JP2000273683A - Sn plated steel sheet with excellent corrosion resistance and workability - Google Patents

Abstract

PROBLEM TO BE SOLVED: To impart corrosion resistance and workability to a steel sheet by having a tin coating layer of a specific range in which a (101) face is included at a specific ratio on at least one surface of the steel sheet. SOLUTION: The tin coated steel sheet having the tin coating layer of 0.3 to 12 g/m2 into which the (101) face is included at >=20%, more preferably 20 to 80% on at least the one surface of the steel sheet is prepared. The method for applying the plating is executed by applying the tin coating by electroplating from an acidic bath of, for example, sulphuric acid or phenol sulfonic acid. A tin coating quantity and the integration degree of tin crystals are controlled by properly setting a current density, plating temperature, etc. The integration degree of the tin crystals is measured by a reflection X-ray diffraction method. Further, a chromate film of 2 to 20 mg/m2 in the quantity equivalent to metal Cr is imparted to the front surface of the steel sheet by subjecting the steel sheet to an immersion treatment in a chromic acid solution containing a sodium dichromate solution or to a cathode electrolytic treatment in order to prevent the discoloration to black or yellow by the oxidation of the tin coated steel sheet.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

TECHNICAL FIELD The present invention relates to a can material
In particular, the present invention relates to a Sn-plated steel sheet having excellent corrosion resistance and workability used for a two-piece can seam manufactured by drawing and ironing.

[0002]

2. Description of the Related Art At present, three-piece cans and two-piece cans are put to practical use as beverage cans. The types of cans are determined according to circumstances such as cost, corrosion resistance of the beverage to be packed, and distribution. I have. A three-piece can consists of three parts: a body, a lid, and a bottom. The body is formed by rolling a steel plate cut to a predetermined size into a cylindrical shape, and is mainly seam welded by a welding method developed by Sudronic. Is performed. As the steel sheet for three-piece cans, an Sn-plated steel sheet, a Sn / Ni-plated steel sheet, a Ni-plated steel sheet, and a steel sheet provided with a chromate film on these steel sheets are used.

[0003] A two-piece can has two parts, a body and a lid, and the body is formed by drawing and ironing. 2
Sn-plated steel sheets are used for piece cans.
The reason why the n-plated steel sheet is used is that Sn is relatively soft and rich in ductility, so that it works as an excellent lubricant at the time of drawing and ironing, and that it is a metal excellent in corrosion resistance.

[0004]

In recent years, two-piece cans have become more cost-effective and highly functional, and are required to have excellent workability and corrosion resistance that enable high-speed can making. To improve the corrosion resistance of two-piece cans, for example,
The invention disclosed in Japanese Patent Application Laid-Open No. Sho 62-13594 has been made. Although the present invention aims at improving the corrosion resistance of the base iron by adding another component (for example, Cr) to the base iron, it is true that the corrosion resistance is improved, but the other components are required to exhibit a sufficient effect. There is a problem in economical aspect that several% of addition is required. Further, in the present invention, no improvement in the processability of the two-piece can is expected.

[0005]

Means for Solving the Problems In order to meet the above-mentioned problems, the inventors focused on the texture of the Sn-plated layer of the Sn-plated steel sheet and made intensive studies. It has been clarified that by controlling, more excellent workability and corrosion resistance than before can be obtained. That is, S
By orienting 20% of the Sn crystal grains in the n-plated layer to the (101) plane, workability is remarkably improved more than before,
The lower the molding energy and the longer the tool life during continuous can making, and the more the orientation of the (101) plane increases,
It has been found that the corrosion resistance of the can wall and the bottom of the can after drawing and ironing is improved.

That is, the present invention provides: (1) at least one side of a steel sheet having a tin plating layer of 0.3 to 12 g / m ² containing at least 20% of a (101) plane and having excellent corrosion resistance and workability. Sn plated steel sheet. (2) At least one side of the steel plate has a (101) plane of 20 to 80.
% Sn-plated steel sheet having excellent corrosion resistance and workability, characterized by having a tin plating layer of 0.3 to 12 g / m ² . (3) At least one side of the steel plate has a (101) plane of 20 to 80.
% Of a tin plating layer containing 0.3 to 12 g / m ² , and a further upper layer of 2 to 20 mg in terms of metal Cr.
/ M ² , which has a chromate film and has excellent corrosion resistance and workability.

Hereinafter, the Sn-plated steel sheet which is excellent in the corrosion resistance and workability, which are the functions of the present invention, will be described in detail. In the present invention, the plating base sheet is not particularly limited, and a steel sheet usually used for drawing and ironing is used. The production method and material of the original plating sheet are not particularly limited, and the production is performed through the steps of normal rolling of a slab, hot rolling, pickling, cold rolling, annealing, pressure control, and the like.
When plating the plating base plate, usually, degreasing and pickling are performed as a pretreatment in order to clean the surface of the plating base plate, but these methods are not particularly limited, and for example, in 10% caustic soda. After degreasing, pickling may be performed in a 5% sulfuric acid solution.

[0008] Subsequent to degreasing and pickling, Sn plating is performed. As described above, Sn plating has an action for exhibiting excellent draw and iron workability and an action for improving corrosion resistance.
The plating amount needs to be 0.3 g / m ² or more. As the amount of Sn plating increases, workability and corrosion resistance improve.
If the amount of n plating exceeds 12 g / m ² , there is a problem in terms of economy. Therefore, the amount of Sn plating is restricted to 0.3 g / m ² or more and 12 g / m ² or less.

Further, 20% or more of the Sn crystals constituting the Sn plating layer must be integrated on the (101) plane. If the (101) plane is less than 20%, the above-mentioned excellent workability and corrosion resistance are not exhibited, and therefore, of the Sn crystal,
% Or more must be accumulated on the (101) plane. As the orientation of the Sn crystal accumulates on the (101) plane, the workability and corrosion resistance are improved, but even if it is 80% or more, the improvement effect is saturated. Therefore, economically, it is desirable that the accumulation of Sn crystals on the (101) plane be 80% or less.

The degree of integration of the Sn crystal can be measured by a reflection X-ray diffraction method. That is, as a standard sample, the diffraction intensity (I ₀ ) is measured using Sn crystal powder, and then the X-ray diffraction intensity (I ₁ ) of the Sn-plated steel sheet is measured by a reflection method. From the measurement results, the relative intensity ratio (I ₁ / I ₀ ) of each crystal orientation is calculated, and the sum is taken as the total amount, the accumulation ratio of each crystal orientation relative intensity is calculated, expressed as a percentage, and the It was the degree of integration. The method for performing Sn plating is not particularly limited. For example, Sn plating is performed by electroplating from an acidic bath such as sulfuric acid or phenolsulfonic acid, and S plating is performed.
The amount of n plating and the degree of Sn crystal integration may be controlled by appropriately setting the current density, the plating temperature, and the like.

Further, in order to prevent discoloration of the Sn-plated steel sheet to black or yellow due to oxidation, a chromate treatment is performed. By the chromate treatment, a hydrated Cr oxide or a chromate film composed of the hydrated Cr oxide and the metal Cr is provided, so that oxidation of the Sn plating layer can be prevented. In order to exhibit this effect, 2 mg / m2 in metal Cr equivalent amount
^It is necessary to apply ^two or more chromate films. As the amount of chromate coating increases, the effect of preventing the Sn plating layer from being oxidized is improved. However, if the amount exceeds 20 mg / m ² in terms of metal Cr, the effect is saturated, which is economically disadvantageous. Therefore, the chromate coating is 2 to 20 mg / m ^2.
Need to be The method of performing the chromate treatment is not particularly limited. For example, the chromate treatment can be performed by immersing in a sodium bichromate solution or a chromic acid solution containing a fluorine sulfate compound or by performing cathodic electrolytic treatment.

[0012]

EXAMPLES Examples and comparative examples of the present invention are described below, and the results are shown in Table 1. The cold-rolled, annealed, pressure-regulated plate having a plate thickness of 0.20 mm was treated with Sn ions:
Sn plating was performed in a sulfuric acid bath containing 25 g / l, and if necessary, the steel sheet was subjected to a cathodic electrolysis treatment in a sodium bichromate: 80 g / l solution to prepare a sample.

Regarding the above-mentioned processing materials, (A) shown below:
Performance evaluation was performed for each item of (B). (A) DI processability Using a DI molding machine, high-speed molding at a can making speed of 250 cpm was performed using a water-soluble emulsion type coolant, and the processability was evaluated in four stages (◎: extremely good, △: no practical problem) Good, Δ: Slight galling occurred and poor workability, ×: DI molding impossible).

(B) Corrosion Resistance An epoxy-phenol-based coating and baking were performed on the inner surface side of the DI molded can. 0.5
% Citric acid-0.5% saline solution, and after sealing, 5
After standing at 5 ° C. for 1 month, the corrosion state of the inner surface was evaluated in 4 stages (（: no corrosion was observed at all, Δ: very slight corrosion was observed to the extent that there was no practical problem, Δ: slight corrosion was observed ,
X: severe corrosion was observed in most cases). As a result, as shown in Table 1, a Sn-plated steel sheet having excellent workability and corrosion resistance can be manufactured.

[0015]

[Table 1]

[0016]

As described above, according to the present invention, a Sn-plated steel sheet having particularly excellent corrosion resistance and workability can be obtained as a material for can making.

Claims (3)

[Claims] 1. A steel sheet having at least one (101) face on one side
Sn having excellent corrosion resistance and workability, characterized by having a tin plating layer of 0.3 to 12 g / m ² containing 0% or more.
Plated steel sheet. 2. A steel sheet having at least one (101) face on one side.
S having excellent corrosion resistance and workability characterized by having a tin plating layer of 0.3 to 12 g / m ² containing 0 to 80%.
n-plated steel sheet. 3. The steel sheet has at least one (101) plane on one side.
It has a tin plating layer of 0.3 to 12 g / m ² containing 0 to 80% or more.
An Sn-plated steel sheet having excellent corrosion resistance and workability, characterized by having a chromate film of 20 mg / m ² .