JPH0418018B2 - - Google Patents

Description

[Detailed description of the invention]

(Industrial Application Field) The present invention relates to an aluminum alloy plate for cans mainly used for can body materials such as beverage cans and food cans. (Prior Art) For can body materials such as beverage cans and food cans, 3004, 3104, which has excellent deep drawability, and aluminum alloys having similar chemical components are often used. Conventionally, can body materials using this aluminum alloy have been manufactured according to the manufacturing process flow shown in FIG. That is, raw materials adjusted to have the desired chemical composition are melted and cast, the ingots or slabs are faced with a circular saw, and then subjected to soaking treatment.
It is hot-rolled, then cold-rolled with intermediate annealing, and then packed into a predetermined width using a slitter. Note that there are two types of intermediate annealing: a case where a batch furnace is used and a case where a continuous furnace is used. Further, cold rolling before intermediate annealing may be omitted depending on the case, and therefore, the hot rolled material may be annealed and then cold rolled. The can body material manufactured through this process flow is then subjected to cup molding, as shown in Figure 2.
The cans undergo ironing and other can-forming processes, and after trimming, degreasing, cleaning, chemical conversion treatment, etc. are performed, and then printing is applied. Then, the inner surface is coated using a heating dryer, and after being heated and dried, it is subjected to netsker flanging or netting and flange processing, and after pinhole inspection, it is made into a product. (Problems to be Solved by the Invention) By the way, the above-mentioned molded can body can be degreased,
After cleaning, painting the inner surface, and drying, a black stripe pattern (hereinafter referred to as "black stripe") may appear on the can surface as shown in FIG. 3, which has a problem of reducing the commercial value. These black streaks are caused by the poor lubrication between the tool and the material during cup forming or ironing during the can forming process, resulting in seizure, but various countermeasures have been attempted in the past. However, no effective measures have been found. SUMMARY OF THE INVENTION An object of the present invention is to provide an aluminum alloy plate for cans that can effectively suppress the occurrence of black streaks after forming cans and has excellent black streak resistance. It is something. (Means for Solving the Problems) In order to achieve the above object, the inventors of the present invention discovered that black streaks are caused by seizure caused by deterioration of the lubrication condition during can forming process, and therefore worked to elucidate the mechanism by which the black streaks occur. However, when seizure occurs, processing stress increases, and as a result, voids are formed between the intermetallic compound and the matrix with different deformation resistance, and these voids remain even after can cleaning and printing, resulting in black streaks. It was found that this was recognized as a defect. Therefore, the inventor of the present invention has discovered that if a material is manufactured that is difficult to form voids during can forming process, and if the deformation resistance is also reduced, the black streak resistance can be improved. As a result of various experimental studies, we found that by making the aluminum alloy plate for cans have a specific chemical composition and regulating the size, analysis state, and surface condition of intermetallic compounds, the lubrication conditions during can forming processing were improved compared to conventional ones. It has been discovered that the occurrence of black streaks can be suppressed even in extremely poor conditions such as this. That is, in the present invention, Mn: 0.8 to 1.5%, Mg:
0.8~1.5%, Zn: 0.05~1.00%, Cu: 0.05~0.50
%, Fe: 0.30 to 0.80% and Si: 0.10 to 0.60%, and optionally further contains Ti: 0.05% or less, the balance being Al and impurities, the metal in the alloy The maximum size of the intermediate compounds is 20 μm or less, and 20 / 15 to 20 μm.
mm ² or less, the area ratio is 1.5 to 4.0%, the contact angle with water is 60° or less, and the surface roughness Ra is 0.10 to 0.40 μm.
The gist of this invention is an aluminum alloy plate for cans that has excellent black streak resistance and is coated with an oil-based film of mg/m ² . The present invention will be explained in detail below based on examples. As described above, the present invention improves the black streak resistance by reducing the deformation resistance during the can forming process and reducing the voids between the matrix and the intermetallic compound. First, as a means to reduce the latter void size, the compound components of the aluminum alloy plate are regulated, and the maximum size, area ratio, and distribution of the intermetallic compounds are regulated, thereby making the intermetallic compounds finer. In addition, the material is made uniformly distributed and has no difference in deformation resistance between the matrix and the intermetallic compound.
This reduces the occurrence of black streaks. Regarding the regulation of chemical components, 3004 and 3104, which have been conventionally used as aluminum can body materials, are used as base materials, but the chemical components are further regulated for the following reasons. Mn: Mn is an element necessary for improving strength, and it also forms an intermetallic compound FeMn when combined with Fe.
(Al ₆ ) is an element that can improve ironing workability through proper distribution. However, if the Mn content is less than 0.8%, the effect is small, and if it exceeds 1.5%, strong intermetallic compounds are formed and workability is inhibited, which is not preferable. Therefore, the amount of Mn is 0.8~
The range shall be 1.5%. Mg: Mg is an element necessary for improving strength, but if it is less than 0.8%, its effect will be small, and if it exceeds 1.5%, it will easily crack during hot rolling, so the amount of Mg should be 0.8 to 1.5%.
The range shall be . Zn: Zn is an element that is effective in properly dispersing crystallized substances and improving formability. But 0.05
If it is less than 1.0%, there is no effect, and if it exceeds 1.00%, a problem will arise in corrosion resistance. Therefore, the amount of Zn is
It should be in the range of 0.05-1.00%. Cu: Cu is an element necessary for improving strength, but if it is less than 0.05%, its effect will be small, and if it exceeds 0.05%, there will be problems with corrosion resistance, so the amount of Cu should be 0.05 to 0.50%.
The range shall be . Fe: Fe is an intermetallic compound formed in combination with Mn.
It is an element that contributes to improving ironing workability through proper distribution of FeMn (Al). However, if Fe is less than 0.30%, the effect is small, and if it exceeds 0.80%, strong intermetallic compounds are formed, which inhibits workability. Therefore, the amount of Fe should be in the range of 0.30 to 0.80%. Si: Si causes phase transformation of the intermetallic compound FeMn (Al ₆ ) to become an Al-Fe-Si intermetallic compound, which increases hardness and has the effect of improving ironing workability. However, if Si is less than 0.10%, it has no effect, and if it exceeds 0.60%, it causes cracking during ingot formation or hot rolling. Therefore, the amount of Si is 0.10
The range shall be ~0.60%. Note that a small amount of Ti may be added as necessary in order to refine the crystal grains of the ingot. If too much is added, the size and number of intermetallic compounds may increase, so it is preferably 0.05% or less.
0.03% or less. In general, for can body materials, the presence of intermetallic compounds having a certain size and distribution is essential during forming, especially during ironing. However, there are many intermetallic compounds over a certain size,
In addition, if the deformation resistance is large, voids are likely to be generated at the boundaries during deformation processing, which becomes a factor in the generation of black streaks. Therefore, it is necessary to regulate the amount of intermetallic compounds that have a size larger than a certain level per unit area, and in the present invention, the maximum allowable size of intermetallic compounds is set to 20 μm.
m or less, and intermetallic compounds with a size of 15 to 20 μm are
Distributed at 20 pieces/mm2 or ^less , and the area ratio is 1.5 to 4.0%
The material is manufactured so that Outside these conditions, miniaturization and uniform distribution of intermetallic compounds cannot be achieved. Furthermore, since it is determined by the casting conditions such as the distribution of intermetallic compounds, chemical composition of size, cooling conditions between liquidus line and solidus line, and homogenization treatment conditions, it can be determined by these alone or in combination. Therefore, it is possible to manufacture a material that satisfies the above requirements. Next, the former means for reducing deformation resistance can be broadly classified into measures for improving lubricity and measures for reducing material deformation resistance. In order to reduce deformation resistance by improving lubricity, the contact angle between the material and water before applying lubricant should be reduced.
It is necessary to control the angle to 60° or less and to control the amount of oily film by applying mineral oil or synthetic oil to 50 to 500 mg/m ² . Generally, during can forming processes such as cup forming and ironing, a lubricating oil made of an emulsion of mineral oil or synthetic oil is used to enhance the material forming ability, but the contact angle between the material and water before applying the oil is of
Setting the angle to 60° or less is a necessary condition so that the emulsion of lubricating oil can easily adhere to the material. The contact angle can be adjusted by using water-soluble rolling oil and degreasing the surface of the aluminum alloy plate. on the other hand,
Mineral oil or synthetic oil is mainly composed of esters, etc., with some additives added to it to improve lubricity, and is basically an undiluted solution of emulsion-type lubricating oil used for can molding. However, by applying an appropriate amount of such oil to the material in advance, even if the concentration of lubricating oil for molding is low, the lubricity of the material can be improved and the resistance to processing deformation can be reduced. can. For this purpose, apply mineral oil or synthetic oil so that the amount of film is in the range of 50 to 500 mg/m ² . If the oil is less than 50 mg/m ² , the above effects cannot be obtained, and even if the oil is applied in an amount exceeding 500 mg/m ² , the effect is saturated and becomes rather uneconomical. 50-30mg/ ^m2 is desirable. In addition, in order to reduce the material deformation resistance, it is necessary to regulate the surface roughness Ra of the material within the range of 0.10 to 0.40 μm. Outside this range, the wrinkle pressing pressure may be too high or too low, causing problems in the can forming process. It turns out. It goes without saying that the aluminum alloy plate for cans of the present invention having the above-mentioned requirements can be processed and processed after can forming in the same manner as in the past. Next, examples of the present invention will be shown. (Example) Using an aluminum alloy having the chemical components (wt%) shown in Table 1 as a can body material, the material was manufactured according to the normal manufacturing flow shown in Figure 1, and
As shown in the table, the maximum size and area ratio of the intermetallic compound, the contact angle and surface roughness of the material with water, and the amount of mineral oil film were adjusted. The distribution of intermetallic compounds with a diameter of 15 to 20 μm was 30 particles/mm ² in sample material D, and 20 particles/mm ² or less in all other sample materials. These can body materials were then subjected to cup forming and ironing under the following conditions, degreased, and then examined for black streak resistance. To evaluate the black streak resistance, we checked the occurrence rate and degree of black streaks on 20 cans that were left defatted, and if mild black streaks occurred in 5% or less (◎
), mild and moderate cases occur in 10% or less (○ mark), mild and moderate cases occur in 25% or less, or severe cases occur in 5% or less (□ mark),
Mild and moderate cases are less than 50%, or severe cases are less than 50%.
Classified and evaluated into 5 ranks: if it occurs in 15% or less (△ mark), if it occurs in 50% or more of mild and moderate cases, or if it occurs in 15% or more of severe cases (x mark), and mark it with ◎. Those marked with ○ have the best black streak resistance, followed by those marked with □ and △.
It was determined that the black streak resistance deteriorated in the order of marks and x marks. Cup forming processing conditions Lubricating oil: Quaker 800CS 10% Blank diameter: 128mmφ Material plate thickness: 0.33mm Drawing ratio (blank diameter/punch diameter): 1.75 Wrinkle pressing pressure: 4Kg/cm ² Ironing processing conditions Lubricating oil: Quaker 800DI 8% Ironing rate {(material thickness - wall thickness / material thickness) x 100}: 6
1% Degreasing conditions Liquid used: Ridrin 419 1.5% Bath temperature conditions: 80℃ x 3min

【table】

[Table] (Note) In relation to the present invention, ○ marks are within the scope of the present invention.
× indicates outside the scope of the present invention. The evaluation results of black streak resistance are as shown in Table 2 in relation to the scope of the present invention. While the generation of streaks is slight and the black streak resistance is excellent, other test materials have large black streaks in both quantity and degree, especially regarding the requirements of chemical components and the voids between intermetallic compounds. If the requirements are not met (sample material D), the black streak resistance will be poor, but even if these two requirements are met, if one of the other requirements is not met,
As expected, the black streak resistance is poor. Furthermore, the results of analyzing the above experimental data are presented in the fourth section.
Figure 4 shown in Figures 7 to 7 shows the results of examining sample materials A, D, and J for the size distribution of intermetallic compounds, and these points are within the scope of the present invention. It can be seen that both specimens A and J have a good distribution, whereas in specimen D, large-sized intermetallic compounds are distributed over a wide area.
Figure 5 summarizes the relationship between the contact angle between the material and water and the amount of cup-forming lubricant deposited for each sample material.When the contact angle exceeds 60°, the amount of cup-forming lubricant deposited decreases markedly. 40°, which meets the requirement of 60° or less
All of the test materials with contact angles from 1 to 30% below showed good adhesion. Further, FIG. 6 shows the relationship between surface roughness and wrinkle pressing pressure (breakage), and it can be seen that when the surface roughness Ra is within the range of 0.10 to 0.40 μm, sufficient wrinkle pressing pressure can be ensured. Figure 7 similarly shows the relationship between the amount of oil applied, the contact angle, the surface roughness, and the wrinkle pressing pressure. If the degree is outside the range of the present invention, a certain amount of wrinkle pressing pressure can be obtained. It can be seen that if all of these are within the range of the present invention, sufficient wrinkle suppressing pressure can be ensured. In any case, by ensuring a large value of wrinkle pressing pressure (breakage), can moldability is good and can contribute to improvement of black streak resistance. (Effects of the Invention) As detailed above, according to the present invention, the chemical composition, the size and distribution of intermetallic compounds, the surface condition of the material, and the amount of oil applied are specified for aluminum alloy plates for cans, so cup forming is possible. Even when the lubrication conditions are poor, the occurrence of black streaks can be effectively suppressed, and the black streak resistance can be significantly improved.

[Brief explanation of drawings]

Figure 1 is a diagram showing the manufacturing process flow of can body material, Figure 2 is a diagram showing the process flow of processing and processing can body material such as molding, and Figure 3 a, b, and c are diagrams showing the process flow of can body material. A diagram showing the state of black streaks that have occurred, Figure 4 is a diagram showing the distribution of intermetallic compounds by size, and Figure 5 is a diagram showing the relationship between the contact angle between the material and water and the amount of cup forming lubricating oil deposited. , Figure 6 shows the relationship between the surface roughness of the material and the wrinkle pressing pressure (breakage), and Figure 7 shows the relationship between the amount of oil applied, the contact angle between the material and water, the surface roughness, and the wrinkle pressing pressure (breaking). FIG.

Claims (1)

[Claims] 1% by weight (the same applies hereinafter), Mn: 0.8 to 1.5%,
Mg: 0.8~1.5%, Zn: 0.05~1.00%, Cu: 0.05~
0.50%, Fe: 0.30 to 0.80%, and Si: 0.10 to 0.60%, the balance being Al and impurities, the intermetallic compound in the alloy has a maximum size of 20 μm or less, and 15 ~20μm particles are distributed at less than 20 pieces/ ^mm2 , and the area ratio is 1.5
~4.0%, and the contact angle with water is 60° or less, and the surface roughness Ra is 0.10 to 0.40 μm.
An aluminum alloy plate for cans with excellent black streak resistance, characterized by being coated with an oil film of 50 to 500 mg/ ^m2 . 2 Mn: 0.8-1.5%, Mg: 0.8-1.5%, Zn:
0.05~1.00%, Cu: 0.05~0.50%, Fe: 0.30~0.80
% and Si: 0.10-0.60%, further Ti: 0.05%
An aluminum alloy plate containing the following, the balance being Al and impurities, wherein the maximum size of the intermetallic compound in the alloy is 20 μm or less, and 15 to 20 μm
20 pieces/ ^mm2 or less, the area ratio is 1.5 to 4.0%, and the contact angle with water is 60°.
An aluminum alloy plate for cans having excellent black streak resistance, characterized in that the surface of the alloy plate having a surface roughness Ra of 0.10 to 0.40 μm is coated with an oil film of 50 to 500 mg/m ² .