JPH10265986A - Method for continuously annealing and pickling cold rolled stainless steel strip and device therefor - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a method and a device for continuously annealing and pickling a cold rolled stainless steel strip by which a stainless steel sheet excellent in surface properties can be manufactured with a simple device by reducing used utility consumption such as water, steam. SOLUTION: In the method for continuously annealing and pickling the cold rolled stainless steel strip, the cold rolled stainless steel strip 11 is cleaned with alkali, then spray cleaning is executed thereto with an acidic aq. soln. 17a and the cleaned steel strip is subjected to annealing and pickling. The device for continuously annealing and pickling the cold rolled stainless steel strip has a dewaxing device, an annealing furnace and a pickling device of the steel strip and the dewaxing device has an alkali cleaning device 12 and an acidic aq. soln. spraying device 30 disposed as a postprocess of the alkali cleaning device.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a continuous annealing and pickling method and a continuous annealing and pickling equipment for a cold-rolled stainless steel strip, and more particularly to manufacturing a cold-rolled stainless steel strip having excellent surface properties. The present invention relates to a method and an apparatus for continuous annealing and pickling of a cold-rolled stainless steel strip capable of being subjected to heat treatment.

[0002]

2. Description of the Related Art Generally, in a continuous annealing and pickling line for a stainless steel strip after cold rolling, the steel strip is washed with an alkaline aqueous solution in order to remove rolling oil adhering during cold rolling before annealing. Pretreatment (hereinafter also referred to as degreasing) is performed (for example, JP-A-6-2177).

FIG. 2 is a side view showing an example of a continuous annealing and pickling facility for a stainless steel strip after cold rolling. In FIG. 2, 1a and 1b are pay-off reels, 2 is a welding machine, 3 is a degreasing device, 4 is an entrance looper, 5 is an annealing furnace, 6 is a cooling zone, 7
Denotes a pickling facility, 8 denotes an outlet looper, 9 denotes a shear, 10 denotes a tension reel, 11 denotes a stainless steel strip, and f denotes a direction in which the steel strip passes.

[0004] The cold-rolled stainless steel strip (hereinafter also referred to as the steel strip) 11 is welded at the rear end of the preceding coil and the front end of the subsequent coil by the welding machine 2 to form a continuous steel strip and continuously annealed and acidified. Washing equipment is passed through. After the rolling oil adhering at the time of cold rolling is removed by the degreasing device 3, the steel strip 11 reaches the annealing furnace 5 through the entry-side looper 4.

[0005] After the steel strip annealed in the annealing furnace 5 is cooled in the cooling zone 6, the scale generated at the time of annealing is removed in the pickling equipment 7, passes through the outlet looper 8, and passes through the shear 9.
Is wound around the tension reel 10 in a desired length. Next, FIG. 3 is a side view showing a conventional degreasing device arranged as the degreasing device 3 of FIG.

In FIG. 3, reference numeral 11 denotes a stainless steel strip, 12 denotes an alkaline cleaning device (: degreasing tank), 12a denotes an alkaline aqueous solution, 13 denotes a ringer roll, 14 denotes a first washing spray tank, 14
a indicates a spray header, 14b indicates a water supply pipe, 15 indicates a second washing spray tank, 15a indicates a spray header, 15b indicates a water supply pipe, and 16 indicates a dryer. Stainless steel strip after cold rolling
Reference numeral 11 denotes an alkaline aqueous solution 12
a, after the rolling oil adhering during the cold rolling is removed, the first water-washing spray tank 14 and the second water-washing spray tank 15 are used to remove the alkali component adhering to the steel sheet. After being dried by the dryer 16 and conveyed to the annealing furnace 5 shown in FIG. 2, after being annealed, it is descaled by the pickling equipment.

However, according to such a method, when the steel plate is not sufficiently washed or washed with hot water in the first washing spray tank 14 and the second washing spray tank 15 after the alkali washing, Na ⁺ is added to the steel strip surface. Alkaline components remain, especially in the case of austenitic stainless steel,
There is a problem that the steel plate appears as a pattern on the surface of the steel sheet after pickling, which has been a factor of reducing the quality of the product.

Further, in order to sufficiently perform the washing with the above-mentioned water or hot water, a large amount of water and a large amount of steam for raising the temperature of the water are required. Furthermore, in the continuous annealing line, when welding the steel strip of the leading coil and the succeeding coil on the line entrance side, the entrance side line is stopped, during which the part with the alkali component adhered is dried and solidified. However, there has been a problem that the above-mentioned cleaning with water or hot water cannot be completely cleaned, and the above-mentioned defects in the surface properties of the steel sheet occur.

[0009]

DISCLOSURE OF THE INVENTION The present invention solves the above-mentioned problems of the prior art, and reduces the use of water, steam and the like by using a stainless steel sheet having excellent surface properties, and uses simple equipment. It is an object of the present invention to provide a continuous annealing and pickling method and a continuous annealing and pickling facility for a cold-rolled stainless steel strip that can be manufactured.

[0010]

According to a first aspect of the present invention, a cold rolled stainless steel strip is subjected to alkali cleaning, then spray cleaning with an acidic aqueous solution, and the cleaned steel strip is annealed and pickled. A continuous annealing and pickling method for a cold-rolled stainless steel strip. According to a second aspect of the present invention, the cold-rolled stainless steel strip is subjected to alkali cleaning, then spray cleaning with an acidic aqueous solution, and after the cleaning, further washing with water, and annealing and pickling the washed steel strip. This is a method for continuous annealing and pickling of a cold-rolled stainless steel strip.

A third invention is a continuous annealing and pickling facility for a cold-rolled stainless steel strip having a steel strip degreasing apparatus, an annealing furnace and a pickling facility, wherein the degreasing apparatus comprises an alkali cleaning apparatus. A continuous annealing and pickling apparatus for a cold-rolled stainless steel strip, comprising: an acidic aqueous solution spraying apparatus provided as a post-process of the alkali cleaning apparatus. 4th
The invention is a continuous annealing and pickling equipment for a cold-rolled stainless steel strip having a steel strip degreasing apparatus, an annealing furnace and a pickling facility, wherein the degreasing apparatus is an alkali cleaning apparatus and the alkali cleaning apparatus. Continuous annealing and pickling equipment for a cold-rolled stainless steel strip, comprising: an acidic aqueous solution spraying device provided as a post-process, and a water washing device provided as a post-process of the acidic aqueous solution spraying device. It is.

[0012]

BEST MODE FOR CARRYING OUT THE INVENTION Hereinafter, the present invention will be described in more detail. The present inventor has conducted intensive studies in order to solve the above-mentioned problems of the prior art, and found that the alkali removal of the stainless steel strip depends on the conventional washing with water or hot water provided as a post-process of the alkali washing apparatus. Instead of washing with an aqueous acid solution, the inventors have found that the following excellent effects can be obtained, and have reached the present invention.

The deterioration of the surface quality of the stainless steel plate can be prevented. : Quickly neutralize alkali on the steel strip surface by using spray method as washing method with acid aqueous solution,
The cleaning effect in the water washing device or the hot water washing device in the subsequent process can be increased. As a result, the washing tank using the acidic aqueous solution may be simple and small-scale equipment, and can be industrially easily applied.

With the improvement of the washing effect in the water washing device or the hot water washing device in the post-process described above, water,
Steam usage can be reduced. FIG. 1 is a side view showing an example of a degreasing apparatus in a continuous annealing and pickling facility for a cold-rolled stainless steel strip according to the present invention. The degreasing device according to the present invention illustrated in FIG. 1 is provided, for example, as a degreasing device 3 of a continuous annealing / pickling facility shown in FIG.

In FIG. 1, reference numeral 17 denotes an acidic aqueous solution tank or acid solution storage tank, 17a denotes an acidic aqueous solution or acid solution, 18 denotes an acid solution storage tank, 19 denotes a water supply pipe, 20 denotes a pH meter, 21 denotes an acid solution supply amount and water. Supply amount control device, 22 is an acid solution supply amount control valve, 23 is a water supply amount control valve, 24 is a pump, 30 is an acidic aqueous solution spray device for cleaning steel strip, 30a is a spray header, and 30b is an acidic aqueous solution Supply pipe, 31 is a washing spray tank, 31a is a spray header, 31b is a water supply pipe, and other symbols are shown in FIG.
Indicates the same content as.

The pH of the acidic aqueous solution 17a supplied to the acidic aqueous solution spraying device 30 is controlled by an output from the pH meter 20.
A control valve 22 for controlling the supply amount of the acid solution via the control valve 21 and a control valve 23 for controlling the water supply amount
It is performed by adjusting the opening degree. Examples of the acid of the acidic aqueous solution or acid solution in the present invention include inorganic acids such as sulfuric acid, hydrochloric acid, nitric acid, and hydrofluoric acid, acetic acid, oxalic acid, and water-soluble organic acids such as tartaric acid, and mixed acids thereof. There is no restriction.

The pH of the acidic aqueous solution is preferably 6 or less, and more preferably 1 to 4. This is because when the pH exceeds 6, the effect of neutralizing and cleaning the alkali of the steel sheet is reduced, the effect of suppressing the generation of patterns on the steel sheet surface after annealing is reduced, and when the pH is less than 1. This is because the acid content may remain even after water washing in a later step, and rust may be generated on the steel sheet surface after annealing.

Although the type of stainless steel strip to be used in the present invention is not particularly limited, the present invention is more preferably applied to cold rolling in which an austenitic stainless steel strip is passed as the steel strip 11. Continuous annealing of stainless steel strip
Used as pickling method and equipment. This is because according to the present invention, the occurrence of a pattern on the steel sheet surface after continuous annealing and pickling of the austenitic stainless steel strip, which is particularly problematic, can be effectively suppressed.

In the degreasing apparatus according to the present invention shown in FIG. 1, the cold-rolled stainless steel strip 11 is immersed in an alkaline aqueous solution 12a in an alkaline cleaning apparatus 12 to remove rolling oil adhering during cold rolling. You. The steel strip from which the rolling oil has been removed is neutralized and removed of the alkali component adhering to the steel sheet in the acidic aqueous solution spraying device 30, and then, in the washing spray tank 31, the residual and surplus of the neutralized alkali component. The alkali and excess acid are removed and cleaned.

Next, the cleaned steel strip 11 is supplied to a dryer 16.
And transferred to the annealing furnace 5 shown in FIG.
It is descaled in the pickling facility 7. According to the present invention described above, in the first water washing device or hot water washing device after alkali washing, instead of water washing or hot water washing, an acidic aqueous solution or an acid solution is spray-sprayed on the surface of the steel sheet, thereby quickly reducing the steel. Neutralizing and washing the alkali content of the belt surface, and washing the steel sheet after the washing with water or hot water, a beautiful steel strip free of alkali content on the surface can be obtained. Could be solved.

The steel strip obtained by the above-described degreasing apparatus according to the present invention can suppress the generation of patterns on the steel sheet surface due to the residual alkali even when performing annealing and pickling in a later step. Steel strip is obtained. Furthermore, according to the present invention,
Since a simple apparatus called spray cleaning can be used, and the spray amount of the aqueous solution can be significantly reduced as compared with the water spray method or the like, the equipment scale can be small.

That is, according to the present invention, the above-described excellent effects can be obtained without using a large-scale apparatus such as an acid immersion tank and an electrolytic pickling tank, and the present invention can be easily applied industrially. In addition, as a result of using the spraying method of the acidic aqueous solution, the water washing effect can be obtained even if the amount of water used and the amount of steam used in the water washing or hot water washing in the subsequent step are reduced. As described above, according to the present invention, a stainless steel sheet having excellent surface properties can be manufactured with simple equipment by reducing the amount of utility such as water and steam.

Further, the acidic aqueous solution spraying apparatus according to the present invention can be installed on existing equipment by simple modification without providing a new washing tank. It is possible to manufacture a stainless steel plate excellent in quality.

[0024]

EXAMPLES The structure of the present invention and the effects obtained therefrom will be specifically described below based on examples. In the continuous annealing and pickling equipment of the cold rolled stainless steel strip shown in FIG. 2 provided with the degreasing apparatus according to the present invention shown in FIG. 1, the continuous annealing and pickling test of the austenitic stainless steel strip [: SUS304] was performed. went.

The test conditions were as follows. (1) [Alkaline aqueous solution of alkali washing device] Alkali used: NaOH Alkaline concentration: 2.0 wt% Liquid temperature: 60 ° C (2) [Spray acidic aqueous solution of acidic aqueous solution spraying device] Acid solution: HNO ₃ acidic aqueous solution pH: 3 Liquid temperature: 60 ° C (3) [Spray water in the water-washing spray tank] Liquid temperature: 60 ° C As a result, the annealed and pickled stainless steel sheets produced in this test are steel sheets due to alkali residues that have conventionally occurred. The generation of patterns on the surface was significantly suppressed.

Further, the spray water in the washing spray tank is used for about 30 minutes.
%, And the amount of steam for raising the temperature of the washing water can be reduced in accordance with the amount of spray water used.

[0027]

According to the present invention, the cold-rolled stainless steel strip is washed with an alkali, then sprayed with an acidic aqueous solution or an acid solution to quickly neutralize the alkali on the steel strip surface.
After cleaning, the steel strip is washed with water or hot water to obtain a beautiful steel strip with no alkali content on the surface, and after annealing and pickling, the generation of patterns due to the residual alkali content Can be suppressed.

Further, it is possible to reduce the amount of cleaning water or hot water used, and it is possible to reduce the amount of steam used when using hot water. Further, according to the present invention, the above-described effects can be obtained by simple remodeling of existing equipment without providing a new cleaning tank.

[Brief description of the drawings]

FIG. 1 shows the continuous annealing of the cold-rolled stainless steel strip of the present invention.
It is a side view which shows an example of the degreasing apparatus in a pickling installation.

FIG. 2 is a side view showing an example of continuous annealing and pickling equipment for a stainless steel strip after cold rolling.

FIG. 3 is a side view showing a conventional degreasing device.

[Explanation of symbols]

 1a, 1b Payoff reel 2 Welding machine 3 Degreasing device 4 Inlet looper 5 Annealing furnace 6 Cooling zone 7 Pickling equipment 8 Outlet looper 9 Shar 10 Tension reel 11 Stainless steel strip 12 Alkaline cleaning device (: degreasing tank) 12a Alkaline aqueous solution 13 Ringer roll 14 1st rinsing spray tank 14a, 15a, 30a, 31a Spray header 14b, 15b, 19, 31b Water supply piping 15 2nd rinsing spray tank 16 Dryer 17 Acidic aqueous solution tank, acid solution storage tank 17a Acidic solution, acid solution 18 Acid solution storage tank 20 pH meter 21 Controller 22, 23 Control valve 24 Pump 30 Acid solution spray device 30b Acid solution supply pipe 31 Rinse spray tank f Steel strip passing direction

Claims (4)

[Claims] 1. A cold-rolled stainless steel strip characterized by subjecting a cold-rolled stainless steel strip to alkali cleaning, spray-washing with an aqueous acidic solution, and annealing and pickling the washed steel strip. Annealing and pickling method. 2. The cold-rolled stainless steel strip is washed with alkali, spray-washed with an acidic aqueous solution, washed with water, washed with water, and the washed steel strip is annealed and pickled. Method of continuous annealing and pickling of cold rolled stainless steel strip. 3. A continuous annealing and pickling equipment for a cold-rolled stainless steel strip having a steel strip degreasing apparatus, an annealing furnace and a pickling facility, wherein the degreasing apparatus includes an alkali cleaning apparatus and the alkali cleaning apparatus. An apparatus for continuously annealing and pickling a cold-rolled stainless steel strip, comprising an acidic aqueous solution spraying device provided as a post-process of the device. 4. A continuous annealing and pickling facility for a cold-rolled stainless steel strip having a steel strip degreasing apparatus, an annealing furnace and a pickling facility, wherein the degreasing apparatus includes an alkali cleaning apparatus and the alkali cleaning apparatus. Continuous annealing and pickling of a cold-rolled stainless steel strip, comprising: an acidic aqueous solution spray device provided as a post-process of the device; and a water washing device provided as a post-process of the acidic aqueous solution spray device. Facility.