EA009227B1 - THIN STRIPS OR FOILS OF AlFeSI ALLOY - Google Patents

Abstract

The invention relates to a thin strip or foil, having a thickness of 6 to 200 mkm, preferably, of 6 to 50 mkm, and composed of an alloy containing (in weight %) Si: 1.0 to 1.5, Fe: 1.0 to 1.5, Cu < 0.2, Mn < 0.1, other elements < 0.05 each up to a total < 0.15, the remainder being Al. The annealed thin strip or foil has a tensile strength R> 110 MPa for a thickness > 9 mkm and > 100 MPa for a thickness of 6 to 9 mkm, and an elastic limit R> 70 MPa. Preferably, said alloy has a silicon content of 1.1 to 1.3 % and an iron content of 1.0 to 1.2 %. The aforementioned thin strips or foils may be used especially for the production of multilayer composites, overcaps for bottles or aluminium wrappings.

Description

FIELD OF THE INVENTION

The invention relates to a foil or strips with a thickness of less than 200 microns, mainly 50 microns thick, from an aluminum-silicon-silicon alloy mainly without manganese and to a method for manufacturing such foil or strips. These strips can be obtained by conventional semi-continuous casting of plates or their continuous casting, for example, on a tape installation or on a roll mold.

State of the art

The trend in the market of aluminum alloy foil is a constant decrease in their thickness when used for a specific purpose while maintaining high mechanical properties and good deformability. Often alloys with a very low manganese content are used for the foil, as is the case, for example, in alloy 8111 with the composition, wt.%, Registered in the Aluminum Association: δί - 0.30-1.1; Her - 0.40-1.0; Cu <0.10; Mn <0.10.

The absence of manganese simplifies recrystallization during final annealing, however, at a thickness of less than 100 μm, the tensile strength В _t remains insufficient. Therefore, to satisfy market demand, it is necessary to create new alloys and / or optimize processing processes.

To increase the mechanical strength, manganese is usually added, as is the case, for example, in alloy 8006, which, as registered by the Aluminum Association, includes, wt.%: 8ΐ <0.40; Her - 1.2-2.0; Cu <0.30; MP - 0.30-1.0; Md <0.10.

The addition of manganese enhances the hardness of the material. As described in the patent I8 6517646 in the name of the applicant, the mechanical properties obtained in the alloy with the composition: δί - 0.23%, Its 1.26%, Cu - 0.017%, Mn - 0.37%, Md - 0.0032% , Τί - 0.008%, in combination with the optimal processing process allow to obtain a value of B _t = 103 MPa with a thickness of 6.6 μm.

It is also possible to improve mechanical properties by adding a small amount of manganese to the 8000 series alloys containing iron. The patent application UO 02/64848 (A1sap 1p1egpa1yupa1) describes the preparation of thin strips by continuous casting of an A1Ee81 alloy with a content of 1.2-1.7% Ee and 0.35-0.8% δί. By adding manganese in an amount of 0.07-0.20% to the alloy, high mechanical strength is achieved. Such an addition of manganese is considered necessary to obtain small grains after final annealing.

Therefore, manganese is an element that improves the mechanical properties of 8000 alloys. However, manganese in the form of a solid solution or a fine precipitate is able to block or slow down recrystallization during final annealing. Therefore, it is necessary to carefully control the allocation of phases containing manganese at each stage of the process, which is often difficult. Any deviation from the processing process leads to important consequences affecting the efficiency of the final annealing. Therefore, it is very important to develop an alloy without a manganese content, but, nevertheless, with high mechanical properties.

The patent υδ 5503689 (Веупо1бк Ме1а1к) describes a method for producing a thin strip from an alloy with a content of 0.30-1.0% δί, 0.40-1.0% Ee, less than 0.25% Cu and less than 0.1% Mp continuous casting and cold rolling without intermediate annealing. The preferred content of iron and silicon is 0.6-0.75%.

The patent υδ 5725695 (Веупо1бк Ме1а1к) describes a technological process for the same composition with intermediate annealing at 400-440 ° С (750-825 ° Е) and final recrystallization annealing at 288 ° С (550 ° Е). The ratio between the content of δί and Its is equal to or more than 1. In the examples, the obtained maximum tensile strength is 90 MPa (13.13 kk1) (kk1 - thousand feet per square inch), the maximum elastic limit is 39.1 MPa (5.68 kk1) and elongation of 11.37% with a thickness of 46 μm (0.00185 '). However, for some applications, such mechanical properties are insufficient.

For alloys obtained by continuous casting, it is often required to carry out high-temperature heat treatment in order to reduce the harmful effect of segregation by resorption of clusters of released particles and homogenization of the structure by thickness. The effect of homogenization at a temperature of 600 ° C on alloy 8011 (with composition: 0.71% Her, 0.77% δί, 0.038% Cu, 0.006% Mp, 98.45% A1), obtained by casting in a roll mold, is described in the article Υ. B1go1 Sep1eg1she δed ^ foodΐ ^ op w a T \ ut-Bo11 Sac! AA8011 A11ou, A1it1shit, No. 74, 1998, p. 318-321. In this case, a modification of the precipitated phases occurs and the inhomogeneity decreases. A decrease in axial segregation subsequently allows the porosity of a very thin foil to be limited and the deformability to be improved.

For economic reasons, it is advisable to limit the temperature of the heat treatment. In alloy 8111 with the composition: 0.7% Ea, 0.7% δί, Mn <0.02, 2n <0.02%, Cu <0.02%, the onset of phase transformation and complete recrystallization at a temperature of 460 ° C was noted, even if more complete conversion requires annealing at 550-580 ° С (see M. δ1atοvа and others. Vekropke ok AA8006 apb АА8111 δίΓίρ-Сак! Woweb А11оук 1о Ηί§1ι Tetrega! he AppeaLpd, 1CAA-6, 1998 ) Therefore, low temperature homogenization can be used for manganese-free alloys.

However, during processing after homogenization to obtain small thicknesses, it is customary to use intermediate annealing to soften the metal. For alloys containing manganese, controlled pro

- 1 009227 intermittent annealing, as a rule, requires high-temperature heat treatment (at temperatures above 400 ° C) in order to ensure recrystallization.

For alloys of type 8000 without a manganese content, heat treatment at a lower temperature can be used than for alloys of type 8006.

The patent application 99/23269 (Νΐρροπ I.ίρΙιΙ Me1a1 apb A1sap 1p1egpaiopa1) describes a method that is applicable to A1Pe81 alloys with a content of 0.2-1.0% 8ΐ and 0.3-1.2% Pe at a ratio δΐ / Re from 0.4 to 1.2. For this alloy, intermediate annealing is carried out in two stages, at the first stage at a temperature of 350-450 ° C and at the second at a temperature of 200-330 ° C. The purpose of this method is to reduce the surface defects of the foil. Mechanical properties not indicated.

The aim of the invention is to obtain a thin foil or strips of A1Re81 alloy without the addition of manganese, with high mechanical strength while maintaining good deformability, using the most economical industrial technology.

SUMMARY OF THE INVENTION

The object of the invention is a thin sheet with a thickness of from 6 to 200 microns, preferably from 6 to 50 microns, from an alloy with a content, wt.%: 8ΐ - 1.0-1.5; Re - 1.0-1.5; Cu <0.2; Mn <0.1, the rest of the elements <0.15, each of which <0.05, the rest A1, preferably provided that δΐ / Pe> 0.95, while the tensile strength in the annealed state is K _t > 110 MPa with a thickness of> 9 μm and> 100 MPa with a thickness of 6-9 μm. The elastic limit Kd _{2 of a} thin foil (measured on cut samples) is predominantly more than 70 MPa. Depending on the thickness of the foil, the elongation at break exceeds the following values:

Thickness, microns A,%, more than: preferably more than: 6-9 3 4 9-15 5 7 15-25 10 fifteen 25-50 eighteen 25 50 - 200 twenty 25

Preferably, the alloy contains silicon in an amount of 1.1-1.3% and iron in an amount of 1.01.2%.

The object of the invention is also a method for producing thin strips with a thickness of less than 200 microns from an A1Ре81 alloy with a composition, wt.%: 8ΐ - 1.0-1.5; Re - 1.0-1.5; Cu <0.2; Mn <0.1; the remaining elements in the amount of <0.15, of which each element is <0.05, the rest is A1, preferably provided that δΐ / Pe> 0.95, which includes the manufacture of the initial strip or semi-continuous vertical casting of the plate followed by hot rolling or continuous casting, if necessary followed by hot rolling, while the initial strip is cold rolled to a final thickness, if necessary, with intermediate annealing for 2-20 hours at a temperature of 250-350 ° C, preferably 280-340 ° C, and final annealing at tamper round 200-370 ° C.

The foil or strip according to the invention is made from A1Pe81 8000 alloys, which practically do not contain manganese or contain it in an amount, usually less than 0.1%. The content of iron and silicon significantly exceeds their content in alloys 8011 and 8111, which are A1Pe81 alloys, the most commonly used in the manufacture of foil without manganese. The preferred composition corresponds to an alloy containing 1.1-1.3% silicon and 1.0-1.2% iron.

Preferably, the composition of the alloys according to the invention is such that the ratio between the silicon content and the iron content is δΐ / Pe> 0.95. In the annealed state (state 0), it has mechanical strength, which is unusual for alloys of this composition, while the tensile strength K _t reaches more than 110 MPa, even more than 115 MPa, with a thickness of more than 9 μm and more than 100 MPa with a thickness of 6-9 μm, the conditional elastic limit with a tolerance of 0.2% AND ₍ ,, ₂ > 70 MPa. Such high mechanical strength is not achieved due to deformability, since in comparison with alloys 8011 and 8111, the elongation indices are kept at least the same, at the same time, the pressure at break is higher.

Such high mechanical properties are obtained both for strips made of plates obtained by traditional vertical semi-continuous casting and hot rolling, and for strips obtained by continuous casting either on a tape machine or on a roll. Continuous casting on a tape machine is followed by subsequent hot rolling.

Hot rolled strips or untreated strips in the case of continuous casting in a roll mold can, if necessary, undergo low-temperature homogenization (at 450-500 ° C) to reduce axial segregation, which can cause a decrease in deformability at a final thickness. Such a low-temperature heat treatment is sufficient to absorb possible axial segregations in alloys without a manganese content. Then the strips are cold rolled either to a final thickness or to an intermediate thickness of 0.5 to 5 mm, at which they are intermediate annealed. In contrast to alloys containing manganese, it is possible to conduct intermediate annealing at a relatively low temperature from 250 to

- 2 009227

350 ° C, preferably from 280 to 340 ° C, for more than 2 hours. This temperature range, although already described in the literature, in particular in the above patent application AO 02/064848, is below the usual range of more than 400 ° C.

The applicant has found that the use of low-temperature heat treatment for A1Te81 alloy, in particular, an alloy with a composition of 81 / Te> 0.95, when refusing intermediate annealing in the case when it is technically possible, leads to a sharp increase in mechanical strength, reaching at least 15% , compared with the state after conventional intermediate annealing. Such high mechanical strength is achieved with increased deformability, measured by the pressure at break or the height of the dome according to the standard 18O 2758.

Final annealing is carried out at a temperature of 200-370 ° C for 1-72 hours. The duration of annealing is due to the quality of degreasing of the foil surface. After final annealing, a fine-grained structure is formed in which the grain size, measured by image analysis under an electron scanning microscope, is on average less than 3 microns.

The use of low-temperature homogenization or its absence and the use of low-temperature intermediate annealing or a complete rejection of it provides, in addition to the economic advantage, the possibility of obtaining small grains. The grain size decreases by approximately 30% compared with heat treatment at a higher temperature, which leads to an increase in the mechanical properties of Co, ₂ and K _t , which at small thicknesses of the product are determined by the number of compacted grains. This advantage is not achieved due to the deterioration of elongation, since the increase in the number of grains in thickness also limits the risk of a local defect with one or two grains in the thickness of the foil.

The foil according to the invention is particularly suitable for applications in which good mechanical strength and high deformability are simultaneously required, such as, for example, in the production of multilayer composite materials, in particular for the manufacture of lids for packaging fresh products, caps for capping or household aluminum.

Information confirming the possibility of carrying out the invention

Example 1

In order to show the effect of the composition of the alloy, two 6.1 mm thick strips of alloy A according to the invention and type B 8111 alloy with the composition (wt.%) Shown in Table 1 were made by continuous casting in a roll mold. one.

Table 1

Alloy 81 Re Si Mp _Yo SG Τΐ IN BUT 1.17 1,11 0.001 0.003 0,0004 0,0007 0.006 0,0005 IN 0.7 0.7 0.001 0.003 0,0005 0.001 0.007 0,0005

The strips were cold rolled to a thickness of 2 mm and subjected to intermediate annealing for 5 h at 320 ° C. Then, in several passes, they were again cold rolled to a final thickness of 38 μm. After this, intermediate annealing was carried out for 40 hours at 270 ° C.

In each case, mechanical properties were measured: tensile strength K _t (MPa), conditional elastic limit at 0.2% K ₀ , ₂ and elongation A (%) according to French standard ΝΤ-ΕΝ 5462, as well as pressure at break in air Re (kPa), measured according to the standard 18О 2758, and the height of the dome Nb (mm). The results are shown in table. 2.

table 2

Alloy K _t , MPa K-0 2, MPa BUT, % Re, kPa on BUT 123 76 thirty 394 9.2 IN 104 54 15.8 284 6.6

It was noted that, in contrast to alloy B of type 8111, the tensile strength of the tape from alloy A significantly exceeded 110 MPa, and the elastic limit exceeded 70 MPa. In addition, the pressure at break and elongation were also higher, as a result of which this alloy simultaneously had strength and deformability.

Example 2

By the continuous casting method in a roll mold, a strip of 6.1 mm thick A as shown in Example 1 was obtained. The strip was cold rolled to a thickness of 2 mm. Part of this strip was subjected to intermediate annealing, which is usual for an alloy of this type, for 5 hours at 500 ° C. Another part of the strip was subjected to intermediate annealing according to the invention for 5 hours at 320 ° C. Both parts of the strip were then cold rolled in several passes to a final thickness of 10.5 μm. After that, they were subjected to final annealing for 40 h at 270 ° C.

We measured the same properties as in example 1, their results are shown in table. 3.

- 3 009227

Table 3

Intermediate annealing K. _t , MPa Co., 2, MPa BUT, % Re, kPa H4 mm 470 ° C 99 63 7.3 71 5.1 320 ° C 117 84 8.1 92 5.7

It was found that a decrease in the temperature of the intermediate annealing simultaneously leads to an increase in mechanical strength, elongation, tensile strength and deformability.

The average grain size, measured by image analysis under an electron scanning microscope, was 3.6 μm after annealing at 470 ° C and 2.3 μm after annealing at 320 ° C. Thus, the improvement of mechanical properties after low-temperature annealing is associated with a decrease in grain size after final annealing.

Claims (12)

CLAIM 1. A thin strip with a thickness of 6 to 200 microns from an alloy of the following composition, wt.%: Δΐ - 1.0-1.5; Re 1.0-1.5; Cu <0.2; Mn <0.1; the remaining elements in the amount of <0.15, each of which is <0.05, the rest is A1, the tensile strength K _{t of} which in the annealed state is more than 110 MPa with a thickness of more than 9 microns and more than 100 MPa with a thickness of 6 to 9 microns. 2. The thin strip according to claim 1, characterized in that it has a thickness of from 6 to 50 microns. 3. The thin strip according to claim 1 or 2, characterized in that its tensile strength K _t in the annealed state is more than 115 MPa with a thickness of 9 μm. 4. A thin strip according to any one of claims 1 to 3, characterized in that its elastic limit Κμ, ₂ in the annealed state exceeds 70 MPa. 5. A thin strip according to any one of claims 1 to 4, characterized in that its elongation A at break is, depending on the thickness: Thickness, microns A,%, more: preferably more than: 6-9 3 4 9-15 5 7 15-25 10 fifteen 25-50 eighteen 25 50 - 200 twenty 25 6. A thin strip according to any one of claims 1 to 5, characterized in that the alloy has a composition in which δΐ / Pe> 0.95. 7. A thin strip according to any one of claims 1 to 6, characterized in that the silicon content in the alloy is 1.1-1.3%, the iron content is 1.0-1.2%. 8. A method of obtaining thin strips with a thickness of less than 200 microns from an A1Re81 alloy of the following composition, wt.%: 8Ϊ - 1.0-1.5; Re - 1.0-1.5; Cu <0.2; Mn <0.1; the remaining elements in the amount of <0.15, of which each element is <0.05, the rest is A1, including the manufacture of the initial strip or semi-continuous vertical casting of the plate and hot rolling, or continuous casting followed by hot rolling, while the initial strip is subjected to cold rolling to a final thickness with intermediate annealing at a temperature of 250-350 ° С and final annealing at a temperature of 200-370 ° С. 9. The method according to claim 8, characterized in that the intermediate annealing is carried out at a temperature of 280-340 ° C. 10. The method according to claim 8 or 9, characterized in that the alloy has a composition in which δΐ / Pe> 0.95. 11. The method according to any one of claims 8 to 10, characterized in that before cold rolling the initial strip is subjected to homogenization at a temperature of 450-500 ° C. 12. The method according to any one of claims 8 to 11, characterized in that the strip is obtained by continuous casting in a roll mold.