JP2000087298A - Surface-treated steel sheet excellent in high-speed seam weldability, adhesion, and corrosion resistance, and method for producing the same - Google Patents

Abstract

(57) Abstract: The present invention provides a steel plate for a welding can as a material for a can, which is particularly excellent in high-speed seam weldability, adhesion of paints and films, and corrosion resistance, and a method for producing the same. SOLUTION: The surface of the steel sheet is subjected to Ni plating, and an oxide chromium layer having a metal chromium equivalent of 1 to 15 mg / m ² and an oxo compound ratio of 60 to 95% is formed thereon. High-speed seam weldability, adhesion,
Surface treated steel sheet with excellent corrosion resistance.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

TECHNICAL FIELD The present invention relates to a can material
Especially high-speed seam weldability, adhesion of paint and film,
The present invention relates to a steel plate for a welding can excellent in corrosion resistance and a method for producing the same.

[0002]

2. Description of the Related Art In recent years, the technology for making welded cans by the wire seam resistance welding method has rapidly progressed, and its practical application in the field of beverage cans has rapidly progressed. As a steel sheet for a can used in this type of welding can, a material for a can made by modifying a chromic acid film on a Ni plating surface (Japanese Patent Publication No. 36-15252) is known. Further, JP-A-57-35697 and JP-A-57-35698 provide a production method capable of improving weldability and corrosion resistance after painting. Certainly, such a manufacturing method according to the present invention has weldability, corrosion resistance,
An object of the present invention is to provide a surface-treated steel sheet for welding cans having paint adhesion. However, in these methods in which hydrated chromium oxide (hereinafter referred to as Ox-Cr) is formed by performing cathodic electrolysis in a chromic anhydride-based treatment bath containing a fluorine compound as an auxiliary, Ox- C
It is difficult to stably obtain the necessary amount of Ox-Cr for dissolving r.

[0003]

In recent years, further progress in can-making technology and reduction in can-making cost have led to an increase in can-making speed in order to greatly improve the productivity of the can-making process. I have. However, when the canning speed is increased, the applicable welding current range (ACR) is reduced, and welding defects are likely to occur. This is because the electrical resistance of oxide chromium, which constitutes the chromate coating for adhesion and corrosion resistance, is extremely high, and the melting point is high and the electrical resistance is high. This is because even at the adhesion amount level, there is an adverse effect when the speed is increased. Simply reducing the amount of chromate adhering causes a decrease in other properties (adhesion, corrosion resistance). It has been found that it is important to strictly control the quality and quantity of oxide chromium in order to improve the high-speed seam weldability without lowering the adhesion and corrosion resistance characteristics.

[0004]

The gist of the present invention is as follows. (1) A high-speed seam characterized in that a steel plate surface is subjected to Ni plating and an oxide chromium layer having a metal chromium equivalent of 1 to 15 mg / m ² and an oxo compound ratio of 60 to 95% is formed thereon. Surface treated steel sheet with excellent weldability, adhesion and corrosion resistance. (2) Ni plating amount per side of steel plate is 150 to 250
The surface-treated steel sheet excellent in high-speed seam weldability, adhesion, and corrosion resistance according to the above (1), which is 0 mg / m ² .

[0005] (3) performing Ni plating on the steel sheet surface, contains H ₂ SO ₄ of 1 / 50-1 / 200 in a weight ratio of CrO ₃ and CrO ₃ of 35～200G / l thereon balance water And a cathodic electrolysis in a cathodic electrolysis bath having a bath temperature of less than 45 ° C. comprising unavoidable impurities.
g / l CrO ₃ , immersion treatment in a bath consisting of water and inevitable impurities at a bath temperature of 45 ° C. or higher, and the surface of the Ni-plated steel sheet is 1 to 15 m in terms of metallic chromium.
A method for producing a surface-treated steel sheet having excellent high-speed seam weldability, adhesion, and corrosion resistance, which comprises forming an oxide chromium layer having a ratio of g / m ² and an oxo compound of 60 to 95%.

(4) CrO in the immersion bath_ThreeWeight ratio with
H of 1/50 to 1/200_TwoSO _FourAnd inevitable impurities
A high-speed seam according to the above (2),
How to manufacture surface-treated steel sheets with excellent weldability, adhesion, and corrosion resistance
Law. (5) Ni plating amount per side of steel plate is 150 to 250
0mg / m^Two High-speed seam welding according to the above (3),
Method for producing surface-treated steel sheets with excellent heat resistance, adhesion and corrosion resistance
is there.

Hereinafter, a surface-treated steel sheet excellent in high-speed seam weldability, adhesion, and corrosion resistance, which is an effect of the present invention, and a method for producing the same will be described in detail. In the present invention, the plating base sheet is not particularly limited, and a steel sheet used as a container material is usually used. Production method of plating base sheet,
The material and the like are not particularly limited, and the slab is manufactured through the steps of a normal billet manufacturing process, hot rolling, pickling, cold rolling, annealing, tempering, and the like. Further, the original plating sheet may be manufactured by a process of performing cold rolling, annealing, and then re-cold rolling (that is, 2CR method) according to the required can body strength and sheet thickness.

[0008] The above-mentioned plated original plate is usually degreased and pickled as a pretreatment in order to normalize the surface of the plated original plate, but these methods are not limited.
After degreasing in 10% caustic soda, pickling may be performed in a 5% sulfuric acid solution. Ni plating is performed following degreasing and pickling. Since Ni is a highly corrosion-resistant metal, by plating Ni, the corrosion resistance of the plating layer can be improved. The effect of improving the corrosion resistance of the plating layer by Ni is exhibited when the Ni plating amount per side is 150 mg / m ² or more. Therefore, the amount of Ni plating is extremely desirably 150 mg / m ² or more. As the amount of Ni plating increases, the effect of improving the corrosion resistance of the plating layer increases.
When the amount is 0 mg / m ² or more, the effect of increasing the amount is not recognized, and the amount of Ni plating at which economic loss increases is 2500
mg / m ² or less.

After Ni plating, adhesion to film and paint, corrosion resistance (prevents undercutting corrosion)
An oxide chromium film is applied for the purpose. Oxide chromium includes all-type oxide chromium and oxo-type oxide chromium, and a film having a high ratio of oxo-type oxide chromium has high adhesion. Oxo-type oxide chromium ratio = 100 × oxo-type oxide chromium amount / total oxide chromium amount The effect is exhibited when the ratio of the oxo-type oxide chromium is 0.60 or more, and when the ratio is 0.95 or more, on the contrary, the adhesion deteriorates. .

Further, since the oxide chromium coating has an extremely high electric resistance due to its electrical insulation, both are negative factors which deteriorate the weldability. For this reason, a proper amount of oxide chromium that does not deteriorate good film and paint adhesion, corrosion resistance and practically high-speed seam weldability is very important. Therefore, the amount of oxide chromium is 1 to 15 mg / m ^{2 in} terms of metallic chromium per side.
It is. That is, if the amount of the chromate film attached is less than 1 mg / m ² (in terms of chromium metal), the effect of improving the adhesion of the film or paint cannot be obtained, and the amount of the chromate film attached is 1
When it exceeds 5 mg / m ² , the contact resistance starts to increase suddenly,
During high-speed seam welding, dust is easily generated due to local heat generation, and weldability is deteriorated.

Oxide chromium deposition is performed by cathodic electrolysis in a chromate treatment bath in which sulfuric acid is added as a plating aid to a bath of chromic anhydride. It is difficult to form an oxide chromium film having the above-described structure only by electrolysis in a chromate treatment bath. Therefore, it is necessary to generate highly soluble all-type oxide chromium during electrolysis and then dissolve the all-type oxide chromium in a chromic acid bath. The solubility of the all-type oxide chromium is determined by the bath temperature at the time of electrolysis, and increases as the bath temperature decreases.
In particular, the solubility of the all-type oxide chromium is remarkable below 45 ° C., and it is preferable to set 45 ° C. as the upper limit of the bath temperature during electrolysis. The lower limit of the bath temperature at the time of electrolysis is not particularly defined. However, if the temperature is too low, it is uneconomical due to the necessity of installing a refrigerator or increasing the capacity.

As described above, in order to form a uniform oxide chromium with a low adhesion amount, it is desirable that the concentration of CrO ₃ contained in the electrolytic treatment bath is 35 g / l or more. It is desirable to set the upper limit to 200 g / l because the adhesion is reduced. The addition of sulfuric acid to the treatment bath is indispensable for the production of the desired oxide chromium, and it is necessary to make the weight ratio to chromic anhydride (hereinafter referred to as sulfuric acid concentration ratio) 1/300 to 1/50.
If the sulfuric acid concentration ratio is too high or too low, its effect is significantly reduced, so the lower limit of the sulfuric acid concentration ratio is 1/200 and the upper limit is 1/50.

The treatment bath may contain a fluorine compound such as sodium fluorosilicate, sodium borofluoride, or ammonium fluoride as a Me-Cr deposition aid in addition to sulfuric acid. If the amount of trivalent chromium ion mixed in the treatment bath is 0.1 to 5 g / l, it may be mixed because it is effective in making the chromate film uniform. Further, the dissolving ability of the generated all-type oxide chromium increases with an increase in the temperature of the chromic acid bath, and is particularly remarkable at 45 ° C. or higher. Although the upper limit of the chromic acid bath temperature is not particularly defined, if the temperature is too high, the fume recovery of the bath becomes large and it is uneconomical. Therefore, it is preferable to set the upper limit to 70 ° C. Further, when the chromic anhydride concentration is less than 35 g / l, all-type O
Since the ability to dissolve x-Cr is remarkably reduced, a concentration higher than this is desirable. If the concentration is higher than 200 g / l, the etching action is too strong and the oxo-type Ox-Cr is also dissolved, so that the paint adhesion, May lead to a decrease in corrosion resistance. Therefore, the upper limit of the chromic anhydride concentration is set to 200 g / l.
It is desirable that Preferably, it is 50 g / l or less.

[0014]

EXAMPLES Examples of the present invention and comparative examples are described below, and the results are shown in Table 1. The cold rolled or twice rolled after annealing, the plating original sheet adjusted to a predetermined thickness is electrolytically degreased in 5% caustic soda, washed with water, electrolytically pickled in 10% sulfuric acid, and subjected to surface treatment after surface activation. Was. After Ni plating was performed on the original plate under the conditions shown in (1), chromate electrolysis was performed under the conditions shown in (2) to form a chromate film, and then oxide chromium was deposited under the conditions shown in (3). A solution was prepared.

(1) Ni Plating Conditions Plating composition _{NiSO 4 · 6H 2 O 70g /} l NiCl · 6H 2 O 140g / l H 3 BO 3 30g / l electrolysis conditions 5A / dm ² 50 ° II. Plating bath composition _{NiSO 4 · 6H 2 O 70g /} l NiCl · 6H 2 O 140g / l H 3 BO 3 30g / l electrolysis conditions 10A / dm ² 50 ° III. Plating bath composition _{NiSO 4 · 6H 2 O 140g /} l NiCl · 6H 2 O 140g / l H 3 BO 3 30g / l electrolysis conditions 5A / dm ² 50 °

(2) Chromate treatment (cathode treatment) conditions The test piece prepared in (2) is immersed in a bath having the following plating composition for electrolysis. The electrolysis time is adjusted according to the plating amount. Chromic acid 20 to 300 g / l sulfate ion (weight ratio of CrO ₃₎ 1 / 300~1 / ₃
0 Electrolysis conditions 10-60 ° C 10A / dm ²

(3) Chromate treatment (oxide chromium dissolution treatment) conditions The test piece prepared in (3) is immersed in a bath having the following bath composition. The immersion time is arbitrarily adjusted. Chromic acid 20-300 g / l Dissolution condition 30-70 ° C

Regarding the above-mentioned processing materials, (A) to
Each item of (D) was performed, and the performance was evaluated. (A) High-speed seam weldability
Baking was performed under a temperature-raising condition of 23 seconds to 20 ° C., and high-speed seam weldability was evaluated under the following welding conditions. Under the conditions of a lap margin of 0.5 mm, a welding pressure of 45 kgf, and a welding wire speed of 100 m / min, the current is changed and the welding is performed. Judging comprehensively from the width of the appropriate current range consisting of the values, the evaluation was made in three stages (（: very wide, Δ: no problem in practical use, ×: narrow).

(B) Adhesion of paint The epoxyphenol-based paint is applied at 55 mg / dm ² on the surface corresponding to the inner surface of the can of the test piece, and the clear lacquer is applied at 40 mg / dm ² on the surface corresponding to the outer surface of the can. ,
Drying and curing were performed under a baking condition of 15 seconds up to 290 ° C. Subsequently, scratches were made on each surface at intervals of 1 mm to prepare 100 grids, the tape was peeled off promptly, the peeling state was observed, and three stages (、 ３: no peeling,
Δ: 1 to 4 pieces peeled, ×: 5 or more pieces peeled) to evaluate paint adhesion.

(C) Film Adhesion Evaluation Test After laminating a 15 μm thick PET (polyethylene terephthalate) film on a test piece, make a cross cut until it reaches the ground iron, and immediately heat it to 240 ° C. 5 kg / cm ² air gas was blown vertically to the center of the cut, and the peeling state of the film was evaluated in three stages (◎: no peeling, Δ: slight peeling, ×: peeling mostly).

(D) UCC (Undercutting Corrosion) Evaluation Test In order to evaluate the corrosion resistance of the surface of the test piece corresponding to the inner surface of the can,
A PET (polyethylene terephthalate) film having a thickness of 15 μm was laminated on a surface corresponding to the inner surface of the can.
After that, make a cross cut until the steel reaches 1.5%
It was immersed in a test solution composed of a citric acid-1.5% salt mixture at 55 ° C. for 4 days in the open to the atmosphere. After the test is completed, the scratch part and the flat part are immediately peeled off with a tape, and the corrosion state near the scratch part, the pitting state of the scratch part, and the film peeling state of the flat part are evaluated in three stages. Not observed, Δ: slight peeling but no corrosion was observed, x: peeling was observed in most parts and severe corrosion was observed). As shown in Table 1, it was revealed that the steel sheet for a welding can produced according to the present invention had excellent high-speed seam weldability, adhesion and corrosion resistance.

[0022]

[Table 1]

[0023]

As described above, the steel sheet for a welding can manufactured according to the present invention can provide an extremely excellent steel sheet having excellent high-speed seam weldability, adhesion and corrosion resistance.

 ──────────────────────────────────────────────────続 き Continuation of the front page (72) Inventor Kazunari Hasegawa 1-1-1, Tobata-cho, Tobata-ku, Kitakyushu-shi, Fukuoka F-term in Nippon Steel Corporation Yawata Works (reference) 4K024 AA02 AA03 AB02 BA03 BB22 CA01 CA04 CA06 GA04 GA15

Claims (5)

[Claims] 1. A steel sheet is coated with Ni plating, and an oxide chromium layer having a metal chromium equivalent of 1 to 15 mg / m ² and an oxo compound ratio of 60 to 95% is formed thereon. Surface treated steel sheet with excellent high speed seam weldability, adhesion and corrosion resistance. 2. The amount of Ni plating per side of a steel sheet is 150.
~ 2500mg / m ^Two 2. The high-speed seam according to claim 1, wherein
Surface treated steel sheet with excellent weldability, adhesion and corrosion resistance. 3. A plated with Ni on the steel sheet surface, in a weight ratio of CrO ₃ and CrO ₃ of 35～200G / l thereon 1 / 50-1 / 200 balance water and containing H ₂ SO ₄ of Cathodic electrolysis is carried out in a cathodic electrolysis treatment bath having a bath temperature of less than 45 ° C consisting of unavoidable impurities, followed by 35 to 200 g /
The immersion treatment was carried out in an immersion treatment bath having a bath temperature of 45 ° C. or higher containing 1 CrO ₃ and the balance consisting of water and unavoidable impurities.
1 to 15 mg / m in metal chromium equivalent on the surface of i-plated steel sheet
^{2. A} method for producing a surface-treated steel sheet excellent in high-speed seam weldability, adhesion, and corrosion resistance, comprising forming an oxide chromium layer having an oxo compound ratio of 60 to 95%. 4. A weight ratio of 1 to CrO _{3 in the} immersion bath.
/ 50-1 / 200 of the H ₂ SO ₄ and the high-speed seam weldability according to claim 2, characterized in that it comprises unavoidable impurities, adhesion method for producing a superior surface-treated steel sheet corrosion resistance. 5. The amount of Ni plating per side of a steel sheet is 150.
~ 2500mg / m ^Two 4. The high-speed seam according to claim 3, wherein
How to manufacture surface-treated steel sheets with excellent weldability, adhesion, and corrosion resistance
Law.