downward in order to suppress the spout of water generated when the high-temperature metal plate 5 is introduced into the water ( For example, as shown in FIG.

The metal plate 5 is restrained by the restraining roll 7 after passing through the entry

side nozzle units

34a and 44a. The restraint roll 7 sandwiches the metal plate 5 from the front and back surfaces in water in order to prevent deformation that may occur when the metal plate 5 is rapidly cooled. The pair of restraining rolls 7 are preferably arranged with the central axis shifted in the conveying direction of the metal plate 5. By displacing the central axis, the restraining force of the metal plate 5 can be increased and the shape correction force can be increased. As an example, it is preferable to dispose the constraining roll 7 by shifting each central axis in the transport direction by 40 mm or more and 150 mm or less, and it is more preferable to dispose the restraining roll 7 by 80 mm or more and 100 mm or less.

Also, it is desirable to push the metal plate 5 by the restraining roll 7 and pass the metal plate 5 around the restraining roll 7. By pushing the metal plate 5, it is possible to increase the straightening force of the steel plate and to prevent the restraint roll 7 from idling. The pushing amount by one restraint roll 7 shall be 0 mm or more and 2.5 mm or less when the case where the metal plate 5 is linearly passed as shown in FIGS. 3 and 4 is set as a reference (0 mm). Is preferable, and it is more preferable to set it to 0.5 mm or more and 1.0 mm or less.

The metal plate 5 passes through the gap between the

outlet nozzle units

34b and 44b after passing through the restraining roll 7. Also at this time, water is ejected to the front and back surfaces of the metal plate 5 by the

nozzles

14 and 24 provided in the

outlet nozzle units

34b and 44b.

In the example of FIG. 3, the inlet

side nozzle units

34 a and 44 a and the outlet

side nozzle units

34 b and 44 b are provided so as to sandwich the restraint roll 7. Is not provided. In such an example, the nozzle located on the most outlet side of the

inlet nozzle units

34a and 44a (the third nozzle from the top in FIGS. 3 and 4) and the nozzle located on the most inlet side of the

outlet nozzle units

34b and 44b. The nozzle (the third nozzle from the bottom in FIG. 3 and FIG. 4) is the nozzle closest to the restraining roll 7 (hereinafter, may be referred to as the “nearest nozzle”).

The most recent nozzle is not horizontal as in the prior art, but is inclined so that the opening of the nozzle faces the restraint roll 7 from the horizontal plane. More specifically, the nearest nozzle located on the most outlet side of the entry

side nozzle units

34a and 44a in FIG. 4 is tilted downward and installed closest to the entry

side nozzle units

34b and 44b. The nozzle is mounted tilted upward. When the nearest nozzle is tilted in this way, the water ejected from the nearest nozzle reaches a position closer to the contact point between the restraining roll 7 and the metal plate 5 as compared with the conventional example in which the nearest nozzle is provided to be horizontal. Can be made. Thereby, it is possible to prevent a decrease in the cooling capacity for the metal plate 5 in the vicinity of the restraint roll 7 due to the fact that water ejected from the nozzle in the vicinity of the restraint roll 7 is difficult to contact the front and back surfaces of the metal plate 5. it can.

3 and 4, all the nozzles other than the nearest nozzle are also provided inclined in the same direction as the nearest nozzle, but the nozzles other than the nearest nozzle may be provided horizontally as in the past. However, from the viewpoint of making the contact position of water in the metal plate 5 as uniform as possible and eliminating uneven cooling in the longitudinal direction, it is preferable to incline all nozzles in each nozzle unit by the same angle in the same direction.

As shown in FIG. 4, as the inclination angle of the nearest nozzle, an acute angle a among the angles formed by the axial direction of the nearest nozzle (water ejection direction) and the metal plate can be set. In addition, although water is discharged from the nozzle with a certain spread, the direction of the central axis of the water discharged from the nozzle can be adopted as the water ejection direction. The angle a can be set according to the amount of water ejected from the nearest nozzle, the distance between the opening of the nearest nozzle and the restraining roll 7, the distance between the opening of the nearest nozzle and the front and back surfaces of the metal plate 5, and the like. . Preferable examples of the angle a include 20 ° or more and 60 ° or less. If the angle a is less than 20 °, the flow of water ejected from the nearest nozzle is hindered by the nearest restraining roll 7, and the water cannot reach the vicinity of the contact position between the restraining roll 7 and the metal plate 5. The effect which suppresses the cooling rate fall with respect to the metal plate 5 in 7 vicinity is not fully acquired. Further, when the angle a is more than 60 °, water is ejected in a form that is nearly perpendicular to the front and rear surfaces of the metal plate 5, and is sufficiently ejected to the front and rear surfaces of the metal plate 5 in the vicinity of the restraining roll 7. Water cannot be contacted, and the cooling capacity for the metal plate 5 is reduced. Further, it is more preferable that the angle a is 30 ° or more and 45 ° or less. When the nozzle is tilted, at least the tip of the nozzle may be tilted so that water can be ejected obliquely from the nozzle.

The rapid quenching apparatus according to the present invention may include a non-divided nozzle unit that is integrally formed along the conveying direction of the metal plate 5. An example using a non-divided nozzle unit will be described with reference to FIG.

In the example of FIG. 5, the left and

right nozzle units

34 and 44 are not divided along the transport direction, but are integrally formed. The restraining roll 7 is provided inside the gap between the

nozzle units

34 and 44. As described above, in an example in which the non-divided nozzle unit is employed, among the plurality of

nozzles

14 and 24 provided in the

nozzle units

34 and 44, there may be a nozzle whose opening portion overlaps with the height of the restraining roll 7. (In the example of FIG. 5, the fifth and sixth nozzles from the top of the nozzle unit 34 and the fourth and fifth nozzles from the top of the nozzle unit 44 correspond). In this case, the nozzle that overlaps the height of the restraining roll 7 and the height of the opening is excluded, and the nozzle closest to the restraining roll 7 among the other nozzles is set as the nearest nozzle. Further, the nozzles where the height of the restraining roll 7 and the height of the opening overlap may not be provided in the

nozzle units

34 and 44 from the beginning. In FIG. 5, the nearest nozzles are black.

Even in the example in which the non-divided nozzle unit is adopted, the cooling rate of the metal plate 5 in the vicinity of the restraining roll 7 can be similarly prevented by tilting the nearest nozzle toward the restraining roll 7.

It should be noted that the non-split type nozzle is used because the attachment and detachment and maintenance of the restraining roll 7 are facilitated, and the cooling capacity can be increased by reducing the distance between the openings of the

nozzles

14 and 24 and the metal plate 5. It is more preferable to employ a split nozzle unit (FIGS. 3 and 4) than a unit (FIG. 5).

Although not shown, each nozzle in the ejection device 4 is connected to a pipe provided with a pump on the way. By the pump, the water 2 in the water tank 1 is pumped up in the pipe and is pumped to the

nozzles

14 and 24, whereby high-pressure water is ejected from the openings of the

nozzles

14 and 24. Moreover, the water 2 in the water tank 1 is maintained so as to have a water temperature suitable for quenching. After a part of the water 2 in the aquarium 1 is sent to a cooling facility such as an external cooling tower and cooled, the cooled water 2 is returned to the aquarium 1 to prevent the water temperature in the aquarium 1 from rising. Is done. For example, the water temperature in the water tank 1 is preferably more than 0 ° C. and 50 ° C. or less, particularly preferably 10 ° C. or more and 40 ° C. or less.

In order to prevent the occurrence of roll wrinkles in the metal plate, it is preferable to rotate the restraining roll 7 in the circumferential direction by electric drive. Furthermore, in order to adjust the correction force of the metal plate 5, it is preferable that the restraint roll 7 can be opened and closed as necessary (the amount of pressing with respect to the metal plate 5 can be controlled).

The restraint roll 7 should just be formed with the material provided with the intensity | strength which can be equal to the load at the time of pinching of the metal plate 5, while being excellent in thermal conductivity. Examples of the material of the restraining roll 7 include SUS304, SUS310, and ceramic. Note that SUS304 and SUS310 can employ materials defined by JIS (Japanese Industrial Standards).

Next, an example using a plurality of pairs of restraining rolls 7 will be described with reference to FIGS. In the following, description of the same points as in the case of using the pair of restraining rolls 7 may be omitted.

6 and 7, the front and back surfaces of the metal plate 5 are restrained by two pairs of restraining rolls 7. In this case, similarly to the above, nozzles where the heights of the respective restraining rolls 7 overlap with the heights of the openings are excluded, and the nozzle closest to the restraining roll 7 among the other nozzles may be set as the nearest nozzle.

In Fig. 7, the nearest nozzles are black. Also in this example, the cooling rate of the metal plate 5 in the vicinity of the restraining roll 7 is prevented from being lowered by inclining the nearest nozzle toward the restraining roll. The nearest nozzle disposed between the restraining roll 7 and the restraining roll 7 may be inclined toward any restraining roll 7 adjacent to the nozzle. Furthermore, you may incline toward the adjacent restraining roll 7 by making the front-end | tip of a nozzle branch. Specifically, the nearest nozzle 14a, which is the seventh nozzle from the top on the front side in FIG. 7, and the nearest nozzle 24a, which is the ninth nozzle from the top on the back side, are jetted toward both the upper side and the lower side, respectively. It is configured to be possible.

8 and 9 show an example in which the front and back surfaces of the metal plate 5 are restrained by three pairs of restraining rolls 7. In this example as well, the nearest nozzle may be tilted toward the restraining roll 7 as described above.

Also in the example in which a plurality of pairs of restraining rolls are provided, for the same reason as in the example in which only one pair of restraining rolls is provided, a preferred example of the angle a for inclining the nearest nozzle can be 20 ° or more and 60 ° or less. 30 degrees or more and 45 degrees or less can be mentioned.

Also in the example in which a plurality of pairs of restraining rolls are provided, it is preferable to push the metal plate with the restraining rolls for the same reason as in the case of providing only one pair of restraining rolls. The pushing amount in each restraining roll is preferably 0 mm or more and 2.5 mm or less, and particularly preferably 0.5 mm or more and 1.0 mm or less.

In an example in which a plurality of pairs of restraining rolls are provided, it is preferable that the restraining rolls arranged on the front and back surfaces of the steel plate are displaced in the sheet passing direction and the restraining rolls are arranged in a staggered manner. Thereby, the restraining force of the metal plate 5 can be increased and the shape correction force can be further increased. In addition, it is preferable to set it as 40 mm or more and 150 mm or less, and the deviation | shift amount in the plate passing direction of the two central axes with the shortest distance among the restraining rolls 7 which opposes is set to 40 mm or more and 150 mm or less. Further preferred.

In the example in which a plurality of pairs of restraining rolls are provided, the shape correction force of the steel sheet during cooling can be further increased compared to the example in which only one pair of restraining rolls is provided. In particular, even when a high-strength steel sheet that is easily deformed is cooled, deformation such as warpage of the steel sheet during cooling can be further suppressed by providing a plurality of pairs of restraining rolls. On the other hand, if the number of restraining rolls is increased too much, there are problems such as equipment constraints and cooling capacity of the ejection device, so the number of restraining rolls may be appropriately determined in consideration of these problems.

The quench quenching apparatus and quench quenching method according to the present invention are particularly preferably applied to a method for producing a high-strength cold-rolled steel sheet (HITEN). More specifically, it is preferably applied to a method for producing a steel sheet having a tensile strength of 580 MPa or more. The upper limit of the tensile strength is not particularly limited, but may be 1600 MPa or less as an example. During the production of high tension, it is important to precisely control the structure by rapidly cooling the steel sheet. In the conventional quenching and quenching apparatus and quenching and quenching method, the cooling rate in the vicinity of the restraining roll 7 is reduced, so that a desired metal structure cannot be formed, and the strength of the high tension is lowered from a desired value. There is a problem. By applying the rapid quenching apparatus and the rapid quenching method according to the present invention to produce high tensile strength, it is possible to prevent a decrease in the cooling rate in the vicinity of the restraining roll 7 and to produce high strength tensile strength with a desired strength.

As specific examples of the composition of the high-strength cold-rolled steel sheet, by mass%, C is 0.04% to 0.25%, Si is 0.01% to 2.50%, Mn is 0.80% to 3 .70% or less, P is 0.001% or more and 0.090% or less, S is 0.0001% or more and 0.0050% or less, sol. Al is 0.005% or more and 0.065% or less, and if necessary, at least one of Cr, Mo, Nb, V, Ni, Cu, and Ti is 0.5% or less, and further if necessary. , B and Sb are each 0.01% or less, and the balance is Fe and inevitable impurities.

The embodiment of the present invention is not limited to an example in which a steel plate is cooled with water, but can be applied to cooling of a metal plate other than a steel plate in general, and also for quenching and quenching using a coolant other than water. Can be applied.

Hereinafter, the present invention will be described more specifically with reference to examples.
(Invention Example 1)
Using the rapid quenching apparatus shown in FIGS. 3 and 4, a high-tensile cold-rolled steel sheet having a sheet thickness of 1.0 mm, a sheet width of 1000 mm, and a tensile strength of 580 to 1470 MPa is manufactured at a sheeting speed of 1.0 m / s. did. In addition, all the angles a which incline the

nozzles

14 and 24 in the ejection apparatus 4 were 30 degrees. Here, the central axis of the restraint roll was shifted by 80 mm in the sheet passing direction, and the pushing amount of the restraint roll 7 into the metal plate 5 was all 0.5 mm.

Also, the temperature of the steel sheet in the plate was measured with a rapid quenching apparatus. Specifically, the temperature of the measurement area of the steel sheet was measured over time using a thermocouple thermometer. The cooling start temperature of the steel sheet (temperature immediately before entering the ejection device 4) was 740 ° C., and the cooling end temperature (temperature immediately after exiting the water tank 1) was 50 ° C. The cooling rate of the steel sheet was calculated from the relationship between the elapsed time after the start of cooling and the temperature of the steel sheet. The results are shown in FIG.

Also, the amount of warpage of the steel sheet was measured after passing. Specifically, it demonstrates using FIG. 14 which looked at the steel plate directly from the conveyance direction. When warpage occurs in the steel plate, a high portion and a low portion are formed in the width direction of the steel plate. In the steel plate after passing, the difference in height between the highest part and the lowest part was measured as the amount of warpage.

(Comparative Example 1)
Experiments were performed in the same manner as Example 1 except that the quenching and quenching apparatus shown in FIGS. 1 and 2 was used. Note that the inclination angle of the latest nozzle was 90 °. The results are shown in FIG.

In FIG. 10 (example of the present invention), the cooling rate of the steel sheet did not decrease with time and was almost constant. On the other hand, in FIG. 11 (comparative example), the cooling rate decreases by about 40% (1500 ° C./s→900° C./s) when the elapsed time is between 0.2 (s) and 0.4 (s). ing. During the time when the cooling rate was reduced, the steel plate passed near the restraining roll 7. From the above, it has been shown that the use of the quenching and quenching apparatus according to the present invention can suppress a decrease in the cooling rate of the metal plate in the vicinity of the restraining roll.

Also, the tensile strength of the steel sheet manufactured according to Invention Example 1 was approximately 1470 MPa, whereas the tensile strength of the steel sheet manufactured according to Comparative Example 1 was approximately 1400 MPa, and a decrease in tensile strength was observed. By applying this invention, the characteristic fall of the steel plate accompanying the fall of the cooling rate in the restraint roll vicinity was able to be prevented. The results regarding the warpage amount of the steel sheet will be described later.

(Invention Example 2)
An experiment similar to Example 1 of the present invention was performed by setting the angle a from 10 ° to 90 ° every 10 °. The example in which the angle a is 90 ° does not relate to the present invention but belongs to the comparative example. FIG. 12 shows a plot of the rate of decrease in the cooling rate of the steel sheet when passing through the vicinity of the restraining roll when the experiment was performed at each angle a.

As shown in FIG. 12, the cooling rate decreased by 40% in the case where a is 90 ° (comparative example). On the other hand, in each of the examples in which a was 10 ° to 80 ° (example of the present invention), the rate of decrease in the cooling rate could be suppressed to less than 30%. Particularly, in the case where a is 20 ° or more and 60 ° or less, the cooling rate of the steel sheet itself can be prevented (the reduction rate is 0%), which is particularly suitable. .

(Invention Example 3)
Using the rapid quenching apparatus shown in FIGS. 6 and 7, the operation was performed under the same conditions as in Example 1 of the present invention. The central axes of the constraining rolls facing each other are all shifted by 80 mm in the plate passing direction, and the pushing amount of the constraining roll 7 into the metal plate 5 is 0.5 mm.

(Invention Example 4)
Using the rapid quenching apparatus shown in FIGS. 8 and 9, the operation was performed under the same conditions as in Example 1 of the present invention. The central axes of the constraining rolls facing each other are all shifted by 80 mm in the plate passing direction, and the pushing amount of the constraining roll 7 into the metal plate 5 is 0.5 mm.
<Evaluation of cooling rate>
The measurement results of the cooling rate of the steel sheet in Invention Example 3 and Invention Example 4 were as shown in FIG. From these results, it was shown that even when a plurality of pairs of restraining rolls are used, it is possible to suppress a decrease in the cooling rate of the metal plate in the vicinity of the restraining rolls.
<Evaluation of warpage amount>
FIG. 13 shows the results of warpage amounts measured for three types of steel sheets in Invention Examples 1 and 3 to 4 and Comparative Example 1. The three types of steel plates are steel plates with a tensile strength of 580 MPa class, steel plates with a 1180 MPa class, and steel sheets with a 1470 MPa class. In addition, the amount of warpage of the steel sheet was the same in both inventive example 1 and comparative example 1. As shown in FIG. 13, even if it was a high-strength steel plate, the curvature amount of the steel plate was able to be suppressed by increasing the number of restraining rolls. Therefore, it was confirmed that the deformation of the steel sheet at the time of quenching and quenching can be further prevented by increasing the number of restraining rolls.

DESCRIPTION OF SYMBOLS 1 Water tank 2 Water 3 Seal roll 4 Jetting device 5 Metal plate 6 Sink roll 7, 17 Restraint roll 11

Quenching quenching device

14, 24

Nozzle

14a,

24a Nearest nozzle

34, 44

Nozzle unit

34a, 44b

Inlet nozzle unit

34b, 44b Outlet nozzle unit

Claims

A quench quenching device that cools a hot metal plate by immersing it in a liquid,
A water tank containing a liquid into which the metal plate is immersed;
An ejection device provided with a plurality of nozzles, at least a part of which is provided in the liquid of the water tank, and ejects the liquid to the front and back surfaces of the metal plate;
A pair of restraining rolls provided between the entry end and the exit end of the ejection device and restraining the metal plate;
The quenching and quenching apparatus according to claim 1, wherein the nozzle closest to the restraining roll is inclined from the horizontal plane toward the restraining roll.
A quench quenching device that cools a hot metal plate by immersing it in a liquid,
A water tank containing a liquid into which the metal plate is immersed;
An ejection device provided with a plurality of nozzles, at least a part of which is provided in the liquid of the water tank, and ejects the liquid to the front and back surfaces of the metal plate;
A plurality of pairs of restraining rolls that are provided between the inlet end and the outlet end of the ejection device and restrain the metal plate;
The quenching and quenching apparatus according to claim 1, wherein the nozzle closest to the restraining roll is inclined from the horizontal plane toward the restraining roll.
The rapid quenching apparatus according to claim 1 or 2, wherein the nozzle closest to the restraining roll forms an angle of 20 ° to 60 ° with respect to the metal plate.
A quench quenching method in which a high temperature metal plate is immersed in a liquid contained in a water bath and cooled,
While spraying the liquid on the front and back of the metal plate immersed in the liquid by the nozzle of the ejection device,
Restrain the metal plate by a pair of restraining rolls provided between the inlet end and the outlet end of the ejection device,
A rapid quenching method characterized in that liquid is ejected obliquely from the nozzle closest to the restraining roll toward the restraining roll.
A quench quenching method in which a high temperature metal plate is immersed in a liquid contained in a water bath and cooled,
While spraying the liquid on the front and back of the metal plate immersed in the liquid by the nozzle of the ejection device,
The metal plate is restrained by a plurality of pairs of restraining rolls provided between the inlet side end and the outlet side end of the ejection device,
A rapid quenching method characterized in that liquid is ejected obliquely from the nozzle closest to the restraining roll toward the restraining roll.
The rapid quenching method according to claim 4 or 5, wherein the liquid is ejected from the nozzle closest to the restraining roll while forming an angle of 20 ° to 60 ° with respect to the metal plate.