DE1483228C - Aluminum alloy with high creep strength - Google Patents

Description

1 2

The invention relates to aluminum alloys with water or molten salt at a temperature

high creep strength, the copper, manganese and temperature from 150 to 250 ° C are used.

Contain titanium, as well as their preferred use It was found that in certain construction

and a preferred method of heat treating parts that require extensive machining in full

development of these alloys. 5 heat-treated condition had to be carried out

Wrought aluminum alloys, the copper, man and in which the dimensional tolerances within

gan and titanium are used for aircraft engines - very narrow limits had to be maintained after

Parts used that are the only alloys produced at high temperatures, in particular the invention

especially at 200 to 300 ° C. Although alloys of all tested alloys were the one

ments of this type at temperatures in this range io satisfactory low degree of deformation during

have satisfactory properties, a processing is exhibited.

Improvement of the elongation properties at room temperatures. The artificial aging time and temperature depend on

temperature and a lower temperature increase the required service life and the operating

worth, in particular the yield point and temperature, which are provided for the workpiece

of creep resistance. 15 are. For operation at room temperature or

It has been found that the addition of 0.1 to moderately high temperatures will add 0.5 weight percent magnesium to alloys at temperatures between 170 and 200 ° C and for aluminum-based operation with 5 to 7% copper, 0.01 to 0 , 3% above 175 ⁰ C in the range 190-250 ⁰ C of titanium, 0.01 to 0.5% manganese, 0.1 to 0.35% silicon, stored. The artificial aging at temperatures from 0 to 0.5% silver, and not more than 0.4% iron, 20 above 210 ⁰ C is necessary, there is around the Kristallwobei the balance being aluminum, the mechanical grid so far to extend that no significant niche properties of the alloys in the kneaded dimensional changes under long-term acidic conditions at room temperature s "more considerable in the operation Depending on the type of production, by varying the alloy above the entire temperature range up to a content, in particular the magnesium content, 35O ° C. In addition, the alloys with magnesium addition can easily be achieved with argon within the ranges listed above. Preferred content ranges for all factory processes Use of base material pieces are 5.7 to 6.3% Copper, 0.05 to 0.15% titanium, or conventional welding rod materials, 0.1 to 0.3% manganese, 0.1 to 0.25% silicon, up to the point of welding. 0.4% iron, 0 to 0.05% nickel, zinc and chromium

The alloys can contain the usual impurities and optionally 0.2 to 0.4% silver. at

conditions such as one or more of these preferred alloys is in the case of

Elements nickel, chromium and zinc, contain, and forgings and extruded parts of magnesium '

although in an amount up to a total of 0.25%, and 35 content from 0.15 to 0.30% and in the case of rolled

Boron from 0 to 0.1%. Material (including sheet metal, strip and plate

Accordingly, the invention creates an aluminum with 0.25 to 0.4% magnesium. The rest is in

aluminum alloy, which contains the following elements in each case aluminum and the usual impurities

Percentage by weight contains: gungen.

pr r,,. - ₀ , 40 For forgings, extruded parts and sheet metal that

- ,. "Ρ ^er Qq, ^1s , · Q,„, are made of silver-free alloys and the

>, ⁿ _n ' _{ni,. n} 'o / foregoing preferred element regions aufMangan .... υ, υι pisup / o _we isen, is the optimal solution-

G. ^lum J ^{1,. 1} QJ ₀ / ^{/ o} at 525 to 535 ° C, and the optimal glow time depends

isen is 0 ^ _yon ^ _εΓ j _ewe jijg _en kneading form and cross-section thickness

Magnesium υ, ΐ to Up / 0 ^ _{üegt abef bd forgings and} extrusions

^ÖUDer - υ Dis up / 0 _{divide in the range of one ha} i _{ben and} 20 hours

The remaining amount consists of aluminum and clay and for sheets and strips for up to 8 hours

impurities. (preferably 5 minutes to 2 hours). After successful

The alloys are particularly suitable for airborne solution heat treatment and quenching will be the best engine parts and for aircraft covering parts and balance of mechanical properties in the -components that are exposed to high temperatures with long cases of sheet metal and extruded parts with space downtimes complex stress systems and higher temperatures after artificial aging have to stand. . for 8 to 24 hours at temperatures between

To get the possible advantages of the 55 190 and 200 ° C achieved according to the invention, in the case of forgings

continue to use manufactured alloys, ■■. during the same time, but at temperatures

the alloys must be up to between 210 and 220 ⁰ C after machining. If the silver-free

Solution annealed for 30 hours between 515 and 550 ⁰ C, alloys with higher magnesium contents used

quenched and then quenched for 5 to 36 hours; d. H. from 0.30 to 0.5% magnesium in the case

between 170 and 25O ⁰ C warm. 60 of forgings and extrusions and of

The workpiece can be melted in oil, water or 0.4 to 0.5% magnesium in the case of sheet metal and

zenem salt can be quenched. The cheapest strips, so a lower solution annealing

Strength properties are possessed by those parts that need a temperature of the order of 515 to 525 ° C.

were quenched in the quickest way, but manoeuvrable to avoid overheating that

Such a rapid quenching of an excessively high 65 is undesirable because it leads to the formation of bubbles

internal residual stress in certain components and thus the mechanical properties,

call forward. For these critical applications, the fatigue and creep resistance

therefore quenching in hot or boiling properties deteriorates. Overheating in

the microstructure of kneaded workpieces is not suitable for articles under high tension desirable, for example for covering and components for aircraft and aircraft engine parts. Even though the superheating, as stated above, by using lower solution heat treatment temperatures than can be avoided within the preferred range, this results in a decrease in mechanical Properties.

According to the invention it was found that the addition of 0.2 to 0.4% silver in the preferred alloys, as described above, an improvement in the mechanical properties of all Kneading effects. The addition of an additional amount of silver, on the other hand, reduces the Temperature at which the onset of overheating occurs and therefore acts in this relationship similar to magnesium.

Are silver-containing workpieces made of alloys of the preferred compositions in the case of forgings% to 20 hours in the inventive range solution treated at 515 to 535 ° C \\, quenched and aged 8 to 24 hours at 210 to 22O ⁰ C and in case of extrusion parts V _{solution annealed for 2} to 20 hours at 515 to 535 ° C, quenched and aged for 8 to 24 hours at 190 to 200 ° C, these parts have improved strength properties at room temperature and higher creep resistance at higher temperatures than the corresponding silverless alloys of the preferred compositions described above. The increase in the silver state beyond the preferred range, in particular to a content between 0.4 and 0.5% in forged and extruded parts, results in overheating when the solution heat treatment is carried out at 525 to 535.degree. To avoid overheating, the solution annealing temperature should be between 515 and 525 ° C. After subsequent quenching and artificial aging for 8 to 24 hours at 210 to 220 ^° C. or 190 to 200 ^° C. for forgings or extruded parts, this alloy has no advantage over an alloy containing 0.2 to 0.4% silver and _r y was heat-treated as according to the invention.

In the case of alloys of the preferred compositions containing sheets and strips of silver in the range according to the invention, overheating takes place during the solution heat treatment as early as 525 to 535 ° C., in contrast to the corresponding silver-free sheet. To avoid overheating, it is necessary to lower the solution heat treatment temperature to 520 to 530 ° C, while the annealing time is up to 8 hours (preferably 5 minutes to 2 hours). The sheets and strips are then quenched and aged for 8 to 24 hours at 175 to 185 ° C instead of 190 to 200 ° C for silver-free workpieces. Sheets and strips of the preferred silver-containing composition, the solution treated and at 520-530 ⁰ C were artificially aged at 175 to 185 ° C, have a higher 0,1-strength at room temperature to as sheets and strips of the preferred silver-free composition at 525 were solution to 535 ⁰ C and were artificially aged at 190 to 200 ⁰ C, while the creep resistance at high temperature is the same for both alloys. If the silver addition in sheet metal and strips is increased beyond the range according to the invention, in particular to 0.4 to 0.5%, then overheating occurs during the solution heat treatment at temperatures above 525.degree. To avoid such overheating, the solution annealing temperature would have to be lowered to 515 to 525 ° C. DieJ ^ lejjhe or .Streifen which contain 0.4 to 0.5% silver, and were solution annealed at 525 ° C to * and 515 were artificially aged at 175 to 185 ⁰ C, do not show any advantage in terms of strength properties at room temperature or the creep resistance at increased temperature compared to the sheets or strips with inventive silver content, which have been heat-treated under the preferred conditions described above.

The alloys produced according to the invention have particularly advantageous properties in terms of shape rolled sheets or strips. The sheets or strips of alloys according to the invention can one or both sides with a layer of commercially pure aluminum, or with an alloy, which consists of commercially pure aluminum and 0.8 to 1.2% zinc, or with a corrosion-resistant one Wrought alloy, consisting of 0.4 to 1.4% magnesium, 0.2 to 1.3% silicon, 0.0 to 1.0% Manganese, 0.0 to 0.3% chromium and 0.8 to 1.2% zinc, the remainder aluminum and the usual impurities and grain refining elements.

The following examples illustrate the improvement in elongation properties in space and elevated temperature and creep resistance of alloys made according to the invention became. The chemical composition of each alloy used in these tests is given in Table I indicated, the remainder in each case consisting of aluminum and usual impurities.

Table 1
Composition in percent by weight of the alloys used

alloy Cu Mn Fe Si Ti Mg Ag A. 6.0
5.95
5.90
6.0
5.96
6.07
5.82 0.27
0.26
0.26
0.26
0.25
0.27
0.25 0.16
0.16
0.18
0.18
0.16
0.23
0.16 0.12
0.11
0.19
0.16
0.16
0.17
0.14 0.17
0.15
0.12
0.14
0.15
0.13
0.16 o; 2o
0.34
0.21
0.21
0.02
0.20 ·· ■■ ·>: · ■ '^; . B. C. D. 0.29
0.49 E. - F. G

5 alloy Cu 1 483 228
continuation Fe Si 6th Ti Mg Ag H 6.0
5.91
5.88
5.95
6.07
6.08 Mn 0.16
0.15
0.14
0.20
0.15
0.15 0.15
0.18
0.18
0.11
0.15
0.18 0.14
0.12
0.12
0.13
0.13
0.14 0.31
0.32
0.33
0.02
0.20
0.33 I. 0.27
0.25
0.25
0.23
0.27
0.27 0.29
0.47 J κ L. M.

Alloys A to J were cast using the semi-continuous casting process, the alloys A to J and F to J were cast into round bars and rectangular slabs, respectively.

The ingots of alloys A through E were forged in the normal manner on ingots with a diameter of one inch. The bars were solution heat treated for 20 hours at 530 ⁰ C, as far as in the various tables indicated otherwise, quenched in boiling water and then artificially aged for 16 hours at 215 ° C. Appropriate test pieces were cut from the forged bars in each of the alloys and machined and tested at room and elevated temperature for elongation, creep resistance and fatigue resistance as set out in Tables 2, 3 and 4. The results of these tests are also shown in FIG included in these tables.

table

Forged rod

Alloy A

0.1% limit

kp / cm ²

Tensile strength kp / cm ²

Elongation alloy B

0.1% limit
kp / cm ²

Tensile strength kp / cm ²

strain

Alloy C

0.1% limit kp / cm ²

Tensile strength kp / cm ²

strain

Strength at room temperature
Strength at 150 ⁰ C after
200 hours of exposure to this

temperature

Strength at 200 ⁰ C after
200 hours exposure dLse <
temperature

2460

2250

1465

3940

3310

2270

3640

3290

2020

4790

4070

2570

3750 *)

4650 *)

16

20th

Creep stress in kp / cm ² for 0.1% total, plastic creep deformation at 200 ° C

in 100 hours

in 1000 hours

Leakage in kp / cm ² for 0.1% of total, plastic creep deformation at 25O ⁰ C

in 100 hours

in 1000 hours _;

Total plastic creep deformation in% at 200 ° C and 1575 kp / cm ² creep stress
in 100 hours

992 788

567 441

broken after 105 hours 1770 1480

1040 615

in 500 hours.
in 1000 hours

0.045

0.081 0.114

0.046 *)

0.172 *) broken after 960 hours *)

Half range of tension in kp / cm ² Door break after 100,000 cycles as a rotating cantilever

at room temperature

at 200 ° C

at 300 ° C

1940 1795 1420 2650 2270 1795

552

*) These samples with 0.34% magnesium were solution heat treated at 520 ° C for 20 hours instead of 530 ° C like the alloys A and B, quenched in boiling water and aged for 16 hours at 215 ° C because the solution heat treatment of alloy C led to significant overheating of the microstructure at 530 ° C.

The improvement of the stress properties at room and elevated temperature as well as the creep resistance, which have been exhibited by alloy B and recorded according to the invention were obtained from comparing the test results this alloy with those of alloy A. The apparent advantage of the 0.1% limit at room temperature, which alloy C has in comparison to alloy B, is determined by the The deterioration in the creep stress of the former alloy is canceled.

The reduction in the 0.1% limit and the tensile strength at room temperature and the creep strength at 200 ^° C. resulting from the solution heat treatment

forged bars of the preferred alloy B at a temperature of 52o C ⁰ arise that is below the preferred range 525-535 ⁰ C, it is clear from the examination of the test results which are listed in Table 3 below.

Table 4 contains the strength properties at room temperature and the results of the creep tests carried out at 200 ° C. on forging bars made from alloy B and in the two silver-containing alloys D and E. These tests were performed on two bars sets solution treated for 20 hours at 520 ⁰ C and 53o ° C, quenched in boiling water and were incubated for 16 hours then artificially aged at 215 ° C.

Table 3 Forged rod made of. Alloy B Solution heat treatment for 20 hours at 52O ⁰ C, tensile strenght strain Solution heat treatment for 20 hours tensile strenght 53O ° C, ■ Quenching in boiling water kp / cm ² ..% Deterrent in boiling kp / cm ² water Artificial aging 16 hours at 215 ° C 4570 9.5 Artificial aging 16 hours at 4790 215 ⁰ C Strength at room temperature ... 0.1% limit 0.067 0.1% limit 0.045 .Strain Total plastic creep kp / cm ² 0.148
0.297 _____ kg / cm ² 0.081
0.114 % deformation in% at 200 ° C
and 1575 kgf / cm ² creep
voltage 3560 3640 8th Half range of tension 100 hours in kp / cm ² for breakage after 500 hours
1000 hours 2140 2270 100,000 cycles as rotating Cantilever at 200 ° C

table

Forged rod after solution annealing,
Quenching in boiling water and
16 hours artificial aging at 215 ^° C I.
0.1 -% -
border
kp / cm ² Deh
tion
% L.
0.1 -% -
border
kp / cm ² sgierung D
train
strength
kp / cm ² Deh
tion
% Le
0.1 -% -
border
kp / cm ² ejerung E
train
strength
kp / cm ² Deh
tion
% Solution heat treatment for 20 hours at 520 ° C 3560 4570 ' 9.5 3820 4690 8th 3890 4600 6th Solution annealing 20 hrs. At 530 ⁰ C 3640 4790 8th 4030 4800 6th overheating in the
Micro structure 0.067 0.023 0.034 Solution Heat 20 hrs. At 530 ⁰ C 0.045 0.037 overheating in the
Micro structure 0.148 0.069 0.088 Solution heat treatment for 20 hours at 530 ° C 0.081 0.100 overheating in the
Micro structure .alloy B
train
strength
kp / cm ² Solution Heat 20 hrs. At 520 ⁰ C Solution heat treatment for 20 hours at 520 ° C Strength at room temperature Total plastic creep
deformation in%
100 hours at 200 ^° C. and
1575 kgf / cm ² creep stress Total plastic creep
deformation in%
500 hours at 200 ° C and
1575 kgf / cm ² creep stress

109 512/134

The benefit of the 0.1 -% - strength at room temperature and the creep resistance at 200 ° C by the addition of 0.29% silver belongs, which is supplied to the forging ingot containing magnesium in the preferred range, and solution heat treated at 520 ⁰ C is clear from a comparison of the test results reported in Table 4 for Alloy D under these conditions with those for Alloy B which was solution heat treated at either 520 or 530 ° C. The advantage of solution annealing of the silver-free alloy B at 530 ° C is therefore obvious on the basis of the results given in the same table. In the case of alloy E, which contains 0.21% magnesium and 0.49% silver, the microstructure of the forging bar showed that overheating took place during solution heat treatment at 530 ° C., but that the structure took place for 20 hours after solution heat treatment showed no signs of overheating at 520 ° C.

Heavy rolled plates made from alloys F to J were clad on both sides with sheets made from an AlZn alloy with V / o zinc, the thickness of the cladding plates making up 5% of the Kerrible sheet. The lined panels were preheated and hot rolled in the normal manner to about 6.3 mm thick and then cold rolled to 1.6 mm with several intermediate anneals. Sample sheets in alloy F, G and H were solution-annealed in a salt bath, quenched in cold water for 30 minutes at 530.degree. C. and dressed. As detailed in Table 6, sheets of alloys I and J were solution annealed at 525 and 520 ° C, respectively. The sheets of the silver-free alloys, the alloys F, G and H, were artificially aged at 195 ° C. for 16 hours, while the sheets containing silver, the alloys I and J, were artificially aged at 180 ° C. for 16 hours. Additional sheets of alloy H were solution annealed at 530 ° C., quenched and artificially aged for 16 hours at 180 ° C. for comparison purposes.

Appropriate test sections were made from each alloy in the transverse direction from any location in the sheet taken and processed into suitable test pieces. The patterns were then used for space and at elevated temperature checked for elongation and according to the lists in Tables 5_ and 6 Tested for creep resistance. The results of this test of the silver-free and silver-containing alloys are listed in Tables 5 and 6.

Table 5

Sheet metal clad with Al + 1% Zn

Alloy F

0.1% limit
kp / cm ²

Tensile strength kp / cm ²

strain

Alloy G

0.1% limit

kp / cm ²

tensile strenght
kp / cm ²

strain

Alloy H

0.1% limit
kp / cm ²

tensile strenght
kp / cm ²

strain

Strength at room temperature

Strength at 150 ° C
400 hours of storage at
this temperature

2440

3670

10

3280

4190

3530

4480

2000

2820

16

2840

3470

3020

3730

Strength at room temperature
after 400 hours of aging
at 15O ⁰ C ...-

2380

3700

12th

3320

4220

3420

4440

Total plastic creep strain in% after 100 hours.
at 175 ° C and 1575 kgf / cm ²
Creep stress

2.3

0.10

0.043

Total plastic creep strain in% after 1000 hours.
at 130 ° C and 2050 kp / cm ²
Creep stress

broken after 900 hours 0.060

0.039

table

Alloy H Train-
strength
kp / cm ² Deh
tion 0.067 4480 9.5 0.043 Alloy I. train
strength
kp / cm ² Deh
tion 0.046 Alloy J train
strength
kp / cm ² Deh
tion 0.042 Sheet metal clad with Al + 1% Zn Solution heat treatment 30 min.
at 53O ° C,
deterrence
in cold water,
16 hours at 180 ^° C
Artificial aging 4520 9 Solution annealing
30 min at 530 ° C
Quenching in
cold water
16 hours at 195 ° C
Artificial aging Solution heat treatment 30 min.
at 525 ° C,
Scare off
in cold water,
16 hr. At 18O ⁰ C
Artificial aging 4535 9.5 Solution heat treatment 30 min.
at 52O ⁰ C,
Scare off
in cold water,
16 hr. At 18O ⁰ C
Artificial aging .4460 m 9.5 0.1 -% -
border
kp / cm ² 3530 0.1 -% -
border
kp / cm ² 0.1 -% -
border
kp / cm ² Strength at room temperature 3640 3750 3730 Total plastic creep
elongation (%) after 100 hours
. at. 175 ⁰ C and 1575 kgf / cm ²
Creep stress Strength at room temperature Total plastic creep
elongation (%) after 100 hours
at 175 ° C and 1575 kgf / cm ²
Creep stress

The improvement of the elongation properties at room temperature and elevated temperature and des Creep resistance caused by the addition of 0.20 and 0.31% magnesium, the sheets produced according to the invention was added and the superiority of the sheet with a magnesium content within the preferred range given above, namely 0.25 to 0.4% magnesium, is when comparing the values in Table 5 for cladding panels of alloys F, G and H obvious.

The alloy sheets containing silver, alloys I and J, were solution annealed at 525 and 520 ° C, respectively. because there was overheating in the microstructure and blistering on the surface the few sheets found that were solution annealed at higher temperatures. A Comparison of the test results given in Table 6 for Alloy I sheets obtained at 180 ° C artificially aged with that of the corresponding silver-free alloy, alloy H, the artificially aged at the preferred temperature of the latter alloy, 195 ° C the advantage of the 0.1% limit at room temperature of the addition of 0.29% silver, which corresponds to that according to the invention was added while maintaining the same high level of creep resistance would. Increasing the silver content on the sheet to 0.47%, as with alloy J, gives one property level similar to that of alloy I.

Alloys K, L and M were semicontinuously cast into round billets and hot extruded in the normal manner to give billets 25.4 mm in diameter. Sample lengths of ingots from each alloy were solution annealed for 5 hours at 530 ° C, quenched in cold water and artificially aged for 16 hours at 195 ° C, with another length made of alloy L being artificially aged at 185 ° C for 16 hours after solution annealing and deterrence. - A further length of alloy M was solution for 5 hours at 520 ° C followed by quenching in cold water and artificial aging for 16 hours at 195 ⁰ C. Suitable oblong test pieces were machined from the ingots in the various conditions of the heat compensation and elongation and creep property, which were tested at room temperature and 175 ° C, respectively, as shown in Table 7, which also shows the test results.

table

Extruded rod
with a diameter of about 25 mm Alloy K
Solution annealing
5 hours at 530 "C,
deterrence
in cold water,
Outsourcing
16 hours at 195 ° C train
strength
kp / cm ² Deh
tion
% 0.086 - Alloy L
Solution annealing
5 hours at 530 ° C,
deterrence
in cold water,
Outsourcing
16 hours at 195 ° C train
strength
kp / cm ² Deh
tion
% 0.033 4915 15th Alloy M *)
Solution annealing
5 hours at 520 ° C,
deterrence
in cold water,
Outsourcing
16 hours at 195 ° C train
strength
kp / cm ² Deh
tion
% 0.038 0.1 -% -
border
kp / cm ² 4380 14th 0.1 -% -
border
kp / cm ² 4975 13th Alloy L
Solution annealing
5 hours at 53D "C
Deterrence in
cold water
Outsourcing
16 hours at 185 ° C 0.060 0.1 -% -
border
kp / cm ² 4790 "■ ' 15th *) For the during
* 5 hours at 530 ⁰ C.
through solution
glow treated,
0.33% magnesium
containing samples
occurred considerable
Overheating on,
at 520 ⁰ C through
Solution heat treatment Strength at room temperature 3170 - 4140 4070 treated samples
however it wasn't
such appearance
verifiable. Total plastic creep
deformation in%
100 hours at 175 ° C and
1575 kp / cm ² creep stress 4140 '· - Strength at room temperature Total plastic creep
deformation in%
100 hours at 175 ° C and
1575 kgf / cm ² creep stress

*) Significant overheating took place in the samples, which contained 0.33% magnesium, solution annealed for 5 hours at 530 ° C but no trace was found in the microstructures of the test pieces which were solution heat treated at 520 ° C.

The improvement of the elongation properties at room temperature and the creep resistance at elevated temperature obtained on the extrusion billet containing 0.20% magnesium and was produced according to the invention is evident when comparing the results for the alloys K. and L. Increasing the magnesium content to 0.33%, as with alloy M, gave the same result Strength properties as with alloy L. The advantage in creep resistance at 175 ° C, the was achieved by artificial aging of alloy L for 16 hours at 195 ° C, which is the preferred Represents tempering in comparison to artificial aging for 16 hours at 185 ° C, results clearly from this table, although there is no difference in the elongation properties at room temperature is available.

Claims (2)

60 claims: 1. Wrought aluminum alloy with high creep strength, consisting of 5 to 7% copper 0.01 to 0.3% titanium 0.01 to 0.5% manganese 0.1 to 0.35% silicon 0.1 until 0.5% magnesium out 6.3% copper 0 until 0.4% iron until 0.15% titanium 0 until 0.5% silver until 0.3% manganese The rest of the aluminum with the usual impurities until 0.25% silicon worked.
2. Aluminum alloy according to claim 1, be until 0.4% magnesium standing until 0.4% iron 5.7 until 0.05% nickel 0.05 until 0.05% zinc 0.1 until 0.05% chrome 0.1 until The rest of the aluminum with the usual impurities 0.15 0 0 0 0 worked. 3. Aluminum alloy according to claim 2, characterized by an additional content of 0.2 to 0.4% silver. 4. Use of an aluminum alloy according to claim 1 for producing a kneaded one Workpiece. 5. Verv / end of an aluminum alloy according to claim 2 or 3 with a magnesium content from 0.15 to 0.3% for the production of forged or extruded workpieces. 6. Use of an aluminum alloy according to claim 2 or 3 with a magnesium content from 0.25 to 0.4% for the production of rolled sheet or strip. 7. A method for the heat treatment of a workpiece according to claim 4, characterized in that the workpiece after kneading for a period of up to 30 hours at 515 to 55O ⁰ C, preferably in water, oil or molten salt, quenched and then during 5 is artificially aged to 36 hours at 170 to 250 ⁰ C. 8. A method for the heat treatment of a workpiece according to claim 5, characterized in that that the workpiece after kneading for a period of half to 20 hours between 525 and 535 ⁰ C solution annealed, preferably in water, Ul or molten salt, quenched and then, preferably for 8 to 24 hours between 210 and 220 ⁰ C for forged workpieces and between 190 and 200 ⁰ C for extruded workpieces, is artificially aged. 9. A method for the heat treatment of a rolled sheet or strip according to claim 6, characterized in that the workpiece after kneading for up to 8 hours, preferably 5 minutes to 2 hours, at 525 to 535 ° C for silver-free workpieces and at 520 to 53O ⁰ C for silver-containing workpieces, solution annealed, preferably in water, oil or molten salt, 'quenched and then, preferably for the duration of 8 to 24 hours 190 to 200 ⁰ C for silver-free workpieces and at 175 to 185 ° C for silver-containing workpieces, is artificially aged. 109 512/134