JP2018168394A - Tin-plated steel sheet for can - Google Patents

Abstract

The present invention provides a tin-plated steel sheet for cans having good scratch resistance. A tin-plated steel sheet for cans having a tin-plated layer on the surface of the steel sheet. The arithmetic average roughness Ra in the plate width direction of the plating base steel sheet is 0.70 to 1.00 μm, and the tin adhesion amount per one side of the steel sheet is 2.45 to 3.2 g / m 2. The amount of chromium hydrated oxide on the surface of the tin plating layer is preferably 3 to 8 mg / m2. Alternatively, the amount of metal chromium on the surface of the tin plating layer is preferably 6 to 14 mg / m2. The preferred component composition is, by mass%, C: 0.03-0.05%, Si: 0.03% or less, Mn: 0.15-0.35%, P: 0.020% or less, S : 0.010-0.021%, sol. It contains Al: 0.020 to 0.064%, N: 0.0050% or less, with the balance being Fe and inevitable impurities. [Selection figure] None

Description

  The present invention relates to a tin-plated steel sheet for cans having excellent scratch resistance.

  Conventionally, tin-plated steel plates, which are typical steel plates for cans, have been used for food cans and beverage cans, 18L cans, 18L can bases, small cans (confectionery cans, tea leaf cans, etc.) and other uses. Yes. Since tin-plated steel sheets for cans have the characteristics of excellent content resistance, the inner and outer surfaces of cans are often used without painting.

  Since the tin plating film is soft, if used without coating, the surface of the steel sheet tends to be wrinkled during canning. Furthermore, wrinkles are likely to occur when the cans come into contact with each other in a stacked state after can molding.

  As countermeasures against the above problems, 1) To reduce the amount of tin adhered within the control range (thinning the soft tin plating layer) 2) To increase the lubricity, the amount of oil to be applied will be repelled Measures such as increasing the amount in a range not to be mentioned have been mentioned and implemented.

  In addition, for example, Patent Document 1 discloses a technique for improving tin peel resistance by using a tin-plated steel plate in which tin is partially electrodeposited on a steel surface as a steel plate for a can. The tin peel resistance is close to the scratch resistance in terms of the mechanical stability of the tin plating, but the tin peel resistance suppresses the peeling of the plating due to contact with a hard object. On the other hand, the scratch resistance suppresses deformation of tin plating due to contact with a hard object.

JP-A-10-121287

  However, the conventional method and the method described in Patent Document 1 cannot sufficiently prevent the generation of wrinkles.

  The present invention has been made for the purpose of solving the problems of the prior art as described above, and an object of the present invention is to provide a tin-plated steel sheet for cans having excellent scratch resistance.

  The present inventors have intensively studied to solve the above problems. As a result, it was found that increasing the arithmetic average roughness Ra in the width direction of the plating base steel sheet surface plate is more effective for the scratch resistance than the conventional steel sheet. Furthermore, it has been found that the soldering resistance is further improved by optimizing the amount of tin adhesion, the amount of metallic chromium, and the amount of chromium hydrated oxide.

  The mechanism by which increasing Ra is effective for scratch resistance is not clear. However, it is presumed that this is probably because the uneven projections when Ra is large have a thin plating layer, and the concave plating layers become thick, and the deformation of the plating layer is small at the projections where friction occurs.

This invention is made | formed based on such knowledge, The summary is as follows.
[1] A tin-plated steel sheet for cans having a tin-plated layer on the surface of the steel sheet, the arithmetic average roughness Ra in the width direction of the surface of the plated base steel sheet is 0.70 to 1.00 μm, and one side of the steel sheet A tin-plated steel sheet for cans, wherein the amount of tin adhered per unit area is 2.45 to 3.2 g / m ² .
[2] A tin-plated steel sheet for cans having a tin-plated layer on the surface of the steel sheet, the composition of which is by mass, C: 0.03-0.05%, Si: 0.03% or less, Mn: 0.15-0.35%, P: 0.020% or less, S: 0.010-0.021%, sol. Al: 0.020 to 0.064%, N: 0.0050% or less, the balance is made of Fe and inevitable impurities, the arithmetic average roughness Ra in the width direction of the plating base steel sheet surface plate is 0.70. It is 1.00 μm, the tin adhesion amount per one side of the steel sheet is 2.45 to 3.2 g / m ² , and the chromium hydrated oxide amount on the surface of the tin plating layer is 3 to 8 mg / m ^2. Tinned steel sheet for cans.
[3] A tin-plated steel sheet for cans having a tin-plated layer on the surface of the steel sheet, the composition of which is by mass, C: 0.03-0.05%, Si: 0.03% or less, Mn: 0.15-0.35%, P: 0.020% or less, S: 0.010-0.021%, sol. Al: 0.020 to 0.064%, N: 0.0050% or less, the balance is made of Fe and inevitable impurities, the arithmetic average roughness Ra in the width direction of the plating base steel sheet surface plate is 0.70. A can having a thickness of 1.00 μm, a tin adhesion amount per side of a steel plate of 2.45 to 3.2 g / m ² , and a metal chromium amount of 6 to 14 mg / m ² on the surface of the tin plating layer. Tin-plated steel sheet.
In addition, in this specification,% which shows the component of steel, and% which shows the component of plating are all the mass%.

According to the present invention, a tin-plated steel sheet for cans excellent in scratch resistance can be obtained. By using the tin-plated steel sheet for cans of the present invention, it is possible to prevent the occurrence of scratches on uncoated cans.
The tin-plated steel sheet for cans of the present invention is suitable as a material for 18L cans, 18L can bases, and small cans, as well as for food cans and beverage cans.

FIG. 1 is a diagram illustrating a method for confirming the state of wrinkling on the steel plate side. FIG. 2 is a view showing a state of wrinkling on the surface of the tin-plated steel sheet. FIG. 3 is a diagram showing the glossiness of the appearance of the tin-plated steel sheet.

  Hereinafter, the tin-plated steel sheet for cans of the present invention will be described in detail.

The arithmetic average roughness Ra in the width direction of the plating base steel sheet surface of the tin-plated steel sheet for cans of the present invention needs to be 0.70 to 1.00 μm. Uncoated cans are wrinkled by contact between cans even after the can molding process. In order to prevent this contact wrinkle, it is necessary to secure Ra of 0.70 μm or more. On the other hand, when the roughness increases, the tinted steel plate surface changes in whitish color, which causes a problem in appearance as a steel plate for cans. Therefore, Ra is set to 1.00 μm or less. From the viewpoint of scratch resistance, Ra is preferably 0.80 μm or more. The surface roughness of the plated steel sheet does not change even after tin plating. Therefore, if the tin plating of the tin-plated steel sheet is removed by a known method, the surface roughness of the base steel sheet of the tin-plated steel sheet can be measured.
The arithmetic average roughness Ra can be measured using a stylus type surface roughness meter in accordance with JIS B 0601 (2001).

As a component composition of the base steel plate of the tin plating layer for cans of this invention, the thing of the steel plate for cans generally used can be used. Among them, in mass%, C: 0.03-0.05%, Si: 0.03% or less, Mn: 0.15-0.35%, P: 0.020% or less, S: 0.010 -0.021%, sol. A cold-rolled steel sheet containing Al: 0.020 to 0.064%, N: 0.0050% or less, and having a composition composed of the balance of Fe and inevitable impurities is suitable. Furthermore, it can contain Cr: 0.01-0.06% for the reason mentioned later. Furthermore, 13 or more is more preferable as Mn / S which is ratio of Mn content and S content.
The reason for limiting the preferred range of each component will be described below.

C: 0.03-0.05%
C is an element having a large influence on the hardness of steel, and in order to obtain hardness products of T-1 to T-6 and DR-8 to DR-10, if the amount of C is 0.05% or less Well, the required product can be manufactured by satisfying the limiting conditions and setting the content according to the target hardness. On the other hand, if the amount of C is less than 0.03%, it becomes too soft for can applications. Therefore, the preferable range of the C amount is 0.03 to 0.05%.

Si: 0.03% or less Since Si is an element that extremely deteriorates the material of the tin-plated steel sheet for cans and further hardens the material, excessive inclusion of Si should be avoided. Therefore, the preferable range of the Si amount is 0.03% or less.

Mn: 0.15 to 0.35%
Mn is added in order to precipitate S that causes cracking of the hot-rolled coil as MnS and render it harmless. As the amount necessary for preventing the occurrence of ear cracks, it is sufficient if Mn is 0.05% or more, but in the present invention, since the deoxidizing power of Mn is also used, the preferable range of Mn amount is 0.15% or more. To do. On the other hand, since Mn is also a substitutional solid solution strengthening element, it is an effective component for producing an ultra-hard material, and is added as necessary. Therefore, the preferable upper limit is 0.35%.

P: 0.020% or less Since it is an element that hardens the steel sheet and deteriorates the corrosion resistance of the tin-plated steel sheet for cans, an excessive content is not preferable. Therefore, the preferable range of the P amount is 0.020% or less.

S: 0.010 to 0.021%
If S is contained in excess, it will cause cracks in the hot rolled coil. Therefore, the preferable range of the S amount is 0.021% or less. On the other hand, the plating property is improved by adding 0.010% or more. Therefore, a preferable lower limit is 0.010%.

sol. Al: 0.020 to 0.064%
It is an effective component for drastically reducing Al ₂ O ₃ inclusions. In order to obtain the effect even when combined with vacuum degassing, the preferable lower limit is made 0.020%. On the other hand, the preferable upper limit is 0.064% for economic reasons.

N: 0.0050% or less When dissolved in steel, a soft steel sheet is difficult to obtain, and is an unnecessary element. Therefore, the preferable range of the N amount is 0.0050% or less.

  The balance is Fe and inevitable impurities.

  Furthermore, in addition to the above preferred component composition, Cr can be contained. Cr is an element effective for strengthening steel and improving corrosion resistance. In order to exhibit such an effect, the Cr content is preferably 0.01% or more. On the other hand, if the Cr content exceeds 0.06%, the cost is significantly increased, so the upper limit is preferably 0.06%.

  Mn / S, which is the ratio of the Mn content to the S content, is preferably 13 or more for the purpose of preventing the occurrence of ear cracks in the hot rolled coil. By setting Mn / S to 13 or more, Mn is excessively added to S and MnS precipitates are easily formed, and S that causes ear cracking of the hot rolled coil can be rendered harmless.

The tin-plated steel sheet for cans of the present invention has a tin-plated layer on one or both surfaces of the steel sheet, and the tin adhesion amount per one surface of the steel sheet is 2.45 to 3.2 g / m ² . Moreover, you may have 3-8 mg / m < ² > of chromium hydrated oxide amount in the tin plating layer surface. Alternatively, the amount of metallic chromium may be 6 to 14 mg / m ^{2 on the} surface of the tin plating layer. In the case of a tin-plated steel sheet having metal chromium on the surface of the tin plating layer, 6 to 14 mg / m ² of chromium hydrated oxide may be formed on the surface of the metal chromium.

Tin adhesion amount: 2.45 to 3.2 g / m ²
If it is 2.45 g / m ² or more, the corrosion resistance as a steel plate for cans is sufficient. Therefore, the tin adhesion amount per one side of the steel sheet is set to 2.45 g / m ² or more. On the other hand, when the amount of tin adhesion exceeds 3.2 g / m ² , the amount of soft tin on the plating surface becomes excessive, so that the brazing resistance decreases. Therefore, it is 3.2 g / m ² or less. Preferably it is 2.6-3.0 g / m < ² >.
The tin adhesion amount can be determined by a wet analysis method. Specifically, for example, the entire plating layer of a test piece having a known adhesion area is dissolved in an aqueous solution obtained by adding 1 g / L of hexamethylenetetramine as an inhibitor to a 6% by mass hydrochloric acid aqueous solution, and the plating layer is determined from the mass loss at this time. What is necessary is just to obtain | require the adhesion amount.

The amount of metallic chromium and the amount of chromium hydrated oxide are specified in order to ensure corrosion resistance and scratch resistance.
(When there is no metallic chromium on the surface of the tin plating layer) The amount of chromium hydrated oxide is 3 to 8 mg / m ²
When there is no metallic chromium on the surface of the tin plating layer, discoloration may occur due to natural oxidation in the atmosphere. From the viewpoint of preventing discoloration, the hydrated chromium oxide is 3 mg / m ² or more on the surface of the tin plating layer. Preferably there is. Meanwhile, since it exceeds 8 mg / ^{m 2,} the effect is saturated, it is preferable that 8 mg / ^{m 2} or less.
(When the tin plating layer has metallic chromium) The amount of metallic chromium is 6 to 14 mg / m ²
Corrosion resistance is obtained by having metallic chromium on the surface of the tin plating layer. In order to obtain this effect, the amount of metal chromium is 6 mg / m ² or more. On the other hand, when the amount of metal chromium exceeds 14 mg / m ² , not only the effect is saturated, but also press workability is deteriorated, so the amount is made 14 mg / m ² or less. From the viewpoint of preventing discoloration due to natural oxidation in the atmosphere, the surface of the metallic chromium may further contain chromium hydrated oxide. In this case, the effect of preventing discoloration can be obtained when the hydrated chromium oxide is 6 mg / m ² or more. Meanwhile, the effect of hydrated chromium oxide content to prevent discoloration exceeds 14 mg / ^{m 2} is to saturate, it is preferably 14 mg / ^{m 2} or less.

The tin-plated steel sheet of the present invention can be produced, for example, by the following method. Hot rolling is performed on steel having the above component composition. Subsequently, it can manufacture by performing cold rolling, annealing, and temper rolling with respect to the obtained hot rolled sheet, and then performing a tin plating process.
At this time, the arithmetic average roughness Ra in the width direction of the steel sheet immediately before the tin plating process can be adjusted to 0.70 to 1.00 μm using shot blasting in any step before the tin plating process. Alternatively, a work roll whose arithmetic average roughness Ra in the roll width direction is 1.00 to 3.00 μm (preferably 1.15 to 1.35 μm) is used as a stand during temper rolling, and the steel sheet surface plate width direction. The arithmetic average roughness Ra may be 0.70 to 1.00 μm.
The tin plating treatment is performed so that the amount of tin adhered per side is 2.45 to 3.2 g / m ² . After the tin plating process, an Fe-Sn layer may be formed by performing an alloying process for diffusing Sn into the steel.

  The hydrated chromium oxide on the surface of the tin plating layer can be obtained by subjecting the tin-plated steel sheet obtained above to cathodic electrolysis in an aqueous sodium dichromate solution.

  The metallic chromium on the surface of the tin plating layer can be obtained by subjecting the tin-plated steel sheet obtained above to cathodic electrolysis in a high concentration chromic acid bath. When a cathodic electrolytic treatment is applied to a tin-plated steel sheet in a high-concentration chromic acid bath, metallic chromium is formed on the surface of the tin-plated steel sheet, and chromium hydrated oxide is further formed thereon. By performing immersion treatment in a low concentration chromic acid bath following this cathodic electrolysis treatment, a part of the chromium hydrated oxide is dissolved, and the chromium hydrated oxide can be brought into a desired amount of adhesion.

C: 0.04%, Si: 0.01%, Mn: 0.15%, P: 0.0060%, S: 0.008%, sol. Al: 0.062%, N: 0.0030% or less, with the balance being hot rolled, cold rolled, annealed on steel having a component composition consisting of Fe and inevitable impurities, then rolled Rate: Temper rolling was performed at 1.0 to 1.8%. In the temper rolling, the arithmetic average roughness Ra in the roll width direction of the work roll of the final stand was 1.10 to 1.40 μm. Subsequently, the tin-plating process by which the tin adhesion amount per one surface of a steel plate was 2.5-3.2 g / m < ² > was performed. Further, for some, a treatment for forming metallic chromium and / or chromium hydrated oxide on the surface of the tin plating layer was performed.

  As described below, the presence or absence of wrinkles and the gloss of the appearance of the tin-plated steel sheet obtained as described above were examined.

The presence or absence of wrinkling was tested by rubbing the surface of the tin-plated steel sheet a plurality of times with a constant pressure using a commercially available tissue by the method shown in FIG. Thereafter, the steel plate side was checked for evaluation of wrinkling. In addition, the speed | rate at the time of scraping off a tin plating steel plate with a permanent magnet was 1-3 second / cm. The tinning state of the tin-plated steel sheet after scraping five times was visually judged, and ◎ when there was no wrinkle, ○ when there was a slight wrinkle, and x when there was a wrinkle in question (Figure 2: (Refer to the picture of the date of the date.)

Evaluation was performed by visually checking the gloss of the appearance. Judgment was made by visual observation, and the case where it was appropriate was marked with ◯, the case where it was black was marked with Δ, and the case where it was whitish was marked with × (see FIG. 3: photograph of gloss evaluation).

  The evaluation results are shown in Table 1 together with the production conditions.

In the example of the present invention, a tin-plated steel sheet for cans having excellent scratch resistance is obtained.
In the above embodiment, the presence or absence of wrinkles was confirmed by a method of scraping the steel plate surface with a tissue, but the present invention is not limited to this. For example, the tin-plated steel plates after can making may be brought into contact with each other, or the tin-plated steel plate status after the can-making process may be confirmed. Even when this method is used, a tin-plated steel sheet having excellent scratch resistance can be obtained in the same manner as the method of scraping the steel sheet surface with a tissue.

Claims (3)

It is a tin-plated steel sheet for cans that has a tin-plated layer on the surface of the steel sheet,
The arithmetic mean roughness Ra in the width direction of the plating base steel sheet surface plate is 0.70 to 1.00 μm,
A tin-plated steel sheet for cans, wherein a tin adhesion amount per side of the steel sheet is 2.45 to 3.2 g / m ² . It is a tin-plated steel sheet for cans that has a tin-plated layer on the surface of the steel sheet,
The component composition is mass%, C: 0.03-0.05%, Si: 0.03% or less, Mn: 0.15-0.35%, P: 0.020% or less, S: 0.00. 010-0.021%, sol. Al: 0.020-0.064%, N: 0.0050% or less, the balance consists of Fe and inevitable impurities,
The arithmetic mean roughness Ra in the width direction of the plating base steel sheet surface plate is 0.70 to 1.00 μm,
A tin-plated steel sheet for cans, wherein a tin adhesion amount per side of the steel sheet is 2.45 to 3.2 g / m ² , and a chromium hydrated oxide amount on the surface of the tin plating layer is 3 to 8 mg / m ^2. . It is a tin-plated steel sheet for cans that has a tin-plated layer on the surface of the steel sheet,
The component composition is mass%, C: 0.03-0.05%, Si: 0.03% or less, Mn: 0.15-0.35%, P: 0.020% or less, S: 0.00. 010-0.021%, sol. Al: 0.020-0.064%, N: 0.0050% or less, the balance consists of Fe and inevitable impurities,
The arithmetic mean roughness Ra in the width direction of the plating base steel sheet surface plate is 0.70 to 1.00 μm,
A tin-plated steel sheet for cans, wherein a tin adhesion amount per side of the steel sheet is 2.45 to 3.2 g / m ² , and a metal chromium amount on the surface of the tin plating layer is 6 to 14 mg / m ² .