WO2014156085A1 - 厚鋼板の製造方法および製造設備 - Google Patents

厚鋼板の製造方法および製造設備 Download PDF

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Publication number
WO2014156085A1
WO2014156085A1 PCT/JP2014/001613 JP2014001613W WO2014156085A1 WO 2014156085 A1 WO2014156085 A1 WO 2014156085A1 JP 2014001613 W JP2014001613 W JP 2014001613W WO 2014156085 A1 WO2014156085 A1 WO 2014156085A1
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Prior art keywords
steel plate
thick steel
cooling
water
temperature
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PCT/JP2014/001613
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English (en)
French (fr)
Japanese (ja)
Inventor
雄太 田村
安達　健二
Original Assignee
Ｊｆｅスチール株式会社
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Application filed by Ｊｆｅスチール株式会社 filed Critical Ｊｆｅスチール株式会社
Priority to KR1020157025725A priority Critical patent/KR101691020B1/ko
Priority to CN201480018326.5A priority patent/CN105073293B/zh
Priority to EP14773154.1A priority patent/EP2979769B1/en
Publication of WO2014156085A1 publication Critical patent/WO2014156085A1/ja

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    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B21—MECHANICAL METAL-WORKING WITHOUT ESSENTIALLY REMOVING MATERIAL; PUNCHING METAL
    • B21B—ROLLING OF METAL
    • B21B45/00—Devices for surface or other treatment of work, specially combined with or arranged in, or specially adapted for use in connection with, metal-rolling mills
    • B21B45/02—Devices for surface or other treatment of work, specially combined with or arranged in, or specially adapted for use in connection with, metal-rolling mills for lubricating, cooling, or cleaning
    • B21B45/0203—Cooling
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B21—MECHANICAL METAL-WORKING WITHOUT ESSENTIALLY REMOVING MATERIAL; PUNCHING METAL
    • B21B—ROLLING OF METAL
    • B21B45/00—Devices for surface or other treatment of work, specially combined with or arranged in, or specially adapted for use in connection with, metal-rolling mills
    • B21B45/04—Devices for surface or other treatment of work, specially combined with or arranged in, or specially adapted for use in connection with, metal-rolling mills for de-scaling, e.g. by brushing
    • B21B45/08—Devices for surface or other treatment of work, specially combined with or arranged in, or specially adapted for use in connection with, metal-rolling mills for de-scaling, e.g. by brushing hydraulically
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B21—MECHANICAL METAL-WORKING WITHOUT ESSENTIALLY REMOVING MATERIAL; PUNCHING METAL
    • B21B—ROLLING OF METAL
    • B21B1/00—Metal-rolling methods or mills for making semi-finished products of solid or profiled cross-section; Sequence of operations in milling trains; Layout of rolling-mill plant, e.g. grouping of stands; Succession of passes or of sectional pass alternations
    • B21B1/22—Metal-rolling methods or mills for making semi-finished products of solid or profiled cross-section; Sequence of operations in milling trains; Layout of rolling-mill plant, e.g. grouping of stands; Succession of passes or of sectional pass alternations for rolling plates, strips, bands or sheets of indefinite length
    • B21B2001/225—Metal-rolling methods or mills for making semi-finished products of solid or profiled cross-section; Sequence of operations in milling trains; Layout of rolling-mill plant, e.g. grouping of stands; Succession of passes or of sectional pass alternations for rolling plates, strips, bands or sheets of indefinite length by hot-rolling
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B21—MECHANICAL METAL-WORKING WITHOUT ESSENTIALLY REMOVING MATERIAL; PUNCHING METAL
    • B21B—ROLLING OF METAL
    • B21B15/00—Arrangements for performing additional metal-working operations specially combined with or arranged in, or specially adapted for use in connection with, metal-rolling mills
    • B21B2015/0071—Levelling the rolled product
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B21—MECHANICAL METAL-WORKING WITHOUT ESSENTIALLY REMOVING MATERIAL; PUNCHING METAL
    • B21B—ROLLING OF METAL
    • B21B45/00—Devices for surface or other treatment of work, specially combined with or arranged in, or specially adapted for use in connection with, metal-rolling mills
    • B21B45/02—Devices for surface or other treatment of work, specially combined with or arranged in, or specially adapted for use in connection with, metal-rolling mills for lubricating, cooling, or cleaning
    • B21B45/0203—Cooling
    • B21B45/0209—Cooling devices, e.g. using gaseous coolants
    • B21B2045/0212—Cooling devices, e.g. using gaseous coolants using gaseous coolants
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B21—MECHANICAL METAL-WORKING WITHOUT ESSENTIALLY REMOVING MATERIAL; PUNCHING METAL
    • B21B—ROLLING OF METAL
    • B21B2261/00—Product parameters
    • B21B2261/20—Temperature
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B21—MECHANICAL METAL-WORKING WITHOUT ESSENTIALLY REMOVING MATERIAL; PUNCHING METAL
    • B21B—ROLLING OF METAL
    • B21B37/00—Control devices or methods specially adapted for metal-rolling mills or the work produced thereby
    • B21B37/74—Temperature control, e.g. by cooling or heating the rolls or the product
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B21—MECHANICAL METAL-WORKING WITHOUT ESSENTIALLY REMOVING MATERIAL; PUNCHING METAL
    • B21B—ROLLING OF METAL
    • B21B45/00—Devices for surface or other treatment of work, specially combined with or arranged in, or specially adapted for use in connection with, metal-rolling mills
    • B21B45/02—Devices for surface or other treatment of work, specially combined with or arranged in, or specially adapted for use in connection with, metal-rolling mills for lubricating, cooling, or cleaning
    • B21B45/0203—Cooling
    • B21B45/0209—Cooling devices, e.g. using gaseous coolants
    • B21B45/0215—Cooling devices, e.g. using gaseous coolants using liquid coolants, e.g. for sections, for tubes
    • B21B45/0218—Cooling devices, e.g. using gaseous coolants using liquid coolants, e.g. for sections, for tubes for strips, sheets, or plates

Definitions

  • the present invention relates to a manufacturing method and manufacturing equipment for a thick steel plate.
  • the application of cooling control is expanding in the process of manufacturing thick steel plates by hot rolling.
  • the thick steel plate (not shown) is reheated in the heating furnace 1
  • the thick steel plate is descaled in the descaling device 2.
  • the thick steel plate is rolled by the rolling mill 3 and then corrected by the shape correcting device 4, and then controlled cooling by water cooling or air cooling is performed in the accelerated cooling device 5.
  • the arrow in a figure is the advancing direction of a thick steel plate.
  • the cooling stop temperature when the place where scale thickness is 40 micrometers and 20 micrometers coexists in the thickness direction of a thick steel plate, the cooling stop temperature when cooling a thick steel plate with a thickness of 25 mm from 800 ° C. to a target temperature of 500 ° C. is 40 ⁇ m. It becomes 460 degreeC in a location, and 500 degreeC in a location of 20 micrometers. At the 40 ⁇ m portion, the cooling stop temperature falls below 40 ° C. from the target temperature, and as a result, a uniform material cannot be obtained.
  • Patent Document 1 discloses a method of achieving uniform cooling stop temperature by controlling the scale thickness to equalize the cooling rate.
  • Patent Document 1 using a descaling device provided before and after the rolling mill during rolling, when the cooling stop temperature of the tail end of the thick steel plate is lower than that of the tip, the descaling injection on the tail end side is performed.
  • the amount of water to be greater than the amount of water sprayed on the tip side, and controlling the scale removal rate and remaining thickness in the longitudinal direction of the thick steel plate the heat transfer coefficient of the steel plate surface during controlled cooling can be changed, and the thick steel plate The cooling stop temperature in the longitudinal direction is made uniform.
  • the cooling stop temperature has been made uniform by adjusting the amount of cooling water and the conveyance speed.
  • the cooling rate varies due to the variation in scale thickness, it is difficult not only to make the cooling rate uniform, but also to make the cooling stop temperature uniform.
  • An object of the present invention is to provide a manufacturing method and manufacturing equipment for a thick steel plate that can solve the above-described problems and can secure a high-quality thick steel plate with less material variation.
  • the present invention has been made to solve the above-mentioned conventional problems, and the gist thereof is as follows. [1] In the method for producing a thick steel plate in the order of the hot rolling step, the shape correction step, and the accelerated cooling step, the surface temperature of the thick steel plate is less than the Ar 3 transformation point between the shape correction step and the accelerated cooling step.
  • Temperature adjusting step for transforming the surface of the thick steel plate by cooling it with air or by supplying cooling water to the upper and lower surfaces of the thick steel plate at a water density of 0.3 to 2.2 m 3 / m 2 ⁇ min and cooling with water
  • a method of manufacturing a steel sheet [2] The method for producing a thick steel plate according to [1], wherein, in the descaling step, an injection pressure of the high-pressure water is set to 10 MPa or more.
  • a hot rolling device, a shape correcting device, a temperature adjusting device, a descaling device, and an accelerated cooling device are arranged in this order from the upstream side in the conveying direction, and in the temperature adjusting device, the surface temperature of the thick steel plate is changed to the Ar 3 transformation point.
  • a thick steel plate manufacturing facility is characterized by injecting high-pressure water having an energy density of 0.05 J / mm 2 or more onto the surface of the thick steel plate.
  • an injection pressure of the high-pressure water is set to 10 MPa or more.
  • the temperature adjusting step for transforming the steel plate surface by lowering the steel plate surface temperature below the Ar 3 transformation point, and the steel plate after the temperature adjusting step By having a descaling step of injecting high pressure water having an energy density of 0.05 J / mm 2 or more onto the surface of the film, the cooling rate and the cooling stop temperature can be made uniform. As a result, it is possible to manufacture a high-quality thick steel plate with little material variation.
  • FIG. 1 is a schematic view showing a conventional equipment for producing thick steel plates.
  • FIG. 2 is a diagram showing the relationship among scale thickness, cooling time, and thick steel plate surface temperature during accelerated cooling.
  • FIG. 3 is a diagram showing the relationship between the position in the width direction of the thick steel plate and the cooling stop temperature after accelerated cooling.
  • FIG. 4 is a schematic view showing a thick steel plate manufacturing facility according to an embodiment of the present invention.
  • FIG. 5 is a diagram showing the relationship between the presence or absence of transformation on the surface of the thick steel plate, the energy density of high-pressure water, and the scale peeling rate.
  • FIG. 6 is a diagram showing the relationship between the temperature of the surface of the thick steel plate after the end of rolling and the injection pressure necessary to destroy the scale.
  • FIG. 1 is a schematic view showing a conventional equipment for producing thick steel plates.
  • FIG. 2 is a diagram showing the relationship among scale thickness, cooling time, and thick steel plate surface temperature during accelerated cooling.
  • FIG. 3 is a diagram showing the
  • FIG. 7 is a diagram for defining the temperature difference on the surface of the thick steel plate before the start of the descaling process from the temperature adjustment process.
  • FIG. 8 is a diagram showing the relationship between the temperature drop amount on the surface of the thick steel plate and the variation in the cooling stop temperature.
  • FIG. 9 is a side view of a cooling device according to an embodiment of the present invention.
  • FIG. 10 is a side view of another cooling device according to an embodiment of the present invention.
  • FIG. 11 is a diagram for explaining an example of the nozzle arrangement of the partition wall according to the embodiment of the present invention.
  • FIG. 12 is a diagram for explaining the flow of the cooling drainage on the partition wall.
  • FIG. 13 is a diagram for explaining another flow of the cooling drainage on the partition wall.
  • FIG. 14 is a diagram for explaining a temperature distribution in the width direction of a thick steel plate of a conventional example.
  • FIG. 15 is a diagram illustrating the flow of cooling water in the acceleration cooling device.
  • FIG. 16 is a diagram for explaining non-interference with cooling water on the partition wall in the accelerated cooling device.
  • FIG. 4 is a schematic view showing a thick steel plate manufacturing facility according to an embodiment of the present invention.
  • an arrow is a conveyance direction of a thick steel plate.
  • the heating furnace 1, the descaling device 2, the rolling mill 3, the shape correcting device 4, the temperature adjusting device 6, the descaling device 7, and the accelerated cooling device 5 are arranged in this order.
  • the thick steel plate (not shown) is reheated in the heating furnace 1
  • the thick steel plate is descaled in the descaling device 2 to remove the primary scale.
  • the thick steel plate is hot-rolled by the rolling mill 3 and corrected by the shape correcting device 4.
  • the descaling device 7 completely removes the scale. Scaling is performed.
  • controlled cooling by water cooling or air cooling is performed in the acceleration cooling device 5.
  • a temperature adjustment device 6 and a descaling device 7 are arranged between the shape correction device 4 and the acceleration cooling device 5. Then, the temperature adjustment device 6, to transform the steel plate surface by reducing the steel plate surface temperature Ar less than 3 transformation point. Thereafter, the descaling device 7 performs descaling by injecting high-pressure water having an energy density of 0.05 J / mm 2 or more onto the thick steel plate.
  • the temperature adjustment device 6 is disposed between the shape correction device 4 and the descaling device 7. In temperature control process in a temperature adjustment device 6, by transformation of the steel plate surface by reducing the steel plate surface temperature Ar less than 3 transformation point, in a subsequent descaling step, to facilitate removal of the scale.
  • the steel plate surface is transformed by lowering the surface temperature of the steel plate to below the Ar 3 transformation point, causing transformation of the base iron and causing a shift at the interface between the scale and the base iron. descend. This is considered to be due to the following mechanism.
  • the ground iron transforms from austenite to ferrite.
  • the ground iron expands, a force is applied to the interface between the scale and the ground iron, and a crack is generated at the interface. As a result, it is considered that the adhesion of the scale is reduced.
  • the Ar 3 transformation point can be calculated by the following formula (*).
  • Ar 3 910-310C-80Mn-20Cu-15Cr-55Ni-80Mo (*)
  • an element symbol shows content (mass%) in steel of each element.
  • the descaling device 7 performs descaling for the thick steel plate whose surface is transformed by lowering the surface temperature of the thick steel plate to less than the Ar 3 transformation point.
  • the scale is completely removed by spraying high-pressure water having an energy density of 0.05 J / mm 2 or more (in the present invention, when the spray pressure is 5 MPa or more as high-pressure water) onto the thick steel plate. be able to.
  • high-pressure water having an energy density of 0.05 J / mm 2 or more (in the present invention, when the spray pressure is 5 MPa or more as high-pressure water) onto the thick steel plate.
  • the high pressure water may be sprayed over the entire length of the thick steel plate.
  • the present inventors used a certain steel type, about the influence of the presence or absence of transformation on the surface of the thick steel plate before the descaling process, the energy density of high-pressure water and the scale peeling rate (ratio of the scale peeled area and the thick steel plate area). I investigated the relationship with. As a result, the knowledge shown in FIG. 5 was obtained. From FIG. 5, it was found that when the energy density is large, the scale peeling rate is increased, and by changing the surface of the thick steel plate, the scale peeling is possible even when the energy density is small. Also, from FIG.
  • the energy density of the high pressure water is set to 0.05 J / mm 2 or more.
  • it is 0.10 J / mm 2 or more.
  • the energy density of high-pressure water is preferably 0.60 J / mm 2 or less.
  • the present invention it is preferable to inject high-pressure water having an injection pressure of 10 MPa or more in the descaling step.
  • the injection pressure 10 MPa or more By making the injection pressure 10 MPa or more, the scale can be completely removed. Therefore, the cooling rate and the cooling stop temperature in the accelerated cooling process can be made uniform.
  • the pressure when the high-pressure water droplet collides with the thick steel plate needs to exceed the hardness of the scale.
  • the temperature of the surface of the thick steel plate after the end of rolling is generally around 900 ° C. at the highest. Therefore, in the present invention, in order to destroy the scale, it is preferable to set the injection pressure of the high-pressure water to 10 MPa or more.
  • the energy density E (J / mm 2 ) of the cooling water sprayed onto the thick steel plate is an index of the ability to remove the scale by descaling and is defined as the following equation (1).
  • E Q / (d ⁇ W ) ⁇ ⁇ v 2/2 ⁇ t ...
  • Q Descaling water injection flow rate [m 3 / s]
  • d Flat nozzle spray injection thickness [mm]
  • W Flat nozzle spray injection width [mm]
  • the present inventors adopted water density ⁇ injection pressure ⁇ collision time as a simple definition of the energy density E (J / mm 2 ) of cooling water injected into the thick steel plate. I found out that I should do it.
  • the water density (m 3 / m 2 ⁇ min) is a value calculated by “cooling water injection flow rate ⁇ cooling water collision area”.
  • the injection pressure (MPa) is defined by the discharge pressure of the cooling water.
  • the collision time (s) is a value calculated by “cooling water collision thickness ⁇ thick steel plate conveyance speed”. Note that the relationship between the energy density of the high-pressure water of the present invention and the scale peeling rate calculated by this simple definition is the same as in FIG.
  • the surface temperature of the thick steel plate is lowered below the Ar 3 transformation point by air cooling or water cooling.
  • air cooling on the table rollers for conveying the steel plate may be air cooled as appropriate Ar less than 3 transformation point.
  • cooling water is supplied to the upper and lower surfaces of the thick steel plate at a water density of 0.3 to 2.2 m 3 / m 2 ⁇ min. If the water density is less than 0.3 m 3 / m 2 ⁇ min, the steel plate surface temperature cannot be lowered below the Ar 3 transformation point, and the steel plate surface cannot be transformed. As a result, scale remains on the thick steel plate, and even if cooling control is performed in the subsequent accelerated cooling process, the cooling stop temperature varies and the material becomes non-uniform.
  • the thick steel plate surface is transformed in the temperature adjusting device 6, the thick steel plate surface is cooled in a state where the scale is attached to the thick steel plate.
  • the temperature drop amount by cooling in the temperature adjusting device 6 is large, the present inventors affect the uniformization of the cooling stop temperature and the variation in the cooling stop temperature (the target after the accelerated cooling step). The inventors have found that the difference between the steel sheet surface temperature and the actual steel sheet surface temperature after accelerated cooling is increased.
  • the temperature drop amount ⁇ T on the surface of the thick steel plate in the temperature adjusting device 6 is defined as the difference between the surface temperature of the thick steel plate at the start of cooling and the lowest temperature reached on the surface of the thick steel plate, as shown in FIG.
  • the present inventors manufactured a steel plate in the order of a temperature adjustment step, a descaling step and an accelerated cooling step using a thick steel plate having a surface temperature of 800 ° C. and a plate thickness of 25 mm after the rolling in the rolling mill.
  • the energy density at the time of descaling was set to 0.2 J / mm 2 as a condition that the surface of the steel plate at the time of descaling can be completely removed before and after the transformation.
  • the accelerated cooling process cooling was performed so that the surface temperature of the thick steel plate was 500 ° C.
  • the variation in the cooling stop temperature is 25 ° C. or less and the temperature drop ⁇ T in the temperature adjustment step is 200 ° C. or less.
  • an upper header 11 that supplies cooling water to the upper surface of the thick steel plate 10
  • a cooling water injection nozzle that injects rod-like cooling water suspended from the upper header 11.
  • a partition wall 15 installed between the thick steel plate 10 and the upper header 11, and the partition wall 15 includes a water supply port 16 for inserting a lower end portion of the cooling water injection nozzle 13, and the thick steel plate 10. It is preferable that a large number of drain ports 17 for draining the cooling water supplied to the upper surface onto the partition wall 15 are provided.
  • the upper surface cooling facility includes an upper header 11 for supplying cooling water to the upper surface of the thick steel plate 10, a cooling water injection nozzle 13 suspended from the upper header 11, and the upper header 11 and the thick steel plate 10. And a partition wall 15 having a large number of through-holes (water supply port 16 and drain port 17) installed horizontally in the width direction of the thick steel plate.
  • the cooling water injection nozzle 13 is composed of a circular tube nozzle 13 for injecting rod-shaped cooling water, and its tip is inserted into a through-hole (water supply port 16) provided in the partition wall 15, from the lower end of the partition wall 15. It is installed to be on the top.
  • the cooling water injection nozzle 13 may be inserted into the upper header 11 so that the upper end of the cooling water injection nozzle 13 protrudes into the upper header 11 in order to prevent the foreign matter at the bottom in the upper header 11 from being sucked and clogged. preferable.
  • the rod-shaped cooling water in the present invention is cooling water injected in a state of being pressurized to some extent from a circular (including elliptical or polygonal) nozzle outlet, and is cooled from the nozzle outlet.
  • the water injection speed is 6 m / s or more, preferably 8 m / s or more, and the water flow jetted from the nozzle outlet has a continuous circular shape, and the water flow has a continuous and straight flow.
  • it is different from a free fall flow from a circular tube laminar nozzle or a liquid ejected in a droplet state such as a spray.
  • the reason why the tip of the cooling water spray nozzle 13 is inserted into the through hole and is located above the lower end of the partition wall 15 is that the partition wall 15 is inserted even when a thick steel plate whose tip is warped upward enters. This is to prevent the cooling water injection nozzle 13 from being damaged. As a result, the cooling water injection nozzle 13 can be cooled for a long period of time in a good state, so that it is possible to prevent the occurrence of temperature unevenness in the thick steel plate without repairing the equipment.
  • the tip of the circular tube nozzle 13 since the tip of the circular tube nozzle 13 is inserted into the through-hole, as shown in FIG. 16, it does not interfere with the flow in the width direction of the drained water 19 indicated by the dotted arrow flowing through the upper surface of the partition wall 15. Therefore, the cooling water jetted from the cooling water jet nozzle 13 can reach the upper surface of the thick steel plate equally regardless of the position in the width direction, and uniform cooling in the width direction can be performed.
  • a large number of through-holes having a diameter of 10 mm are opened in a grid pattern at a pitch of 80 mm in the thick steel plate width direction and 80 mm in the transport direction.
  • a cooling water injection nozzle 13 having an outer diameter of 8 mm, an inner diameter of 3 mm, and a length of 140 mm is inserted into the water supply port 16.
  • the cooling water injection nozzles 13 are arranged in a staggered pattern, and the through holes through which the cooling water injection nozzles 13 do not pass serve as cooling water drains 17.
  • the large number of through holes provided in the partition wall 15 of the accelerated cooling device of the present invention are composed of the substantially same number of water supply ports 16 and drain ports 17, and each share a role and function.
  • the total cross-sectional area of the drain port 17 is sufficiently larger than the total cross-sectional area of the inner diameter of the circular pipe nozzle 13 of the cooling water injection nozzle 13, and about 11 times the total cross-sectional area of the inner diameter of the circular pipe nozzle 13 is ensured.
  • the cooling water supplied to the upper surface of the thick steel plate is filled between the thick steel plate surface and the partition wall 15, led to the upper side of the partition wall 15 through the drain port 17, and quickly discharged.
  • the FIG. 12 is a front view for explaining the flow of cooling drainage near the end in the width direction of the thick steel plate on the partition wall.
  • the drainage direction of the drainage port 17 is upward opposite to the cooling water injection direction, and the cooling drainage drained upward from the partition wall 15 changes the direction outward in the thick steel plate width direction, between the upper header 11 and the partition wall 15. It drains through the drainage channel.
  • the drain port 17 is inclined in the thick steel plate width direction, and the slant direction is directed outward in the width direction so that the drain direction is directed outward in the thick steel plate width direction.
  • the cooling water does not easily escape above the partition wall 15 after colliding with the steel plate, and the steel plate 10. And the partition wall 15 flow toward the end in the width direction of the thick steel plate. Then, since the flow rate of the cooling drainage between the thick steel plate 10 and the partition wall 15 increases as it approaches the end in the plate width direction, the force that the jet cooling water 18 penetrates the staying water film and reaches the thick steel plate is the plate width. The direction end portion is inhibited.
  • the plate width is about 2 m at most, the influence is limited. However, the influence cannot be ignored especially in the case of a thick plate having a plate width of 3 m or more. Accordingly, the cooling at the end in the width direction of the thick steel plate is weakened, and the temperature distribution in the width direction of the thick steel plate in this case becomes a non-uniform temperature distribution.
  • the water supply port 16 and the water discharge port 17 are provided separately and share the roles of water supply and water discharge. 15 flows smoothly through the drainage port 17 and above the partition wall 15. Accordingly, since the drainage after cooling is quickly removed from the upper surface of the thick steel plate, the cooling water supplied subsequently can easily penetrate the staying water film, and a sufficient cooling capacity can be obtained.
  • the temperature distribution in the width direction of the thick steel plate is a uniform temperature distribution, and a uniform temperature distribution in the width direction can be obtained.
  • the cooling water is discharged quickly. This can be realized, for example, by making holes larger than the outer diameter of the circular tube nozzle 13 in the partition wall 15 and making the number of drain ports equal to or greater than the number of water supply ports.
  • the ratio of the total cross-sectional area of the drain outlet and the total cross-sectional area of the inner diameter of the circular tube nozzle 13 is preferably in the range of 1.5 to 20.
  • the gap between the outer peripheral surface of the circular tube nozzle 13 inserted in the water supply port 16 of the partition wall 15 and the inner surface of the water supply port 16 be 3 mm or less. If this gap is large, the cooling drainage discharged to the upper surface of the partition wall 15 is drawn into the gap between the outer peripheral surface of the circular pipe nozzle 13 of the water supply port 16 due to the influence of the accompanying flow of the cooling water injected from the circular pipe nozzle 13. As a result, the steel sheet is again supplied onto the thick steel plate, resulting in poor cooling efficiency. In order to prevent this, it is more preferable that the outer diameter of the circular tube nozzle 13 is substantially the same as the size of the water supply port 16. However, in consideration of machining accuracy and mounting errors, a gap of up to 3 mm that has substantially little influence is allowed. More preferably, it is 2 mm or less.
  • the nozzle inner diameter is preferably 3 to 8 mm. If it is smaller than 3 mm, the bundle of water sprayed from the nozzle becomes thin and the momentum becomes weak. On the other hand, when the nozzle diameter exceeds 8 mm, the flow rate becomes slow, and the force penetrating the staying water film becomes weak.
  • the length of the circular tube nozzle 13 is preferably 120 to 240 mm.
  • the length of the circular tube nozzle 13 here means the length from the inlet at the upper end of the nozzle that penetrates into the header to some extent to the lower end of the nozzle inserted into the water supply port of the partition wall.
  • the distance between the lower surface of the header and the upper surface of the partition wall becomes too short (for example, the header thickness is 20 mm, the protrusion amount of the nozzle upper end into the header is 20 mm, and the insertion amount of the nozzle lower end into the partition wall is 10 mm. Therefore, the drainage space above the partition wall becomes small, and the cooling drainage cannot be discharged smoothly.
  • the pressure loss of the circular tube nozzle 13 becomes large, and the force penetrating the staying water film becomes weak.
  • the jet speed of cooling water from the nozzle is required to be 6 m / s or more, preferably 8 m / s or more. This is because if it is less than 6 m / s, the force of the cooling water penetrating through the staying water film becomes extremely weak. If it is 8 m / s or more, a larger cooling capacity can be secured, which is preferable.
  • the distance from the lower end of the cooling water spray nozzle 13 for upper surface cooling to the surface of the thick steel plate 10 is preferably 30 to 120 mm. If it is less than 30 mm, the frequency with which the thick steel plate 10 collides with the partition wall 15 becomes extremely high, and equipment maintenance becomes difficult. If it exceeds 120 mm, the force through which the cooling water penetrates the staying water film becomes extremely weak.
  • draining rolls 20 When cooling the upper surface of the thick steel plate, it is preferable to install draining rolls 20 before and after the upper header 11 so that the cooling water does not spread in the longitudinal direction of the thick steel plate. Thereby, the cooling zone length becomes constant and the temperature control becomes easy.
  • the cooling drainage since the flow of the cooling water in the direction of transporting the thick steel plate is blocked by the draining roll 20, the cooling drainage flows outward in the width direction of the thick steel plate. However, the cooling water tends to stay in the vicinity of the draining roll 20.
  • the cooling water jet nozzles in the uppermost stream side row in the thick steel plate conveyance direction are 15 to 15 upstream in the thick steel plate conveyance direction. It is preferable that the cooling water jet nozzles at the most downstream side in the thick steel plate conveyance direction are inclined 15 to 60 degrees in the downstream direction in the thick steel plate conveyance direction.
  • the distance between the lower surface of the upper header 11 and the upper surface of the partition wall 15 is such that the cross-sectional area in the width direction of the thick steel plate in the space surrounded by the lower surface of the header and the upper surface of the partition wall is 1.5 times the total cross-sectional area of the cooling water spray nozzle inner diameter. For example, it is about 100 mm or more.
  • the cross-sectional area of the thick steel plate in the width direction is not 1.5 times or more than the total cross-sectional area of the cooling water jet nozzle inner diameter, the cooling drainage discharged from the drain port 17 provided on the partition wall to the top surface of the partition wall 15 is smoothly thick. It cannot be discharged in the width direction of the steel sheet.
  • the range of the water density that exhibits the most effect is 1.5 m 3 / m 2 ⁇ min or more.
  • the water density is lower than this, the accumulated water film does not become so thick, and even if a known technique for cooling the thick steel plate by dropping the rod-shaped cooling water freely is applied, the temperature unevenness in the width direction does not become so large. In some cases.
  • the water density is higher than 4.0 m 3 / m 2 ⁇ min, it is effective to use the technique of the present invention, but there are problems in practical use such as an increase in equipment cost.
  • the most practical water density is 1.5 to 4.0 m 3 / m 2 ⁇ min.
  • the application of the cooling technique of the present invention is particularly effective when a draining roll is arranged before and after the cooling header.
  • the header is relatively long in the longitudinal direction (when it is about 2 to 4 m), and it is applied to cooling equipment that sprays water spray for purging before and after the header to prevent water leakage to the non-water cooling zone. Is also possible.
  • the cooling device on the lower surface side of the thick steel plate is not particularly limited.
  • FIGS. 9 and 10 an example of the cooled header 12 including the circular tube nozzle 14 similar to the cooling device on the upper surface side is shown.
  • the injected cooling water naturally falls after colliding with the thick steel plate, so that there is no need for the partition wall 15 for discharging cooling drainage as in the upper surface side cooling in the thick steel plate width direction.
  • heating furnace 1 and the descaling device 2 of the present invention are not particularly limited, and conventional devices can be used.
  • the descaling device 2 need not have the same configuration as the descaling device 7 of the present invention.
  • the steel plate temperature is the temperature of the steel plate surface.
  • the thick steel plate of the present invention was manufactured using a thick steel plate manufacturing facility as shown in FIG. After the slab was reheated in the heating furnace 1, the primary scale was removed in the descaling device 2, hot rolled by the rolling mill 3, and the shape was corrected by the shape correcting device 4. After the shape correction, the temperature adjustment device 6 adjusted the temperature of the surface of the thick steel plate, and then the descaling device 7 performed descaling. In the descaling device 7, the spray distance (the surface distance between the spray nozzle of the descaling device 7 and the thick steel plate) was 130 mm, the nozzle spray angle was 32 °, and the nozzle attack angle was 15 °. After descaling by the descaling device 7, it was cooled to 500 ° C by the acceleration cooling device 5.
  • the temperature adjustment step and the descaling step after temperature adjustment were performed under the conditions shown in Table 1.
  • the cooling length of the temperature adjusting device 6 was 1 m.
  • the Ar 3 transformation point of the thick steel plate used was 780 ° C.
  • the plate thickness after rolling in the rolling mill 3 was 25 mm, and the thick steel plate temperature was 830 ° C.
  • the temperature drop ⁇ T in the temperature adjustment process was measured only when water cooling was employed in the temperature adjustment process. This is because when temperature adjustment is performed by air cooling, problems due to excessive temperature drop do not occur.
  • the temperature adjusting device 6 supplied cooling water to the upper and lower surfaces of the thick steel plate at a water density of 1.0 m 3 / m 2 ⁇ min to lower the surface temperature of the thick steel plate to 750 ° C. Thereafter, in the descaling device 7, high-pressure water was sprayed over the entire length of the thick steel plate at an energy density of 0.08 J / mm 2 , and then cooled by the accelerated cooling device 5. Since the water density for water cooling in the temperature adjusting device 6 was 1.0 m 3 / m 2 ⁇ min, the steel plate temperature during descaling was 750 ° C., and the descaling was performed after the steel plate surface was transformed from austenite to ferrite. Was able to do. Since the temperature drop ⁇ T in the temperature adjustment step was also 120 ° C., the temperature unevenness was 19 ° C.
  • Invention Example 4 the thick steel plate surface temperature was lowered to 770 ° C. in the temperature adjusting device 6 after the end of rolling. Thereafter, in the descaling device 7, high-pressure water was injected over the entire length of the thick steel plate at an energy density of 0.13 J / mm 2 and an injection pressure of 8 MPa, and then cooled by an acceleration cooling device. Since the injection pressure was 8 MPa, which was outside the range preferred in the present invention, it was considered that the scale could not be destroyed and remained slightly, and the temperature unevenness was 23 ° C. Although the injection pressure of Invention Example 4 was larger than that of Invention Example 3 which is within the preferred range of the present invention, the other requirements were satisfied by the present invention, so the target 25 Within ° C was achieved.
  • Comparative Example 1 the surface temperature of the thick steel plate was lowered to 770 ° C. by air cooling in the temperature adjusting device 6 after the end of rolling. Thereafter, in the descaling device 7, high-pressure water was injected over the entire length of the thick steel plate at an energy density of 0.04 J / mm 2 and an injection pressure of 12 MPa, and then cooled by the acceleration cooling device 5. Since the energy density was 0.04 J / mm 2 , it was considered that the scale remained in a part of the thick steel plate, and the temperature unevenness was 36 ° C.
  • the temperature adjusting device 6 does not lower the temperature of the thick steel plate surface, and a thick steel plate having a steel plate surface temperature of 800 ° C. is injected into the descaling device 7 with an energy density of 0.08 J / mm 2 .
  • the high pressure water was sprayed over the entire length of the thick steel plate at a pressure of 15 MPa, it was cooled by the accelerated cooling device 5 and manufactured.
  • the energy density was within the scope of the present invention.
  • the descaling was performed in a state where the surface of the thick steel plate was not transformed, it was considered that the scale remained in a part of the thick steel plate, and the temperature unevenness was 40 ° C.
  • the cooling water was supplied to the upper and lower surfaces of the thick steel plate at a water density of 0.2 m 3 / m 2 ⁇ min in the temperature adjusting device 6 after the end of rolling. Thereafter, in the descaling device 7, high-pressure water was sprayed over the entire length of the thick steel plate at an energy density of 0.08 J / mm 2 , and then cooled by the accelerated cooling device 5. Since the water density was as small as 0.2 m 3 / m 2 ⁇ min, the steel plate temperature was reduced only to 785 ° C., and descaling was performed in a state where the steel plate surface was not transformed.
  • the cooling water was supplied to the upper and lower surfaces of the thick steel plate at a water density of 2.4 m 3 / m 2 ⁇ min in the temperature adjusting device 6 after the end of rolling. Thereafter, in the descaling device 7, high-pressure water was sprayed over the entire length of the thick steel plate at an energy density of 0.08 J / mm 2 , and then cooled by the accelerated cooling device 5. Since the water density was as large as 2.4 m 3 / m 2 ⁇ min, ⁇ T during cooling before descaling was 220 ° C., and temperature unevenness was 27 ° C.

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  • Engineering & Computer Science (AREA)
  • Mechanical Engineering (AREA)
  • Heat Treatments In General, Especially Conveying And Cooling (AREA)
  • Metal Rolling (AREA)
  • Heat Treatment Of Strip Materials And Filament Materials (AREA)
PCT/JP2014/001613 2013-03-27 2014-03-20 厚鋼板の製造方法および製造設備 WO2014156085A1 (ja)

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CN201480018326.5A CN105073293B (zh) 2013-03-27 2014-03-20 厚钢板的制造方法及制造设备
EP14773154.1A EP2979769B1 (en) 2013-03-27 2014-03-20 Thick steel plate manufacturing method and manufacturing device

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JP6518948B2 (ja) * 2016-03-31 2019-05-29 Ｊｆｅスチール株式会社 鋼板の製造方法および製造設備
KR101940872B1 (ko) * 2016-12-21 2019-01-21 주식회사 포스코 유정관용 열연강판, 이를 이용한 강관 및 이들의 제조방법
CN112007963B (zh) * 2019-05-31 2022-08-12 宝山钢铁股份有限公司 带钢表面动态可调整除鳞压力控制方法和系统
JP2023528070A (ja) 2020-06-04 2023-07-03 コンステリウム ヌフ－ブリザック リバース熱間圧延機上での冷却方法および設備
FR3112297B1 (fr) * 2020-07-07 2024-02-09 Constellium Neuf Brisach Procédé et équipement de refroidissement sur un Laminoir réversible à chaud

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WO2010110473A1 (ja) * 2009-03-25 2010-09-30 Ｊｆｅスチール株式会社 厚鋼板の製造設備及び製造方法

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TW201446353A (zh) 2014-12-16
JP2014188543A (ja) 2014-10-06
CN105073293A (zh) 2015-11-18
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TWI569898B (zh) 2017-02-11
JP5720714B2 (ja) 2015-05-20
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