KR940002261B1 - Method for making a surface treatment steelsheet for draw and ironed can - Google Patents

Abstract

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Description

Manufacturing method of surface treated steel sheet for DI can

FIG. 1 is a schematic diagram of a hole-necked flange flange processing, in which solid lines show before processing and broken lines show after processing.

2 is a schematic diagram of a flange forming method with a widening of the hole diameter, in which solid lines show before processing and broken lines show after processing.

* Explanation of symbols for main parts of the drawings

1: Can side wall 2: Can end

3: can center portion 4: can bottom

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for producing surface-treated steel sheets for tin-plated DI cans (Draw & Ironed Can). A method for producing a surface-treated steel sheet for a DI can.

Background Art Conventionally, aluminum and tin-plated DI cans have been widely used as pressure-resistant beverage can containers such as carbonated drinks and beer.

The tin-plated DI cans are trimmed with a box-shaped annealing or continuous annealing tin-plating plate (about HR 30T: 49 earth 64) having a plate thickness of 0.25 to 0.35 mm, and then trimmed and finished. Then, it is manufactured by flange processing (blade cutting) for winding a lid.

Then, prior to the flange processing, processing for reducing the can tip end hole diameter, that is, necking processing, is performed.

For this reason, it is important for surface treatment steel plate for DI cans to be excellent in tightening workability, drawing workability, necking workability, flange workability, and corrosion resistance, and at the same time economical.

Here, as one of the methods of making it more economical than the DI can, it is necessary to make the plate thickness thin. In that case, it is necessary to use a material of high strength in terms of the internal pressure of the can.

Here, when the material is made of high strength, there is a problem of tightening and drawing workability, particularly flange workability.

Japanese Patent Application Laid-Open No. 51-88415 discloses deterioration of material strength and improvement of flange workability.

Japanese Patent Application Laid-Open No. 51-88415 defines a cold rolled structure having a rolling reduction of 80% or more by limiting the amount of C, S, or Al / C ratio of steel components to 0.02% or less, 0.01% or less, and 3.5 or more, respectively. The eggplant is made of a high strength steel sheet and improves the incidence of cracking in the flange forming method, that is, in flange processing to a few% level.

In this case, the cracking occurs in the flange processing because the flange processing is a process for widening the hole diameter of the can tip and is due to the lack of ductility of the material of the can tip.

The present invention is also the same as in Japanese Patent Laid-Open No. 51-88415 in terms of increasing the strength of the surface-treated steel sheet in order to make the DI can economical.

That is, the number of flange cracking incidence% of which Japanese Patent Laid-Open No. 51-88415 is excellent is much higher than that of about 10 ppm of the flange cracking incidence of the present box-shaped, annealing material, and continuous annealing material. In addition, it can be examined by the flange crack evaluation method of Japanese Patent Application Laid-Open No. 5l-88415. At the same time, in flange processing (figure 2) with the expansion of the hole diameter which is generally performed, Japanese Patent Application Laid-Open No. 51-88415 As shown in Fig. 1, the flange cracking improvement can be considered to be limited to the occurrence rate of several%.

Therefore, although it is a processing method incorporating various other problems, a flange can be formed without enlarging the hole diameter of the can tip end by tightening a portion which is inward in the can height direction from the can tip end in the radial half direction. The open-hole tightening system neck flange (FIG. 1) considered that it is the optimal method for applying a high strength steel plate to a DI can, and the research was made on the premise of this invention.

In other words, the combination of the hole tightening method and the neck flange processing was combined, and the examination was repeated to lead the surface treated steel sheet excellent in corrosion resistance and other moldability.

An object of this invention is to lead the surface-treated steel plate for high strength DI can which can make DI can more economical.

Here, as a means of making high strength, it was assumed that the annealing process currently performed is abbreviate | omitted.

That is, not only the cost reduction by high strength but also the reduction of annealing cost are aimed at.

In the case of applying such a high strength steel sheet to a DI can and performing a flange processing by a processing method (FIG. 2) that widens the diameter of the hole at the end of the can, the flange is considered to be unavoidable. The formation method was examined only by the above-mentioned opening hole tightening method neck flange processing (FIG. 1).

Although this open-hole tightening neck flange processing method is a process which reduces diameter, it is a process which pushes out with the decrease of a plate thickness, and flange cracking is hard to occur, but the surface becomes rough by processing, As a result, a coating film (塗膜) difficult cracking is likely to occur.

In addition, there is a problem in that a hole opening tightening can wall crack (a metal crack of a can wall occurring in the can diameter reduction portion slightly inside from the end of the can), flange wrinkles, etc. are also likely to occur.

As a result of numerous studies, the present invention has a high strength by eliminating the annealing process, and has the characteristics necessary for the open study tightening neck flange processing, and is excellent in corrosion resistance and other moldings. Will be able to lead the manufacturing method.

The reason for limitation is demonstrated below. C hardens steel as much as it increases and worsens drawing workability. On the other hand, when it decreases, drawing energy will be small, and drawing property will be improved, but it is unpreferable from the surface of the open-hole squeezing system neck-flange processing, and the crack of a coating film by the roughness of a surface, and the crack of processing of the can wall itself (entrance tightening crack) Easy to cause

For this reason, the upper limit and lower limit of the amount of C were determined.

When there is much Si, it hardens steel and it is easy to bring in a hole-hole tightening process, and the upper limit ratio was made into 0.03%.

Mn is also an element that hardens steel, and it is preferable to use a small one, but in order to prevent daily fragility caused by S, a relationship with the amount of S is added, and Mn / weight ratio is as small as possible, 7 to 14, preferably The following is taken as the amount of Mn of 7-10.

Here, S is added to 0.01% or more in order to improve the corrosion resistance of steel with respect to the beverage of high specific gravity as a beverage filled in DI can.

The upper limit of S was set at 0.03% because the amount of Mn added to harden the steel also needs to increase depending on the saturation of the effect on improving the corrosion resistance and the amount of S.

Al is added at least 0,02% or more due to deoxidation. If too large, grooves are easily formed on the surface, and cost is increased, so the upper limit is 0.01%.

Since N and P also harden steel very much, they are made into 0.006% or less and 0.03% or less, respectively.

The upper limit of the hardness after cold rolling is determined in relation to the wrinkle of the bottom of the can of the DI can.

Wrinkles occur radially on the bottom of the can at the time of bottom molding, but the appearance is impaired, which is undesirable.

The occurrence of wrinkles on the bottom of the can has a large influence on the degree and plate thickness, and when the hardness is increased, it is necessary to thicken the plate thickness on the surface of the wrinkle suppression, and the thinning, which is the purpose of increasing the strength, cannot be performed.

In this regard, the upper limit was set, and the lower limit was set to 73 as the lower limit of hardness (HR 30T) because the hardness below it could not be sufficiently reduced.

The plate thickness was determined in consideration of wrinkles and economics occurring in relation to hardness, and upper and lower limits.

Next, the reason for limitation of plating amount is demonstrated.

About the tin plating amount of the surface used as the outer surface of a can, when it becomes 1.0 g / m <2> or less, a groove will generate | occur | produce easily at the time of drawing processing, and continuous drawing processing will become difficult. Therefore, tin plating amount of the surface used as the outer surface of a can is 10 g / m <2> or more.

In addition, the minimum tin plating amount of the surface used as the inner surface side of a can was 0.1 g / m <2> in consideration of corrosion resistance, rust resistance, and stripping property (the characteristic which removes a can from a deviation | deflection). The lower limit of the plating amount of tin was 1.0 g / m 2 or more, and the upper limit of the plating amount was determined in consideration of economical efficiency both inside and outside.

In addition, it is preferable that the temperature of the winding after the daily rolling is preferably 600 ° C. or higher, and the processing energy at the time of DI porosity is due to the soft nitriding of the hot rolled sheet by the self-annealing and the reduction of the solid solution N. This is to reduce the number of holes and to improve the workability of the net and flange netting methods.

On the other hand, when the take-up temperature is set to 750 ° C or higher, the scale to be produced is difficult to remove by subsequent pickling.

For the above reasons, the upper and lower ends of the take-up temperature were determined.

Moreover, the preferable range of the rolling rate which cold-rolls a hot rolled sheet shall be 60 to 90%.

In the present application, the final plate thickness is 0.18 to 0.28 mm as described above. However, when the plate thickness is produced at 60% or less, the plate thickness of the hot rolled sheet needs to be about 0.5 mm or less.

In the hot rolled sheet manufacturing technology of the present state, when the plate | board thickness is about 0.5 mm, there exists a problem in the homogeneity of various characteristics.

Due to the homogeneity of the hot rolled sheet, the lower limit of the cold rolling rate was set to 60%.

In addition, the upper limit was set in consideration of tightening, drawing workability, open-hole simmering method, and net flange workability.

EXAMPLE

Hereinafter, an Example is described.

The steel shown in Table 1 was melted in the conversion furnace, and the steel piece of thickness 220mm created by continuous casting was made into the hot rolled sheet by hot rolling.

Then, it cold-rolled at the rolling ratio shown in Table 2. Subsequently, it was wiped clean and electroplated (2.8 g / m 2 on both outer surfaces).

Thereafter, by drawing and drawing, a drawing can of 211 size (65 mm in diameter) was used, and after spray coating, a flange was formed by an open-hole tightening method net flange processing.

Evaluation was performed about the tightening drawing workability (limit tightening ratio, drawing energy) about the wrinkles of the cans forming in the drawing processing step, the hole tightening cracks and the macrophage which are the coating cracks during the net flange processing.

Corrosion resistance was evaluated by using a phosphate beverage (cola) as a corrosion solution.

The Example of this invention is shown in Table 2 compared with a comparative material.

As is clear from the results of Table 2, the surface-treated steel sheet produced in the present invention is high in strength and excellent in tightening, drawing workability, can be wrinkled, open hole tightening method, net flange workability, and color resistance.

TABLE 1

TABLE 2

As described above, by defining the steel component, the manufacturing process, and the manufacturing conditions, the flange forming method after the drawing process is limited, but a very economical DI can can be provided.

Claims (2)

As weight ratio, C: 0.005% to 0.04%, Si: 0.03% or less, Mn: 0.1 to 04%, S 0.01 to 003%, Al 0.02 to 0.10%, N: 0.006% or less, P: 0.03% or less, and the remainder The hot rolled steel sheet made of iron and unavoidable impurities was subjected to annual rolling followed by cold rolling to set the hardness (HR30T) to 73 to 83 and the plate thickness to 0.18 mm to 0.28 mm, and then to the can outer surface and the inner surface of the can. Method for producing a surface of the DI can surface treatment steel sheet, characterized in that the tin plating of 1.0 to 11.0g / ㎡, 0.l to l1.0g / ㎡ in each of the surfaces. The method for producing a surface-treated steel sheet for DI can according to claim 1, wherein the winding-up temperature after hot rolling is 600 to 750 ° C, and the rolling rate of subsequent cold rolling is 60 to 90%.