JP3204598B2 - Pickling method for titanium plate - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method of pickling a titanium plate, and more particularly, to a plate made of pure titanium or a titanium alloy (hereinafter, referred to as a plate).
While running the titanium plate), the steel plate is sequentially immersed in a pickling solution containing hydrofluoric acid and pickled, then the pickling solution adhered to the surface of the titanium plate is squeezed with a ringer roll, and then the titanium is washed by water spray. More particularly, the present invention relates to a method for pickling a titanium strip in a continuous pickling process line, wherein the pickling treatment is performed without causing brown colored spots (so-called pickling) on the surface of the titanium strip. Regarding how you can.

[0002]

2. Description of the Related Art In general, a titanium plate such as a titanium strip is manufactured by hot rolling or further cold rolling. However, this titanium plate is hardly shipped as it is, and after rolling, it is used to remove distortion. After being annealed in the air, the rolling and annealing scale and oxygen-enriched layer (a region where oxygen diffuses into titanium, which is hard and brittle and causes cracks in post-processing when left to stand) are partially removed by shot blasting or a salt bath. Then, it is cleaned with a pickling solution containing hydrofluoric acid, for example, nitric hydrofluoric acid.

[0003] However, in the above-mentioned pickling, a brown colored spot called so-called acid burn (hereinafter, referred to as acid burn) sometimes occurs on the entire surface of the titanium plate or locally. This acid burn is practically acceptable when the titanium plate is used as a structural material such as a heat exchanger. However, when it is used for a member that is visible to the public, such as a roof material or a curtain wall, the appearance is impaired. The generated material cannot be used as it is. The removal of the acid burn from the acid burn generating material is performed by re-pickling, and the acid burn existing before the re-pickling can be removed, but a new acid burn may occur during the re-pickling process. Fundamental measures are desired.

[0004] In such acid burning, devising a pickling solution,
That is, it can be prevented or removed by adding a chelating agent such as hydrogen peroxide, oxalic acid, and tartaric acid to hydrofluoric acid, which is described in, for example, JP-A-64-4491 and JP-A-1-23097. I have.

[0005]

However, in order to prevent the occurrence of acid scorch during pickling of a titanium plate, Japanese Patent Application Laid-Open No. 64-4491 has been proposed.
No., as described in JP-A-1-23097,
Applying the method of adding a chelating material to hydrofluoric acid has the following problems. That is, the technology described in these publications is a method for producing a colored titanium material, in which a pickling solution obtained by adding a chelating material to hydrofluoric acid is used for pretreatment for coloring, and the amount thereof may be relatively small. On the other hand, in pickling a titanium plate such as a titanium strip, an extremely large amount of pickling liquid is required as compared with the above-described pre-coloring treatment. Therefore, mixing a chelating material with hydrofluoric acid requires a waste liquid treatment method and a large cost. It causes problems such as rising. Also, the problem of pickling bath management,
The problem of the corrosion resistance of the pickling line used so far, and also the legal problem such as the approval of the use of a large amount of chelating material arise. From these points, it is almost impossible to add a chelating material to the pickling solution in a pickling process of a titanium plate, particularly a continuous pickling process line of a titanium strip for mass production.
There are too many problems to apply.

The present invention has been made in view of such circumstances, and has as its object to solve the above-mentioned problems.
An object of the present invention is to provide a method for pickling a titanium plate which has no problems as in the case of adding a chelating agent to a pickling liquid and can prevent or reduce the occurrence of acid burning in pickling of a titanium plate. It is.

[0007]

In order to achieve the above object, a method for pickling a titanium plate according to the present invention has the following configuration .

Namely, pickling method according to claim 1, while traveling titanium plate, was immersed sequentially in pickled pickling solution containing hydrofluoric acid, wringer roll deposition solution of a titanium plate surface In the method for pickling a titanium plate, which is then washed by water spray, water is sprayed on the surface of the titanium plate between a position where the titanium plate comes out of the pickling solution and a ringer roll. This is a method for pickling a titanium plate.

[0009] The pickling method according to claim 2, while traveling titanium plate, after pickling sequentially immersed into the pickling solution containing hydrofluoric acid, wringer roll attachment pickling solution of a titanium plate surface The method of pickling a titanium plate, wherein the water is supplied to the surface of the ringer roll, followed by washing with a water spray.

In the pickling method according to the third aspect, the titanium plate is immersed in a pickling solution containing hydrofluoric acid while the titanium plate is running, followed by pickling, and the liquid adhering to the surface of the titanium plate is squeezed with a ringer roll. Then, in the pickling method for a titanium plate, wherein the titanium plate is washed from the pickling solution by a water spray.
1m or more from the position to the position
The pickling liquid in the area up to the position is
Flow at right angles to the flow direction: 10 cm / sec or more ,
Spray water into the titanium plate surface at pickling method according to claim 1, 2 or 3 to be carried out in the supply of water to the wringer roll surface at pickling method according to claim 2 It is characterized by the following.

[0011]

The cause of the occurrence of acid burning in pickling of a titanium plate has not been known so far, and some known documents state that "titanium fluoride is formed at the time of pickling and this is the cause (Japanese Unexamined Patent Publication No. -123097), "Since the activated titanium surface after the oxide film is removed by pickling is re-oxidized by the oxidizing action of nitric acid (Japanese Patent Application Laid-Open No. 64-4491)" and the like. There was only a notation.

The inventors of the present invention have conducted intensive studies and investigated the causes of acid burning. As a result, the cause of the acid burn was elucidated. That is, the pickling produces titanium ions and titanium fluoride ions in the pickling solution, and these ions are generated during and immediately after the pickling (when the titanium plate comes out of the pickling solution, the pickling solution still remains on the surface). Reacts with the water or dissolved oxygen in the pickling solution to form a titanate, which is adsorbed on the titanium surface to form an oxide film.
This oxide film is the true nature of the acid burn, and the film is formed when the titanium plate is in the pickling solution as described above and also in a state where the pickling solution adheres to the surface of the titanium plate after the pickling. It was found that when drying was performed while the pickling solution was adhered to the surface, titanium ions and titanium fluoride ions were concentrated in the process, so that acid burning was significantly generated.

From the above, as a method for preventing the occurrence of acid burning, it is effective to remove titanium ions and titanium fluoride ions present near the surface of the titanium plate as soon as possible during and after pickling. Can prevent or reduce the occurrence of acid burning in pickling of a titanium plate.

Based on the above findings, the present inventors, as a first invention, sequentially dipped and pickled in a pickling solution containing hydrofluoric acid while running the titanium plate, squeezing the deposition solution with wringer roll, then, the pickling method of the titanium plate to perform washing with water spray, before
The position where the titanium plate comes out of the pickling solution and the ringer roll
In the meantime, a method for pickling a titanium plate (a method for pickling according to claim 1), wherein water is sprayed on the surface of the titanium plate, has been invented.

[0015]

[0016]

The first invention (the pickling method according to claim 1 )
Is Ru der particularly those based on that clarifies the cause of acid burn. According to the present invention, by spraying water on the surface of the titanium plate as described above, the pickling solution adhering to the surface of the titanium plate after the pickling is washed off. The concentration drops dramatically,
The surface of the titanium plate is prevented from drying while the pickling liquid remains attached, and as a result, acid burning does not occur.

Here, when spraying water on the surface of the titanium plate as described above, the amount of water is desirably 40 liters / h or more, so that acid burning can be more reliably prevented. Rather than spraying water from one nozzle, it is desirable to spray water from several nozzles and to disperse it to some extent in the width direction of the titanium plate, so that uneven pickling can be prevented uniformly. Also, by mixing air into water and spraying it in the form of a mist, uneven pickling can be prevented uniformly.

[0019] The second invention (the pickling method according to claim 2 ) provides:
While running the titanium plate, after successively immersing in a pickling solution containing hydrofluoric acid and pickling, the pickling solution adhered to the surface of the titanium plate is squeezed with a ringer roll, and then the titanium plate is cleaned by water spray. In the pickling method, since water is supplied to the surface of the ringer roll, drying after passing through the ringer roll can be prevented, and thus acid burning can be prevented. Further, the present invention is effective in that the pickling solution adhered to the surface of the titanium plate is washed away. That is, the pickled titanium plate enters the ringer roll while the pickling liquid adheres to the surface, where the pickling liquid on the surface is squeezed out and then washed by water spray. Since the washing liquid cannot be completely removed, the pickling liquid is present in a very thin film state on the titanium plate surface after passing through the ringer roll, and is therefore very easy to dry, which causes acid burning (Ringer). When water is not supplied to the roll surface). In contrast,
When water is supplied to the surface of the ringer roll, drying after passing through the ringer roll can be prevented, so that acid burning can be prevented, and furthermore, the pickling solution is washed off, and the concentration of titanium ions and titanium fluoride ions is drastically reduced. In addition, acid burning is more reliably prevented.

In supplying water to the surface of the ringer roll, it is desirable to increase the amount of water in order to prevent acid scorching, and it is preferable to uniformly supply water to the entire surface of the ringer roll to prevent acid scorching and pickling. It is preferable in terms of preventing unevenness. As a method of supplying water to the ringer roll surface, for example, a method of spraying water on the ringer roll, or in the case of a lower ringer roll, a water pan below the roll so that a part of the roll is soaked. And the like.

The third invention (the pickling method according to claim 3 ) is
While traveling titanium plate, after pickling sequentially immersed into the pickling solution containing hydrofluoric acid, squeezing the deposition solution of a titanium plate surface wringer roll, then, when performing cleaning with water spray, the acid From the position where the titanium plate comes out from the washing liquid
Area up to a position 1m or more in the direction of entry of the titanium plate
The pickling liquid in the area in a direction perpendicular to the running direction of the titanium plate.
Speed: flow at 10 cm / sec or more, first flow as described above
Two or more of the spraying of water on the surface of the titanium plate according to the invention and the supply of water to the surface of the ringer roll according to the second invention are simultaneously performed. ADVANTAGE OF THE INVENTION According to this invention, generation | occurrence | production of an acid burn can be prevented more reliably.

As described above, the pickling liquid is made to flow.
From the surface of the titanium plate during pickling.
Titanium ion can be efficiently removed,
Reaction between ions and water or dissolved oxygen in the pickling solution
There is no formation of tanides and the titanic titanium
Oxide film (acid burn) is formed by adsorption on
No. Here, when the pickling liquid flows, the pickling liquid flows.
The direction of movement was perpendicular to the running direction of the titanium plate.
Will transfer titanium ions and titanium fluoride ions in this direction.
If these ions are on the titanium plate surface at the shortest distance
Removal efficiency is good, and in the other direction,
Removal efficiency is reduced and acid burns occur
Because. In addition, the flow rate of the pickling liquid flow should be 10 cm / sec or more.
The reason is that when the flow rate is less than 10 cm / sec,
Force is weakened and the removal of the above ions becomes insufficient.
This is because acid burning occurs. Furthermore, acid
The titanium plate comes out of the pickling liquid in the area where the washing liquid flows.
From the position (hereinafter referred to as the "outside position") to the position
Up to 1m in the entrance direction (hereinafter, 1m forward)
Area (hereinafter referred to as a specific area)
To the exit side position (hereinafter, the rear 1m area).
The oxide scale on the titanium plate surface is almost completely removed
In the rear 1 m area, the titanium and the pickling solution are most reactive.
In response, a large amount of titanium ion and titanium fluoride ion are formed
Therefore, the region including the rear 1m region (that is, the region
The above-mentioned ion is removed by flowing the pickling liquid in the specific area)
It is effective to use a narrow area within the rear 1m area
Insufficient removal of the above ions, resulting in acid burning
This is because you will be nervous. The uniformity of the pickling solution composition
And how to move the pickling liquid to improve the uniformity of the plate thickness.
Partially facing the direction (that is, the
(Partial opposition) is included in the scope of the present invention.
You.

In any of the above-mentioned present invention, a chelate is added to the pickling solution.
No material is added, and it is used to prevent acid burning.
For this reason, no new additives are added to the pickling solution.
Apply the method of adding a chelating agent to the pickling solution for pickling
In the pickling of titanium plate
Acid burning can be prevented. In addition, the current acid
There is no need to change the washing liquid, and the titanium plate
Spray water on the surface and supply water to the ringer roll surface.
Both supply and pickling liquid flow should be done by simple means
Therefore, the present invention can be easily performed using the current pickling solution.
There is an advantage that it can be performed.

[0024]

(Example 1) A plate manufactured by hot rolling and cold rolling a titanium slab.
Thickness: 3mm, board width: 1200mm titanium strip
Il) heating atmosphere: air, heating temperature: 750 ℃ Dewarping
Annealed. About the titanium plate thus obtained,
Using a continuous pickling line shown in Fig. 1, a continuous acid for 24 hours
The washing treatment was performed as follows.

The traveling speed of the titanium plate 2 is 5 m / min (min).
While running, in pickling liquid 8 in pickling tank 3 with a total length of just over 9 m
And then pickled, then the outlet position A and Ringerlo
Between the water spray nozzle 11 and the
After spraying water on both sides of titanium plate, adhesion of titanium plate 2 surface
The liquid is squeezed with ringer rolls 5 and 6, and then sprayed with water
Washing with 14 and then ringer roll 15 with titanium plate
2 After squeezing the washing water on the surface,
went. Then, the titanium plate 2 after drying is observed on the observation table 7.
Then, the degree of acid burning was evaluated.

Here, the pickling liquid 8 contained 1
with wt% HF-12wt% HNO ₃ mixed solution. Water sp
The amount of water (total water, not individual nozzle flow)
Volume), spray nozzle position and number, spray form
(Normal water spray, mix air with water to make mist
(Spray) was varied as shown in Table 1. Note that FIG.
Reference numeral 4 denotes a dipping roll.

The results of the evaluation of the degree of occurrence of the acid burn are shown in the table.
It is shown in FIG. This evaluation is a 6-point scale, with XX marks
Is the most remarkable in the degree of acid burning, followed by × → △ →
○ The degree of acid scorch occurrence is smaller as
And ◎ indicates that no acid burn occurred.
It shows.

[0028]

As can be seen from Table 1 , when water is sprayed as described above (Nos. 1 to 20), the degree of acid burning is reduced as compared with the case where water is not sprayed (No. 21). Those N
o. In the case of Nos. 17-20, spray water volume: 10
3030 liters / h, which is a degree that acid burning is slightly reduced. On the other hand, the spray water volume is
Since the rate is as high as 40 liters / h or more, the occurrence of acid burning is small and excellent.

Focusing on Nos. 1 to 7 among these Nos. 1 to 16, Nos. 1 to 3 had a degree of acid scorch due to the use of one spray nozzle. In the case of No. 7, since two or three spray nozzles were used, water was more evenly distributed on the surface of the titanium plate, which prevented not only the drying of the surface of the titanium plate, but also the titanium ion and the titanium fluoride ion on the surface of the titanium plate. Can be uniformly removed, and as a result, the degree of occurrence of acid burning is reduced. In addition, comparing No. 1 to 7 and No. 8 to 14, No. 8 to 14 has a larger spray water amount, so that the effect of preventing drying of the titanium plate surface and the effect of removing titanium ions and titanium fluoride ions. And the degree of acid burning is reduced. Nos. 15 and 16 were obtained by mixing air with water and spraying them in the form of a mist, and as in the case of ordinary water spray, the effect of preventing acid burn was obtained.

[0031] (Example 2) Continuous pickling line according to the second embodiment shown in FIG. Water spray on the titanium plate surface by the water spray nozzle 11 as described above
Without playing , water is sprayed on the upper ringer roll 5 by the water spray nozzle 18, while a water pan 17 (always filled with fresh water 19) is provided below the lower ringer roll 6, and the roll is always rolled. 6 Water was supplied to the surface of the ringer roll so that the lower part was immersed in water 19. Except for this point, the same titanium plate was subjected to continuous pickling treatment in the same manner as in Example 1, and the degree of occurrence of acid burning was evaluated. As a result, it was ○ or ◎, and the effect of preventing acid burning was recognized. This is because by constantly wetting the surface of the ringer roll with water, it was possible to prevent the surface of the titanium plate from drying after passing through the ringer roll and preventing the pickling liquid adhering to the surface of the ringer roll from re-adhering to the surface of the titanium plate.

Embodiment 3 FIG. 3 shows a continuous pickling treatment line according to Embodiment 3 . (1)
Flow of pickling solution 8, (2) Example 1 and water spray into the titanium plate both sides by the same water spray nozzle 11, (3) Example 2
In the same manner as in Example 1, continuous pickling was carried out in the same manner as in Example 1 except that two or more of the water supplies to the surfaces of the ringer rolls 5 and 6 were combined as shown in Table 2. The degree of occurrence of burning was evaluated. Table 2 shows the results. No.1
2 to 16 are performed for comparison, and one of (1) to (3) is used instead of the combination. O indicates that acid scorch is less likely to occur and is good. However, N was obtained by combining two or three of the above (1) to (3).
o.1-11 are excellent. That is, in the case of Nos. 1 to 11, not only the occurrence of acid scorch is not recognized at all, but also the surface properties indicated by ◎ ◎ mark of a level superior to ◎ mark,
It was better than 11 cases. In the case of Nos. 17 and 18,
Although the above (1) and (2) are combined, the spray water volume in (2) is 20 liters / h, which is small, and is marked X, which slightly reduces the degree of acid burning. It is just being done.

The flow of the pickling liquid 8 in the above (1) is
The pickling solution is pickled from the pickling solution discharge port 13 through
By discharging the solution into the pickling solution in a predetermined area in the washing tank 3
went. At this time, the flow area, flow direction, and flow of the pickling liquid 8
The moving speed (flow rate) was changed as shown in Table 2. Among them,
The flow area is the position where the titanium plate enters the pickling liquid (hereinafter, the entry side
Position) Divide the distance 9m from B to the exit position A by 9
The side position A is set to the 0 m position, and the entry side position B is set to the 9 m position.
Indicated by the interval (range). That is, in Table 2,
For example, 0 to 1 is the distance from the exit position A to the 1m position in front of the exit position.
Range (area corresponding to the rear 1m area), 3 to 6 are on the outgoing side
In the area from the front 3m position to the exit side position 6m front
It means that the pickling liquid was fluidized. Pickling flow direction
Direction of pickling liquid discharge from liquid discharge port to titanium plate surface
In each case, make the titanium plate parallel to the running direction 1 of the titanium plate.
The discharge of the titanium plate in the running direction 1
It is indicated by the angle 10 formed by the flow direction 12 of the pickling liquid thus obtained. In FIG.
Numeral 4 indicates a dipping roll.

[0034]

[Table 1]

[0035]

[Table 2]

[0036]

The method for pickling a titanium plate according to the present invention has the above-mentioned structure and functions, and a new pickling solution is used to prevent the occurrence of pickling (brown colored spots). It does not have the problems as in the case where the means for adding a chelating material is applied, and can prevent or reduce the occurrence of acid scorching in pickling of a titanium plate by simple means, and has excellent surface properties. This has the effect that a titanium plate can be manufactured.

[Brief description of the drawings]

FIG. 1 is a diagram showing an outline of a continuous pickling treatment line according to Example 1, wherein FIG. 1 (A) is a plan view and FIG. 1 (B) is a front view.

FIG. 2 is a diagram showing an outline of a continuous pickling treatment line according to a second embodiment, where FIG. 2 (A) is a plan view and FIG. 2 (B) is a front view.

FIG. 3 is a diagram showing an outline of a continuous pickling treatment line according to a third embodiment, in which (A) is a plan view and (B) is a front view.

[Explanation of symbols]

1-running direction of titanium plate, 2-titanium plate, 3-pickling tank,
4-dip roll, 5-upper ringer roll, 6-lower ringer roll, 7-observation table, 8-pickling liquid, 9-pump,
10--Angle indicating pickling liquid flow direction, 11--Water spray nozzle, 12--Pickling liquid flow direction, 13--Pickling liquid outlet, 14--Water spray, 15--Ringer roll, 16 --Drier, 17--water pan, 18--water spray nozzle, 19--water, A--outside position,
B--entrance position.

Continuation of the front page (72) Inventor Shinichi Naramoto 1 Kanazawa-cho, Kakogawa-shi, Hyogo Kobe Steel, Ltd. Kakogawa Works (56) References JP-A-60-243290 (JP, A)

Claims (3)

(57) [Claims] 1. While the titanium plate is running, it is sequentially immersed in a pickling solution containing hydrofluoric acid and pickled, followed by squeezing the liquid adhering to the surface of the titanium plate with a ringer roll, and then washing with a water spray. The pickling method for a titanium plate, wherein the pickling is performed.
Between the position where the titanium plate comes out of the liquid and the ringer roll
A method of pickling a titanium plate , wherein water is sprayed on a surface of the titanium plate. 2. While the titanium plate is running, it is sequentially immersed in a pickling solution containing hydrofluoric acid and pickled, followed by squeezing the pickling solution adhered to the surface of the titanium plate with a ringer roll, and then washing with a water spray. in pickling a titanium plate which performs the
A pickling method for a titanium plate, comprising supplying water to the surface of a ringer roll . 3. While running the titanium plate, it is sequentially immersed in a pickling solution containing hydrofluoric acid and pickled, followed by squeezing the liquid adhering to the surface of the titanium plate with a ringer roll, and then washing with a water spray. The pickling method for a titanium plate, wherein the pickling is performed.
From the position where the titanium plate comes out of the liquid,
Pickling liquid in the area up to a position 1m or more in the direction of entry of the plate,
Flow velocity perpendicular to the running direction of the titanium plate: 10cm / se
c Flow the above, titanium plate from the pickling liquid
Titanium plate surface between exit position and ringer roll
Spraying water on the surface of the ringer roll
A method for pickling a titanium plate, wherein two or more of supplying water are performed simultaneously .