JP2002012931A - Titanium plate excellent in surface properties and method for producing the same - Google Patents

Abstract

(57) Abstract: Provided is a hot rolled titanium sheet having a polished surface having a uniform surface property throughout the inside of the sheet thickness, and a method for producing the same. The titanium hot rolled sheet for a surface member of an electrolytic deposition drum is a titanium plate containing 0.015 to 0.120% by mass of oxygen and having no crystal grains exceeding 100 μm in the entire cross section. This hot rolled titanium sheet has a hot rolling end temperature of 20.
After rolling at 0 to 750 ° C., the cooling rate at the center of the rolled sheet is cooled at 10 ° C./min or more, and then heat-treated in a temperature range of 550 to 700 ° C. for a holding time satisfying the following formula. Can be manufactured. 1.2 ≦ T / t ≦ 15 where t is the thickness of the titanium material (mm) and T is the holding time (mi)
n).

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an inexpensive hot rolled titanium sheet having excellent surface properties and used for a surface member of an electrolytic deposition drum for producing a metal foil such as copper or nickel by an electrolytic deposition method. To a method for producing

[0002]

2. Description of the Related Art In recent years, with the rapid development of electronic devices and the like, metal foils such as copper and nickel used for these devices have been in increasing demand and strict requirements for quality. Requirements) are increasing.

[0003] These metal foils are obtained by depositing copper or nickel on the surface of a metal drum (hereinafter referred to as "electrolytic drum") from a copper or nickel electrolytic solution, and continuously depositing the deposited foil. Manufactured by recovery. For this reason, since the surface shape of the electrolytic drum is transferred to the surface of the metal foil, the surface property of the metal foil depends on the quality of the surface property of the electrolytic drum.

[0004] In this electrolytic drum, a titanium material is frequently used from the viewpoint of corrosion resistance with an electrolytic solution. For example, a titanium material is formed into a plate material by rolling or the like, formed into a cylindrical shape, the end portion is formed into a ring shape by welding, and then fitted into a steel inner drum by a method such as shrink-fitting. The surface of the titanium plate material is finished by performing grinding and polishing. Therefore, the surface shape after polishing of the titanium material is printed on the electrolytic deposition foil.

In order to improve the surface properties of the electrolytic metal foil, there has been proposed a method of improving the surface properties of a titanium material after polishing. For example, (1) forming a titanium plate obtained by hot rolling into an arc shape, joining the butted portions by welding to form a ring-shaped intermediate product, then applying a reduction again in the cold, followed by annealing. Fine crystal grains (less than 25μm)
There is a method of producing a titanium electrodeposition drum (see Japanese Patent Application Laid-Open No. 6-93401) in which a step formed on the surface of a titanium drum is eliminated by producing a titanium electrode to improve the quality of an electrolytic foil.

[0006] The above method can eliminate surface defects due to steps of adjacent crystal grains, but may cause uneven polishing called a chirimen pattern by polishing.
Further, when a ring-shaped material is formed by cold working, the shape becomes unstable, and it becomes difficult to perform a post-process shrink fit or the like. As a method to solve this, the applicant has
A method for producing a titanium material for an electrodeposition drum shown in (2) and a titanium material for an electrodeposition drum shown in (3) were proposed.

(2) A quenching process for passing the β transformation point at a cooling rate of 1000 ° C./h or more in the cooling process of the ingot, hot rolling or annular rolling, and forming or heat treatment performed after the cooling process In a temperature range lower than the β transformation point to produce a titanium ring for an electrodeposition drum that does not produce a chirimen pattern (see JP-A-9-20971).

(3) When the thickness is 4 to 30 mm and the surface is polished to an average roughness (Ra) of 0.3 μm or less, “at a position of 10 or more points at a pitch of 0.3 to 1 mm in any direction of the surface” The difference between the maximum and minimum values of the "Vickers hardness measured value under a load of 1 kg (test force: about 9.8 N) or less" is 10 or less (see Japanese Patent Application Laid-Open No. 9-20990). .

This titanium material is subjected to β transformation at a cooling rate of 1000 ° C./h or more at the time of cooling the ingot, after hot rolling or after annular rolling, in the step of producing a plate-shaped or ring-shaped titanium material from the casting of the ingot. It can be manufactured by a manufacturing method in which a cooling treatment for passing through a point is performed, and a forming process or a heat treatment after this process is performed in a temperature range lower than the β transformation point (that is, the method described in (2) above).

[0010]

The titanium material of the above (3) produced by the method of the above (2) has good surface properties when the surface layer of the plate thickness is polished, but the electrolysis is repeated. Re-polishing to the inside may deteriorate the surface properties.

An object of the present invention is to provide a titanium plate material having a uniform polished surface even when the electrolytic drum is re-polished many times, and a method for producing the same.

[0012]

The inventor of the present invention has found that when the titanium material (3) manufactured by the method (2) is polished to the inside of the plate thickness, the surface properties of the polished surface deteriorate. The cause was investigated including the elucidation of the polishing mechanism.

Titanium is a dense hexagonal crystal (HC
It has the crystal structure of P). In general, since titanium does not have a slip component in the direction parallel to the C-axis of the HCP crystal structure during deformation, deformation in this direction is suppressed, and twinning with higher deformation resistance is required. Become.

On the other hand, in the polishing process, if the polishing resistance slightly changes depending on the location, a so-called chattering phenomenon occurs in the polishing process, and a smooth polished surface cannot be obtained. In this case, if the crystal grain size is large, twins are likely to be generated in the polishing process, and as a result, chatter phenomenon is easily induced. In particular, it was found that when crystal grains exceeding 100 μm were mixed, twins were densely generated in the crystal grains, and the polishing resistance was significantly increased locally.

[0015] The titanium plate is manufactured by hot rolling. When the titanium plate is gradually cooled after the hot rolling, static recrystallization occurs and the crystal grains become coarse. In this recrystallization process, there is a preferred orientation of recrystallization, and a crystal grain having a specific orientation grows while eroding a crystal grain having another orientation. As a result, remarkable non-uniformity in the size of the crystal grains occurs, and particularly, the polishing resistance is increased in the crystal grains having a large grain size, so that the chatter phenomenon is easily induced. To avoid this, the final temperature during rolling (finish rolling temperature) is kept within a certain range,
It is necessary to control the progress of static recrystallization by controlling the cooling rate after rolling. In addition, if the holding time is increased in the annealing treatment, the crystal grains grow, so it is necessary to control the temperature and time of the heat treatment.

The surface properties of the titanium material after polishing are such that the titanium is chemically active, and if the hardness of the material is low, a polished surface is formed, and the polished surface is pressed against the titanium surface. Investigation of the polishing mechanism revealed that no surface properties could be obtained. In order to increase the hardness of the titanium material, it is effective to increase the oxygen content.

The present invention has been completed based on the findings based on the above-mentioned investigations. The gist of the present invention is to produce a hot-rolled titanium sheet for a surface member of an electrolytic deposition drum shown in (1) below and a hot-rolled titanium sheet shown in (2) below. In the way.

(1) A titanium plate containing 0.015 to 0.120% by mass of oxygen and having no crystal grains exceeding 100 μm in the entire cross section of the thickness.

(2) Rolling a titanium ingot containing 0.015 to 0.120 mass% of oxygen at a finish hot rolling end temperature of 200 to 750 ° C., and a cooling rate of 10 ° C. /
A method for producing a hot-rolled titanium sheet, which is subjected to a heat treatment in a temperature range of 550 to 700 after cooling at a temperature of 550 min or more for a holding time satisfying the following formula. 1.2 ≦ T / t ≦ 15 where t is the thickness of the titanium material (mm) and T is the retention time (mi)
n).

[0020]

BEST MODE FOR CARRYING OUT THE INVENTION The titanium plate material for an electrolytic drum of the present invention is a titanium plate material having an oxygen content of 0.015 to 0.120% by mass and having no crystal grains exceeding 100 μm in the entire cross section of the wall thickness. is there. Note that ordinary impurities may be contained in addition to the above oxygen.

The reason why the maximum values of the chemical composition and the crystal grain size are defined in the titanium sheet material of the present invention will be described. Less than,
% Representing the component composition means mass%.

The amount of oxygen contained in the titanium material changes the hardness of the material, as will be apparent from (Example 4) described later, and affects the quality of the surface properties due to polishing. Oxygen content is 0.01
If it is less than 5%, the titanium material is soft and easily burns in during polishing. For this reason, the surface after polishing is in a state where the skin is lumpy and the polishing powder is pressed. On the other hand, when the oxygen content exceeds 0.120%, the titanium material becomes hard, and the bending workability at the time of manufacturing the drum decreases. Therefore, the oxygen content was set to 0.015 to 0.120%. Note that a desirable upper limit is 0.10%.

The impurities which may be contained in the titanium plate of the present invention are the following elements.

Fe (iron) is an element mixed in the raw material sponge titanium. If the Fe content exceeds 0.09%, the corrosion resistance decreases. Therefore, the content of Fe is desirably 0.09% or less.

Ni (nickel) is an element mixed in the raw material titanium sponge. If the Ni content exceeds 0.05%, the corrosion resistance decreases. Therefore, the content of Ni is 0.05
% Is desirable. Cr (chromium) is an element mixed into the raw material sponge titanium. Cr content
If it exceeds 0.05%, the corrosion resistance decreases. Therefore, the content of Cr is desirably 0.05% or less.

N (nitrogen) is an element mixed in titanium sponge or mixed in the dissolving step. When the content of N exceeds 0.02%, N is locally concentrated, so that a locally high-hardness region is formed and the surface properties due to polishing deteriorate. Therefore, the content of N is desirably 0.02% or less.

H (hydrogen) is an element mixed in the titanium sponge or mixed in the dissolving step or the annealing step. If the H content exceeds 0.015%, hydrogen embrittlement occurs. Therefore, the content of H is desirably 0.015% or less.

C (carbon) is an element mixed in the raw material sponge titanium. If the content of C exceeds 0.01%, the workability is reduced. Therefore, the content of C is desirably 0.01% or less.

Next, the reason why the maximum value of the crystal grain size is set to 100 μm or less will be described. Due to the action of the compressive force in the polishing process, twinning deformation occurs densely in large crystal grains having a crystal grain size exceeding 100 μm. In particular, when crystal grains exceeding 100 μm are present together with fine crystal grains of 50 μm or less, twin deformation is unlikely to occur in fine crystal grains.
In crystal grains exceeding μm, twinning deformation occurs densely, so that deformation resistance locally changes. As a result, the vibrating phenomenon is caused, and a good polished surface cannot be obtained.

Next, the reason for defining the manufacturing conditions of the titanium plate of the present invention will be described.

The final temperature during hot rolling of the titanium material and the subsequent cooling rate affect the size of the crystal grains, as is apparent from the results of Example 1 described later.

If the end temperature of the hot rolling is less than 200 ° C., strain energy is accumulated in the rolled material, and this is released at once by annealing, so that abnormal grain growth occurs in specific crystal grains,
In particular, a mixed particle state in which crystal grains exceeding 100 μm exist. As a result, the surface properties due to polishing decrease. on the other hand,
If the end temperature of hot rolling exceeds 750 ° C., coarse crystal grains are generated at the center of the wall thickness in the cooling process after rolling, so that the surface properties due to polishing deteriorate. Therefore, the end temperature of the hot rolling was set to 200 ° C. or more and 750 ° C. or less. The desired hot rolling end temperature is in the range of 300 ° C to 650 ° C. Here, the end temperature of hot rolling means the surface temperature of the rolled material.

The effect of the cooling rate of the rolled material after hot rolling is as follows:
As is apparent from Example 2 described later, it is necessary to secure a cooling rate of 10 ° C./min or more in order to prevent the generation of coarse crystal grains exceeding 100 μm.

If the cooling rate of the rolled material after hot rolling is less than 10 ° C./min at the center of the sheet thickness, static recrystallization proceeds during the cooling process. Grains are formed. When coarse crystal grains are formed after the finish rolling, they do not disappear even by annealing heat treatment, so that when polishing the central part of the thickness of the titanium sheet material, the surface properties are reduced. The upper limit of the cooling rate is not particularly limited.

Next, in the annealing process, a third embodiment described later will be described.
As is clear from the above, it is necessary to set the holding time in relation to the annealing temperature and the sheet thickness.

If the annealing temperature is lower than 550 ° C., recrystallization does not proceed. As a result, a processed structure generated by hot rolling remains in the titanium material. If the processed structure remains, the polishing processing pressure increases during polishing, so it is easy to cause wrinkles,
Good products cannot be obtained. On the other hand, when the temperature exceeds 700 ° C., the coarsening of the crystal grains remarkably progresses, and the surface properties due to polishing decrease.

The holding time in the annealing process must be determined in relation to the thickness of the titanium material. That is, when the holding time T (min) is less than 1.2 × t in relation to the plate thickness t (mm), the holding time is insufficient, and the titanium material is not uniformly heated to the center in the thickness direction. . For this reason, a hot-rolled structure remains at the center in the thickness direction of the titanium material. If the holding time T exceeds 15 × t, the holding time becomes longer, and the surface properties due to polishing deteriorate due to oxidation on the surface or coarsening of crystal grains. Therefore, it is desirable that the holding time in the annealing process satisfies the following expression in relation to the sheet thickness. 1.2 ≦ T / t ≦ 15 where t is the thickness of the titanium material (mm) and T is the retention time (mi)
n). Note that a desirable range of the holding time is 1.2
≦ T / t ≦ 10.

[0038]

EXAMPLES (Example 1) The influence of the rolling end temperature was investigated. As the material, JIS Class 1 pure titanium having the chemical components shown in Table 1 was used. Cut out a 1m long material from a 1m diameter ingot and heat it to 950 ° C.
mm. After further heating to 850 ° C, width 500mm,
Forged to a thickness of 80 mm. From this material, thickness 80mm, width 20
A rolling material having a length of 0 mm and a length of 100 mm was cut out and rolled to a thickness of 10 mm. In the rolling, the material was heated at 850 ° C., rolled to a thickness of 20 mm, waited until the final temperature shown in Table 2 was completed, and finished to a thickness of 10 mm in two passes. The termination temperature was controlled by a contact thermocouple. After rolling, the sample was left in front of the blower to increase the cooling rate. When a thermocouple is installed at the center of the thickness of the test material of the same shape as the rolled material and cooled under the same conditions after heating to 700 ° C, the average cooling rate from 650 ° C to room temperature is 1
It was 5 ° C / min. This rolled material was annealed at 650 ° C. for 30 minutes.

[0039]

[Table 1]

[0040]

[Table 2]

Hereinafter, the evaluation method will be described.

As for the microstructure after hot rolling, the microstructure was observed in a longitudinal section of the rolled material. At this time, observations were made at a position 1 mm from the surface (this is referred to as “surface portion”) and at the center in the thickness direction (5 mm from the surface, this is referred to as “center”). In this microstructure observation, the size of the crystal grains was observed at a magnification of 100 times.
Those observed in the visual field were regarded as coarse grains, and the evaluation column in Table 2 was indicated by x.

The surface properties after polishing were evaluated by cutting a test material 100 mm on a side at a position of 1 mm and 5 mm in the thickness direction from the surface with a shaper (shaping machine), and then performing PVA polishing (polyvinyl alcohol, 1000 No.) and finished polishing. At this time, those in which a pattern was observed on the surface of the test material within a 100 mm square were regarded as poor polishing properties, and the evaluation column of Table 2 was evaluated as x. Table 2
As is evident from the results, the hot rolling end temperature was 200
Test materials 1 to 4 in the range of 745745 ° C. do not exceed 100 μm in the surface layer and the central part of the crystal grains,
No pattern was observed on any surface in the polishing test.

On the other hand, the test material 5 has a rolling end temperature of 7
Since the temperature is 80 ° C., as a result of the growth of crystal grains during the cooling process, crystal grains exceeding 100 μm are generated at the center,
Polishability is also poor.

Further, since the end temperature of rolling of the test material 6 was 150 ° C., coarse crystal grains were observed in the surface layer portion, and the polishing property was poor. This is because the strain energy accumulated at the time of rolling is released during the annealing treatment, and the crystal grains having a specific orientation grow preferentially, so that they become elongated grains. (Example 2) Here, the influence of the cooling rate after rolling was investigated.

The production of the raw material was the same as in Example 1 up to the hot rolling stage, except that the final rolling thickness was 15 mm, and after rolling, it was quenched in ice water. The surface temperature of the material before quenching was 650 ° C.

A test material having a diameter of 10 mm and a length of 12 mm was sampled from the obtained material. The test piece was sampled so that the longitudinal direction was parallel to the thickness direction of the material. After heating the test material to 650 ° C. for 5 minutes by high frequency heating, it was cooled to room temperature at various cooling rates shown in Table 3, and further heated at 650 ° C. for 3 minutes.
Heat treated for 0 minutes. Embed a thermocouple in the center of the test piece,
This controlled the cooling rate. The cooling rate in Table 3 is 65
The cooling rate from 0 ° C to room temperature.

[0048]

[Table 3]

With respect to the test material after the heat treatment, the microstructure at the center in the length direction (the center of the thickness of the rolled material) was examined for the rolled longitudinal section. In order to investigate reproducibility, three test pieces were examined under the same cooling rate conditions. In this investigation, the evaluation column of Table 3 was evaluated as x when at least one crystal grain size exceeding 100 μm was observed.

As is evident from the results shown in Table 3, in the test materials 7 to 9 in which the cooling rate was 10 to 25 ° C./min, those having a crystal grain size exceeding 100 μm were not observed. On the other hand, test materials 10 and 11 whose cooling rate was slower than 10 ° C./min
As for, those having a crystal grain size exceeding 100 μm were observed. Example 3 Here, the influence of heat treatment conditions on annealing was investigated.

The production of the test material is the same as in Example 1,
A rolled material having a thickness of 10 mm was manufactured. Table 2 shows the rolling conditions for the material.
Test No. 2 (rolling end temperature is 650 ° C., cooling rate after rolling is 15 ° C./min). This rolled material was subjected to a heat treatment (annealing treatment) under the conditions shown in Table 4, and the abrasiveness and microstructure were investigated. As a comparison, a rolled material having a thickness of 10 mm was prepared by machining (cutting) to a thickness of 8 mm by one-side cutting. The method for investigating the microstructure and the polishing property is the same as the method of Example 1.

[0052]

[Table 4]

In this investigation, when a crystal grain size exceeding 100 μm was observed and when the polishing property was poor, the evaluation column of Table 4 was evaluated as x. Evaluation criteria are
This is the same as the first embodiment.

From the results shown in Table 4, the plate materials (Nos. 12 to 19) heat-treated under the conditions of the present invention did not show crystal grains of 100 μm or more, and had good polishing properties.

On the other hand, in the sheet material of No. 20, since the annealing temperature was as low as 500 ° C., crystal grains of 100 μm or more were recognized.
Poor polishability.

Since the plate No. 21 has a high annealing temperature of 800 ° C., crystal grains of 100 μm or more are recognized in the surface layer portion of the plate, and the abrasion is poor.

The plate material of No. 22 has a holding time T of 10 during annealing.
And the ratio T / t between the holding time T and the plate thickness t is 1.0, and the hot work structure remains in the center of the thickness, so that the polishing property is poor.

The plate No. 23 has a holding time T of 200 during annealing.
And the ratio T / t between the holding time T and the plate thickness t is 20.0, so that crystal grains of 100 μm or more are recognized in the surface layer of the plate material, and the polishing property is poor.

For the sheet No. 24, the holding time T during annealing is 8 minutes, and the ratio T / t of the holding time T to the sheet thickness t is 1.0,
Since the hot-worked structure remains in the center of the thickness, the polishing property is poor.

The plate No. 25 has a holding time T of 150 during annealing.
And the ratio T / t of the holding time T to the plate thickness t is 18.8, so that crystal grains of 100 μm or more are recognized in the surface layer portion of the plate material, and the polishing property is poor. (Example 4) Here, the influence of the amount of oxygen was investigated.

A 10 kg ingot (150 mm in diameter, 15 mm in length) was prepared by the VAR melting method so that the pure titanium material had the oxygen content shown in Table 5.
0mm). After heating this ingot to 950 ° C, width 10
It was forged into a square bar having a thickness of 0 mm and a thickness of 50 mm. Then, it was heated to 850 ° C. and rolled to a thickness of 10 mm. End temperature during rolling is 650
° C. After rolling, heat treatment was performed at 600 ° C. for 30 minutes.

[0062]

[Table 5]

A test material having a side of 100 mm was sampled from the material after the heat treatment, and the polishing property was examined. The investigation method is the same as in the first embodiment. Among these, the evaluation of Table 5 was evaluated as x for the materials judged to have poor polishing properties. The hardness of the test material was measured using a Vickers hardness tester at a load of 1 kg (test force 9.8 N).
Measurements were made at various locations.

In Test Nos. 26 to 29 of the invention examples, the Vickers hardness is in the range of 131 to 195, and the surface properties and bending workability when polished are good. On the other hand, the test material of Test No. 30 of the comparative example had a low oxygen content of 0.012% by mass, and thus had poor surface properties when polished. Also, the test number
The 31 test materials had a high oxygen content of 0.135% by mass.
Vickers hardness is 210 and bending workability is poor.

[0065]

According to the titanium material of the present invention, the oxygen content and the size of crystal grains are adjusted, so that the polishing material is excellent in abrasiveness and a smooth surface can be obtained. If this is used for the surface member of the electrolytic deposition drum, it becomes possible to produce an electrolytic metal foil having a smooth surface.
The hot rolled titanium sheet can be manufactured at low cost by defining the rolling end temperature, the cooling rate after rolling, and the heat treatment conditions after cooling.

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Claims (2)

[Claims] 1. A titanium plate containing oxygen in an amount of not less than 0.015% by mass and not more than 0.12% by mass.
A hot-rolled titanium sheet for a surface member of an electrolytic deposition drum, characterized in that no crystal grains exceeding 0 μm are present. 2. The end temperature in hot rolling of a titanium material containing oxygen in an amount of 0.015% by mass or more and 0.12% by mass or less.
Roll at 200 ° C or higher and 750 ° C or lower.
A method for producing a hot-rolled titanium sheet, comprising: cooling at a cooling rate of not less than min and maintaining a temperature in a range of not less than 550 ° C. and not more than 700 ° C. according to the following formula. 1.2 ≦ T / t ≦ 15 where t is the thickness of the titanium material (mm) and T is the holding time (mi)
n).