JP6687084B2 - Quenching and quenching apparatus, quenching and quenching method, and method for manufacturing metal plate product - Google Patents

Description

  The present invention, in a continuous annealing equipment that performs annealing while continuously passing a metal plate, a quenching quenching apparatus and a quenching quenching method that can suppress variation in shape that occurs in the metal sheet during quenching quenching, and a metal sheet product. Manufacturing method.

  In the production of metal sheets such as steel sheets (metal sheet products), in a continuous annealing facility that performs annealing while continuously passing the metal sheet, the metal sheet is heated and then cooled to cause a phase transformation. And build 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-strength steel sheets, technology for rapidly cooling the steel sheets 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, a heated steel plate is immersed in water, and at the same time, quench water is quenched and quenched by injecting cooling water into the steel plate by a quench nozzle provided in the water. When quenching and 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 during quenching and quenching of a steel sheet, various methods have been conventionally proposed.

For example, in Patent Document 1, when the temperature of the Ms point at which the martensitic transformation of the metal plate starts is T _Ms (° C.) and the temperature at the Mf point at which the martensitic transformation ends is T _Mf (° C.), quenching and quenching are in progress. a metal plate, in the range is the temperature of the metal sheet from _{(T Ms +150) (℃)} (T Mf -150) (℃), a technique for constraint proposed by a pair of constraining rolls provided in the cooling liquid ing.

This is because the metal plate undergoes heat contraction when it is rapidly cooled by the cooling liquid, and in particular, the metal plate undergoes the martensite transformation from the point Ms where the temperature of the metal sheet is the temperature at which the martensite transformation starts. when a Mf point is the temperature, caused rapid thermal contraction and transformation expansion at the same time, stress acting on the metal plate becomes largest, since the shape is lost, the temperature of the metal sheet (T _Ms +150) (℃ ) To ( _TMf- 150) (° C), a restraining roll for restraining the metal plate is arranged. The reason for setting the position of the constraining roll to the region ± 150 ° C from the Ms point to the Mf point is that it was confirmed in the experiment that the warp amount was sufficiently reduced in this range (paragraph of Patent Document 1). [0018], [0019], see FIGS. 2 and 4.

  Further, Patent Document 2 proposes a method of blocking the ejection of the cooling liquid in the strip width direction and / or the line direction to adjust the effective cooling width and / or the effective cooling length of the strip.

Japanese Patent No. 6094722 JP-A-60-194022

However, although the method described in Patent Document 1 can certainly prevent the deformation of the metal plate at the time of quenching and quenching, the temperature of the metal plate is (T _Ms +150) (° C) to (T) depending on the manufacturing conditions of the metal plate. _mf -150) (for range comprising positions of ° C.) is changed, the temperature of the metal plate is a _{(T Ms +150) (℃)} ~ (T Mf -150) (℃) a position in restraint roll the metal plate In some cases, the restraint roll cannot always be effective because it cannot be restrained. As a result, there is a problem in that the shape of the metal plate varies depending on the manufacturing conditions of the metal plate, and the processing in the subsequent steps becomes complicated.

  Further, in the method described in Patent Document 2, there is a problem that the cooling stop temperature cannot be controlled but the cooling start position cannot be controlled.

  The present invention has been made to solve such a problem, and in a continuous annealing facility that performs annealing while continuously passing a metal plate (for example, a steel plate), a metal plate that occurs during quenching and quenching. It is an object of the present invention to provide a quenching and quenching apparatus, a quenching and quenching method, and a method for producing a metal plate product, which can suppress the variation in shape due to the above manufacturing conditions.

  As a result of intensive studies to solve such a problem, the present inventors have obtained the following findings and ideas.

  That is, in quenching and quenching a metal plate (for example, a steel plate), the temperature of the metal plate decreases according to the distance from the cooling start position. Therefore, by adjusting the cooling start position of the metal plate and controlling the cooling distance from the cooling start position to the constraining roll, the constraining roll can always exhibit the same effect. Further, in quenching and quenching a metal plate, it is not always necessary to immerse the metal plate in water, and if a sufficient amount of water is sprayed from a nozzle, a cooling capacity equivalent to that in water is obtained.

  The present invention is based on the above findings and ideas, and has the following features.

[1] A quenching and quenching device for cooling a metal plate while continuously passing it through,
A cooling fluid ejecting device comprising a plurality of nozzles for ejecting a cooling fluid to the metal plate from both sides of the metal plate,
A pair of restraint rolls for restraining the metal plate,
It is provided between the nozzle and a metal plate passage line through which the metal plate passes, and adjusts a cooling start position of the metal plate by the cooling fluid to control a distance from the cooling start position to the restraint roll. A quenching and quenching device, which is equipped with movable masking.

[2] When the temperature of the Ms point where the martensite transformation of the metal plate starts is T _Ms (° C.) and the temperature of the Mf point where the martensite transformation ends is T _Mf (° C.), the metal plate is The quenching and quenching apparatus according to the above [1], wherein the quenching and quenching apparatus is configured to pass through the constraining roll at a temperature of _Ms +150) (° C) to ( _TMf- 150) (° C).

  [3] The quenching and quenching apparatus as described in [1] or [2] above, wherein the movable masking is provided with an air jet nozzle.

  [4] A quenching and quenching method of cooling by spraying cooling fluid from a plurality of nozzles onto the surface of a metal plate that is continuously passed, wherein the metal plate is constrained by a constraining roll and the cooling is performed by movable masking. A quenching and quenching method comprising adjusting a cooling start position of the metal plate by a fluid and controlling a distance from the cooling start position to the constraining roll.

[5] When the temperature of the Ms point at which the martensitic transformation of the metal plate starts is T _Ms (° C.) and the temperature at the Mf point at which the martensitic transformation ends is T _Mf (° C.), the metal sheet is (T The quenching and quenching method as described in [4] above, wherein the binding roll is passed at a temperature of _Ms +150) (° C) to ( _TMf- 150) (° C).

  [6] The distance from the cooling start position of the metal plate to the constraining roll is defined as the sheet passing speed of the metal plate, the quenching start temperature, the target temperature of the metal plate when passing through the constraining roll, and the cooling of the metal plate. The quenching and quenching method as described in [4] or [5] above, which is set based on the speed.

[7] Passing speed of the metal plate is v (mm / s), quenching start temperature is T ₁ (° C.), target temperature when passing through the constraining roll is T ₂ (° C.), cooling rate of the metal plate Is the CV (° C / s), and the distance d (mm) from the cooling start position of the metal plate to the constraining roll is represented by the following formula: The rapid quenching and quenching method according to the above [6].
d = (T ₁ −T ₂ ) v / CV

  [8] The distance from the cooling start position of the metal plate to the constraining roll is defined as the sheet passing speed of the metal plate, the quenching start temperature, the target temperature of the metal plate when passing through the constraining roll, the cooling condition, the metal. The quenching and quenching method as described in [4] or [5] above, which is set based on the plate thickness of the plate.

[9] the sheet passage speed of the metal plate v (mm / s), the quenching start temperature T _{1 (℃),} the temperature during passage constraining rolls the target T ₂ and _(° C.), constants determined by the cooling conditions The distance d (mm) from the cooling start position of the metal plate to the constraining roll is represented by the following formula using α (° C · mm / s) and the plate thickness t (mm) of the metal plate. The quenching and quenching method according to [8] above.
d = (T ₁ −T ₂ ) vt / α

  [10] A method for producing a metal plate product, which comprises performing rapid quenching and quenching using the quenching and quenching method according to any one of [4] to [9] above when producing a metal plate product.

  [11] The method for producing a metal plate product according to the above [10], wherein the metal plate product is any one of a high-strength cold-rolled steel plate, a hot-dip galvanized steel plate, and an alloyed hot-dip galvanized steel plate.

  In the present invention, in a continuous annealing facility that performs annealing while continuously passing a metal plate (for example, a steel plate), it is possible to suppress variation in shape due to manufacturing conditions of the metal plate, which occurs during quenching and quenching.

It is a figure which shows the quenching quenching apparatus which concerns on Embodiment 1 of this invention. It is a figure which shows the quenching quenching apparatus which concerns on Embodiment 2 of this invention. It is a graph which shows the result (temperature at the time of passing a restraint roll) of the example of the present invention. It is a graph which shows the result (warpage amount) of an example of the present invention. It is a graph which shows the result (temperature at the time of passing a restraint roll) of a comparative example. It is a graph which shows the result (warpage amount) of a comparative example. It is a figure which shows the definition of the amount of curvatures in FIG. 4 and FIG.

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

[Embodiment 1]
FIG. 1 is a diagram showing a quenching and quenching apparatus 11 according to Embodiment 1 of the present invention. This quenching quenching device 11 can be applied to a cooling facility provided on the outlet side of the soaking zone of a continuous annealing furnace.

  As shown in FIG. 1, the quenching and quenching apparatus 11 according to the first embodiment includes a water 2a that is a refrigerant (cooling fluid) on both sides of a metal plate (for example, a steel plate) 1 that is continuously passed through the metal plate 1. A plurality of water jet nozzles 2 (cooling fluid jetting devices) for jetting water and rapid cooling, and a metal plate passing line through which the water jet nozzles 2 and the metal plate 1 pass, and a metal plate with a cooling fluid is provided. 1 includes a movable masking 3 for adjusting the cooling start position of 1, and a pair of constraining rolls 5 for constraining the metal plate 1 to prevent deformation. Further, a shielding cover 6 is installed around the quenching and quenching device 11 in order to prevent the water 2a sprayed from the water spray nozzle 2 from splashing to the surroundings. A sink roll 4 that changes the transport direction (passing direction) of the metal plate 1 is provided on the exit side of the restraining roll 5.

As a result, in the first embodiment, when performing the quenching quenching method of cooling the surface of the metal plate 1 by injecting water 2a from the plurality of water ejection nozzles 2, the martensitic transformation of the metal plate 1 starts Ms. When the temperature of the point is T _Ms (° C.) and the temperature of the Mf point at which the martensitic transformation ends is T _Mf (° C.), the metal plate 1 is restrained by the restraining roll 5 and the metal by the cooling fluid is cooled by the movable masking 3. controlling the distance to the constraining rolls 5 from the cooling start position of the plate 1 (the lower end of the movable masking 3), a metal plate 1 _(T Ms +150) (° _C.) restraint at a temperature of ~ (T Mf -150) (° C.) The roll 5 is passed.

Here, so that passing the restraining roll 5 at a temperature of the metal plate _{1 (T Ms +150) (℃} ) ~ (T Mf -150) (℃) are shown in the aforementioned Patent Document 1 As described above, the metal plate 1 is heat-contracted by being rapidly cooled by the cooling liquid, and in particular, the metal plate 1 has a temperature of the metal plate 1 from the Ms point at which the martensite transformation starts, to martensite. When the temperature reaches the Mf point, which is the temperature at which the transformation ends, abrupt thermal contraction and transformation expansion occur at the same time, the stress acting in the metal plate 1 becomes the largest, and the shape collapses. in T _Ms +150) (a from _{℃) (T Mf -150) (} ℃) range, and a metal plate 1 so as to pass through while restrained by restraining roll 5. The reason why the position of the restraint roll 5 is set to a region ± 150 ° C. from the Ms point to the Mf point is that it has been experimentally confirmed that the warp amount is sufficiently reduced in this range (Patent Document 1). Paragraphs [0018], [0019], see FIG. 2, FIG. 4).

At that time, the distance d (mm) from the cooling start position (the lower end of the movable masking 3) to the restraining roll 5 is the passing speed v (mm / s), the plate thickness t (mm) of the metal plate 1, and the quenching start. It is preferable to set the temperature T ₁ (° C.), the target temperature T ₂ (° C.) of the metal plate 1 when passing through the constraining roll 5, and the cooling rate CV (° C./s) of the metal plate 1.

Incidentally, the quenching start temperature _{T 1} (° C.), the temperature of the metal plate 1 at the cooling start position (the lower end of the movable masking 3), constraining rolls 5 during passage temperature _{T 2} (° C.) _is, (T Ms +150 ) (° C) to ( _TMf- 150) (° C).

Here, since the relationship of the following expression (1) is established between the above values, the distance d (mm) is expressed by the following expression (2).
CV = (T ₁ −T ₂ ) / (d / v) (1)
d = (T ₁ −T ₂ ) v / CV (2)

The cooling rate CV is a constant α determined according to cooling conditions (nozzle shape, type of cooling fluid to be injected (here, water 2a) / temperature, injection amount, etc.), and a plate thickness t of the metal plate 1. Can be expressed by using, and since it is almost inversely proportional to the plate thickness t, it can be expressed by the following equation (3).
CV = α / t (3)

For example, for a steel plate having a plate thickness t = 1 to 2 mm, it is represented by the following formula (4), and if the intermediate value is taken, it is represented by the following formula (5) (see paragraph [0022] of Patent Document 1).
CV = 1000 / t to 2000 / t (° C./s) (4)
CV = 1500 / t (° C / s) (5)

That is, in this case, α is the following formula (6) or formula (7).
α = 1000 to 2000 (° C · mm / s) (6)
α = 1500 (℃ ・ mm / s) (7)

From this, the above equation (2) can be expressed by the following equation (8).
d = (T ₁ −T ₂ ) vt / α (8)

  The cooling rate CV (° C / s) and α (° C · mm / s) may be obtained in advance by experiments, numerical analysis, etc., and made into a database or calculation formula.

[Embodiment 2]
FIG. 2 is a diagram showing a quenching and quenching device 12 according to a second embodiment of the present invention.

  As shown in FIG. 2, the quenching and quenching device 12 according to the second embodiment has the same basic configuration as the quenching and quenching device 11 according to the first embodiment, but in addition to that, the movable masking 3 is , An air ejection nozzle 7 for ejecting the air 7a.

  This prevents the water 2a on the metal plate 1 from flowing back to the position of the movable masking 3.

  The first and second embodiments described above can be applied to the production of a metal plate product (metal plate shipped as a product), and particularly preferably to the production of a high-strength cold-rolled steel plate (high tensile strength steel sheet). More specifically, it is preferably applied to the production of 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.

  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.

  Further, not only high-strength cold-rolled steel sheet, but also applied to the production of hot-dip galvanized steel sheet and alloyed hot-dip galvanized steel sheet are similarly preferable.

  In this way, in Embodiments 1 and 2, it becomes possible to control the position where the metal plate 1 reaches the optimum temperature during the quenching and quenching, and it is possible to control the position where the metal plate 1 is manufactured (for example, the plate passing speed v). Therefore, the constraining roll 5 can always suppress the defective shape of the metal plate 1. As a result, in the continuous annealing equipment, it becomes possible to suppress the variation in shape due to the manufacturing conditions of the metal plate 1 that occurs during quenching and quenching.

  In addition, in the above-mentioned Embodiments 1 and 2, the case of quenching and quenching a steel plate with water was described in mind, but the present invention can be applied to the cooling of all metal plates other than the steel plate, and also other than water. It can also be applied to quenching and quenching using a refrigerant.

In the first and second embodiments described above, the temperature T ₂ of the metal plate 1 when passing through the constraining roll 5 is controlled by controlling the distance d from the cooling start position to the constraining roll 5 using the movable masking 3. The shape of the metal plate 1 is kept good regardless of the manufacturing conditions by setting the temperature to T _Ms +150) (° C) to (T _Mf -150) (° C), but the flexibility of processing and operation in the post process is secured. In view of the above, regardless of whether the shape of the metal plate 1 (for example, the amount of warp) is good or defective, if there is no variation in the shape of the metal plate 1 (for example, the amount of warp), the restraint roll 5 passes through. the temperature _{T 2} of the metal plate 1 when _(T Ms _{+150) (℃)} may not be limited to ~ (T Mf -150) (℃ ). The temperature T ₂ is set in advance in consideration of the predicted shape (for example, the amount of warpage) while keeping in mind the degree of freedom of processing and operation in the subsequent process, and the movable masking 3 is used. By controlling the distance d from the cooling start position to the restraint roll 5 so that the temperature of the metal plate 1 when passing through the restraint roll 5 becomes a predetermined temperature T ₂ , the shape of the metal plate 1 (for example, warpage) The amount may be about the same (for example, the variation in the amount of warpage defined in FIG. 7 described later is within 4 mm).

  Examples of the present invention will be described.

As an example of the present invention, a high-strength cold-rolled steel sheet having a plate thickness t of 1.0 mm and a plate width of 1000 mm and a tensile strength of 1470 MPa class is passed through the quenching and quenching apparatus 11 according to the first embodiment of the present invention. The plate speed v was set to 1000 to 3000 mm / s, the quenching start temperature T ₁ was set to 800 ° C., and the target temperature T ₂ when passing through the constraining rolls was set to 400 ° C. The water temperature was 30 ° C., and the cooling rate α / t was set to 1500 / t (° C./s) based on the preliminary measurement and the equation (5).

The temperature T _{Ms at} the Ms point of the high-strength cold-rolled steel sheet is 350 ° C., and the temperature T _{Mf at the} Mf point is 250 ° C. Therefore, as described above, the temperature T ₂ when passing through the constraining rolls may be set in the range of 500 ° C. to 100 ° C., so here, it is set to 400 ° C. as described above.

  Then, the distance d (mm) from the cooling start position to the restraining roll 5 was controlled at d = 267 to 800 mm based on the above equation (8).

  On the other hand, as a comparative example, the quenching and quenching apparatus shown in Patent Document 1 was used, and the other conditions were the same as those of the example of the present invention, and the above high-tensile cold-rolled steel sheet was manufactured.

  However, the quenching and quenching device shown in Patent Document 1 cannot control the distance d (mm) from the cooling start position to the restraining roll, so that d = 400 mm is kept constant.

Then, in each case (the present invention example and the comparative example), the relationship between the strip passing speed v (mm / s) and the temperature T ₂ (° C.) when passing through the restraining roll, and the strip passing speed v (mm / s) And the relationship between the amount of warpage of the steel sheet after cooling was investigated. The definition of the warp amount is shown in FIG. Specifically, the height of the highest position when the steel plate was placed on a horizontal plane was defined as the amount of warpage.

  The results of the example of the present invention are shown in FIGS. 3 and 4, and the results of the comparative example are shown in FIGS.

First, in the comparative example, as shown in FIG. 5, the temperature T ₂ (° C.) when passing through the constraining roll was greatly changed by the passing speed v (mm / s) and could not be controlled. Therefore, under conditions other than v = 1500 mm / s, the temperature T ₂ (° C.) when passing through the constraining roll was outside the range of 500 ° C. to 100 ° C. As a result, as shown in FIG. 6, under conditions other than v = 1500 mm / s, the warpage amount of the steel sheet was all 10 mm or more, and the deformation suppressing effect was insufficient. As a result, the variation in the amount of warpage (difference between the maximum value and the minimum value) was as large as 8 mm.

On the other hand, in the example of the present invention, as shown in FIG. 3, the temperature T ₂ (° C.) when passing through the constraining roll is in the range of 400 ± 20 ° C., regardless of the steel sheet passing condition v (mm / s) that is a manufacturing condition of the steel plate. It was all controllable with. As a result, as shown in FIG. 4, the warpage amount of the steel sheet was all reduced to 10 mm or less. As a result, the variation in the amount of warpage (difference between the maximum value and the minimum value) was suppressed to 2 mm.

  This confirmed the effectiveness of the present invention.

1 Metal Plate 2 Water Jet Nozzle 2a Water 3 Movable Masking 4 Sink Roll 5 Restraint Roll 6 Shielding Cover 7 Air Jet Nozzle 7a Air 11 Quenching and Quenching Equipment 12 Quenching and Quenching Equipment

Claims (11)

A quenching quenching device for cooling a metal plate while continuously passing it,
A cooling fluid ejecting device comprising a plurality of nozzles for ejecting a cooling fluid to the metal plate from both sides of the metal plate,
A pair of restraint rolls for restraining the metal plate,
It is provided between the nozzle and a metal plate passage line through which the metal plate passes, and adjusts a cooling start position of the metal plate by the cooling fluid to control a distance from the cooling start position to the restraint roll. A quenching and quenching device, which is equipped with movable masking. When the temperature of the Ms point at which the martensite transformation of the metal plate starts is T _Ms (° C.) and the temperature of the Mf point at which the martensite transformation ends is T _Mf (° C.), the metal plate is (T _Ms +150) The quenching quenching apparatus according to claim 1, wherein the quenching quenching apparatus is configured to pass through the constraining roll at a temperature of (° C) to ( _TMf- 150) (° C).   The quenching quenching apparatus according to claim 1 or 2, wherein the movable masking is provided with an air jet nozzle.   A quenching quenching method of cooling by spraying a cooling fluid from a plurality of nozzles onto the surface of a metal plate that is continuously passed, wherein the metal plate is constrained by a constraining roll, and the cooling fluid is cooled by the movable masking. A quenching and quenching method comprising adjusting a cooling start position of a metal plate and controlling a distance from the cooling start position to the restraining roll. When the temperature of the Ms point at which the martensite transformation of the metal plate starts is T _Ms (° C.) and the temperature of the Mf point at which the martensite transformation ends is T _Mf (° C.), the metal plate is (T _Ms +150) The quenching and quenching method according to claim 4, wherein the constraining roll is passed at a temperature of (° C) to ( _TMf- 150) (° C).   The distance from the cooling start position of the metal plate to the constraining roll is based on the plate passing speed of the metal plate, the quenching start temperature, the temperature of the metal plate when passing through the target constraining roll, and the cooling speed of the metal plate. The quenching and quenching method according to claim 4 or 5, wherein The passing speed of the metal plate is v (mm / s), the quenching start temperature is T ₁ (° C.), the target temperature when passing through the constraining roll is T ₂ (° C.), and the cooling speed of the metal plate is CV ( The quenching and quenching method according to claim 6, wherein a distance d (mm) from the cooling start position of the metal plate to the constraining roll is represented by the following formula as C / s).
d = (T ₁ −T ₂ ) v / CV   The distance from the cooling start position of the metal plate to the constraining roll, the passage speed of the metal plate, the quenching start temperature, the temperature of the metal plate when passing the target constraining roll, the cooling conditions, the plate of the metal plate The quenching and quenching method according to claim 4, wherein the quenching and quenching method is set based on the thickness. The passing speed of the metal plate is v (mm / s), the quenching start temperature is T ₁ (° C.), and the target temperature when passing through the constraining roll is T ₂ (° C.). Mm / s) and the plate thickness t (mm) of the metal plate, the distance d (mm) from the cooling start position of the metal plate to the constraining roll is represented by the following formula. Item 8. A quenching and quenching method according to Item 8.
d = (T ₁ −T ₂ ) vt / α   A method for producing a metal plate product, which comprises performing quench quenching using the quenching quenching method according to any one of claims 4 to 9 when producing a metal plate product.   The method for producing a metal plate product according to claim 10, wherein the metal plate product is any one of a high-strength cold-rolled steel plate, a hot dip galvanized steel plate, and an alloyed hot dip galvanized steel plate.

Images