KR890004621B1 - Method for producing a thin tin and nickel plated steel sheet for welded can material and product thereof - Google Patents

Abstract

A thin tin and nickel plated steel sheet for welded can is composed of 400-900 mg/m2 Sn coated layer on 5-20 mg/m2 Ni coated layer on both faces of a steel plate treated with chromite and is characterited by islands distributed discontinuously throughout the Sn coated layer due to heat melting treatment. The procedure is (1) anodizing under 3-30 C/dm2 in an alkaline solution with PH 10 or above, (2)Sn coating with 400-900mg/m2, and (3) heat melting at 240- 350≰C. This method can get good weldability and corrosion resistance, and is cheap.

Description

Surface-treated steel sheet for welded pipe and its manufacturing method

1 is an enlarged photograph showing a form in which metal Sn is distributed in an island shape of the present invention.

FIG. 2 is a chart comparing the degree of distribution of island-like distribution of metal Sn between anodization in an alkaline solution of the present invention and those not being performed.

3 and 4 are charts showing the effects of anodizing in an alkaline solution on the weldability and tolerability of the present invention, respectively.

BACKGROUND OF THE INVENTION Field of the Invention The present invention relates to an excellent surface-treated steel sheet for welding canning and its manufacturing method for filling and storing various foods and beverages.

Conventionally, the brazing method and the bonding method are known as a pipe manufacturing method for obtaining the tube of the container which fills and preserves a food or drink.

By the way, the pipe manufacturing method by electric resistance welding remarkably developed and spread | required in recent years, and the pipe | tube material which is cheap and excellent in weldability, corrosion resistance, and paintability has been calculated | required. The weldability of the electroplated steel sheet is extremely good, but Sn has been tried to reduce the amount of Sn plating to a minimum as long as the plated Sn is expensive and allows weldability, corrosion resistance and paintability.

However, only by reducing the amount of Sn plating, according to the decreasing amount thereof, these characteristics are gradually inferior, and in order to compensate for the inferiority of the characteristics when the Sn plating amount is about 1 g / m 2 or less, It is true that some improvement technology has been provided.

For example, in order to improve the corrosion resistance at a low Sn plating amount, a Ni-plated layer of 30 to 1000 mg / m 2 is formed on the surface of the steel sheet, and Sn-plating of 50 to 2000 mg / m 2 is performed thereon to perform heat melting treatment. Method (Japanese Patent Laid-Open No. 57-23091) was proposed.

In this method, by forming Ni on the surface of steel sheet, even if the amount of Sn plating was reduced, the amount of pinholes produced was small due to the synergistic effect of overlapping plating, and the total amount of plating combined with Ni and Sn plating amount was slightly reduced by the synergistic effect. Even if the required amount of Ni is in the range of 30 to 1000 mg / m 2, a wide range is required, and instead of expensive Sn, a part of Ni is replaced with Ni, which is never cheap.

下率)0.5~15%의 변형을 준후, 전기 도금으로 Sn을 100~1500mg/㎡을 시행하는 방법(일본국 특개소 60-33362호)이 제안되어 있다. 어느 것이나, Ni층 또는 Fe-Ni합금층에 의하는 내식성 향상을 주 목적으로한 것이다.In addition, Ni plating of 30 to 300 mg / m 2 is performed before annealing, and a part or all of Ni is diffused and penetrated into the surface of the steel sheet by heat during annealing to form a Fe-Ni alloy layer, and further by temper rolling. Rolling reduction (

The method of performing 100-1500 mg / m <2> of Sn by electroplating after giving 0.5-15% of deformation | transformation (Japanese Patent Laid-Open No. 60-33362) is proposed. In either case, the main purpose is to improve the corrosion resistance by the Ni layer or the Fe—Ni alloy layer.

In the conventional technique described above, in the case where the expensive Sn is plated thinly, the purpose of reducing the poor characteristics as much as possible by combining with Ni can be achieved. Since it is biased only in the improvement effect of corrosion resistance after a coating, the development of the welding pipe material which can satisfy both characteristics simultaneously is desired, The present invention aims at solving this problem simultaneously.

In order to solve such a problem, the present invention is to degrease the surface of the steel sheet in a usual manner, and then pickle it, and then, in an aqueous solution having a pH of 10 or more, an electric charge of 3 to 30 coulombs / dm 2 is applied to the surface of the steel sheet. After anodizing and subsequently electroplating 5 to 20 mg / m 2 of Ni, forming an electroplating Sn layer of 400 to 900 mg / m 2 and then performing a hot melt treatment, the metal Sn becomes a discontinuous island shape ( Nodular surface can be obtained, and the portion other than the island-like metal Sn becomes a rich surface of the Fe-Sn alloy layer and the Ni-Sn alloy layer, and is used as a surface-treated steel sheet for welding canning. It turns out that it has excellent weldability and corrosion resistance after painting.

On the other hand, by applying Ni plating of 2 to 30 mg / m 2 before Sn plating, to secure metal Sn necessary for good electric resistance weldability even after heating the coating, in Japanese Patent Application Laid-Open No. 60-56074, It is already proposed.

By the way, in this publication, only Ni plating amount and Sn plating amount are limited, Ni after the electroplating of 3-30 coulombs / dm <2> of electricity amount in the aqueous solution of pH 10 or more before Sn plating which is the most characteristic of this invention is Ni. By plating and again by heat-melting after tin plating, the metal Sn is simultaneously added to the surface rich in the Fe-Sn alloy layer and the Ni-Sn alloy layer, and to the discretely distributed island shape when observed from the surface. It is completely different from the features of the present invention to be present. As a result of investigating the relationship between the amount of Ni plating after anodizing in an aqueous solution having a pH of 10 or more before Sn plating and the distribution of metal Sn after heating and melting followed by Sn plating, as shown in FIG. 2, the amount of Ni was 5 to 20 mg. In the range of / m &lt; 2 &gt;, the metal Sn on the surface is distributed in a discrete island shape (see FIG. 1). When it exceeds 20 mg / m &lt; 2 &gt;, the surface Sn is uniformly distributed, which is a feature of the present invention. You will not be able to get the surface.

In the present invention, anodizing before 5 to 20 mg / m 2 of Ni plating is performed in an alkali solution having a pH of 10 or more, but the alkali solution is selected from hydroxides, carbonates, bicarbonates, and borate salts of alkali metals or ammonium. As the treatment liquid containing one or two or more kinds, both of them are subjected to anodization with an electric quantity of 3 to 30 coulombs / dm 2 as an alkaline aqueous solution having a pH of 10 or more.

The solution needs to be maintained at an alkalinity of pH 10 or higher, but the concentration of the alkali metal or the hydroxide of ammonium and the like is not particularly limited. If it dares to limit, 10-100 g / l is preferable. At 10 g / l or less, the bath voltage becomes high, which wastes power.

In addition, even 100 g / l or more does not adversely affect the effect aimed at by this invention especially, but is limited in terms of resource saving.

The amount of electricity in the anodizing treatment is effective from 3 coulombs / dm 2 or more, and even if it is 30 coulombs / dm 2 or more, there is no problem in securing the characteristics, but it is possible to carry out industrially easily. It is limited to coulombs / dm 2.

Even if the cathodic treatment is performed in the same bath before the anodization in the alkaline solution, the effect does not change, and the final polarity is good in the same bath. The temperature should just be normal temperature, and it does not need to heat especially. Ni plating performed following anodizing in aqueous alkali solution is performed by the normal Ni plating method.

For example, in the Watt bath _{NiSO4 · 6H 2 O 200 ~ 300g} / l, NiCl 2 · 6H 2 O 20 ~ 50g / l, H 3 BO 3 20 ~ 40g / l, in Sulphate acid bath sulfamate Ni 300 ~ 500g / l, H ₃ BO _{3 It} is performed under the conditions of the bath property of 20-40 g / l, current density of 2-30 A / dm <2>, and bath temperature of 30-70 degreeC.

In order to obtain the amount of Ni required for the present invention, it is possible to obtain cathode electrolysis of about 1 to 3 coulombs / dm 2 as approximately an electric quantity. The amount of Sn is more than 400 mg / m 2 on one side, because less than 400 mg / m 2 is not possible to obtain the island-shaped distribution of metal Sn which is the most characteristic feature of the present invention, and the upper limit of the amount of Sn is 900 mg / m 2 or less. If the amount exceeds 900 mg / m 2, the molten Sn increases and spreads uniformly over the entire surface, so that the surface characterized by the present invention cannot be obtained. Sn plating is usually carried out by the Sn plating method which is performed on an electroplated steel sheet, and the method is not particularly limited.

For example, as a phenol-sulfonic acid bath, and phenol sulfonic acid 10 ~ 30g / l (calculated as _{sulfate) SnSO 4 40 ~ 80g / l} , ethoxylated α-naphthol sulfonic acid 0.5 In the castle bath of 10g / l, temperature 30 It is performed on the plating conditions of -50 degreeC current density 5-50 A / dm <2>. Subsequent to Sn plating, after heating the temperature of the steel sheet to 240 to 350 ° C. for 1 to 3 seconds, a hot melt treatment for quenching is performed. By this heat-melting process, the Sn plating layer heated above the Sn melting point is melted and distributed in an island shape which becomes discontinuous by its surface tension.

Such discontinuous island-like distribution of the metal Sn is effectively achieved as a ratio by the base of Sn plating before annealing in alkaline solution, followed by Ni plating of 5 to 20 mg / m 2.

In the present invention, chromite-based post-treatment, which is widely known in the art, is performed on the uppermost layer for the purpose of improving paint adhesion, post-coating corrosion resistance, and unpainted corrosion resistance.

As the total chromium amount of this chromatic aftertreatment layer, it is necessary to set it as 3-20 mg / m <2> preferably 5-15 mg / m <2> per side. If the total chromium content is less than 3 mg / m 2, there is no problem in weldability, but it is not practical because it is inferior in corrosion resistance and uncoated corrosion resistance after coating.

On the other hand, if it exceeds 20 mg / m 2, in the case of the tube making method by welding, the electrical resistance becomes high, local overheating occurs easily during welding, and the needle shape (scattering) of molten iron tends to occur. Makes it bad

When metal chromium is contained in all the chromium amounts, it is preferable from a viewpoint of weldability that this metal chromium amount shall be 17 mg / m <2> or less. The amount of hydroxide chromium remaining after subtracting the amount of metal chromium from the total amount of chromium should be 3 mg / m 2 or more from the viewpoint of securing corrosion resistance after coating.

The chromite-based post-treatment in the present invention is prepared as a precipitant in a solution mainly composed of dichromic acid electrolytic post-treatment of electrolytic tin plated steel sheets or 30-100 g / l chromic acid, dichromic acid, and chromate salts. In a bath containing 1% or 2% sulfuric acid, sulfate, hydrofluoric acid, or fluoride of about 5%, cathode electrolysis is carried out at a temperature of 30 to 60 ° C and a current density of 5 to 20 A / dm 2.

Referring to the operation of the present invention.

As in the present invention, by distributing the metal Sn in an island shape, the contact resistance is low as shown in FIG. This is significantly improved.

性)이 현저하게 향상되어 있다. 알칼리 수용액 중에서의 양극처리 및 Ni도금층이, 가열 용융 처리후의 금속 Sn를 섬모양 형상으로 분포되게 하는 이유에 대하여는 명확하지는 않으나, 양극 처리에 의하여 생성되는 얇은 양극 산화 피막이, 그의 상층이 미량 Ni도금층과 서로 어울려서, Sn도금후의 가열 용융 처리시에 용융된 Sn가 부분적으로 튀기는 현상을 일으켜서, 금속 Sn가 섬모양 형상으로 분포되는 것으로 추정된다.In addition, as shown in FIG. 4, in the range of Ni amount 5-20 mg / m <2>, compared with the alkali pretreatment of this invention not being performed,

Sex) is remarkably improved. It is not clear why the anodizing and Ni plating layers in the aqueous alkali solution distribute the metal Sn after the heat-melting treatment in an island shape, but the thin anodizing film produced by the anodizing treatment has a trace amount of the Ni plating layer. It is estimated that the metal Sn is distributed in an island-like shape by causing a phenomenon in which molten Sn partially splashes at the time of the heat-melting process after Sn plating, in combination with each other.

In this way, the metal Sn is in an island shape, and a portion having a large amount of metal Sn is present locally, and the contact electrical resistance at the time of welding is lowered due to the flow effect of the metal Sn layer, and the weldability is considered to be improved. .

In addition, the portion other than the island-like metal Sn is a portion thinned by splashing the metal Sn, but becomes a surface rich in the dense Fe-Sn alloy layer and the Ni-Sn alloy layer, contributing to improvement of corrosion resistance after coating. As a result, it is estimated that both characteristics of weldability and coating corrosion resistance can be acquired simultaneously.

EXAMPLE

Next, the method of implementing this invention is demonstrated.

A 0.20 mm thick mild steel sheet, which was cold rolled by a conventional method carried out in the production of electroplated steel sheet, was continuously annealed and temper rolled.

Ni plating baths used in Examples and Comparative Examples, watt bath (NiSO ₄ · 6H ₂ O 250g / l, NiCl ₂ · 6H ₂ O 30g / l, H ₃ BO ₃ 40g / l) and sulfamic acid bath (sulpa Ni 350N / l, H ₃ BO ₃ 40g / l) was used.

The Sn plating bath uses a phenol sulfonic acid bath (Sn 60g / l, sulfate phenol sulfonic acid 30g / l ethoxylated alpha naphthol sulfonic acid 5g / l) and an alkali bath (80 g / l caustic soda 15g / l). do. The heat-melting process was performed by performing water cooling immediately after heating up the board temperature to 280 degreeC for 1.6 second.

Table 1 shows the processing steps and characteristics evaluation results of the examples and the comparative examples.

性)모두가 뒤떨어져 있다.In Comparative Example 1, the anodic treatment in the alkaline solution was not performed, but the metal Sn became a uniform distribution, and the weldability and the cold-resistant property

All are inferior.

The comparative example 2 is an example in which the heat-melting process required for distributing the metal Sn in an island shape is not carried out, but in particular, the magnetic resistance is insufficient.

In Comparative Example 3 in which the amount of Ni was out of the range of the present invention, the weldability was inferior even though the corrosion resistance after coating was excellent.

In addition, Comparative Example 4 is an example in which the amount of Sn is out of the range of the present invention, but the surface metal Sn does not become an island-shaped distribution, and is inferior in both weldability and post-painting corrosion resistance.

In an Example and a comparative example, a characteristic evaluation method is demonstrated next.

(1) Wire joint weldability test

Wire joint weldability is represented by the difference between the electric current lower limit necessary for the mechanical strength of the weld to exceed the base material strength and the upper limit current that causes scattering in the weld. The larger the difference, the better the wire joint weldability. The secondary part and two surface-treated steel sheets for welding canning are overlapped, sandwiched between two disk electrodes, and rotated at an ambient speed of 5 m / min, flowing a 5 A direct current to measure the voltage between the electrodes. There is a good inverse of resistance. Therefore, as an index of weldability, it appeared as the contact resistance after 20 minutes of heating at 210 degreeC.

(2) Corrosion resistance test after painting

(Internal tablet test)

)을 4단계 법으로 평가 하였다.The vinyl organosol is coated with 75 mg / m 2, heat-bonded at 200 ° C. for 10 minutes, and after adding scratches to reach the iron soil, the erythsen processing is performed by 5 mm, and after immersion in 3% saline for 1 hour, the brine is wiped off. And left for 10 days in an antigen barrel with a relative humidity of 85% at 45 ° C.

) Was evaluated by a four-step method.

(Uncut Cutting Corrosion Test: UCC)

65 mg / m <2> coating of phenol epoxy coating was carried out, and it heat-bonded at 210 degreeC for 10 minutes, and the "+" character scratch was put in the load of 200 gr. It was immersed in 1.5% citric acid + 1.5% saline solution, degassed with nitrogen gas, and stored at 37 degreeC for 15 days. After the test, the extent of corrosion and the degree of corrosion in the scratches of the samples were evaluated by a four step method.

As described in detail above, the effect of the present invention is that when Sn is plated thinly, by distributing the metal Sn on the surface in an island shape as in the present invention, it has good weldability and post-painting corrosion resistance. Excellent welding pipe material could be obtained.

Table 1

Embodiment of the present invention. Treatment process and evaluation results of the comparative example

약간뒤떨어짐, ×뒤떨어짐.Evaluation symbol: ◎ Significantly good, O good,

Slightly backward, × backward.

Claims (2)

In a plated steel sheet which forms a Ni-plated layer of 5-20 mg / m 2 per side on a steel plate surface, a Sn-plated layer of 400-900 mg / m 2 thereon, and a chromite-based post-treatment layer thereon, the Sn-plated layer is subjected to heat-melting treatment. The surface-treated steel sheet for weld can manufacturing, characterized in that the discontinuous island-shaped distribution form. The surface of the steel sheet was first subjected to anodizing at 3 to 30 coulombs / dm 2 in an alkaline aqueous solution having a pH of 10 or more, followed by Ni plating at 5 to 20 mg / m 2, followed by 400 to 900 mg / m 2 Sn plating. And then heat-melting at a temperature of 240 to 350 ° C. to form this plated Sn into a discontinuous island-shaped distribution, and then performing a chromite-based post-treatment steel sheet Manufacturing method.

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