JP2019090106A - Rapid cooling hardening apparatus and rapid cooling hardening method, and manufacturing method for metal plate product - Google Patents

Abstract

To provide a rapid cooling hardening apparatus and rapid cooling hardening method, which can suppress the fluctuation in shapes due to the manufacturing condition of a metal plate generated in rapid cooling on a continuous annealing arrangement that anneals the metal plate (e.g., steel plate ) while continuously passing through, and provide a manufacturing method for a metal plate product.SOLUTION: A rapid cooling hardening apparatus of the present invention is the rapid cooling hardening apparatus that cools a metal plate while continuously passing through. The rapid cooling hardening apparatus comprises: a cooling fluid injection device provided with a plurality of nozzles that inject cooling fluid to the metal plate from both surface sides of the metal plate; a pair of restraint rollers that restraint the metal plate; and a movable masking that is provided between the nozzles and a metal plate conveying line where the metal plate passes through, and adjusts a cooling starting position of the metal plate with the cooling fluid to control the distance from the above cooling starting position to the restraint rollers.SELECTED DRAWING: Figure 1

Description

  The present invention relates to a quenching and quenching apparatus, a quenching and quenching method, and a metal sheet product, capable of suppressing variation in shape generated on a metal plate at the time of quenching and quenching in a continuous annealing facility for annealing while continuously passing a metal plate. The manufacturing method of

  In the production of metal plates including steel plates (metal plate products), the metal plates are heated and then cooled to cause a phase transformation, etc., in a continuous annealing facility that performs annealing while continuously passing the metal plates. Work to make the

  In recent years, in the automobile industry, the demand for thin-walled high-tensile steel sheets (high ten) has been increasing for the purpose of achieving both weight reduction of the vehicle body and collision safety. At the time of manufacture of high-tensile steel sheet, a technology for rapidly cooling the steel sheet is important. Water quenching is known as one of the techniques with the fastest cooling rate of steel plates. In the water quenching method, rapid quenching of the steel plate is performed by immersing the heated steel plate in water and simultaneously injecting cooling water onto the steel plate by a quench nozzle provided in the water. At the time of rapid quenching of the steel plate, there is a problem that shape defects such as warpage and wave deformation occur in the steel plate. In order to prevent such a shape defect at the time of rapid cooling of such a steel plate, various methods have been proposed conventionally.

For example, in Patent Document 1, assuming that the temperature at the Ms point at which martensitic transformation of the metal plate starts is T _Ms (° C.) and the temperature at the Mf point at which martensitic transformation ends is T _Mf (° C.) 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 is thermally shrunk by being quenched by the cooling liquid, but in particular, in the metal plate, the martensitic transformation ends from the Ms point, which is the temperature at which the temperature of the metallic plate starts martensitic transformation. 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) (℃ In the range of T) to (T _Mf- 150) (° C.), a restraining roll for restraining the metal plate is disposed. The reason for setting the position of the restraining roll in the range of the Ms point to the Mf point ± 150 ° C. is that in the experiment, it was confirmed that the amount of warpage was sufficiently reduced in this range (paragraph of Patent Document 1) [0018], [0019], see Figures 2 and 4).

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

Patent No. 6094722 Japanese Patent Application Laid-Open No. 60-194022

However, in the method described in Patent Document 1, although it is possible to prevent certainly deformation of the metal plate during quenching quenching, the manufacturing conditions of the metal plate, the temperature of the metal sheet _{(T Ms +150) (℃)} ~ (T _The position of the metal plate changes in the range of ( _{M f −} 150) (° C.), so that the constraining roll sets the metal plate at a position where the temperature of the metal plate becomes (T _Ms + 150) (° C.) to (T _{M f −} 150) (° C.) In some cases, it is not possible to restrain, and a constraining roll can not always be effective. As a result, variations occur in the shape of the metal plate depending on the manufacturing conditions of the metal plate, and there is a problem that the processing and the like in the subsequent steps become complicated.

  Further, in the method described in Patent Document 2, although the control of the cooling stop temperature can be performed, there is a problem that the control of the cooling start position can not be performed.

  The present invention has been made to solve such problems, and in a continuous annealing system for performing annealing while continuously passing a metal plate (for example, steel plate), the metal plate generated at the time of 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 of producing a metal sheet product, which can suppress shape variations due to the production conditions of

  The present inventors earnestly studied to solve such a problem, and as a result, they obtained the following findings and ideas.

  That is, in the rapid quenching of a metal plate (for example, a steel plate), the temperature of the metal plate is lowered 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. In addition, in quenching and quenching of a metal plate, it is not necessary to immerse the metal plate in water, and if a sufficient amount of water is jetted from a nozzle, a cooling capacity equivalent to jetting in water can be obtained.

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

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

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

  [3] The quench and quench apparatus according to the above [1] or [2], wherein the movable masking is provided with an air jet nozzle.

  [4] A quenching and quenching method of cooling by injecting a cooling fluid from a plurality of nozzles onto the surface of a metal plate which is continuously passed through, wherein the cooling is performed by movable masking while the metal plate is restrained by a restraining roll. A quenching and hardening 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 restraining roll.

[5] The temperature of the Ms point at which martensitic transformation of the metal plate starts is T _Ms (° C.), and the temperature of Mf point at which martensitic transformation ends is T _Mf (° C.) The quenching and quenching method according to [4], wherein the constraining 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, the passing speed of the metal plate, the quenching start temperature, the temperature of the metal plate at the time of passing the constraining roll to be targeted, the cooling of the metal plate The quenching and hardening method according to the above [4] or [5], which is set based on the speed.

[7] The passing speed of the metal plate is v (mm / s), the quenching start temperature is T ₁ (° C.), the temperature at the time of passing the constraining roll to be targeted is T ₂ (° C.), the cooling rate of the metal plate The distance d (mm) from the cooling start position of the metal plate to the constraining roll is expressed by the following equation, where CV (° C./s) is CV (° C./s).
d = (T _1- T ₂ ) v / CV

  [8] The distance from the cooling start position of the metal plate to the constraining roll, the passing speed of the metal plate, the quenching start temperature, the temperature of the metal plate at the time of passing the constraining roll to be targeted, cooling conditions, the metal The quenching and hardening method according to the above [4] or [5], which is set based on the thickness of the plate.

[9] The constant is determined by the cooling conditions, where the passing speed of the metal plate is v (mm / s), the quenching start temperature is T ₁ (° C.), and the temperature at the time when the target constraining roller passes is T ₂ (° C.) The distance d (mm) from the cooling start position of the metal plate to the restraining roll is expressed by the following equation using α (° C. mm / s) and the plate thickness t (mm) of the metal plate The quenching method according to the above [8].
d = (T ₁ −T ₂ ) vt / α

  [10] A method for producing a metal sheet product, characterized in that when the metal sheet product is produced, quenching is carried out using the quenching method according to any one of the above [4] to [9].

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

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

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

  Embodiments of the present invention will be described based on the drawings.

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

  As shown in FIG. 1, the quenching and quenching apparatus 11 according to this embodiment 1 is a water 2a which is a refrigerant (cooling fluid) from the both sides of a metal plate (for example, steel plate) 1 passing continuously to the metal plate 1 Between a plurality of water jet nozzles 2 (cooling fluid jet apparatus) that jets and rapidly cools, and a metal plate passing line through which the water jet nozzles 2 and the metal plate 1 pass, A movable masking 3 for adjusting the cooling start position 1 and a pair of restraining rolls 5 for restraining the metal plate 1 to prevent deformation are provided. Moreover, in order to prevent the water 2a jetted from the water jet nozzle 2 from scattering around the quenching and quenching device 11, a shielding cover 6 is provided. Further, on the outlet side of the restraining roll 5, a sink roll 4 for changing the transport direction (sheet passing direction) of the metal plate 1 is provided.

By this, in this Embodiment 1, when performing the quenching and quenching method which cools by injecting water 2a from the plurality of water jet nozzles 2 onto the surface of the metal plate 1, the martensitic transformation of the metal plate 1 starts Ms _Assuming that the temperature of the point is T _Ms (° C.) and the temperature of the Mf point where martensitic transformation ends is T _Mf (° C.), the metal by the cooling fluid is held by the movable masking 3 while the metal plate 1 is restrained by the restraint roll 5 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 made to pass.

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 Although metal plate 1 is thermally shrunk by being quenched by the cooling liquid as it is, in particular, in metal plate 1, the temperature of metal plate 1 is martensitic from the Ms point at which the martensitic transformation starts. When the temperature reaches Mf point where transformation ends, rapid thermal contraction and transformation expansion simultaneously occur, the stress acting in the metal plate 1 becomes the largest, and the shape collapses, so the temperature of the metal plate 1 ( In the range of T _Ms +150) (° C.) to (T _Mf −150) (° C.), the metal plate 1 is passed while being restrained by the restraining roll 5. The reason for setting the position of the constraining roll 5 in the range of the Ms point to the Mf point ± 150 ° C. is that in the experiment, it has been confirmed that the amount of warpage is sufficiently reduced in this range (Patent Document 1) Paragraphs [0018], [0019], see FIGS. 2 and 4).

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

Incidentally, the hardening start temperature T ₁ (° C.) is the temperature of the metal plate 1 at the cooling start position (lower end of the movable masking 3), and the temperature T ₂ (° C.) when passing through the restraining roll 5 is (T _Ms + 150 C.) to ( _T.sub.Mf- 150) (.degree. C.).

Here, since the relationship of the following equation (1) holds between the above values, the distance d (mm) is expressed by the following equation (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 the cooling conditions (nozzle shape, type of cooling fluid to be jetted (here, water 2a), temperature, jet amount, etc.), and the plate thickness t of the metal plate 1 Since it is approximately in inverse proportion to the plate thickness t, it can be represented by the following equation (3).
CV = α / t (3)

For example, in the case of a steel plate having a thickness t of 1 to 2 mm, it is represented by the following equation (4), and the intermediate value is represented by the following equation (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 equation (6) or (7).
α = 1000 to 2000 (° C. mm / s) (6)
α = 1500 (° C. 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 rates CV (° C./s) and α (° C. mm / s) may be obtained in advance by experiments or numerical analysis, and may be made into a database or a formula.

Second Embodiment
FIG. 2 is a view showing a rapid quenching apparatus 12 according to a second embodiment of the present invention.

  As shown in FIG. 2, the quenching and quenching apparatus 12 according to the second embodiment has the same basic configuration as the quenching and quenching apparatus 11 according to the above-described first embodiment, but in addition to that, the movable masking 3 is , And an air jet nozzle 7 for jetting the air 7a.

  Thus, the backflow of the water 2 a on the metal plate 1 to the position of the movable masking 3 is prevented.

  And said Embodiment 1, 2 is applicable to manufacture of a metal plate product (metal plate shipped as a product), and it is especially preferable to apply to manufacture of a high strength cold rolled steel plate (high ten). More specifically, it is preferable to apply to manufacture of the steel plate which is 580 Mpa or more in tensile strength. The upper limit of the tensile strength is not particularly limited, but may be, for example, 1600 MPa or less.

  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, Mn is 0.80% or more 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 at least one or more of Cr, Mo, Nb, V, Ni, Cu, and Ti is 0.5% or less as needed , B and Sb are each 0.01% or less, and the balance is Fe and unavoidable impurities.

  Moreover, it is equally preferable to apply not only to the high strength cold rolled steel sheet but also to the production of a hot-dip galvanized steel sheet or an alloyed hot-dip galvanized steel sheet.

  In this manner, in the first and second embodiments, it is possible to control the position at which the metal plate 1 reaches the optimum temperature at the time of quenching and quenching, and the manufacturing conditions of the metal plate 1 (for example, sheet passing speed v) Therefore, it is always possible to suppress the shape defect generated in the metal plate 1 by the constraining roll 5. As a result, in the continuous annealing equipment, it is possible to suppress the variation in the shape due to the manufacturing conditions of the metal plate 1 which occurs at the time of rapid quenching.

  In the first and second embodiments described above, the case where the steel plate is quenched and quenched with water is described in mind, but the present invention can be applied to cooling of all metal plates other than steel plates, and it is also possible to use other than water. The present invention can also be applied to quenching and quenching using a refrigerant.

In the first and second embodiments described above, the movable masking 3 is used to control the distance d from the cooling start position to the restraining roll 5 so that the temperature T ₂ of the metal plate 1 when the restraining roll 5 passes ( The shape of the metal plate 1 is kept good regardless of the manufacturing conditions by setting T _Ms +150) (° C.) to (T _Mf- 150) (° C.), but securing the freedom of processing and operation in the post process From the point of, etc., regardless of whether the shape (for example, the amount of warpage) of the metal plate 1 is good or defective, if it is sufficient that there is no variation in the shape (for example, the amount of warpage) of the metal plate 1, the temperature _{T 2} of the metal plate 1 when _(T Ms _{+150) (℃)} may not be limited to ~ (T Mf -150) (℃ ). Using the movable masking 3, the temperature T ₂ is determined in advance in consideration of the predicted shape (for example, the amount of warpage) with the processing in the post-process and securing of the freedom of operation in mind. by controlling the distance d to the constraining rolls 5 from the cooling start position, so as to be temperature T ₂ the temperature of the constraining rolls 5 when passing the metal plate 1 is predetermined, the shape of the metal plate 1 (e.g., warpage The amount may be made to be the same (for example, the variation of the amount of warpage defined in FIG. 7 described later is within 4 mm).

  An embodiment of the present invention will be described.

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

The temperature T _{Ms at} the Ms point of the high-tensile cold rolled steel sheet is 350 ° C., and the temperature T _{Mf at the} Mf point is 250 ° C. Therefore, as described above, since the temperature T2 at the time of passing through the constraining roll may be set in the range of 500 ° C. to 100 ° C., the temperature T ₂ is set to 400 ° C. as described above.

  And the distance d (mm) from the cooling start position to the restraining roll 5 was controlled by d = 267-800 mm based on said Formula (8).

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

  However, since the quenching and quenching apparatus shown in Patent Document 1 can not control the distance d (mm) from the cooling start position to the restraining roll, d is constant at 400 mm.

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

  The result of the example of the present invention is shown in FIG. 3 and FIG. 4, and the result of the comparative example is shown in FIG. 5 and FIG.

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

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

  This confirms the effectiveness of the present invention.

DESCRIPTION OF SYMBOLS 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 Rapid-hardening apparatus 12 Rapid-quenching apparatus

Claims (11)

A quenching and quenching apparatus for cooling while continuously passing a metal plate,
A cooling fluid injection device comprising a plurality of nozzles for injecting a cooling fluid from both sides of the metal plate to the metal plate;
A pair of restraining rolls for restraining the metal plate;
It is provided between the nozzle and the metal plate passing line through which the metal plate passes, and adjusts the cooling start position of the metal plate by the cooling fluid to control the distance from the cooling start position to the restraining roll. And a movable masking. The temperature of the Ms point where martensitic transformation of the metal plate starts is T _Ms (° C.), and the temperature of Mf point where martensitic transformation ends is T _Mf (° C.), the metal plate is (T _Ms + 150) The quenching and quenching apparatus according to claim 1, wherein the constraining roll is passed at a temperature of (° C) to ( _TMf- 150) (° C).   The said movable masking is provided with an air injection | spray nozzle, The quench hardening apparatus of Claim 1 or 2 characterized by the above-mentioned.   A quenching method for cooling by injecting a cooling fluid from a plurality of nozzles onto a surface of a metal plate which is continuously passed through, wherein the metal plate is restrained by a restraining roll and the movable fluid is masked by the cooling fluid. A quenching method characterized in that a cooling start position of a metal plate is adjusted to control a distance from the cooling start position to the restraining roll. The temperature of the Ms point where martensitic transformation of the metal plate starts is T _Ms (° C.), and the temperature of Mf point where martensitic 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 sheet passing speed of the metal plate, the quenching start temperature, the temperature of the metal plate at the time of passing the constraining roll to be targeted, and the cooling rate of the metal plate. The quenching and hardening method according to claim 4 or 5, characterized in that: The passing speed of the metal plate is v (mm / s), the quenching start temperature is T ₁ (° C.), the temperature at the time of passing the constraining roll to be targeted is T ₂ (° C.), and the cooling rate of the metal plate is CV (CV) The quenching and quenching method according to claim 6, wherein the distance d (mm) from the cooling start position of the metal plate to the constraining roll is expressed by the following equation 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 is defined as the sheet passing speed of the metal plate, the quenching start temperature, the temperature of the metal plate at the time of passing the constraining roll to be targeted, cooling conditions, the plate of the metal plate The quenching and hardening method according to claim 4 or 5, wherein the setting is performed 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 temperature at the time when the target constraining roller passes is T ₂ (° C.). The distance d (mm) from the cooling start position of the metal plate to the constraining roll is expressed by the following equation using mm / s) and the plate thickness t (mm) of the metal plate. 9. The quenching and quenching method according to item 8.
d = (T ₁ −T ₂ ) vt / α   The manufacturing method of a metal plate product characterized by performing quenching and quenching using a rapid-quenching method in any one of Claims 4-9, when manufacturing a metal plate product.   The method of manufacturing a metal sheet product according to claim 10, wherein the metal sheet product is any one of a high strength cold rolled steel sheet, a hot-dip galvanized steel sheet, and an alloyed hot-dip galvanized steel sheet.

Images