JP2006316345A - Process for cooling steel strip in cooling zone of continuous heat treatment equipment and cooling apparatus - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a method and apparatus for cooling a steel strip with which in a cooling zone of a continuous heat-treatment equipment, the cooling rate having good cooling efficiency is secured and the generation of oxide film is restrained. <P>SOLUTION: The method for cooling the steel strip in the cooling zone of the continuous heat-treatment equipment, is performed as the followings, with which the steel strip is cooled with water or gas and water through a water-cooling device or a gas and water cooling device 18 by using deaerated-water reduced to dissolved oxygen quantity in the cooling water with a deaerator 24 in the cooling zone 4 of the continuous heat-treatment equipment for heat-treating by continuously passing the steel strip 1. Hydrogen-containing gas can be blown through a hydrogen-containing gas-blown cooling device 25 to the water-cooled or gas-water-cooled steel strip, at the downstream side of the water cooling device or the gas-water cooling device 18. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a steel strip cooling method and a cooling apparatus for cooling a steel strip with water or air-water using cooling water in which dissolved oxygen is reduced in a cooling zone of a continuous heat treatment facility.

  The steel strip is processed by hot and / or cold annealing. Patent Document 1 discloses a steel strip switching type continuous heat treatment facility. FIG. 2 is a schematic view showing an example of a steel strip switching continuous heat treatment facility.

  In FIG. 2, when the hot dip galvanized steel strip is manufactured, the steel strip 1 is passed through the heating zone 2, the soaking zone 3, and the cooling zone 4 in this order, and then introduced into the hot dip galvanizing pot 6 via the snout 5. After being adjusted to a predetermined plating thickness by the plating adhesion amount adjuster 7 and, if necessary, alloyed by the alloying device 8, it is cooled to a predetermined temperature or lower by the cooling device 9, and the top roll 10, after being cooled by the air jet cooler type cooling device 11, it is finally cooled in the final cooling zone 12.

  Moreover, when not hot-dip galvanized, it is switched to the annealing line by the line switching device 13, and the steel strip 1 is overheated zone 2, soaking zone 3, cooling zone 4 and overaging zones 14 and 15 for performing overaging treatment, and finally The cooling plates 12 are passed through in order.

  The steel strip annealed by the continuous heat treatment equipment is subjected to chemical conversion treatment or plating on the surface. In this case, if an oxide film is formed on the surface, chemical conversion treatment and plating are not sufficiently performed, and subsequent adhesion and corrosion resistance are impaired. Therefore, in the steel strip to which chemical conversion treatment or plating is performed, it is necessary to cool the annealed steel strip without oxidation. When the steel strip is cooled without oxidation, it is performed with a non-oxidizing gas such as nitrogen. This is because the steel strip is oxidized when an oxidizing gas such as oxygen is contained in the gas.

When the steel strip is cooled with water, oxidation of the steel strip cannot be avoided because water itself is oxidizing. Therefore, when the thickness of the steel strip is thick or a relatively fast cooling rate is required, the required cooling rate cannot be obtained by cooling with gas, and cooling with water is required. In this case, in order to remove the oxide film formed on the steel strip surface, post-treatment such as pickling is required after annealing.
JP 2002-155318 A

  When the steel strip is cooled without oxidation, cooling using a non-oxidizing gas such as nitrogen is performed, and gas jet cooling is also performed in the cooling zone of the continuous annealing equipment. However, in the cooling using gas, when the steel strip is thick or a relatively fast cooling rate is required, there remains a problem that a necessary cooling rate cannot be obtained.

  The present invention provides a cooling method and a cooling device for a steel strip that secures a cooling rate with good cooling efficiency and suppresses the formation of an oxide film in the cooling zone of a continuous heat treatment facility.

  The cooling method of the steel strip in the cooling zone of the continuous heat treatment equipment of the present invention is the cooling of the continuous heat treatment equipment when the steel strip is continuously passed through and cooled in the cooling zone of the continuous heat treatment equipment and subsequently subjected to hot dip galvanizing treatment. In the method for cooling a steel strip in a strip, the steel strip is water-cooled or air-water cooled using deaerated water in which the amount of dissolved oxygen in the cooling water is reduced by a deaeration device.

  In the above-described configuration, the oxide film may be reduced by hydrogen reduction by spraying a hydrogen-containing gas on a steel strip cooled with water or air.

  Further, the present invention provides a method for cooling a steel strip in a cooling zone of a continuous heat treatment facility that continuously heats the steel strip and heat-treats deaerated water in which the amount of dissolved oxygen in the cooling water is reduced by a deaerator. The steel strip is used for water cooling or air-water cooling, and a hydrogen-containing gas is sprayed onto the water-cooled or air-water cooled steel strip to reduce the oxide film by hydrogen reduction.

  Further, the cooling device in the cooling zone of the continuous heat treatment facility of the present invention is a cooling zone of the continuous heat treatment facility when the steel strip is continuously passed through and cooled in the cooling zone of the continuous heat treatment facility and subsequently hot dip galvanized. Further, the present invention is characterized in that a water cooling device for cooling the steel strip with water or an air-water cooling device for cooling with water is provided using deaerated water in which the amount of dissolved oxygen in the cooling water is reduced by a degassing device. .

  The said structure WHEREIN: You may arrange | position the hydrogen-containing gas spray cooling device which sprays hydrogen-containing gas to the steel strip which carried out water cooling or air-water cooling downstream of a water cooling device or an air-water cooling device.

  Further, the cooling device in the cooling zone of the continuous heat treatment facility of the present invention is a degassing device in which the amount of dissolved oxygen in the cooling water is reduced by a degassing device in the cooling zone of the continuous heat treatment facility in which the steel strip is continuously passed and heat treated. A water-cooling device that cools the steel strip using water or an air-water cooling device that cools the steel strip is installed, and a hydrogen-containing gas is supplied to the steel strip that has been air-water cooled downstream of the water-cooling device or the steam-cooling device. A hydrogen-containing gas spray cooling device for spraying is provided.

  In the cooling of the steel strip according to the present invention, water cooling or air-water cooling using cooling water in which dissolved oxygen in the cooling water is reduced is used for water cooling of the steel strip so as not to interfere with chemical conversion treatment or plating treatment. Formation can be suppressed.

  In addition, by using cooling water in which dissolved oxygen in cooling water is reduced, even if an oxide film is slightly generated by cooling with cooling water, the oxide film can be further suppressed by subsequent hydrogen reduction.

  Moreover, since the cooling capacity is large, it is also suitable for the production of high-tensile steel.

  FIG. 1 is a view showing a cooling device for a continuous heat treatment facility according to the present invention, and this embodiment is an example of being arranged in a cooling zone of a continuous heat treatment facility.

  In FIG. 1, the steel strip 1 that has passed through the heating zone 2 and the soaking zone 3 shown in FIG. 2 and has undergone a predetermined heat treatment is turned by the deflector roll 16 and enters the cooling zone 4 and rises. On the entrance side of the cooling zone 4, a gas seal device 17 for blowing a gas is disposed to thermally shut off the soaking zone 3 and the cooling zone 4.

  In the cooling zone 4, a water cooling device that cools the steel strip 1 with water or an air-water cooling device 18 that cools the steel strip 1 is arranged. The air / water cooling device 18 is provided with an air / water injection nozzle, and sprays air on the steel strip 1. An air / water supply pipe 19 that supplies air / water is connected to the air / water cooling device 18. The air / water supply pipe 19 includes a gas supply pipe 21 that supplies gas by a blower 20 and a cooling water supply pipe that supplies cooling water. 22 are joining. As the gas supplied to the blower, an inert gas such as nitrogen is used.

The cooling water supply pipe 22 is provided with a deaeration device 24 for reducing dissolved oxygen in the cooling water supplied by the pump 23. As the degassing device 24 for reducing the dissolved oxygen amount in the cooling water, a known degassing device using N ₂ bubbling, gas-liquid separation membrane (decompression) or the like is used.

  A gas seal device 17 that blows gas is arranged downstream of the water cooling device or the air-water cooling device 18 so that the spray water does not go downstream.

  The steel strip 1 that has been subjected to the predetermined heat treatment in the continuous annealing facility is supplied with deaerated water in which the dissolved oxygen in the cooling water is reduced by the deaerator 24 in the cooling zone 4 to the air / water supply pipe 19 for water cooling or air. Cool with water. The water-cooled or air-water-cooled steel strip 1 is passed through the next overaging zone 14, the cooling zone 15, and the final cooling zone 12 in this order and heat-treated.

  At the time of manufacturing a hot dip galvanized steel strip, the steel strip 1 is introduced into a hot dip galvanizing pot 6 via a snout 5 and hot dip galvanized through the same steps as in the prior art.

  In the cooling zone 4, by forming water cooling or air-water cooling with deaerated water in which dissolved oxygen in the cooling water is reduced, formation of an oxide film can be suppressed so as not to hinder the chemical conversion treatment or the plating treatment.

  This embodiment is an example in which a hydrogen-containing gas spray cooling device 25 is disposed downstream of the water cooling device or the air-water cooling device 18 as indicated by a dotted line in FIG. In the case of water cooling or air-water cooling, even if an oxide film is generated by cooling with cooling water, the hydrogen-containing gas blowing device 18 can spray the hydrogen-containing gas and reduce the oxide film by hydrogen reduction. Therefore, the formation of the oxide film can be further suppressed so as not to hinder the chemical conversion treatment or the plating treatment.

It is a figure which shows the cooling device of the continuous heat processing equipment of this invention. It is the schematic which shows an example of the switch-type continuous heat processing equipment of a steel strip.

Explanation of symbols

1: Steel strip 2: Heating zone 3: Soaking zone 4: Cooling zone 5: Snout 6: Plating pot 7: Plating adhesion amount adjuster 8: Alloying device 9: Cooling device 10: Top roll 11: Air jet cooler type cooling Device 12: Final cooling zone 13: Line switching device 14: Overage zone 15: Cooling zone 16: Deflector roll 17: Air seal device 18: Air / water cooling device 19: Air / water supply piping 20: Blower 21: Gas supply piping 22: Cooling water supply pipe 23: pump 24: deaeration device 25: hydrogen-containing gas spray cooling device

Claims (6)

In the cooling method of the steel strip in the cooling zone of the continuous heat treatment equipment when continuously hot-dip galvanizing after the steel strip is continuously passed through and cooled in the cooling zone of the continuous heat treatment equipment,
A steel strip cooling method, characterized in that the steel strip is water-cooled or air-water cooled using deaerated water in which the amount of dissolved oxygen in the cooling water is reduced by a deaeration device.   2. The method for cooling a steel strip in a cooling zone of a continuous heat treatment facility according to claim 1, wherein the oxide film is reduced by hydrogen reduction by blowing a hydrogen-containing gas onto the steel strip cooled with water or air-water. In the cooling method of the steel strip in the cooling zone of the continuous heat treatment equipment that heat-treats the steel strip continuously through the plate,
The steel strip is water-cooled or air-water cooled using degassed water in which the amount of dissolved oxygen in the cooling water is reduced by a degassing device, and hydrogen reduction is performed by blowing a hydrogen-containing gas onto the water-cooled or air-water cooled steel strip. A method for cooling a steel strip in a cooling zone of a continuous heat treatment facility, characterized in that an oxide film is reduced at a temperature.   The amount of dissolved oxygen in the cooling water was reduced by a degassing device in the cooling zone of the continuous heat treatment equipment when the steel strip was continuously passed through and cooled in the cooling zone of the continuous heat treatment equipment and subsequently hot dip galvanized. A cooling device for a steel strip in a cooling zone of a continuous heat treatment facility, wherein a water cooling device for cooling the steel strip using deaerated water or an air-water cooling device for cooling water is provided.   A hydrogen-containing gas spray cooling device for blowing a hydrogen-containing gas to a water-cooled or air-water cooled steel strip downstream of the water cooling device or the air-water cooling device is disposed in the cooling zone of the continuous heat treatment facility. Item 5. A steel strip cooling device in a cooling zone of the continuous heat treatment facility according to Item 4.   A water cooling device for cooling a steel strip with water using deaerated water in which the amount of dissolved oxygen in the cooling water is reduced by a deaeration device in a cooling zone of a continuous heat treatment facility that heat-treats the steel strip through a continuous plate or An air-water cooling device for air-air cooling is disposed, and a hydrogen-containing gas spray cooling device for spraying hydrogen-containing gas to a water-cooled steel strip downstream of the water-cooling device or the air-water cooling device is provided. Steel strip cooling device in the cooling zone of continuous heat treatment equipment.

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