JPH06101066A - Plated steel sheet for di can excellent in workability and rusting resistance and its production - Google Patents

Abstract

PURPOSE:To produce a DI can capable of high speed can making, furthermore finished with low forming energy and, moreover, excellent in rusting resistance on the outer face of the can, particularly, on the can bottom. CONSTITUTION:This is a steel sheet 4 contg., by weight, 0.5 to 3.5% Sol.Al, and in which, on the surface, Al2O3 grains having 0.01 to 15mum grain size are formed by 1X10 to 1X-10<6> pieces/m<2>. At least one side of the steel sheet 4 is coated with tin 2 by 1.0 to 5.6g/m<2>, and on its upper layer, a chemical conversion film 3 is formed.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a tin-plated steel sheet for DI cans which is subjected to drawing and ironing, and a method for producing the same, and is particularly intended to improve the workability and rust resistance of the steel sheet.

[0002]

2. Description of the Related Art DI cans (Drawn and Ironed cans), which are mainly used as beverage containers, are punched into a circular shape (Drawn) in the first step of processing and then formed into a cup shape, and then another step. Redrawn into a small cup
At the same time, it is passed through an ironing die and is ironed between the outer die and the inner punch, and the length of the body is increased while reducing the plate thickness of the side wall of the body part (Ironing). Molded into cans and manufactured.

The two-piece can produced by DI molding as described above has a weak body wall due to the thin wall of the can wall and cannot be used in a vacuum can for vacuum tightening. It is mainly used as a can for beverages that generate positive pressure, and on the contrary, the plate thickness of the can wall is thin, so compared to the case where the can bottom and the can wall are manufactured with the same plate thickness. There is a merit that the amount of materials used can be reduced, and there is high demand because it is advantageous in terms of cost, and it is expected that its applications will be expanded in the future. In particular, tin plate (tin plated steel sheet) used as a material for DI cans is cheaper than aluminum materials,
The demand growth is desired.

[0004]

In the molding of this DI can, a high degree of workability is required because of the severe processing as described above, and in recent years, high speed processing has been performed to improve the productivity of the DI molding processing. As materials are being pursued, there is a demand for materials with better moldability than at present. In the case of the tin-plated steel sheet described above, Sn plays a role of a lubricant at the time of ironing while ensuring the corrosion resistance, and is suitable as a steel sheet for DI can.

However, although the tin-plated steel sheet can be subjected to high-speed DI forming to some extent, when high-speed can-making is performed, the plated tin is melted by heat generated during the forming and the can is seized on the die, or partially. As a result of the conventional tin melting, the gloss of the wall of the can becomes uneven, which becomes a defect that impairs the beautiful appearance, and there is a problem that the can-making speed cannot be increased as expected.

In order to solve this problem, for example, Sn
It is also conceivable that a metal film having a melting point higher than (melting point of about 232 ° C) is attached by plating or an adhesive to increase the can making speed until just before the temperature of the can reaches the melting point. In JP-A-1-132778, Sn such as Zn, Ni and Ti is used.
It is disclosed that a metal having a higher melting point than that is plated, and then Al is plated to manufacture a DI can material.
However, the hardness of the coating of Zn, Ni, Ti, etc. is much harder than that of soft Sn, and the forming energy is excessively required as compared with the case of tin-plated steel sheet, which is not economical.

On the other hand, this plating film is not simply made soft. Since the bottom of the can may be rubbed during transport and the coating may be scratched, and the iron material may be exposed to produce tin, so if the coating is soft, a protective coating film must be carefully applied.

As described above, in the conventional galvanized steel sheet for DI cans, when high-speed can manufacturing, the temperature of the can body is increased by frictional heat, and the tin is melted to cause uneven gloss defects. Therefore, the development of a material for DI cans, which prevents the occurrence of uneven gloss defects on the outer surface of the cans due to melting of tin and enables high-speed can manufacturing, has been an important issue. In addition, it is desired that the cans can be formed with a lower forming energy than that of the conventional tin-plated steel sheet.

The present invention was devised in view of the above problems of the prior art. It enables high-speed can manufacturing, requires low molding energy, and is excellent in rust resistance on the outer surface of the can, especially the can bottom.
A plated steel sheet for producing an I can and a method for producing the same are provided.

[0010]

Therefore, the DI can-plated steel sheet of the present invention contains Sol.Al: 0.5 to 3.5 wt%, and the surface thereof contains Al ₂ O ₃ particles having a particle size of 0.01 μm or more and 15 μm or less. × 10 ²
~ 1 x 10 ⁶ pieces / m ² produced, wherein at least one side of the steel sheet is coated with tin in an amount of 1.0 g / m ² or more and 5.6 g / m ² or less, and a chemical conversion coating is formed on the upper layer thereof. The basic feature is that it is formed.

The method for producing a plated steel sheet for a DI can of the second invention is a steel sheet containing Sol.Al: 0.5 to 3.5 wt% in an atmosphere having an oxygen partial pressure of 10 ^-6 atm or more and 10 ^-2 atm or less. By heat-treating at a temperature of 500 ° C. or higher and 900 ° C. or lower, 1 × 10 ² of Al ₂ O ₃ particles having a grain size of 0.01 μm or more and 15 μm or less is formed on the surface of the steel sheet.
〜1 × 10 ⁶ pieces / m ^{2 and} at least one side of which is plated with 1.0g / m ² or more and 5.6g / m ² or less tin, then electrolytic chromic acid treatment, immersion chromic acid treatment, phosphate treatment It is characterized by performing any one of the chemical conversion treatment of.

The structure of the present invention will be described in detail below.

As shown in FIG. 1, the surface of the cold-rolled steel sheet 4 has A
l ₂ O ₃ particles 1 are formed, and metallic tin 2 is plated between the particles 1 and the particles 1 or on the Al ₂ O ₃ particles 1. On the metal tin 2, a chromium oxide film or a phosphoric acid treatment film is applied as the chemical conversion treatment film 3.

In the above constitution, the particle size, density, tin plating amount, etc. of Al ₂ O ₃ particles 1 are peculiar to the present invention, and in the second invention, the particle size of Al ₂ O ₃ particles 1 and The specific manufacturing method is limited to adjust the density.

The particle size above Al ₂ O ₃ particles 1 of Al ₂ O ₃ particles 1 is adjusted to 15μm particle size of less than or 0.01 [mu] m. If the particle size is less than 0.01 μm, the alloying reaction between iron and tin due to heat generation during DI molding cannot be suppressed.
On the other hand, if the particle size exceeds 15 μm, the alloying reaction between iron and tin can be suppressed, but galling will occur during DI molding, and the tool will be easily damaged.

[0016] Al ₂ Density of O ₃ Density The Al ₂ O ₃ particles 1 of particles 1 and ² per 1 × 10 ² ~1 × 10 ⁶ cells 1 m. If this density is ² per 1 × 10 than ^two 1 m, can not be suppressed alloying reaction of iron and tin due to heat generation during DI molding, and iron land is exposed rubbing can bottom during transport Easily occurs and the rust resistance is inferior. On the other hand, if the density exceeds 1 × 10 ⁶ , the alloying suppression effect and rust resistance will not be a problem, but the adhesion of the tin plating layer to the base iron will be poor, and D
When I is processed, tin peels off and the appearance deteriorates.

Al for adjusting to the above particle size and density
₂ O ₃ formation method Al ₂ O ₃ particles 1 particle 1 is affected the product degree by the oxygen partial pressure and ambient temperature in the Al concentration and the atmosphere in the steel. Al ₂ O ₃ particles 1 having the above-mentioned particle size and density are steel sheets having a composition of Sol.Al 0.5 to 3.5% and finally 500 ° C in an atmosphere of oxygen partial pressure of 10 ^-6 atmospheres or more and 10 ^-2 atmospheres or less. It is formed by performing heat treatment at a temperature not lower than 900 ° C. and not higher than 900 ° C. That is, in order to form Al ₂ O ₃ particles 1 having the above grain size, the amount of Sol.Al in steel must be 0.5% or more, and if it exceeds 3.5%, the grain size becomes excessively large. , Galling is likely to occur during DI molding. Furthermore,
If the oxygen partial pressure in the atmosphere during the heat treatment is less than 10 ^-6 atmospheres
The formation of Al ₂ O ₃ particles 1 is difficult, and the oxidation reaction of aluminum is likely to proceed only when the Al ₂ O ₃ particles 1 are more than that, and when the partial pressure exceeds 10 ^-2 atm, only the reaction between oxygen and aluminum occurs. However, the steel is easily oxidized to produce iron oxide, and excessive generation of iron oxide causes blueing, which makes it difficult to remove even by pretreatment before tin plating.
Therefore, plating failure is likely to occur. On the other hand, when the ambient temperature is less than 500 ° C, Al ₂
This is because it becomes difficult to generate the O ₃ particles 1, and conversely, when the temperature exceeds 900 ° C., the particle size of the particles 1 becomes excessively large, and galling is likely to occur during DI molding. The heat treatment as described above can be performed in a continuous bright annealing line or can be performed using a box-type bright annealing furnace.

Tin Plating Amount of tin 2 is 1.0 g / m ² or more and 5.6 g / m ² or less. That is, if the tin 2 plating amount is less than 1.0 g / m ^2, DI
The molding energy during molding becomes excessively high, and 5.
If it exceeds 6 g / m ² , the amount of plating will be excessive, and the effect will be saturated in terms of the role as a lubricant during processing and ensuring of corrosion resistance. There is no particular limitation on the plating method, and electroplating using a normal ferrostane bath, halogen bath, alkali bath or the like may be used.

Chemical conversion treatment film Chemical conversion treatment film 3 formed on the above tin plating film
Is formed in order to prevent tin from being excessively oxidized and yellowing during transportation or storage of steel sheet. Specifically, the amount of chromium is 0.1 to 15 mg / m ^{2 and} the amount of chromium oxide is 0.2 to 15%. A phosphate coating of ~ 5 mg / m ² or the like is preferable (less than the lower limit of the above coating amount, the oxidation resistance is inferior, and oxidation progresses during transport and storage of steel sheet to cause yellowing. If it exceeds, it will be excessive and the effect will be saturated). Incidentally, the chemical conversion treatment method is not particularly limited, immersion treatment or electrolytic treatment in a sodium dichromate solution or chromic anhydride solution, or tin phosphate, immersion treatment in a liquid such as Na phosphate or electrolytic treatment Can be done by.

[0020]

EXAMPLES Specific examples of the present invention will be described in detail below.

The steel sheets No. 1 to No. 6 and No. 17 shown in Table 1 below were produced by carrying out the second invention method.
After degreasing a cold-pressed steel plate with a thickness of 0.255 mm containing 0.6 to 3.3% of Al in steel, No. 1 to No. 6 are 75 in the continuous annealing line.
No. 17 was manufactured by performing bright annealing heating at 0 ° C. for 30 seconds and at 620 ° C. for 30 seconds. The oxygen partial pressure of the furnace atmosphere at this time was 2 × 10 ^{−5 to} 3 × 10 ⁻³ atm. Then, after cooling to room temperature, it is wound up, and then the surface roughness Ra is about 1 by a conventional method.
It was temper-rolled to have a thickness of μm and wound into a coil. This cold rolled steel sheet after temper rolling is subjected to alkaline electrolytic degreasing and electrolytic pickling, and then usually tin plating conditions (ferrostane bath)
In performs electric tin plating on both sides, to form a tin plating film having a thickness of ^{1.5g / m 2 ~5.6g / m 2} . Finally, it was immersed in a sodium dichromate solution (20 g / l) for 1 second for chemical conversion treatment, and a CrOx film was deposited in a chromium amount of about 1 mg / m ² . The tin plating was manufactured with the same plating amount on both sides and with different plating amounts on the front and back sides.

The steel sheets No. 7 and No. 8 and No. 16 in the table are
The annealing treatment is performed in a box-type annealing furnace, and No. 7 and No. 8 are
It was manufactured by the same method as the manufacturing method of the steel sheets of No. 1 to No. 6 above, except that annealing was performed at 850 ° C. for 12 hours and No. 16 at 520 ° C. for 1 hour.

No. 9 steel sheet shown as a comparative example in the table is
It was produced under the same conditions as the steel sheets No. 1 to No. 6 except that the Al content in the steel was 4.2%, which was outside the scope of the present invention in that respect.

Similarly, the steel sheet of No. 10 of the comparative example in the table has the oxygen partial pressure of 3 × 10 ⁻² in the annealing atmosphere, which is outside the range of the present invention in that respect. -Manufactured under the same conditions as No. 6 steel plate.

Further, the steel sheet No. 11 of the comparative example in the table is the same as the steel sheets No. 1 to No. 6 except that the annealing temperature is 910 ° C., which is outside the scope of the present invention in that respect. It was manufactured under the same conditions.

Further, the steel sheet No. 12 of the comparative example in the table has a tin plating amount of 0.9 g / m ^2, which is outside the scope of the present invention in that respect, except for that point. Manufactured under the same conditions as the .6 steel plate.

In addition, the steel sheet No. 13 of the comparative example in the table has an oxygen partial pressure of 2 × 10 ⁻² atm in the annealing atmosphere, and Al ₂ O ₃
It was manufactured under the same conditions as the steel sheets No. 1 to No. 6 except that the density of the particles was 2 × 10 ⁶ particles / m ^2, which was outside the scope of the present invention in that respect.

On the other hand, the steel sheets No. 14 and No. 15 shown as the conventional example were manufactured as follows. That is, the amount of Al in the steel
After degreasing the cold-rolled steel sheet containing 0.002%, bright annealing heating was performed at 750 ° C for 30 seconds in a continuous annealing line. The oxygen partial pressure in the atmosphere at this time was 3 × 10 ⁻⁶ atm. After cooling to room temperature, it is wound up, and then the surface roughness Ra is about 1 by the conventional method.
It was temper-rolled to have a thickness of μm and wound into a coil. This cold rolled steel sheet after temper rolling is subjected to alkaline electrolytic degreasing and electrolytic pickling, and then usually tin plating conditions (ferrostane bath)
Both sides were electrotinned to form a tin-plated film with a thickness of 2.8 g / m ² . After that, dip it in a sodium dichromate solution (20g / l) for 1 second to perform chemical conversion treatment,
The coating was deposited with a chromium amount of about 1 mg / m ² .

The steel sheet of Comparative Example No. 18 in the table has an annealing temperature of 4
It was produced under the same conditions as those of No. 16 (however, the amount of Al in steel was 1.5 wt%) except that the temperature was 50 ° C., which was outside the range of the present invention.

[0030]

[Table 1]

The plated steel sheet thus obtained was subjected to the following tests to evaluate the DI formability and the rust resistance of the can after forming. The results at that time are also shown in the same table.

The test material was punched into a disk shape with a diameter of 123 mm,
This is placed in a commercially available cupping press with an inner diameter of 72 mm and a height of 36 mm.
The cup was then inserted into a DI machine, and recirculation and three-stage ironing were performed at a punch speed Max of 50 m / min and a stroke length of 600 mm while circulating a coolant at 40 ° C. The molded can body has an inner diameter of 52 mm, a height of 130 mm, and a can body thickness of about 0.12 m.
It was thin to m. Each DI moldability obtained in such a manufacturing process was evaluated by calculating the molding energy required for molding from the molding load and the amount of deformation, and evaluating the magnitude of the calculated value. The lower the molding energy is, the better the moldability is. The presence or absence of gloss unevenness was evaluated by visually observing the body of the can after molding and evaluating the appearance. For rust resistance,
The molded can was washed with degreased water, dried, and then subjected to a salt spray test with the can being inverted, and the time until rust was generated in the processed portion of the can bottom was investigated and evaluated.

From the table, No. 1 to No. 1 which are examples of the present invention.
When DI cans are manufactured using No. 8, No. 16 and No. 17 steel plates as raw materials, Al ₂ O ₃ particles are generated with an appropriate particle size and density on the surface of the steel plate before plating, and DI cans are produced at high speed. However, even if the uneven gloss does not occur, the molding energy is low, and the rust resistance of the can bottom is good.

On the other hand, as in the case of the comparative example No. 9 steel sheet,
If the amount of Al is too large, the particle size of the Al ₂ O ₃ particles becomes too large, causing galling and increasing the molding energy. Further, since the oxygen partial pressure in the annealing atmosphere of the No. 10 steel plate was outside the range of the present invention, oxidation proceeded to such an extent that bluing occurred on the surface of the steel plate, resulting in defective plating. In the No. 11 steel plate whose annealing temperature was too high, as in the case of the No. 9 steel plate, galling occurred because the grain size of Al ₂ O ₃ particles was too large, and the forming energy was also high. Since the No. 12 steel sheet had a small amount of tin plating, the forming energy was high, and the rust resistance of the can bottom was slightly inferior. Furthermore, for No. 13 steel plate, 1
Since the number of Al ₂ O ₃ particles per m ² was excessive, tin peeled off during DI molding, and it was not possible to make a can.

Further, the steel sheet No. 18 of the comparative example in the table had a low annealing temperature, so that uneven gloss was produced and the forming energy was high. Also, the rust resistance of the can bottom was inferior.

In the conventional examples of No. 14 and No. 15 steel plates, Al
_{Since no 2} O ₃ particles were generated, alloying could not be suppressed, resulting in uneven gloss and increased molding energy. In order to avoid these problems, the can manufacturing speed must be reduced, and it becomes impossible to meet the demand for high speed can manufacturing.

[0037]

According to the constitution of the present invention described in detail above, high speed can manufacturing can be performed with low molding energy, and the unevenness of gloss can be prevented from occurring on the outer surface of the DI can. Not only that, the DI cans produced have excellent rust resistance, especially in the bottom of the cans.

[Brief description of drawings]

FIG. 1 is a cross-sectional view showing a state of a tin-plated steel sheet according to the present invention.

─────────────────────────────────────────────────── ─── Continuation of the front page (51) Int.Cl. ⁵ Identification number Internal reference number FI Technical indication C25D 5/26 B 5/36 5/48 // C21D 9/48 H (72) Inventor Hiroyuki Kato 1-2-1, Marunouchi, Chiyoda-ku, Tokyo Nihon Steel Tube Co., Ltd.

Claims (2)

[Claims] 1. Sol.Al: 0.5 to 3.5 wt%, and 1 × 10 ² of Al ₂ O ₃ particles having a particle size of 0.01 μm or more and 15 μm or less on the surface thereof.
~ 1 x 10 ⁶ pieces / m ² produced, wherein at least one side of the steel sheet is coated with tin in an amount of 1.0 g / m ² or more and 5.6 g / m ² or less, and a chemical conversion coating is formed on the upper layer thereof. A plated steel sheet for DI cans that is excellent in workability and rust resistance, which is characterized by being formed. 2. A steel sheet containing Sol.Al: 0.5 to 3.5 wt% is finally placed in an atmosphere having an oxygen partial pressure of 10 ⁻⁶ atm or more and 10 ⁻² atm or less.
By heat treatment at a temperature of 500 ° C or higher and 900 ° C or lower,
1 Al ₂ O ₃ particles having a particle size of 0.01 μm or more and 15 μm or less on the surface of the steel plate
X 10 ² to 1 x 10 ⁶ pieces / m ^{2 are} formed, and at least one side thereof is plated with 1.0 g / m ² or more and 5.6 g / m ² or less tin, then electrolytic chromic acid treatment, immersion chromic acid treatment, phosphorus A method for producing a plated steel sheet for a DI can, which is excellent in workability and rust resistance, characterized by performing any one of chemical conversion treatments of acid salt treatment.