Continuous annealing apparatus and continuous hot-dip galvanizing apparatus, and method for manufacturing steel sheet

Abstract

This invention provides a continuous annealing apparatus capable of manufacturing steel sheets with excellent resistance to hydrogen embrittlement. The continuous annealing apparatus (100) of this invention comprises: a coil unwinding machine (10) for unwinding cold-rolled steel sheets (S) from a cold-rolled coil (C); an annealing furnace (20) for continuously annealing the cold-rolled steel sheet (S) by passing it through the furnace, the annealing furnace (20) having a heating zone (22), a soaking zone (24), and a cooling zone (26) arranged upstream of the furnace in the direction of the passage, wherein the cold-rolled steel sheet (S) is annealed in the heating zone (22) and the soaking zone (24) in a reducing atmosphere containing hydrogen, and the cold-rolled steel sheet (S) is cooled in the cooling zone (26); and the unwinding machine (10) for continuously annealing the cold-rolled steel sheet (S) from a cold-rolled coil (C); and the unwinding machine (10) for continuously annealing the cold-rolled steel sheet (S) by passing it through the furnace. Downstream equipment (30) for the cold-rolled steel sheet (S) discharged from the annealing furnace (20) to continue passing through the plate; tension coiler (50) for winding the cold-rolled steel sheet (S) in the plate passing through the downstream equipment (30); and vibration auxiliary device (60 or 70) for adding vibration to the cold-rolled steel sheet (S) passing through the plate from the cooling zone (26) to the tension coiler (50) in such a way that the vibration frequency of the cold-rolled steel sheet is 100Hz to 100000Hz and the maximum amplitude of the cold-rolled steel sheet is 10nm to 500μm.

Description

Technical Field

[0001] This invention relates to a continuous annealing apparatus and a continuous hot-dip galvanizing apparatus, as well as a method for manufacturing steel sheets. This invention is particularly applicable to the automotive, home appliance, and building materials industries, and relates to a continuous annealing apparatus and a continuous hot-dip galvanizing apparatus for manufacturing steel sheets with inherently low hydrogen content and excellent resistance to hydrogen embrittlement, as well as a method for manufacturing steel sheets. Background Technology

[0002] For example, when annealed steel sheets and hot-dip galvanized steel sheets are manufactured in continuous annealing and continuous hot-dip galvanizing units, respectively, the annealing is carried out in a reducing atmosphere containing hydrogen. Therefore, hydrogen penetrates into the steel sheet during this annealing process. The hydrogen inherent in the steel sheet reduces its formability, such as ductility, bendability, and tensile flangeability. Furthermore, the hydrogen inherent in the steel sheet causes embrittlement, which can lead to delayed failure. Therefore, treatment to reduce the hydrogen content in the steel sheet is necessary.

[0003] For example, product coils manufactured using continuous annealing and continuous hot-dip galvanizing units can have their hydrogen content reduced by leaving them at room temperature. However, hydrogen takes time to move from the interior to the surface of the steel sheet and then detach from the surface, so several weeks or more are required to fully reduce the hydrogen content. Therefore, the space and time required for such dehydrogenation treatment become a problem in the manufacturing process.

[0004] In addition, Patent Document 1 discloses a method for reducing the hydrogen content in steel by holding annealed steel sheets, hot-dip galvanized steel sheets, or alloyed hot-dip galvanized steel sheets in a temperature range of 50°C to 300°C for 1800 seconds to 43200 seconds.

[0005] Existing technical documents

[0006] Patent documents

[0007] Patent Document 1: International Publication No. 2019 / 188642 Summary of the Invention

[0008] However, Patent Document 1 expresses concern that changes in the microstructure caused by heating could lead to changes in mechanical properties such as increased yield strength and temper embrittlement.

[0009] Therefore, in view of the above-mentioned problems, the present invention aims to provide a continuous annealing apparatus and a continuous hot-dip galvanizing apparatus, as well as a method for manufacturing steel plates with excellent resistance to hydrogen embrittlement, which can manufacture steel plates without compromising production efficiency or changing mechanical properties.

[0010] To solve the aforementioned problems, the inventors conducted repeated and in-depth research and discovered the following phenomenon: In a continuous annealing line (CAL) or continuous hot-dip galvanizing line (CGL), after annealing a steel sheet in a reducing atmosphere containing hydrogen, further vibration at a specified frequency and maximum amplitude is applied to the steel sheet during the cooling process from the annealing temperature to room temperature. This effectively reduces the hydrogen content in the steel sheet. Specifically, it was found that by subjecting the steel sheet to high-frequency micro-vibration with a small maximum amplitude, the hydrogen content in the steel sheet can be reduced effectively. This is presumably due to the following mechanism: Forced micro-vibration of the steel sheet applies repeated bending deformation. As a result, the lattice spacing on the surface increases compared to the thickness of the steel sheet's center. Hydrogen in the steel sheet diffuses towards the surface of the steel sheet, where the lattice spacing is wider and the potential energy is lower, and then escapes from that surface.

[0011] That is, the present invention was completed based on the above circumstances, and its main points are as follows.

[0012] [1] A continuous annealing apparatus, comprising:

[0013] The unwinding machine releases cold-rolled steel sheets from cold-rolled coils;

[0014] An annealing furnace is used to continuously anneal the aforementioned cold-rolled steel sheet by passing it through the plate. The annealing furnace is provided with a heating zone, a soaking zone, and a cooling zone on the upstream side from the plate passage direction. The aforementioned cold-rolled steel sheet is annealed in the aforementioned heating zone and the aforementioned soaking zone in a reducing atmosphere containing hydrogen, and the aforementioned cold-rolled steel sheet is cooled in the aforementioned cooling zone.

[0015] Downstream equipment allows the cold-rolled steel sheet discharged from the annealing furnace to continue passing through the furnace;

[0016] A tension coiler winds the aforementioned cold-rolled steel sheet in the through-plate of the downstream equipment.

[0017] The vibration attachment device applies vibration to the cold-rolled steel sheet passing through the cooling belt and the tension coiler, such that the frequency of the cold-rolled steel sheet is 100Hz to 100000Hz and the maximum amplitude of the cold-rolled steel sheet is 10nm to 500μm.

[0018] [2] According to the continuous annealing apparatus described in [1] above, the vibration additional device is provided on the cooling zone.

[0019] [3] According to the continuous annealing apparatus described in [1] or [2] above, the vibration additional device is provided at a position that can add vibration to the cold-rolled steel sheet in the downstream equipment through plate.

[0020] [4] The continuous annealing apparatus according to any one of [1] to [3] above, wherein the configuration of the vibration addition device and the through speed of the cold-rolled steel sheet are set such that the additional time for adding vibration to the cold-rolled steel sheet is 1 second or more.

[0021] [5] The continuous annealing apparatus according to any one of [1] to [4] above, wherein the vibration additional device includes an electromagnet having a magnetic pole face that is separately opposed to the surface of the cold-rolled steel sheet, and is configured to cause the cold-rolled steel sheet to vibrate by an external force applied to the cold-rolled steel sheet by the electromagnet.

[0022] [6] The continuous annealing apparatus according to any one of [1] to [4] above, wherein the vibration additional device has a vibrator in contact with the cold-rolled steel sheet and is configured to vibrate the cold-rolled steel sheet by means of the vibrator.

[0023] [7] A continuous hot-dip galvanizing apparatus, comprising:

[0024] The continuous annealing apparatus described above [1]; and

[0025] The hot-dip galvanizing bath, which is located downstream of the annealing furnace in the direction of the through plate, is used to immerse the cold-rolled steel sheet and perform hot-dip galvanizing on the cold-rolled steel sheet.

[0026] [8] According to the continuous hot-dip galvanizing apparatus described above [7], the vibration additional device is provided at a position that can add vibration to the cold-rolled steel sheet in the circulating plate of the hot-dip galvanizing bath.

[0027] [9] According to the continuous hot-dip galvanizing apparatus described in [7] or [8] above, the vibration additional device is provided at a position that can add vibration to the cold-rolled steel sheet in the downstream plate of the hot-dip galvanizing bath.

[0028]

[10] According to the continuous hot-dip galvanizing apparatus described above [7], as the downstream equipment, there is an alloying furnace located downstream of the hot-dip galvanizing bath in the direction of the through plate, through which the cold-rolled steel sheet is passed and the hot-dip galvanizing is heated and alloyed.

[0029]

[11] According to the continuous hot-dip galvanizing apparatus described in

[10] above, the vibration additional device is provided at a position that can add vibration to the cold-rolled steel sheet in the swirling plate of the hot-dip galvanizing bath.

[0030]

[12] According to the continuous hot-dip galvanizing apparatus described in

[10] or

[11] above, the vibration additional device is provided at a position that can add vibration to the cold-rolled steel sheet in the downstream plate of the hot-dip galvanizing bath.

[0031]

[13] The continuous hot-dip galvanizing apparatus according to any one of [7] to

[12] above, wherein the configuration of the vibration addition device and the through speed of the cold-rolled steel sheet are set such that the additional time for adding vibration to the cold-rolled steel sheet is 1 second or more.

[0032]

[14] The continuous hot-dip galvanizing apparatus according to any one of [7] to

[13] above, wherein the vibration auxiliary device includes an electromagnet having a magnetic pole face that is separately opposed to the surface of the cold-rolled steel sheet, and is configured to cause the cold-rolled steel sheet to vibrate by an external force applied to the cold-rolled steel sheet by the electromagnet.

[0033]

[15] The continuous hot-dip galvanizing apparatus according to any one of [7] to

[13] above, wherein the vibration auxiliary device has a vibrator in contact with the cold-rolled steel sheet and is configured to vibrate the cold-rolled steel sheet by means of the vibrator.

[0034]

[16] A method for manufacturing a steel plate, comprising the following steps in sequence:

[0035] (A) The process of releasing cold-rolled steel sheets from cold-rolled coils using an unwinding machine;

[0036] (B) In an annealing furnace provided with a heating zone, a soaking zone and a cooling zone on the upstream side of the through plate, the above-mentioned cold-rolled steel sheet is passed through and subjected to the following continuous annealing process, wherein the continuous annealing is (B-1) annealing the above-mentioned cold-rolled steel sheet in the heating zone and the soaking zone in a reducing atmosphere containing hydrogen, and (B-2) cooling the above-mentioned cold-rolled steel sheet in the cooling zone.

[0037] (C) The process of continuing to pass the cold-rolled steel sheet discharged from the annealing furnace; and

[0038] (D) The process of using a tension coiler to wind the above-mentioned cold-rolled steel sheet to produce product coils.

[0039] After process (B-2) and before process (D), a vibration additional process is included: the cold-rolled steel sheet in the through plate is subjected to additional vibration in such a way that the frequency of the cold-rolled steel sheet is 100Hz to 100000Hz and the maximum amplitude of the cold-rolled steel sheet is 10nm to 500μm.

[0040]

[17] In the steel plate manufacturing method described above

[16] , the above-mentioned vibration additional process is carried out in process (B-2).

[0041]

[18] In the steel plate manufacturing method described in

[16] or

[17] above, the above-mentioned vibration additional process is carried out in process (C).

[0042]

[19] According to the steel plate manufacturing method described in

[16] above, the step (C) includes (C-1) immersing the cold-rolled steel plate in a hot-dip galvanizing bath located downstream of the annealing furnace in the plate direction, and performing hot-dip galvanizing on the cold-rolled steel plate.

[0043]

[20] In the steel plate manufacturing method described above

[19] , the vibration additional process is performed before process (C-1).

[0044]

[21] In the steel plate manufacturing method described in

[19] or

[20] above, the above-mentioned vibration additional process is performed after process (C-1).

[0045]

[22] According to the steel plate manufacturing method described above

[19] , the above-mentioned step (C) includes step (C-2) after the above-mentioned step (C-1): passing the above-mentioned cold-rolled steel plate through an alloying furnace located downstream of the hot-dip galvanizing bath in the plate-passing direction, and heating and alloying the above-mentioned hot-dip galvanizing.

[0046]

[23] In the steel plate manufacturing method described above

[22] , the above-mentioned vibration additional process is performed before process (C-1).

[0047]

[24] In the steel plate manufacturing method described in

[22] or

[23] above, the above-mentioned vibration additional process is performed after process (C-1).

[0048]

[25] The method for manufacturing a steel plate according to any one of

[16] to

[24] above, wherein, in the above vibration addition process, the additional time for adding vibration to the above cold-rolled steel plate is set to 1 second or more.

[0049]

[26] The method for manufacturing a steel plate according to any one of

[16] to

[25] above, wherein, in the above-mentioned vibration additional step, the cold-rolled steel plate is vibrated by an external force applied to the cold-rolled steel plate by an electromagnet having a magnetic pole face that is opposed to the surface of the cold-rolled steel plate separately.

[0050]

[27] The method for manufacturing a steel plate according to any one of

[16] to

[25] above, wherein, in the above-mentioned vibration additional process, the cold-rolled steel plate is vibrated by an oscillator that is in contact with the cold-rolled steel plate.

[0051]

[28] The method for manufacturing steel plate according to any one of

[16] to

[27] above, wherein the cold-rolled steel plate is a high-strength steel plate having a tensile strength of 590 MPa or more.

[0052]

[29] The method for manufacturing a steel plate according to any one of

[16] to

[28] above, wherein the cold-rolled steel plate has the following composition: containing, by mass %, C: 0.030 to 0.800%, Si: 0.01 to 3.00%, Mn: 0.01 to 10.00%, P: 0.001 to 0.100%, S: 0.0001 to 0.0200%, N: 0.0005 to 0.0100% and Al: 0.001 to 2.000%, with the remainder consisting of Fe and unavoidable impurities.

[0053]

[30] According to the steel plate manufacturing method described above

[29] , the above-mentioned composition further contains, by mass %, at least one element selected from 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: 0.1000% or less, and REM: 0.0050% or less.

[0054]

[31] The method for manufacturing a steel plate according to any one of

[16] to

[27] above, wherein the cold-rolled steel plate is a stainless steel plate having the following composition, wherein the composition, in mass %, contains C: 0.001 to 0.400%, Si: 0.01 to 2.00%, Mn: 0.01 to 5.00%, P: 0.001 to 0.100%, S: 0.0001 to 0.0200%, Cr: 9.0 to 28.0%, Ni: 0.01 to 40.0%, N: 0.0005 to 0.500%, and Al: 0.001 to 3.000%, with the remainder consisting of Fe and unavoidable impurities.

[0055]

[32] According to the steel plate manufacturing method described in

[31] above, the above-mentioned composition further contains, by mass %, at least one element selected from 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, Zr: 0.1000% or less, and REM: 0.0050% or less.

[0056]

[33] The method for manufacturing steel plate according to any one of

[16] to

[32] above, wherein the product coil has a diffusible hydrogen content of less than 0.50 ppm by mass.

[0057] According to the continuous annealing apparatus and continuous hot-dip galvanizing apparatus of the present invention, as well as the method for manufacturing steel plates, steel plates with excellent resistance to hydrogen embrittlement can be manufactured without compromising production efficiency or altering mechanical properties. Attached Figure Description

[0058] Figure 1 This is a schematic diagram of a continuous annealing apparatus 100 according to one embodiment of the present invention.

[0059] Figure 2 This is a schematic diagram of a continuous hot-dip galvanizing apparatus 200 according to one embodiment of the present invention.

[0060] Figure 3 This is a schematic diagram of a continuous hot-dip galvanizing apparatus 300 according to another embodiment of the present invention.

[0061] Figure 4 This is a schematic diagram illustrating the configuration of the vibration attachment device 60 used in various embodiments of the present invention.

[0062] Figure 5 Figures (A) and (B) are schematic diagrams illustrating examples of the arrangement of the electromagnet 63 of the vibration attachment 60 relative to the cold-rolled steel sheet S in the through plate in various embodiments of the present invention.

[0063] Figure 6 Figures (A) and (B) are schematic diagrams illustrating the manner in which a magnetic field is generated from an electromagnet 63 in various embodiments of the present invention.

[0064] Figure 7A This is a schematic diagram illustrating the configuration of the vibration attachment 70 used in various embodiments of the present invention.

[0065] Figure 7B This is a diagram schematically illustrating an example of how the vibrator 72 of the vibration attachment 70 is arranged relative to the cold-rolled steel sheet S in the through plate.

[0066] Figure 8 (A) and (B) are schematic diagrams showing examples of the positional relationship between the cooling nozzle 26A and the vibration attachment 60 or 70 when the vibration attachment 60 or 70 is installed in the cooling zone 26. Detailed Implementation

[0067] One embodiment of the present invention relates to a continuous annealing line (CAL), and another embodiment of the present invention relates to a continuous hot-dip galvanizing line (CGL).

[0068] The steel plate manufacturing method of one embodiment of the present invention is carried out by a continuous annealing line (CAL) or a continuous hot-dip galvanizing line (CGL).

[0069] Reference Figure 1 The continuous annealing apparatus (CAL) 100 of the first embodiment of the present invention includes an unwinding machine 10 for releasing cold-rolled steel sheet S from cold-rolled coil C; an annealing furnace 20 for continuously annealing the cold-rolled steel sheet S by passing it through the plate; a downstream device 30 for continuing to pass the cold-rolled steel sheet S discharged from the annealing furnace 20 through the plate; and a tension coiler 50 for forming product coil P from the cold-rolled steel sheet S wound in the plate passing through the downstream device 30. In the annealing furnace 20, a heating zone 22, a soaking zone 24, and a cooling zone 26 are provided upstream of the plate passing direction. The cold-rolled steel sheet S is annealed in the heating zone 22 and the soaking zone 24 in a reducing atmosphere containing hydrogen, and the cold-rolled steel sheet S is cooled in the cooling zone 26. It should be noted that it is preferable that the annealing furnace 20 of the CAL 100 has an over-aging treatment zone 28 downstream of the cooling zone 26, but it is not necessary. The cold-rolled steel sheet S is over-aged in the over-aging treatment zone 28. In this embodiment, CAL100 is used to manufacture cold-rolled annealed steel sheet (CR) product coils.

[0070] Reference Figure 1The steel sheet manufacturing method of the first embodiment implemented by the continuous annealing apparatus (CAL) 100 includes the following steps in sequence: (A) a step of releasing the cold-rolled steel sheet (strip) S from the cold-rolled coil C using the unwinding machine 10; (B) a step of continuously annealing the cold-rolled steel sheet S by passing it through an annealing furnace 20, which is provided with a heating zone 22, a soaking zone 24 and a cooling zone 26 on the upstream side of the through-plate direction, wherein the continuous annealing is (B-1) annealing the cold-rolled steel sheet S in a reducing atmosphere containing hydrogen in the heating zone 22 and the soaking zone 24, and (B-2) cooling the cold-rolled steel sheet S in the cooling zone 26; (C) a step of continuing to pass the cold-rolled steel sheet S discharged from the annealing furnace 20 through a through-plate; and (D) a step of winding the cold-rolled steel sheet S using a tension coiler 50 to form a product coil P. It should be noted that in the continuous annealing process (B) using the CAL100 annealing furnace 20, it is preferable (B-3) to perform over-aging treatment on the cold-rolled steel sheet S in an over-aging treatment zone 28 arbitrarily located downstream of the cooling zone 26, but this process is not necessary. This embodiment is a method for manufacturing product coils of cold-rolled annealed steel sheet (CR) using CAL100.

[0071] Reference Figure 2 The second embodiment of the continuous hot-dip galvanizing apparatus (CGL) 200 of the present invention includes an unwinding machine 10 for releasing cold-rolled steel sheet S from cold-rolled coil C; an annealing furnace 20 for continuously annealing the cold-rolled steel sheet S by passing it through the plate; a downstream device 30 for continuing to pass the cold-rolled steel sheet S discharged from the annealing furnace 20 through the plate; and a tension coiler 50 for forming a product coil P by winding the cold-rolled steel sheet S in the plate passing through the downstream device 30. In the annealing furnace 20, a heating zone 22, a soaking zone 24, and a cooling zone 26 are provided upstream of the plate passing direction. The cold-rolled steel sheet S is annealed in the heating zone 22 and the soaking zone 24 in a reducing atmosphere containing hydrogen, and the cold-rolled steel sheet S is cooled in the cooling zone 26. Furthermore, the downstream device 30 in the CGL200 further includes a hot-dip galvanizing bath 31 located downstream of the annealing furnace 20 in the plate-passing direction, for impregnating the cold-rolled steel sheet S and subjecting the cold-rolled steel sheet S to hot-dip galvanizing; and an alloying furnace 33 located downstream of the hot-dip galvanizing bath 31 in the plate-passing direction, for passing the cold-rolled steel sheet S through the plate and heating and alloying it for hot-dip galvanizing. In this embodiment, the CGL200 is used to manufacture product coils of alloyed hot-dip galvanized steel sheet (GA) with an alloyed galvanized layer. It should be noted that, by simply passing the steel sheet S through the alloying furnace 33 without heating and alloying, product coils of hot-dip galvanized steel sheet (GI) with an unalloyed galvanized layer are manufactured.

[0072] Reference Figure 2The steel sheet manufacturing method of the second embodiment, implemented using a continuous hot-dip galvanizing apparatus (CGL) 200, sequentially includes: (A) a step of releasing a cold-rolled steel sheet (strip) S from a cold-rolled coil C using a coil unwinding machine 10; (B) a step of continuously annealing the cold-rolled steel sheet S by passing it through an annealing furnace 20, which is provided with a heating zone 22, a soaking zone 24, and a cooling zone 26 on the upstream side of the through-plate direction, wherein the continuous annealing is (B-1) annealing the cold-rolled steel sheet S in a reducing atmosphere containing hydrogen in the heating zone 22 and the soaking zone 24, and (B-2) cooling the cold-rolled steel sheet S in the cooling zone 26; (C) a step of continuing to pass the cold-rolled steel sheet S discharged from the annealing furnace 20 through a through-plate; and (D) a step of winding the cold-rolled steel sheet S using a tension coiler 50 to form a product coil P. Furthermore, process (C) includes (C-1) immersing the cold-rolled steel sheet S in a hot-dip galvanizing bath 31 located downstream of the annealing furnace 20 in the plate-passing direction, thereby performing hot-dip galvanizing on the cold-rolled steel sheet S; followed by (C-2) passing the cold-rolled steel sheet S through an alloying furnace 33 located downstream of the hot-dip galvanizing bath 31 in the plate-passing direction, thereby performing a heating alloying process for the hot-dip galvanized steel sheet. This embodiment is a method for manufacturing alloyed hot-dip galvanized steel sheet (GA) product coils with an alloyed galvanized layer using CGL200.

[0073] Reference Figure 3 The continuous hot-dip galvanizing apparatus (CGL) 300 of the third embodiment of the present invention does not have an alloying furnace 33, but otherwise has the same structure as CGL 200. In this embodiment, CGL 300 is used to manufacture product coils of hot-dip galvanized steel sheet (GI) with an unalloyed galvanized layer.

[0074] That is, the steel sheet manufacturing method of the third embodiment, which involves performing process (C-1) and not performing process (C-2), can be implemented, for example, using a CGL300 without an alloying furnace 33. Alternatively, it can be implemented by simply passing the steel sheet S through the alloying furnace 33 of a CGL200 without heating for alloying. This embodiment is a method for manufacturing product coils of hot-dip galvanized steel sheet (GI) with an unalloyed galvanized layer using a CGL200 or CGL300.

[0075] The components of CAL in the first embodiment and CGL in the second and third embodiments described above will be explained in detail. Furthermore, each step in the manufacturing method of the steel plate according to the first, second, and third embodiments will be explained in detail.

[0076] [Unwinding machine and equipment from the unwinding machine to the annealing furnace]

[0077] [Process (A)]

[0078] Reference Figures 1-3The unwinding machine 10 releases the cold-rolled steel sheet S from the cold-rolled coil C. That is, in process (A), the unwinding machine 10 releases the cold-rolled steel sheet S from the cold-rolled coil C. The released cold-rolled steel sheet S is supplied to the annealing furnace 20 via the welding machine 11, the cleaning equipment 12, and the inlet looper 13. The upstream equipment between the unwinding machine 10 and the annealing furnace 20 is not limited to these welding machine 11, cleaning equipment 12, and inlet looper 13, and can be any known or arbitrary device.

[0079] Annealing furnace

[0080] [Process (B)]

[0081] Reference Figures 1-3 The annealing furnace 20 continuously anneals the cold-rolled steel sheet S by passing it through the furnace. In the annealing furnace 20, a heating zone 22, a soaking zone 24, and a cooling zone 26 are provided upstream of the furnace in the direction of the furnace passage. The cold-rolled steel sheet S is annealed in a reducing atmosphere containing hydrogen in the heating zone 22 and the soaking zone 24, and cooled in the cooling zone 26. That is, in process (B), the cold-rolled steel sheet S is continuously annealed by passing it through the furnace in the annealing furnace 20, which has a heating zone 22, a soaking zone 24, and a cooling zone 26 upstream of the furnace in the direction of the furnace passage. The cooling zone 26 may consist of multiple cooling zones. Additionally, a preheating zone may be provided upstream of the heating zone 22 in the direction of the furnace passage. It should be noted that... Figure 1 The annealing furnace 20 of the CAL100 shown preferably has an over-aging treatment zone 28 downstream of the cooling zone 26, but this is not necessary. Figures 1-3 In the illustration, each strip is shown as a vertical furnace, but it is not limited to this and can be a horizontal furnace. In the case of a vertical furnace, adjacent strips are connected by throats (throttling sections) that connect the upper or lower parts of each strip.

[0082] (Heating belt)

[0083] The cold-rolled steel sheet S can be directly heated in the heating zone 22 using a burner, or indirectly heated using a radiant tube (RT) or an electric heater. Alternatively, heating can be achieved through induction heating, roll heating, resistance heating, direct current heating, salt bath heating, electron beam heating, etc. The average internal temperature of the heating zone 22 is preferably 500–800°C. Gas from the heat exchange zone 24 flows into the heating zone 22, and a reducing gas is also supplied. As the reducing gas, a mixture of H2 and N2 is typically used; for example, a gas with H2: 1–35% by volume, the remainder consisting of one or both of N2 and Ar, and unavoidable impurities (dew point: approximately -60°C) can be used.

[0084] (All tropical)

[0085] The cold-rolled steel sheet S can be indirectly heated in the heat exchanger 24 using a radiant heating tube (RT). The average internal temperature of the heat exchanger 24 is preferably 600–950°C. A reducing gas is supplied to the heat exchanger 24. As the reducing gas, a mixture of H2 and N2 is typically used, for example, a gas having an H2 content of 1–35% by volume, with the remainder consisting of one or both of N2 and Ar, as well as unavoidable impurities (dew point: approximately -60°C).

[0086] (Cooling zone)

[0087] In cooling zone 26, the cold-rolled steel sheet S is cooled using gas, a mixture of gas and water, or any one of the following: gas or water. As the cold-rolled steel sheet S exits the annealing furnace 20, it is cooled to approximately 100–400°C in CAL and to approximately 470–530°C in CGL. For example... Figure 8 As shown in (A) and (B), a plurality of cooling nozzles 26A are provided along the steel plate conveying path in the cooling zone 26. The cooling nozzles 26A are, for example, circular tubes longer than the width of the steel plate, as described in Japanese Patent Application Publication No. 2010-185101, with the extension direction of the circular tube parallel to the width direction of the steel plate. At the portion of the circular tube opposite the steel plate, a plurality of through holes are provided along the extension direction of the circular tube at predetermined intervals, through which water inside the circular tube is sprayed toward the steel plate. The cooling nozzles are arranged in pairs, facing each other on the surface and back of the steel plate, and multiple pairs (e.g., 5 to 10 pairs) of cooling nozzles are arranged along the steel plate conveying path at predetermined intervals, forming a cooling zone. Preferably, about 3 to 6 cooling zones are arranged along the steel plate conveying path.

[0088] (Expired processing zone)

[0089] Reference Figure 1 In CAL100, the cold-rolled steel sheet S leaving the cooling zone 26 in the over-aging treatment zone 28 is fed to at least one of the following treatments: isothermal holding, reheating, furnace cooling and decooling. The cold-rolled steel sheet S is cooled to about 100 to 400°C in the stage of leaving the annealing furnace 20.

[0090] Downstream equipment

[0091] [Process (C)]

[0092] Reference Figures 1-3 In process (C), the cold-rolled steel sheet S discharged from the annealing furnace 20 continues to pass through the downstream equipment 30. (Refer to...) Figure 1 The CGL100, as downstream equipment 30, has an export looper 35 and a leveling mill 36. (Refer to...) Figure 2 The CGL200, as downstream equipment 30, includes a hot-dip galvanizing bath 31, a gas wiping device 32, an alloying furnace 33, a cooling device 34, an outlet looper 35, and a leveling mill 36. (Refer to...) Figure 3 The CGL300, as downstream equipment 30, includes a hot-dip galvanizing bath 31, a gas wiping device 32, a cooling device 34, an exit looper 35, and a leveling mill 36. However, downstream equipment 30 is not limited to these and can be any known or arbitrary device. For example, downstream equipment 30 can include tension straighteners, chemical forming equipment, surface conditioning equipment, oiling equipment, and inspection equipment.

[0093] (Hot-dip galvanizing bath)

[0094] (Process (C-1))

[0095] Reference Figure 2 , 3 The hot-dip galvanizing bath 31 is located downstream of the annealing furnace 20 in the direction of the through plate, where the cold-rolled steel sheet S is immersed, and the cold-rolled steel sheet S is hot-dip galvanized. That is, in process (C-1), the cold-rolled steel sheet S is immersed in the hot-dip galvanizing bath 31 located downstream of the annealing furnace 20 in the direction of the through plate, and the cold-rolled steel sheet S is hot-dip galvanized. This is related to the downstreammost strip of the annealing furnace (…). Figure 2 , 3 The nozzle 29, connected to the cooling zone 26, is a rectangular component with a cross-section perpendicular to the direction of the cold-rolled steel sheet S, which divides the space for the cold-rolled steel sheet S to pass through. Its front end is immersed in the hot-dip galvanizing bath 31. Therefore, the annealing furnace 20 is connected to the hot-dip galvanizing bath 31. Hot-dip galvanizing can be carried out according to conventional methods.

[0096] Gas can be sprayed onto the cold-rolled steel sheet S from a pair of gas wiping devices 32 that are clamped between the cold-rolled steel sheet S pulled out of the hot-dip galvanizing bath 31, thereby adjusting the amount of molten zinc adhering to both sides of the cold-rolled steel sheet S.

[0097] (Alloying furnace)

[0098] (Process (C-2))

[0099] Reference Figure 2 The alloying furnace 33 is located downstream of the hot-dip galvanizing bath 31 and the gas wiping device 32 in the plate-passing direction, allowing the cold-rolled steel sheet S to pass through the plate and undergo heating and alloying for hot-dip galvanizing. That is, in step (C-2), the alloying furnace 33, located downstream of the hot-dip galvanizing bath 31 and the gas wiping device 32 in the plate-passing direction, performs heating and alloying for hot-dip galvanizing. The alloying treatment can be carried out using conventional methods. The heating method in the alloying furnace 33 is not particularly limited; examples include heating with high-temperature gas and induction heating. The alloying furnace 33 is any equipment in the CGL, and the alloying process is any process in the manufacturing method of the steel sheet using the CGL.

[0100] (Cooling device)

[0101] Reference Figure 2 , 3The cooling device 34 is located downstream of the gas wiping device 32 and the alloying furnace 33 in the direction of the through plate. It allows the cold-rolled steel sheet S to be cooled through the through plate in the cooling device 34. The cooling device 34 cools the cold-rolled steel sheet S through water cooling, air cooling, gas cooling, mist cooling, etc.

[0102] Tension winding machine

[0103] [Process (D)]

[0104] Reference Figures 1-3 The cold-rolled steel sheet S from downstream equipment 30 is finally wound into product coil P by tension winding machine 50, which serves as a winding device.

[0105] [Vibration attachment device and vibration attachment process]

[0106] It is important that the CAL100 of the first embodiment, CGL200 of the second embodiment, and CGL300 of the third embodiment described above have a vibration addition device 60 or 70 for adding vibration to the cold-rolled steel sheet S passing through the cooling strip 26 to the tension coiler 50. That is, it is important that the steel sheet manufacturing methods of the first, second, and third embodiments include a vibration addition step for adding vibration to the cold-rolled steel sheet S in the passing strip after step (B-2) and before step (D). Furthermore, it is important that the vibration frequency of the cold-rolled steel sheet S added by the vibration addition device 60 or 70 is 100Hz to 100,000Hz and the maximum amplitude of the cold-rolled steel sheet S is 10nm to 500μm. This allows for a sufficiently efficient reduction of hydrogen content in the cold-rolled steel sheet S during annealing, enabling the manufacture of steel sheets with excellent resistance to hydrogen embrittlement. Furthermore, the vibration addition is incorporated into the manufacturing process (production line) of CAL100, CGL200, or CGL300 steel plates, thus not compromising production efficiency. Additionally, since hydrogen removal is achieved through vibration rather than heating, there is no concern about altering the mechanical properties of the steel plates.

[0107] (Vibration attachment 60)

[0108] Various embodiments of the present invention can be achieved by, for example, Figure 4 The vibration attachment device 60 shown is implemented in CAL100, CGL200, or CGL300. The vibration attachment process uses this device 60 to apply vibration to the cold-rolled steel sheet S in the through-plate. (Refer to...) Figure 4 The vibration auxiliary device 60 includes a controller 61, an amplifier 62, an electromagnet 63, a vibration detector 64, and a power supply 65. (See reference...) Figure 6(A) and (B), the vibration attachment 60 has an electromagnet 63 comprising a magnet 63A and a coil 63B wound around the magnet 63A. The electromagnet 63 has a magnetic pole face 63A1 that is separately opposed to the surface of the cold-rolled steel sheet S. The vibration attachment 60 is configured to cause the cold-rolled steel sheet S to vibrate by an external force (attraction force) applied to the cold-rolled steel sheet S by the electromagnet 63.

[0109] As long as the electromagnet 63 has a magnetic pole face 63A1 that is separated from the surface of the cold-rolled steel sheet S, its shape and arrangement are not limited. Thus, as Figure 6 As shown in (A) and (B), the direction of the magnetic field lines is perpendicular to the cold-rolled steel sheet S, enabling it to exert an attractive force on the cold-rolled steel sheet S. Examples of the shape and arrangement of the electromagnet include, for instance... Figure 5 (A) (B).

[0110] exist Figure 5 In (A), a cuboid electromagnet 63 extends along the width direction of the cold-rolled steel sheet S at a predetermined interval from the surface of the sheet. This allows for the uniform application of an external force (attraction force) along the width direction of the surface of the cold-rolled steel sheet S, achieving uniform vibration in the width direction. Furthermore, by arranging multiple such electromagnets 63 along the through-plate direction, the duration of the applied vibration to the cold-rolled steel sheet S can be sufficiently ensured. Figure 5 As shown in (A), the electromagnet 63 has a magnet 63A and a coil 63B wound around it, the axis of which preferably aligns 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, such as Figure 6 As shown in (A), the magnetic pole face 63A1 opposite to the cold-rolled steel sheet S becomes the N pole, or as... Figure 6 As shown in (B), the magnetic pole face 63A1 opposite to the cold-rolled steel plate S becomes the S pole.

[0111] exist Figure 5 In (B), multiple cylindrical electromagnets 63 are arranged at predetermined intervals along the width direction of the cold-rolled steel sheet S, with their bottom magnetic pole surfaces facing away from the surface of the sheet. This allows for the uniform application of an external force (attraction force) along the width direction of the surface of the cold-rolled steel sheet S, achieving uniform vibration in the width direction. Furthermore, by arranging a row of multiple such cylindrical electromagnets 63 along the through-plate direction, sufficient time for applying vibration to the cold-rolled steel sheet S can be ensured. Figure 5 As shown in (B), each electromagnet 63 has a cylindrical magnet and a coil wound around it, the axis of which is aligned 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, as... Figure 6 As shown in (A), the magnetic pole face 63A1 opposite to the cold-rolled steel sheet S becomes the N pole, or as... Figure 6As shown in (B), the magnetic pole face 63A1 opposite to the cold-rolled steel plate S becomes the S pole.

[0112] exist Figure 6 (A) and Figure 6 In case (B), by allowing current to flow through electromagnet 63, an external force (attraction force) acts on the cold-rolled steel sheet S. The current flowing through electromagnet 63 can be a direct current pulse or an alternating current continuous current. When a direct current pulse flows through electromagnet 63, the attraction force acts intermittently on the cold-rolled steel sheet S, causing it to vibrate. When an alternating current continuous current flows through electromagnet 63, the magnetic pole face 63A1 opposite to the cold-rolled steel sheet S switches between the N and S poles each time the current direction changes, but the external force (attraction force) always acts on the cold-rolled steel sheet S. In the case of alternating current, the magnitude of the external force (attraction force) acting on the cold-rolled steel sheet S also changes according to the time-varying current value, thus causing the cold-rolled steel sheet S to vibrate.

[0113] It should be noted that the electromagnet 63 can be positioned opposite one surface of the cold-rolled steel sheet S, but it can also be positioned opposite both the surface and the back side. However, in this case, it is preferable to stagger the height positions so that the electromagnet on one side is not at the same height as the electromagnet on the other side.

[0114] Figure 4 The vibration detector 64 shown can be a laser displacement meter or a laser Doppler vibrometer configured at a predetermined interval from the surface of the cold-rolled steel sheet S, and can measure the frequency and amplitude of the vibration of the cold-rolled steel sheet S. By configuring the vibration detector 64 at the same height position as the electromagnet 63 of the cold-rolled steel sheet S, the maximum amplitude of the vibration of the cold-rolled steel sheet S can be measured using the vibration detector 64. 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 the set values, performs PID calculations on the deviations, etc., to determine the frequency (frequency of DC pulse current or frequency of AC continuous current) and current value of the electromagnet 63 so that the cold-rolled steel sheet S vibrates at a predetermined frequency and maximum amplitude. In addition, considering the amplification of the amplifier 62, the current value supplied to the amplifier 62 is determined, and a command value is provided to the power supply 65. The power supply 65 is a power source for allowing current to flow through the coil of the electromagnet 63, receives the command value input from the controller 61, and provides a current with a predetermined frequency and current value to the amplifier 62. Amplifier 62 amplifies the current value supplied from power supply 65 at a specified amplification rate, providing a command value to electromagnet 63. As a result, a current with a specified frequency and current value flows through electromagnet 63, enabling the cold-rolled steel sheet S to vibrate at a specified frequency and maximum amplitude.

[0115] (Vibration attachment 70)

[0116] Various embodiments of the present invention can be achieved by, for example, Figure 7A The vibration attachment device 70 shown is implemented in CAL100, CGL200, or CGL300. The vibration attachment process uses this device 70 to apply vibration to the cold-rolled steel sheet S in the through-plate. (Refer to...) Figure 7A The vibration attachment 70 includes a controller 71, an oscillator 72, and a vibration detector 73. The vibration attachment 70 has an oscillator 72 that contacts the cold-rolled steel sheet S, and is configured to cause the cold-rolled steel sheet S to vibrate through the oscillator 72.

[0117] The oscillator 72 is not particularly limited as long as it is a general piezoelectric element, and its shape and arrangement are not limited, but for example... Figure 7B As shown, by making the flat plate-shaped vibrator 72 with the width direction of the plate as the long side into surface contact with the cold-rolled steel plate S, the cold-rolled steel plate S can be made to vibrate.

[0118] It should be noted that the oscillator 72 can be configured to contact one surface of the cold-rolled steel sheet S, but it can also be configured to contact both the surface and the back side. However, in this case, it is preferable to stagger the height positions so that the oscillator on one side is not at the same height position as the oscillator on the other side.

[0119] Figure 7A The vibration detector 73 shown can be a laser displacement meter or a laser Doppler vibrometer configured at a predetermined interval from the surface of the cold-rolled steel sheet S, capable of measuring the frequency and amplitude of the vibration of the cold-rolled steel sheet S. By configuring the vibration detector 73 at the same height as the oscillator 72 of the cold-rolled steel sheet S, the maximum amplitude of the vibration of the cold-rolled steel sheet S can be measured using 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 PID calculations on the deviations, etc., to determine the frequency and current value of the DC pulse current flowing through the oscillator 72 in a manner that causes the cold-rolled steel sheet S to vibrate at a predetermined frequency and maximum amplitude, and controls a power supply (not shown) to provide a DC pulse current of the predetermined frequency and current value to the oscillator 72. As a result, the oscillator 72 vibrates at a predetermined frequency and amplitude, thereby enabling the cold-rolled steel sheet S to vibrate at a predetermined frequency and maximum amplitude.

[0120] In the first, second, and third embodiments, the position of the vibration attachment 60 or 70 is not limited as long as it can provide additional vibration to the cold-rolled steel sheet S in the through-plate from the cooling belt 26 to the tension coiler 50.

[0121] Reference Figure 1The preferred location of the vibration attachment device 60 or 70, i.e., the preferred timing of the vibration attachment process, will be explained in the first embodiment for manufacturing product coils of cold-rolled annealed steel sheet (CR) using CAL100. As an example, the vibration attachment device 60 or 70 can be placed in the cooling zone 26. In this case, the vibration attachment process can be performed in process (B-2). Specifically, the vibration attachment device 60 or 70 can be placed between multiple cooling zones arranged along the steel sheet conveying path, and between cooling nozzles adjacent to each cooling zone along the steel sheet conveying path. Figure 4 The electromagnet 63 shown Figure 7A The oscillator 72 is shown in B. Figure 8 (A) and (B) show examples of the positional relationship between the cooling nozzle 26A and the vibration attachment 60 or 70 when the vibration attachment 60 or 70 is installed inside the cooling zone 26. It should be noted that the vibration attachment 60 or 70 does not need to be located entirely inside the cooling zone 26, at least the electromagnet 63 or the oscillator 72 needs to be located inside the cooling zone 26.

[0122] As another example, the vibration attachment 60 or 70 can be positioned to apply additional vibration to the cold-rolled steel sheet S in the downstream equipment 30 through-plate. In this case, the vibration attachment process can be performed in process (C). Specifically, the vibration attachment 60 or 70 can be installed in at least one of the following: (i) between the aging treatment strip 28 and the exit looper 35, (ii) within the exit looper 35, (iii) between the exit looper 35 and the leveling mill 36, and (iv) between the leveling mill 36 and the tension coiler 50.

[0123] The vibration attachment device 60 or 70 can be installed in both the cooling zone 26 and the location where additional vibration can be applied to the cold-rolled steel sheet S in the downstream equipment 30 through-plate. That is, the vibration attachment process can be performed in both process (B-2) and process (C). Alternatively, the vibration attachment device 60 or 70 can be installed in the over-aging treatment zone 28, where the vibration attachment process is performed during the over-aging treatment.

[0124] Next, refer to Figure 2 The preferred location of the vibration attachment device 60 or 70, i.e., the preferred timing of the vibration attachment process, will be explained in the second embodiment for manufacturing alloyed hot-dip galvanized steel sheet (GA) using CGL200. As an example, the vibration attachment device 60 or 70 can be positioned at a first location where vibration can be applied to the cold-rolled steel sheet S in the upstream plate of the hot-dip galvanizing bath 31. In this case, the vibration attachment process can be performed before process (C-1). Specifically, the vibration attachment device 60 or 70 can be positioned in the cooling zone 26. More specifically, it can be positioned between multiple cooling zones arranged along the steel sheet conveying path, and between cooling nozzles adjacent to each cooling zone along the steel sheet conveying path. Figure 4 The electromagnet 63 shown Figure 7A The oscillator 72 shown in Figure B. This embodiment also applies to... Figure 8 Examples are shown in (A) and (B). Furthermore, it is not necessary for the entire vibration attachment 60 or 70 to be located inside the cooling zone 26; at least the electromagnet 63 or the vibrator 72 may be located inside the cooling zone 26. Alternatively, at least the electromagnet 63 or the vibrator 72 of the vibration attachment 60 or 70 may be disposed within the nozzle 29.

[0125] As another example, the vibration attachment device 60 or 70 can be positioned at a second location capable of applying additional vibration to the cold-rolled steel sheet S in the downstream pass of the hot-dip galvanizing bath 31. In this case, the vibration attachment process can be performed after process (C-1). Specifically, the vibration attachment device 60 or 70 can be installed in at least one of the following: (i) between the hot-dip galvanizing bath 31 and the gas wiping device 32; (ii) between the gas wiping device 32 and the alloying furnace 33; (iii) inside the alloying furnace 33; (iv) in the air cooling zone between the alloying furnace 33 and the cooling device 34; (v) between the cooling device 34 and the exit looper 35; (vi) inside the exit looper 35; (vii) between the exit looper 35 and the leveling mill 36; and (viii) between the leveling mill 36 and the tension coiler 50. It is particularly preferred to install the vibration attachment device 60 or 70 in the air cooling zone of (iv).

[0126] From the viewpoint of ensuring more complete removal of hydrogen from the steel plate, the vibration application device 60 or 70 is preferably located in the first position rather than the second position. That is, the vibration application process is preferably performed before process (C-1) rather than after process (C-1). However, the vibration application device 60 or 70 may also be located in both the first and second positions. That is, the vibration application process may be performed both before and after process (C-1).

[0127] Next, refer to Figure 3 The preferred location of the vibration attachment device 60 or 70, i.e., the preferred timing of the vibration attachment process, will be explained in the third embodiment of manufacturing hot-dip galvanized steel sheet (GI) using CGL300. As an example, the vibration attachment device 60 or 70 can be positioned at a first location where vibration can be applied to the cold-rolled steel sheet S in the upstream plate of the hot-dip galvanizing bath 31. In this case, the vibration attachment process can be performed before process (C-1). Specifically, the vibration attachment device 60 or 70 can be positioned in the cooling zone 26. More specifically, it can be positioned between multiple cooling zones arranged along the steel sheet conveying path, and between cooling nozzles adjacent to each cooling zone along the steel sheet conveying path. Figure 4 The electromagnet 63 shown Figure 7AThe oscillator 72 shown in Figure B. This embodiment also applies to... Figure 8 Examples are shown in (A) and (B). Furthermore, it is not necessary for the entire vibration attachment 60 or 70 to be located inside the cooling zone 26; at least the electromagnet 63 or the vibrator 72 may be located inside the cooling zone 26. Alternatively, at least the electromagnet 63 or the vibrator 72 of the vibration attachment 60 or 70 may be disposed within the nozzle 29.

[0128] As another example, the vibration attachment device 60 or 70 can be positioned at a second location capable of applying additional vibration to the cold-rolled steel sheet S in the downstream pass of the hot-dip galvanizing bath 31. In this case, the vibration attachment process can be performed after process (C-1). Specifically, the vibration attachment device 60 or 70 can be installed in at least one of the following: (i) between the hot-dip galvanizing bath 31 and the gas wiping device 32; (ii) between the gas wiping device 32 and the cooling device 34; (iii) between the cooling device 34 and the exit looper 35; (iv) inside the exit looper 35; (v) between the exit looper 35 and the leveling mill 36; and (vi) between the leveling mill 36 and the tension coiler 50. It is particularly preferred to install the vibration attachment device 60 or 70 in the air cooling zone of (ii).

[0129] From the viewpoint of ensuring more complete removal of hydrogen from the steel plate, the vibration application device 60 or 70 is preferably located in the first position rather than the second position. That is, the vibration application process is preferably performed before process (C-1) rather than after process (C-1). However, the vibration application device 60 or 70 may also be located in both the first and second positions. That is, the vibration application process may be performed both before and after process (C-1).

[0130] (frequency of vibration)

[0131] From the viewpoint of promoting hydrogen diffusion, it is important that the vibration frequency of the cold-rolled steel sheet S is 100 Hz or higher. If the frequency is lower than 100 Hz, the effect of removing hydrogen contained in the cold-rolled steel sheet S cannot be achieved. From this viewpoint, the frequency is 100 Hz or higher, preferably 500 Hz or higher, and more preferably 1000 Hz or higher. It should be noted that the cold-rolled steel sheet S vibrates itself during its passage process, or vibrates, for example, by receiving gas from the gas wiping device 32. However, in these vibrations, the vibration frequency of the cold-rolled steel sheet S is as high as about 20 Hz, in which case the effect of removing hydrogen contained in the cold-rolled steel sheet S cannot be achieved. On the other hand, if the frequency is too high, sufficient time for the lattice spacing to expand within the steel sheet cannot be ensured, and the effect of hydrogen removal still cannot be achieved. From this viewpoint, it is important that the frequency is 100,000 Hz or lower, preferably 80,000 Hz or lower, and more preferably 50,000 Hz or lower. The vibration frequency of the cold-rolled steel sheet S can be adjusted by... Figure 4 Vibration detector 64 shown Figure 7A The vibration detector 73 shown is used for measurement. Additionally, the frequency of vibration of the cold-rolled steel sheet S is... Figure 4 In the case of the vibration auxiliary device 60 shown, the frequency can be adjusted by controlling the frequency of the DC pulse current or the frequency of the AC continuous current. Figure 7A In the case of the vibration attachment 70 shown in Figure B, the vibration frequency of the oscillator 72 can be adjusted by controlling the vibration frequency of the oscillator 72.

[0132] (Maximum amplitude of vibration)

[0133] When the maximum amplitude of the cold-rolled steel sheet S is less than 10 nm, the lattice spacing on the steel sheet surface does not sufficiently increase, and the promotion of hydrogen diffusion is insufficient, thus failing to achieve the effect of removing hydrogen contained in the cold-rolled steel sheet S. Therefore, it is important that the maximum amplitude of the cold-rolled steel sheet S is 10 nm or more, preferably 100 nm or more, and more preferably 500 nm or more. Furthermore, when the maximum amplitude of the cold-rolled steel sheet S exceeds 500 μm, the strain on the steel sheet surface increases, resulting in plastic deformation and hydrogen trapping, thus failing to achieve the effect of removing hydrogen contained in the cold-rolled steel sheet S. From this perspective, it is important that the maximum amplitude of the cold-rolled steel sheet S is 500 μm or less, preferably 400 μm or less, and more preferably 300 μm or less. It should be noted that the cold-rolled steel sheet S vibrates itself during its passing process, or vibrates, for example, by receiving gas from the gas wiping device 32. However, in these vibrations, the maximum amplitude of the cold-rolled steel sheet S is at least 0.5 mm, thus failing to achieve the effect of removing hydrogen contained in the cold-rolled steel sheet S. The maximum amplitude of cold-rolled steel sheet S can be achieved through Figure 4 Vibration detector 64 shown Figure 7A The vibration detector 73 shown is used for measurement. Additionally, for the maximum amplitude of the cold-rolled steel sheet S, in Figure 4 In the case of the vibration auxiliary device 60 shown, the vibration can be adjusted by controlling the amount of current flowing through the electromagnet 63. Figure 7A In the case of the vibration attachment 70 shown in B, the amplitude of the vibration of the oscillator 72 can be adjusted by controlling the vibration amplitude.

[0134] (Vibration with added time)

[0135] From the viewpoint of more fully reducing hydrogen from the cold-rolled steel sheet S, the additional vibration time applied to the cold-rolled steel sheet S during the vibration application process is preferably 1 second or more, more preferably 5 seconds or more, and even more preferably 10 seconds or more. On the other hand, from the viewpoint of not hindering productivity, the additional vibration time applied to the cold-rolled steel sheet S is preferably 3600 seconds or less, more preferably 1800 seconds or less, and even more preferably 900 seconds or less. In this specification, "the additional vibration time applied to the cold-rolled steel sheet S" refers to the time for applying vibration to each position on the surface of the cold-rolled steel sheet S; when vibrations from multiple vibration application devices 60 or 70 are applied to each position, it refers to this cumulative time. (Refer to...) Figure 6 (A) and (B), when using the vibration attachment 60, the portion of the surface of the cold-rolled steel sheet S facing the electromagnet 63 can be considered to be vibrating. Therefore, the cumulative time for each part of the cold-rolled steel sheet S to be facing the electromagnet 63 can be considered as the vibration attachment time. When using... Figure 7A In the case of the vibration attachment device 70 shown in Figure B, the cumulative contact time between each part of the cold-rolled steel sheet S and the vibrator 72 can be used as the vibration attachment time. The vibration attachment time can be determined by the passing speed of the cold-rolled steel sheet S and the position of the vibration attachment device 60 or 70 (e.g., ...). Figure 4 The number of electromagnets 63 shown along the through plate direction Figure 7A Adjust the number of oscillators 72 (shown in B) along the direction of the through plate.

[0136] Cold-rolled steel sheet

[0137] In this embodiment, the cold-rolled steel sheet S supplied to CAL100, CGL200, and CGL300 is not particularly limited. The cold-rolled steel sheet S is preferably less than 6 mm thick, and examples include high-strength steel sheets and stainless steel sheets with a tensile strength of 590 MPa or more.

[0138] [Composition of cold-rolled steel sheet: high-strength steel sheet]

[0139] The composition of cold-rolled steel sheet S is explained when it is a high-strength steel sheet. Hereinafter, "mass %" will be abbreviated as "%".

[0140] C: 0.030~0.800%

[0141] Carbon (C) has the effect of increasing the strength of steel plates. From the viewpoint of achieving this effect, the amount of C is 0.030% or more, preferably 0.080% or more. However, when the amount of C is excessive, the steel plate becomes significantly embrittled regardless of the hydrogen content. Therefore, the amount of C is 0.800% or less, preferably 0.500% or less.

[0142] Si: 0.01~3.00%

[0143] Si has the effect of improving the strength of steel sheets. From the viewpoint of achieving this effect, the Si content is 0.01% or more, preferably 0.10% or more. However, if the Si content is excessive, the steel sheet will become brittle, resulting in reduced ductility, or a red oxide scale will form, leading to deterioration of surface properties, or a reduction in coating quality. Therefore, the Si content is 3.00% or less, preferably 2.50% or less.

[0144] Mn: 0.01~10.00%

[0145] Mn has the effect of improving the strength of steel plates through solid solution strengthening. From the viewpoint of achieving this effect, the Mn content is 0.01% or more, preferably 0.5% or more. However, when the Mn content is excessive, Mn segregation can sometimes easily lead to inhomogeneity in the steel microstructure, making hydrogen embrittlement, starting from this inhomogeneity, more pronounced. Therefore, the Mn content is 10.00% or less, preferably 8.00% or less.

[0146] P: 0.001~0.100%

[0147] P is an element that provides solid solution strengthening and can be added according to the desired strength. From the viewpoint of achieving this effect, the amount of P is 0.001% or more, preferably 0.003% or more. However, in cases of excessive P, weldability deteriorates, and in the case of alloying galvanizing, the alloying rate decreases, resulting in compromised galvanizing quality. Therefore, the amount of P is 0.100% or less, preferably 0.050% or less.

[0148] S: 0.0001~0.0200%

[0149] Sulfur (S) segregates at grain boundaries, causing steel to become embrittled during hot working, and its presence as sulfides reduces local deformation capacity. Therefore, the amount of S is 0.0200% or less, preferably 0.0100% or less, and more preferably 0.0050% or less. On the other hand, considering production technology limitations, the amount of S is 0.0001% or more.

[0150] N: 0.0005~0.0100%

[0151] Nitrogen (N) is an element that degrades the aging resistance of steel. Therefore, the amount of N is 0.0100% or less, preferably 0.0070% or less. Lower N content is preferred, but considering production technology constraints, the amount of N is 0.0005% or more, preferably 0.0010% or more.

[0152] Al: 0.001~2.000%

[0153] Al is an element that functions as a deoxidizer and is effective in improving the cleanliness of steel. From the viewpoint of achieving this effect, the Al content is 0.001% or more, preferably 0.010% or more. However, if the Al content is excessive, steel sheet cracks may occur during continuous casting. Therefore, the Al content is 2.000% or less, preferably 1.200% or less.

[0154] The remainder, other than the components mentioned above, consists of Fe and unavoidable impurities. However, it may contain any element selected from at least one of the following.

[0155] Ti: below 0.200%

[0156] Ti contributes to the improvement of steel sheet strength through precipitation strengthening and fine-grain strengthening resulting from the inhibition of ferrite grain growth. Therefore, when adding Ti, the Ti content is preferably 0.005% or more, more preferably 0.010% or more. However, when the Ti content is excessive, a large amount of carbonitrides may precipitate, reducing formability. Therefore, when adding Ti, the Ti content is set to 0.200% or less, preferably 0.100% or less.

[0157] Nb: below 0.200%, V: below 0.500%, W: below 0.500%

[0158] Nb, V, and W are effective for precipitation strengthening of steel. Therefore, when Nb, V, and W are added, the content of each element is preferably 0.005% or more, more preferably 0.010% or more. However, when the content of each element is excessive, carbonitrides may precipitate in large quantities, reducing formability. Therefore, when Nb is added, the amount of Nb is 0.200% or less, preferably 0.100% or less. When V and W are added, the content of each element is 0.500% or less, preferably 0.300% or less.

[0159] B: Below 0.0050%

[0160] Boron (B) is effective in strengthening grain boundaries and increasing the strength of steel sheets. Therefore, when adding B, the amount of B is preferably 0.0003% or more. However, when the amount of B is excessive, the formability may sometimes decrease. Therefore, when adding B, the amount of B is 0.0050% or less, preferably 0.0030% or less.

[0161] Ni: below 1.000%

[0162] Ni is an element that increases the strength of steel through solid solution strengthening. Therefore, when adding Ni, the Ni content is preferably 0.005% or more. However, if the Ni content is excessive, the area fraction of hard martensite becomes too large, and during tensile testing, the microporosity at the martensite grain boundaries increases, cracks propagate, and sometimes ductility decreases. Therefore, when adding Ni, the Ni content is 1.000% or less.

[0163] Cr: less than 1.000%, Mo: less than 1.000%

[0164] Cr and Mo have a balancing effect on improving strength and formability. Therefore, when Cr and Mo are added, the content of each element is preferably 0.005% or more. However, when the content of each element is excessive, the area ratio of hard martensite becomes too large, and during tensile testing, the microporosity at the grain boundaries of the martensite increases, cracks propagate, and sometimes ductility decreases. Therefore, when Cr and Mo are added, the content of each element is 1.000% or less.

[0165] Cu: below 1.000%

[0166] Cu is an effective strengthening element for steel. Therefore, when adding Cu, the Cu content is preferably 0.005% or more. However, if the Cu content is excessive, the area fraction of hard martensite becomes too large, and during tensile testing, microporosity at the grain boundaries of tempered martensite increases, crack propagation occurs, and sometimes ductility decreases. Therefore, when adding Cu, the Cu content is 1.000% or less.

[0167] Sn: less than 0.200%, Sb: less than 0.200%

[0168] Sn and Sb are effective in suppressing decarburization in the surface layer of steel plates (approximately tens of μm) caused by nitriding and oxidation, thus ensuring strength and material stability. Therefore, when Sn and Sb are added, the content of each element is preferably 0.002% or more. However, excessive amounts of either element can sometimes reduce toughness. Therefore, when Sn and Sb are added, the content of each element is 0.200% or less.

[0169] Ta: below 0.100%

[0170] Like Ti and Nb, Ta forms alloy carbides and alloy carbonitrides, contributing to increased strength. Furthermore, it is believed that a portion of Ta dissolves in Nb carbides and Nb carbonitrides, forming composite precipitates such as (Nb,Ta)(C,N), which significantly suppresses precipitate coarsening and stabilizes the strength-enhancing effect of precipitation strengthening. Therefore, when Ta is added, the Ta content is preferably 0.001% or more. However, even with excessive Ta addition, the precipitate stabilization effect sometimes becomes saturated, and the alloy cost increases. Therefore, when Ta is added, the Ta content is 0.100% or less.

[0171] Ca: below 0.0050%, Mg: below 0.0050%, Zr: below 0.1000%, REM (Rare Earth Metal): below 0.0050%

[0172] Ca, Mg, Zr, and REM are effective elements for shaping sulfides into spherical forms and improving their adverse effects on moldability. When these elements are added, the content of each element is preferably 0.0005% or more. However, excessive amounts of any of these elements can sometimes increase inclusions and other defects, leading to surface and internal defects. Therefore, when these elements are added, the content of each element is 0.0050% or less.

[0173] [Composition of cold-rolled steel sheet: Stainless steel sheet]

[0174] The composition of the cold-rolled steel sheet S is explained when it is stainless steel. Hereinafter, "mass %" is abbreviated as "%".

[0175] C: 0.001~0.400%

[0176] C is an essential element for achieving high strength in stainless steel. However, during tempering in steelmaking, it combines with Cr and precipitates as carbides, which degrades the steel's corrosion resistance and toughness. If the C content is less than 0.001%, sufficient strength cannot be obtained, and if it exceeds 0.400%, the aforementioned degradation becomes significant. Therefore, the optimal C content is 0.001% to 0.400%.

[0177] Si: 0.01~2.00%

[0178] Si is a useful element as a deoxidizer. From the viewpoint of achieving this effect, the Si content should be 0.01% or higher. However, in the case of excessive Si, the Si dissolved in the steel reduces the steel's workability. Therefore, the Si content should be 2.00% or lower.

[0179] Mn: 0.01~5.00%

[0180] Mn has the effect of increasing the strength of steel. From the viewpoint of achieving this effect, the Mn content should be 0.01% or more. However, if the Mn content is excessive, the workability of the steel decreases. Therefore, the Mn content should be 5.00% or less.

[0181] P: 0.001~0.100%

[0182] Phosphorus (P) is an element that promotes grain boundary destruction due to grain boundary segregation. Therefore, a lower P content is preferred, preferably 0.100% or less, more preferably 0.030% or less, and even more preferably 0.020% or less. On the other hand, considering production technology constraints, a P content of 0.001% or more is preferable.

[0183] S: 0.0001~0.0200%

[0184] Sulfide (S) exists as an inclusion in sulfide systems such as MnS, reducing ductility and corrosion resistance. Therefore, a lower S content is preferred, preferably 0.0200% or less, more preferably 0.0100% or less, and even more preferably 0.0050% or less. On the other hand, considering production technology limitations, an S content of 0.0001% or more is acceptable.

[0185] Cr: 9.0–28.0%

[0186] Cr is a fundamental element in stainless steel and therefore a crucial element in demonstrating its corrosion resistance. When considering corrosion resistance in harsh environments above 180°C, insufficient corrosion resistance cannot be achieved if the Cr content is less than 9.0%, while exceeding 28.0% results in saturation, posing an economic challenge. Therefore, the Cr content is typically between 9.0% and 28.0%.

[0187] Ni: 0.01~40.0%

[0188] Ni is an element that improves the corrosion resistance of stainless steel. If the Ni content is less than 0.01%, this effect cannot be fully realized. On the other hand, excessive Ni content deteriorates formability and easily leads to stress corrosion cracking. Therefore, the Ni content should be between 0.01% and 40.0%.

[0189] N: 0.0005~0.500%

[0190] Nitrogen (N) is an element that negatively impacts the corrosion resistance of stainless steel. Therefore, the N content should be 0.500% or less, preferably 0.200% or less. Lower N content is preferred, but considering production technology limitations, a N content of 0.0005% or more is preferable.

[0191] Al: 0.001~3.000%

[0192] Al acts as a deoxidizer and also inhibits oxide scale peeling. From the viewpoint of achieving these effects, an Al content of 0.001% or higher is recommended. However, excessive Al content leads to decreased elongation and deterioration of surface quality. Therefore, an Al content of 3.000% or lower is preferred.

[0193] The remainder besides the above-mentioned components is Fe and unavoidable impurities. However, it may arbitrarily contain at least one element selected from the following.

[0194] Ti: below 0.500%

[0195] Ti combines with C, N, and S to improve corrosion resistance, resistance to intergranular corrosion, and deep-drawing properties. However, when the Ti content exceeds 0.500%, the toughness deteriorates through solid solution treatment of Ti. Therefore, when adding Ti, the Ti content should be below 0.500%.

[0196] Nb: below 0.500%

[0197] Like Ti, Nb combines with C, N, and S to improve corrosion resistance, resistance to intergranular corrosion, and deep-drawing properties. In addition to improving processability and high-temperature strength, it also promotes the suppression of crevice corrosion and repassivation. However, excessive addition leads to hardening and deteriorates formability. Therefore, when adding Nb, the amount should be below 0.500%.

[0198] V: Below 0.500%

[0199] V inhibits crevice corrosion. However, excessive addition degrades formability. Therefore, when adding V, the amount should be below 0.500%.

[0200] W: Below 2.000%

[0201] W contributes to improved corrosion resistance and high-temperature strength. However, excessive addition leads to decreased toughness and increased costs during steel plate manufacturing. Therefore, when adding W, the amount should be below 2.000%.

[0202] B: Below 0.0050%

[0203] Boron (B) improves the secondary processability of products through grain boundary segregation. However, excessive addition leads to a decrease in processability and corrosion resistance. Therefore, when adding B, the amount should be below 0.0050%.

[0204] Mo: 2.000% or less

[0205] Mo is an element that improves corrosion resistance, especially inhibiting crevice corrosion. However, excessive addition deteriorates formability. Therefore, when adding Mo, the amount should be below 2.000%.

[0206] Cu: below 3.000%

[0207] Like Ni and Mn, Cu is an austenite stabilizing element, effective in refining grains due to phase transformation. It also promotes the suppression and re-passivation of interstitial corrosion. However, excessive addition degrades toughness and formability. Therefore, when adding Cu, the Cu content should be below 3.000%.

[0208] Sn: below 0.500%

[0209] Sn contributes to improved corrosion resistance and high-temperature strength. However, excessive addition may cause slab cracking during steel sheet manufacturing. Therefore, when adding Sn, the amount should be below 0.500%.

[0210] Sb: below 0.200%

[0211] Sb can improve high-temperature strength by segregating at grain boundaries. However, excessive addition may cause cracks during welding due to Sb segregation. Therefore, when adding Sb, the amount should be below 0.200%.

[0212] Ta: below 0.100%

[0213] Ta combines with C and N to improve toughness. However, excessive addition saturates this effect, leading to increased manufacturing costs. Therefore, when adding Ta, the amount should be below 0.100%.

[0214] Ca: below 0.0050%, Mg: below 0.0050%, Zr: below 0.1000%, REM (Rare Earth Metal): below 0.0050%

[0215] Ca, Mg, Zr, and REM are effective elements for shaping sulfides into spherical forms and improving their adverse effects on moldability. When these elements are added, the content of each element is preferably 0.0005% or more. However, excessive amounts of any of these elements can sometimes increase inclusions and other defects, leading to surface and internal defects. Therefore, when these elements are added, the content of each element is 0.0050% or less.

[0216] [Diffusible hydrogen content]

[0217] In this embodiment, to ensure good flexibility, the diffusible hydrogen content of the product roll is preferably 0.50 ppm by mass or less, more preferably 0.30 ppm by mass or less, and even more preferably 0.20 ppm by mass or less. It should be noted that there is no particular lower limit for the diffusible hydrogen content of the product roll, but considering the limitations of production technology, the diffusible hydrogen content of the product roll can be 0.01 ppm by mass or more.

[0218] Here, the method for determining the diffusive hydrogen content of the product coil is as follows. A test piece with a length of 30 mm and a width of 5 mm is taken from the product coil. In the case of product coils made of hot-dip galvanized steel sheet or 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 treatment. Then, the amount of hydrogen released from the test piece is determined by thermal desorption spectrometry (TDS). Specifically, the test piece is continuously heated from room temperature to 300°C at a heating rate of 200°C / h, then cooled to room temperature, and the cumulative amount of hydrogen released from the test piece from room temperature to 210°C is measured to obtain the diffusive hydrogen content of the product coil.

[0219] Example

[0220] Steel with a composition containing the elements shown in Table 1, with the remainder consisting of Fe and unavoidable impurities, is smelted in a converter and produced into slabs using continuous casting. The resulting slabs are then hot-rolled and cold-rolled to obtain cold-rolled coils. As shown in Table 2, in a portion of the process, using… Figure 1 The product coils shown are manufactured by CAL using cold-rolled annealed steel sheets (CR), and in other levels, utilize... Figure 2 The CGL shown manufactures hot-dip galvanized steel sheet (GI) coils without heat alloying, while in other levels, it utilizes... Figure 2 The product shown is a coil of CGL-manufactured alloyed hot-dip galvanized steel sheet (GA).

[0221] According to each level, use Figures 4-6 The electromagnetic vibration attachment device shown applies vibration to the cold-rolled steel sheet in the through-plate under the conditions of maximum amplitude, frequency, and vibration attachment time shown in Table 2. The "Vibration Attachment Location" in Table 2 indicates the area where the CAL or CGL vibration attachment process is performed, i.e., the location where the vibration attachment device is installed.

[0222] "(B-2)" refers to the installation of a vibration auxiliary device in the cooling belt of CAL and CGL, and the use of the cooling belt of process (B-2) for vibration auxiliary process.

[0223] "(C)" refers to the installation of a vibration-assisted device in the CAL at a location capable of adding vibration to the cold-rolled steel sheet in the downstream equipment pass-through. Specifically, it refers to at least one of the following locations: downstream of the cooling belt and upstream of the tension coiler: (i) between the over-aging treatment belt 28 and the exit looper 35; (ii) inside the exit looper 35; (iii) between the exit looper 35 and the leveling mill 36; and (iv) between the leveling mill 36 and the tension coiler 50. That is, "(C)" refers to the vibration-assisted process being performed in the CAL during process (C), specifically at at least one of the locations (i) to (iv) mentioned above.

[0224] "(C-1) before" refers to the location in CGL downstream of the cooling zone and upstream of the hot-dip galvanizing bath, specifically at nozzle 29, where a vibration additional device is installed, and the vibration additional process is performed after process (B-2) and before process (C-1).

[0225] "(C-1) after" means that a vibration additional device is installed in CGL at a position downstream of the hot-dip galvanizing bath and upstream of the tension coiler, specifically at at least one of the following positions: (i) between the hot-dip galvanizing bath 31 and the gas wiping device 32, (ii) between the gas wiping device 32 and the alloying furnace 33, (iii) inside the alloying furnace 33, (iv) the air cooling zone between the alloying furnace 33 and the cooling device 34, (v) between the cooling device 34 and the outlet looper 35, (vi) inside the outlet looper 35, (vii) between the outlet looper 35 and the leveling mill 36, and (viii) between the leveling mill 36 and the tension coiler 50. The vibration additional process is performed after process (C-1), specifically at at least one of the positions (i) to (viii) above.

[0226] Samples of steel plates were taken from the product coils obtained from each level, and their tensile properties and resistance to hydrogen embrittlement were evaluated as follows. The results are shown in Table 2.

[0227] The tensile test was conducted using JIS 5 test pieces taken with the tensile direction perpendicular to the rolling direction of the steel plate, in accordance with JIS Z 2241 (2011), to determine TS (tensile strength) and EL (total elongation).

[0228] The hydrogen embrittlement resistance was evaluated based on the tensile test described above. A value of 0.70 or higher obtained by dividing the EL of the vibrated steel plate (measured above) by EL' when the hydrogen content in the same steel plate is 0.00 ppm by mass is considered good hydrogen embrittlement resistance. It should be noted that EL' is determined by placing the same steel plate in the atmosphere for an extended period to reduce the internal hydrogen content, then confirming the hydrogen content in the steel to be 0.00 ppm by mass using TDS before performing a tensile test.

[0229] The diffusible hydrogen content of the product rolls obtained at each level was determined according to the method described above, and the results are shown in Table 2.

[0230] In this invention, since a vibration-assisted process was performed under specified frequency and maximum amplitude conditions, it is possible to manufacture a steel plate with excellent resistance to hydrogen embrittlement.

[0231]

[0232]

[0233]

[0234] Industrial availability

[0235] According to the continuous annealing apparatus and continuous hot-dip galvanizing apparatus of the present invention, as well as the method for manufacturing steel plates, steel plates with excellent resistance to hydrogen embrittlement can be manufactured without compromising production efficiency or altering mechanical properties.

[0236] Symbol Explanation

[0237] 100 Continuous Annealing Unit

[0238] 200 Continuous Hot-Dip Galvanizing Unit

[0239] 300 Continuous Hot-Dip Galvanizing Unit

[0240] 10 Unwinding Machine

[0241] 11 Welding Machine

[0242] 12 Cleaning equipment

[0243] 13. Entrance Loop

[0244] 20 Annealing Furnace

[0245] 22 Heating belt

[0246] 24 tropical

[0247] 26 Cooling strip

[0248] 26A Cooling Nozzle

[0249] 28 Expired processing belt

[0250] 29 nozzles

[0251] 30 Downstream Equipment

[0252] 31 Hot-dip galvanizing bath

[0253] 32 Gas wiping device

[0254] 33 Alloying Furnace

[0255] 34 Cooling device

[0256] 35 Export Loop

[0257] 36 Leveling Rolling Mill

[0258] 50 tension winding machine

[0259] 60 Vibration Addition Device

[0260] 61 Controller

[0261] 62 Amplifier

[0262] 63 Electromagnet

[0263] 63A magnet

[0264] 63A1 Magnetic Pole Face

[0265] 63B coil

[0266] 64 Vibration Detector

[0267] 65 power supply

[0268] 70 Vibration Addition Device

[0269] 71 Controller

[0270] 72 Oscillators

[0271] 73 Vibration Detector

[0272] C Cold-rolled coil

[0273] S cold-rolled steel sheet

[0274] P Product Roll Material

Claims

1. A continuous annealing apparatus, comprising: The unwinding machine releases cold-rolled steel sheets from cold-rolled coils; An annealing furnace is used to continuously anneal the cold-rolled steel sheet by passing it through the plate. The annealing furnace is provided with a heating zone, a soaking zone and a cooling zone on the upstream side from the plate passage direction. The cold-rolled steel sheet is annealed in a reducing atmosphere containing hydrogen in the heating zone and the soaking zone, and the cold-rolled steel sheet is cooled in the cooling zone. Downstream equipment allows the cold-rolled steel sheet discharged from the annealing furnace to continue passing through the furnace; A tension coiler winds the cold-rolled steel sheet in the downstream equipment through-plate; and A vibration attachment device is used to apply vibration to the cold-rolled steel sheet passing through the cooling belt and the tension coiler in such a way that the frequency of the cold-rolled steel sheet is 100Hz to 100000Hz and the maximum amplitude of the cold-rolled steel sheet is 10nm to 500μm. The vibration auxiliary device is disposed on the cooling zone.

2. The continuous annealing apparatus according to claim 1, wherein, The vibration attachment is also positioned to apply additional vibration to the cold-rolled steel sheet in the downstream equipment through-plate.

3. The continuous annealing apparatus according to claim 1, wherein, The configuration of the vibration attachment device and the through speed of the cold-rolled steel sheet are set such that the additional vibration applied to the cold-rolled steel sheet is more than 1 second.

4. The continuous annealing apparatus according to any one of claims 1 to 3, wherein, The vibration attachment includes an electromagnet having magnetic pole faces that are separately opposed to the surface of the cold-rolled steel sheet, configured to cause the cold-rolled steel sheet to vibrate by an external force applied to it by the electromagnet.

5. The continuous annealing apparatus according to any one of claims 1 to 3, wherein, The vibration attachment has an oscillator that contacts the cold-rolled steel sheet, and is configured to cause the cold-rolled steel sheet to vibrate via the oscillator.

6. A continuous hot-dip galvanizing apparatus, comprising: The unwinding machine releases cold-rolled steel sheets from cold-rolled coils; An annealing furnace is used to continuously anneal the cold-rolled steel sheet by passing it through the plate. The annealing furnace is provided with a heating zone, a soaking zone and a cooling zone on the upstream side from the plate passage direction. The cold-rolled steel sheet is annealed in a reducing atmosphere containing hydrogen in the heating zone and the soaking zone, and the cold-rolled steel sheet is cooled in the cooling zone. Downstream equipment allows the cold-rolled steel sheet discharged from the annealing furnace to continue passing through the furnace; A tension coiler winds the cold-rolled steel sheet in the downstream equipment through-plate; and A vibration attachment device is used to apply vibration to the cold-rolled steel sheet passing through the cooling belt and the tension coiler in such a way that the frequency of the cold-rolled steel sheet is 100Hz to 100000Hz and the maximum amplitude of the cold-rolled steel sheet is 10nm to 500μm. As the hot-dip galvanizing bath of the downstream equipment, it is located downstream of the annealing furnace in the direction of the through plate, and immerses the cold-rolled steel sheet to perform hot-dip galvanizing on the cold-rolled steel sheet; as well as The gas wiping device is located downstream of the through plate of the hot-dip galvanizing bath; The vibration-adding device is positioned at either or both of the locations that can add vibration to the cold-rolled steel sheet in the upstream pass-through plate of the hot-dip galvanizing bath and the locations that can add vibration to the cold-rolled steel sheet in the downstream pass-through plate of the gas wiping device.

7. The continuous hot-dip galvanizing apparatus according to claim 6, wherein, As the downstream equipment, there is an alloying furnace located downstream of the gas wiping device in the direction of the through plate, through which the cold-rolled steel sheet is passed to heat and alloy the hot-dip galvanized steel.

8. The continuous hot-dip galvanizing apparatus according to claim 6, wherein, The configuration of the vibration attachment device and the through speed of the cold-rolled steel sheet are set such that the additional vibration applied to the cold-rolled steel sheet is more than 1 second.

9. The continuous hot-dip galvanizing apparatus according to any one of claims 6 to 8, wherein, The vibration attachment includes an electromagnet having magnetic pole faces that are separately opposed to the surface of the cold-rolled steel sheet, configured to cause the cold-rolled steel sheet to vibrate by an external force applied to it by the electromagnet.

10. The continuous hot-dip galvanizing apparatus according to any one of claims 6 to 8, wherein, The vibration attachment has an oscillator that contacts the cold-rolled steel sheet, and is configured to cause the cold-rolled steel sheet to vibrate via the oscillator.

11. A method for manufacturing a steel plate, comprising the following steps in sequence: (A) The process of releasing cold-rolled steel sheets from cold-rolled coils using an unwinding machine; (B) The cold-rolled steel sheet is passed through an annealing furnace in which a heating zone, a soaking zone and a cooling zone are provided on the upstream side from the through plate direction, and the following continuous annealing process is performed: (B-1) the cold-rolled steel sheet is annealed in the heating zone and the soaking zone in a reducing atmosphere containing hydrogen, and (B-2) the cold-rolled steel sheet is cooled in the cooling zone. (C) The process of continuing to pass the cold-rolled steel sheet discharged from the annealing furnace; and (D) The process of winding the cold-rolled steel sheet using a tension coiler to produce product coils. After process (B-2) and before process (D), a vibration additional process is included: the cold-rolled steel sheet in the through plate is subjected to additional vibration in a manner in which the frequency of the cold-rolled steel sheet is 100Hz to 100000Hz and the maximum amplitude of the cold-rolled steel sheet is 10nm to 500μm. The vibration-assisted process is carried out in process (B-2).

12. The method for manufacturing a steel plate according to claim 11, wherein, The vibration-assisted process is also carried out in process (C).

13. A method for manufacturing a steel plate, comprising the following steps in sequence: (A) The process of releasing cold-rolled steel sheets from cold-rolled coils using an unwinding machine; (B) The cold-rolled steel sheet is passed through an annealing furnace in which a heating zone, a soaking zone and a cooling zone are provided on the upstream side from the through plate direction, and the following continuous annealing process is performed: (B-1) the cold-rolled steel sheet is annealed in the heating zone and the soaking zone in a reducing atmosphere containing hydrogen, and (B-2) the cold-rolled steel sheet is cooled in the cooling zone. (C) The process of continuing to pass the cold-rolled steel sheet discharged from the annealing furnace; and (D) The process of winding the cold-rolled steel sheet using a tension coiler to produce product coils; After process (B-2) and before process (D), a vibration additional process is included: the cold-rolled steel sheet in the through plate is subjected to additional vibration in a manner in which the frequency of the cold-rolled steel sheet is 100Hz to 100000Hz and the maximum amplitude of the cold-rolled steel sheet is 10nm to 500μm. Process (C) includes (C-1) immersing the cold-rolled steel sheet in a hot-dip galvanizing bath located downstream of the annealing furnace in the direction of the through plate, and performing hot-dip galvanizing on the cold-rolled steel sheet; and a gas wiping process, in which gas is sprayed onto the cold-rolled steel sheet from a gas wiping device located downstream of the hot-dip galvanizing bath in the direction of the through plate. The vibration additional process is performed either before process (C-1) or after the gas wiping process of process (C-1).

14. The method for manufacturing a steel plate according to claim 13, wherein, The process (C) following the process (C-1) includes the process (C-2): passing the cold-rolled steel sheet through an alloying furnace located downstream of the gas wiping device in the plate-passing direction to heat and alloy the hot-dip galvanizing.

15. The method for manufacturing a steel plate according to claim 13, wherein, In the vibration addition process, the additional vibration time applied to the cold-rolled steel sheet is set to more than 1 second.

16. The method for manufacturing the steel plate according to any one of claims 11 to 15, wherein, In the vibration addition process, the cold-rolled steel sheet is vibrated by an external force applied to it by an electromagnet having magnetic pole faces that are separated from the surface of the cold-rolled steel sheet.

17. The method for manufacturing the steel plate according to any one of claims 11 to 15, wherein, In the vibration addition process, the cold-rolled steel sheet is vibrated by an oscillator that comes into contact with the cold-rolled steel sheet.

18. The method for manufacturing the steel plate according to any one of claims 11 to 15, wherein, The cold-rolled steel sheet is a high-strength steel sheet with a tensile strength of over 590 MPa.

19. The method for manufacturing the steel plate according to any one of claims 11 to 15, wherein, The cold-rolled steel sheet has the following composition: by mass % C: 0.030-0.800%, Si: 0.01-3.00%, Mn: 0.01-10.00%, P: 0.001-0.100%, S: 0.0001-0.0200%, N: 0.0005-0.0100% and Al: 0.001-2.000%, with the remainder consisting of Fe and unavoidable impurities.

20. The method for manufacturing a steel plate according to claim 19, wherein, The composition further contains, by mass%, at least one element selected from Ti: less than 0.200%, Nb: less than 0.200%, V: less than 0.500%, W: less than 0.500%, B: less than 0.0050%, Ni: less than 1.000%, Cr: less than 1.000%, Mo: less than 1.000%, Cu: less than 1.000%, Sn: less than 0.200%, Sb: less than 0.200%, Ta: less than 0.100%, Ca: less than 0.0050%, Mg: less than 0.0050%, Zr: less than 0.1000%, and REM: less than 0.0050%.

21. The method for manufacturing the steel plate according to any one of claims 11 to 15, wherein, The cold-rolled steel sheet is a stainless steel sheet with the following composition, which, by mass%, contains C: 0.001–0.400%, Si: 0.01–2.00%, Mn: 0.01–5.00%, P: 0.001–0.100%, S: 0.0001–0.0200%, Cr: 9.0–28.0%, Ni: 0.01–40.0%, N: 0.0005–0.500%, and Al: 0.001–3.000%, with the remainder consisting of Fe and unavoidable impurities.

22. The method for manufacturing a steel plate according to claim 21, wherein, The composition further contains, by mass%, at least one element selected from Ti: less than 0.500%, Nb: less than 0.500%, V: less than 0.500%, W: less than 2.000%, B: less than 0.0050%, Mo: less than 2.000%, Cu: less than 3.000%, Sn: less than 0.500%, Sb: less than 0.200%, Ta: less than 0.100%, Ca: less than 0.0050%, Mg: less than 0.0050%, Zr: less than 0.1000%, and REM: less than 0.0050%.

23. The method for manufacturing the steel plate according to any one of claims 11 to 15, wherein, The product roll has a diffusible hydrogen content of less than 0.50 ppm by mass.

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