JP3560267B2 - Manufacturing method of polyester resin coated steel sheet for thinning deep drawn ironing can - Google Patents

Description

【００１７】
【表２】

【００１８】
【表３】

【００１９】
【表４】

【００２０】
【実施例】
（評価）本発明の実施例Ｎｏ．１〜７は、本発明の成分範囲内にあり、加工性、肌荒れ性、ストレッチャー・ストレインの発生もない。
比較例Ｎｏ．９は、ＢＡ焼鈍を行っているため、結晶粒径が８．６μｍと大きく肌荒れ性が劣っている。比較例Ｎｏ．１０は、Ａｌ量が少なく、Ｎ量が多いため固溶Ｎが多く降伏点伸びが本発明範囲を越えており、製缶後のストレッチャー・ストレインの発生が認められる。比較例Ｎｏ．１２は、Ｃ量が多く加工性が劣っている。比較例Ｎｏ．１３は、Ｃ量が少ないため結晶粒径が大きく、また降伏点伸びも大きく肌荒れ性に劣り、ストレッチャー・ストレインの発生も認められる。なお、ここで評価法はそれぞれ以下のようにした。肌荒れ性の評価は、深絞りしごき加工による製缶を行い、缶内面の缶側壁の表面粗さを測定し、Ｒａが１μｍ以下を○（良）、１μｍを越えると×（不良）として評価した。耐食性の評価は、製缶後１３０℃×２０分の熱処理を行い、水を充填し３７℃で２週間経時後の缶内面の腐食（黒化）程度を目視で評価した。表面が全く黒化していないものを○（良）とし、黒化しているものを×（不良）とした。加工性の評価は、絞りしごき加工で缶を作り、フランジの大きさを測定しフランジ長さのＭＡＸ−ＭＩＮで評価した。ＭＡＸ−ＭＩＮが２．５ｍｍ以下を○（良）、２．５ｍｍを越えるものは×（不良）として評価した。ストレッチャー・ストレインの評価は、発生の有無で評価した。
【００２１】
【発明の効果】
本発明の製造方法により加工性、肌荒れ性、耐食性に優れ、しかもストレッチャー・ストレインの発生がない薄肉化深絞りしごき缶用途に適したポリエステル樹脂被覆鋼板を提供することができる。[0001]
[Industrial applications]
The present invention relates to a method for producing a container material mainly used for carbonated drinks, coffee / tea drinks, fruit drink cans, etc., and is excellent in suppressing the occurrence of stretcher strains at the bottom of the can, and is excellent in rough skin resistance and corrosion resistance. And a method for producing a steel sheet suitable for use in a deep-drawing thinned can.
[0002]
[Prior art]
Conventionally, as a method of forming a side seamless can, there is a DI (Draw and Ironing) method in which an organic paint is applied to the inner and outer surfaces of a can after forming a surface-treated steel sheet. Further, there is a molding method (Draw Thinning Draw) in which a metal film before molding is coated with a resin film in advance, the resin film is used as a kind of molding lubricant, and the metal plate in a portion serving as a can side wall is thinned only by drawing. . Further, there is a molding method disclosed in Japanese Patent Application Laid-Open No. 6-313223 in which ironing is combined with drawing. In the molding method disclosed in JP-A-6-313223, the number of deep drawing steps is smaller than in the conventional forming method using only deep drawing and redrawing, so that the influence of the crystal grain size is reduced. Skin roughness is reduced.
[0003]
[Problems to be solved by the invention]
In the DI molding method, after the surface-treated steel sheet is made into a can body, the dome is formed by overhanging the bottom of the can, and then an organic paint is applied and baked at a temperature of about 210 ° C. Letcher strain is not a problem. However, in the case of the thinning deep drawing method or the deep drawing ironing method, a steel sheet coated with a polyester resin by heating a surface-treated steel sheet to about 200 to 280 ° C. is used. Because of the aging phenomenon, yield point elongation occurs. When this steel sheet is made into a can body, if the dome is formed at the bottom of the can, a stretcher strain is generated at the bottom of the can, and cracks occur in the polyester resin at the bottom of the can, resulting in deterioration of corrosion resistance. In addition, the appearance of the display is impaired.
[0004]
Low carbon aluminum killed steel is used for the steel sheets provided for these, but when manufactured by continuous annealing, most of C and N in the steel exist in a solid solution state due to rapid heating and short annealing. In the case where the organic paint is baked before can-making, a stretcher strain due to elongation at the yield point occurs after molding, and the appearance is impaired. At present, an annealing method in which the yield point elongation is suppressed by performing rapid aging treatment by continuous annealing is known. However, in this method, although the dissolved C is reduced by the overaging treatment, the N does not precipitate as a nitride by the overaging treatment but remains in a solid solution state. It cannot be suppressed. Therefore, the product has a large variation in yield point elongation and is inferior in uniformity of product characteristics. In order to carry out the overaging treatment, quenching zone and overaging zone equipment are required in addition to a normal continuous annealing furnace. Therefore, compared to continuous annealing equipment having no overage equipment, the equipment becomes larger and causes a rise in construction cost. Further, the overaging treatment causes a large consumption of combustion gas, which causes an increase in manufacturing cost. Rapid cooling is required to leave solid solution C before overaging treatment. However, due to rapid temperature change in the quenching zone, the shape of the plate during the passing changes, and a meandering phenomenon appears in the passing. It becomes necessary to reduce the passing speed. Further, defects such as a cooling buckle are generated, which causes a reduction in yield and impairs high-speed sheet passing property. An object of the present invention is to provide a method for producing a polyester resin-coated steel sheet for deep-drawing and ironing cans having a reduced thickness by a method without overaging treatment in a continuous annealing step for the purpose of preventing a decrease in productivity as described above. Furthermore, the present invention provides a method for producing a polyester resin-coated steel sheet which is excellent in workability, skin roughness, corrosion resistance, prevents the occurrence of stretcher strain and is excellent in uniformity of material and suitable for deep drawing ironing cans. Things.
[0005]
[Means for solving the problem]
The present invention relates to a method for producing a polyester resin-coated steel sheet for a thin-walled deep drawn can. The method for producing a steel sheet that suppresses the occurrence of stretcher strain and is suitable for rough surface resistance and corrosion resistance is as follows: 06%, Si ≦ 0.05%, Mn ≦ 0.9%, P ≦ 0.04%, S ≦ 0.04%, Al: 0.04-0.12%, N: 0.0015-0. A hot-rolled steel sheet consisting of 0050%, the balance Fe and inevitable impurities other than the above , is sequentially cold-rolled, continuously annealed, temper-rolled, subjected to surface treatment after temper-rolling, and has a grain size of 8 μm or less. The original plate is coated with a polyester resin to reduce the elongation at yield to 5% or less .
C: 0.008 to 0.06%, Si ≦ 0.05%, Mn ≦ 0.9%, P ≦ 0.04%, S ≦ 0.04%, Al: 0.04 to 0.12 %, N: 0.0015 to 0.0050%, B : 0.0005 to 0.005%, hot rolled steel sheet composed of the balance Fe and inevitable impurities other than the above , sequentially cold-rolled, continuously annealed, and tempered. Temper rolling and temper rolling surface treatment to form a base plate having a crystal grain size of 8 μm or less, and coating the base plate with a polyester resin to reduce the yield point elongation to 5% or less .
[0006]
BEST MODE FOR CARRYING OUT THE INVENTION
The original plate according to the present invention is coated with a polyester resin film , punched into a disc shape, and subjected to a composite continuous high-speed can-making process combining a two-stage drawing and ironing process. -It is possible to form a thin-walled deep-drawing can that is free of strain and has excellent surface roughness and corrosion resistance.
[0007]
(Composition of hot rolled steel sheet)
The steel component according to claim 1 includes: C: 0.008 to 0.06%, Si ≦ 0.05%, Mn ≦ 0.9%, P ≦ 0.04%, S ≦ 0.04%, Al : 0.04 to 0.12%, N: 0.0015 to 0.0050%, the balance being Fe and inevitable impurities other than the above.
The steel component according to claim 2 is: C: 0.008 to 0.06 %, Si ≦ 0.05%, Mn ≦ 0.9%, P ≦ 0.04%, S ≦ 0.04%, Al : 0.04 to 0.12%, N: 0.0015 to 0.0050%, B : 0.0005 to 0.005%, balance Fe and inevitable impurities. The reasons for regulating steel components are described below. If C is less than 0.008%, yield point elongation occurs during lamination, so the lower limit was made 0.008%. On the other hand, if it exceeds 0.06%, the formability deteriorates due to heat generated during drawing and ironing, so the C content range is set to 0.008 to 0.06%. Si is an element harmful to corrosion resistance as a material for cans, but is an element inevitably contained in Al-killed steel, and the upper limit is 0.05%. Mn is a component necessary for preventing red hot embrittlement during hot rolling due to S as an impurity. On the other hand, if it exceeds 0.9%, drawability deteriorates, so the upper limit is set to 0.9%. did. P is an effective component for refining crystal grains, and is added at a certain ratio to increase the strength of the original plate, but impairs corrosion resistance. For the steel sheet for cans of the present invention, if P exceeds 0.04%, the corrosion resistance, particularly the puncture resistance, is significantly reduced, so the upper limit was made 0.04%. S is an impurity component that causes red hot embrittlement during hot rolling, and is desirably as small as possible. However, S is an element inevitably contained, and the upper limit is set to 0.04%. Al is added to the steel bath as a deoxidizing agent during steelmaking and is removed as slag. However, if the amount is small, a stable deoxidizing effect cannot be obtained. Al fixes N in steel as AlN, and is useful for a yield point elongation reduction effect after lamination. However, if the content is less than 0.04%, the effect of reducing the yield point elongation cannot be obtained, and if the content exceeds 0.12%, the technical effect is small, and it is not economically preferable. It was 12%. N forms a nitride with Al and B, and is an effective component for grain refinement of the crystal grains. However, if it is less than 0.0015% , precipitation of the nitride is small, and the effect of the grain refinement is lost. On the other hand, excessive addition of N results in an increase in solid solution N due to the effect of grain refinement of the crystal grains due to the precipitation of nitride, and causes an increase in yield point elongation. did. B is a component that forms a BN nitride similarly to Al and is useful for reducing solid solution N. B is more likely to form nitride than Al, and is precipitated as BN in the hot rolling step. However, if the amount of B is less than 0.005%, the amount of precipitated BN becomes small, so that N cannot be completely fixed. Further, the addition of excessive B strengthens the solid solution to harden the material. Further, the anisotropy deteriorates, so the upper limit is made 0.005%.
[0008]
Although the slab heating temperature and the hot rolling conditions are not specified in the present invention, if the slab heating temperature is lower than 1100 ° C., the hot rollability deteriorates, and from the viewpoint of securing the hot rolling temperature, 1100 is also used. Desirably higher than ℃. If the slab heating temperature is too high, the decomposition and re-solid solution of the nitride are promoted. If the hot rolling finishing temperature is lower than Ar3 point, the crystal structure of the hot rolled sheet is mixed and coarsened, and the deep drawability is deteriorated. Therefore, the hot rolling finishing temperature is higher than Ar3 point. The lower limit of the winding temperature is 550 ° C. in consideration of the quality stability in the coil width direction and the longitudinal direction at the time of hot rolling. If it exceeds 650 ° C., the descaling property becomes poor, and the crystal grains become coarse and the surface becomes rough. Therefore, the winding temperature is desirably in the range of 550 to 650 ° C.
[0009]
(Cold rolling step) If the rolling reduction is less than 75%, the annealing step causes coarsening or mixing of the crystal grains of the steel sheet and the crystal grains cannot be sufficiently refined. It is desirable that the lower limit be 75%.
[0010]
(Continuous annealing step) Continuous annealing requires an annealing temperature equal to or higher than the recrystallization temperature. However, if the annealing temperature is too high, the crystal grains become coarse and the surface roughness after processing becomes large. It is desirable.
[0011]
(Temperature Rolling) In temper rolling (SR, abbreviation for Single Reduce Rolling), if the elongation is in the range of 0.5 to 2.0%, the occurrence of stretcher strain is prevented. Is appropriate. In the temper rolling step, the surface roughness of the original sheet is also provided, but in the case of laminated steel sheet, the surface roughness of the original sheet is also important. If the surface roughness is too rough, the film adhesion after processing is poor, and the corrosion resistance is low. It is preferable that the surface roughness is as small as possible, and that the surface roughness does not exceed 0.5 μm.
[0012]
Next, examples of the steel sheet used in the present invention include sheet-like and coil-like steel sheets, steel foils, and those obtained by subjecting these steel sheets to surface treatment. Further, a tin-plated steel sheet, a nickel-plated steel sheet, a galvanized steel sheet, a steel sheet subjected to a surface treatment such as electrolytic chromic acid treatment, and the like are also included. In particular, as the surface-treated steel sheet suitably used as the resin-coated steel sheet, an electrolytic chromic acid-treated steel sheet having a two-layer structure of chromium metal in the lower layer and hydrated chromium oxide in the upper layer is desirable.
[0013]
The resin film used in the present invention may be a single layer or two or more layers mainly composed of a polyester resin such as polyethylene terephthalate and polybutylene terephthalate. Preferably, the thickness of the resin is 5 to 50 μm, and a polyester resin having a melting point of 180 to 260 ° C. is more preferable. The resin film may be coated in advance with an adhesive mainly composed of an epoxy resin or the like.
[0014]
(Average crystal grain size) The average crystal grain size is specified by manufacturing a laminated steel sheet from a material having the steel chemical components shown in Table 1 by the manufacturing method shown in the present invention, and roughening the surface with a deep-drawn and ironed can. The sex was evaluated. If the average crystal grain size is 8 μm or less, the surface roughness is in a favorable range, and the average crystal grain size does not exceed 8 μm.
[0015]
(Elongation at yield point) The most important factor in the present invention is the elongation at yield point. That is, the occurrence of stretcher strain after can-making is related to the yield point elongation of the laminated steel sheet. The present inventor manufactured a laminated steel sheet using the materials of the steel chemical components shown in Table 2, performed deep drawing and ironing, performed doming on the bottom of the can, and examined the occurrence of stretcher strain on the bottom of the can. The presence or absence was checked. As a result, when the yield point elongation exceeds 5%, occurrence of strainer strain is recognized, so that the yield point elongation of the resin-coated steel sheet of the present invention does not exceed 5%.
[0016]
[Table 1]

[0017]
[Table 2]

[0018]
[Table 3]

[0019]
[Table 4]

[0020]
【Example】
(Evaluation) Nos. 1 to 7 are within the range of the components of the present invention, and have no workability, rough skin, and no occurrence of stretcher strain.
Comparative Example No. In No. 9, since the BA annealing was performed, the crystal grain size was as large as 8.6 μm and the surface roughness was poor. Comparative Example No. In No. 10, since the amount of Al was small and the amount of N was large, solute N was large and the yield point elongation exceeded the range of the present invention, and the occurrence of stretcher strain after can-making was recognized. Comparative Example No. No. 12 has a large C content and is inferior in workability. Comparative Example No. No. 13 has a large crystal grain size due to a small amount of C, has a large yield point elongation, is inferior in skin roughness, and generation of a stretcher strain is also recognized. The evaluation methods were as follows. The evaluation of skin roughness was performed by deep drawing and ironing, and the surface roughness of the can side wall on the inner surface of the can was measured. . The corrosion resistance was evaluated by performing a heat treatment at 130 ° C. for 20 minutes after the can was made, filling with water, and visually estimating the degree of corrosion (blackening) of the inner surface of the can after elapse of 2 weeks at 37 ° C. If the surface was not blackened at all, it was evaluated as ○ (good), and if it was blackened, it was evaluated as x (poor). The workability was evaluated by drawing and ironing a can, measuring the size of the flange, and evaluating the MAX-MIN of the flange length. A MAX-MIN of 2.5 mm or less was evaluated as ○ (good), and a MAX-MIN exceeding 2.5 mm was evaluated as x (poor). The evaluation of the stretcher strain was evaluated based on the presence or absence of occurrence.
[0021]
【The invention's effect】
According to the production method of the present invention , a polyester resin-coated steel sheet which is excellent in workability, skin roughness, corrosion resistance, and which is suitable for use in a thin-walled deep drawn iron can that does not generate a stretcher strain can be provided.

Claims (2)

C: 0.008 to 0.06%, Si ≦ 0.05%, Mn ≦ 0.9%, P ≦ 0.04%, S ≦ 0.04%, Al: 0.04 to 0.12%, N: 0.0015 to 0.0050%, a hot-rolled steel sheet consisting of the balance Fe and inevitable impurities other than the above is subjected to cold rolling, continuous annealing, temper rolling, and surface treatment after temper rolling. A method for producing a polyester resin-coated steel sheet for deep-drawing ironing cans, characterized in that an original sheet having a crystal grain size of 8 μm or less is formed and the original sheet is coated with a polyester resin so that the yield point elongation is 5% or less . C: 0.008 to 0.06%, Si ≦ 0.05%, Mn ≦ 0.9%, P ≦ 0.04%, S ≦ 0.04%, Al: 0.04 to 0.12%, N: 0.0015 to 0.0050%, B : 0.0005 to 0.005%, hot rolled steel sheet consisting of the balance Fe and inevitable impurities other than the above , sequentially cold-rolled, continuously annealed, and temper-rolled After the temper rolling, a surface treatment is performed to form a base plate having a crystal grain size of 8 μm or less, and the base plate is coated with a polyester resin to reduce the yield point elongation to 5% or less. A method for producing a polyester resin-coated steel sheet for ironing cans.