JP7384296B2 - Dehydrogenation equipment, steel plate manufacturing system, and steel plate manufacturing method - Google Patents

Description

The present invention relates to a dehydrogenation device and a steel sheet manufacturing system for manufacturing steel sheets suitable as members used in industrial fields such as automobiles, home appliances, and building materials. In particular, the present invention relates to a dehydrogenation device and a steel plate production system for obtaining a steel plate with a small amount of diffusible hydrogen inherent in the steel and excellent resistance to hydrogen embrittlement, and a steel plate production method.

It is known that a particular concern with high-strength steel sheets is that the steel sheets become brittle due to hydrogen penetrating the steel sheets (hydrogen embrittlement). When a steel sheet is annealed using a continuous annealing device and a continuous hot-dip galvanizing device, a H ₂ —N ₂ mixed gas, which is often used as a reducing or non-oxidizing gas, is introduced into the annealing furnace. Due to the annealing in the H ₂ -N ₂ gas mixture, hydrogen penetrates into the steel. Furthermore, in steel sheets for automobiles, hydrogen is generated due to the corrosion reaction that progresses in the environment in which the automobile is used, and enters into the steel. If the diffusible hydrogen that has entered the steel is not sufficiently reduced, there is a risk that the steel sheet will become hydrogen embrittled due to the diffusible hydrogen, resulting in delayed fracture.

Conventionally, various studies have been made on methods of reducing the amount of diffusible hydrogen in steel. For example, Patent Document 1 discloses a method of reducing the amount of hydrogen trapped in steel by performing aging treatment after annealing treatment and elongation rolling. Furthermore, as a method for reducing diffusible hydrogen, a method is known in which a steel plate after annealing is left at room temperature for a long time to desorb diffusible hydrogen from the surface of the steel plate. Patent Document 2 discloses a method of reducing the amount of diffusible hydrogen in steel by holding a cold-rolled and then annealed steel plate within a temperature range of 50°C or more and 300°C or less for 1800 seconds or more and 3200 seconds or less. ing.

Patent No. 6562180 International Publication No. 2019/188642

However, in the methods described in Patent Documents 1 and 2, it is difficult to apply the methods described in Patent Documents 1 and 2 to other steel sheets because there is a risk that structural changes may occur due to heating and holding after annealing. Met. Furthermore, in the method of leaving the steel plate at room temperature, it is necessary to leave the steel plate for a long time, resulting in low productivity.

The present invention has been made in view of the above circumstances, and includes a steel plate dehydrogenation device and a steel plate manufacturing apparatus that can produce a steel plate with excellent hydrogen embrittlement resistance without changing the mechanical properties of the steel plate. The purpose of the present invention is to provide a system and a method for manufacturing steel sheets.

In order to achieve the above-mentioned problem, the inventors of the present invention have conducted extensive studies and found that by applying vibrations of a predetermined frequency and maximum amplitude to a steel plate, the amount of diffusible hydrogen in the steel can be reduced. We found that hydrogen embrittlement can be suppressed by using hydrogen embrittlement. Specifically, it has been found that hydrogen in the steel plate can be sufficiently and efficiently reduced by slightly vibrating the steel plate at a high frequency and a small maximum amplitude. This is presumed to be due to the following mechanism. By forcibly vibrating the steel plate, the steel plate is repeatedly subjected to bending deformation. As a result, the lattice spacing on the surface is expanded compared to the center of the thickness of the steel plate. Hydrogen in the steel sheet diffuses toward the surface of the steel sheet, which has a wide lattice spacing and low potential energy, and is desorbed from the surface.

The present invention has been made based on the above findings. That is, the gist of the present invention is as follows.

[1] A housing section that houses a steel plate coil obtained by winding a steel strip into a coil shape;
A vibration adding device that applies vibration to the steel plate coil housed in the housing part so that the frequency of vibration of the steel plate coil is 100 to 100,000 Hz, and the maximum amplitude of the steel plate coil is 10 nm to 500 μm. and,
A dehydrogenation device with

[2] The vibration adding device includes an electromagnet having a magnetic pole face spaced apart from and facing the surface of the steel plate coil, and is configured such that the steel plate coil vibrates due to an external force applied by the electromagnet to the steel plate coil. , the dehydrogenation apparatus according to [1] above.

[3] The dehydrogenation device according to [1], wherein the vibration applying device has a vibrator that contacts the steel plate coil, and is configured so that the steel plate coil vibrates with the vibrator.

[4] The dehydrogenation device according to any one of [1] to [3], further including a heating section for applying the vibration while heating the steel plate coil.

[5] A dispensing device for dispensing a steel strip from a steel plate coil;
A threading device for threading the steel strip;
a winding device that winds up the steel strip;
Vibration is applied to the steel strip being passed through the sheet threading device so that the frequency of vibration of the steel strip is 100 to 100,000 Hz and the maximum amplitude of the steel strip is 10 nm to 500 μm. additional equipment;
A dehydrogenation device with

[6] The vibration adding device has an electromagnet having a magnetic pole face spaced apart from and facing the surface of the steel strip during threading, and causes the steel strip to vibrate due to an external force applied by the electromagnet to the steel strip. The dehydrogenation apparatus according to the above [5], which is configured as follows.

[7] The dehydrogenation device according to [5], wherein the vibration applying device has a vibrator that contacts the steel strip during threading, and is configured so that the steel strip vibrates with the vibrator. Device.

[8] The dehydrogenation device according to any one of [5] to [7], further comprising a heating section for applying the vibration while heating the steel strip.

[9] The dehydrogenation device according to any one of [1] to [8], further comprising a vibration damping portion that prevents the vibration from being transmitted to the outside of the dehydrogenation device.

[10] A hot rolling device that hot-rolls a steel slab to produce a hot-rolled steel plate;
a hot-rolled steel sheet winding device that winds up the hot-rolled steel sheet to obtain a hot-rolled coil;
The dehydrogenation device according to any one of [1] to [9], wherein the hot rolled coil is the steel plate coil;
A steel sheet manufacturing system with

[11] A cold rolling device that cold-rolls a hot-rolled steel plate to produce a cold-rolled steel plate;
a cold-rolled steel sheet winding device that winds up the cold-rolled steel sheet to obtain a cold-rolled coil;
The dehydrogenation device according to any one of [1] to [9], wherein the cold-rolled coil is the steel plate coil;
A steel sheet manufacturing system with

[12] A batch annealing furnace that performs batch annealing on a cold-rolled coil or a hot-rolled coil to obtain an annealed coil;
The dehydrogenation device according to any one of [1] to [9], wherein the annealed coil is the steel plate coil;
A steel sheet manufacturing system with

[13] A pre-annealing payout device that pays out a cold rolled steel plate or a hot rolled steel plate from a cold rolled coil or a hot rolled coil, respectively;
a continuous annealing furnace that continuously anneals the cold-rolled steel plate or hot-rolled steel plate to produce an annealed steel plate;
an annealed steel plate winding device that winds up the annealed steel plate to obtain an annealed coil;
The dehydrogenation device according to any one of [1] to [9], wherein the annealed coil is the steel plate coil;
A steel sheet manufacturing system with

[14] A plating device that forms a plating film on the surface of a hot-rolled steel sheet or a cold-rolled steel sheet to obtain a plated steel sheet;
a plated steel plate winding device that winds up the plated steel plate to obtain a plated steel plate coil;
The dehydrogenation device according to any one of [1] to [9], wherein the plated steel coil is the steel plate coil;
A steel sheet manufacturing system with

[15] The steel sheet manufacturing system according to [14] above, wherein the plating device is a hot-dip galvanizing device.

[16] The steel sheet manufacturing system according to [14], wherein the plating device includes a hot-dip galvanizing device and an alloying furnace following the galvanizing device.

[17] The steel plate manufacturing system according to [14] above, wherein the plating device is an electroplating device.

[18] Vibration is applied to a steel plate coil obtained by winding a steel strip into a coil shape so that the frequency of vibration of the steel plate coil is 100 to 100,000 Hz and the maximum amplitude of the steel plate coil is 10 nm to 500 μm. A method for producing a steel sheet, including a vibration adding process to produce a product coil.

[19] The method for manufacturing a steel plate according to [18], wherein the vibration applying step is performed while maintaining the steel plate coil at 300° C. or lower.

[20] A step of discharging the steel strip from the steel sheet coil,
A threading step of threading the steel strip;
a step of winding the steel strip into a product coil;
In the threading step, vibration is applied to the steel strip so that the frequency of vibration of the steel strip is 100 to 100,000 Hz, and the maximum amplitude of the steel strip is 10 nm to 500 μm. A method for manufacturing a steel plate, including a vibration addition process.

[21] The method for manufacturing a steel plate according to [20], wherein the vibration applying step is performed while maintaining the steel strip at 300° C. or lower.

[22] A step of hot rolling a steel slab to produce a hot rolled steel plate;
a step of winding the hot-rolled steel sheet to obtain a hot-rolled coil;
The method for manufacturing a steel plate according to any one of [18] to [21], wherein the hot rolled coil is the steel plate coil.

[23] A step of cold-rolling a hot-rolled steel sheet to obtain a cold-rolled steel sheet;
a step of winding the cold-rolled steel sheet to obtain a cold-rolled coil;
The method for manufacturing a steel plate according to any one of [18] to [21], wherein the cold rolled coil is the steel plate coil.

[24] The method according to any one of [18] to [21], including the step of batch annealing a cold-rolled coil or a hot-rolled coil to obtain an annealed coil, wherein the annealed coil is the steel plate coil. Method of manufacturing steel plates.

[25] A step of discharging a cold-rolled steel plate or a hot-rolled steel plate from a cold-rolled coil or a hot-rolled coil, respectively;
Continuously annealing the cold rolled steel plate or the hot rolled steel plate to obtain an annealed steel plate;
Winding the annealed steel plate to obtain an annealed coil;
The method for manufacturing a steel plate according to any one of [18] to [21], wherein the annealed coil is the steel plate coil.

[26] A plating step of forming a plating film on the surface of a hot-rolled steel sheet or a cold-rolled steel sheet to obtain a plated steel sheet;
a step of winding up the plated steel sheet to obtain a plated steel sheet coil;
The method for manufacturing a steel plate according to any one of [18] to [21], wherein the plated steel coil is the steel plate coil.

[27] The method for manufacturing a steel sheet according to [26] above, wherein the plating step includes a hot-dip galvanizing step.

[28] The method for manufacturing a steel sheet according to [26] above, wherein the plating step includes a hot-dip galvanizing step and a subsequent alloying step.

[29] The method for manufacturing a steel plate according to [26] above, wherein the plating step includes an electroplating step.

[30] The method for manufacturing a steel plate according to any one of [18] to [29], wherein the product coil is made of a high-strength steel plate having a tensile strength of 590 MPa or more.

[31] The product coil has a mass percentage of
C: 0.030% or more and 0.800% or less,
Si: 0.01% or more and 3.00% or less,
Mn: 0.01% or more and 10.00% or less,
P: 0.001% or more and 0.100% or less,
S: 0.0001% or more and 0.0200% or less,
[18] to [30] above, comprising a base steel sheet having a composition containing N: 0.0005% or more and 0.0100% or less and Al: 2.000% or less, with the balance consisting of Fe and inevitable impurities. The method for manufacturing a steel plate according to any one of the above.

[32] The component composition further includes, in mass%,
Ti: 0.200% or less,
Nb: 0.200% or less,
V: 0.500% or less,
W: 0.500% or less,
B: 0.0050% or less,
Ni: 1.000% or less,
Cr: 1.000% or less,
Mo: 1.000% or less,
Cu: 1.000% or less,
Sn: 0.200% or less,
Sb: 0.200% or less,
Ta: 0.100% or less,
Ca: 0.0050% or less,
Mg: 0.0050% or less,
The method for producing a steel plate according to [31] above, further containing at least one element selected from the group consisting of Zr: 0.0050% or less and REM: 0.0050% or less.

[33] The product coil has a mass percentage of
C: 0.001% or more and 0.400% or less,
Si: 0.01% or more and 2.00% or less,
Mn: 0.01% or more and 5.00% or less,
P: 0.001% or more and 0.100% or less,
S: 0.0001% or more and 0.0200% or less,
Cr: 9.0% or more and 28.0% or less,
Ni: 0.01% or more and 40.0% or less,
[18] to [30] above, comprising a stainless steel plate having a composition containing N: 0.0005% or more and 0.500% or less and Al: 3.000% or less, with the balance consisting of Fe and inevitable impurities. The method for manufacturing a steel plate according to any one of the above.

[34] The component composition further comprises, in mass%,
Ti: 0.500% or less,
Nb: 0.500% or less,
V: 0.500% or less,
W: 2.000% or less,
B: 0.0050% or less,
Mo: 2.000% or less,
Cu: 3.000% or less,
Sn: 0.500% or less,
Sb: 0.200% or less,
Ta: 0.100% or less,
Ca: 0.0050% or less,
Mg: 0.0050% or less,
The method for producing a steel plate according to [33] above, further containing at least one element selected from the group consisting of Zr: 0.0050% or less and REM: 0.0050% or less.

[35] The method for manufacturing a steel plate according to any one of [18] to [34], wherein the product coil has a diffusible hydrogen amount of 0.50 mass ppm or less.

According to the present invention, a steel plate with excellent hydrogen embrittlement resistance can be manufactured without changing the mechanical properties of the steel plate.

FIG. 2 is a diagram showing an example of the configuration of a vibration adding device. (A) and (B) are diagrams schematically showing an example of how the electromagnet 63 of the vibration adding device 60 is installed with respect to the steel plate coil C in each embodiment of the present invention. (A) and (B) are diagrams schematically showing how a magnetic field is generated from an electromagnet 63 in each embodiment of the present invention. It is a schematic diagram which shows another example of a structure of a vibration adding device. FIG. 2 is a schematic diagram for explaining an example of the configuration of a dehydrogenation device including a vibration applying device 60 according to Embodiment 1, in which (A) is a perspective view of the dehydrogenation device, and (B) is a perspective view of the dehydrogenation device on the side a side. (C) is an example of a view of an example of a dehydrogenation device seen from side b, and (D) is a view of another example of the dehydrogenation device seen from side b. 1 is a schematic diagram for explaining an example of the configuration of a dehydrogenation device including a vibration applying device 70 according to Embodiment 1. FIG. FIG. 3 is a diagram illustrating an example of the configuration of a dehydrogenation device including a vibration applying device 60 according to Embodiment 2, as viewed from the winding axis direction of a steel plate coil. FIG. 3 is a diagram illustrating an example of the configuration of a dehydrogenation device including a vibration applying device 70 according to Embodiment 2, as viewed from the winding axis direction of a steel sheet coil.

Embodiments of the present invention will be described below. The present invention is not limited to the following embodiments. In this specification, a numerical range expressed using "~" means a range that includes the numerical values written before and after "~" as lower and upper limits. In this specification, "steel plate" is a general term that includes hot rolled steel plates, cold rolled steel plates, annealed steel plates obtained by further annealing these steel plates, and plated steel plates with a plating film formed on the surfaces thereof. The shape of the "steel plate" is not limited, and includes both a steel plate coil and a rolled-out steel strip.

This dehydrogenation device applies vibrations of a predetermined frequency and maximum amplitude to a steel plate to reduce the amount of diffusible hydrogen in the steel. According to this dehydrogenation apparatus, since heat treatment on the steel plate is not essential, there is no concern that the structural characteristics of the steel plate will change, and the amount of hydrogen diffused in the steel can be reduced.

Further, in the method for manufacturing the steel plate, vibration is applied so that the frequency of vibration of the steel plate is 100 to 100,000 Hz, and the maximum amplitude of the steel plate is 10 nm to 500 μm. According to the present method for producing a steel sheet, since heat treatment on the steel sheet is not essential, the amount of diffused hydrogen in the steel can be reduced without fear of changing the structural characteristics of the steel sheet.

Although it is not clear why the hydrogen embrittlement resistance of the steel plate can be improved by applying vibration to the steel plate, the present inventors speculate as follows.
That is, vibration is applied to the steel plate under predetermined conditions to forcibly vibrate the steel plate. Due to the bending deformation caused by this forced vibration, the lattice spacing of the steel plate repeats expansion (tension) and contraction (compression) in the thickness direction. Diffusible hydrogen in steel is induced to diffuse toward the tensile side, which has lower potential energy, so the expansion and contraction of this lattice spacing promotes the diffusion of diffusible hydrogen, connecting the inside of the steel sheet and the surface. The diffusion path of diffusible hydrogen is forced. The diffusible hydrogen whose diffusion path has been forcibly formed escapes through the surface to the outside of the steel sheet where it is advantageous in terms of potential energy, at the timing when the lattice spacing near the surface of the steel sheet is expanded. In this way, the vibration applied to the steel plate under predetermined conditions sufficiently and efficiently reduces the diffusible hydrogen in the steel, so it is presumed that hydrogen embrittlement of the steel plate can be effectively and easily suppressed. .

The following describes (1) a dehydrogenation device that applies vibration to a steel plate coil and a method for manufacturing a steel plate, and (2) a dehydrogenation device that applies vibration to the discharged steel plate while unwinding the steel plate coil and rewinding it again. The explanation will be divided into the manufacturing methods of steel sheets.

<Embodiment 1>
The dehydrogenation device according to the present embodiment includes a storage part that stores a steel plate coil C obtained by winding a steel strip into a coil shape, and a frequency of vibration of the steel plate coil with respect to the steel plate coil accommodated in the storage part. This is a dehydrogenation device having a vibration adding device that applies vibrations such that the frequency is 100 to 100,000 Hz and the maximum amplitude of the steel plate coil is 10 nm to 500 μm. In various steps in manufacturing steel sheets, steel strips are wound into steel sheet coils.

Further, in the method for manufacturing a steel plate according to the present embodiment, the frequency of vibration of the steel plate coil is 100 to 100,000 Hz, and the maximum amplitude of the steel plate coil is 100 to 100,000 Hz. A vibration adding step is included in which vibration is applied so that the vibration becomes 10 nm to 500 μm. In various steps in manufacturing steel sheets, steel strips are wound into steel sheet coils.

In the dehydrogenation device and the method for manufacturing a steel plate according to the present embodiment, by applying vibration to the steel plate coil, the amount of diffusible hydrogen in the steel is reduced, and the steel plate has excellent hydrogen embrittlement resistance. can be obtained. In particular, in steel plate coils, since the steel strip is subjected to bending deformation and the lattice spacing on the radially outer surface of the steel strip is expanded, hydrogen diffusion paths are likely to be formed radially outward. it is conceivable that. In this embodiment, by applying vibration to the steel plate coil, a small bending deformation is further applied to the steel strip in a state where the lattice spacing on the radially outer surface is expanded, which is more suitable. Diffusible hydrogen in steel can be reduced.

[[Vibration adding device]]
(Vibration adding device 60)
A vibration adding device can be used to add vibration. In one example, the vibration applying device may be configured to cause the steel plate coil to vibrate due to an external force (attractive force) applied to the steel plate coil by an electromagnet. FIG. 1 shows an example of the configuration of a vibration applying device. In one example, the vibration applying device 60 includes a controller 61, an amplifier 62, an electromagnet 63, a vibration detector 64, and a power source 65. As shown in FIGS. 3A and 3B, in one example, the vibration adding device 60 has an electromagnet 63 including a magnet 63A and a coil 63B wound around the magnet 63A. It has a magnetic pole face 63A1 spaced apart from and facing the surface of the coil. In addition, the "surface of the steel plate coil" here means the surface of the steel plate located at the outermost peripheral part in the radial direction of the steel plate coil C.

The electromagnet 63 has a magnetic pole face 63A1 spaced apart from and facing the surface of the steel plate coil C. It is preferable that the electromagnet 63 has a magnetic pole face 63A1 facing the surface of the steel plate coil C at a distance such that the magnetic pole face 63A1 is perpendicular to the radial direction of the steel plate coil C. Thereby, as shown in FIGS. 3A and 3B, the direction of the magnetic lines of force is along the radial direction of the steel plate coil C, and an attractive force can be exerted on the steel plate coil C. Examples of the shape and installation mode of the electromagnet are shown in FIGS. 2(A) and 2(B).

In FIG. 2(A), rectangular parallelepiped electromagnets 63 extend along the width direction of the steel plate at a predetermined distance from each other on the surface of the steel plate coil C. External force (gravitational force) can be applied uniformly in the width direction, and uniform vibration can be realized in the width direction. By arranging a plurality of such electromagnets 63 along the sheet passing direction, it is possible to sufficiently secure time for applying vibration to the steel plate coil C. As shown in FIG. 2A, the electromagnet 63 includes a magnet 63A and a coil 63B wound around the magnet 63A, and the axial direction of the coil 63B is made to coincide with the thickness direction of the cold rolled steel sheet S. In this case, depending on the direction of the current flowing through the coil 63B, the magnetic pole surface 63A1 facing the steel plate coil C becomes the north pole as shown in FIG. The magnetic pole surface 63A1 facing the steel plate coil C becomes the S pole.

In FIG. 2(B), a plurality of cylindrical electromagnets 63 are arranged at predetermined intervals along the width direction of the steel plate so that the magnetic pole faces at the bottom face the surface of the steel plate coil C at a distance. Therefore, an external force (attractive force) can be uniformly applied to the surface of the steel plate coil C in the width direction, and uniform vibration can be realized in the width direction. By arranging a plurality of rows of such cylindrical electromagnets 63 along the sheet passing direction, sufficient time for applying vibration to the steel plate coil C can be ensured. As shown in FIG. 2(B), each electromagnet 63 has a cylindrical magnet and a coil wound around the cylindrical magnet, and the axial direction of the coil is aligned with the thickness direction of the steel plate coil C. . In this case, depending on the direction of the current flowing through the coil, the magnetic pole surface 63A1 facing the steel sheet coil C becomes the N pole, as shown in FIG. The magnetic pole surface 63A1 facing the coil C becomes the S pole.

In order to apply vibration uniformly to the entire surface of the steel plate coil C, it is preferable that a plurality of electromagnets 63 are arranged at uniform intervals along the circumferential direction of the steel plate coil C. In one example, a plurality of electromagnets 63 may be arranged along the circumferential direction of the steel plate coil C at intervals of 1° to 30° at the central angle of the steel plate coil C.

In the case of FIGS. 3A and 3B, an external force (attractive force) acts on the surface of the steel plate coil C by passing a current through the electromagnet 63. The current flowing through the electromagnet 63 is a direct current pulse current or an alternating current continuous current. When a DC pulse current is passed through the electromagnet 63, an attractive force is intermittently applied to the cold-rolled steel sheet S, causing the steel sheet coil C to vibrate. When a continuous alternating current is passed through the electromagnet 63, each time the direction of the current changes, the magnetic pole surface 63A1 facing the steel plate coil C switches between N and S poles, but the steel plate coil is always subjected to an external force ( gravitational force) works. In the case of alternating current, the magnitude of the external force (gravitational force) acting on the steel plate coil changes as the current value changes over time, so the steel plate coil C vibrates.

The vibration detector 64 shown in FIG. 1 is a laser displacement meter or a laser Doppler vibrometer placed at a predetermined distance from the surface of the steel plate coil C, and measures the frequency and amplitude of vibration on the surface of the steel plate coil C. be able to. By arranging the vibration detector 64 at the same height as the electromagnet 63 in the steel plate coil, the vibration detector 64 can measure the maximum amplitude of vibration of the steel plate coil C. The frequency and maximum amplitude detected by the vibration detector 64 are output to the controller 61. The controller 61 receives the frequency and maximum amplitude values output from the vibration detector 64, compares them with set values, performs PID calculation etc. on the deviation, and controls the cold rolled steel sheet S at a predetermined frequency and maximum amplitude. The frequency (direct current pulse current frequency or alternating current continuous current frequency) and current value of the electromagnet 63 are determined so as to vibrate, and the current value given to the amplifier 62 is determined in consideration of the amplification factor of the amplifier 62. Then, a command value is given to the power supply 65. The power supply 65 is a power supply for passing a current through the coil of the electromagnet 63, receives a command value input from the controller 61, and supplies a current of a predetermined frequency and current value to the amplifier 62. The amplifier 62 amplifies the current value given from the power supply 65 by a predetermined amplification factor, and gives a command value to the electromagnet 63. As a result, a current with a predetermined frequency and current value flows through the electromagnet 63, and the steel plate coil C can be vibrated with a predetermined frequency and maximum amplitude.

(Vibration adding device 70)
In another example, the vibration applying device has a vibrator 72 that contacts the surface of the steel plate coil C, and is configured so that the steel plate coil C is vibrated by the vibrator 72. FIG. 4A shows another example of the configuration of the vibration applying device. Referring to FIG. 4A, vibration adding device 70 includes a controller 71, a vibrator 72, and a vibration detector 73. The vibration adding device 70 has a vibrator 72 that contacts the steel plate coil C, and is configured so that the steel plate coil C is vibrated by the vibrator 72.

The vibrator 72 is not particularly limited as long as it is a general piezoelectric element, and its shape and installation mode are also not limited. For example, as shown in FIG. By bringing the vibrator 72 into surface contact with the surface of the steel plate coil C, the steel plate coil C can be vibrated. In order to apply vibration uniformly to the entire surface of the steel plate coil C, it is preferable that a plurality of vibrators 72 are arranged at uniform intervals along the circumferential direction of the steel plate coil C. In one example, a plurality of vibrators 72 may be arranged along the circumferential direction of the steel plate coil C at intervals of 1° to 30° from each other at the central angle of the steel plate coil C.

The vibration detector 73 shown in FIG. 4A is a laser displacement meter or a laser Doppler vibrometer arranged at a predetermined interval on the surface of the steel plate coil C, and measures the frequency and amplitude of vibration of the steel plate coil C. Can be done. By arranging the vibration detector 73 at the same height position as the vibrator 72 of the steel plate coil C, the maximum amplitude of the vibration of the steel plate coil C can be measured by the vibration detector 73. The frequency and maximum amplitude detected by the vibration detector 73 are output to the controller 71. The controller 71 receives the frequency and maximum amplitude values output from the vibration detector 73, compares them with set values, performs ID calculation on the deviation, and vibrates the steel plate coil C at a predetermined frequency and maximum amplitude. The frequency and current value of the DC pulse current flowing through the vibrator 72 are determined so as to provide the vibrator 72 with a DC pulse current having a predetermined frequency and current value by controlling a power source (not shown). Thereby, the vibrator 72 vibrates at a predetermined frequency and amplitude, and as a result, the steel plate coil C can be vibrated at a predetermined frequency and maximum amplitude.

[[Dehydrogenation equipment]
FIG. 5 shows an example of a dehydrogenation device for reducing diffusible hydrogen in steel by applying vibration to the steel plate coil C by a vibration adding device 60. FIG. 5(A) is a perspective view of the dehydrogenation device 300a. In addition, in FIG. 5(A), only the electromagnets 63 in the nearest row when viewed from the side a side of the dehydrogenation device 300a are shown. FIG. 5(B) is a diagram of the dehydrogenation device 300a viewed from the side a side. As shown in FIGS. 5(A) and 5(B), the dehydrogenation device 300a includes a housing section 80 for housing the steel sheet coil C, and the steel sheet coil C accommodated in the housing section 80 is , an electromagnet 63 that adds vibration. Although the number and arrangement of electromagnets 63 are not particularly limited, in the example of FIG. 2, a plurality of electromagnets 63 are arranged so as to surround the steel plate coil C. Although not shown in FIGS. 5A to 5D, an amplifier 62, a power source 65, and a controller 61 are coupled to each electromagnet 63, and the controller 61 is connected to a vibration A detector 64 is coupled, and vibration is applied to the steel plate coil C from the electromagnet 63. By arranging a plurality of electromagnets 63 so as to surround the steel plate coil C, vibration can be applied uniformly to the steel plate coil C. When the electromagnet 63 is provided so as to surround the steel plate coil C as shown in FIG. 5(A), it is considered that the electromagnet 63 causes the surface of the steel plate coil C to vibrate. In the steel plate coil C whose coil surface is vibrated, the vibration propagates toward the inner circumference of the coil via the air existing between the steel plates in the steel plate coil C, or directly from the vibration of the outermost surface of the coil. It is thought that the vibration propagates toward the inner circumference and eventually reaches the innermost part of the coil. Note that, as illustrated, the housing portion 80 may be capable of housing a plurality of steel plate coils C.

From the viewpoint of applying vibration uniformly to the entire surface of the steel plate coil C, a plurality of electromagnets 63 are arranged along the height direction and width direction of the inner wall of the dehydrogenation device 300a so as to surround the steel plate coil C. It is preferable. FIG. 5(C) shows a diagram of an example of the dehydrogenation device viewed from side b. As shown in FIG. 5C, the electromagnets 63 may be provided at uniform intervals along the height and width directions of the side surface b. Moreover, FIG. 5(D) shows a diagram of another example of the dehydrogenation device viewed from side b. The electromagnet 63 only needs to be able to apply vibration to the steel plate coil C, and may have a rectangular tube shape with a rectangular cross section, for example, as shown in FIG. 5(D). Alternatively, an electromagnet 63 may be placed in a hollow portion defined by the steel plate coil C to apply vibrations from inside the steel plate coil C.

In addition, since diffusible hydrogen is also released from the end face of the steel plate coil C, it is thought that the efficiency of reducing the amount of diffusible hydrogen is lower at the center part of the steel plate coil C in the width direction of the steel plate than at the ends of the steel plate coil C in the width direction of the steel plate. . Therefore, it is particularly preferable that the electromagnet 63 be provided near the center of the steel plate coil C in the width direction of the steel plate.

Note that, as shown in the figure, a coil holding section 90 is appropriately provided in the dehydrogenation device 300a. Although the form of the coil holding part 90 is not particularly limited, when the steel plate coil C is placed so that the winding axis direction of the steel plate coil C is parallel to the floor of the dehydrogenation apparatus 300a, the coil holding part 90 is as shown in FIG. As shown in (A), in order to prevent the steel plate coil C from rolling within the dehydrogenation device 300a, it may be a pair of rod-shaped members that sandwich the steel plate coil C from both sides. The coil holding portion 90 may be a pair of rod-shaped members having a concave arc-shaped upper surface along an arc drawn by the outermost circumference of the steel plate coil C, as shown in FIG. 5(A). Further, although not shown, the steel plate coil C may be placed so that the direction of the winding axis is parallel to the floor of the dehydrogenation apparatus 300a.

From the viewpoint of applying vibration uniformly to the entire surface of the steel plate coil C, a plurality of electromagnets 63 are arranged along the height direction and width direction of the inner wall of the dehydrogenation device 300a so as to surround the steel plate coil C. It is preferable. FIG. 5(C) shows a diagram of an example of the dehydrogenation device viewed from side b. As shown in FIG. 5C, the electromagnets 63 may be provided at uniform intervals along the height and width directions of the side surface b. Moreover, FIG. 5(D) shows a diagram of another example of the dehydrogenation device viewed from side b. The electromagnet 63 only needs to be able to apply vibration to the steel plate coil C, and may have a rectangular tube shape with a rectangular cross section, for example, as shown in FIG. 5(D). Alternatively, an electromagnet 63 may be placed in a hollow portion defined by the steel plate coil C to apply vibrations from inside the steel plate coil C.

In addition, since diffusible hydrogen is also released from the end face of the steel plate coil C, it is thought that the efficiency of reducing the amount of diffusible hydrogen is lower at the center part of the steel plate coil C in the width direction of the steel plate than at the ends of the steel plate coil C in the width direction of the steel plate. . Therefore, it is particularly preferable that the electromagnet 63 be provided near the center of the steel plate coil C in the width direction of the steel plate.

Note that, as shown in the figure, a coil holding section 90 is appropriately provided in the dehydrogenation device 300a. Although the form of the coil holding part 90 is not particularly limited, when the steel plate coil C is placed so that the winding axis direction of the steel plate coil C is parallel to the floor of the dehydrogenation apparatus 300a, the coil holding part 90 is as shown in FIG. As shown in (A), in order to prevent the steel plate coil C from rolling within the dehydrogenation device 300a, it may be a pair of rod-shaped members that sandwich the steel plate coil C from both sides. The coil holding portion 90 may be a pair of rod-shaped members having a concave arc-shaped upper surface along an arc drawn by the outermost circumference of the steel plate coil C, as shown in FIG. 5(A). Further, although not shown, the steel plate coil C may be placed so that the direction of the winding axis is parallel to the floor of the dehydrogenation apparatus 300a.

FIG. 6 shows an example of a dehydrogenation device for reducing diffusible hydrogen in steel by applying vibration to the steel plate coil C by a vibration applying device 70. FIG. 6 is a diagram of the dehydrogenation device 300a viewed from the end surface side of the steel plate coil C. As shown in FIG. 6, the dehydrogenation device 300a includes a housing section 80 for housing the steel sheet coil C, and a vibrator 72 that applies vibration to the steel sheet coil C housed in the housing section 80. The vibrator 72 contacts the steel plate coil C and applies vibration to the steel plate coil C. Although not shown, in each vibration adding device 70, a controller 71 and a vibration detector 73 are coupled to each vibrator 72, and vibration is applied from the vibrator 72 to the steel plate coil C. It has become so. In the dehydrogenation device 300a that applies vibration by the vibration adding device 70, as shown in FIG. It is placed along the surface of the coil C. Although the form for arranging the vibrator 72 along the surface of the steel plate coil C within the dehydrogenation device 300a is not particularly limited, for example, a scaffold may be provided in the accommodation portion 80 so as to cover the surface of the steel plate coil C, and the scaffold may The vibrators 72 can be fixed at regular intervals.

From the viewpoint of uniformly applying vibration to the entire surface of the steel plate coil C, it is preferable to provide the vibrators 72 at regular intervals along the width direction of the steel plate coil C. Alternatively, as shown in FIG. 4(B), it is preferable to use a vibrator 72 extending along the width direction of the steel plate coil C.

In addition, since diffusible hydrogen is also released from the end face of the steel plate coil C, it is thought that the efficiency of reducing the amount of diffusible hydrogen is lower at the center part of the steel plate coil C in the width direction of the steel plate than at the ends of the steel plate coil C in the width direction of the steel plate. . Therefore, it is particularly preferable that the vibrator 72 be provided near the center of the steel plate coil C in the width direction of the steel plate.

Note that, as shown in the figure, a coil holding section 90 is appropriately provided in the dehydrogenation device 300a. Since the details of the coil holding part 90 have been described above, the explanation will be omitted here.

(frequency of vibration)
From the viewpoint of promoting hydrogen diffusion, it is important that the frequency of vibration of the steel plate coil C is 100 Hz or more. When the frequency is less than 100 Hz, the effect of desorbing hydrogen contained in the cold rolled steel sheet S cannot be obtained. From this point of view, the frequency is 100 Hz or more, preferably 500 Hz or more, and more preferably 1000 Hz or more. Note that the steel plate coil C may vibrate unintentionally. However, in these vibrations, the frequency of vibration of the steel plate coil C is about 20 Hz at most, and in this case, the effect of desorbing hydrogen contained in the steel plate coil C cannot be obtained. On the other hand, if the frequency is too high, sufficient time for expanding the lattice spacing within the steel sheet cannot be secured, and the effect of desorbing hydrogen cannot be obtained. From this point of view, it is important that the frequency be 100,000 Hz or less, preferably 80,000 Hz or less, and more preferably 50,000 Hz or less. The frequency of vibration of the steel plate coil C can be measured by the vibration detector 64 shown in FIG. 1 or the vibration detector 73 shown in FIG. 4A. Furthermore, in the case of the vibration adding device 60 shown in FIG. 1, the frequency of vibration of the steel plate coil C can be adjusted by controlling the frequency of the DC pulse current or the frequency of the AC continuous current; In the case of the vibration adding device 70 shown in FIG. 7, the vibration frequency can be adjusted by controlling the vibration frequency of the vibrator 72.

(Maximum amplitude of vibration)
When the maximum amplitude of the steel plate coil C is less than 10 nm, the lattice spacing on the steel plate surface is not sufficiently expanded and hydrogen diffusion is insufficiently promoted, so that the effect of desorbing hydrogen contained in the steel plate coil C is not achieved. I can't do it. Therefore, it is important that the maximum amplitude of the steel plate coil C is 10 nm or more, preferably 100 nm or more, and more preferably 500 nm or more. In addition, if the maximum amplitude of the steel plate coil C exceeds 500 μm, the strain on the steel plate surface increases, causing plastic deformation and trapping hydrogen as a result, so that the hydrogen contained in the steel plate coil C is desorbed. No effect will be obtained. From this point of view, it is important that the maximum amplitude of the steel plate coil C is 500 μm or less, preferably 400 μm or less, and more preferably 300 μm or less. The steel plate coil C vibrates on its own during the threading process, or vibrates when it receives gas from the gas wiping device 32, for example. However, in these vibrations, the maximum amplitude of the steel plate coil C exceeds at least 0.5 mm, so that the effect of desorbing hydrogen contained in the steel plate coil C cannot be obtained. The maximum amplitude of the steel plate coil C can be measured by the vibration detector 64 shown in FIG. 1 or the vibration detector 73 shown in FIG. 4A. Further, the maximum amplitude of the steel plate coil C can be adjusted by controlling the amount of current flowing through the electromagnet 63 in the case of the vibration adding device 60 shown in FIG. 1, and in the case of the vibration adding device 70 shown in FIGS. 4A and B. , can be adjusted by controlling the amplitude of the vibration of the vibrator 72.

(Vibration addition time)
The time period during which vibration is applied to the steel plate coil C is not particularly limited. In this embodiment, vibration is applied to the steel sheet coil after hot rolling or cold rolling, so unlike the case where vibration is applied while passing the steel strip, vibration is applied without restrictions on the irradiation time. can do. Since it is presumed that the longer the vibration is applied, the more diffusible hydrogen can be reduced, the vibration is preferably applied for one minute or more. The duration of vibration is more preferably 30 minutes or longer, and even more preferably 60 minutes or longer. On the other hand, from the viewpoint of productivity, the vibration application time is preferably 30,000 minutes or less, more preferably 10,000 minutes or less, and even more preferably 1,000 minutes or less. The vibration application time can be controlled, for example, by controlling the driving time of the vibration application device 60 by the control unit.

[[Heating device]]
[[Holding temperature of steel plate coil]]
The dehydrogenation device 300a may further include a heating section for applying vibration while heating the steel plate coil C. The temperature of the steel plate coil C in the vibration adding step is not particularly limited. This is because, according to the present embodiment, diffusible hydrogen in the steel can be reduced without heating and holding the steel plate coil C. However, by applying vibration while heating the steel plate coil C by the heating section, the diffusion rate of hydrogen can be further increased, and therefore the amount of diffusible hydrogen in the steel can be further reduced. Therefore, the temperature of the steel plate coil C when applying vibration is preferably 30°C or higher, more preferably 50°C or higher, and even more preferably 100°C or higher. The upper limit of the temperature of the steel plate coil C in the vibration application process is not particularly limited, but from the viewpoint of suitably preventing structural changes in the steel plate coil C, as described later, the upper limit of the temperature of the steel plate coil C is 300°C or less, except when vibration is applied during batch annealing. It is preferable that In this embodiment, the temperature of the steel plate coil C when applying vibration is based on the temperature at the 1/2 position in the radial direction of the steel plate coil. The temperature at the radial 1/2 position of the steel plate coil is measured by directly inserting a thermocouple at the radial 1/2 position of the steel plate coil and measuring the temperature of the steel strip located at the radial 1/2 position. can. The steel plate coil C can be heated by common methods such as installing a heater on the side wall of the housing, or blowing high-temperature air generated externally into the housing 80 and circulating it within the housing. That's fine.

The dehydrogenation device 300a according to the present embodiment may further include a vibration damping portion that prevents the vibration from being transmitted to the outside of the dehydrogenation device 300a. The damping section may be, for example, a damping material provided so as to surround the inner wall of the housing section 80.

According to this embodiment, the amount of diffusible hydrogen in the product coil C obtained after vibration application can be reduced to 0.5 mass ppm or less. By reducing the amount of diffusible hydrogen in the product coil C to 0.5 mass ppm or less, hydrogen embrittlement of the steel plate can be prevented. The amount of diffusible hydrogen in the steel after vibration is applied is preferably 0.3 mass ppm or less, more preferably 0.2 mass ppm or less.

The amount of diffusible hydrogen in the product coil C is measured as follows. A test piece with a length of 30 mm and a width of 5 mm is taken from a half position in the radial direction of the product coil. When the steel sheet is a hot-dip galvanized steel sheet or an alloyed hot-dip galvanized steel sheet, the hot-dip galvanized layer or alloyed hot-dip galvanized layer of the test piece is removed by grinding or alkali. Thereafter, the amount of hydrogen released from the test piece is measured by thermal desorption spectrometry (TDS). Specifically, after continuously heating from room temperature to 300°C at a heating rate of 200°C/h, cooling to room temperature, measuring the cumulative amount of hydrogen released from the test piece from room temperature to 210°C, and determining the product. Let it be the amount of diffusible hydrogen in coil C.

Below, an application example of this embodiment will be described in more detail.

[[Hot rolled steel plate]]
The dehydrogenation device 300a and the method for manufacturing a steel plate according to this embodiment can be applied to manufacturing a hot rolled steel plate.

The steel plate manufacturing system according to this application example includes a hot rolling device that hot-rolls a steel slab to produce a hot-rolled steel plate, and a hot-rolled steel plate winding device that winds up the hot-rolled steel plate to obtain a hot-rolled coil. and a steel sheet dehydrogenation device in which the hot rolled coil is the steel sheet coil C. A hot rolling apparatus hot-rolls a steel slab having a known composition by rough rolling and finish rolling to produce a hot-rolled steel plate. The hot-rolled steel sheet winding device winds up the hot-rolled steel sheet to form a hot-rolled coil. The dehydrogenation device 300a uses the hot-rolled coil as a steel plate coil C and applies vibration to the hot-rolled coil under the above-described conditions. By applying the vibration, the amount of diffusible hydrogen in the steel can be reduced, and a hot rolled steel sheet with excellent hydrogen embrittlement resistance can be obtained. Note that the obtained hot-rolled steel sheet may be further subjected to cold rolling to obtain a cold-rolled steel sheet.

The method for manufacturing a steel plate according to this application example includes the steps of hot rolling a steel slab to obtain a hot rolled steel plate, and winding up the hot rolled steel plate to obtain a hot rolled coil. The coil is the steel plate coil described above. The method for producing a hot rolled coil before applying vibration is not particularly limited, and a steel slab having a known composition is subjected to hot rolling consisting of rough rolling and finish rolling to obtain a hot rolled steel plate, and the hot rolled steel plate is What is necessary is just to wind up according to a well-known method and to make a hot-rolled coil. By applying vibration to the hot-rolled coil under the conditions described above, the amount of diffusible hydrogen in the steel can be reduced, and a hot-rolled steel sheet with excellent hydrogen embrittlement resistance can be obtained. Note that the obtained hot-rolled steel sheet may be further subjected to cold rolling to obtain a cold-rolled steel sheet.

[[Cold rolled steel sheet]]
The dehydrogenation device 300a and the method for manufacturing a steel plate according to the present embodiment can also be applied to manufacturing a cold rolled steel plate.

The steel plate manufacturing system according to this application example includes a cold rolling device that cold-rolls a hot-rolled steel plate to produce a cold-rolled steel plate, and a cold-rolled steel plate winder that winds up the cold-rolled steel plate to obtain a cold-rolled coil. and a dehydrogenation device 300a that uses the cold-rolled coil as the steel sheet coil C. The cold rolling equipment applies or does not perform hot-rolled plate annealing on a known hot-rolled steel plate, and applies one cold rolling process to a hot-rolled steel plate after hot rolling or a hot-rolled steel plate after hot-rolled plate annealing. A cold-rolled steel sheet having a final thickness is obtained by performing cold rolling two or more times with rolling or intermediate annealing in between. A cold-rolled steel sheet winding device winds up a cold-rolled steel sheet after cold rolling into a cold-rolled coil according to a known method. The dehydrogenation device 300a uses the cold-rolled coil as a steel sheet coil C and applies vibration to the cold-rolled coil under the conditions described above. By applying the vibration, the amount of diffusible hydrogen in the steel can be reduced, and a cold rolled steel sheet with excellent hydrogen embrittlement resistance can be obtained. Note that the steel plate manufacturing system may further include a dehydrogenation device 300a that can apply vibration under the above-mentioned conditions to a hot rolled coil obtained by winding up a hot rolled steel plate after hot rolling. . Next, the hot-rolled steel sheet is taken out from the hot-rolled coil after vibration has been applied, and is cold-rolled to form a cold-rolled coil, and further vibration is applied to the cold-rolled coil by the dehydrogenation device 300a, thereby reducing the diffusion in the steel. By further reducing the amount of hydrogen embrittlement, it is possible to obtain a steel sheet with particularly excellent hydrogen embrittlement resistance.

The method for manufacturing a steel plate according to this application example includes a step of cold rolling a hot rolled steel sheet to obtain a cold rolled steel sheet, and a step of winding the cold rolled steel sheet to obtain a cold rolled coil. The coil is the steel plate coil described above. The method of manufacturing the cold rolled coil before applying vibration is not particularly limited. In one example, a steel slab having a known composition is subjected to hot rolling consisting of rough rolling and finish rolling to obtain a hot rolled steel plate, and the hot rolled steel plate is subjected to or without hot rolling annealing, A cold-rolled steel plate having a final thickness obtained by subjecting a hot-rolled steel plate after hot rolling or a hot-rolled steel plate after hot-rolled plate annealing to one cold rolling or two or more cold rollings with intermediate annealing in between. can do. The cold-rolled steel sheet after cold rolling is wound into a cold-rolled coil according to a known method. By applying vibration to the cold-rolled coil under the conditions described above, the amount of diffusible hydrogen in the steel can be reduced, and a cold-rolled steel sheet with excellent hydrogen embrittlement resistance can be obtained. In addition to applying vibration to the cold-rolled coil, the hot-rolled steel sheet after hot rolling was wound up to form a hot-rolled coil, and vibration was also applied to the hot-rolled coil under the conditions described above. You can. Next, the hot-rolled steel sheet is taken out from the hot-rolled coil after vibration has been applied, cold-rolled to form a cold-rolled coil, and further vibration is applied to the cold-rolled coil to reduce the amount of diffusible hydrogen in the steel. By further reducing it, a steel plate with particularly excellent hydrogen embrittlement resistance can be obtained.

In this embodiment, the type of hot-rolled steel plate or cold-rolled steel plate to which vibration is applied is not particularly limited. Although the composition of the steel plate is not particularly limited, a steel plate having the following composition is exemplified as a steel plate to which the embodiment can be particularly suitably applied. First, the appropriate range of the composition of the steel sheet and the reason for its limitation will be explained.

[Essential ingredients]
C: 0.030% or more and 0.800% or less C is an element necessary to increase strength. Particularly suitable strength can be obtained by setting the C content to 0.030% or more. Furthermore, by setting the C content to 0.800% or less, embrittlement of the material itself can be particularly preferably prevented. From this viewpoint, the amount of C is preferably 0.030% or more, and preferably 0.800% or less. The amount of C is more preferably 0.080% or more. Moreover, the amount of C is more preferably 0.500% or less.

Si: 0.01% or more and 3.00% or less,
Si is a solid solution strengthening element that becomes a substitutional solid solution and greatly hardens the material, and is effective for increasing the strength of the steel plate. In order to obtain the effect of increasing strength by adding Si, the amount of Si is preferably 0.01% or more. On the other hand, from the viewpoint of preventing embrittlement and deterioration of ductility of the steel, and further preventing red scale and the like to obtain good surface properties, and in turn, obtaining good plating appearance and plating adhesion, the Si amount is set to 3.00. % or less. Therefore, the content of Si is preferably 0.01% or more, and preferably 3.00% or less. The content of Si is more preferably 0.10% or more, and more preferably 2.50% or less.

Mn: 0.01% or more and 10.00% or less Mn increases the strength of the steel plate by solid solution strengthening. In order to obtain this effect, the amount of Mn is preferably 0.01% or more. On the other hand, by setting the Mn amount to 10.00% or less, Mn segregation can be suitably prevented, unevenness in the steel structure can be prevented, and hydrogen embrittlement can be further suppressed. Therefore, it is preferable that the amount of Mn is 10.00% or less. The amount of Mn is more preferably 0.5% or more, and more preferably 8.00% or less.

P: 0.001% or more and 0.100% or less P is an element that has a solid solution strengthening effect and can be added depending on the desired strength. In order to obtain these effects, it is preferable that the amount of P be 0.001% or more. On the other hand, by controlling the amount of P to 0.100% or less, excellent weldability can be obtained. In addition, by setting the amount of P to 0.100% or less, when forming a galvanized film on the surface of the steel sheet and performing alloying treatment on the galvanized film to form an alloyed galvanized film, the alloying rate can be increased. It is possible to form a galvanized film of excellent quality by preventing the deterioration of the coating. Therefore, the amount of P is preferably 0.001% or more, and preferably 0.100% or less. The amount of P is more preferably 0.003% or more. Further, the amount of P is more preferably 0.050% or less.

S: 0.0001% or more and 0.0200% or less By reducing the amount of S, the embrittlement of steel during hot working is suitably prevented, and the generation of sulfides is suitably prevented to improve local deformability. be able to. Therefore, the amount of S is preferably 0.0200% or less, more preferably 0.0100% or less, and even more preferably 0.0050% or less. Although the lower limit of the amount of S is not particularly limited, due to constraints on production technology, the amount of S is preferably 0.0001% or more, and more preferably 0.0050% or less.

N: 0.0005% or more and 0.0100% or less By reducing the amount of N, the aging resistance of steel can be improved. Therefore, the amount of N is preferably 0.0100% or less, more preferably 0.0070% or less. Although the lower limit of the amount of N is not particularly limited, due to constraints on production technology, the amount of N is preferably 0.0005% or more, more preferably 0.0010% or more.

Al: 2.000% or less Al acts as a deoxidizing agent and is an effective element for improving the cleanliness of steel, and is preferably added in the deoxidizing step. In order to obtain the effect of addition, when added, the amount of Al is preferably 0.001% or more. On the other hand, from the viewpoint of suitably preventing the occurrence of steel billet cracking during continuous casting, the Al content is preferably 2.000% or less. The amount of Al is more preferably 0.010% or more. Further, the amount of Al is more preferably 1.200% or less.

[Optional ingredients]
The component composition is further expressed in mass%: Ti: 0.200% or less, Nb: 0.200% or less, V: 0.500% or less, W: 0.500% or less, B: 0.0050% or less, Ni : 1.000% or less, Cr: 1.000% or less, Mo: 1.000% or less, Cu: 1.000% or less, Sn: 0.200% or less, Sb: 0.200% or less, Ta: 0 .100% or less, Ca: 0.0050% or less, Mg: 0.0050% or less, Zr: 0.0050% or less, and REM: 0.0050% or less. You may.

Ti: 0.200% or less Ti contributes to increasing the strength of the steel sheet by precipitation strengthening of the steel and fine grain strengthening by suppressing the growth of ferrite crystal grains. When adding Ti, it is preferably 0.005% or more. When adding Ti, the amount of Ti is more preferably 0.010% or more. Further, by setting the Ti amount to 0.200% or less, precipitation of carbonitrides can be suitably prevented and formability can be further improved. Therefore, when adding Ti, it is preferable that the amount added is 0.200% or less. The amount of Ti is more preferably 0.100% or less.

Nb: 0.200% or less, V: 0.500% or less, W: 0.500% or less Nb, V, and W are effective for precipitation strengthening of steel. When adding Nb, V, and W, it is preferable that each of them be 0.005% or more. When Nb, V, and W are added, more preferably each of them is 0.010% or more. In addition, by setting Nb to 0.200% or less and V and W to 0.500% or less, the amount of carbonitride precipitation can be suitably prevented similarly to Ti, and formability can be further improved. can. Therefore, when adding Nb, the amount added is preferably 0.200% or less, more preferably 0.100% or less. When V and W are added, their amounts are preferably each 0.500% or less, more preferably each 0.300% or less.

B: 0.0050% or less B is effective in strengthening grain boundaries and increasing the strength of steel sheets. When B is added, it is preferably 0.0003% or more. Further, in order to obtain more suitable moldability, it is preferable that B be 0.0050% or less. Therefore, when B is added, the amount added is preferably 0.0050% or less, more preferably 0.0030% or less.

Ni: 1.000% or less Ni is an element that increases the strength of steel through solid solution strengthening. When adding Ni, it is preferably 0.005% or more. Further, from the viewpoint of further improving ductility by reducing the area ratio of hard martensite, Ni is preferably 1.000% or less. Therefore, when adding Ni, the amount added is preferably 1.000% or less, more preferably 0.500% or less.

Cr: 1.000% or less, Mo: 1.000% or less Cr and Mo have the effect of improving the balance between strength and formability, so they can be added as necessary. When adding Cr and Mo, it is preferable that Cr: 0.005% or more and Mo: 0.005% or more. Moreover, from the viewpoint of reducing the area ratio of hard martensite and further improving ductility, it is preferable that Cr and Mo be 1.000% or less, and 1.000% or less, respectively. It is preferable that Cr and Mo be Cr: 0.500% or less and Mo: 0.500% or less, respectively.

Cu: 1.000% or less Cu is an element effective in strengthening steel, and can be added as necessary. When adding Cu, it is preferably 0.005% or more. In addition, from the viewpoint of reducing the area ratio of hard martensite and further improving ductility, when adding Cu, the amount is preferably 1.000% or less, and 0.200% or less. It is more preferable.

Sn: 0.200% or less, Sb: 0.200% or less Sn and Sb suppress decarburization in an area of several tens of μm on the steel plate surface layer caused by nitriding and oxidation of the steel plate surface, so they may be added as necessary. Adding it is effective in ensuring strength and material stability. When adding Sn and Sb, it is preferable to add each to 0.002% or more. Further, in order to obtain better toughness, when adding Sn and Sb, the content thereof is preferably 0.200% or less, and more preferably 0.050% or less.

Ta: 0.100% or less Like Ti and Nb, Ta generates alloy carbides and alloy carbonitrides and contributes to high strength. In addition, by partially forming a solid solution in Nb carbide and Nb carbonitride and forming composite precipitates such as (Nb, Ta) (C, N), coarsening of the precipitates is significantly suppressed and precipitation strengthening is achieved. This is thought to have the effect of stabilizing the contribution of For this reason, it is preferable to contain Ta. Here, when Ta is added, it is preferably 0.001% or more. The upper limit of the amount of Ta is not particularly limited, but from the viewpoint of reducing costs, when adding Ta, the content is preferably 0.100% or less, and preferably 0.050% or less. More preferred.

Ca: 0.0050% or less, Mg: 0.0050% or less, Zr: 0.0050% or less, REM: 0.0050% or less Ca, Mg, Zr, and REM make the shape of the sulfide spherical and improve moldability. It is an effective element to improve the negative effects of sulfide on When these elements are added, it is preferable to add each of them in an amount of 0.0005% or more. Furthermore, in order to better prevent the increase of inclusions, etc., and better prevent surface and internal defects, when adding Ca, Mg, Zr, and REM, the amount of each should be 0.0050% or less. is preferable, and more preferably 0.0020% or less.

The present embodiment can also be suitably applied to high-strength steel plates in which hydrogen embrittlement is particularly a problem. By applying vibration to the steel plate coil C made of high-strength steel plate in the dehydrogenation device 300a or by applying the manufacturing method of this steel plate, the amount of diffusible hydrogen in the steel is reduced and the hydrogen resistance is increased. A high-strength steel plate with excellent embrittlement properties can be obtained. For example, the steel plate manufactured in this embodiment may be a high-strength steel plate having a tensile strength of 590 MPa or more, more preferably 1180 MPa or more, and still more preferably 1470 MPa or more. Note that the tensile strength of the steel plate is measured in accordance with JIS Z 2241 (2011). Delayed fracture due to hydrogen embrittlement is often a problem in high-strength steel plates, but according to this embodiment, it is possible to manufacture high-strength steel plates with excellent hydrogen embrittlement resistance without compromising tensile strength. can.

Further, according to the dehydrogenation device and the method for manufacturing a steel plate according to the present embodiment, it is also possible to manufacture a stainless steel with excellent hydrogen embrittlement resistance by adding vibration to a known stainless steel. Hereinafter, the component composition and the reason for its limitation will be explained when the steel plate is a stainless steel plate.

[Essential ingredients]
C: 0.001% or more and 0.400% or less C is an essential element for obtaining high strength in stainless steel. However, when the C content exceeds 0.400%, it combines with Cr and precipitates as carbides during tempering in steel manufacturing, and the carbides deteriorate the corrosion resistance and toughness of the steel. On the other hand, if the C content is less than 0.001%, sufficient strength cannot be obtained, and if it exceeds 0.400%, the deterioration becomes noticeable. Therefore, the C content is set to 0.001% or more and 0.400% or less. The C content is preferably 0.005% or more. Further, the C content is preferably 0.350% or less.

Si: 0.01% or more and 2.00% or less Si is an element useful as a deoxidizing agent. This effect can be obtained by setting the Si content to 0.01% or more. However, when Si is contained excessively, Si dissolved in the steel deteriorates the workability of the steel. Therefore, the upper limit of the Si content is set to 2.00%. The Si content is preferably 0.05% or more. Further, the Si content is preferably 1.8% or less.

Mn: 0.01% or more and 5.00% or less Mn has the effect of increasing the strength of steel. These effects can be obtained by containing 0.01% or more of Mn. However, when the Mn content exceeds 5.00%, the workability of the steel decreases. Therefore, the upper limit of the Mn content is set to 5.00%. The Mn content is preferably 0.05% or more. Further, the Mn content is preferably 4.6% or less.

P: 0.001% or more and 0.100% or less Since P is an element that promotes grain boundary fracture due to grain boundary segregation, a lower content is preferable, and the upper limit is set to 0.100%. Preferably the P content is 0.030% or less. More preferably, the P content is 0.020% or less. Note that the lower limit of the P content is not particularly limited, but from the viewpoint of production technology, it is set to 0.001% or more.

S: 0.0001% or more and 0.0200% or less S is an element that exists in the form of sulfide inclusions such as MnS and reduces ductility and corrosion resistance, especially when the content exceeds 0.0200%. In some cases, these adverse effects are noticeable. Therefore, it is desirable that the S content be as low as possible, and the upper limit of the S content is 0.0200%. Preferably the S content is 0.010% or less. More preferably, the S content is 0.005% or less. Note that the lower limit of the S content is not particularly limited, but from the viewpoint of production technology, it is set to 0.0001% or more.

Cr: 9.0% or more and 28.0% or less Cr is a basic element constituting stainless steel, and is also an important element that exhibits corrosion resistance. When considering corrosion resistance in a harsh environment of 180°C or higher, if the Cr content is less than 9%, sufficient corrosion resistance cannot be obtained, while if it exceeds 28.0%, the effect is saturated and there is a problem in terms of economic efficiency. arise. Therefore, the Cr content is set to 9.0% or more and 28.0% or less. The Cr content is preferably 10.0% or more. Further, the Cr content is preferably 25.0% or less.

Ni: 0.01% or more and 40.0% or less Ni is an element that improves the corrosion resistance of stainless steel, but if it is less than 0.01%, its effect will not be fully demonstrated. In addition to hardening and deteriorating formability, it also makes stress corrosion cracking more likely. Therefore, the Ni content is set to 0.01% or more and 40.0% or less. The Ni content is preferably 0.1% or more. Further, the Ni content is preferably 30.0% or less.

N: 0.0005% or more and 0.500% or less N is an element harmful to improving the corrosion resistance of stainless steel, but is also an austenite-forming element. If the content exceeds 0.5%, it will precipitate as nitrides during heat treatment, and the corrosion resistance and toughness of stainless steel will deteriorate. Therefore, the upper limit of the N content is set to 0.500%, preferably 0.20%.

Al: 3.000% or less,
Al is added as a deoxidizing element and also has the effect of suppressing peeling of oxide scale. However, adding more than 3.000% results in a decrease in elongation and deterioration in surface quality. Therefore, the upper limit of the Al content is set to 3.000%. Although the lower limit of the Al content is not particularly limited, it is preferably 0.001% or more. More preferably, the Al content is 0.01% or more. Further, the Al content is preferably 2.5% or less.

[Optional ingredients]
The composition of the stainless steel is further expressed in mass%: Ti: 0.500% or less, Nb: 0.500% or less, V: 0.500% or less, W: 2.000% or less, B: 0.0050%. Below, Mo: 2.000% or less, Cu: 3.000% or less, Sn: 0.500% or less, Sb: 0.200% or less, Ta: 0.100% or less, Ca: 0.0050% or less, It may further contain at least one element selected from the group consisting of Mg: 0.0050% or less, Zr: 0.0050% or less, and REM: 0.0050% or less.

Ti: 0.500% or less Ti is an element added to combine with C, N, and S to improve corrosion resistance, intergranular corrosion resistance, and deep drawability. However, if it is added in an amount exceeding 0.500%, the solid solution Ti will harden the stainless steel and deteriorate the toughness. Therefore, the upper limit of the Ti content is set to 0.500%. Although the lower limit of the Ti content is not particularly limited, it is preferably 0.003% or more. The Ti content is more preferably 0.005% or more. Further, the Ti content is preferably 0.300% or less.

Nb: 0.500% or less Nb, like Ti, is an element added to combine with C, N, and S to improve corrosion resistance, intergranular corrosion resistance, and deep drawability. Further, in addition to improving workability and high-temperature strength, it is added as necessary to suppress crevice corrosion and promote re-passivation. However, since excessive addition causes the stainless steel to become hard and deteriorates formability, the upper limit of the Nb content is set to 0.500%. Although the lower limit of the Nb content is not particularly limited, it is preferably 0.003% or more. The Nb content is more preferably 0.005% or more. Further, the Nb content is preferably 0.300% or less.

V: 0.500% or less V is added as necessary to suppress crevice corrosion. However, excessive addition makes stainless steel hard and deteriorates formability, so the upper limit of the V content is set to 0.500%. Although the lower limit of the V content is not particularly limited, the V content is preferably 0.01% or more, and more preferably 0.03% or more. Further, the V content is preferably 0.300% or less.

W: 2.000% or less W contributes to improving corrosion resistance and high temperature strength, so it is added as necessary. However, since addition of more than 2.000% makes stainless steel hard, leading to deterioration of toughness and increase in cost during production of steel sheets, the upper limit of the W content is set at 2.000%. Although the lower limit of the W content is not particularly limited, it is preferably 0.050% or more. More preferably, the W content is 0.010% or more. Further, the W content is preferably 1.500% or less.

B: 0.0050% or less An element that improves the secondary workability of products by segregating at grain boundaries. In addition to suppressing vertical cracking during secondary processing of parts, it is added as necessary to prevent cracking in winter. However, excessive addition results in deterioration of workability and corrosion resistance. Therefore, the upper limit of the B content is set to 0.0050%. Although the lower limit of the B content is not particularly limited, it is preferably 0.0002% or more. More preferably, the B content is 0.0005% or more. Further, the B content is preferably 0.0035% or less.

Mo: 2.000% or less Mo is an element that improves corrosion resistance, and is an element that suppresses crevice corrosion, especially when it has a crevice structure. However, if it exceeds 2.0%, moldability will deteriorate significantly, so the upper limit of its content is set at 2.000%. Although the lower limit of the Mo content is not particularly limited, it is preferably 0.005% or more. More preferably, the Mo content is 0.010% or more. Further, the Mo content is preferably 1.500% or less.

Cu: 3.000% or less Cu, like Ni and Mn, is an austenite stabilizing element and is effective in refining crystal grains through phase transformation. Further, it is added as necessary to suppress crevice corrosion and promote repassivation. However, excessive addition causes hardening and deterioration of toughness and formability, so the upper limit of its content is set at 3.000%. Although the lower limit of the Cu content is not particularly limited, it is preferably 0.005% or more. More preferably, the Cu content is 0.010% or more. Further, the Cu content is preferably 2.000% or less.

Sn: 0.500% or less Sn contributes to improving corrosion resistance and high temperature strength, so it is added as necessary. However, if added in excess of 0.500%, slab cracking may occur during steel sheet production, so the upper limit of its content is set to 0.500% or less. Although the lower limit of the Sn content is not particularly limited, it is preferably 0.002% or more. It is more preferable that the Sn content is 0.005% or more. Further, the Sn content is preferably 0.300% or less.

Sb: 0.200% or less Sb is an element that segregates at grain boundaries and acts to increase high-temperature strength. However, if it exceeds 0.200%, Sb segregation will occur and cracks will occur during welding, so the upper limit of the content is set at 0.200%. Although the lower limit of the Sb content is not particularly limited, it is preferably 0.002% or more. More preferably, the Sb content is 0.005% or more. Further, the Sb content is preferably 0.100% or less.

Ta: 0.100% or less Ta is added as necessary because it combines with C and N and contributes to improving toughness. However, if it is added in excess of 0.100%, the effect will be saturated and the manufacturing cost will increase, so the upper limit of the content is set at 0.100%. Although the lower limit of the Ta content is not particularly limited, it is preferably 0.002% or more. More preferably, the Ta content is 0.005% or more. Further, the Ta content is preferably 0.080% or less.

Ca: 0.0050% or less, Mg: 0.0050% or less, Zr: 0.0050% or less, REM (Rare Earth Metal): 0.0050% or less Ca, Mg, Zr and REM have a sulfide shape. It is an effective element for spheroidizing and improving the adverse effects of sulfide on formability. When adding any of these elements, the content of each element is preferably 0.0005% or more. However, when each content is excessive, inclusions and the like increase, and surface and internal defects may occur. Therefore, when adding any of these elements, the content of each element should be 0.0050% or less. Although the lower limit of the content of these elements is not particularly limited, it is preferable that the content of each element is 0.0002% or more. The content of each element is more preferably 0.0005% or more. Further, the content of each element is preferably 0.0035% or less.

[[Annealing equipment]]
[[Annealing process]]
The cold-rolled steel sheet and hot-rolled steel sheet described above may be annealed. That is, the present steel plate manufacturing system may include an annealing device that anneals cold-rolled steel plates and hot-rolled steel plates. The timing of annealing is not particularly limited, but since hydrogen generally enters the steel during the annealing process, annealing is performed before adding vibration in order to ultimately obtain a steel plate with excellent hydrogen embrittlement resistance. It is preferable to apply it to The annealing device may be a batch annealing furnace or a continuous annealing device.

[Batch annealing]
When performing the annealing process using a batch annealing furnace, the steel sheet manufacturing system includes a batch annealing furnace that performs batch annealing on a cold-rolled coil or a hot-rolled coil to obtain an annealed coil, and the annealed coil as the steel sheet coil C. It has a dehydrogenation device 300a. A batch annealing furnace performs batch annealing on a cold-rolled coil or a hot-rolled coil to produce an annealed coil. Note that in this specification, batch annealing means heating and holding in a batch annealing furnace, and does not include slow cooling after heating and holding. The annealed coil after annealing is cooled by furnace cooling in a batch annealing furnace, air cooling, or the like. The dehydrogenation device 300a uses a steel plate coil C as an annealing coil, and applies vibration to the steel plate coil C under the above-described conditions. Although the dehydrogenation device 300a may be provided separately from the batch annealing furnace, the housing section 80 and the heating section of the dehydrogenation device 300a may also serve as the batch annealing furnace. In other words, the dehydrogenation device 300a may be implemented by providing the batch annealing furnace with a vibration applying device 60 that applies vibration to the steel sheet coil C housed in the furnace to produce a product coil. When the housing section 80 and the heating section of the dehydrogenation device 300a also serve as a batch annealing furnace, the vibration can be applied after the annealing coil is cooled to room temperature after the batch annealing. It is also possible to add As mentioned above, diffusible hydrogen can be reduced more efficiently when the temperature of the steel sheet is higher. Therefore, it is also possible to perform batch annealing after cooling the annealed coil to room temperature, thereby reducing vibration while cooling the annealed coil. By adding hydrogen, diffusible hydrogen in steel can be reduced more efficiently.

When performing the annealing process using a batch annealing furnace, the steel plate manufacturing method includes a step of batch annealing a cold rolled coil or hot rolled coil obtained by winding a cold rolled steel plate or hot rolled steel plate to obtain an annealed coil. The annealed coil is used as the steel plate coil, and vibration is applied to the annealed coil under the above-mentioned conditions. First, a cold-rolled steel sheet or a hot-rolled steel sheet is wound up by a known method to form a cold-rolled coil or a hot-rolled coil. Next, the cold rolled coil or the hot rolled coil is placed in a batch annealing furnace, and batch annealing is performed in the batch annealing furnace to obtain an annealed coil. The annealed coil after annealing is cooled by furnace cooling in a batch annealing furnace, air cooling, or the like. Next, vibrations are applied to the annealed coil under the conditions described above. Vibration may be applied to the annealed coil during batch annealing, that is, while the cold-rolled coil or hot-rolled coil is being held under heat. Furthermore, the vibration may be applied after batch annealing, that is, after the cold-rolled coil or hot-rolled coil is heated and held. The vibration may be applied after the annealed coil is cooled to room temperature after batch annealing, or may be applied while the annealed coil is being cooled. As mentioned above, diffusible hydrogen can be reduced more efficiently when the temperature of the steel sheet is higher, so vibrations are applied to the annealed coil during batch annealing or while cooling the annealed coil after batch annealing. is preferred. The application of vibration to the annealed coil can be performed within the batch annealing furnace, or can be performed by taking the annealed coil out of the batch annealing furnace. Preferably, vibration is applied to the annealing coil in a batch annealing furnace. By applying vibration to an annealing coil in a batch annealing furnace, diffusible hydrogen in steel can be efficiently reduced.

[Annealing using continuous annealing equipment]
Annealing can also be performed by passing a cold rolled steel plate or a hot rolled steel plate through a continuous annealing device (Continuous Annealing Line: CAL). When performing the annealing process using a continuous annealing device, the steel sheet manufacturing system includes a pre-annealing device that discharges the cold-rolled steel sheet or the hot-rolled steel sheet from the cold-rolled coil or the hot-rolled coil, and the cold-rolled steel sheet or the hot-rolled steel sheet. a continuous annealing furnace that continuously anneals the annealed steel sheet to produce an annealed steel sheet; an annealed steel sheet winding device that winds up the annealed steel sheet to obtain an annealed coil; and a dehydrogenation device 300a that turns the annealed coil into the steel sheet coil C. has. The pre-annealing payout device pays out a cold rolled steel plate or a hot rolled steel plate from a cold rolled coil or a hot rolled coil, and supplies the cold rolled steel plate or hot rolled steel plate to CAL. Although the configuration of the CAL is not particularly limited, in one example, the CAL has a continuous annealing furnace in which a heating zone, a soaking zone, and a cooling zone are arranged in this order. The cooling zone may be composed of multiple cooling zones, in which case some of the cooling zones may be a holding zone that holds the cold-rolled steel strip in the cooling process within a certain temperature range, or a holding zone that holds the cold-rolled steel strip in the cooling process and reheats the steel plate in the cooling process. It may also be a reheating zone. Further, a preheating zone may be provided on the upstream side of the heating zone in the sheet passing direction. The pre-anneal payout device may be a payoff reel provided upstream of the continuous annealing furnace of the CAL. The annealed steel sheet winding device may be a tension reel provided downstream of the continuous annealing furnace of the CAL. In CAL, (A) a cold-rolled steel sheet or a hot-rolled steel sheet is discharged from a cold-rolled coil or a hot-rolled coil by a payoff reel, and (B) a heating zone, a soaking zone, and a cooling zone are separated from the upstream side in the sheet threading direction. The steel sheet is passed through a continuous annealing furnace located in the furnace, and (B-1) the cold-rolled steel sheet or hot-rolled steel sheet is annealed in the heating zone and the soaking zone to form an annealed steel sheet, and (B-2) it is annealed in the cooling zone. The steel plate is cooled and continuously annealed, (C) the annealed steel plate discharged from the continuous annealing furnace is continuously passed through the plate, and (D) the steel plate is wound up with a tension reel to form an annealed coil. The dehydrogenation device 300a uses the annealed coil as a steel plate coil C and applies vibration to the annealed coil under the above-described conditions. By applying the vibration, the amount of diffusible hydrogen in the steel can be reduced, and an annealed steel sheet with excellent hydrogen embrittlement resistance can be obtained. Note that the cooling method and cooling rate of the steel plate in the cooling zone are not particularly limited, and any cooling such as gas jet cooling, mist cooling, water cooling, etc. may be used.

When performing the annealing process using a continuous annealing device, the method for producing a steel plate includes a step of discharging the cold rolled steel sheet from the cold rolled coil, a step of continuously annealing the cold rolled steel sheet to obtain an annealed steel sheet, and a step of the annealing. and a step of winding up a steel plate to obtain an annealed coil, and the annealed coil is used as the steel plate coil. In CAL, (A) a steel plate coil is unloaded by a payoff reel, and (B) the steel plate is passed from the upstream side in the threading direction into an annealing furnace in which a heating zone, a soaking zone, and a cooling zone are located. , (B-1) Annealing the steel plate in the heating zone and soaking zone, (B-2) Cooling the steel plate in the cooling zone to perform continuous annealing, and (C) Continuously annealing the steel plate discharged from the annealing furnace. The steel plate is passed through the steel plate, and (D) the steel plate is wound up using a tension reel to form an annealed coil. By applying vibration to the annealed coil under the conditions described above, a cold-rolled steel sheet or a hot-rolled steel sheet with excellent hydrogen embrittlement resistance can be obtained.

[[Plated steel sheet]]
Moreover, the dehydrogenation apparatus 300a according to this embodiment can also be applied to the production of plated steel sheets. The steel sheet manufacturing system according to this application example includes a plating device that forms a plating film on the surface of a hot-rolled steel sheet or a cold-rolled steel sheet to produce a plated steel sheet, and a plated steel sheet that winds up the plated steel sheet to obtain a plated steel sheet coil. It has a winding device and a dehydrogenation device 300a that uses the plated steel sheet coil as the steel sheet coil C. The plating apparatus forms a plating film on the surface of a hot-rolled steel sheet or a cold-rolled steel sheet as a base steel sheet to obtain a plated steel sheet. The plated steel sheet winding device winds up the plated steel sheet to form a plated steel sheet coil. The dehydrogenation device 300a uses the plated steel coil as a steel plate coil C and applies vibration to the plated steel coil under the above-described conditions. By applying the vibration, the amount of diffusible hydrogen in the steel can be reduced, and a plated steel sheet with excellent hydrogen embrittlement resistance can be obtained.

Alternatively, a plated steel plate may be obtained by forming a plating film on the surface of a hot-rolled steel plate or a cold-rolled steel plate as a base steel plate, and the plated steel plate may be used as a steel plate coil to which vibration is applied. When applying vibration to a plated steel plate coil, the method of manufacturing the steel plate includes a process of forming a plating film on the surface of a hot-rolled steel plate or a cold-rolled steel plate to obtain a plated steel plate, and a process of winding up the plated steel plate and applying the plating process to the plated steel plate. and a step of obtaining a steel plate coil, and the plated steel plate coil is used as the steel plate coil.

[Formation of plating film using continuous hot-dip galvanizing equipment]
The type of plating device is not particularly limited, but may be, for example, a hot-dip galvanizing device. The hot-dip galvanizing equipment may be a continuous hot-dip galvanizing line (CGL) in one example. Although the configuration of the CGL is not particularly limited, in one example, the CGL includes a continuous annealing furnace in which a heating zone, a soaking zone, and a cooling zone are arranged in this order, and hot-dip galvanizing equipment provided after the cooling zone. In CGL, (A) a cold rolled steel sheet or a hot rolled steel sheet is discharged from a cold rolled coil or a hot rolled coil by a payoff reel, and (B) a heating zone, a soaking zone, and a cooling zone are separated from the upstream side in the sheet threading direction. (B-1) The hot-rolled steel sheet or cold-rolled steel sheet is annealed in a reducing atmosphere containing hydrogen in the soaking zone to produce an annealed steel sheet, and (B-2 ) Cooling the annealed steel sheet in a cooling zone to perform continuous annealing, (C) Continue passing the annealed steel sheet discharged from the annealing furnace, and (C-1) Located downstream of the continuous annealing furnace in the sheet passing direction. An annealed steel sheet is immersed in a hot-dip galvanizing bath, and the annealed steel sheet is subjected to hot-dip galvanizing treatment to form a hot-dip galvanized steel sheet, and (D) the hot-dip galvanized steel sheet is wound up using a tension reel to form a hot-dip galvanized steel sheet coil. . The dehydrogenation device 300a uses the hot-dip galvanized steel sheet coil as the steel sheet coil C and applies vibration to the hot-dip galvanized steel sheet coil under the above-described conditions. By applying the vibration, the amount of diffusible hydrogen in the steel can be reduced, and a hot-dip galvanized steel sheet with excellent hydrogen embrittlement resistance can be obtained.

Although the method of forming a plating film on the surface of a hot-rolled steel sheet or a cold-rolled steel sheet is not particularly limited, the plating process may include a hot-dip galvanizing process. That is, a hot-rolled steel sheet or a cold-rolled steel sheet may be subjected to hot-dip galvanizing treatment to produce a hot-dip galvanized steel sheet. In one example, a continuous hot-dip galvanizing line (CGL) can be used to hot-dip galvanize a steel sheet. In CGL, the steel sheet coil is (A) delivered by a payoff reel, and (B) the hot-rolled steel sheet or cold-rolled steel sheet is placed into an annealing furnace in which a heating zone, a soaking zone, and a cooling zone are located from the upstream side in the sheet threading direction. (B-1) In the soaking zone, the hot-rolled steel sheet or cold-rolled steel sheet is annealed in a reducing atmosphere containing hydrogen to form an annealed steel sheet, and (B-2) in the cooling zone, the annealed steel sheet is cooled. (C) continue to pass the annealed steel plate discharged from the annealing furnace; (D) wind up the annealed steel plate with a tension reel to form an annealed coil; C-1) Includes a step of subjecting the annealed steel sheet to hot-dip galvanizing treatment by immersing the annealed steel sheet in a hot-dip galvanizing bath located downstream of the annealing furnace in the sheet passing direction. The wound annealed coil is a hot-dip galvanized steel sheet coil made of hot-dip galvanized steel sheet. By applying vibration to the hot-dip galvanized steel sheet coil under the above-described conditions, a hot-dip galvanized steel sheet with excellent hydrogen embrittlement resistance can be obtained.

Further, the plating apparatus may include a hot-dip galvanizing apparatus and an alloying furnace following the hot-dip galvanizing apparatus. In one example, after manufacturing a hot-dip galvanized steel sheet using CGL, following the above-mentioned step (C-1), (C-2) the steel sheet is placed in an alloying furnace located downstream of the hot-dip galvanizing bath in the sheet passing direction. The hot-dip galvanizing is heated and alloyed by passing through the plate. The alloyed hot-dip galvanized steel sheet that has been passed through the alloying furnace and alloyed is wound up to become an alloyed hot-dip galvanized steel sheet coil. The dehydrogenation device 300a uses the alloyed hot-dip galvanized steel sheet coil as the steel sheet coil C and applies vibration to the alloyed hot-dip galvanized steel sheet coil under the above-described conditions. By applying the vibration, an alloyed hot-dip galvanized steel sheet with excellent hydrogen embrittlement resistance can be obtained.

Further, the plating process may include a hot-dip galvanizing process and a subsequent alloying process. That is, the hot-dip galvanized steel sheet may be further subjected to alloying treatment to obtain an alloyed hot-dip galvanized steel sheet, and vibration may be applied to the hot-dip galvanized steel sheet. In one example, after manufacturing a hot-dip galvanized steel sheet using CGL, following the above-mentioned step (C-1), (C-2) the steel sheet is placed in an alloying furnace located downstream of the hot-dip galvanizing bath in the sheet passing direction. The hot-dip galvanizing is heated and alloyed by passing through the plate. The alloyed hot-dip galvanized steel sheet that has been passed through the alloying furnace and alloyed is wound up to become an alloyed hot-dip galvanized steel sheet coil. By applying vibration to the alloyed hot-dip galvanized steel sheet coil under the above-mentioned conditions, it is possible to obtain an alloyed hot-dip galvanized steel sheet with excellent hydrogen embrittlement resistance.

Moreover, the plating apparatus can form an Al plating film and a Fe plating film in addition to a zinc plating film. Further, the plating device is not limited to a hot-dip plating device, but may be an electroplating device.

Further, the type of plating film that can be formed on the surface of the steel plate to which vibration is applied is not particularly limited, and may be an Al plating film or an Fe plating film. The method for forming the plating film is not limited to the hot-dip plating process, but may also be an electroplating process.

The steel sheet manufacturing system processes shape correction and surface roughness for hot rolled steel sheets, cold rolled steel sheets, and plated steel sheets having various plating films on the surface of the hot rolled steel sheets or cold rolled steel sheets obtained as described above. It may further include a skin pass rolling device that performs skin pass rolling for the purpose of adjustment and the like. In other words, in the method for manufacturing this steel sheet, the hot rolled steel sheet, the cold rolled steel sheet, and the plated steel sheet having various plating films on the surface of the hot rolled steel sheet or cold rolled steel sheet obtained as described above are subjected to shape correction. Also, skin pass rolling can be performed for the purpose of adjusting surface roughness. The reduction ratio in skin pass rolling is preferably controlled to 0.1% or more, and preferably 2.0% or less. By setting the rolling reduction ratio of skin pass rolling to 0.1% or more, the effect of shape correction and the effect of adjusting surface roughness can be obtained more suitably, and the rolling reduction ratio can also be controlled more suitably. Further, by setting the rolling reduction ratio of skin pass rolling to 2.0% or less, productivity is better. Note that the skin pass rolling device may be a device that is continuous with the CGL or CAL (in-line), or may be a device that is discontinuous with the CGL or CAL (off-line). Skin pass rolling may be performed at the desired rolling reduction at once, or skin pass rolling may be performed in several steps to achieve the desired rolling reduction. In addition, the steel plate manufacturing system includes a resin or oil coating on the surface of the hot-rolled steel plate, cold-rolled steel plate, and plated steel plate having various plating films on the surface of the hot-rolled steel plate or cold-rolled steel plate obtained as described above. It may further include coating equipment for performing various coating treatments. That is, various painting treatments such as resin or oil coating are applied to the surface of the hot-rolled steel sheet, cold-rolled steel sheet, and plated steel sheet having various plating films on the surface of the hot-rolled steel sheet or cold-rolled steel sheet obtained as described above. You can also do that.

<Embodiment 2>
A dehydrogenation device according to Embodiment 2 of the present invention includes a dispensing device for dispensing a steel strip from a steel plate coil, a threading device for passing the steel strip, a winding device for winding the steel strip, and a dispensing device for dispensing a steel strip from a steel plate coil, a threading device for passing the steel strip through the steel strip, a winding device for winding the steel strip, and a winding device for winding the steel strip. A vibration adding device that applies vibration to the steel strip while it is being passed through the plate device so that the frequency of vibration of the steel strip is 100 to 100,000 Hz and the maximum amplitude of the steel strip is 10 nm to 500 μm. and has.

Further, the method for manufacturing a steel sheet according to Embodiment 2 of the present invention includes a step of discharging a steel strip from a steel sheet coil, a threading step of passing the steel strip through the steel strip, and winding the steel strip to form a product coil. The threading step includes vibrating the steel strip so that the frequency of vibration of the steel strip is 100 to 100,000 Hz and the maximum amplitude of the steel strip is 10 nm to 500 μm. Includes a vibration addition process that adds .

A steel sheet that has been optionally annealed after hot rolling or cold rolling, or a plated steel sheet that has been further formed with a plating film, is wound into a coil to form a steel sheet coil. Since the mass of the steel sheet coil is often different from the packed mass at the time of shipment, division into packed masses is performed at the recoil line. The steel strip is paid out from the steel plate coil by the payout device, and the paid out steel strip is rewound again by the unwinding device, and when it reaches a predetermined packing mass, it is sheared and divided. In this embodiment, vibrations are applied to the steel strip discharged by the recoil line. According to this embodiment, since vibration is applied to the steel strip during threading, it is possible to apply vibration evenly over the entire length of the steel strip. Note that the dehydrogenation device according to this embodiment is a discontinuous device (offline) from the continuous annealing device or the continuous hot-dip galvanizing device, and the dehydrogenation device is capable of annealing, plating, and hot-dip galvanizing the steel strip. Does not include equipment for processing.

(Vibration adding device 60)
A vibration adding device can be used to add vibration. In one example, the vibration adding device is configured to vibrate the steel strip being threaded by an external force (attractive force) applied by the electromagnet 63 to the steel strip being threaded, similar to the vibration adding device 60 according to the first embodiment described above. can be done. The configuration of the vibration applying device 60 can be the same as in Embodiment 1, except that the object to which vibration is applied is not the steel plate coil but the steel strip being threaded.

It is sufficient that the electromagnet 63 is provided so as to face one surface of the steel strip being threaded, but it may be provided so as to face both the front and back surfaces. However, in that case, it is preferable to shift the height position so that the electromagnet 63 on one side is not at the same height position as the electromagnet 63 on the other side.

(Vibration adding device 70)
In another example, the vibration adding device vibrates the steel strip being threaded due to an external force (gravitational force) applied by the vibrator to the steel strip being threaded, similar to the vibration adding device 70 according to the first embodiment described above. It can be configured as follows. As shown in FIG. 4A, the vibration applying device 70 has a vibrator 72 that contacts the steel strip being threaded, and can be configured so that the steel strip S is vibrated by the vibrator 72. The configuration of the vibration applying device 70 can be the same as in Embodiment 1, except that the object to which vibration is applied is not the steel plate coil but the steel strip being threaded.

[[Dehydrogenation equipment]]
FIG. 7 shows a view of a dehydrogenation device 300b used in the method of manufacturing a steel plate according to the present embodiment, with the width direction of the steel strip S facing toward you. FIG. 7 is a diagram illustrating an example of a dehydrogenation device for reducing diffusible hydrogen in steel by applying vibration by a vibration applying device 60 to the steel strip S during threading. As shown in FIG. 7, in this dehydrogenation apparatus 300b, a vibration applying device 60 is disposed in the process of threading the steel strip S discharged by the dispensing device. Although not shown, in each vibration adding device 60, an amplifier 62, a power source 65, and a controller 61 are coupled to each electromagnet 63, and a vibration detector 64 is further coupled to the controller 61. The electromagnet 63 applies vibration to the steel strip S. As shown in FIG. 7, the vibration adding device 60 may be provided only on one side of the front and back sides of the steel strip S during threading, or the vibration applying device 60 may be provided on both the front and back sides of the steel strip S during threading. It may be provided so as to vibrate. By providing the vibration applying device 60 on both the front and back surfaces of the steel strip S during threading, it is possible to control the vibration application timing and more efficiently reduce the amount of diffusible hydrogen in the steel. Although not shown, the dehydrogenation device 300b includes a threading device for threading the steel strip S from the payout device to the winding device. The threading device includes, for example, a threading roll that threads the steel strip S toward a winding device.

It is preferable that a plurality of electromagnets 63 be installed along the width direction of the steel strip at a predetermined interval from the surface of the steel strip S being threaded. By applying vibration from each electromagnet 63 toward the surface of the steel strip S being threaded, it is possible to apply vibration uniformly in the width direction of the surface. By arranging a plurality of electromagnets 63 located along the width direction of the steel strip along the threading direction, a sufficient amount of time can be secured for the surface of the steel strip S to be subjected to vibration.

The form for holding the electromagnets 63 at regular intervals in the dehydrogenation device 300b is not particularly limited, but for example, a box-shaped part is provided in the strip passing route so as to cover the steel strip S being threaded, and the box-shaped part Electromagnets 63 can be fixed at regular intervals on the inner wall of.

FIG. 8 shows an example of a dehydrogenation device for reducing diffusible hydrogen in steel by applying vibration by a vibration adding device 70 to the steel strip S during threading. In FIG. 8, the width direction of the steel strip S is shown in the front. As shown in FIG. 8, the dehydrogenation device 300b arranges the vibrator 72 of the vibration applying device 70 during the threading process of the steel strip S dispensed by the dispensing device. Although not shown, in each vibration adding device 70, a controller 71 and a vibration detector 73 are coupled to each vibrator 72, and vibration is applied to the steel strip S from the vibrator 72. It has become so. As shown in FIG. 8, the vibrator 72 is arranged so as to be in contact with the steel strip S being threaded. The vibration adding device 70 may be provided only on one side of the front and back sides of the steel strip S during threading, or may be provided so that the steel strip S vibrates on both the front and back sides of the steel strip S during threading. Good too. By providing the vibration applying device 70 on both the front and back surfaces of the steel strip S during threading, it is possible to control the vibration application timing and more efficiently reduce the amount of diffusible hydrogen in the steel.

It is preferable that a plurality of vibrators 72 be installed along the width direction of the steel strip so that the vibrators 72 come into contact with the surface of the steel strip S being threaded. By applying vibration from each vibrator 72 to the surface of the steel strip S being threaded, the vibration can be applied uniformly to the surface in the width direction. By arranging a plurality of vibrators 72 along the steel strip width direction along the sheet passing direction, it is possible to sufficiently secure the time during which the surface of the steel strip S is subjected to vibration.

The form for holding the vibrators 72 at regular intervals in the dehydrogenation device 300b is not particularly limited, but for example, a box-shaped part is provided in the threading path so as to cover the steel strip S being threaded, and the box-shaped part is The vibrators 72 can be fixed to the inner wall of the section at regular intervals.

In this embodiment, the frequency of vibration and the maximum amplitude of vibration applied to the steel strip during threading can be the same as in the first embodiment.

[[Vibration addition time]]
In the recoil line, unlike continuous annealing equipment or continuous hot-dip galvanizing equipment, there is no need to adjust the sheet passing speed in consideration of the annealing time. Therefore, according to this embodiment, vibration can be applied to the steel strip without restrictions on irradiation time. Since it is presumed that the longer the vibration is applied, the more diffusible hydrogen can be reduced, the vibration is preferably applied for one minute or more. The duration of vibration is more preferably 30 minutes or longer, and even more preferably 60 minutes or longer. On the other hand, from the viewpoint of productivity, the vibration application time is preferably 30,000 minutes or less, more preferably 10,000 minutes or less, and even more preferably 1,000 minutes or less. The vibration application time is determined by the threading speed of the steel strip S and the position of the vibration application device (for example, the number along the threading direction of a device group consisting of a plurality of vibration application devices 60 located along the width direction of the steel sheet). It can be adjusted by

According to this embodiment, the amount of diffusible hydrogen in the product coil obtained after vibration application can be reduced to 0.5 mass ppm or less. Hydrogen embrittlement can be prevented by reducing the amount of diffusible hydrogen in the product coil to 0.5 mass ppm or less. The amount of diffusible hydrogen in the steel after vibration is applied is preferably 0.3 mass ppm or less, more preferably 0.2 mass ppm or less. The amount of diffusible hydrogen in the steel after vibration is applied can be measured in the same manner as in the first embodiment.

[[Heating device]]
[[Holding temperature of steel strip]]
Further, as shown in FIGS. 7 and 8, the dehydrogenation device 300b may further include a heating device 74 for applying vibration while heating the steel strip S at 300° C. or lower. The temperature of the steel strip S in the vibration adding step is not particularly limited. This is because, according to the present embodiment, diffusible hydrogen in the steel can be reduced without heating and holding the steel strip S. However, by applying vibration while heating the steel strip S by the heating section, the diffusion rate of hydrogen can be further increased, and therefore the amount of diffusible hydrogen in the steel can be further reduced. Therefore, the temperature of the steel strip S when applying vibration is preferably 30°C or higher, more preferably 50°C or higher, and even more preferably 100°C or higher. The upper limit of the temperature of the steel strip S in the vibration application step is not particularly limited, but from the viewpoint of suitably preventing changes in the structure of the steel strip S, it is preferably 300° C. or less. In this embodiment, the temperature of the steel strip S when applying vibration is based on the temperature of the surface of the steel strip S. The surface temperature of the steel strip can be measured with a general radiation thermometer. Although the form in which the heating device 74 is provided is not particularly limited, the heating device 74 can be provided in the threading path of the steel strip S, as shown in FIGS. 7 and 8, for example. By providing the heating device 74 on the passing path of the steel strip S, the steel strip S can be heated uniformly. When the heating device 74 is provided in the threading path of the steel strip S, it is preferable to provide the heating device 74 upstream of the vibration applying device 60 in the threading path, as shown in FIGS. 7 and 8. By providing the heating device 74 upstream of the vibration applying device 60 in the sheet passing path, vibration can be applied to the sufficiently heated steel strip S. Further, for example, by covering the steel sheet being threaded with the box-shaped part described above and installing a heater on the side wall of the box-shaped part, it is possible to apply vibration to the steel strip S while keeping it heated. Further, by blowing high-temperature air generated externally into the box-shaped part and circulating it within the box-shaped part, it is possible to add vibration to the steel strip S while keeping it heated. The heating method is not particularly limited, and may be either a combustion method or an electric method. In one example, heating device 74 may be an induction heating device.

The dehydrogenation device 300b according to the present embodiment may further include a vibration damping portion that prevents the vibration from being transmitted to the outside of the dehydrogenation device 300b. Although the specific configuration of the vibration damping section is not particularly limited, the vibration damping section may be a damping material that encloses and covers the steel strip S and the electromagnet 63, for example.

Below, an application example of this embodiment will be described in more detail.

[[Hot rolled steel plate]]
Similar to Embodiment 1, the dehydrogenation device 300b and the method for manufacturing a steel sheet according to this embodiment can be applied to manufacturing a hot rolled steel sheet.

The steel plate manufacturing system according to this application example includes a hot rolling device that hot-rolls a steel slab to produce a hot-rolled steel plate, and a hot-rolled steel plate winding device that winds up the hot-rolled steel plate to obtain a hot-rolled coil. and a dehydrogenation device 300b in which the hot rolled coil is the steel plate coil. A hot-rolled steel sheet is taken out from a hot-rolled coil manufactured by a known hot-rolling machine and passed through the hot-rolled steel sheet, and vibrations are applied to the hot-rolled steel sheet under the above-mentioned conditions during the threading process, thereby reducing the diffusion in the steel. By reducing the amount of hydrogen embrittlement, it is possible to obtain a hot rolled steel sheet with excellent hydrogen embrittlement resistance.

Similar to Embodiment 1, the method for manufacturing a steel sheet according to this embodiment can be applied to manufacturing a hot rolled steel sheet. The method for manufacturing a steel plate according to this application example includes the steps of hot rolling a steel slab to obtain a hot rolled steel plate, and winding up the hot rolled steel plate to obtain a hot rolled coil. The coil is the steel plate coil described above. The method of manufacturing the hot-rolled coil before applying vibration is not particularly limited, and may be, for example, the manufacturing method illustrated in Embodiment 1. The hot-rolled steel sheet is taken out from the hot-rolled coil and passed through the hot-rolled steel sheet, and vibration is applied to the hot-rolled steel sheet under the above-mentioned conditions to reduce the amount of diffusible hydrogen in the steel and improve its durability. A hot rolled steel sheet with excellent hydrogen embrittlement properties can be obtained.

[[Cold rolled steel sheet]]
The dehydrogenation device 300b and the method for manufacturing a steel plate according to the present embodiment can also be applied to manufacturing a cold rolled steel plate.

The steel plate manufacturing system according to this application example includes a cold rolling device that cold-rolls a hot-rolled steel plate to produce a cold-rolled steel plate, and a cold-rolled steel plate winder that winds up the cold-rolled steel plate to obtain a cold-rolled coil. and a dehydrogenation device 300b in which the cold-rolled coil is the steel sheet coil C. A cold-rolled steel plate is obtained by subjecting a known hot-rolled steel plate to cold rolling using a known cold-rolling device. A cold-rolled steel sheet winding device winds up the cold-rolled steel sheet into a cold-rolled coil. The cold-rolled coil is used as a steel sheet coil C, and a cold-rolled steel sheet is taken out from the cold-rolled coil and passed through the cold-rolled steel sheet. By reducing the amount of diffusible hydrogen, a cold-rolled steel sheet with excellent hydrogen embrittlement resistance can be obtained.

The method for manufacturing a steel plate according to this application example includes a step of cold rolling a hot rolled steel sheet to obtain a cold rolled steel sheet, and a step of winding the cold rolled steel sheet to obtain a cold rolled coil. The coil is the steel plate coil described above. The method of manufacturing the cold-rolled coil before applying vibration is not particularly limited, and can be, for example, the manufacturing method illustrated in Embodiment 1. The cold-rolled steel sheet is taken out from the cold-rolled coil and passed through the cold-rolled steel sheet, and vibration is applied to the cold-rolled steel sheet under the above-mentioned conditions to reduce the amount of diffusible hydrogen in the steel and improve its durability. A cold-rolled steel sheet with excellent hydrogen embrittlement properties can be obtained.

Although the composition of the hot-rolled steel sheet and cold-rolled steel sheet to which vibration is applied by the dehydrogenation device 300b is not limited, according to this embodiment, the tensile strength is 590 MPa or more, more preferably 1180 MPa or more, and still more preferably 1470 MPa or more. By applying vibration in the dehydrogenation device 300b to the high-strength steel plate, the amount of diffusible hydrogen in the steel can be reduced, and a high-strength steel plate with excellent hydrogen embrittlement resistance can be obtained.

The compositions of the hot-rolled steel sheet and the cold-rolled steel sheet can be, for example, the compositions exemplified in Embodiment 1.

[[Annealing equipment]]
Similar to Embodiment 1, the steel plate manufacturing system may include an annealing device that anneals cold-rolled steel plates and hot-rolled steel plates. The timing of annealing is not particularly limited, but since hydrogen generally enters the steel during the annealing process, annealing is performed before adding vibration in order to ultimately obtain a steel plate with excellent hydrogen embrittlement resistance. It is preferable to apply it to The annealing device may be a batch annealing furnace or a continuous annealing device.

[[Annealing process]]
As in Embodiment 1, the cold-rolled steel sheet and the hot-rolled steel sheet may be annealed. Although the timing of annealing is not particularly limited, it is preferable to perform annealing before the vibration application step. The annealing process can be performed using a batch annealing furnace or a continuous annealing device.

[Batch annealing]
When performing the annealing process using a batch annealing furnace, the steel sheet manufacturing system includes a batch annealing furnace that performs batch annealing on a cold-rolled coil or a hot-rolled coil to obtain an annealed coil, and the annealed coil as the steel sheet coil C. It has a dehydrogenation device 300b. The annealed coil after annealing is cooled by furnace cooling in a batch annealing furnace, air cooling, or the like. The payout device pays out the annealed steel sheet from the annealing coil and supplies it to the threading device, and the threading device threads the annealed steel sheet. The vibration applying device 60 applies vibration to the annealed steel sheet during threading under the above-mentioned conditions. By applying the vibration, the amount of diffusible hydrogen in the steel can be reduced, and an annealed steel sheet with excellent hydrogen embrittlement resistance can be obtained.

When performing the annealing process using a batch annealing furnace, the steel plate manufacturing method involves a process of winding a cold-rolled steel plate or hot-rolled steel plate into a cold-rolled coil or hot-rolled coil, and a process of winding the cold-rolled steel plate or hot-rolled steel plate into a cold-rolled coil or hot-rolled coil, and and a step of performing annealing to obtain an annealed coil, and the annealed coil is used as the steel plate coil. The annealed coil after annealing is cooled by furnace cooling in a batch annealing furnace, air cooling, or the like. Next, the annealed steel plate is taken out from the annealing coil and passed through the annealed steel plate, and vibration is applied to the annealed steel plate under the above-mentioned conditions during passing, thereby reducing the amount of diffusible hydrogen in the steel and making it hydrogen resistant. A hot-rolled steel sheet or a cold-rolled steel sheet with excellent embrittlement properties can be obtained.

[Annealing using continuous annealing equipment]
Annealing can also be performed by passing a cold rolled steel plate or a hot rolled steel plate through a continuous annealing device (Continuous Annealing Line: CAL). When performing the annealing process using a continuous annealing device, the steel sheet manufacturing system includes a pre-annealing device that discharges the cold-rolled steel sheet or the hot-rolled steel sheet from the cold-rolled coil or the hot-rolled coil, and the cold-rolled steel sheet or the hot-rolled steel sheet. a continuous annealing furnace that continuously anneals the annealed steel sheet to produce an annealed steel sheet, an annealed steel sheet winding device that winds up the annealed steel sheet to obtain an annealed coil, and a dehydrogenation device 300b that turns the annealed coil into the steel sheet coil C; has. The configuration of the continuous annealing device is the same as in the first embodiment. The discharging device of the dehydrogenation device 300b discharges the annealed steel sheet from the annealing coil and supplies it to the threading device, and the threading device threads the annealed steel sheet. The vibration applying device 60 applies vibration to the annealed steel sheet during threading under the above-mentioned conditions. By applying the vibration, the amount of diffusible hydrogen in the steel can be reduced, and an annealed steel sheet with excellent hydrogen embrittlement resistance can be obtained.

When performing the annealing process using a continuous annealing device, the annealed coil before vibration is applied can be manufactured in the same manner as in the first embodiment. To obtain a cold-rolled steel sheet or a hot-rolled steel sheet with excellent hydrogen embrittlement resistance by paying out the annealed steel strip from the annealing coil and applying vibration under the above-mentioned conditions to the annealed steel sheet during threading. Can be done.

[[Plated steel sheet]]
Similar to Embodiment 1, the dehydrogenation device 300b and the method for manufacturing a steel sheet according to this embodiment can also be applied to manufacturing a plated steel sheet.

The steel sheet manufacturing system according to this application example includes a plating device that forms a plating film on the surface of a hot-rolled steel sheet or a cold-rolled steel sheet to produce a plated steel sheet, and a plated steel sheet that winds up the plated steel sheet to obtain a plated steel sheet coil. It has a winding device and a dehydrogenation device 300b that uses the plated steel sheet coil as the steel sheet coil C. The type of plating film that can be formed on the surface of a hot-rolled steel sheet or a cold-rolled steel sheet is not particularly limited, and may be an Al plating film or an Fe plating film in addition to a zinc plating film. The method for forming the plating film is not limited to the hot-dip plating process, but may also be an electroplating process.

Further, the method for manufacturing a steel sheet according to this application example includes a step of forming a plating film on the surface of a hot-rolled steel sheet or a cold-rolled steel sheet to obtain a plated steel sheet, and a step of winding up the plated steel sheet to obtain a plated steel sheet coil. and the plated steel sheet coil is the steel sheet coil.

[Formation of plating film using continuous hot-dip galvanizing equipment]
The type of plating device is not particularly limited, but may be, for example, a hot-dip galvanizing device. The hot-dip galvanizing equipment may be a continuous hot-dip galvanizing line (CGL) in one example. The configuration of CGL may be the same as in the first embodiment. The dispensing device of the dehydrogenation device 300b dispenses the hot-dip galvanized steel sheet from the hot-dip galvanized steel sheet coil manufactured by CGL and supplies it to the sheet threading device, and the sheet passing device threads the hot-dip galvanized steel sheet. The vibration applying device 60 applies vibration to the annealed steel sheet during threading under the above-mentioned conditions. By applying the vibration, the amount of diffusible hydrogen in the steel can be reduced, and a hot-dip galvanized steel sheet with excellent hydrogen embrittlement resistance can be obtained.

A hot-dip galvanized steel sheet may be obtained by subjecting the steel sheet to a hot-dip galvanizing process before applying vibration. In one example, a continuous hot-dip galvanizing line (CGL) can be used to hot-dip galvanize the steel strip. The configuration of the CGL can be the same as in the first embodiment. The hot-dip galvanized steel coil before applying vibration can be manufactured in the same manner as in the first embodiment. The hot-dip galvanized steel sheet coil is produced by taking out the hot-dip galvanized steel sheet and threading it through the hot-dip galvanized steel sheet, and applying vibration under the above-mentioned conditions to the hot-dip galvanized steel sheet during the threading process. Galvanized steel sheets can be obtained.

Further, the plating apparatus may include a hot-dip galvanizing apparatus and an alloying furnace following the hot-dip galvanizing apparatus. That is, in the method for manufacturing the present steel sheet, the plating treatment may include a hot-dip galvanizing step and a subsequent alloying step. As the plating apparatus having the alloying furnace, the CGL having the alloying furnace downstream of the hot-dip galvanizing bath in the sheet passing direction, as exemplified in Embodiment 1, can be used. The alloyed hot-dip galvanized steel sheet is taken out from the alloyed hot-dip galvanized steel sheet coil formed by the hot-dip galvanizing process and the subsequent alloying process, and the alloyed hot-dip galvanized steel sheet is subjected to vibration under the conditions described above. By adding , an alloyed hot-dip galvanized steel sheet with excellent hydrogen embrittlement resistance can be obtained.

Similar to Embodiment 1, the steel sheet manufacturing system is configured to produce a hot rolled steel sheet, a cold rolled steel sheet, and a plated steel sheet having various plating films on the surface of the hot rolled steel sheet or cold rolled steel sheet obtained as described above. It may further include a skin pass rolling device that performs skin pass rolling for the purpose of correction, adjustment of surface roughness, and the like. In addition, the steel plate manufacturing system includes a resin or oil coating on the surface of the hot-rolled steel plate, cold-rolled steel plate, and plated steel plate having various plating films on the surface of the hot-rolled steel plate or cold-rolled steel plate obtained as described above. It may further include coating equipment for performing various coating treatments.

That is, in the method for manufacturing the present steel sheet, Embodiment 1 is applied to the hot-rolled steel sheet, cold-rolled steel sheet, and plated steel sheet having various plating films on the surface of the hot-rolled steel sheet or cold-rolled steel sheet obtained as described above. Similarly, skin pass rolling can be performed. In addition, various painting treatments such as resin or oil coating are applied to the hot-rolled steel sheet, cold-rolled steel sheet, and plated steel sheet having various plating films on the surface of the hot-rolled steel sheet or cold-rolled steel sheet obtained as described above. You can also do that.

<Example 1>
A steel material having the composition shown in Table 1, with the remainder consisting of Fe and unavoidable impurities, was melted in a converter and made into a steel slab by continuous casting. The obtained steel slab was hot rolled, then cold rolled, and further annealed to obtain a cold rolled steel plate (CR). Some of the cold-rolled steel sheets were further subjected to hot-dip galvanizing treatment to obtain hot-dip galvanized steel sheets (GI). Some of the hot-dip galvanized steel sheets were further subjected to alloying treatment to obtain alloyed hot-dip galvanized steel sheets (GA). Each of CR, GI, and GA had a plate thickness of 1.4 mm and a width of 1000 mm. As the CAL, a CAL in which a heating zone, a soaking zone, and a cooling zone were arranged in this order was used. The CGL used included a continuous annealing furnace in which a heating zone, a soaking zone, and a cooling zone were arranged in this order, and a hot-dip galvanizing facility provided after the cooling zone. A general batch annealing furnace was used as the batch annealing furnace.

Vibration was applied to the obtained steel plate coils of CR, GI, and GA, or to the steel strip discharged from the steel plate coils. Vibration was applied using the vibration applying device shown in FIG. 1 or 4 under the conditions of frequency, maximum amplitude, and irradiation time shown in Table 2. In Table 2, A indicates the case in which vibrations were applied to the steel plate coil, and B indicates the case in which vibrations were applied to the discharged steel strip. When applying vibration to the steel plate coil, a dehydrogenation device shown in FIGS. 5(a), (c), and 6 was used. When applying vibration to the steel strip, a dehydrogenation device shown in FIGS. 3 and 4(a) was used. When applying vibration to a steel plate coil (outer diameter: 1500 mm, inner diameter: 610 mm, width: 1000 mm), the size of the housing part was 2500 mm in the height direction, 2000 mm in depth, and 2500 mm in the width direction. When applying vibrations using electromagnets, the electromagnets were placed on the inner wall of the housing so as to surround the steel plate coil. When applying vibration using a vibrator, vibrators 72 were arranged on the surface of the steel plate coil at intervals of 10° in the center angle along the circumferential direction of the steel plate coil. When vibration was applied to the steel strip during threading, electromagnets or vibrators were placed on both the front and back sides of the steel strip during threading. Six electromagnets were arranged evenly along the width direction of the steel strip from the ends of the steel strip in the width direction. Note that room temperature in Table 2 means around 25°C. The maximum amplitude can be determined by fixing the position of the vibration applying device (that is, the distance between the vibration applying device and the steel strip S or steel plate coil C) and adjusting the frequency and current value of the current flowing through the electromagnet. Alternatively, adjustment was made by adjusting the frequency and current value of the DC pulse current flowing through the vibrator. In addition, the irradiation time was adjusted by adjusting the driving time of the vibration applying device when vibration was applied to the steel plate coil. When applying vibration to the discharged steel strip, the duration of vibration application was adjusted by adjusting the threading speed of the steel strip.

After applying vibration, each steel plate was evaluated for tensile properties, amount of diffusible hydrogen in the steel, stretch flangeability, and bendability using the methods described below, and the results are shown in Table 2.

The tensile test was conducted in accordance with JIS Z 2241 (2011). JIS No. 5 test pieces were taken from each steel plate after vibration was applied so that the tensile direction was perpendicular to the rolling direction of the steel plate. Using each test piece, a tensile test was conducted at a crosshead displacement rate of 1.67×10 ⁻¹ mm/s, and the TS (tensile strength) was measured.

Stretch flangeability was evaluated by a hole expansion test. The hole expansion test was conducted in accordance with JIS Z 2256. A sample of 100 mm x 100 mm was taken by shearing from the obtained steel plate. A hole with a diameter of 10 mm was punched into the sample with a clearance of 12.5%. Using a die with an inner diameter of 75 mm, a conical punch with an apex angle of 60° was pressed into the hole while the periphery of the hole was held down with a wrinkle pressing force of 9 tons (88.26 kN), and the hole diameter at the crack generation limit was measured. The critical hole expansion rate: λ (%) was determined from the following equation (4), and the hole expansion property was evaluated from the value of this critical hole expansion rate.
Critical hole expansion rate: λ (%) = {(D _f − D ₀ )/D ₀ }×100 (4)
However, in the above formula, D _f is the hole diameter (mm) at the time of crack occurrence, and D ₀ is the initial hole diameter (mm). Regardless of the strength of the steel plate, it was determined that the stretch flangeability was good when the value of λ was 20% or more.

The bending test was conducted in accordance with JIS Z 2248. A strip-shaped test piece with a width of 30 mm and a length of 100 mm was taken from the obtained steel plate so that the direction parallel to the rolling direction of the steel plate was the axial direction of the bending test. Thereafter, a bending test was conducted using the V-block method with a bending angle of 90° and a pushing load of 100 kN and a pushing holding time of 5 seconds. In addition, in the present invention, a 90° V bending test was performed, and the ridgeline at the bending apex was observed with a 40x magnification microscope (RH-2000: manufactured by Hirox Co., Ltd.), and cracks with a crack length of 200 μm or more were observed. The bending radius at which the bending radius became impossible was defined as the minimum bending radius (R). The bending test was judged to be good when the value (R/t) obtained by dividing R by the plate thickness (t) was 5.0 or less.

The amount of diffusible hydrogen in steel was measured according to the method described above.

As shown in Table 2, in the example of the present invention, since the vibration addition process was performed, the amount of hydrogen was small, and the steel plate had excellent stretch flangeability (λ) and bendability (R/t), which are indicators of hydrogen embrittlement resistance. was able to manufacture. On the other hand, in the comparative example, one or more of stretch flangeability (λ) and bendability (R/t) is poor.

In the example of the present invention, since vibration was applied to the steel plate, it was possible to manufacture a steel plate with excellent hydrogen embrittlement resistance.

60 vibration adding device 61 controller 62 amplifier 63 electromagnet 63A magnet 63A1 magnetic pole face 63B coil 64 vibration detector 65 power supply 70 vibration adding device 71 controller 72 vibrator 73 vibration detector 74 heating device 80 housing section 90 coil holding section 300a, 300b Dehydrogenator S Steel strip C Steel plate coil

Claims (34)

a storage section that stores a steel plate coil obtained by winding a steel strip into a coil shape;
A vibration adding device that applies vibration to the steel plate coil housed in the housing part so that the frequency of vibration of the steel plate coil is 100 to 100,000 Hz, and the maximum amplitude of the steel plate coil is 10 nm to 500 μm. and,
A dehydrogenation device with The vibration adding device includes an electromagnet having a magnetic pole face facing away from the surface of the steel plate coil, and is configured such that the steel plate coil vibrates due to an external force applied by the electromagnet to the steel plate coil. 1. The dehydrogenation device according to 1. The dehydrogenation device according to claim 1, wherein the vibration applying device includes a vibrator that contacts the steel plate coil, and is configured so that the steel plate coil vibrates with the vibrator. The dehydrogenation device according to any one of claims 1 to 3, further comprising a heating section for applying the vibration while heating the steel plate coil. a payout device that pays out a steel strip from a steel plate coil;
A threading device for threading the steel strip;
a winding device that winds up the steel strip;
The steel strip is held at 300° C. or less while the steel strip is being passed through the sheet threading device, the vibration frequency of the steel strip is 100 to 100,000 Hz, and the steel strip is rotated in the thickness direction of the steel strip. a vibration adding device that applies vibration for 20 seconds or more so that the maximum amplitude of is 10 nm to 500 μm;
A dehydrogenation device with The vibration applying device includes an electromagnet having a magnetic pole face facing away from the surface of the steel strip during threading, and is configured to cause the steel strip to vibrate due to an external force applied to the steel strip by the electromagnet. The dehydrogenation apparatus according to claim 5. The dehydrogenation device according to claim 5, wherein the vibration applying device includes a vibrator that contacts the steel strip during threading, and is configured so that the steel strip is vibrated by the vibrator. The dehydrogenation device according to any one of claims 5 to 7, further comprising a heating section for applying the vibration while heating the steel strip. The dehydrogenation device according to claim 1 or 5, further comprising a vibration damping part that prevents the vibration from being transmitted to the outside of the dehydrogenation device. a hot rolling device that hot-rolls a steel slab to produce a hot-rolled steel plate;
a hot-rolled steel sheet winding device that winds up the hot-rolled steel sheet to obtain a hot-rolled coil;
The dehydrogenation device according to claim 1 or 5, wherein the hot rolled coil is the steel plate coil,
A steel sheet manufacturing system with A cold rolling device that cold-rolls a hot-rolled steel plate to produce a cold-rolled steel plate;
a cold-rolled steel sheet winding device that winds up the cold-rolled steel sheet to obtain a cold-rolled coil;
The dehydrogenation device according to claim 1 or 5, wherein the cold rolled coil is the steel plate coil,
A steel sheet manufacturing system with A batch annealing furnace that performs batch annealing on a cold rolled coil or a hot rolled coil to obtain an annealed coil;
The dehydrogenation device according to claim 1 or 5, wherein the annealed coil is the steel plate coil,
A steel sheet manufacturing system with a pre-annealing payout device for paying out a cold rolled steel plate or a hot rolled steel plate from a cold rolled coil or a hot rolled coil, respectively;
a continuous annealing furnace that continuously anneals the cold-rolled steel plate or hot-rolled steel plate to produce an annealed steel plate;
an annealed steel plate winding device that winds up the annealed steel plate to obtain an annealed coil;
The dehydrogenation device according to claim 1 or 5, wherein the annealed coil is the steel plate coil,
A steel sheet manufacturing system with A plating device that forms a plating film on the surface of a hot-rolled steel sheet or a cold-rolled steel sheet to obtain a plated steel sheet;
a plated steel plate winding device that winds up the plated steel plate to obtain a plated steel plate coil;
The dehydrogenation device according to claim 1 or 5, wherein the plated steel sheet coil is the steel sheet coil.
A steel sheet manufacturing system with The steel sheet manufacturing system according to claim 14, wherein the plating device is a hot-dip galvanizing device. The steel sheet manufacturing system according to claim 14, wherein the plating device includes a hot-dip galvanizing device and a subsequent alloying furnace. The steel plate manufacturing system according to claim 14, wherein the plating device is an electroplating device. A product is produced by adding vibration to a steel plate coil obtained by winding a steel strip into a coil shape such that the frequency of vibration of the steel plate coil is 100 to 100,000 Hz, and the maximum amplitude of the steel plate coil is 10 nm to 500 μm. A method for producing a steel plate, including a process of adding vibration to form a coil. The method for manufacturing a steel plate according to claim 18, wherein the vibration applying step is performed while maintaining the steel plate coil at 300°C or lower. A process of discharging the steel strip from the steel plate coil,
A threading step of threading the steel strip;
a step of winding the steel strip into a product coil;
The threading process is performed with respect to the steel strip so that the frequency of vibration of the steel strip is 100 to 100,000 Hz, and the maximum amplitude of the steel strip in the thickness direction is 10 nm to 500 μm. Including a vibration adding step of adding vibration for 20 seconds or more ,
The vibration application step is performed while maintaining the steel strip at 300°C or less,
Method of manufacturing steel plates. A process of hot rolling a steel slab to make a hot rolled steel plate;
a step of winding the hot-rolled steel sheet to obtain a hot-rolled coil;
The method for manufacturing a steel plate according to any one of claims 18 to 20 , wherein the hot rolled coil is the steel plate coil. A process of cold-rolling a hot-rolled steel plate to obtain a cold-rolled steel plate;
a step of winding the cold-rolled steel sheet to obtain a cold-rolled coil;
The method for manufacturing a steel plate according to any one of claims 18 to 20 , wherein the cold rolled coil is the steel plate coil. The method for manufacturing a steel plate according to any one of claims 18 to 20 , comprising a step of batch annealing a cold rolled coil or a hot rolled coil to obtain an annealed coil, and using the annealed coil as the steel plate coil. A step of discharging a cold-rolled steel plate or a hot-rolled steel plate from a cold-rolled coil or a hot-rolled coil, respectively;
Continuously annealing the cold rolled steel plate or the hot rolled steel plate to obtain an annealed steel plate;
Winding the annealed steel plate to obtain an annealed coil;
The method for manufacturing a steel plate according to any one of claims 18 to 20 , wherein the annealing coil is the steel plate coil. A plating process in which a plating film is formed on the surface of a hot-rolled steel sheet or a cold-rolled steel sheet to obtain a plated steel sheet;
a step of winding up the plated steel sheet to obtain a plated steel sheet coil;
The method for manufacturing a steel plate according to any one of claims 18 to 20 , wherein the plated steel plate coil is the steel plate coil. The method for manufacturing a steel sheet according to claim 25 , wherein the plating step includes a hot-dip galvanizing step. The method for manufacturing a steel sheet according to claim 25 , wherein the plating step includes a hot-dip galvanizing step and a subsequent alloying step. The method for manufacturing a steel plate according to claim 25 , wherein the plating step includes an electroplating step. The method for manufacturing a steel plate according to any one of claims 18 to 20 , wherein the product coil is made of a high-strength steel plate having a tensile strength of 590 MPa or more. The product coil has a mass percentage of
C: 0.030% or more and 0.800% or less,
Si: 0.01% or more and 3.00% or less,
Mn: 0.01% or more and 10.00% or less,
P: 0.001% or more and 0.100% or less,
S: 0.0001% or more and 0.0200% or less,
Any one of claims 18 to 20 , comprising a base steel plate having a composition containing N: 0.0005% or more and 0.0100% or less and Al: 2.000% or less, with the balance consisting of Fe and inevitable impurities. A method for manufacturing a steel plate according to item 1. The component composition further includes, in mass%,
Ti: 0.200% or less,
Nb: 0.200% or less,
V: 0.500% or less,
W: 0.500% or less,
B: 0.0050% or less,
Ni: 1.000% or less,
Cr: 1.000% or less,
Mo: 1.000% or less,
Cu: 1.000% or less,
Sn: 0.200% or less,
Sb: 0.200% or less,
Ta: 0.100% or less,
Ca: 0.0050% or less,
Mg: 0.0050% or less,
The method for producing a steel plate according to claim 30 , further comprising at least one element selected from the group consisting of Zr: 0.0050% or less and REM: 0.0050% or less. The product coil has a mass percentage of
C: 0.001% or more and 0.400% or less,
Si: 0.01% or more and 2.00% or less,
Mn: 0.01% or more and 5.00% or less,
P: 0.001% or more and 0.100% or less,
S: 0.0001% or more and 0.0200% or less,
Cr: 9.0% or more and 28.0% or less,
Ni: 0.01% or more and 40.0% or less,
Any one of claims 18 to 20 , comprising a stainless steel plate having a composition containing N: 0.0005% or more and 0.500% or less and Al: 3.000% or less, with the balance consisting of Fe and inevitable impurities. A method for manufacturing a steel plate according to item 1. The component composition further includes, in mass%,
Ti: 0.500% or less,
Nb: 0.500% or less,
V: 0.500% or less,
W: 2.000% or less,
B: 0.0050% or less,
Mo: 2.000% or less,
Cu: 3.000% or less,
Sn: 0.500% or less,
Sb: 0.200% or less,
Ta: 0.100% or less,
Ca: 0.0050% or less,
Mg: 0.0050% or less,
The method for producing a steel plate according to claim 32 , further comprising at least one element selected from the group consisting of Zr: 0.0050% or less and REM: 0.0050% or less. The method for manufacturing a steel plate according to any one of claims 18 to 20 , wherein the product coil has a diffusible hydrogen amount of 0.50 mass ppm or less.

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