EP0057959B1 - Wrought aluminium alloy - Google Patents

Description

The invention relates to a wrought aluminum alloy, to its use for semi-finished and finished parts and to methods for achieving improved properties, in particular improved strength values for semi-finished and finished parts made of this alloy.

Aluminum can be modified in a variety of ways by alloying other metals with its physical and chemical properties and can be improved to certain goals by means of process measures.

For example, from DE-AS 17 58 801 a method for producing a can body has become known, in which an aluminum alloy is rolled out into a thin strip and then formed by deep drawing and ironing the can body. It is proposed not to start from a soft annealed strip section, as usual, but to use at least 75% strain-hardened aluminum alloy strip with at least 96.5% aluminum, 0.75 to 2.5% iron and 0.1 to for deep drawing and ironing Use 2.5% magnesium and / or 1.1 to 1.5% manganese with silicon and other random additions of at most 1%. In this way, can bodies of sufficient strength can be produced, but not can lids for which a tensile strength in the work-hardened state of at least 350 N / mm ² and an elongation of at least 6% are required. Two different aluminum alloys are therefore required as the starting material for the manufacture of can bodies and lids, with considerable disadvantages having to be accepted, which will be discussed further below.

According to the process known from DE-OS 18 17 243, fine-grained strips can be made from manganese-containing aluminum alloys by holding the strip in the temperature range from 160 ° C to just below the temperature of the complete recrystallization for at least 5 hours before soft annealing is reached . The tensile strength values of a 0.1 mm thick strip of an Al-Mn alloy with 1.2% Mn, 0.6% Fe, 0.3% Si, 0.1% Cu, treated in this way, are in the recrystallized state from 110 to 130 N / mm ² , which is too low for many applications.

According to a further process, which has become known from DE-AS 22 21 660, the elongation at break of high strength aluminum alloys can be improved by a multi-stage annealing and forming process. This method is intended for alloys with 0.05 to 1% iron, 0.05 to 1% silicon and at least one of the alloy additives from the group up to 5% magnesium, less than 3% manganese, less than 1% copper, less than 0 , 5% chromium, less than 0.5% zinc, less than 0.5% zirconium, less than 0.5% titanium and / or less than 0.1% boron, balance aluminum with the usual manufacturing-related impurities of less than 1.5% individually but less than 0.5% may be suitable. Apart from the fact that the process is comparatively complex, the tensile strength values are in the range of 450 N / mm ² and higher or the elongation values are at least 5%, only for an alloy with 0.08% silicon, 0.44% copper, 0 , 77% manganese, 0.10% chromium, 2.9% magnesium, 0.02% zinc, 0.17% iron, 0.01% titanium, balance aluminum, which is due to the high magnesium content for items caused by Deep drawing and ironing or shaped or which must be solderable and enamelable are not suitable.

From all this it follows that the efforts to improve the properties of aluminum alloys are often successful, but at the same time lead to a further application specialization of the materials, which is undesirable in view of the need for raw material and energy savings. The invention has for its object to provide a wrought aluminum alloy that can be used in a variety of ways - with different processing, if applicable Alloying elements. This task is explained in more detail using two special problem areas.

Aluminum cans have been used increasingly for years as disposable containers for beverages, in particular for beer and carbonated soft drinks. They consist of a one-piece can body produced by deep drawing and ironing and a lid with a pull tab flanged after filling. The starting material for the manufacture of the can body and lid are rolled strips made of different aluminum alloys.

An AIMg 4.5 Mn alloy (US designation 5182) in a highly work hardened state (H 19) is usually used for the lids, which after partial softening when baked enamelling has a tensile strength of at least 350 N / mm ² and an elongation of at least 6%. These values must be adhered to so that the lid, which is weakened by embossing along the tear line, can withstand the bursting pressure required for cans filled with CO ₂ -containing beverages and, on the other hand, crack-free flanging is possible. As many years of tests have shown, the alloy mentioned is not suitable for the production of the can bodies, even with less work hardening. Since the desired ratio of height to diameter cannot be achieved by deep drawing alone, the cans are produced by deep drawing and ironing. It has been found that alloys with a Mg content of more than 1% during ironing for abrasion and adhesion on the tool, which leads to undesirable drawing marks and frequent downtimes. An economical production of the can body is not possible with such alloys. An AIMn 1 Mg 1 alloy (US designation 3004) is therefore predominantly used for the production of the can body. After stoving, it has the required tensile strength of at least 270 N / mm ² and an elongation of 1% and can be easily ironed off.

The usual use of two different aluminum alloys for the manufacture of beverage cans in view of the different requirements not only requires a continuous double-track manufacturing process with careful separation of the waste material that is generated in particular when punching out the blanks, it also makes the efforts considerably more difficult Material and energy savings by recycling the empty cans. Depending on the amount of scrap, melting back of recycled cans results in an alloy with approx. 1% Mn and more than 1 but less than 4.5% Mg, which is not suitable for the manufacture of lids or the manufacture of can bodies without alloying measures. In order to get one of the two usable alloys, expensive raw metals have to be alloyed, whereby the recycling loses economic interest for the individual manufacturer and therefore the economically necessary return of used materials is not promoted to the desired extent.

In order to overcome the difficulties mentioned, a process for the production of tapes for cover manufacture has been proposed in US Pat. No. 3,787,248, which starts from an alloy which has essentially the same composition as that used for the can body.

The alloy should contain 0.5 to 2% Mn and 0.4 to 2% Mg, the balance essentially Al. After homogenization annealing for 2 to 24 hours at about 455 to 655 ° C (850 to 1 150 ° F), the material is rolled hot and cold in several steps while observing certain starting temperatures and rolling degrees, and then subjected to heat treatment to stabilize the structural condition. In the most favorable case, a tensile strength of 316 N / mm ² (45 psi) is achieved with an elongation of 4%. It can be seen that despite a comparatively complex manufacturing process, the requirements mentioned at the outset are not met. These could be achieved if the upper part of the specified Mg range, ie over 1 to 2%, were used. Then the alloy is certainly not suitable for the production of can bodies by ironing. The method proposed in the US patent can therefore not be regarded as a satisfactory compromise.

According to another proposal (DE-OS 2901 020), an alloy with 0.4 to 1% Mn and 1.3 to 2.5% Mg is assumed, which is to be cast continuously into a strip using a strip casting machine. The cast strip should be rolled and coiled warm, preferably between 490 and 280 ° C, at least 70%, then cooled in still air and finally cold rolled to its final thickness. The tensile strength values achieved in the work hardened state are below 350 N / mm ² and fall to 330 to 310 N / mm ² depending on the annealing temperature used to simulate the lacquer baking. The desired elongation of at least 6% is only achieved if the annealing temperature is at least 200 ° C, but the tensile strength is only about 325 N / mm ² . It also applies to this proposal that the desired values for the cover material could not be achieved. With regard to the difficulties in ironing, it is only mentioned that the alloy used has a lower tendency to stick to the tool than conventional can band alloys. Overall, therefore, the subject of DE-OS 29 01 020 does not bring a satisfactory solution to the problem described.

There is therefore still the task of specifying an aluminum alloy which is equally suitable for the lid and the can body.

For other areas of application, solderable and enamelable aluminum alloys are required, which must also have certain minimum strength values in the fully recrystallized state.

Semi-finished products and finished parts are designated as solderable and enamelable, which - apart from a possibly necessary degreasing - do not require extensive pretreatment by chromating, anodizing, plating, galvanizing or the like. Completely recrystallized is the thermodynamically stable state of the structure, which is also referred to as “soft” in the case of semi-finished or finished parts.

An Al-Mn alloy (material no. 3.0515) is known from DIN 1725 in conjunction with DIN 1745, part 1 (edition December 1976), which has a minimum tensile strength of 90 N / mm2 and a 0.2- Has a yield strength of 35 N / mm ² . By adding Cu (material no. 3.0517) the tensile strength can be improved to 145 N / mm ² , but the 0.2 yield strength remains at 35 N / mm ² . By adding Mg (material no. 3.026) the minimum tensile strength can be increased to 155 N / mm ² and the 0.2 yield strength to 60 N / mm ² in the soft state.

Both strength-increasing measures do not meet the requirements set here and are disadvantageous in other respects. While the addition of Cu in amounts of 0.05 to 0.20% already has a considerable impact on the corrosion resistance, an Al-Mn alloy with 0.8 to 1.3% Mg can no longer be soldered or enamelled. The conditions mentioned at the beginning cannot therefore be met in this way.

Also known are solderable and enamelable AI-Mn alloys with improved strength properties shaft, the scope of which has been expanded by the addition of zirconium and / or chromium (cf. DE-PS 16 08 198, 16 08 766, DE-AS 25 29 064, DE-OS 25 55 095). In these cases, however, it is only a question of producing a structure which is inert to recrystallization, ie a shift in the drop in strength towards higher temperatures. In the "soft" condition, the strength values of this alloy are again significantly below the desired values.

Parts made from such alloys can be exposed to higher temperatures than conventional Al-Mn alloys during manufacture (soldering and enamelling processes) or when used as intended, because the Zr and / or Cr addition significantly reduces the cold-forming results Structural hardening prevented when exposed to temperature. However, the recrystallization inhibition only remains up to a certain temperature or exposure time. If certain limit values are exceeded during the manufacture of the parts or during their intended use, the structure of these alloys often changes into the thermodynamically stable, i.e. H. soft state, which means that the strength values are no longer sufficient for many applications.

The task on which the invention is based can therefore be supplemented to the extent that an aluminum alloy is sought which satisfies both all the requirements which must be met in the manufacture of beverage cans and the requirements which are required in the manufacture of solderable and enamelable semi-finished and finished parts .

To solve this problem, a wrought aluminum alloy is proposed, which is characterized by 1.15 to 2% manganese, more than 1.0 and up to 2.0% silicon, 0.25 to 0.65% magnesium, 0.2 to 1.0% iron, at most 0.3% copper, at most 0.2% zinc, at most 0.1% zirconium, at most 0.1% titanium, balance aluminum, including a total of at most 0.2% other impurities.

The silicon content of the wrought aluminum alloy is preferably 1.2 to 1.8% or even better 1.38 to 1.57%. According to a further embodiment of the inventive concept, the wrought aluminum alloy can also have a silicon content of 0.85 to 2% if the alloy contents are also coordinated with one another as follows:

Furthermore, it is possible in the wrought aluminum alloy according to the invention to combine the aforementioned restricted silicon areas with the above tuning conditions.

To further improve strength and elongation, the alloy contains 0.1 to 0.3% Cu, preferably 0.15 to 0.25%.

Another aspect of the inventive concept relates to semi-finished products, in particular rolled strips, which consist of an alloy according to the above-mentioned compositions. In particular, the idea of the invention also relates to semi-finished products or finished parts made of this alloy, which in the work-hardened state have a tensile strength of at least 350 N / mm ² and an elongation of at least 6%. On the other hand, the semi-finished or finished parts made of this alloy in the fully recrystallized state should have a tensile strength of at least 150 N / mm ² and a yield strength of at least 80 N / mm ² . Finally, semi-finished or finished parts can be produced from the alloy, which have a tensile strength of at least 350 N / mm ² and an elongation of at least 6% in the work hardened state and which have a tensile strength of at least 150 N / mm2 and a yield strength of in the fully recrystallized state have at least 80 N / mm2.

To produce rolled strips from an alloy according to the composition according to the invention, the procedure is expediently such that a casting block is rolled hot and / or cold to an intermediate thickness D _z , that the intermediate strip is then subjected to a recrystallization annealing at 450 to 580 ° C. and that the intermediate strip is finally cooled at a minimum speed V (° K / s) and rolled to the final thickness D _a with a minimum rolling degree ϕ (%). Depending on the required ultimate strength R, (N / mm ² ), the following conditions must be met during manufacture:

With a required final strength of the rolled strip in the range of 220 to 275 N / mm ² , the aforementioned method can be modified in such a way that the intermediate strip is annealed at 450 to 580 ° C, cooled in still air and with a final rolling degree ϕ = f (R _m ) is cold rolled to final thickness according to the diagram in FIG. On the other hand, in the case of a required final strength in the range from 220 to 275 N / mm ^{2, the procedure can} also be such that, in the usual way, the strip is rolled directly to its final thickness, then the strip is annealed at 450 to 580 ° C and recrystallized and at a speed V = f (R _m ) cooled to below 250 ° C according to the diagram in Figure 3. If there is a cast strip produced in the strip casting process that has been cooled at least 10 ° K / s, hot and / or cold can be rolled down to the final thickness without recrystallization annealing. In general, it is expedient to roll to an intermediate thickness D _z of 1 to 4 mm or to a final thickness D _a of 0.20 to 0.50 mm. The alloy or the rolled strips produced therefrom are preferably used for finished parts, in particular cans, but also only for can bodies or can lids.

For the production of solderable and enamelable semi-finished products or finished parts from the alloy according to the invention, the procedure is such that the semi-finished products or finished parts are finally subjected to a recrystallizing heat treatment of at least 3 minutes at 450 to 600 ° C. This final heat treatment can expediently take place simultaneously with the enamel baking process or with the soldering process.

According to the invention, it is possible to start from a single aluminum alloy for the manufacture of the can body and can lid. This eliminates all the difficulties that arise from the usual use of two different alloys. The return of the can material has become much more interesting economically and for everyone involved, i. H. the can manufacturers, the bottlers and the end users, there is a higher incentive to recycle the material of the empty beverage cans.

A very important advantage of the invention is that the magnesium content can be significantly reduced compared to the aluminum alloys previously used for beverage cans. In 1978 approximately 1 million tons of rolled strips were used for beverage cans in the USA. With a high recycling rate of 40%, there remains a need for new metal of 600,000 t. Assuming that 1% magnesium can be replaced by 1% silicon for this amount, there is a saving with a price difference for these metals of about 3 DM / kg and a requirement for alloy metal of 6,000 t of 6,000 tx 3,000 DM / t = ₁₈ million DM when using the invention to provide the annual requirement for strip material.

For the preparation of the assumed 40% recycled can scrap to 400000t t can band (of which 320,000 t for can bodies and 80,000 t for can lids), about 2,000 t magnesium are used to put on the lid material and approx. 78,000 t metallurgical aluminum to dilute the can body material needed. If the can scrap were made of a uniform material according to the invention, the material would be reusable practically without the use of new metal, which would result in a further saving of the order of DM 6 million solely from the elimination of the costs for the magnesium pneumatics. The savings mentioned above are of course primarily dependent on metal prices. However, it is foreseeable that even higher savings can be achieved in the future because the production of pure metals is associated with high energy consumption and the energy costs are expected to continue to rise.

For further explanation, reference is made to the figures.

FIG. 1 shows the tensile strength values achieved as a function of the magnesium content of the alloy for different cooling rates and degrees of rolling after recrystallization annealing at 520 ° C. In samples 1 and 2 according to table 1, the magnesium content is below 0.25% and only comparatively low tensile strength values are achieved under all cooling and rolling conditions (see table 2). In contrast, samples 3 to 7, practically independent of the magnesium content, which was varied between 0.26 and 0.66%, achieve significantly higher tensile strength values. Sample 7 lies in the Mg content outside the claimed Mg range and is therefore not included in Table 2. A tensile strength of more than 370 N / mm ² results from cooling at 90 ° K / s and a rolling degree of 75% (upper curve). With the same cooling rate, but only 45% rolling, the tensile strength values are around 325 N / mm ² (lower curve). In the middle curve, the samples were cooled with only 2 ° K / s, but were rolled down to the final thickness with 82% rolling; tensile strength values of around 335 N / mm ^{2 result.} These test results show that the magnesium content above 0.25% has no influence on the final strength and that it can therefore be adjusted in the area examined to any other conditions in the manufacture of beverage cans. Furthermore, it can be seen that if the process parameters are selected appropriately, the tensile strength of 350 N / mm ² required for the can lid can be achieved and clearly exceeded, so that the material fulfills the requirements even after partial softening when baking the paint. On the other hand, the two lower curves show that the same can be achieved with a high cooling rate and low rolling rate as with a low cooling rate and high rolling rate. If no continuous, annealing and quenching system is available for the production of the strips, the same can be achieved by a higher degree of rolling. Conversely, the final rolling can be carried out with a smaller rolling degree and thus more economically if correspondingly high cooling speeds can be achieved.

läßt sich die Ungleichung auch wie folgt schreiben :

This relationship is formulated in the above inequality, taking into account the required ultimate strength, and is shown graphically again in FIG. 4 for various tensile strength values. As applies to the degree of rolling

the inequality can also be written as follows:

For practical operation, you can easily calculate the required intermediate thickness for a given final strength and depending on the achievable cooling rate if the final thickness is specified.

It should also be pointed out that the inequality for ϕ only applies to values R _m ≥ 275 N / mm ² . At R _m = 275 N / mm ² , the value for ϕ is - 0, ie no further rolling would be necessary regardless of the cooling rate.

When applying the inventive concept, the strength range above 275 N / mm ² will mainly matter, but also for the range below it, process conditions can be specified for the alloy which lead to a predetermined final strength.

Figure 2 shows the required degree of rolling depending on the required strength for a strip annealed at 520 ° C, which was cooled in still air at about 2 ° K / s. Such a strip has a strength of approximately 220 N / mm ² , which can be increased to approximately 290 N / mm ² with a degree of rolling of 60%.

Figure shows the required cooling rate depending on a predetermined final strength for a strip rolled to final thickness and then annealed at 520 ° C.

On the basis of the alloy according to the invention, a method is accordingly specified with which strips for the manufacture of beverage cans can be produced, which can have any final strength required in this area of application. The strip material thus provided can be used for the manufacture of can lids for which a strength of at least 350 N / mm ^{2 is} required; but it can also be used for the manufacture of the can body by deep drawing and ironing, because it does not pose any difficulties in these forming operations because of the low magnesium content. This means that a way has been found for the manufacture of beverage cans that simplifies production considerably, makes recycling of the old material more economically interesting and brings considerable savings.

In the production of solderable and enamelable semi-finished or finished parts, the final heat treatment is advantageously carried out at 450 to 600 ° C. It is particularly advantageous if the final heat treatment for enamelled semi-finished or finished parts is carried out simultaneously with the enamel baking process. In the case of soldered semi-finished products or finished parts, the final heat treatment is advantageously carried out simultaneously with the soldering process. To further increase the tensile strength and 0.2-stretch limit values, the semi-finished or finished parts can be subjected to forced cooling after the final heat treatment. If the final heat treatment is to be carried out at a temperature close to the upper limit, the magnesium content of the alloy must be limited to 0.25 to 0.50%.

In a similar process (cf. DE-PS 27 54 673), the desired tensile strength values of at least 150 N / mm ² , but not the required 0.2, are achieved with a comparable alloy, which however can contain a maximum of 0.2% Mg -Stretch limit values of at least 80 N / mm ² reached. The latter are 50 N / mm ² or less above, regardless of the temperature of the final heat treatment used. They are not sufficient for a number of use cases. Surprisingly, it has been found that the 0.2 yield strength can still be improved considerably if the Mg content is increased to 0.25 to 0.65% without disadvantages in terms of solderability and enamelling. With Mg contents of more than 0.2%, the enameability of Al-Mn alloys was only possible after extensive pretreatment. In the literature, it is even required to keep the Mg content below 0.01 or 0.05% (cf. aluminum paperback, 14th edition (1974) page 734, section 4; Z. aluminum, 47th year (1971) page 688, plate 1).

Samples with the composition according to Table 1 were examined. Samples 1 and 2 correspond to DE-PS 27 54 673, while the others have an increasing Mg content within the range claimed. The strength values achieved after 30 minutes of annealing at a conventional enamel baking temperature of 560 ° C are shown in Table 2. Tensile strength values of over 200 N / mm ² and 0.2 yield strength values of 85 to 98 N / mm ^{2 were achieved} with constant elongation values of around 20%. All samples passed the enamel adhesion test according to DEZ F 17 of the German enamel center after 96 hours in an antimony trichloride solution. These results contradict the popular belief that the addition of magnesium to Al-Mn alloys to be enamelled should be avoided. (Z. Aluminum, 47th year (1971), page 688, right column, paragraph 3).

In FIG. 5, for an alloy with 1.55 Mn, 1.53% Si, 0.39% Mg, 0.61% Fe, 0.09% Zr, balance aluminum and impurities, the increase in tensile strength and 0.2 is -Stretch limit values are shown depending on the temperature of the final heat treatment. It can be clearly seen that above 450 ° C there is a remarkable increase in both values. Without the addition of magnesium in the claimed amount, there is no increase in the 0.2 yield strength and tensile strength values do not significantly exceed 160 N / mm ² . (cf. DE-AS 27 54 673, diagram I) In contrast, according to the invention, for the “soft” state, the 0.2 yield strength can be raised to over 80 N / mm ² and the tensile strength increased to over 200 N / mm ² .

When brazing with flux, magnesium is considered to be harmful to wetting in Al-Mn alloys. It can be assumed that this disadvantage arises just as little as an impairment of the enamel adhesion if the alloy components are matched to one another in accordance with the invention. However, since higher temperatures are usually used for brazing than for enamelling, it should also be noted that the solidus temperature is reduced with increasing Mg content. This relationship can be seen in FIG. 6. For such applications, the upper limit of the Mg content must therefore be reduced depending on the temperature of the soldering process. In general, it is sufficient to limit the Mg content to 0.5% in order to avoid melting at a brazing temperature of up to 600 ° C.

Claims (21)

1. A wrought aluminum alloy, characterized in that it consists of 1.15 to 2.0 % manganese, more than 1.0 and up to 2.0 % silicon, 0.25 to 0.65 % magnesium, 0.2 to 1.0 % iron, not in excess of 0.3 % copper, not in excess of 0.2 % zinc, not in excess of 0.1 % zirconium, not in excess of 0.1 % titanium, balance aluminum including impurities not in excess of a total of 0.2 %.

2. A wrought aluminum alloy according to claim 1 characterized by a silicon content of 1.2 to 1.8 %.

3. A wrought aluminum alloy according to claim 1, characterized by an silicon content of 1.38 to 1.57%.

4. A wrought aluminum alloy according to any of claims 1 to 3, which contains 0.85 to 2.0 % silicon and wherein the contents of alloying elements meet the following conditions :

0.3(2 Mg+Fe+Mn+1)≤Si

M n ≥1.5 Fe

Mn + Fe 1.5

Mn + Si 2.3

5. A wrought aluminum alloy according to claim 4, wherein the silicon content is within the ranges stated in claims 1 to 3.

6. A wrought aluminum alloy according to any of claims 1 to 5, wherein the copper content is 0.1 to 0.3 % preferably 0.15 to 0.25 %.

7. Semifinished products made of an alloy according to any of claims 1 to 6.

8. Rolled strip made of an alloy according to any of claims 1 to 6.

9. Semifinished or finished products made of an alloy according to any of claims 1 to 6, characterized in that they have in a cold-worked state an ultimate tensile strength of at least 350 N/mm² and an elongation of at least 6 %.

10. Semifinished or finished products made of an alloy according to any of claims 1 to 6, characterized in that they have in a fully recrystallized state an ultimate tensile strength of at least 150 N/mm² and a 0.2 % offset yield point of at least 80 N/mm².

11. Semifinished or finished products made of an alloy according to any of claims 1 to 6, characterized in that they have in the cold-worked state an ultimate tensile strength of at least 350 N/mm² and an elongation of at least 6 % and have in a fully recrystallized state an ultimate tensile strength of a least 150 N/mm² and a 0.2 % offset yield point of at least 80 N/mm².

12. A process of manufacturing rolled strip from an alloy according to any of claims 1 to 6, characterized in that an ingot is hot-rolled and/or cold-rolled to an intermediate thickness D_z and that the resulting intermediate strip is process-annealed at 450 to 580 °C and is subsequently cooled at a controlled rate of at least V(°K/s) and is than rolled to a final thickness D₈ with a controlled reduction of a least <p (%).

13. A process according to claim 12, characterized in that in dependence on the required final strength R_m (N/mm²) the following condition is maintained :

14. A process according to claim 12 or 13, characterized in that when a final strength in the range of 220 to 275 N/mm² is required the intermediate strip is annealed at 450 to 580 °C, then cooled in still air and subsequently cold-rolled to the final thickness with a reduction ϕ = f(R_m) in accordance with the graph of Figure 2.

15. A process according to claim 12 or 13, characterized in that when a final strength in the range of 220 to 275 N/mm² is required the ingot is rolled in the conventional manner directly to the final thickness and is then process-annealed at 450 to 580 °C and subsequently cooled below 250 °C at a rate V = f(R_m) according to the graph of Figure 3.

16. A process according to claim 11 or 12, characterized in that the starting material consists of a cast strip which has been cooled at least at 10 °K/sec and which is hot-rolled and/or cold-rolled directly to the final thickness without process-annealing.

17. A process according to any of claims 12 to 14, characterized in that the casting is rolled to an intermediate thickness D_z of 1 to 4 mm.

18. A process according to any of claims 12 to 17, characterized in that the strip is rolled to a final thickness D of 0.20 to 0.50 mm.

19. The use of the alloy according to any of claims 1 to 6 or of a rolled strip manufactured according to any of claims 11 to 17 for the manufacture of finished products, particularly cans or can bodies and can covers.

20. A process of manufacturing semifinished or finished products which can be soldered and enameled from an alloy according to any of claims 1 to 6, characterized in that the semifinished or finished products are subjected to a recrystallizing final heat treatment at 450 to 600 °C for at least 3 minutes.

21. A process according to claim 19 characterized in that the final heat treatment is carried out during the stoving of the enamel or the soldering operation.

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