JPS63145758A - Production of al alloy sheet for packaging - Google Patents

Abstract

PURPOSE:To produce an Al alloy sheet having excellent deep drawing and redrawing properties, by subjecting an ingot of the Al alloy contg. Mg, Mn and other alloy elements to a soaking treatment then to hot rolling and intermediate annealing followed by finish cold rolling at a specific reduction ratio. CONSTITUTION:The ingot of the Al alloy which contains, by weight %, 1-6% Mg and 0.1-2% Mn as essential components, contains <=0.4% in total 1 or 2 kinds of Cr and Fe, or further satisfies additionally one or both of the two conditions to contain 0.02-0.2% Ti and 0.0001-0.03% B or to contain 1 or 2 kinds of 0.2-1.0% Si and 0.2-2.5% Cu as essential components is subjected to the soaking treatment at >=480 deg.C and is then hot rolled to 2-6mm thickness. The steel is then subjected to cold rolling and intermediate annealing at 300-600 deg.C at need then to finish cold rolling to about 0.3mm thickness at 30-80% reduction ratio. The Al alloy sheet for packaging in which the occupying area rate of the intermetallic compd. in >=0.5mum dimensional range viewed from the surface of the rolled sheet is 3.5% and which has the excellent deep drawing and redrawing properties is produced.

Description

Detailed Description of the Invention [Industrial Field of Application] The present invention is directed to the production of an Al alloy plate with excellent deep drawability and re-rippability, which is applied to packaging such as cans, caps, and boxes/containers. It is about the method.

[Conventional technology] The quality characteristics required for packaging aluminum alloy plates are as follows: (1) High strength; (2) Good drawing workability, (3) less occurrence of ears; (4) No skin irritation occurs; (5) Good corrosion resistance; etc.

Conventionally, JIS standard Al100°A has been used for this type of application.
3003, ^3105. ASO52, A^5:152
, A3004, AA5042, A5182°, and many other Al alloys are used.

[Problems to be Solved by the Invention] However, the above-mentioned Al alloys have the following drawbacks when used as packaging materials.

Al100: High ear rate and large variation,
Furthermore, the strength is insufficient. In particular, when painting or printing is applied after molding, a baking process is usually performed at a temperature of about 180 to 200°C, but the strength decreases significantly during this process, and when sealing under gas pressure, such as with carbonated drinks, the pressure resistance is becomes a problem.

A3003: Due to the large crystal grain size, it tends to cause rough skin and has problems in appearance.

A3004, ^3105. A3052. A^5042
゜A3182. A^5352: All of them have a reasonable strength, have a low incidence of ears, and have good drawing workability, but the total drawing rate is 60-70% after deep drawing 2 to 3 times. In some cases, cracks may occur due to machining. Furthermore, if even higher strength is required, it may be possible to increase the cold working rate to promote work hardening, or to increase the amount of Mg, which is a strength-improving element. Not only this, but also the drawability deteriorates rapidly, and in the latter method, even a slight increase in the amount of Mg causes a marked drop in the drawability.

Under these circumstances, the present invention solves the above-mentioned drawbacks of conventional packaging aluminum alloys, and provides a method for producing aluminum alloy sheets that have particularly high strength and excellent deep drawability and redrawability. This is what we are trying to provide. .

[Means for solving the problems] The method for manufacturing an Al alloy plate for packaging according to the present invention consists of four inventions, and the gist of the 'TS1 invention is that Mg: 1
~6% (the meaning of weight % and the composition components are the same below)
and Mn: 0. ．． A containing 1 to 2% as an essential component, and 0.4% or less of Fe and Cr, preferably both, as a total, with the remainder being Al and impurities.
The l alloy is melted and cast, soaked at a temperature of 480°C or higher, then hot rolled, then subjected to intermediate annealing at 300 to 600°C with or without cold rolling, and further processed at a working rate of 30 to 600°C. Finish cold rolling is performed at 80%, and the area occupation rate of intermetallic compounds having a size range of 0.5 μm or more as seen from the temporary rolling surface is suppressed to 3.5% or less. The second to fourth inventions are (a) 0.
02-0.2% Ti and 0.0001-0.3% B
The condition that it contains as an essential component and (b) 0.2
In addition, one or both of the two conditions of containing one or two alloying elements selected from the group consisting of ~1% Si and 0.2-2.5% Cu This is a summary.

[Function] Hereinafter, the reasons for determining the chemical composition and processing conditions of the Al alloy will be explained, and the respective functions will be clarified.

First, in the present invention, 1 to 6% of Mg and 0.6% of Mg are used as alloying elements.
An Al alloy containing 1 to 2% Mn and one or both of Fe and Cr in a total of 0.4% by weight or less is used, and the reason for specifying these chemical components is as follows. It is.

Mg: 1-6% Mg is an indispensable element because it is essential for providing sufficient strength to the Al alloy plate, and must be contained in an amount of 1% or more in order to achieve the purpose. However, if it is too large, the rollability and formability will deteriorate, so it is necessary to keep it to 6% or less. A more preferable Mg content is 2 to 6%.

Mn: 0.1-2% Like Mg, it is an essential component for increasing mechanical strength, and especially when the amount of Mg is large, it improves the ground rolling ability to suppress the strength loss after baking coating compared to Mg alone. It has an enhancing effect. These effects are effectively exhibited by containing 0.1% or more, but on the other hand, if the content exceeds 5%, Ala (Mn, Fe
) and 6.16Mn, etc., which tend to cause cracks during drawing, so it must be kept at 2% or less. A more preferable Mn content is 0.3 to
The range is 1.5%.

CF e 10Cr): 0.4% or less Fe and Cr
Although the degree differs depending on the amount of Mn,
, Al2Cr7 s Ale (Mn, Fe) or Al
2 (Cr, Fe) etc. are generated, which significantly increases cracking susceptibility during drawing.To avoid this problem, the total amount of Fe and Cr must be kept below 0.4%. No. Particularly when deep drawing is performed two to three times and the total drawing ratio reaches 60 to 70%, ffi is extremely important. When ironing is applied to body materials for beverage cans, the intermetallic compound formed by Fe exhibits a lubricating effect, so it may be actively included depending on the application. In the alloy produced by this method, the content is limited to 0.4% or less for the reasons mentioned above in order to improve drawability and redrawability. Corrosion resistance is also improved as another effect of suppressing the content of Fe and Cr to a low level.

The essential elements of the alloy used in the present invention are as follows,
The remaining Qi (components are Al and unavoidable impurities, but if necessary, it is also effective to further improve the performance by adding the following elements.

Si: 0.2-1%, Cu: 0.2-2.5% In most cases, conventional Al-Mg-Mn alloys contain a small amount of Si.
The physical properties can be further improved by actively adding Cu. That is, Si has the effect of increasing drawability, and this effect is effectively exhibited by containing it in an amount of 0.2% or more. However, the effect reaches saturation at about 1%, so adding more than that is completely meaningless.

In addition, Cu has the function of increasing the mechanical strength and drawability of the alloy, and also has the effect of forming a solid solution with Mg during solution treatment and producing fine Al-Cu-Mg-based precipitates during baking, resulting in hardening. These effects can be effectively exhibited by containing 0.2% or more. However, if it is too large, the rolling properties and corrosion resistance will deteriorate, so it must be kept at 2.5% or less.

Ti: 0.02-0.2%, B:
Both 0.0001 to 0.03% Ti and B not only refine the crystal structure of the alloy, but also refine the cell structure and improve drawability. By containing 0.0001% or more, the effect becomes more apparent. However, these effects are 0.2
%, and B reaches a saturation state at about 0.03%, and adding more than that is wasteful.

The alloy plate manufactured by the method of the present invention is the above-mentioned Al-M
It is obtained by hot and cold rolling after melting and casting a g-Mn alloy, but the characteristics required for the final sheet material are ``intermetallic compounds with a size range of 0.5 μm or more as seen from the temporary rolling surface.'' The requirement that the area occupancy rate of the area is 3.5% or less is mandatory. In other words, the present inventors have compiled a large amount of experimental data and found that the cause of cracks that occur during drawing is the presence of large grains among the various intermetallic compounds mentioned above, and in particular, the presence of large grains on the temporary rolling surface. It was confirmed that intermetallic compounds exist in the presence of large grains, and that if the intermetallic compounds are coarse and contained in large quantities, cracks are likely to occur in the grain. If the large amount of intermetallic compounds is less than 0.5 μm, it will not become a starting point for cracking, and even if there is a large loss of 0.5 μm or more, the area occupation rate of the intermetallic compounds is 3.5% or less. It was confirmed that a high level of drawability can be achieved without causing cracks or the like. The area occupancy rate of intermetallic compounds refers to the total area occupied by each of the above-mentioned intermetallic compounds in the Al matrix. Then, determine the area ratio of the crystallized material to the entire field of view. This method also allows us to easily know the distribution of particle size and number.

Next, processing and processing conditions for obtaining an alloy plate having the above-mentioned required characteristics will be explained in order of process.

(1) Melting/casting conditions First, the casting temperature is preferably in the range of 670 to 750°C.A high temperature is preferable in order to refine the crystallized substances in the ingot and improve deep drawability, but the above-mentioned A, 1-Mg In the present invention, which targets -Mn alloys, if the casting temperature exceeds 750°C, there is a risk of leakage. On the other hand, if the temperature is too low, not only will the molten alloy solidify in the gutter during casting and the yield will decrease, but also giant intermetallic compounds will form as primary crystals, which can significantly impede deep drawability. The cooling rate at the time of casting is usually set at 1 to b, although it is natural that a faster cooling rate is preferable in order to make the crystallized substances finer.

(1) Soaking conditions Soaking must be carried out at a temperature of 480°C or higher.

That is, if the temperature is lower than 480°C, a large amount of extremely fine precipitates of Al6Mn are generated, suppressing the formation of grain boundaries at the time of recrystallization of the rolled plate, and not only increasing the recrystallization temperature but also coarsening the crystal grains after recrystallization. Furthermore, as the texture of the paddy changes after recrystallization ('2), 45 degree edges to the rolling direction are likely to occur in the drawing process. It is essential to adopt a soaking temperature of 480°C or higher.Although the upper limit of the soaking temperature varies depending on the amount of Mg, it is recommended to set it below 590 to avoid local dissolution of Mg due to burning. It is best to keep it to

Further, the preferable soaking time may be appropriately determined depending on the soaking temperature, and is generally selected from the range of 1 to 24 hours.

- (Ill) The hot rolling end temperature is preferably 250°C or higher; if it is lower than 250°C, there is a tendency for a large amount of directional properties to occur. In addition, the thinner the hot-rolled plate thickness is, the better in order to reduce the directionality, but if it is too thin, the strength will be insufficient, so the best thickness is about 2 to 6 II 1 m.

(IV) Intermediate annealing This intermediate annealing is performed by applying the above-mentioned hot rolling as it is or after further applying appropriate cold rolling, forming a texture by recrystallization and reducing the deep drawing edges, as well as making the crystal grains finer and This is an essential process for uniformity, and it does not matter whether batch annealing or continuous annealing is used, but the temperature must be selected from the range of 300 to 600°C, as recrystallization will not occur below 300°C. On the other hand, if the temperature exceeds 600°C, recrystallized grains will grow too much, causing wrinkles and the like.

From the viewpoint of improving the drawability and controlling the directionality, it is preferable to perform rapid heating and rapid cooling by continuous annealing.

(V) Finish cold rolling In order to reduce the directionality and properly control the strength, the processing rate should be set in the range of 30 to 80%.
If it is less than 80%, sufficient strength will not be obtained, and if it exceeds 80%, problems will arise with directionality and deep drawability.

The processing and processing conditions adopted in the present invention have been explained above, but among these steps, (I+) to (V) are particularly important.
In the present invention, the conditions for carrying out these steps are strictly defined.

[Example] Example 1 A molten alloy having the chemical components shown in Table 1 (Si, Cu, and Ti are all impurities) was used by continuous casting method (casting temperature r! 1710°C, cooling rate 2 to b seconds) ) by J Risa55
A mm ingot was produced. After soaking at 590°C for 6 hours (6 hours at 510°C for Nos., 9, and 10), hot rolling was carried out at a finishing temperature of 300°C to a final thickness of 4 cm, and further cooled to a thickness of 0.75 mm. It was rolled for a while. then 51
5℃ (However, No. 11 to 14 are 370℃ x 2 hours, 40
°C/Hr! Intermediate annealing (using a continuous annealing furnace...holding time: 0 seconds; rapid heating and rapid cooling at 00°C/min) at 0.3 mm, followed by cold rolling (processing) to a thickness of 0.3 mm. Rate 60% (However, No. 12 is 55%, No. 13 is 5.
0%)) When we examined the mechanical properties of each of the obtained alloy plates as cold-rolled and after heat treatment at 200°C for 20 minutes (corresponding to normal paint baking conditions), we found that
The results shown in the table were obtained.

Further, each alloy plate was subjected to the following deep drawing test after being heat-treated at 200° C. for 20 minutes, and the selvage ratio (drawing ratio: 42) was also measured.

Furthermore, the area occupancy of intermetallic compounds on the surface of each plate was determined using a particle planner, and the results are also shown in Table 2.

In Table 2, the column "Crack occurrence during drawing" shows the number of times the test was conducted three times and no cracks occurred (indicated by O in the table), and the number of times cracks occurred (indicated by x in the table). Therefore, for example, "OOX" indicates that two out of three times the drawing process was successful without any cracks, and one time a crack occurred (hereinafter referred to as Section 4.6). , 8, 10.
and Table 12).

Deep drawing test method> Test plate: plate thickness 0.3+nm, 60% cold worked plate (2
(After heating at 00℃ x 20 minutes) Drawing process blank diameter (83,:l+nmφ) - 1st drawing (50mmφ: 40%) - 2nd drawing (40mmφ: 20%) → 3rd drawing (in Xmm) Wrinkle presser: 1 Next drawing...1000kg Secondary drawing...Average value of the value at which wrinkles occur (minimum value) and the value at which squeezing becomes impossible (maximum value)Third drawing...Value that can be squeezed without problems by changing the wrinkle presserLubrication Oil: Johnson Wax #700 (Johnson Company i!i), 50% aqueous solution (hereinafter referred to as "margin") As is clear from Tables 1 and 2, alloy plate (No. 1.2, 7.9°11.14,1
5.17 and 18) had an area ratio of intermetallic compounds in the size range of 0.5 μm or more of 3.5% or less, and had excellent deep drawability and redrawability when compared with the comparative materials. No,
3 to 5 are Fe, No, 10 are Mg, and No, 12
and No. 13 both have too much Cr, and No. and No. 16 have F
This indicates that e+Cr is too large. No. 6 was a comparative material, and although it had excellent deep drawability and redrawability, its strength was too low. Further, No. F3 had too high strength and had problems in deep drawability and redrawability. Furthermore, the listening rate was also high.

Example 2 Chemical components shown in Table 3 (with the exception of Ti and less than 0.2% S)
A semi-continuous casting method was used (casting temperature: 720 t, cooling rate: 2-b) using an alloy molten metal (i and Cu are impurities).Next, after soaking at 510°C for 4 hours, the final plate thickness was 2.5 at a final temperature of 300°C. Hot rolled to mm and further 0
．． It was cold rolled to a thickness of 75 mm. Then intermediate annealing at 515℃ (continuous annealing furnace used...holding time 0 seconds, 700℃/
(rapid heating/quick cooling in minutes) to further reduce the thickness to 0.3
It was cold-rolled (processing rate: 60%) to a thickness of 60%.

Mechanical properties of each obtained alloy plate as cold rolled and 2
The mechanical properties after the heat treatment at 00° C. for 20 minutes were measured, and the deep drawing test and area occupation rate of the intermetallic compound were measured in the same manner as in Example 1, and the results shown in Table 4 were obtained.

As is clear from Tables 3 and 4 of Table 3, the alloy plates (No. 19.20 and 22 to 24) that meet the specified requirements of the present invention have higher strength than comparative materials or conventional materials. Nevertheless,
It showed better deep drawability and redrawability. In addition, compared to No. 17 (Tables 1 and 3), in which the content of St and Cu is at the level of impurities, the above-mentioned one in which St and Cu are actively added within the limit amount is more effective. It showed excellent deep drawability and redrawability. Especially No. 22 and 23
had high strength during baking and excellent deep drawability and redrawability. On the other hand, those to which Si or Cu was added excessively (No. 21 or 25) had poor deep drawability and redrawability.

Example 3 A molten alloy having the chemical components shown in Table 5 (Si and Cu are impurities) was used to produce a 50 mm ingot using a mold casting method (temperature 700°C, cooling rate 2-b). After soaking for 6 hours, it was hot rolled to a final thickness of 31 at a final temperature of 300°C, and further cold rolled to a thickness of 0.75a+a+.

Thereafter, intermediate annealing (using a continuous annealing furnace...holding time: 0 seconds), rapid heating and rapid cooling at 00°C/min), followed by cold rolling (processing rate 50-60) in the same manner as in Example 1. %)
and investigated mechanical sex trafficking.

Further, in the same manner as in Example 1, the drawing test and the area occupation rate of the intermetallic compound were determined.

The results are shown in Table 6.

As is clear from Tables 5 and 6, N added with Ti and B
Alloys No. 0, 27.29 and 30 had even fewer cracks during drawing than alloy No. 28 to which Ti and B were not added, making the effect of the addition of Ti and B clear.

Example 4 An alloy plate was manufactured in the same process as in Example 2 using a molten alloy having the chemical components shown in Table 7.

Mechanical properties and Z of each obtained alloy plate as cold rolled
Mechanical properties were measured after heat treatment at oo°C for 20 minutes, and the deep drawing test and area occupation rate of intermetallic compounds were measured in the same manner as in Example 1, and the results shown in Table 8 were obtained.

Table 7 As is clear from Tables 7 and 8, the invention alloys No. 31°, 32 and 33 were mixed with No. 18.21 of Example 2, respectively.
When compared with alloys 2 and 22, the effect of adding Ti and B was clearly seen.

Example 5 A molten alloy having the chemical components shown in Table 9 (Si and Ti are impurities) was used to produce an ingot using a semi-continuous casting method (casting temperature 710°C, cooling rate 2~b 50II11). .

After soaking for 6 hours at 3 levels of 480°C and 450°C, it was hot rolled to a final thickness of 3III11 at finishing temperatures of 300°C, 270°C and 230°C, and further cold rolled to a thickness of 0.75mm. After that, intermediate annealing was performed at 360 tons (held for 2 hours, temperature raised and lowered at 40°C/Hr), and the thickness was further increased to 0.3 m.
It was cold rolled to a+ (processing rate 60%).

Mechanical properties of each obtained alloy plate as cold rolled and 2
The mechanical properties after heat treatment at 00° C. for 20 minutes were examined, and the results shown in Table 10 were obtained. Further, in the same manner as in Example 1, the drawability, selvage ratio, etc. were determined.

As is clear from Table 9 and Table 1O, when the soaking condition was 450°C for 6 hours, both the drawability and re-drawability were poor, and the selvage rate was high. In addition, among those soaked at 480° C. and 510° C., the higher the hot rolling end temperature, the better the deep drawability and redrawability were, and the lower the selvage ratio.

Example 6 A molten alloy having the chemical components shown in Table 11 (St and Ti are impurities) was used to produce an ingot using a semi-continuous casting method (casting temperature 710°C, cooling rate 2-b 600a+m). After soaking for 4 hours, the final temperature was 320℃, and the final plate thickness was 3+.
After hot rolling to a thickness of 48 m and cold rolling to a predetermined thickness,
Intermediate firing at 0℃ #i@ (continuous heating furnace used...holding time 0
(temperature raising/lowering at 900°C/min) and then cold-rolled to a thickness of 0.3 mm (processing rate 20, 40°) 0 and 90%).
A material without intermediate annealing was also added as a comparison material.

When the mechanical properties of each alloy plate obtained were investigated, the 12th
The results shown in the table were obtained. In addition, similar to each of the above Examples, the drawability and the selvage rate were determined.

As can be seen from Table 11 and Table 12, the edge ratio of the cold working ratio of 20% is in the direction of 0° to 90° with respect to the rolling direction.
The moldability was not good. In addition, those with a cold working ratio of 90% and no intermediate annealing had too high strength and poor formability.

In addition, the selvage rate was high, making it unsuitable for deep drawing. On the other hand, samples with a cold working rate of 40% and 70% gave good results in terms of formability, edge ratio, and deep drawability.

[Effects of the Invention] The present invention is configured as described above, but the key point is to specify the types and contents of the constituent elements and to suppress the area occupation rate of intermetallic compounds as seen from the rolling temporary surface to a low level. ,
It has become possible to manufacture an Al-Mg-Mn-based packaging alloy sheet with excellent strength and deep drawing workability with good reproducibility by employing the heat treatment conditions, rolling conditions, etc. specified in the present invention.

Claims (4)

[Claims] (1) Mg: 1-6% by weight and Mn: 0.1-2% by weight
An Al alloy containing 0.4% by weight or less of either or both of Fe and Cr as an essential component, with the balance being Al and impurities is melted and cast, and then homogenized at a temperature of 480°C or higher. After heat treatment, hot rolling is performed, and then cold rolling is performed or no rolling is performed.
~600℃ intermediate annealing, further processing rate 30~80%
Finish cold rolling is performed at
% or less. (2) Contains Mg: 1 to 6% by weight, Mn: 0.1 to 2% by weight as essential components, and also contains 0.4% by weight or less of either or both of Fe and Cr as a total,
Furthermore, Si: 0.2 to 1% by weight, Cu: 0.2 to 2.5
An Al alloy containing one or two selected from % by weight as alloying elements and the remainder being Al and impurities is melted and cast, soaked at a temperature of 480° C. or higher, and then hot rolled, Then, it is subjected to intermediate annealing at 300 to 600°C with or without cold rolling, and further processed at a processing rate of 3.
Deep drawability and re-rollability characterized by performing finish cold rolling at 0 to 80%, and making the area occupation rate of intermetallic compounds with a size range of 0.5 μm or more as seen from the rolled plate surface to 3.5% or less. A method for manufacturing an Al alloy plate for packaging with excellent drawability. (3) Mg: 1 to 6% by weight, Mn: 0.1 to 2% by weight,
Ti: 0.02-0.2% by weight, B: 0.0001-0
．． Contains 03% by weight as an essential component, and also contains Fe and C.
Melting and casting an Al alloy containing either or both of r in a total of 0.4% by weight or less, the remainder being Al and impurities, soaking at a temperature of 480 ° C. or higher, and then hot rolling, Then, it is subjected to intermediate annealing at 300 to 600°C with or without cold rolling, and is further subjected to finish cold rolling at a processing rate of 30 to 80% to form an intermetallic material with a dimension range of 0.5 μm or more as seen from the surface of the rolled plate. A method for producing an Al alloy plate for packaging with excellent deep drawability and redrawability, characterized by controlling the area occupation rate of the compound to 3.5% or less. (4) Mg: 1 to 6% by weight, Mn: 0.1 to 2% by weight,
Ti: 0.02-0.2% by weight, B: 0.0001-0
．． Contains 03% by weight as an essential component, and also contains Fe and C.
Contains either one or both of r as a total of 0.4% by weight or less, and further includes Si: 0.2 to 1% by weight Cu: 0
．． One or two selected from 2 to 2.5% by weight
A containing seeds as alloying elements and the remainder being Al and impurities
The l alloy is melted and cast, soaked at a temperature of 480°C or higher, then hot rolled, then subjected to intermediate annealing at 300 to 600°C with or without cold rolling, and further processed at a working rate of 30 to 600°C. Finish cold rolling is performed at 80%, and the area occupation rate of intermetallic compounds having a dimension range of 0.5 μm or more as seen from the temporary rolling surface is 3.5% or less,
A method for manufacturing an Al alloy plate for packaging with excellent deep drawability and redrawability.