JP3806242B2 - Steel plate for containers with extremely small earrings during drawing and method for producing the same - Google Patents

Description

【００２０】
【表２】

【００２１】
【発明の効果】
以上述べた如く本発明によれば、製缶時の鋼板歩留まり、生産性を改善できる絞りイヤリング発生が小さな極薄容器用鋼板を高い冷延率で製造することができる。
【図面の簡単な説明】
【図１】鋼板の耳発生の程度をカップ胴壁高さとカップ周位置の関係で表す図。
【図２】Ｃ量との関連でイヤリング率に及ぼすＳｎ，Ｂ添加の効果を示す図。
【図３】表１の鋼ａ，ｂ，ｃについて焼鈍温度とイヤリングの関係を示す図。[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a steel plate used for a container formed by processing including drawing, such as a beverage can represented by a two-piece can, and a method for manufacturing the same.
[0002]
[Prior art]
In beverage cans and food cans that are sealed containers by tightening the can lid around the opening of the integrated can body obtained by drawing and ironing, the steel plate yield and iron moldability are reduced. It is desired to reduce the occurrence of earrings during molding. However, in recent years, with the aim of reducing the cost by reducing the materials used, reduction of the plate thickness (extremely thin) of the container material has been directed, and there is a concern about the increase in earrings as will be described later.
[0003]
It is well known that earrings are generated due to anisotropy in the in-plane orientation of a plastic anisotropy (Rankford value) due to the texture of the steel plate. Various studies have been made to reduce the in-plane anisotropy. However, in the current container material, if the cold rolling reduction ratio is set high in order to achieve ultrathinning, the number of earrings increases. In this situation, a method for manufacturing a steel plate with small earrings is disclosed in Japanese Patent Laid-Open Nos. 5-287445, 7-41916, and 7-11333.
[0004]
However, although the conventional methods are effective even when the cold rolling reduction is about 80 to 90%, the method is not particularly aimed at lowering the earrings at a high cold rolling ratio, and therefore, it is intended to be extremely thin. Therefore, when the cold rolling rate is set high, the number of earrings increases, and the earrings made of ultrathin materials cannot be sufficiently satisfied.
[0005]
[Problems to be solved by the invention]
The present invention provides a steel sheet and a method for producing the same, in which the earrings at the time of drawing are significantly reduced particularly in an ultrathin container material produced at a high cold rolling ratio of 90% or more.
[0006]
[Means for Solving the Problems]
The present inventor limited the amount of C to a specific range while examining the effect of Sn disclosed in Japanese Patent Application Laid-Open Nos. 7-41916 and 7-11333, particularly the relationship between trace added elements and earrings. And, it was found that the earrings are remarkably suppressed by the steel sheet to which Sn and B are added in combination. Further, the present invention has been completed by further studying the cold rolling reduction ratio, the annealing temperature, and the like.
[0007]
That is, the gist of the present invention is as follows.
(1) in mass%,
C: 0.015-0.060%, Si: 0.001-0.5%,
Mn: 0.02 to 1.0%, P: 0.002 to 0.08%,
S: 0.002 to 0.05%, Al: 0.010 to 0.100%,
N: 0.0005 to 0.0060%, Sn: 0.003 to 0.100%,
B: 0.0002 to 0.0030%
A steel plate for containers which contains a balance Fe and unavoidable impurities and has a thickness of 0.4 mm or less and has a remarkably small earring during drawing.
[0008]
(2) mass%,
C: 0.015-0.060%, Si: 0.001-0.5%,
Mn: 0.02 to 1.0%, P: 0.002 to 0.08%,
S: 0.002 to 0.05%, Al: 0.010 to 0.100%,
N: 0.0005 to 0.0060%, Sn: 0.003 to 0.100%,
B: 0.0002 to 0.0030%
The hot rolled sheet containing the balance Fe and inevitable impurities is cold-rolled at a reduction rate of 70 to 98%, annealed at a recrystallization temperature of 800 ° C. or less for 3 minutes or less, and a reduction rate of 0.5 Production of a steel plate for a container having a remarkably small earring at the time of drawing, characterized by re-rolling so that the total cold rolling reduction ratio from hot rolled sheet to final product is 92 to 98 %. Method.
( 3 ) The method for producing a steel plate for containers according to item (2) above, wherein the earring at the time of drawing is extremely small, wherein the annealing temperature is 550 to 680 ° C.
[0009]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, the present invention will be described in detail.
First, components will be described. All components are mass%.
C is preferably as low as possible from the viewpoints of wrinkle resistance at the time of diameter reduction in the manufacturing process of the container and flange formability. According to the present invention in which Sn and B are added in combination, the effect of improving the earring by reducing C to 0.01% or less is small, and there is also an increase in cost due to the application of vacuum degassing, etc. It is preferable to be 0.015% or more. Further, the upper limit is limited to 0.06% or less at which the effect of the combined addition of Sn and B is remarkably obtained.
[0010]
Sn and B are contained as essential elements in the present invention.
If Sn is less than 0.003, no effect is obtained, and if it exceeds 0.1, not only the effect of reducing earrings is obtained, but also deterioration of workability, cracking occurs when hot rolling is performed, product yield, The appearance is significantly impaired.
B is limited to the range of 0.0002 to 0.0030% because excessive addition not only deteriorates the workability but also raises the recrystallization temperature and restricts the annealing conditions after cold rolling.
[0011]
Although it is not clear about the mechanism in which the effect of the combined addition of Sn and B is manifested in the steel sheet with a limited amount of C, C, Sn, and B are elements that tend to segregate at the grain boundaries in the steel sheet. It is thought that it affects the deformation behavior and recrystallization behavior near the grain boundary during cold rolling and recrystallization, and develops a texture effective in reducing anisotropy.
[0012]
Si, Mn, P, S, Al, N, etc. inevitably contained in ordinary steel sheets are contained to the extent that they are generally contained in steel sheets used for processing. The ranges are Si: 0.001 to 0.5%, Mn: 0.02 to 1.0%, P: 0.002 to 0.08%, S: 0.002 to 0.05%, Al: 0 0.010 to 0.100%, N: 0.0005 to 0.0060%.
[0013]
In the present invention, the means for producing a steel sheet having a diameter of 0.4 mm or less is not particularly limited, but is generally produced through at least one cold rolling and annealing process. Usually, it is manufactured by hot rolling, cold rolling, annealing, and re-cold rolling. Slabs used for hot rolling are not limited in production methods such as the ingot method and continuous casting method, and are less affected by the heat history up to hot rolling. The effect of the present invention can also be obtained by CC-DR method in which hot rolling is performed, and also by thin slab casting in which rough rolling is omitted.
[0014]
For thin steel sheets of 0.4 mm or less, earrings become a problem particularly when the cold rolling reduction ratio is high. When passing through the cold rolling process, the cold rolling reduction in the cold rolling process after hot rolling and pickling is 70 to 98% of primary cold rolling performed after pickling and before annealing, and secondary cold rolling performed after annealing. The effect of the present invention becomes remarkable when the total cold rolling rate from the pickling plate to the final product is set to 92 to 98%. These cold-rolling rate distributions are determined in consideration of cold-rolling capacity and securing the sheet passability in the annealing process after the primary cold rolling.
In addition, according to the present invention, it is possible to generate earrings even in a hard steel sheet subjected to high secondary cold rolling of 20% or more for the purpose of setting the thickness at the time of hardness adjustment or annealing and ensuring the annealing passability. The effect of suppressing is acquired.
[0015]
Although annealing is performed after the primary cold rolling, this temperature is set to the recrystallization temperature or higher and 800 ° C. or lower, and the time is set to 3 minutes or shorter. In order to ensure the uniformity of material properties and workability, it is necessary to recrystallize the rolled structure sufficiently, and at over 800 ° C., the earring becomes small regardless of the steel type, and at the same time, the effect of the present invention is obtained. This is because the texture may disappear due to transformation. Further, in the steel of the present invention, ductility that can withstand practical use can be ensured even at a low annealing temperature at which sufficient ductility cannot be ensured with conventional steel. The temperature range where the remarkable effect different from that of the conventional steel is obtained in the steel of the present invention is 550 to 680 ° C.
[0016]
Usually, the steel sheet of the present invention is used as an original sheet for a surface-treated steel sheet, but the effect of the present invention is not impaired by the surface treatment. As the surface treatment for cans, tin, chromium (tin-free), etc. are usually applied. Moreover, it can be used, without impairing the effect of this invention, also as the negative | original plate for laminated steel plates which stuck the organic membrane which has come to be used in recent years.
[0017]
【Example】
In the evaluation of the present invention, an earring rate represented by the following formula (1) is used as an index indicating the degree of ear generation with reference to FIG. Ear generation becomes more prominent as the earring rate increases.
Earring rate = (h max−h min) / (average height of can wall) ……… (1)
[0018]
The steel of each component shown in Table 1 was hot-rolled, cold-rolled and annealed to produce a steel plate, and the earring rate was measured. The effect of adding Sn and B on the earring rate in relation to the C content is shown in FIG.
It can be seen that the earrings can be remarkably reduced by adding Sn and B in a specific range of the C amount. In Table 1, the relationship between the annealing temperature and earrings for steels a, b, and c is shown in FIG. It can be seen that the steel of the present invention has a great effect of reducing earrings particularly in the low temperature annealing region. Table 2 shows manufacturing conditions and materials for other steels. As is apparent from Table 2, good characteristics were obtained for those produced within the scope of the present invention.
[0019]
[Table 1]

[0020]
[Table 2]

[0021]
【The invention's effect】
As described above, according to the present invention, it is possible to produce a steel sheet for an ultrathin container with a small occurrence of drawn earrings that can improve the yield and productivity of steel sheets during can making at a high cold rolling rate.
[Brief description of the drawings]
FIG. 1 is a view showing the degree of occurrence of an ear of a steel plate as a relation between a cup shell wall height and a cup peripheral position.
FIG. 2 is a graph showing the effect of Sn and B addition on the earring rate in relation to the amount of C.
FIG. 3 is a diagram showing the relationship between the annealing temperature and earrings for steels a, b, and c in Table 1.

Claims (3)

In mass%,
C: 0.015-0.060%,
Si: 0.001 to 0.5%,
Mn: 0.02 to 1.0%,
P: 0.002 to 0.08%,
S: 0.002 to 0.05%,
Al: 0.010 to 0.100%,
N: 0.0005 to 0.0060%,
Sn: 0.003 to 0.100%,
B: 0.0002 to 0.0030%
A steel plate for containers which contains a balance Fe and unavoidable impurities and has a thickness of 0.4 mm or less and has a remarkably small earring during drawing. In mass%,
C: 0.015-0.060%,
Si: 0.001 to 0.5%,
Mn: 0.02 to 1.0%,
P: 0.002 to 0.08%,
S: 0.002 to 0.05%,
Al: 0.010 to 0.100%,
N: 0.0005 to 0.0060%,
Sn: 0.003 to 0.100%,
B: 0.0002 to 0.0030%
The hot rolled sheet containing the remainder Fe and inevitable impurities is cold-rolled at a reduction rate of 70 to 98%, annealed at a recrystallization temperature of 800 ° C. or less for 3 minutes or less, and a reduction rate of 0.5 Production of a steel plate for a container having a remarkably small earring at the time of drawing, characterized by re-rolling so that the total cold rolling reduction ratio from hot rolled sheet to final product is 92 to 98 %. Method. The method for producing a steel plate for a container having a remarkably small earring at the time of drawing according to claim 2 , wherein the annealing temperature is 550 to 680 ° C.

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