WO2020085353A1

WO2020085353A1 - Quenching device, quenching method, and steel sheet production method

Info

Publication number: WO2020085353A1
Application number: PCT/JP2019/041434
Authority: WO
Inventors: 宗司吉本; 智弘橋向; 宗佑鈴木
Original assignee: Ｊｆｅスチール株式会社
Priority date: 2018-10-25
Filing date: 2019-10-23
Publication date: 2020-04-30
Also published as: JPWO2020085353A1; CN112888797A; JP6879429B2

Abstract

Provided are a quenching device, a quenching method, and steel sheet production method, whereby shape defects in metal plates during quenching can be suppressed, reduction in metal plate cooling speed can be suppressed, and lack of uniformity of cooling speed in the plate width direction of the metal plates can be prevented. This quenching device immerses and cools a high-temperature metal plate in liquid and comprises: a tank housing the liquid in which the metal plate is immersed; a jetting device having at least part thereof provided inside the liquid in the tank and comprising a plurality of nozzles that jet the liquid on to the metal plate; and a restraining roll provided between an entry side end section and an exit side end section of the jetting device and pinching the metal plate from both sides. The jetting device is characterized by: at least a nozzle adjacent to the restraining roll being inclined from the horizontal, towards the restraining roll; the opening of the nozzle adjacent to the restraining roll being slit-shaped; and the width of the opening reducing from the center of the opening in the longitudinal direction to the end in the longitudinal direction.

Description

Quenching apparatus, quenching method, and steel sheet manufacturing method

The present invention relates to a quenching apparatus and a quenching method in a continuous annealing facility that performs annealing while continuously passing a metal plate, and a method for manufacturing a steel sheet.

In the production of metal sheets such as steel sheets, in a continuous annealing equipment, the metal sheet is heated and then cooled to undergo phase transformation, etc. to build in the material. In recent years, in the automobile industry, there is an increasing demand for thin high-strength steel sheets (high tensile strength steel sheets) for the purpose of achieving both weight reduction of vehicle bodies and collision safety. When manufacturing high-tensile steel, technology for rapidly cooling the steel sheet is important. A water quenching method is known as one of the technologies with the fastest cooling rate of a steel sheet. In the water quenching method, the steel sheet is quenched by immersing the heated steel sheet in water and at the same time spraying cooling water on the steel sheet by a quench nozzle provided in the water. When quenching a steel sheet, there is a problem in that the steel sheet suffers from shape defects such as warpage and wavy deformation. In order to prevent such a defective shape at the time of quenching a steel sheet, various methods have been conventionally proposed.

For example, in Patent Document 1, in order to suppress wavy deformation of a metal plate that occurs during quenching in a continuous annealing furnace, a method is proposed in which a bridle roll is provided before and after the quenching part as a tension changing means of the steel plate subjected to the quenching process. Has been done. Further, Patent Document 2 proposes a method of straightening a steel sheet by applying tension to at least the entire width direction of the front and back surfaces of the steel sheet during quenching. Further, Patent Document 3 proposes a method for preventing deformation of a steel plate by restraining a metal plate being quenched by a pair of restraining rolls.

However, the method described in Patent Document 1 applies a large amount of tension to a high temperature steel plate, so that the steel plate may be broken. In addition, a large thermal crown is generated on the bridle roll before the quenching part, which comes into contact with the high temperature steel plate, and the bridle roll and the steel plate are unevenly contacted in the width direction. As a result, buckling or flaws occur in the steel sheet, and there is a problem that the shape of the steel sheet cannot be improved.
Further, in the method described in Patent Document 2, the amount of warp is reduced to about several mm by setting the tension to 15 N / mm ² , but such high tension may cause drawing in the steel strip. .
Further, in the method described in Patent Document 3, the deformation of the steel plate during quenching can be prevented, but when the metal plate passes through the constraining roll, the cooling rate of the metal plate is temporarily reduced, so that the metal plate However, there is a problem in that 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.
The applicant discloses a technique for solving these problems in Patent Document 4. Patent Document 4 proposes a method of ejecting a liquid obliquely toward the constraining roll from the nozzle closest to the constraining roll while constraining the metal plate being quenched by a pair or a plurality of constraining rolls. .

JP, 2011-184773, A Japanese Patent Laid-Open No. 11-193418 Japanese Patent No. 6094722 JP, 2017-119912, A

However, in the method described in Patent Document 4, it is possible to suppress the deformation of the steel plate during quenching and suppress the decrease in the cooling rate of the metal plate near the restraint roll. There is a problem that the cooling rate becomes uneven. Specifically, the cooling rate of the edge part is higher than that of the central part of the metal plate, and the tensile strength of the edge part is higher than that of the central part of the metal plate due to the uneven cooling rate. is there.

The inventors of the present invention have earnestly studied to solve such a problem, and have obtained the following findings. Since the constraining roll and the metal plate are in contact with each other across the entire width of the metal plate, the escape area for the water ejected from the nozzle adjacent to the constraining roll is only in the width direction, and the central part of the metal plate The colliding water will flow laterally. Therefore, the cooling rate on the metal plate tends to be higher in the edge portion than in the central portion of the metal plate.

The present invention has been completed based on the above findings. That is, a quenching device and a quenching device capable of preventing non-uniformity of the cooling rate of the metal plate in the plate width direction while suppressing a decrease in the cooling rate of the metal plate while suppressing a shape defect that occurs in the metal plate during quenching. It is an object to provide a method and a method for manufacturing a steel sheet.

Means for solving the above problems are as follows.
[1] A tank containing a liquid in which a high-temperature metal plate is immersed,
At least a part is provided in the liquid of the tank, a jetting device including a plurality of nozzles for jetting the liquid on both surfaces of the metal plate,
A restraint roll that is provided between an inlet side end and an outlet side end of the ejection device and that holds the metal plate from both sides,
In the ejection device, at least the nozzle adjacent to the restraint roll is inclined from the direction perpendicular to the metal plate toward the restraint roll,
The opening of the nozzle adjacent to the constraining roll has a slit-like shape,
A quenching device, wherein the opening width of the opening is reduced from the central portion in the longitudinal direction of the opening to the end portion in the longitudinal direction.
[2] The quenching device according to [1], wherein the opening width of the opening decreases discontinuously from the central portion in the longitudinal direction of the opening to the end portion in the longitudinal direction.
[3] The quenching apparatus according to [1], wherein the opening width of the opening is continuously reduced from the central portion in the longitudinal direction of the opening to the end portion in the longitudinal direction.
[4] The quenching device according to any one of [1] to [3], which has a region having a uniform opening width in a central portion in the longitudinal direction of the opening.
[5] A quenching method in which quenching is performed using the quenching device according to any one of [1] to [4].
[6] A method for manufacturing a steel sheet, which uses the quenching method described in [5] above when manufacturing a steel sheet.
[7] The opening width of the opening is 2 mm or more and 5 mm or less at the central portion in the longitudinal direction of the opening, and is more than 0 mm and 3 mm or less at the end portions in the longitudinal direction of the opening, and the opening at the central portion in the longitudinal direction. The quenching device according to any one of [1] to [3], wherein the opening width of the longitudinal end portion is smaller than the width.

According to the present invention, it is possible to prevent the non-uniformity of the cooling rate of the metal plate in the plate width direction while suppressing the shape defect that occurs in the metal plate during quenching and suppressing the decrease of the cooling rate of the metal plate.

FIG. 1 is an explanatory diagram showing a basic configuration of a quenching apparatus according to an embodiment of the present invention. FIG. 2 is an enlarged view showing the vicinity of the ejection device of FIG. FIG. 3 is an enlarged view of an example of the openings of the adjacent nozzles in the embodiment of the present invention. FIG. 4 is an enlarged view of another example of the openings of the adjacent nozzles in the embodiment of the present invention. FIG. 5 is an enlarged view of an opening of a conventional adjacent nozzle. FIG. 6 is a graph showing the results of Example 1 of the present invention. FIG. 7 is a graph showing the results of Example 2 of the present invention. FIG. 8 is a graph showing the results of Example 3 of the present invention. FIG. 9 is a graph showing the results of Comparative Example 1. FIG. 10 is a graph showing the results of Comparative Example 2. FIG. 11 is a graph showing the results of Inventive Examples 1, 2, and 3 and Comparative Examples 1 and 2. FIG. 12 is a schematic view of the steel sheet viewed from the conveyance direction.

An embodiment of the present invention will be specifically described below with reference to the drawings.

FIG. 1 is a diagram showing a basic configuration of a quenching apparatus according to an embodiment of the present invention. FIG. 2 is an enlarged view of the vicinity of the ejection device 4 of the quenching device shown in FIG. The quenching device can be applied to a cooling facility provided on the outflow side of the soaking zone of a continuous annealing furnace. FIG. 1 shows a pair of seal rolls 3 provided at the soaking zone outlet of the continuous annealing furnace. The quenching apparatus includes a water tank 1 containing water 2 which is a coolant (liquid) for cooling the metal plate 5, a jetting device 4 for spraying the water 2 on both surfaces of the metal plate 5 for cooling, and a metal plate 5 And a restraining roll 7 for restraining the deformation and preventing the deformation. At least a part of the ejection device 4 is provided in the liquid (in the water 2) of the tank 1. A sink roll 6 is provided on the outlet side of the ejection device 4 to change the transport direction (passing 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 jetted from the

nozzles

14 and 24 toward the front and back surfaces of the metal plate 5. In the example of FIGS. 1 and 2, 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, the nozzle unit 34 is arranged so that the nozzle 14 faces the front surface of the metal plate 5, and on the right side of the figure, the nozzle unit 44 faces so that the nozzle 24 faces the back surface of the metal plate 5. Will be placed.

In the example of FIGS. 1 and 2, the

nozzle units

34 and 44 are each divided into two along the carrying direction. An inlet side nozzle unit 34a and an outlet side nozzle unit 34b are provided on the front surface side of the metal plate 5, and an inlet side nozzle unit 44a and an outlet side nozzle unit 44b are provided on the back surface 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 restraint roll 7 is provided between the inlet side end portion (the inlet side end surface of the inlet

side nozzle units

34a, 44a) and the outlet side end portion (the outlet side end surface of the outlet

side nozzle units

34b, 44b) of the ejection device. Will be provided.

The

inlet nozzle units

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

inlet nozzle units

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

nozzles

14 and 24. The

inlet nozzle units

34a, 44a are provided with a plurality of

nozzles

14, 24. Some nozzles (for example, the nozzles provided at the top of the inlet-

side nozzle units

34a and 44a in FIG. 1) have an opening of the nozzle located above the water surface, and at least a part of the opening of the nozzle is underwater. Not soaked in. The nozzle whose opening is located above the water surface suppresses the water from being blown up when the high-temperature metal plate 5 is introduced into the water. It is installed diagonally.

The metal plate 5 is constrained by the constraining roll 7 after passing through the

inlet nozzle units

34a, 44a. The restraint roll 7 sandwiches the metal plate 5 from both sides (front and back surfaces) in water in order to prevent deformation that may occur when the metal plate 5 is rapidly cooled. It is preferable that the pair of restraining rolls 7 are arranged with their central axes displaced in the transport direction of the metal plate 5. By arranging the central axes so as to be displaced, the restraining force of the metal plate 5 can be increased and the shape correcting force can be increased. As an example, it is preferable to dispose the constraining rolls 7 by displacing the respective central axes in the transport direction by 40 mm or more and 150 mm or less, and it is more preferable to dispose the constraining rolls 7 by 80 mm or more and 100 mm or less.

Also, it is desirable to push the metal plate 5 with the restraint roll 7 and pass the metal plate 5 around the restraint roll 7 so as to wind it. By pushing in the metal plate 5, the correction force can be increased. The pushing amount by one restraint roll 7 is 0 mm or more and 2.5 mm or less in the horizontal direction when the reference (0 mm) is the case where the metal plate 5 is linearly threaded as shown in FIGS. 1 and 2. It is preferable that More preferably, it is 0.5 mm or more and 1.0 mm or less.

After passing through the constraining roll 7, the metal plate 5 passes through the gap between the

outlet nozzle units

34b and 44b. Also at this time, water is jetted 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. 1, the inlet-

side nozzle units

34a and 44a and the outlet-

side nozzle units

34b and 44b are provided so as to sandwich the constraining roll 7 from above and below, and the height of the constraining roll 7 and the nozzle unit and the nozzles Is not provided. In such an example, the

nozzles

14a and 24a located on the most outlet side of the inlet

side nozzle units

34a and 44a and the

nozzles

14b and 24b located on the most inlet side of the outlet

side nozzle units

34b and 44b are attached to the restraining roll 7. It becomes an adjacent nozzle. The above adjacent nozzles may be referred to as "adjacent nozzles" hereinafter.

The adjacent nozzles are not horizontal but are installed so as to be inclined so that the nozzle openings face from the horizontal plane toward the constraining roll 7. That is, the adjacent nozzles are inclined from the direction perpendicular to the metal plate 5 toward the restraining roll 7. More specifically, the

adjacent nozzles

14a and 24a in FIG. 2 are attached while being inclined downward, and the

adjacent nozzles

14b and 24b are attached while being inclined upward. Inclining the adjacent nozzles in this way allows the water ejected from the adjacent nozzles to reach a position closer to the contact point between the constraining roll 7 and the metal plate 5, as compared with the case where the adjacent nozzles are provided horizontally. You can As a result, it is possible to prevent the cooling ability of the metal plate 5 near the constraining roll 7 from being lowered due to the fact that the water ejected from the nozzle near the constraining roll 7 does not easily contact the front and back surfaces of the metal plate 5. it can.

In the example of FIGS. 1 and 2, all the nozzles other than the adjacent nozzles are also tilted in the same direction as the adjacent nozzles, but the nozzles other than the adjacent nozzles may be horizontally provided as before. However, from the viewpoint of making the contact position of water on the metal plate 5 as uniform as possible, it is preferable to incline all the nozzles in each nozzle unit in the same direction by the same angle.

As shown in FIG. 2, the inclination angle of the adjacent nozzle may be set to an acute angle θ among the angles formed by the axial direction of the adjacent nozzle (liquid ejection direction (water ejection direction)) and the metal plate. it can. 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 jetting direction of the water. The angle θ can be set according to the amount of water jetted from the adjacent nozzle, the distance between the opening of the adjacent nozzle and the restraint roll 7, the distance between the opening of the adjacent nozzle and the front and back surfaces of the metal plate 5, and the like. . A preferable example of the angle θ is 20 ° or more and 60 ° or less. If the angle θ is 20 ° or more and 60 ° or less, the flow of water ejected from the adjacent nozzle reaches the vicinity of the contact position between the restraint roll 7 and the metal plate 5, and the metal plate 5 near the restraint roll 7 is reached. It is possible to sufficiently obtain the effect of suppressing the decrease in the cooling rate.
Further, it is more preferable that the angle θ is 30 ° or more and 45 ° or less. When inclining the nozzle, at least the tip of the nozzle may be inclined so that water can be jetted obliquely from the nozzle.

Further, the quenching device according to the present invention may include a non-divided nozzle unit integrally formed along the transport direction of the metal plate 5.
Although not shown, each nozzle in the ejection device 4 is connected to a pipe provided with a pump in the middle. By the pump, the water 2 in the water tank 1 is pumped up in the pipe and pressure-fed to the

nozzles

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

nozzles

14 and 24.

Also, the water 2 in the water tank 1 is maintained at a water temperature suitable for quenching. Part of the water 2 in the water tank 1 is sent to a cooling facility such as an external cooling tower to be cooled, and then the cooled water 2 is returned to the water tank 1 to prevent an increase in the water temperature in the water tank 1. To be done. For example, the water temperature in the water tank 1 is preferably more than 0 ° C and 50 ° C or less, and particularly preferably 10 ° C or more and 40 ° C or less.

Then, the quenching apparatus according to the embodiment of the present invention includes the adjacent nozzle having an opening (ejection hole) having a shape different from the opening (ejection hole) of the conventional adjacent nozzle. This will be described below with reference to FIGS. 3, 4, and 5. The opening width of the opening is the opening amount of the metal plate 5 in the sheet passing direction (vertical direction in each drawing), and the longitudinal direction of the opening is the plate width direction of the metal plate 5 (left and right in each drawing). Direction).

First, FIG. 5 is an enlarged view of the openings 14a (14aX), 24a (24aX), 14b (14bX), and 24b (24bX) of the conventional adjacent nozzles. Since the opening widths of the openings 14aX, 24aX, 14bX, 24bX of the adjacent nozzles are the same in the longitudinal direction of the openings, the water ejected from the adjacent nozzles has the same flow rate in the plate width direction of the metal plate 5. Further, the escape area of the water ejected from the adjacent nozzle of the restraint roll 5 is only in the plate width direction of the metal plate 5, so that the water that collides with the central portion of the metal plate 5 flows laterally. From the above two effects, the cooling rate on the metal plate 5 tends to be higher in the edge portion than in the central portion of the metal plate 5.

On the other hand, FIG. 3 is an enlarged view of the openings 14a (14aA), 24a (24aA), 14b (14bA), 24b (24bA) of the adjacent nozzles in the embodiment of the present invention.
Further, FIG. 4 is an enlarged view of the other openings 14aB, 24aB, 14bB, 24bB of the adjacent nozzles in the embodiment of the present invention.

In the example of FIGS. 3 and 4, the opening is slit-shaped, and the opening width at the longitudinal end is smaller than the opening width at the central portion in the longitudinal direction of the opening. Specifically, the openings 14aA, 24aA, 14bA, and 24bA of FIG. 3 have a wide and uniform region at the central portion in the longitudinal direction and a narrow and uniform region at the end portions in the longitudinal direction. That is, the opening width decreases discontinuously (stepwise) from the central portion in the longitudinal direction to the end portion in the longitudinal direction.

On the other hand, the openings 14aB, 24aB, 14bB, 24bB of FIG. 4 have a wide and uniform area in the central portion in the longitudinal direction, and the opening width continuously decreases from there to the end portion in the longitudinal direction. . As described above, in any of the openings, the opening width of the opening of the adjacent nozzle decreases from the central portion in the longitudinal direction of the opening to the end portion in the longitudinal direction.
Therefore, the amount of water ejected from the adjacent nozzles is smaller in the edge portion than in the central portion in the plate width direction of the metal plate 5. Further, the escape area for the water ejected from the adjacent nozzle of the restraint roll 7 is only in the plate width direction of the metal plate 5, so that the water that collides with the central portion of the metal plate 5 will flow laterally. From the above two effects, the cooling rate on the metal plate 5 is uniform in the plate width direction without any difference between the central part and the edge part of the metal plate 5.

The shape of the longitudinal ends of the openings of the adjacent nozzles may be parallel to the plate width direction as shown in FIG. 3 or may be oblique to the plate width direction as shown in FIG. However, the opening width at the longitudinal end must be smaller than the opening width at the central portion in the longitudinal direction.

As a specific value, the opening width of the opening of the adjacent nozzle is preferably 2 mm or more and 5 mm or less, more preferably 2 mm or more and 4 mm or less, and even more preferably 2 mm or more and 3 mm or less. Further, the opening width of the longitudinal end portion is preferably more than 0 mm and 3 mm or less, more preferably 1 mm or more and 3 mm or less, and further preferably 1 mm or more and 2 mm or less.

The length of the opening of the adjacent nozzle in the longitudinal direction is, as a specific value, preferably 600 mm or more and 1200 mm or less, more preferably 800 mm or more and 1000 mm or less, and 850 mm or more and 950 mm or less in the length of the central portion in the longitudinal direction. More preferable. The total length in the longitudinal direction is preferably 1400 mm or more and 2000 mm or less, more preferably 1500 mm or more and 1900 mm or less, and further preferably 1600 mm or more and 1800 mm or less.

Then, in order to suppress the slip between the metal plate and the roll, it is preferable to use the restraint roll 7 as a drive roll. Further, 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 (the amount of pushing into the metal plate 5 can be controlled) as necessary.

The restraint roll 7 may be formed of a material having excellent thermal conductivity and strength enough to withstand the load when the metal plate 5 is pinched. Examples of the material of the constraining roll 7 include SUS304, SUS310, and ceramics.

The quenching apparatus and the quenching method using the quenching apparatus according to the embodiment of the present invention as described above can be applied to the production of a steel sheet, and particularly preferably applied to the method for producing a high-strength cold-rolled steel sheet (high tensile strength steel sheet). . More specifically, it is preferably applied to a method for manufacturing 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 tensile strength steel, it is important to control the structure precisely by rapidly cooling the steel sheet. By applying this embodiment, it is possible to prevent the non-uniformity of the cooling rate in the plate width direction while reliably suppressing the shape defect that occurs at the time of quenching and preventing the cooling rate from decreasing in the vicinity of the constraining roll 7. It is possible to manufacture high tensile strength steel having a desired strength.

As a specific example of the composition of the high-strength cold-rolled steel sheet, C is 0.04% or more and 0.25% or less, Si is 0.01% or more and 2.50% or less, and Mn is 0.80% or more and 3% by mass. .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 kind of Cr, Mo, Nb, V, Ni, Cu, and Ti is 0.5% or less, and 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 of rapidly cooling a steel sheet, but can be applied to the rapid cooling of all metal sheets other than the steel sheet, and is also applied to quenching using a liquid other than water. can do.

The present invention will be described in more detail below using examples.

(Invention Example 1)
When manufacturing a high-strength cold-rolled steel sheet having a tensile strength of 1470 MPa, quenching is performed by using the quenching apparatus shown in FIGS. 1 and 2 and the adjacent nozzle having the openings 14aA, 24aA, 14bA, 24bA shown in FIG. went. The plate thickness was 1.0 mm, the plate width was 1000 mm, and the plate passing speed was 1.0 m / s. In addition, the angles θ at which the

nozzles

14 and 24 are inclined in the ejection device 4 are all 30 °. Here, the central axis of the constraining roll 7 was arranged so as to be displaced by 80 mm in the sheet passing direction, and the pushing amount of the constraining roll 7 into the metal plate 5 was all 0.5 mm. The opening widths of the openings 14aA, 24aA, 14bA, and 24bA of the adjacent nozzles were 2 mm at the center in the longitudinal direction and 1 mm at the ends in the longitudinal direction.

Also, the temperature of the steel plate being passed through the quenching device was measured. Specifically, the temperature of the measured region of the steel sheet was measured with time using a thermocouple-type thermometer. The cooling start temperature of the steel sheet (the temperature immediately before entering the jetting device 4) was 740 ° C, and the cooling end temperature (the temperature immediately after leaving the water tank 1) was 30 ° C. From the relationship between the elapsed time after the start of cooling and the temperature of the steel sheet, the cooling rate distribution in the sheet width direction of the steel sheet at the moment when the steel sheet was in contact with the restraint roll 7A was calculated. Results are shown in FIG.

Also, the amount of warp of the steel plate was measured after passing the plate. Specifically, a description will be given with reference to FIG. 12 in which the steel sheet is viewed from the conveying direction. When the steel plate warps, a high-height portion and a low-height portion are formed in the width direction of the steel sheet. In the steel sheet after passing, the difference in height between the highest portion and the lowest portion was measured as the amount of warpage.

(Invention Example 2)
An experiment was performed in the same manner as in Example 1 of the present invention, except that the opening widths of the openings 14aA, 24aA, 14bA, and 24bA of the adjacent nozzles were 5 mm at the central portion in the longitudinal direction and 3 mm at the end portions in the longitudinal direction. The results are shown in Fig. 7.

(Invention Example 3)
An experiment was conducted in the same manner as in Example 1 of the present invention, except that the opening widths of the openings 14aA, 24aA, 14bA, and 24bA of the adjacent nozzles were 7 mm at the central portion in the longitudinal direction and 5 mm at the end portions in the longitudinal direction. The results are shown in Fig. 8.

(Comparative Example 1)
An experiment was conducted in the same manner as Example 1 of the present invention, except that the quenching device described in Patent Document 4 and the adjacent nozzles having the openings 14aX, 24aX, 14bX, 24bX shown in FIG. 5 were used. The opening width of the openings 14aX, 24aX, 14bX, 24bX of the adjacent nozzles was set to a constant 2 mm in the longitudinal direction. The results are shown in Fig. 9.

(Comparative example 2)
An experiment was conducted in the same manner as Example 1 of the present invention, except that the quenching device described in Patent Document 3 and the adjacent nozzle having the openings 14aX, 24aX, 14bX, 24bX shown in FIG. 5 were used. The opening width of the openings 14aX, 24aX, 14bX, 24bX of the adjacent nozzles was set to a constant 2 mm in the longitudinal direction. The inclination angle of the adjacent nozzle was 90 °. The results are shown in Fig. 10.

<Evaluation of cooling rate>
In FIGS. 6, 7, and 8 (Examples 1, 2, and 3 of the present invention), the cooling rate distribution in the plate width direction of the steel plate is substantially constant regardless of the plate width position, and the steel plate is cooled substantially uniformly. The cooling rate was 1500 ° C / s.
On the other hand, in FIG. 9 (Comparative Example 1), the cooling rate is higher in the edge portion than in the central portion, and the cooling is uneven. The cooling rate was 1500 ° C./s at the center and 2000 ° C./s at the edges.
Similarly, in FIG. 10 (Comparative Example 2), the cooling rate is higher in the edge portion than in the central portion, and the cooling is uneven. The cooling rate is 900 ° C./s at the central portion and 1200 ° C./s at the edge, and the cooling rate is reduced by about 40% (1500 ° C./s to 900 ° C./s) compared with FIG. 6 in the central portion.
When there was a difference of 100 ° C. between the cooling rates of the plate width center part and the edge part of the steel plate, non-uniformity occurred.
As a result, it was shown that by applying the present invention, it is possible to prevent the cooling rate of the metal plate in the vicinity of the constraining roll from being reduced and prevent the cooling rate from being uneven in the plate width direction.

<Evaluation of tensile strength>
The tensile strength of the steel sheets manufactured according to Inventive Examples 1, 2, and 3 was about 1470 MPa in the entire sheet width direction.
On the other hand, the tensile strength of the steel sheet manufactured in Comparative Example 1 was about 1470 MPa in the central portion of the plate width, but was about 1550 MPa at the edge portion, showing uneven tensile strength.
In addition, the tensile strength of the steel sheet manufactured in Comparative Example 2 was about 1350 MPa at the center of the sheet width and about 1400 MPa at the edge portion, showing a decrease in tensile strength and nonuniformity.
When there was a difference of 30 MPa or more in the tensile strength between the central portion and the edge portion of the steel sheet, it was determined that the tensile strength was non-uniform.
From this, it is shown that by applying the present invention, it is possible to prevent the deterioration or non-uniformity of the characteristics of the steel sheet due to the decrease or non-uniformity of the cooling rate in the vicinity of the constraining rolls.

<Evaluation of warp amount>
The results of the amounts of warpage of the steel sheets measured in Inventive Examples 1, 2, and 3 and Comparative Examples 1 and 2 are shown in FIG.
In each of Inventive Examples 1, 2 and 3 and Comparative Examples 1 and 2, the warpage amount of the steel sheet is about the same, and the opening width of the opening portion of the adjacent nozzle is smaller in the end portion than in the central portion as in the present invention. However, it was confirmed that the deformation of the steel plate during quenching can be prevented.

According to the present invention, it is possible to prevent the non-uniformity of the cooling rate in the plate width direction of the metal plate while suppressing a decrease in the cooling rate of the metal plate while suppressing the shape defect that occurs in the metal plate during quenching. It is possible to provide an apparatus, a quenching method, and a method for manufacturing a steel sheet using the quenching method.

1 Water Tank 2 Water 3 Seal Roll 4 Spouting Device 5 Metal Plate 6 Sink Roll 7

Restraint Roll

14, 24

Nozzles

14a, 24a

Adjacent Nozzles

14b, 24b Adjacent Nozzles 14aA, 24aA Adjacent Nozzle Openings 14bA, 24bA Adjacent Nozzle Openings 14aB , 24aB Adjacent nozzle openings 14bB, 24bB Adjacent nozzle openings 14aX, 24aX Adjacent nozzle openings 14bX, 24bX

Adjacent nozzle openings

34, 44

Nozzle units

34a, 44a

Inlet nozzle units

34b, 44b Outgoing nozzle units

Claims

A bath containing a liquid for immersing a high-temperature metal plate,
At least a part is provided in the liquid of the tank, a jetting device including a plurality of nozzles for jetting the liquid on both surfaces of the metal plate,
A restraint roll that is provided between an inlet side end and an outlet side end of the ejection device and that holds the metal plate from both sides,
In the ejection device, at least the nozzle adjacent to the restraint roll is inclined from the direction perpendicular to the metal plate toward the restraint roll,
The opening of the nozzle adjacent to the constraining roll has a slit-like shape,
A quenching device, wherein the opening width of the opening is reduced from the central portion in the longitudinal direction of the opening to the end portion in the longitudinal direction.
The quenching device according to claim 1, wherein the opening width of the opening decreases discontinuously from the central portion in the longitudinal direction of the opening to the end portion in the longitudinal direction.
The quenching device according to claim 1, wherein the opening width of the opening continuously decreases from the central portion in the longitudinal direction of the opening to the end portion in the longitudinal direction.
The quenching device according to any one of claims 1 to 3, wherein the quenching device has a region having a uniform opening width in a central portion in the longitudinal direction of the opening.
A quenching method in which quenching is performed using the quenching device according to any one of claims 1 to 4.
A method for manufacturing a steel sheet, which uses the quenching method according to claim 5 when manufacturing a steel sheet.
The opening width of the opening is 2 mm or more and 5 mm or less at the central portion in the longitudinal direction of the opening, and is more than 0 mm and 3 mm or less at the end portions in the longitudinal direction of the opening, which is larger than the opening width of the central portion in the longitudinal direction. The quenching device according to any one of claims 1 to 3, characterized in that the opening width of the longitudinal end portion is small.