KR20230122656A - Metal plate quenching device and quenching method, and steel plate manufacturing method - Google Patents

Abstract

Provided are a metal plate quenching device and quenching method capable of suppressing shape defects occurring in the metal plate during quenching, and a steel plate manufacturing method. A cooling fluid spraying device formed on the exit side of the soaking zone of the continuous annealing furnace and having a plurality of jet nozzles for spraying mist on both sides of the continuously conveyed metal sheet; A device for quenching a metal plate comprising at least one pair of restraining rolls for restraining the metal plate from both sides in an area.

Description

Metal plate quenching device and quenching method, and steel plate manufacturing method

The present invention relates to a metal sheet quenching device and method for suppressing shape defects occurring in the metal sheet during quenching in a continuous annealing facility for annealing while continuously passing the metal sheet, and a steel sheet manufacturing method.

BACKGROUND OF THE INVENTION [0002] In the manufacture of metal sheets including steel sheets, in a continuous annealing facility, the metal sheet is cooled after being heated, and a phase transformation is caused to form the material. In recent years, in the automobile industry, demand for thinned high-strength steel sheets (high-ten) is increasing for the purpose of achieving both weight reduction of car bodies and crash safety. In the case of high ten manufacturing, the technology of rapidly cooling a steel plate becomes important. In this cooling, generally, mist in which gas and water are mixed or gas such as hydrogen is used as a cooling medium for the steel sheet. At that time, shape defects due to out-of-plane deformations such as warpage and wavy deformation occur in the steel sheet, which has become a problem. In order to prevent shape defects during quenching of such a steel sheet, various methods have been conventionally proposed.

For example, in Patent Document 1, a metal strip remains film boiling without transition boiling by appropriately controlling the water flow density of mist sprayed onto the strip. A method of mist cooling is disclosed.

Further, in Patent Literature 2, in a cooling zone in a vertical continuous annealing furnace in which the strip is continuously annealed while conveying it in the vertical direction, water contained in mist sprayed on the strip is caused by flowing down the surface of the strip, and the like. A technique for suppressing the occurrence of temperature unevenness in the width direction of one strip is disclosed.

Further, in Patent Document 3, when the temperature at the Ms point where the martensitic transformation of the metal sheet starts is T _Ms (° C.) and the temperature at the Mf point where the martensitic transformation ends is T _Mf (° C.), the metal sheet during rapid cooling and quenching is , a method of restraining the metal plate with a pair of restraining rolls formed in a cooling liquid in the range of (T _Ms +150) (°C) to (T _Mf -150) (°C) is disclosed.

Japanese Unexamined Patent Publication No. 2000-178658 Japanese Unexamined Patent Publication No. 2009-127060 Japanese Patent No. 6094722

However, as a result of verifying the methods described in Patent Literature 1 and Patent Literature 2, it was found that the shape defect suppression effect was small only by controlling the water density or suppressing the temperature unevenness in the width direction.

In addition, as a result of verifying the method described in Patent Literature 3, since the cooling method by immersing the steel sheet in liquid is excessively strong cooling, the cooling rate is liable to fluctuate, and as a result, the temperature of the steel sheet when passing through the restraining rolls is liable to fluctuate. , there was a case where a large variation in the amount of warpage occurred in the longitudinal direction, and there was room for improvement.

The present invention has been made to solve these problems, and an object of the present invention is to provide a metal plate quenching device and quenching method capable of suppressing shape defects occurring in the metal plate during quenching, and a steel plate manufacturing method.

The present inventors obtained the following recognition as a result of repeating earnest examination in order to solve such a problem. In the metal sheet manufacturing method, there are cases in which structure control that causes martensitic transformation to occur in the metal sheet is used during quenching. However, when martensitic transformation occurs, the structure expands in volume, resulting in a complicated and non-uniform concavo-convex shape. may be thrown away. When a high-strength steel sheet having a martensitic structure is quenched, the greatest stress acts on the steel sheet from the vicinity of the Ms point to the Mf point where transformation expansion occurs during thermal contraction, and the shape collapses. In addition, at this time, the cooling rate fluctuates more easily if it is strong cooling. Therefore, after cooling using mist that is not too strongly cooled, in the range where the temperature of the metal plate is from the Ms point to the Mf point, the amount of warpage can be sufficiently reduced by arranging a restraining roll that restrains the metal plate. Here, the Ms point refers to the temperature at which martensitic transformation starts, and the Mf point is the temperature at which martensitic transformation ends.

The present invention has been made based on the above recognition and idea, and has the following characteristics.

[1] A cooling fluid spraying device formed on the exit side of a soaking zone of a continuous annealing furnace and having a plurality of spray nozzles for spraying mist on both sides of a continuously conveyed metal plate;

A metal plate quenching device comprising at least one pair of restraining rolls for restraining the metal plate from both sides in a region from a cooling start point to a cooling end point by the cooling fluid ejection device.

[2] The quenching of the metal sheet according to [1], wherein the plurality of jet nozzles are arranged so as to spray the mist to the metal sheet in the entire temperature range from the martensitic transformation start temperature to the martensitic transformation end temperature of the metal sheet. Device.

[3] The metal plate quenching device according to [1] or [2], wherein a dewatering spray nozzle is provided downstream of the outlet of the cooling fluid ejection device.

[4] Mist is sprayed on both sides of a continuously transported metal sheet to cool it, and the metal sheet is coated on both sides in a region where the temperature of the metal sheet during cooling is at least between the martensitic transformation start temperature and the martensitic transformation end temperature. A method of quenching a metal plate, restrained from.

[5] The method for quenching a metal sheet according to [4], wherein the water density of the mist is 100 L/m2·min or more and 800 L/m2·min or less.

[6] The steel sheet is continuously annealed, and further quenched according to the metal sheet quenching method described in [4] or [5], and any of high-strength cold-rolled steel sheet, hot-dip galvanized steel sheet, electro-galvanized steel sheet, and alloyed hot-dip galvanized steel sheet is obtained. A method for producing a steel plate for manufacturing things.

According to the device and method for quenching a metal sheet and the method for manufacturing a steel sheet according to the present invention, shape defects occurring in a metal sheet during quenching can be effectively suppressed.

1 is a diagram showing an example of a metal plate quenching device and quenching method of the present invention.
2 : is a figure which shows an example of the air and water supply system to the mist ejection nozzle in the quenching apparatus of the metal plate of this invention.
3 is a diagram showing an example of a two-fluid nozzle.
Fig.4 (a) and FIG.4(b) is a figure which shows the example of a mist ejection nozzle.
5(a) and 5(b) are diagrams showing mist cooling and conventional water quenching according to the metal plate quenching device and quenching method of the present invention, respectively.
Fig. 6 is a diagram showing another example of a metal plate quenching device and quenching method according to the present invention.
Fig. 7 is a graph showing the effects of the metal sheet quenching device and quenching method of the present invention, compared with those of a comparative example.
FIG. 8 is a diagram showing the definition of the amount of warp of the metal plate in FIG. 7 .

(Mode for implementing the invention)

EMBODIMENT OF THE INVENTION Hereinafter, with reference to drawings, embodiment of the metal plate quenching apparatus, metal plate quenching method, and steel plate manufacturing method of this invention is demonstrated concretely.

1 is a diagram showing a metal plate quenching device according to an embodiment of the present invention. This quenching device is applied to a cooling facility formed on the exit side of a soaking zone in a continuous annealing furnace. When the metal sheet to be cooled is a steel sheet, this cooling facility is provided in order to transform the austenite phase to martensite during cooling of the steel sheet and obtain mechanical properties of the final product. Therefore, it is provided with the ability to cool the range including the temperature range from the martensitic transformation start temperature to the martensitic transformation end temperature.

As shown in FIG. 1, the metal plate quenching device of this embodiment is a cooling fluid ejection device composed of a plurality of mist ejection nozzles (jet nozzles) 2, and a metal plate 1 in a cooling region by the cooling fluid ejection device. It is provided with at least a pair of restraining rolls 3 and a dewatering spray nozzle 4 which restrain the . The mist ejection nozzle 2 sprays mist 2a as a refrigerant (cooling fluid) to the metal plate 1 from both sides of the continuously passing metal plate (for example, steel plate) 1 to rapidly cool it. The restraining roll 3 restrains the metal plate 1 in the region from the cooling start point, which is the inlet of the cooling fluid ejection device, to the cooling end point, which is the outlet, to prevent deformation. The dehydration spray nozzle 4 is formed on the downstream side of the outlet of the cooling fluid spraying device, and sprays gas 4a such as air or nitrogen to the metal plate 1 from the outlet side of the metal plate 1 so as to cool the metal plate 1. Drain the water stream.

Here, mist is water or liquid in the form of mist, and refers to a state in which minute droplets having a droplet diameter of about 0.01 μm to several hundreds of μm are suspended in a gas. In this embodiment, the above-mentioned mist is generated by mixing and spraying water and air. A sufficient cooling rate can be obtained by spraying air while water in the form of minute droplets adheres to the metal plate to be cooled. In addition, since water and air reach the metal plate in a mixed state, the cooling rate can be made more gentle and stable than in the case of spraying only water.

Here, when the droplet diameter of the mist is less than 10 μm, water droplets evaporate easily and a sufficient cooling rate may not be obtained. Moreover, when the droplet diameter of the mist exceeds 100 µm, water in the form of water droplets may adhere to and remain on the metal plate, which tends to cause uneven cooling. Therefore, it is preferable that the droplet diameter of the mist is 10 μm or more and 100 μm or less.

For the mist ejection nozzle 2, products such as slit nozzle PSN manufactured by Ikeuchi Co., Ltd. and knife jet KJIS type manufactured by Kyoritsugo Kinsei Co., Ltd. (internal mixing type) can be used, for example.

In FIG. 2, the supply system of air and water to the mist ejection nozzle 2 in the quenching apparatus of the metal plate of this embodiment is schematically shown. 3 schematically shows a two-fluid nozzle used as the mist ejection nozzle 2 in this embodiment. In this embodiment, the case where mist is generated using the two-fluid nozzle shown in FIG. 3 as the mist ejection nozzle 2 is demonstrated as an example, but the mist ejection nozzle is not limited to this and can eject mist in a suitable flow rate range. It's good if you can.

When using a two-fluid nozzle as the mist blowing nozzle 2, as shown in FIG. 2 , compressed air fed under pressure from the compressor 52 is supplied to the mist blowing nozzle 2 via the compressed air piping 5. do. Moreover, the water pumped by the pump 63 from the water tank 62 is supplied to the mist ejection nozzle 2 through the water pipe 6. Here, the opening of the supply valve 51 formed in the compressed air pipe 5 and the supply valve 61 formed in the water pipe 6, and the operation of the pump 63, to the flow control device 7 controlled by In this way, what is necessary is just to supply compressed air and water so that the pressure and quantity of the compressed air and water supplied to the mist ejection nozzle 2 may fall within the range permitted by the specification of the mist ejection nozzle 2. Moreover, in order to avoid clogging of the mist ejection nozzle 2, you may make it provide a filter rather than the supply valve 61 of the water pipe 6 to the mist ejection nozzle 2 side.

Here, when the air-to-water-volume ratio of the mist ejected from the mist ejection nozzle 2 is less than 50, adhesion and retention of water to the metal plate 1 become significant, causing uneven cooling. easy. In addition, when the brackish water volume ratio exceeds 1000, the droplet diameter of the mist becomes too small, and the cooling rate necessary for obtaining the characteristics required of the metal plate 1 may not be obtained. Therefore, it is preferable to make the steam volume ratio of the mist injected from the mist ejection nozzle 2 into 50-1000.

In the quenching device of the metal plate of this embodiment, the mist ejection nozzle 2 is arranged in 80 rows at intervals of 200 mm in the steel plate advancing direction (steel plate longitudinal direction).

However, the arrangement|positioning of the mist ejection nozzle 2 is not limited to this, What is necessary is just to arrange|position so that cooling unevenness may not arise in the width direction of the metal plate 1. For example, as shown in FIG.4(a), when using 2 A of slit nozzles wider than the width of the metal plate 1 as the mist ejection nozzle 2, the nozzle spacing I of the steel plate advancing direction It is preferable to arrange slit nozzles so that this becomes 100-600 mm. If the nozzle interval I in the steel sheet advancing direction is less than 100 mm, the mist blowing area between the nozzles may interfere, making it difficult to predict the cooling rate. If it exceeds, it is because a sufficient cooling rate may not be obtained.

Moreover, as shown in FIG.4(b), when using the nozzle 2B whose spray pattern becomes a spot shape or a conical shape as the mist ejection nozzle 2, the nozzle specification Accordingly, it is preferable to arrange the plurality of nozzles 2B in a row in the width direction of the metal plate 1 . At this time, it is preferable that the mist blowing area of each nozzle 2B overlaps without gaps or sufficiently so that a uniform cooling rate can be obtained in the width direction of the metal plate 1. Moreover, as shown in FIG.4(b), it is preferable to attach and use the several nozzle 2B arranged side by side in the width direction of the metal plate 1 to the header 21.

In addition, the mist ejection nozzle 2 may be arranged in a zigzag manner, and the inclination angle of the spraying direction of the mist from the mist ejection nozzle 2 relative to the metal plate 1 or the diffusion of the spray spread in a conical shape. You may adjust an angle according to the width|variety of the metal plate 1 used as cooling object, etc.

In this way, even when a plurality of nozzles arranged side by side in the width direction of the metal plate 1 are used as a nozzle set so as to obtain a uniform cooling capacity in the width direction of the metal plate 1, the interval between the nozzle sets in the direction of the steel plate travel It is preferable to make (I) 100-600 mm. When the interval I between the nozzle sets in the steel plate advancing direction is less than 100 mm, mist blowing areas between the nozzles may interfere, making it difficult to predict the cooling rate, and the interval I between the nozzle sets exceeds 600 mm. This is because there are cases where a sufficient cooling rate cannot be obtained.

Here, in the present invention, in the temperature range where the shape of the metal plate 1 is most disturbed by the cooling capacity of the cooling fluid spraying device (mist spraying nozzle) 2 and the positional relationship of the constraining roll 3, It is important to restrain the metal plate 1 using the restraining roll 3 . Then, in the quenching apparatus and quenching method of the metal plate of this embodiment, it is preferable to set the amount of mist which controls cooling capacity, and the water temperature of mist as follows.

First, when performing the quenching method of cooling by spraying the mist 2a on the surface of the metal plate 1 from the some mist ejection nozzle 2, the water density of the mist 2a is 100 L/m<2>*min or more 800 L/min. It is preferable to set it as m2*min or less. When the water density of the mist 2a is less than 100 L/m 2 ·min, the mechanical properties of the steel sheet are not obtained, and the position of the restraining roll increases from the cooling start position to a long distance, resulting in an increase in the size of the facility. In addition, when the water density of the mist 2a exceeds 800 L/m 2 min, the cooling time from the start of cooling to the arrival of the restraining roll becomes short, the cooling becomes unstable, and the shape is disturbed to the extent that the restraining roll cannot be corrected. Because there are times when you lose.

Moreover, as for the water density of the mist 2a, it is more preferable to set it as 200 L/m<2>*min or more and 500 L/m<2>*min or less.

In addition, the temperature of the cooling water constituting the particles of the mist 2a is preferably greater than 0°C and not greater than 60°C, and particularly not greater than 10°C and not greater than 50°C, from the viewpoints of maintaining facilities and obtaining a sufficient cooling rate. desirable. This is because when the temperature is lower than 0 ° C., there is a risk of damage to the equipment due to freezing, and when the temperature is higher than 60 ° C., the cooling rate slows down, and the position of the restraining roll becomes longer from the cooling start position, resulting in an increase in the size of the equipment.

In addition, in the vertical mist cooling device, since the water contained in the mist 2a falls downward along the metal plate 1 and adversely affects the cooling of the lower part, it is preferable to take measures to prevent water flow, for example It is controllable by spraying mist 2a or gas 4a toward about 30 degrees upward.

At that time, for the reasons described above, it is preferable to set the cooling rate of the metal plate 1 to 50°C/sec or more and 500°C/sec or less in order to arrange a practical and effective constraining roll depending on the cooling capacity. When it becomes less than 50 degreeC/sec, the distance from the cooling start point to a restraining roll becomes a long distance, resulting in enlargement of a facility. On the other hand, if it exceeds 500°C/sec, the cooling time from the start of cooling to the arrival of the constraining roll becomes short, the cooling becomes unstable, and the shape may be disturbed to the extent that the constraining roll cannot be corrected.

Thus, the shape correction effect by the restraining roll 3 can be improved by using mist 2a and controlling so that it may become a suitable cooling rate range.

In this embodiment, when performing the quenching method to cool by spraying the mist 2a from the some mist ejection nozzle 2 on the surface of the metal plate 1, the temperature of the metal plate 1 is in the range from Ms point to Mf point In the present invention, a restraining roll 3 for restraining the metal plate 1 is disposed. Here, the Ms point refers to the temperature at which the martensitic transformation of the metal sheet 1 starts, and the Mf point refers to the temperature at which the martensitic transformation ends. In addition, the temperature of Ms point or Mf point is computable from the component composition of the metal plate 1.

The constraining roll 3 is formed by sandwiching the metal plate 1 from the front and back surfaces in order to prevent deformation that may occur during quenching of the metal plate 1 . The pair of constraining rolls 3 are preferably disposed with their central axes shifted in the transport direction of the metal plate 1 . By arranging the center axis shifted, the restraining force of the metal plate 1 can be increased and the shape correcting force can be increased. As an example, it is preferable to arrange the restraining rolls 3 so that each central axis is shifted by 40 mm or more and 150 mm or less in the conveying direction, and it is more preferable to displace them by 80 mm or more and 100 mm or less.

Moreover, it is preferable to press-fit the metal plate 1 with the restraining roll 3, and to plate through so that the metal plate 1 may be wound around the restraining roll 3. By press-fitting the metal plate 1, while being able to raise the straightening force of a steel plate, revolution of the restraining roll 3 can be prevented. The amount of press-in by one constraining roll 3 is preferably set to 0 mm or more and 2.5 mm or less when the case where the metal plate 1 is linearly plated is taken as a reference (0 mm) as shown in FIG. , It is more preferable to set it as 0.5 mm or more and 1.0 mm or less.

5(a) and 5(b), mist cooling according to the quenching device and quenching method of the metal plate of the present embodiment and conventional water quenching are shown in contrast. As shown in Fig. 5(a), by performing the cooling from the Ms point to the Mf point gently by mist cooling, the distance from the Ms point to the Mf point is greater than that of the conventional water quenching shown in Fig. 5(b). (L) becomes longer. Therefore, it is desirable to flexibly respond to changes in the plate-threading speed or sheet thickness of the metal sheet 1, to use the restraint rolls 3 in an appropriate temperature range, or to increase or decrease the number of restraint rolls 3 used for restraint. , easier than conventional water quenching.

For example, considering the case where the sheet thickness x sheet passing speed is 1.5 (m/sec) mm and the temperature difference between the Ms point and the Mf point is 100°C, in the water quenching shown in FIG. 5(b), the cooling rate is 1500 If it is °C/(sec·mm), the distance L from the Ms point to the Mf point is 100 mm. On the other hand, in the mist cooling shown in FIG.5(a), the cooling rate becomes about 300 degreeC/(sec.mm), and the distance L from Ms point to Mf point can be expanded to 500 mm. Then, by forming a plurality of restraining rolls 3 in a section of the distance L (500 mm) from the Ms point to the Mf point, the metal plate 1 is reliably restrained in the temperature range from the Ms point to the Mf point, , shape correction can be performed reliably. In addition, it is easy to flexibly respond to fluctuations in abnormal constraint positions such as changes in sheet-threading speed or sheet thickness.

Here, in the metal plate quenching device and quenching method of the present embodiment shown in Fig. 5 (a), when the distance L from the Ms point to the Mf point is less than 200 mm, the water shown in Fig. 5 (b) As in the case of quenching, it becomes difficult to flexibly respond to changes in the sheet-threading speed or sheet thickness of the metal sheet 1 . Therefore, there are cases where the shape correcting effect by the constraining roll 3 is not sufficiently obtained. In addition, when the distance (L) from the Ms point to the Mf point exceeds 1000 mm, martensitic transformation becomes insufficient, and desired material properties may not be obtained. Therefore, in order to effectively obtain the shape correcting effect by the constraining roll 3 in the region from the Ms point to the Mf point, it is preferable to secure the distance L from the Ms point to the Mf point about 200 to 1000 mm.

Moreover, you may use the mist 2a over the whole length of the area|region which requires cooling of the metal plate 1, including the high temperature side rather than Ms point, and the low temperature side than Mf point.

In order to prevent roll flaws in the metal plate 1 from occurring, it is preferable to rotate the constraining roll 3 in the circumferential direction by rolling. In addition, in order to adjust the straightening force of the metal plate 1, it is preferable that the constraining roll 3 can be opened and closed as needed (the amount of pushing into the metal plate 1 can be controlled).

The constraining roll 3 should just be formed of a material with excellent thermal conductivity and strength capable of withstanding the load at the time of clamping the metal plate 1 . As a material of the constraining roll 3, SUS304 or SUS310 prescribed|regulated by Japanese industrial standard JISG4304 "hot-rolled stainless steel sheet and steel strip", ceramics, etc. are mentioned, for example.

Next, an example using three or more constraining rolls 3 will be described with reference to FIG. 6 . In the following, description of points similar to the case of using the pair of constraining rolls 3 may be omitted.

In the example of Fig. 6, the front and back surfaces of the metal plate 1 are restrained by four (two pairs) restraint rolls 3. Also in the example in which a plurality of pairs of constraint rolls are formed, it is preferable to press-in the metal plate 1 with the constraint rolls for the same reason as in the example in which only two (one pair) of constraint rolls are formed. 0 mm or more and 2.5 mm or less are preferable, and, as for the press-in amount in each constraining roll, 0.5 mm or more and 1.0 mm or less are especially preferable. The number of restraint rolls 3 respectively disposed on the front and back surfaces of the metal plate 1 may not necessarily be the same. However, in order to equally impart restraining force from both sides of the metal plate 1, the same number of restraining rolls 3 are arranged in pairs on the front and back surfaces of the metal plate 1, or on the front and back surfaces of the metal plate 1. It is preferable to make the difference of the number of the restraining rolls 3 arrange|positioned become one.

In the example in which three or more constraining rolls are provided, the shape correcting force of the steel sheet during cooling can be further increased compared to the case in which only two (one pair) are provided. In particular, even when cooling a high-strength steel sheet that is prone to deformation, deformation such as warpage of the steel sheet during cooling can be further suppressed by providing three or more constraining rolls. On the other hand, if the number of restraint rolls is excessively increased, there are also problems of equipment constraints and cooling capacity in the ejection device, so the number of restraint rolls may be appropriately determined in view of these problems.

In addition, as in the present embodiment, when the cooling by the mist 2a and the restraining roll 3 are used together, the mist 2a adheres to and stays on the restraining roll 3, and the amount of adhesion and retention of these droplets is reduced to the metal plate. It may become non-uniform in the width direction of (1) (ie, the axial direction of the constraining roll 3). As a result, there is a case where cooling unevenness occurs and the shape correcting effect by the constraining roll 3 is reduced. Therefore, in order to solve such a problem, a dewatering mechanism (not shown) may be provided near the restraining roll 3 to remove liquid droplets adhering to and remaining on the restraining roll 3 . Specifically, as a dewatering mechanism, an obstacle on a blade, a wiper, an air nozzle, or the like can be used.

As described above, the present invention aims to reduce the complex and non-uniform concavo-convex shape that occurs when martensitic transformation occurs during rapid cooling of a steel sheet and the structure expands in volume, and the present invention provides a high-strength steel sheet (high Ten) is preferably applied to the manufacturing method.

More specifically, it is preferable to apply to manufacture of a steel plate whose tensile strength is 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.

Examples of the high-strength steel sheet (HITEN) include high-strength cold-rolled steel sheets and hot-dip galvanized steel sheets subjected to surface treatment, electro-galvanized steel sheets, alloyed hot-dip galvanized steel sheets, and the like.

As specific examples of the composition of the high-strength steel sheet, in mass%, C is 0.04% or more and 0.25% or less, Si is 0.01% or more and 2.50% or less, Mn is 0.80% or more and 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, if necessary, at least one of Cr, Mo, Nb, V, Ni, Cu, and Ti is 0.5% or less each, further If necessary, an example in which each of B and Sb is 0.01% or less, and the balance consists of Fe and unavoidable impurities is exemplified.

In addition, the embodiment of the present invention is not limited to an example in which a steel sheet is quenched, and can be applied to quenching of metal sheets in general other than the steel sheet.

Example

Applying the metal sheet quenching device and quenching method of the present invention, and the steel sheet manufacturing method, a steel sheet manufacturing test was performed and the effect was verified, so this will be described.

(Example 1 of the present invention)

Using the metal sheet quenching device shown in FIG. 1, a high-strength cold-rolled steel sheet with a sheet thickness of 1.0 mm and a sheet width of 1000 mm and a tensile strength of 1470 MPa class was plated at a sheet-threading speed of 1.0 m/s, a quenching start temperature of 800 ° C., and a mist water density of 400 L / m 2 -min, the temperature at the time of passage of the constraining rolls was 350°C.

Here, as the composition of the high-strength cold-rolled steel sheet having a tensile strength of 1470 MPa class, C was 0.20%, Si was 1.0%, Mn was 2.3%, P was 0.005%, and S was 0.002% in terms of mass%.

In addition, the temperature of the Ms point of the high-strength cold-rolled steel sheet is 400°C, and the temperature of the Mf point is 300°C. Therefore, as described above, since the temperature at the time of passing the constraining roll may be set within the range of 400°C to 300°C, here it is set at 350°C as described above.

Here, the central axes of the constraining rolls were displaced by 80 mm in the plate-threading direction, and the amount of pressing of the constraining rolls 3 into the metal plate 1 was all set to 0.5 mm.

(Example 2 of the present invention)

Using the quenching apparatus shown in Fig. 6, the operation was performed under the same conditions as in Example 1 of the present invention. In addition, the central axes of the opposing restraining rolls were all arranged shifted by 80 mm in the plate-threading direction, and the amount of pressing into the metal plate 1 by the restraining roll 3 was all set to 0.5 mm.

(Comparative Example 1)

As a comparative example, the above high-strength cold-rolled steel sheet was manufactured using the cooling device shown in Patent Literature 1, and other conditions were the same as those of the present invention example.

(Comparative Example 2)

As a comparative example, the above high-strength cold-rolled steel sheet was manufactured using the cooling device shown in Patent Literature 2, and other conditions were the same as those of the present invention example.

(Comparative Example 3)

As a comparative example, the above high-strength cold-rolled steel sheet was manufactured using the cooling device shown in Patent Literature 3, and other conditions were the same as those of the present invention example.

Then, in each case (Examples 1 to 2 of the present invention and Comparative Examples 1 to 3), 10 steel sheets after cooling were sampled at intervals of 100 m in the longitudinal direction, and the amount of warping of each steel sheet was investigated. Further, the definition of the amount of warpage is shown in FIG. 8 . Specifically, the height of the highest position when the steel plate was placed on a horizontal surface was defined as the amount of warpage.

The results of Examples 1 to 2 of the present invention and the results of Comparative Examples 1 to 3 are shown in FIG. 7 .

In Examples 1 and 2 of the present invention, the amount of warpage of the steel sheet was reduced in the range of 2.0 to 8.0 mm, and was suppressed to 10 mm or less in the entire longitudinal direction. On the other hand, in Comparative Examples 1 and 2, the warp amount of the steel sheet was distributed in a range of 10.0 to 14.0 mm, and the deformation suppression effect was insufficient throughout the longitudinal direction. Further, in Comparative Example 3, the warpage amount of the steel sheet was non-uniform in the range of 4.0 to 14.0 mm, and was not suppressed in the range of 10 mm or less in the entire longitudinal direction.

In this regard, the effectiveness of the metal sheet quenching device and quenching method, and the steel sheet manufacturing method of the present invention was confirmed.

1: metal plate
2 (2A, 2B): mist ejection nozzle (jet nozzle)
2a: Mist
21: Header
3: restraint roll
4: Dewatering spray nozzle
4a: gas
5: compressed air piping
51: supply valve
52: Compressor
6 : water piping
61: supply valve
62: water tank
63: pump
7: flow control device

Claims (6)

It is formed on the exit side of the crack zone of the continuous annealing furnace,
A cooling fluid spraying device having a plurality of spray nozzles for spraying mist on both sides of a continuously conveyed metal plate;
A metal plate quenching device comprising at least one pair of restraining rolls for restraining the metal plate from both sides in a region from a cooling start point to a cooling end point by the cooling fluid ejection device. According to claim 1,
The quenching device for a metal sheet according to claim 1 , wherein the plurality of spray nozzles are arranged to spray the mist to the metal sheet in the entire temperature range from a martensitic transformation start temperature to a martensitic transformation end temperature of the metal sheet. According to claim 1 or 2,
A metal plate quenching device comprising a dewatering spray nozzle on a downstream side of an outlet of the cooling fluid spraying device. Mist is sprayed on both sides of a continuously conveyed metal sheet to cool it, and the metal sheet is restrained from both sides in a region where the temperature of the metal sheet during cooling is at least between the martensitic transformation start temperature and the martensitic transformation end temperature. , the quenching method of the metal plate. According to claim 4,
The quenching method of the metal plate which makes the water flow density (water flow density) of the said mist into 100 L/m<2>*min or more and 800 L/m<2>*min or less. A steel sheet is continuously annealed and further quenched according to the metal sheet quenching method according to claim 4 or 5 to produce a high-strength cold-rolled steel sheet, a hot-dip galvanized steel sheet, an electro-galvanized steel sheet, or an alloyed hot-dip galvanized steel sheet. Manufacturing method of steel sheet.