JPH01298142A - Hot dip aluminized steel sheet for vessel, production thereof and can - Google Patents

Abstract

PURPOSE:To improve the workability and corrosion resistance of a hot dip aluminized steel sheet by successively forming an Fe-Al alloy layer and an Al (alloy) film on the surface of a steel sheet and cold rolling the steel sheet at a specified rolling reduction to break the alloy layer and to bring the alloy layer and the Al film into metallic bond. CONSTITUTION:An Fe-Al alloy layer and an Al (alloy) film of >=10mum thickness are successively formed on the surface of a steel sheet. This hot dip aluminized steel sheet is cold rolled at <50% rolling reduction to partially break the Fe-Al alloy layer and to bring Fe and >=10% of the Al alloy film into metallic bond. The resulting hot dip aluminized steel sheet has superior adhesion and workability, so it is fit for drawing-ironing(DI) or drawing A can made of the steel sheet has higher corrosion resistance than a commercially available Al can.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of the Invention The present invention relates to a hot-dip aluminized steel sheet for containers having excellent workability and corrosion resistance, and a method for manufacturing can bodies and other steel sheets formed from the steel sheet.

BACKGROUND OF THE INVENTION BACKGROUND OF THE INVENTION Beverage cans for beer, carbonated beverages, etc. are made from aluminum plates or tin plated steel plates. Until the 1960s, cans were mainly made by soldering or gluing, but since the development of cans by drawing and ironing (hereinafter referred to as DI cans according to industry convention), the material used has been aluminum. They became the two most excited players. This is because manufacturing DI cans requires high processing lubricity on the outer surface of the can and excellent corrosion resistance on the inner surface of the can.

Problems to be Solved by the Invention Aluminum has excellent workability and corrosion resistance, so D
After pre-processing, it is now being used favorably for cans of beer and carbonated beverages. On the other hand, when using a steel plate as the material, it exhibits excellent smoothness in the processed parts on the outside of the can, but on the inside of the can, if the inner surface coating applied after DI forming is not completely finished, the coating film may deteriorate. There is a problem that iron elution occurs from the defective parts, resulting in a decrease in taste and flavor.

Therefore, aluminum cans are coated with one coat of can interior after DI molding, whereas tin cans require two coats of can interior coating.

However, the steel plate itself has many advantages, such as being strong, allowing the use of thinner sheets, preventing dents and scratches on the can body, being able to be conveyed by magnetic force, and being inexpensive.

Therefore, it has been desired to develop a material that has both the advantages of steel plate and the excellent content resistance properties of aluminum.

On the other hand, aluminized steel sheets have excellent heat resistance and corrosion resistance, and have traditionally been manufactured by hot-dip plating. In conventional hot-dip aluminized steel sheets, the molten aluminum reacts with the base iron to form a fairly thick alloy layer, and when exposed to severe processing, the aluminum film peels off from the two alloy layers, making the container difficult to use. The 6 alloy layer, which was not used as a material for
) has developed to a thickness that is sufficiently observable, and the iron surface is completely covered with an alloy layer.

As a method of suppressing alloy layer growth, there is a method of adding silicon to aluminum in an amount of approximately 10% to improve workability.

In addition, as a method for reducing the alloy layer formed between the steel sheet and the aluminum plating layer by pre-plating before hot-dip plating, for example, Japanese Patent Application Laid-Open No. 57-7131
The methods described in JP-A No. 78, JP-A-57-140884, JP-A-58-33483, JP-A-57-114850, JP-A-57-70288, etc. have been proposed.

However, in all of these methods, the reduction of the alloy layer is insufficient, and even if the thickness is thin, the steel surface is still completely covered with the alloy layer, so it is difficult to obtain a steel plate with good workability. It is difficult to do so, and there are no examples of it being applied to containers.

The purpose of the present invention is to eliminate the drawbacks of conventional aluminized steel sheets and provide a hot-dip aluminum-plated steel sheet for containers with excellent workability and corrosion resistance, a method for manufacturing the same, and a can body with excellent corrosion resistance manufactured using the steel sheet. It is about providing.

Means for Solving the Problems In order to achieve the above object, the present invention improves the point that the iron-aluminum alloy layer of the conventional aluminized steel sheet completely covers the surface of the steel sheet. A steel plate for cans in which a steel plate is partially fractured and a steel plate substrate and an aluminum or aluminum alloy as a plating film are directly metal bonded at the fractured part, a method for manufacturing the same, and a can manufactured using such a steel plate for cans. It provides the body. That is, the present invention has an iron-aluminum alloy layer on the surface of a 1.6Ji steel plate, an aluminum film or an aluminum alloy film on the surface, and a broken part in the iron-aluminum alloy layer, and the broken part. 2. Hot-dip aluminum plated steel sheet for containers, characterized in that iron and aluminum film or aluminum alloy film are metallically bonded by 10% or more through parts. 2. An iron-aluminum alloy layer on the surface of the thin steel sheet and an iron-aluminum alloy layer on the surface. A hot-dip galvanized steel sheet with an aluminum film or an aluminum alloy film of 10 pm or more is used, and the rolling reduction is 5.
Melting for containers characterized by cold rolling at a reduction rate of less than 0% and at which the iron-aluminum alloy layer is partially broken and the iron and aluminum film or aluminum alloy fl are metallically bonded by 10% or more. Method for manufacturing aluminum plated steel sheet, 3. A can based on a thin steel plate has an iron-aluminum alloy layer on both sides, and an aluminum film or an aluminum alloy film on the surface thereof, and the iron-aluminum alloy layer has a broken part, and the broken part is A layer consisting of a metallic bond between iron and aluminum or an aluminum alloy film, and on the inner surface of the can, a film or a phosphate film having at least the outermost layer of a chromium compound on the surface;
A can body characterized in that it has sequential paint films.

action The present invention will be explained in detail below.

The present invention uses an aluminum-based hot-dip plated steel plate as a steel plate for cans, and changes the bonding form between the base iron and the plated metal, aluminum or aluminum alloy. As mentioned above, in conventional hot-dip aluminized steel sheets, the iron base is always covered with an alloy layer, and although there are slight differences in workability depending on the thickness, DI cans are formed by intense drawing and ironing. Cannot be applied to Japan, DI
The present invention was developed as a result of various studies on the form of bonding between iron and plated metal that can withstand high-level processing of cans and the like.

The present invention secures an intermetallic bond of 10% or more between the base steel sheet and the plated metal in order to obtain processing adhesion of the plated metal. The intermetallic bond here refers to a state in which there is substantially no alloy layer at the interface between iron and plated metal,
For example, it is similar to the interface between iron and plated metal when metal is plated by electroplating.

The ratio of the above-mentioned intermetallic bond in the present invention can be determined by observing the cross section of a hot-dip aluminized steel plate under a microscope, and determining the ratio of the broken line portion (where the alloy layer is broken) to the total length of the linearly observed alloy layer portion (the total length of the observation field). It is expressed as a percentage of the total length of the

In materials where the interface between iron and plated metal is completely covered with an alloy layer, such as conventional hot-dip aluminized steel sheets, DI
During processing, especially during ironing, the alloy layer is destroyed and the aluminum plating layer peels off. In more severe cases, the aluminum plating layer may peel off during the drawing process. In the hot-dip plating method, since the formation of an alloy layer is unavoidable, it is difficult to apply it as a material for just one can without taking measures to improve adhesion.

The present invention has discovered a hot-dip aluminized steel sheet that can be used in DI processing by partially destroying the alloy layer without peeling off the plating layer and creating an intermetallic bond of 105 or more. Cold rolling is the most suitable method for destroying the alloy layer without peeling off the plating layer. In this case, excessively strong processing will deteriorate the mechanical properties of the base material, causing problems in the DI processability of the steel sheet itself. The adhesion of the plating film improves as the reduction rate during cold rolling increases, but the mechanical properties of the base material deteriorate, so an appropriate reduction rate must be set. When performing multi-pass rolling, better adhesion can be obtained by employing a high rolling reduction in the first stage.

The quantity and quality of the alloy layer formed during aluminum plating is also important. When the amount of the zero alloy layer is small (about 1 to 4 microns), it is possible to reduce the amount of iron by more than 10% at a reduction rate of about 5 to 30%. ~When a metallic bond between aluminum is obtained and the amount of alloy layer is large (4 to 1
(about 0 micron), the variation becomes large, but from 20 to
A rolling reduction rate of about 70% is required. However, rolling at a reduction rate of 50% or more is not preferred because the mechanical properties of the material deteriorate significantly, causing problems in flange formability during DI molding, etc.

As mentioned above, in order to fully exhibit the effects of the present invention,
You can expect excellent mechanical properties! ! An alloy layer with a small amount of alloy layer and a brittle and easily crushed alloy layer is preferable.

Next, regarding the thickness of the plating layer, the amount of alloy layer and the ratio of unalloyed aluminum or aluminum alloy are relatively important factors. On the other hand, unalloyed aluminum or aluminum alloy needs to exist in an amount of 10 Bm or more. This is because, although the plating density is improved by increasing the amount of metal bonding, the presence of a soft metal layer is important in order to alleviate the presence of a hard alloy layer. D.I.
In order to prevent scratches on the outer surface of the can during processing, it is necessary to have at least twice as much unalloyed aluminum or aluminum alloy as the alloy layer.Aluminum alloy in the present invention refers to silicon, manganese, An alloy made by blending magnesium, iron, etc. with aluminum.

Aluminum-based hot-dipped steel sheets with a metal bond of 10% or more manufactured by this method have excellent plating adhesion and workability, so they are suitable for DI processing or drawing processing, and cans that are manufactured by this process. provides excellent corrosion resistance comparable to commercially available aluminum cans.

In the case of DI cans, after DI processing, the cans are degreased, a film containing a chromium compound is formed on at least the outermost layer by chromate treatment, or a phosphate film is formed, and then the inner surface is painted and the outer surface is printed. In the case of the steel plate of the present invention, since the surface of the can body after processing is completely coated with aluminum or aluminum alloy, painting can be completed in one time, similar to aluminization. Corrosion resistance is equivalent to that of aluminum, and by utilizing the strength of steel and using a pure aluminum film with good corrosion resistance, it is possible to obtain corrosion resistance that is superior to commercially available aluminum.

This is because, in the case of commercially available aluminum, in order to increase the strength of the can,
This is because the situation necessitates the use of alloyed aluminum tips even at the expense of corrosion resistance.The cans manufactured using the steel sheet of the present invention have the good corrosion resistance of aluminum.

Due to sacrificial corrosion protection against iron, iron does not dissolve into the contents of beer and carbonated beverages, and the taste and flavor do not deteriorate, resulting in extremely superior corrosion resistance compared to tin cans. I can do it.

In addition, in the case of DRD cans (cans formed by drawing 2 to 3 times), the steel plate for cans is subjected to surface conditioning such as degreasing and pickling, followed by treatment to form a film containing a chromium compound on at least the outermost layer, and phosphate treatment. After applying surface treatment and painting, it is drawn into a can body. In this case as well, extremely excellent corrosion resistance can be obtained as in the case of the DI can.

According to the findings of the present inventors, an example of forming a film having a chromium compound at least on the outermost layer is cathodic electrolysis in a chromic acid solution containing some anions. By performing a treatment, a film having a two-layer structure of metallic chromium and a hydrated chromium oxide film is formed by electrolysis, or by cathodic electrolysis treatment in a solution of a chromic acid compound, water-reducing chromium oxide is the main component. Methods such as forming a film by electrolysis were effective.

At this time, chrome skin [closed, converted to chrome, 5 + *
If it is less than 50 mg/rn', the effect on processing adhesion and paint corrosion resistance of the organic coating will be weak, and if it exceeds 50 mg/rn', the effectiveness will be saturated and coloration will occur due to the chromium film, which is undesirable. Particularly desirable amounts of chromium film are as follows: 15
~30I1g/rrr'te.

The method of forming a chromium compound film is not limited to the electrolytic method, but chromium compound films formed by chemical reactions can also provide sufficient performance. By forming a chromium phosphate film of 5 to 50+wg/m' in a treatment solution containing the main components, it is possible to obtain extremely excellent processing adhesion and paint corrosion resistance of an organic coating film.

The can body thus obtained has on both sides a thin steel plate as a base material, an iron-aluminum alloy layer partially having the above-mentioned metal joints on the surface, and an aluminum film or an aluminum alloy film on the surface. The inner surface of the can further comprises a film having a chromium compound or a phosphate film on the outermost layer, and a paint film coated on the surface thereof. On the other hand, the outer surface of the can differs depending on the purpose, and can products are produced by printing or painting on the surface of the aluminum film or aluminum alloy film as it is, or with a surface treatment film interposed therebetween.

Example 1 A cold-rolled thin steel plate having a thickness of 0.35 mm was passed through a continuous hot-dip aluminum plating line to perform hot-dip aluminum plating containing 10% silicon. At that time, the thickness of the alloy layer was 1.5 microns, and the thickness of the Kinku aluminum plating was 2 microns.
Adjusted to 0 microns. After plating, total plate thickness 0.311
+u+ steel plates are rolled at 30% in a two-stand cold rolling mill.
0.27 at rolling reduction rate (20% in 1st stage, 10% in 2nd stage)
It was rolled to 3mm. When the cross section of this steel plate was observed with an optical microscope, the ratio of the portion where the alloy layer was destroyed and metal bonding between iron and aluminum had occurred was about 35%.

A steel plate with an aluminum film of approximately 15 microns after rolling was drawn twice from a blank diameter of 139 mm to an inner diameter of 85 mm.
It was molded into a mm cup. After that, one can is approximately 130cm tall after 3 stages of ironing! It was used for molding. The thinnest part of the final product is 0.
The length of the intestine was 085 mm, and the thickness of the flange portion after trimming was O, +50 mm.

After the DI molding, the cans were degreased and treated with phosphoric acid, the outside was printed, the inside was painted, and the can was molded into a φ flange. As for the neck-in processing, the triple neck-in method is used to make the external shape after the lid is rolled up.
was formed to become.

During this series of forming steps, the hot-dip aluminum plating film withstood the forming without peeling off at all, and the final product had perfect coverage of the iron.

The inner surface of each can was spray-painted with 40 epoxy paints, and after baking, the cans were filled with beer and the amount of M and Fe eluted was measured after 6 months at room temperature. , 0.14 ppm M elution was analyzed, but Fe
Below the analytical detection limit (< 0.01ppm)
It was confirmed that this material has extremely excellent corrosion resistance in practical terms.

Example 2 A cold-rolled steel plate having a thickness of 0.43 mm was plated with pure aluminum containing a small amount of impurities to a thickness of 70 microns (both sides total) in a hot-dip aluminum plating line. In this case, the average thickness of the alloy layer formed was about 4.7 microns per side.

A steel plate with a plate thickness of 0.50++n after plating is 45-
Rolled to a plate thickness of 0.273mm at a reduction rate of 496D
It was subjected to I molding. When the cross section of this steel plate was observed with an optical microscope, the ratio of the portion where the alloy layer was destroyed and metal bonding between iron and aluminum had occurred was approximately 75%.

DI molding was carried out under the same conditions as in Example 1, and the adhesion of the hot-dip aluminum plating film on the can surface after degreasing, cleaning, and phosphate treatment was determined by a tape peeling test, but no peeling was observed. The sushi was of good quality.

The inner surface of the can body was spray-coated with 65 mmg of epoxy paint per can, and after baking, an actual can test was conducted using a commercially available cola drink as the content. When we measured the elution amount of M and Fe after 12 months at room temperature, we detected 4.3 ppm of M elution and 0.3 ppm of Fe elution, but there was no particularly noticeable corrosion on the inner surface of the can, and the taste was poor. Both flavors were at a good level with no problems.

Example 3 A steel plate with a thickness of 0.255 m was plated with pure aluminum to a total thickness of 30 microns on both sides. Alloy layer thickness is 3.5 mm
micron, and the plate thickness is 0.0mm at a reduction rate of about 35%. It was rolled up to 88 times. The iron-to-aluminum intermetallic bond ratio of this steel plate was about 40%.

After rolling, the surface is adjusted by electrolytic degreasing and pickling, and then electrolytically chromated in chromic acid containing fluorine ions for 32 hours.
■A chromate film of g/rn' was formed.

Approximately 13 microns of vinyl chloride organosol paint was applied to one side of the steel plate (the surface corresponding to the inner surface of the can), and approximately 5 microns of epoxy paint was applied to the surface equivalent to the outer surface of the can. Thereafter, from a blank size of 173 mm, a can with a diameter of 65 mm and a height of 115 mm was drawn a total of three times.

A detailed observation of the coatings on the inner and outer surfaces of the can after drawing revealed that the hot-dip aluminum plating coating withstood the forming without any peeling, and the final product had perfect coverage of the iron. Furthermore, the coverage of the right m coating after processing was also good and not much different from that of conventional products.

Using this can, an actual can test was conducted using fish meat (seasoned with tuna flakes) as the content. After storage at 55°C for 6 months, the state of corrosion on the inner surface of each can was observed. Almost no abnormality was observed in the appearance, and when the steel plate surface was observed after removing the inner coating film with a solvent, several corrosion points were observed, but the corrosion reached the Fe base only in the M layer. However, it had practically excellent corrosion resistance.

Comparative Example 1 A steel plate with a thickness of 0.261 mm and a total of 25 microns on both sides.
Hot-dip aluminum plating containing % silicon
The alloy layer thickness was relatively thin at an average of 1.4 microns, and after 1.5% temper rolling (iron-aluminum metal bond was 1 tA), this steel plate was subjected to DI in the same manner as in Example 1. When subjected to molding, some surface roughness occurred after drawing on the second-stage surface, and peeling of the aluminum film was observed during the second and third stages of ironing. Peeling was observed.

Comparative Example 2 A steel plate with a thickness of 0.32 layers was coated with hot-dip aluminum to a total of 30 microns on both sides.The average thickness of the 0 alloy layer was 7.
4 microns, plate thickness 0.280 m at 20% reduction rate
It was rolled to m. The iron-to-aluminum intermetallic bond ratio of this steel plate was about 7%. When this steel plate was subjected to DI forming in the same manner as in Example 1, it was good up to the second drawing stage, but peeling of the aluminum film was observed in the second and third stages of ironing.

Comparative Example 3 A steel plate with a thickness of 0.80 m5 was coated with hot-dip aluminum to a total thickness of 50 microns on both sides.The average thickness of the zero alloy layer was 5.
3 microns, plate thickness 0.280 m at a reduction rate of 57%
It was rolled to m. The iron-aluminum intermetallic bond ratio of this steel plate was about 85%. When this steel plate was subjected to DI forming in the same manner as in Example 1, it showed excellent properties with no peeling of the aluminum film at all until ironing, but cracks occurred during flange forming after painting and printing.
A normal can body could not be obtained.

Comparative Example 4 A steel plate with a thickness of 0.32mm was coated with hot-dip aluminum to a total thickness of 18 microns on both sides.The average thickness of the 0 alloy layer was 2.
8 microns, plate thickness 0.280 m at a reduction rate of 17%
- It was rolled to -. The iron-to-aluminum intermetallic bond ratio of this steel plate was about 13%. When this steel plate was subjected to DI forming in the same manner as in Example 1, the aluminum film did not peel off during ironing, but numerous scratches occurred on the outer surface of the can, making it difficult to obtain a normal can body. I couldn't do it.

As described in detail, the present invention provides a hot-dip aluminum plated steel sheet for containers with excellent workability and corrosion resistance, a can body formed from the steel sheet, and a method for manufacturing the steel sheet, and is a useful invention.

Claims (1)

[Scope of Claims] 1. An iron-aluminum alloy layer on the surface of a thin steel plate, an aluminum film or an aluminum alloy film on the surface, and a broken part in the iron-aluminum alloy layer, and the broken part 1. A hot-dip aluminum-plated steel sheet for containers, characterized in that 10% or more of iron and aluminum coating or aluminum alloy coating are metallically bonded to each other through portions. 2. Using a hot-dip galvanized steel plate with an iron-aluminum alloy layer on the surface of the thin steel plate and an aluminum film or aluminum alloy film of 10 μm or more on the surface, the reduction ratio is 5.
Melting for containers characterized by cold rolling at a reduction rate of less than 0% and at a reduction rate that partially breaks the iron-aluminum alloy layer and metallurgically bonds the iron and aluminum film or aluminum alloy film by 10% or more. A method for manufacturing aluminum plated steel sheets. 3. A can based on a thin steel plate has an iron-aluminum alloy layer on both sides, and an aluminum film or an aluminum alloy film on the surface thereof, and the iron-aluminum alloy layer has a broken part, and the broken part It consists of a layer in which iron and aluminum film or aluminum alloy film are metallically bonded through a part, and the inner surface of the can further has a film or phosphate film containing a chromium compound in the outermost layer at least on the surface, and a paint film in that order. A can body featuring