WO2018037916A1 - Procédé de refroidissement de métal à haute température et procédé de production d'un ruban en acier galvanisé par immersion à chaud - Google Patents

Procédé de refroidissement de métal à haute température et procédé de production d'un ruban en acier galvanisé par immersion à chaud Download PDF

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Publication number
WO2018037916A1
WO2018037916A1 PCT/JP2017/028840 JP2017028840W WO2018037916A1 WO 2018037916 A1 WO2018037916 A1 WO 2018037916A1 JP 2017028840 W JP2017028840 W JP 2017028840W WO 2018037916 A1 WO2018037916 A1 WO 2018037916A1
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Prior art keywords
cooling
steel strip
temperature metal
hot
galvanized steel
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PCT/JP2017/028840
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English (en)
Japanese (ja)
Inventor
優 寺崎
高橋　秀行
琢実 小山
亮一 向
章央 山本
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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 MX2019002038A priority Critical patent/MX2019002038A/es
Priority to JP2017557005A priority patent/JP6477919B2/ja
Priority to CN201780050857.6A priority patent/CN109642304B/zh
Publication of WO2018037916A1 publication Critical patent/WO2018037916A1/fr

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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
    • C—CHEMISTRY; METALLURGY
    • C23—COATING METALLIC MATERIAL; COATING MATERIAL WITH METALLIC MATERIAL; CHEMICAL SURFACE TREATMENT; DIFFUSION TREATMENT OF METALLIC MATERIAL; COATING BY VACUUM EVAPORATION, BY SPUTTERING, BY ION IMPLANTATION OR BY CHEMICAL VAPOUR DEPOSITION, IN GENERAL; INHIBITING CORROSION OF METALLIC MATERIAL OR INCRUSTATION IN GENERAL
    • C23C—COATING METALLIC MATERIAL; COATING MATERIAL WITH METALLIC MATERIAL; SURFACE TREATMENT OF METALLIC MATERIAL BY DIFFUSION INTO THE SURFACE, BY CHEMICAL CONVERSION OR SUBSTITUTION; COATING BY VACUUM EVAPORATION, BY SPUTTERING, BY ION IMPLANTATION OR BY CHEMICAL VAPOUR DEPOSITION, IN GENERAL
    • C23C2/00—Hot-dipping or immersion processes for applying the coating material in the molten state without affecting the shape; Apparatus therefor
    • C23C2/04—Hot-dipping or immersion processes for applying the coating material in the molten state without affecting the shape; Apparatus therefor characterised by the coating material
    • C23C2/06—Zinc or cadmium or alloys based thereon
    • C—CHEMISTRY; METALLURGY
    • C23—COATING METALLIC MATERIAL; COATING MATERIAL WITH METALLIC MATERIAL; CHEMICAL SURFACE TREATMENT; DIFFUSION TREATMENT OF METALLIC MATERIAL; COATING BY VACUUM EVAPORATION, BY SPUTTERING, BY ION IMPLANTATION OR BY CHEMICAL VAPOUR DEPOSITION, IN GENERAL; INHIBITING CORROSION OF METALLIC MATERIAL OR INCRUSTATION IN GENERAL
    • C23C—COATING METALLIC MATERIAL; COATING MATERIAL WITH METALLIC MATERIAL; SURFACE TREATMENT OF METALLIC MATERIAL BY DIFFUSION INTO THE SURFACE, BY CHEMICAL CONVERSION OR SUBSTITUTION; COATING BY VACUUM EVAPORATION, BY SPUTTERING, BY ION IMPLANTATION OR BY CHEMICAL VAPOUR DEPOSITION, IN GENERAL
    • C23C2/00—Hot-dipping or immersion processes for applying the coating material in the molten state without affecting the shape; Apparatus therefor
    • C23C2/26—After-treatment
    • C23C2/28—Thermal after-treatment, e.g. treatment in oil bath
    • C—CHEMISTRY; METALLURGY
    • C23—COATING METALLIC MATERIAL; COATING MATERIAL WITH METALLIC MATERIAL; CHEMICAL SURFACE TREATMENT; DIFFUSION TREATMENT OF METALLIC MATERIAL; COATING BY VACUUM EVAPORATION, BY SPUTTERING, BY ION IMPLANTATION OR BY CHEMICAL VAPOUR DEPOSITION, IN GENERAL; INHIBITING CORROSION OF METALLIC MATERIAL OR INCRUSTATION IN GENERAL
    • C23C—COATING METALLIC MATERIAL; COATING MATERIAL WITH METALLIC MATERIAL; SURFACE TREATMENT OF METALLIC MATERIAL BY DIFFUSION INTO THE SURFACE, BY CHEMICAL CONVERSION OR SUBSTITUTION; COATING BY VACUUM EVAPORATION, BY SPUTTERING, BY ION IMPLANTATION OR BY CHEMICAL VAPOUR DEPOSITION, IN GENERAL
    • C23C2/00—Hot-dipping or immersion processes for applying the coating material in the molten state without affecting the shape; Apparatus therefor
    • C23C2/26—After-treatment
    • C23C2/28—Thermal after-treatment, e.g. treatment in oil bath
    • C23C2/29—Cooling or quenching
    • C—CHEMISTRY; METALLURGY
    • C23—COATING METALLIC MATERIAL; COATING MATERIAL WITH METALLIC MATERIAL; CHEMICAL SURFACE TREATMENT; DIFFUSION TREATMENT OF METALLIC MATERIAL; COATING BY VACUUM EVAPORATION, BY SPUTTERING, BY ION IMPLANTATION OR BY CHEMICAL VAPOUR DEPOSITION, IN GENERAL; INHIBITING CORROSION OF METALLIC MATERIAL OR INCRUSTATION IN GENERAL
    • C23C—COATING METALLIC MATERIAL; COATING MATERIAL WITH METALLIC MATERIAL; SURFACE TREATMENT OF METALLIC MATERIAL BY DIFFUSION INTO THE SURFACE, BY CHEMICAL CONVERSION OR SUBSTITUTION; COATING BY VACUUM EVAPORATION, BY SPUTTERING, BY ION IMPLANTATION OR BY CHEMICAL VAPOUR DEPOSITION, IN GENERAL
    • C23C2/00—Hot-dipping or immersion processes for applying the coating material in the molten state without affecting the shape; Apparatus therefor
    • C23C2/34—Hot-dipping or immersion processes for applying the coating material in the molten state without affecting the shape; Apparatus therefor characterised by the shape of the material to be treated
    • C23C2/36—Elongated material
    • C23C2/40—Plates; Strips

Definitions

  • the present invention relates to a method for cooling a high-temperature metal and a method for producing a hot-dip galvanized steel strip.
  • an alloyed hot dip galvanized steel strip is manufactured as follows using a continuous alloying hot dip galvanizing equipment 100 as shown in FIG.
  • the steel strip S annealed in a continuous annealing furnace (not shown) is continuously introduced into the hot dip galvanizing bath 30 where the hot strip galvanizing is applied to the steel strip S.
  • the steel strip S is moved upward by the sink roll 32 in the hot dip galvanizing bath 30.
  • the steel strip S is pulled up above the hot dip galvanizing bath 30 while being guided to the pair of support rolls 34, and then the plating adhesion amount is adjusted by the gas wiping device 36.
  • the zinc plating applied to the steel strip S in the alloying furnace 38 is heated and alloyed.
  • the steel strip S passes through the alloying furnace 38 but is not heated. Then, the droplet group which refined the cooling liquid with the mist cooling device 10 is sprayed toward the steel strip S, and the steel strip S is cooled.
  • cooling As a cooling method after such hot-dip galvanizing or alloying, cooling (gas cooling) in which a gas such as air is injected, and cooling in which a droplet group in which the coolant is miniaturized as shown in FIG. 1 are injected. (Mist cooling). Mist cooling has higher cooling efficiency than gas cooling, and can be suitably used because cooling can be performed at a high cooling rate with a limited cooling facility length and productivity can be improved.
  • FIG. 6 shows the relationship between the surface temperature of the high-temperature metal and the cooling capacity (heat transfer coefficient).
  • the cooling capacity is low at the stage where the surface temperature is high (film boiling region in FIG. 6).
  • FIG. 7 many vapor films M are generated between the surface of the steel strip S and the cooling liquid L, and this vapor film M makes direct contact between the surface of the steel strip S and the cooling liquid L. Because it hinders.
  • the hot dip galvanized steel sheet has a plate width exceeding 1000 mm, and the maximum plate width may approach 1900 mm, but quality uniformity in the width direction is required.
  • the cooling liquid is increased in order to increase the cooling capacity, the cooling is performed in the transition boiling region shown in FIG.
  • Patent Document 1 As a technique aimed at improving the cooling capacity in the film boiling region.
  • electrodes are arranged on the front and back or the periphery of the high-temperature metal via the cooling water, and a voltage of 100 is applied to the vapor film generation region using the high-temperature metal as an electrode.
  • a cooling method for high-temperature metal is described in which an electric field of ⁇ 2000 V is applied and the vapor film generated on the high-temperature metal surface is destroyed by this electric field, and cooling is performed. The example applied to is described.
  • Patent Document 2 discloses that in a cooling process of metal heat treatment, a liquid-gas mixed liquid in which gas microbubbles are dispersed in a liquid is used as a cooling medium, and the microbubbles are kept in a uniformly dispersed state by maintaining a uniform dispersion state.
  • a cooling method for metal heat treatment is described, characterized in that it prevents uniform vapor film formation and enables uniform and stable cooling.
  • Patent Document 2 states that the cooling capacity can be controlled by controlling the liquid amount, the liquid temperature, and the gas content (void ratio), and it is described that this cooling method is applied to carburizing and quenching of steel. As an example, dipping cooling (carburization quenching) is described as an example.
  • JP-A-5-69029 Japanese Patent Laid-Open No. 60-55614
  • Patent Document 2 a liquid-gas mixed liquid in which micro bubbles having an air bubble diameter of 0.1 to 1 mm are dispersed is used.
  • Patent Document 2 describes that this cooling method prevents uniform formation of a vapor film of a material to be cooled and enables uniform and stable cooling.
  • Patent Document 2 does not discuss what mechanism prevents vapor film formation.
  • a cooling liquid in which fine bubbles of 0.1 to 1 mm are dispersed cannot obtain a sufficient cooling ability, and is likely to cause uneven cooling.
  • the present invention provides a method for cooling a high-temperature metal with a jet liquid that can sufficiently improve cooling capacity and can perform uniform cooling without using an apparatus having a complicated configuration, and the method. It aims at providing the manufacturing method of the hot-dip galvanized steel strip used.
  • the present inventors studied to contain microbubbles having a bubble diameter of a predetermined value or less in the coolant. This is based on the idea that the pressure generated by the microbubbles adhering to the metal surface and crushing destroys the vapor film produced by the film boiling of the coolant, resulting in improved cooling capacity. Based.
  • the crushing phenomenon is a phenomenon in which a very small bubble shrinks with the pressure in the liquid, and the pressure inside the bubble rises rapidly, and when it exceeds the limit, it becomes a high pressure state and generates a big impact. This phenomenon does not occur and is unique to microbubbles (see Bull. Soc. Sea Water Sci., Jpn., 64, 4-10 (2010)). According to the study by the present inventors, this crushing phenomenon hardly occurs in the cooling liquid in which relatively coarse bubbles such as 0.1 mm or more described in Patent Document 2 are dispersed.
  • liquids containing microbubbles have been used in fields such as long-term storage of food and improvement of water purification, they have not been used for cooling high-temperature metals being transported.
  • the inventors of the present invention cooled a hot metal being transported in a film boiling region using a coolant containing microbubbles having a bubble diameter of a predetermined value or less, and used a conventional coolant that does not contain microbubbles. It was found that the cooling capacity was drastically improved compared to the case where it was. This is thought to be because the vapor film was destroyed by the crushing phenomenon of microbubbles.
  • a cooling capacity that cannot be achieved without increasing the amount of cooling liquid and accepting cooling unevenness with a normal mist can be achieved with a small amount of cooling liquid in the present invention. Therefore, not only an improvement in cooling capacity but also a uniform cooling is possible.
  • the gist configuration of the present invention completed based on the above findings is as follows.
  • (1) A method for cooling a high-temperature metal comprising supplying a coolant containing microbubbles toward the high-temperature metal being transported and cooling the high-temperature metal with the coolant.
  • the hot dip galvanized steel strip contains Al: 1.0 to 10% by mass, Mg: 0.2 to 1.0% by mass, and Ni: 0.005 to 0.1% by mass, and the balance is composed of Zn and inevitable impurities.
  • the hot dip galvanized steel strip contains Al: 25 to 75% by mass and Si: 0.5 to 10% by mass, and the remainder has a plating layer having a composition composed of Zn and inevitable impurities (9 The method for cooling a high-temperature metal as described in 1).
  • a sufficient improvement in cooling capacity and uniform cooling can be realized without using a complicated apparatus in the method for cooling a high-temperature metal with a jet liquid.
  • a hot dip galvanized steel strip of the present invention a hot dip galvanized steel strip having a beautiful surface appearance can be produced.
  • FIG. 1 It is a schematic diagram of the continuous alloying hot dip galvanizing equipment 100 used in one embodiment of the present invention.
  • (A) is the partial schematic diagram of the mist cooling device 10 described in FIG. 1
  • (B) is the figure which extracted 1 set of headers of (A).
  • It is a schematic diagram of the mist cooling device 10 described in FIG. It is a schematic diagram which shows an example of the manufacturing system of the cooling water containing microbubbles used by one Embodiment of this invention. It is a schematic diagram which shows the other example of the manufacturing system of the cooling water containing microbubbles used by one Embodiment of this invention.
  • the method for cooling a high-temperature metal according to the present invention is characterized in that a cooling liquid containing microbubbles is supplied toward the high-temperature metal being conveyed, and the high-temperature metal is cooled by the cooling liquid.
  • a cooling liquid containing microbubbles is supplied toward the high-temperature metal being conveyed, and the high-temperature metal is cooled by the cooling liquid.
  • a continuous alloying hot dip galvanizing equipment 100 used in a method of manufacturing a hot dip galvanized steel strip according to an embodiment of the present invention is described with reference to FIG. 1.
  • An annealing furnace (not shown), a hot dip galvanizing bath 30, a sink roll 32, a support roll 34, a gas wiping device 36, an alloying furnace 38, a mist cooling device 10, a scanning radiation thermometer 40, and a top roll 42.
  • the steel strip S annealed in a continuous annealing furnace (not shown) is continuously introduced into the hot dip galvanizing bath 30, where the hot strip galvanizing is applied to the steel strip S.
  • the steel strip S is moved upward by the sink roll 32 in the hot dip galvanizing bath 30.
  • the steel strip S is pulled up above the hot dip galvanizing bath 30 while being guided to the pair of support rolls 34, and then the plating adhesion amount is adjusted by the gas wiping device 36. Thereafter, in the case where the steel strip S is a steel type to be alloyed, the zinc plating applied to the steel strip S in the alloying furnace 38 is heated and alloyed.
  • the steel strip S When the steel strip S is a steel type that is not alloyed, the steel strip S passes through the alloying furnace 38 but is not heated. Then, the droplet group which refined the cooling liquid with the mist cooling device 10 is sprayed toward the steel strip S, and the steel strip S is cooled. Thereafter, the steel strip temperature is measured by the radiation thermometer 40 in the vicinity of the top roll 42.
  • the configuration of the cooling device 10 will be described with reference to FIGS. 2 (A), (B), and FIG.
  • the main parts of the cooling device 10 are a nozzle header 12 and a nozzle 14 attached thereto.
  • the nozzle header includes an air header that is illustrated and a water header that is disposed inside the nozzle header and is not illustrated.
  • Each of the air header and the water header is supplied with air pressurized to a predetermined pressure and water as a coolant. Air and water are mixed inside the nozzle 14, and as a result, the water is refined and droplets are sprayed toward the steel strip S from the opening of the nozzle 14.
  • one nozzle header 12 is provided with a plurality of nozzles 14 at predetermined intervals in the longitudinal direction.
  • the nozzle header 12 Since the nozzle header 12 is installed such that its longitudinal direction coincides with the width direction of the steel strip S, the steel strip S can be cooled in the width direction. As shown in FIG. 2A, a plurality of nozzle headers 12 are arranged in the traveling direction of the steel strip S according to the cooling equipment length. Furthermore, since the nozzle header 12 is arrange
  • the coolant is not particularly limited, but is preferably water-based and most preferably pure water.
  • the nozzle pitch in the width direction can be appropriately determined so that the spread angle of the nozzle 14 alone is investigated and a uniform amount of water can be sprayed onto the steel strip S in the width direction.
  • the mist injected from the nozzle 14 collides with the steel strip S and evaporates or rebounds and is collected from the exhaust duct 16.
  • the droplets that have condensed on contact with the inner wall of the cooling box or the nozzle header 12 flow downward and are collected by the water pan 18.
  • a sealing device for preventing water leakage to the lower part is provided at the lowermost part of the cooling box. Examples of the sealing device include a static pressure pad 20 that forms a pressure pool on the surface of the steel strip and a gas nozzle 22 that forms an upward flow near the steel strip.
  • the sealing device is not limited to this form.
  • the structure of the cooling device 10 is not limited to that described above as long as it is a device capable of spraying a droplet group.
  • a coolant containing microbubbles is supplied to the nozzle header 12, and this coolant is sprayed as a mist, and the steel strip S is cooled by this mist.
  • the temperature of the steel strip S provided to the cooling device 10 depends on the components of the hot-dip zinc and the alloying temperature. Generally, the temperature is 340 to 550 ° C.
  • the temperature of the steel strip S when passing through the top roll 42 is preferably 300 ° C. or less, and more preferably about 150 to 250 ° C. If the temperature exceeds 300 ° C., the molten zinc adheres to the top roll 42, so that the surface of the steel strip S is wrinkled and the surface appearance of the steel strip S may be inferior.
  • the cooling in such a temperature range includes the cooling in the film boiling region shown in FIG.
  • the cooling in this region is preferable from the viewpoint of suppressing uneven cooling of the steel strip S because the change in the cooling capacity with respect to the temperature change is small and a stable heat flow rate is obtained.
  • the low point is the difficulty.
  • the cooling liquid containing microbubbles is sprayed as mist, and the steel strip S is cooled by this mist, so compared to the case of using a conventional cooling liquid that does not contain microbubbles. , The cooling capacity is dramatically improved. This is presumably because the vapor film was destroyed by the above-described microbubble collapse phenomenon.
  • the cooling capacity which cannot be achieved without increasing the amount of cooling liquid and accepting uneven cooling with normal mist can be achieved with a small amount of cooling liquid. Therefore, since cooling in the transition boiling region can be avoided, not only improvement in cooling capacity but also uniform cooling is possible.
  • the steel strip S is cooled by mist.
  • mist in this specification means a droplet group having an average droplet diameter of 200 ⁇ m or less on the Sauter average.
  • the lower limit of the average droplet diameter of the mist is not particularly limited, but from the viewpoint of stably containing the microbubbles in the mist, the average Sauter average is preferably 70 ⁇ m.
  • the diameter of the mist can be measured by irradiating the droplet with laser light. The diameter of the mist can be appropriately adjusted by controlling the diameter of the spray port of the nozzle 14 and the flow rate of the liquid (water) in the nozzle header 12.
  • microbubble means a bubble having a diameter of 50 ⁇ m or less, and includes a bubble also called a nanobubble having a diameter of nanometer order.
  • the above-mentioned crushing phenomenon hardly occurs, but in the cooling liquid containing microbubbles, the above-mentioned crushing phenomenon occurs, so that the cooling is drastically reduced.
  • Ability improves.
  • the average diameter of the microbubbles is preferably 20 ⁇ m or less, more preferably 10 ⁇ m or less, and 1 ⁇ m or less. More preferably, it is most preferably 0.2 ⁇ m or less.
  • the average diameter is preferably 0.01 ⁇ m or more.
  • the relationship between the bubble particle size and the heat transfer coefficient is shown in FIG.
  • the experiment was performed as follows. A thermocouple was attached to the center of a SUS304 (plate thickness 1.0 mm ⁇ length 200 mm ⁇ width 200 mm) cut plate, submerged in a water tank containing 2 L of microbubble water, and cooled by immersion. Temperature of the cooling water is 20 ° C., bubbles mixed amount of cooling water was 10 9 / L. The diameter of the bubble in the mist is 0.01 ⁇ m, 0.1 ⁇ m, 0.2 ⁇ m, 0.5 ⁇ m, 1 ⁇ m, 2 ⁇ m, 5 ⁇ m, 10 ⁇ m, 20 ⁇ m, 30 ⁇ m, 40 ⁇ m, and 50 ⁇ m. Until cooled.
  • the heat transfer coefficient is calculated from the temperature of the attached thermocouple, and is an average value of the steel sheet temperature of 100 to 200 ° C.
  • a broken line is a heat transfer coefficient at the time of cooling with the pure water which does not contain microbubble water.
  • the heat transfer coefficient increases only about 10% compared to pure cooling, whereas at 20 ⁇ m, the heat transfer coefficient increases by 20% or more.
  • the heat transfer coefficient increases by 80% and shows an almost constant value.
  • the smaller the microbubble particle size the slower the microbubble flying speed, so 0.2 ⁇ m or less is more desirable.
  • the average diameter of the microbubbles in the cooling water supplied to the nozzle header 12 is preferably 20 ⁇ m or less, and preferably 10 ⁇ m or less. More preferably, it is more preferably 1 ⁇ m or less, and most preferably 0.2 ⁇ m or less.
  • average diameter of bubbles is defined as the Sauter average value of the distribution obtained by sampling 10 mL of the cooling liquid, measuring with a particle size distribution measuring device, and averaging the obtained particle size distribution.
  • a laser diffraction / scattered light method is used in which diffraction / scattered light generated when laser light is irradiated to the bubble is measured and a particle diameter is calculated from the scattered light pattern.
  • the mixing amount of bubbles in the coolant is not particularly limited, but from the viewpoint of sufficiently obtaining the effect of improving the cooling capacity, 1 ⁇ 10 8 / L
  • the number is 1 ⁇ 10 9 pieces / L or more, more preferably 1 ⁇ 10 11 pieces / L or more.
  • the upper limit of the amount of bubbles mixed is not particularly limited, but can be 1 ⁇ 10 14 / L or less from the viewpoint of ease of bubble generation.
  • the “bubble mixing amount” can be measured from the number of particles (number of bubbles) using a particle size distribution measuring apparatus after collecting 10 mL of the cooling liquid in the same manner as the average diameter of the bubbles.
  • the gas in the microbubble is not particularly limited, but a gas having a low solubility in water, such as nitrogen, air, or oxygen, is desirable. This is because the smaller the solubility, the higher the internal pressure of the bubbles, and the more the vapor film is removed, and the cooling capacity is expected to be improved.
  • the amount of the coolant supplied to the steel strip is not particularly limited, but is preferably 0.05 to 0.8 L / min.
  • the amount of the coolant supplied to the steel strip is not particularly limited, but is preferably 0.05 to 0.8 L / min.
  • the method for producing the microbubble-containing liquid is not particularly limited, and a known or arbitrary microbubble generation method can be used.
  • a known or arbitrary microbubble generation method can be used.
  • swirling liquid flow type static mixer type, ejector type, venturi type, pressure dissolution type, pore
  • a bubble generating device such as a formula, a rotary type, an ultrasonic type, a vapor condensation type, and an electrolysis type can be used.
  • FIG. 4 an example of a production system of cooling water containing microbubbles, which can be applied to the present embodiment, will be described.
  • Fresh water and gas are caused to flow into the bubble generating device 50 through two lines of piping connected to the bubble generating device 50.
  • Microbubble-containing cooling water is generated by the bubble generation device 50 and stored in the storage tank 60 via a pipe.
  • the cooling water in the storage tank 60 is distributed and supplied to each nozzle header 12 by a pump 62.
  • the amount of fresh water and gas flowing into the bubble generating device 50 may be determined as appropriate so as to be the amount of bubbles mixed in the cooling water, and adjusted by the valves 52 and 56 and the pump 54. Or based on the measured value of the radiation thermometer 40, the control apparatus 58 may calculate suitable inflow, and may adjust with the valves 52 and 56, respectively.
  • the microbubble-containing cooling water can be manufactured with an apparatus having such a simple configuration.
  • the types of the pump 54 for transferring the cooling water before containing microbubbles and the pump 62 for transferring the cooling water containing microbubbles are not particularly limited, and any positive displacement pump or non-positive displacement pump can be used.
  • Examples of positive displacement pumps include reciprocating pumps such as plunger pumps, diaphragm pumps, and piston pumps, and rotary pumps such as gear pumps, eccentric pumps, and screw pumps.
  • Examples of non-displacement pumps include centrifugal pumps, mixed flow pumps, and axial flow pumps.
  • the pump 62 for transferring the cooling water containing microbubbles is preferably a positive displacement pump.
  • the positive displacement pump is a pump that transfers the liquid by changing the volume of the liquid in a constant volume space by the reciprocating motion of a mechanical element (diaphragm in the case of a diaphragm pump). According to this method, since the cooling water is not stirred, the cooling water can be transferred at a predetermined pressure while preventing the defoaming of the microbubbles in the cooling water. Therefore, higher cooling capacity can be exhibited.
  • the diaphragm pump is particularly preferable because it is the structure in which the coolant is most difficult to stir.
  • a non-positive displacement pump is a pump that rotates an impeller in a casing and transfers liquid.
  • the non-displacement pump since the impeller agitates the liquid, the microbubbles in the cooling water gather and coalesce, and the microbubbles having a large bubble diameter are easily defoamed. Therefore, it is desirable to use a positive displacement pump when transferring cooling water containing microbubbles.
  • the microbubble-containing cooling water generated by the bubble generating device 50 is distributed and supplied to the nozzle headers 12 as they are through the piping without using a pump.
  • Such an embodiment is applicable when a self-priming mist nozzle is used, or when the cooling water before containing microbubbles has already been pressurized to a pressure higher than a predetermined level such as 0.1 to 0.5 MPa. is there.
  • a predetermined level such as 0.1 to 0.5 MPa.
  • the cooling of the alloyed hot metal plated steel strip obtained by heating alloying the galvanizing applied to the steel strip S prior to cooling has been described.
  • the present invention is not limited to this, and alloying is performed.
  • the cooling method of the present invention can be applied to the cooling of the hot-dip galvanized steel strip that is not performed.
  • composition of the plated layer of the hot dip galvanized steel strip is not particularly limited, and includes, for example, Al: 1.0 to 10% by mass, Mg: 0.2 to 1.0% by mass, and Ni: 0.005 to 0.1% by mass,
  • the balance may be composed of Zn and unavoidable impurities, Al: 25 to 75% by mass, Si: 0.5 to 10% by mass, and the balance composed of Zn and unavoidable impurities. It can also have.
  • the method for cooling a high-temperature metal of the present invention can be applied not only to mist cooling of a hot-dip galvanized steel strip, but also to any cooling in a system in which a coolant is supplied to a high-temperature metal being conveyed.
  • cooling by droplets not limited to mist includes secondary cooling of a continuous casting machine and coil yard cooling of a hot rolled coil.
  • cooling liquid is jetted as a liquid flow, the liquid flow is collided with the high temperature metal, and the high temperature metal is cooled by the liquid flow. Cooling on a run-out table.
  • the temperature at the start of cooling of the metal body to be cooled is not particularly limited as long as the cooling of the metal body becomes a film boiling region.
  • the temperature that becomes the film boiling region depends on the surface state (for example, roughness) of the metal body to be cooled and the cooling mode (cooling liquid supply method, for example, mist cooling, spray cooling, cooling by immersion).
  • Example 1 Using the continuous alloying hot dip galvanizing equipment shown in FIGS. 1 to 4, hot dip galvanized steel strips were produced under various conditions.
  • a steel strip was obtained.
  • the temperature of the plating bath was adjusted to an appropriate value according to the plating composition and is shown in Table 1.
  • hot galvanizing was not performed by heating.
  • One exhaust fan was installed at the connecting part of the damper, and the air flow was operated at a constant output of 3600 m 3 / hr.
  • cooling water containing microbubbles nitrogen
  • flat spray type nozzles were provided at 9 locations at intervals of 200 mm in the steel strip width direction
  • nozzle headers were provided in 40 stages in the traveling direction of the steel strip.
  • the nozzle rows adjacent to each other in the traveling direction of the steel strip were arranged so that the positions in the width direction of the nozzles were shifted by 50 mm.
  • the distance between the nozzle and the steel strip was 200 mm.
  • Table 1 shows the average diameter of bubbles in the cooling water, the amount of bubbles mixed in the cooling water, and the amount of cooling water.
  • the cooling water sample for measuring an average diameter and a bubble mixing amount was extract
  • the cooling water was sprayed as mist, and the steel strip was cooled by this mist.
  • the average droplet diameter of the mist was 100 ⁇ m.
  • the temperature of the steel strip was measured with a radiation thermometer installed at the outlet side position of the cooling device.
  • the measurement temperature is shown in “Top roll passage plate temperature” in Table 1.
  • the surface external appearance of the hot dip galvanized steel strip manufactured in each Example was evaluated, and the results are shown in Table 1.
  • the invention example using microbubble-containing cooling water is a comparative example using ordinary cooling water not containing microbubbles.
  • the top roll passage plate temperature could be lowered.
  • the top roll passage plate temperature was high in the comparative example, scuffs were generated on the surface of the steel strip.
  • Comparative Examples No. 17 and 21 since the plating layer was soft, large scratches were generated.
  • Comparative Example No. 5 the amount of cooling water was increased compared to No. 1 to 4 in order to obtain the same top roll passing plate temperature as that of the No. 1 invention example. A belt meander has occurred.
  • Example 2 A hot dip galvanized steel strip was produced as Invention Examples No. 22 and 23 under the same conditions and method as Invention Example No. 1 except that the method of transferring the microbubble-containing cooling water to the nozzle header was changed.
  • the plating layer composition and bath temperature were Invention Example No. 1, Al: 0.2 mass%, Zn: the balance of the composition, and 460 ° C.
  • Example No. 22 using the microbubble-containing cooling water manufacturing system shown in FIG. 5, the microbubble-containing cooling water liquid was transferred without using a pump and supplied to the nozzle header. At this time, the pressure of the cooling water before containing microbubbles was increased from 0.05 MPa of No. 1 to 0.3 MPa.
  • a centrifugal pump 200 SZM, manufactured by Ebara Corporation was used as a pump for transferring the cooling water containing microbubbles from the storage tank to the nozzle header.
  • the average diameter of the bubbles and the amount of bubbles mixed in the cooling water were measured before and after passing through the pump. Cooling water before passing through the pump was collected from the bubble generator. The cooling water after passing through the pump was collected from a sampling hole provided in the pipe to the nozzle header. Moreover, it carried out similarly to Example 1, and investigated the top roll passage plate temperature, the surface appearance of a steel strip, and the presence or absence of meandering. The results are shown in Table 2.
  • Invention Example No. 22 which does not use a pump, can achieve a sufficiently low top roll passage plate temperature as in Invention Example No. 1 which uses a positive displacement pump. A hot-dip galvanized steel strip was obtained. In these cases, there was no change in the average diameter of the bubbles before and after passing through the pump. In contrast, in Invention Example No. 23 using a non-positive displacement pump, the top roll passage plate temperature was higher than in Invention Examples No. 1 and 22. Moreover, the bubble diameter after passing through the pump has become larger than before passing through the pump.
  • a sufficient improvement in cooling capacity and uniform cooling can be realized without using a complicated apparatus in the method for cooling a high-temperature metal with a jet liquid.
  • a hot dip galvanized steel strip of the present invention a hot dip galvanized steel strip having a beautiful surface appearance can be produced.

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  • Chemical & Material Sciences (AREA)
  • Engineering & Computer Science (AREA)
  • Mechanical Engineering (AREA)
  • Chemical Kinetics & Catalysis (AREA)
  • Materials Engineering (AREA)
  • Metallurgy (AREA)
  • Organic Chemistry (AREA)
  • Physics & Mathematics (AREA)
  • Oil, Petroleum & Natural Gas (AREA)
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  • Coating With Molten Metal (AREA)

Abstract

La présente invention décrit un procédé de refroidissement de métal à haute température qui, sans utiliser de dispositif présentant une configuration compliquée, améliore la performance de refroidissement et permet le refroidissement uniforme à l'aide d'un liquide d'injection. Le procédé de refroidissement de métal à haute température selon la présente invention est caractérisé en ce qu'il consiste en le refroidissement d'un métal à haute température qui est transporté, avec un liquide de refroidissement contenant des microbulles en alimentant le liquide de refroidissement au métal à haute température.
PCT/JP2017/028840 2016-08-22 2017-08-08 Procédé de refroidissement de métal à haute température et procédé de production d'un ruban en acier galvanisé par immersion à chaud WO2018037916A1 (fr)

Priority Applications (3)

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MX2019002038A MX2019002038A (es) 2016-08-22 2017-08-08 Metodo de enfriamiento de metal a alta temperatura y metodo de produccion de bandas de acero galvanizado por inmersion en caliente.
JP2017557005A JP6477919B2 (ja) 2016-08-22 2017-08-08 高温金属の冷却方法及び溶融亜鉛めっき鋼帯の製造方法
CN201780050857.6A CN109642304B (zh) 2016-08-22 2017-08-08 高温金属的冷却方法及熔融镀锌钢带的制造方法

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JP2020105612A (ja) * 2018-12-28 2020-07-09 日本製鉄株式会社 冷却方法及び冷却装置
CN112593177A (zh) * 2020-10-23 2021-04-02 宝钢集团南通线材制品有限公司 钢丝热浸镀锌基多元合金后的镀层冷却方法及冷却装置
JP7444149B2 (ja) 2020-12-01 2024-03-06 Ｊｆｅスチール株式会社 コイル状熱延鋼板の冷却方法およびその冷却装置

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CN113210147B (zh) * 2021-05-21 2022-11-08 重庆赛迪热工环保工程技术有限公司 喷嘴结构及具有该喷嘴结构的锌铝镁专用分段式冷却器

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JPH09125271A (ja) * 1995-09-01 1997-05-13 Keramchem Gmbh 冷間圧延されたストリップを一の作業工程で造るための方法
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JPS5458664A (en) * 1977-10-19 1979-05-11 Hitachi Ltd Cold rolling method
JPS54110934A (en) * 1978-02-20 1979-08-30 Daido Steel Co Ltd Method and apparatus for jet type cooling of strip in continuous plating machine
JPH0681107A (ja) * 1992-09-02 1994-03-22 Totoku Electric Co Ltd 溶融めっき線の冷却装置
JPH09125271A (ja) * 1995-09-01 1997-05-13 Keramchem Gmbh 冷間圧延されたストリップを一の作業工程で造るための方法
JP2011001631A (ja) * 2009-05-20 2011-01-06 Nippon Steel Corp 表面性状に優れた合金化溶融亜鉛めっき鋼板の製造方法

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JP2020105612A (ja) * 2018-12-28 2020-07-09 日本製鉄株式会社 冷却方法及び冷却装置
JP7265117B2 (ja) 2018-12-28 2023-04-26 日本製鉄株式会社 冷却方法及び冷却装置
CN112593177A (zh) * 2020-10-23 2021-04-02 宝钢集团南通线材制品有限公司 钢丝热浸镀锌基多元合金后的镀层冷却方法及冷却装置
JP7444149B2 (ja) 2020-12-01 2024-03-06 Ｊｆｅスチール株式会社 コイル状熱延鋼板の冷却方法およびその冷却装置

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MX2019002038A (es) 2019-07-01

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