EP2270249B2 - AlMgSi-sheet for applications with high shaping requirements - Google Patents

Description

The invention relates to a method for producing a strip from an AlMgSi alloy, in which a rolled bar is cast from an AlMgSi alloy, the rolled bar is subjected to homogenization, the rolled bar is brought to the rolling temperature and then optionally cold-rolled to its final thickness. In addition, the invention relates to an aluminum strip made of an AlMgSi alloy and its advantageous use.

Above all in motor vehicle construction, but also in other fields of application, for example aircraft construction or rail vehicle construction, sheets of aluminum alloy are required which are not only distinguished by particularly high strength values, but at the same time have very good forming behavior and enable high degrees of forming. Typical areas of application in motor vehicle construction are the body and chassis parts. In the case of visible, painted components, for example body panels that are visible from the outside, there is also the fact that the materials must be reshaped in such a way that the surface after painting is not affected by defects such as flow figures or roping. This is particularly important, for example, for the use of aluminum alloy sheets for the production of bonnets and other body components in a motor vehicle. However, it limits the choice of materials with regard to aluminum alloy. AlMgSi alloys in particular, the main alloy components of which are magnesium and silicon, have relatively high strengths with good forming behavior and excellent corrosion resistance. AlMgSi alloys are the AA6XXX alloy types, for example the AA6016, AA6014, AA6181, AA6060 and AA6111 alloy types. Aluminum strips are usually produced from an AlMgSi alloy by casting a rolling bar, homogenizing the rolling bar, hot rolling the rolling bar and cold rolling the hot strip. The billet is homogenized at a temperature of 380 to 580 ° C for more than one hour. The strips can be delivered in condition T4 by a final solution annealing with subsequent quenching and cold aging at room temperature for at least three days. Condition T6 is set after quenching by hot aging at temperatures between 100 ° C and 220 ° C.

US-4808247A discloses a process for producing aluminum strip from an AlSiMg alloy, the final hot rolling temperature being not more than 350 ° C. In the example, a cold-rolled sheet in state T4 has a yield strength of 109 MPa and an elongation at break of 32%.

EP-1533394 A discloses a hot and cold rolled aluminum strip made of AA6016, which has a yield strength of 115 MPa and an elongation at break A ₈₀ of 25.4% in state T4.

It is problematic that coarse Mg ₂ Si precipitates are present in hot-rolled aluminum strips made of AlMgSi alloys, which are broken and reduced in the subsequent cold rolling by high degrees of deformation. Hot strips of an AlMgSi alloy are usually produced in thicknesses from 3 mm to 12 mm and fed to cold rolling with high degrees of deformation. Since the temperature range in which the AlMgSi phases form is run very slowly in conventional hot rolling, these phases form very roughly. The temperature range for the formation of the above phases depends on the alloy but is between 550 ° C and 230 ° C. It could be demonstrated experimentally that these rough phases in the hot strip negatively influence the elongation of the end product. This means that the forming behavior of aluminum strips made of AlMgSi alloys has not yet been fully exploited.

The present invention is therefore based on the object of providing a method for producing an aluminum strip from an AlMgSi alloy and an aluminum strip which has a higher elongation in the T4 state and, in this respect, enables higher degrees of deformation in the production of structural components, for example. In addition, the present invention is based on the object of proposing advantageous uses of a sheet made from the aluminum strip according to the invention.

The object is achieved with a method having the features of patent claim 1. According to the invention, the hot strip has a temperature of at most 130 ° C., preferably a temperature of at most 100 ° C., immediately after it has left the last hot rolling pass and is wound up with this or a lower temperature.

It has been shown that the size of the Mg ₂ Si precipitates in a hot strip of an AlMgSi alloy can be significantly reduced by quenching, ie by accelerated cooling. Due to the rapid cooling from a hot strip temperature between 230 ° C and 550 ° C to a maximum of 130 ° C, preferably a maximum of 100 ° C at the outlet of the last hot rolling pass, the structural condition of the hot strip is frozen so that coarse precipitates can no longer form. After solution annealing and quenching to the final thickness, the resulting aluminum strip has a significantly improved elongation with the usual strengths in state T4 and an identical or even improved hardenability to state T6. This combination of properties has not been achieved with strips made of AlMgSi alloys.

According to an advantageous embodiment of the method according to the invention, this cooling process takes place within the last two hot rolling passes, i.e. cooling to 130 ° C and less takes place within seconds, maximum within five minutes. It has been shown that with this procedure, the increased elongation values with the usual strength or elongation limit values in state T4 and the improved hardenability in state T6 can be achieved in a particularly reliable manner.

According to the invention, a particularly economical implementation of the method is achieved in that the hot strip itself is quenched to the winding temperature using at least one sinker cooler and the hot rolling passes applied with emulsion. A circuit board cooler consists of an arrangement of coolant or lubricant nozzles which spray a rolling emulsion onto the aluminum strip. The blank cooler is often used in a hot rolling mill to cool rolled hot strips to rolling temperature and adjust the winding temperature before hot rolling. The method according to the invention can thus be used on conventional systems without special additional devices. By definition, the hot rolling temperature is above the recrystallization temperature of a metal, i.e. above 230 ° C for aluminum. According to the teaching of the present invention, the winding temperature is 130 ° C but clearly below these standard process conditions.

If the hot rolling temperature of the hot strip before the penultimate hot rolling pass is at least 230 ° C., preferably above 400 ° C., according to a next embodiment of the method according to the invention it is achieved that particularly small Mg ₂ Si precipitates are present in the quenched hot strip, since the largest proportion of the alloy components Magnesium and silicon are present in dissolved form in the aluminum matrix at these temperatures. This advantageous condition of the hot strip is quasi "frozen" by quenching.

The thickness of the finished hot strip is 3 mm to 12 mm, preferably 3.5 mm to 8 mm, so that conventional cold rolling stands can be used for cold rolling.

The aluminum alloy used is preferably of the type AA6xxx, preferably AA6014, AA6016, AA6060, AA6111 or AA6181. All AA6xxx alloy types have in common that they have a particularly good forming behavior, characterized by high elongation values in state T4 and very high strengths or yield limits in operating state T6, for example after hot aging at 205 ° C / 30 min.

$$\mathrm{1}\mathrm{,0}\%\le \mathrm{Si}\le \mathrm{1}\mathrm{,5}\%,$$

$$\mathrm{Fe}\le \mathrm{0,5}\%,$$

$$\mathrm{Cu}\le \mathrm{0,2}\%,$$

$$\mathrm{Mn}\le \mathrm{0,2}\%,$$

$$\mathrm{Cr}\le \mathrm{0,1}\%,$$

$$\mathrm{Zn}\le \mathrm{0,1}\%,$$

$$\mathrm{Ti}\le \mathrm{0,1}\%$$

und Rest Al sowie unvermeidbare Verunreinigungen maximal in Summe 0,15 %, einzeln maximal 0,05 %.An aluminum alloy of type AA6016 has the following alloy components in percent by weight: $$0.25\%\le \mathrm{Mg}\le 0.6\%,$$

$$\mathrm{1}\mathrm{,\; 0}\%\le \mathrm{Si}\le \mathrm{1}\mathrm{,\; 5th}\%,$$

$$\mathrm{Fe}\le 0.5\%,$$

$$\mathrm{Cu}\le 0.2\%,$$

$$\mathrm{Mn}\le 0.2\%,$$

$$\mathrm{Cr}\le 0.1\%,$$

$$\mathrm{Zn}\le 0.1\%,$$

$$\mathrm{Ti}\le 0.1\%$$

and the remainder Al as well as unavoidable impurities in total 0.15% maximum, individually maximum 0.05%.

With magnesium contents of less than 0.25% by weight, the strength of the aluminum strip, which is intended for structural applications, is too low; on the other hand, the formability deteriorates with magnesium contents above 0.6% by weight. In combination with magnesium, silicon is essentially responsible for the hardenability of the aluminum alloy and thus also for the high strengths that can be achieved in the application, for example, after a paint bake. With Si contents of less than 1.0% by weight, the hardenability of the aluminum strip is reduced, so that only reduced strengths are provided in the application can. Si contents of more than 1.5% by weight, however, lead to casting problems with regard to the production of the billet. The Fe content should be limited to a maximum of 0.5% by weight in order to prevent coarse precipitations. Limiting the copper content to a maximum of 0.2% by weight leads above all to an improved corrosion resistance of the aluminum alloy in the specific application. The manganese content of less than 0.2% by weight reduces the tendency to form coarser manganese deposits. Chromium ensures a fine structure, but should be limited to 0.1% by weight in order to avoid coarse precipitations. The presence of manganese, on the other hand, improved the weldability by reducing the tendency to crack or the sensitivity to quenching of the aluminum strip according to the invention. A reduction in the zinc content to a maximum of 0.1% by weight improves in particular the corrosion resistance of the aluminum alloy or of the finished sheet in the respective application. In contrast, titanium ensures grain refinement during casting, but should be limited to a maximum of 0.1% by weight in order to ensure good castability of the aluminum alloy.

$$\mathrm{0,3}\%\le \mathrm{Si}\le \mathrm{0,6}\%,$$

$$\mathrm{0,1}\%\le \mathrm{Fe}\le \mathrm{0,3}\%$$

$$\mathrm{Cu}\le \mathrm{0,1}\%,$$

$$\mathrm{Mn}\le \mathrm{0,1}\%,$$

$$\mathrm{Cr}\le \mathrm{0,05}\%,$$

$$\mathrm{Zn}\le \mathrm{0,10}\%,$$

$$\mathrm{Ti}\le \mathrm{0,1}\%$$

und
Rest Al sowie unvermeidbare Verunreinigungen maximal in Summe 0,15 %, einzeln maximal 0,05 %.An aluminum alloy of type AA6060 has the following alloy components in percent by weight: $$0.35\%\le \mathrm{Mg}\le 0.6\%,$$

$$0.3\%\le \mathrm{Si}\le 0.6\%,$$

$$0.1\%\le \mathrm{Fe}\le 0.3\%$$

$$\mathrm{Cu}\le 0.1\%,$$

$$\mathrm{Mn}\le 0.1\%,$$

$$\mathrm{Cr}\le 0.05\%,$$

$$\mathrm{Zn}\le 0.10\%,$$

$$\mathrm{Ti}\le 0.1\%$$

and
Remainder Al as well as unavoidable impurities maximum 0.15% in total, individually maximum 0.05%.

The combination of a precisely specified magnesium content with a reduced Si content compared to the first embodiment and a narrowly specified Fe content results in an aluminum alloy in which the formation of Mg ₂ Si precipitates after hot rolling can be prevented with the method according to the invention, so that a sheet with improved elongation and high yield strengths can be provided in comparison to conventionally produced sheets. The lower upper limits of the alloy components Cu, Mn and Cr additionally reinforce the effect of the method according to the invention. With regard to the effects of the upper limit of Zn and Ti, reference is made to the comments on the first embodiment of the aluminum alloy.

$$\mathrm{0,3}\%\le \mathrm{Si}\le \mathrm{0,6}\%,$$

$$\mathrm{Fe}\le \mathrm{0,35}\%$$

$$\mathrm{Cu}\le \mathrm{0,25}\%,$$

$$\mathrm{0,05}\%\le \mathrm{Mn}\le \mathrm{0,20}\%,$$

$$\mathrm{Cr}\le \mathrm{0,20}\%,$$

$$\mathrm{Zn}\le \mathrm{0,10}\%,$$

$$\mathrm{0,05}\%\le \mathrm{V}\le \mathrm{0,20}\%,$$

$$\mathrm{Ti}\le \mathrm{0,1}\%$$

und
Rest Al sowie unvermeidbare Verunreinigungen maximal in Summe 0,15 %, einzeln maximal 0,05 %.An aluminum alloy of type AA6014 has the following alloy components in percent by weight: $$0.4\%\le \mathrm{Mg}\le 0.8\%,$$

$$0.3\%\le \mathrm{Si}\le 0.6\%,$$

$$\mathrm{Fe}\le 0.35\%$$

$$\mathrm{Cu}\le 0.25\%,$$

$$0.05\%\le \mathrm{Mn}\le 0.20\%,$$

$$\mathrm{Cr}\le 0.20\%,$$

$$\mathrm{Zn}\le 0.10\%,$$

$$0.05\%\le \mathrm{V}\le 0.20\%,$$

$$\mathrm{Ti}\le 0.1\%$$

and
Remainder Al as well as unavoidable impurities maximum 0.15% in total, individually maximum 0.05%.

$$\mathrm{0,8}\%\le \mathrm{Si}\le \mathrm{1},2\%,$$

$$\mathrm{Fe}\le \mathrm{0,45}\%,$$

$$\mathrm{Cu}\le \mathrm{0,10}\%,$$

$$\mathrm{Mn}\le \mathrm{0,15}\%,$$

$$\mathrm{Cr}\le \mathrm{0,10}\%,$$

$$\mathrm{Zn}\le \mathrm{0,20}\%,$$

$$\mathrm{Ti}\le \mathrm{0,1}\%$$

und Rest Al sowie unvermeidbare Verunreinigungen maximal in Summe 0,15 %, einzeln maximal 0,05 %.An aluminum alloy of type AA6181 has the following alloy components in percent by weight: $$0.6\%\le \mathrm{Mg}\le \mathrm{1},0\%,$$

$$0.8\%\le \mathrm{Si}\le \mathrm{1},\mathrm{2nd}\%,$$

$$\mathrm{Fe}\le 0.45\%,$$

$$\mathrm{Cu}\le 0.10\%,$$

$$\mathrm{Mn}\le 0.15\%,$$

$$\mathrm{Cr}\le 0.10\%,$$

$$\mathrm{Zn}\le 0.20\%,$$

$$\mathrm{Ti}\le 0.1\%$$

and the remainder Al as well as unavoidable impurities in total 0.15% maximum, individually maximum 0.05%.

$$\mathrm{0,7}\%\le \mathrm{Si}\le \mathrm{1},1\%,$$

$$\mathrm{Fe}\le \mathrm{0,40}\%$$

$$\mathrm{0,50}\%\le \mathrm{Cu}\le \mathrm{0,90}\%,$$

$$\mathrm{0,15}\%\le \mathrm{Mn}\le \mathrm{0,45}\%,$$

$$\mathrm{Cr}\le \mathrm{0,10}\%,$$

$$\mathrm{Zn}\le \mathrm{0,15}\%,$$

$$\mathrm{Ti}\le \mathrm{0,1}\%$$

und
Rest Al sowie unvermeidbare Verunreinigungen maximal in Summe 0,15 %, einzeln maximal 0,05 %. Die Legierung AA6111 zeigt grundsätzlich augrund des erhöhten Kupfergehaltes höhere Festigkeitswerte im Einsatzzustand T6, ist aber als korrosionsanfälliger anzustufen.An aluminum alloy of type AA6111 has the following alloy components in percent by weight: $$0.5\%\le \mathrm{Mg}\le \mathrm{1},0\%,$$

$$0.7\%\le \mathrm{Si}\le \mathrm{1},1\%,$$

$$\mathrm{Fe}\le 0.40\%$$

$$0.50\%\le \mathrm{Cu}\le 0.90\%,$$

$$0.15\%\le \mathrm{Mn}\le 0.45\%,$$

$$\mathrm{Cr}\le 0.10\%,$$

$$\mathrm{Zn}\le 0.15\%,$$

$$\mathrm{Ti}\le 0.1\%$$

and
Remainder Al as well as unavoidable impurities maximum 0.15% in total, individually maximum 0.05%. The AA6111 alloy generally shows higher strength values in the T6 operating condition due to the increased copper content, but is to be classified as more susceptible to corrosion.

All of the aluminum alloys shown are specifically adapted to different applications in their alloy components. As already stated, they show particularly high elongation values in state T4 combined with a particularly pronounced increase in the yield strength, for example after aging at 205 ° C./30 minutes.

According to a second teaching of the present invention, the object shown above is achieved by an aluminum strip consisting of an AlMgSi alloy, in that the aluminum strip in state T4 has an elongation at break A ₈₀ of at least 30% with a yield strength Rp0.2 of 80 to 140 MPa having. The delivery state T4 is usually achieved by solution annealing with quenching and subsequent storage at room temperature for at least three days, since the properties of the solution-annealed sheets or strips are then stable. The combination of elongation at break A ₈₀ and proof stress Rp0.2 of the aluminum strip according to the invention has not been achieved with previously known AlMgSi alloys. The aluminum strip according to the invention therefore enables maximum degrees of deformation due to the high elongation values with maximum values for the yield point Rp0.2 in the finished sheet metal or component.

The aluminum strip according to the invention preferably has a yield strength Rp0.2 of more than 185 MPa with an elongation A ₈₀ of at least 15% in state T6, that is to say in the operating state or application state. These values were measured for aluminum strips produced in accordance with the invention in the state T6, which had undergone hot aging at 205 ° C./30 minutes after solution annealing and quenching (state T4). Because of the high yield strengths in state T6 with very good elongation values in state T4, the aluminum strip according to the invention is particularly well suited, for example, for use in motor vehicle construction.

According to a further embodiment of the invention, the solution-annealed and quenched aluminum strip has a proof stress difference ΔRp0.2 between state T6 and T4 of at least 80 MPa in state T6 after being aged at 205 ° C./30 min. The increase in the proof stress from state T4 to state T6 is particularly high in the aluminum strip according to the invention. The aluminum strip according to the invention can therefore be reshaped very well in the state T4 and can then be put into a high-strength operating state (state T6) by hot aging. Given the necessary, complex shapes and the required high strength values or expansion limits, for example in motor vehicle construction, good hardenability is particularly advantageous for the production of complex components.

The aluminum strips preferably have a thickness of 0.5 mm to 12 mm. Aluminum strips with thickness 0.5 mm to 2 mm are preferably used for body parts, for example in motor vehicle construction, while aluminum strips with greater thicknesses of 2 to 4.5 mm are used, for example, in chassis parts in motor vehicle construction. Individual components can also be manufactured in cold strip with a thickness of up to 6 mm. In addition, aluminum strips with a thickness of up to 12 mm can be used in specific applications. These very thick aluminum strips are usually only provided by hot rolling.

According to a further embodiment of the aluminum strip according to the invention, the aluminum alloy of the aluminum strip is of the type AA6xxx, preferably AA6014, AA6016, AA6060, AA6111 or AA6181. With regard to the advantages of these aluminum alloys, reference is made to the explanations regarding the method according to the invention.

Due to the excellent combination of good formability in state T4, high corrosion resistance and high values for the yield strength Rp0.2 in the operating state (state T6), the above-mentioned object is achieved according to a third teaching of the present invention by using a sheet made from an aluminum strip according to the invention solved as a component, chassis or structural part and sheet metal in motor vehicle, aircraft or rail vehicle construction, in particular as a component, chassis part, outer or inner plate in motor vehicle construction, preferably as a body component. Visible body parts in particular, such as bonnets, fenders, etc., as well as outer skin parts of a rail vehicle or aircraft benefit from the high yield strengths Rp0.2 with good surface properties even after forming with high degrees of deformation.

There are now a multitude of possibilities for designing and developing the method according to the invention and the aluminum strip according to the invention and the use of a sheet made therefrom. For this purpose, reference is made on the one hand to the claims subordinate to claims 1 and 6 and to the description of exemplary embodiments in conjunction with the drawing.

The drawing shows in the only one Figure 1 a schematic flow diagram of an embodiment of the method according to the invention for producing a strip from an AlMgSi aluminum alloy with the steps a) producing and homogenizing the rolling ingot, b) hot rolling, c) cold rolling and d) solution annealing with quenching.

$$\mathrm{0,3}\%\le \mathrm{Si}\le \mathrm{0,6}\%,$$

$$\mathrm{0,1}\%\le \mathrm{Fe}\le \mathrm{0,3}\%$$

$$\mathrm{Cu}\le \mathrm{0,1}\%,$$

$$\mathrm{Mn}\le \mathrm{0,1}\%,$$

$$\mathrm{Cr}\le \mathrm{0,05}\%,$$

$$\mathrm{Zn}\le \mathrm{0,1}\%,$$

$$\mathrm{Ti}\le \mathrm{0,1}\%$$

und
Rest Al sowie unvermeidbare Verunreinigungen maximal in Summe 0,15 %, einzeln maximal 0,05 %.First, a billet 1 is cast from an aluminum alloy with the following alloy components in percent by weight: $$0.35\%\le \mathrm{Mg}\le 0.6\%,$$

$$0.3\%\le \mathrm{Si}\le 0.6\%,$$

$$0.1\%\le \mathrm{Fe}\le 0.3\%$$

$$\mathrm{Cu}\le 0.1\%,$$

$$\mathrm{Mn}\le 0.1\%,$$

$$\mathrm{Cr}\le 0.05\%,$$

$$\mathrm{Zn}\le 0.1\%,$$

$$\mathrm{Ti}\le 0.1\%$$

and
Remainder Al as well as unavoidable impurities maximum 0.15% in total, individually maximum 0.05%.

The rolled bar produced in this way is homogenized in a furnace 2 at a homogenization temperature of approximately 550 ° C. for 8 h, so that the alloying alloy components present are particularly homogeneously distributed in the rolled bar, Fig 1a ).

In Fig 1b ) shows how the billet 1 is reversibly hot-rolled by a hot rolling stand 3 in the present exemplary embodiment of the method according to the invention, the billet 1 having a temperature of 230 to 550 ° C. during hot rolling. In this exemplary embodiment, the hot strip 4 preferably has a temperature of at least 400 ° C. after leaving the hot rolling stand 3 and before the penultimate hot rolling pass. At this hot strip temperature of at least 400 ° C., the hot strip 4 is preferably quenched using a blank cooler 5 and the work rolls of the hot rolling stand 3. The blank cooler 5, only shown schematically, sprays the hot strip 4 with cooling roller emulsion and ensures that the hot strip is cooled more quickly 4. The work rolls of the hot rolling stand 3 are charged with emulsion and cool the hot strip 4 further down. After the last rolling pass, the hot strip 4 at the outlet of the sinker cooler 5 'in the present exemplary embodiment has a temperature of only 95 ° C. and will then be wound up on the take-up reel 6.

Due to the fact that the hot strip 4 has a temperature of maximum 130 ° C or maximum 100 ° C directly at the outlet of the last hot rolling pass or optionally in the last two hot rolling passes using the blank cooler 5 and the work rolls of the hot rolling stand 3 to a temperature below Is brought 130 ° C or below 100 ° C, the hot strip 4 has a frozen crystal structure, since no additional energy in the form of heat is available for subsequent precipitation processes. The hot strip with a thickness of 3 to 12 mm, preferably 3.5 to 8 mm, is wound up on the take-up reel 6. As already stated, the winding temperature in the present exemplary embodiment is less than 95 ° C.

In the method according to the invention, no or only a few coarse Mg ₂ Si precipitates can now form in the wound hot strip 4. The hot strip 4 has a very favorable crystal state for further processing and can be unwound from the uncoiler 7, for example fed to a cold rolling stand 9 and rewound on a reel 8, Fig. 1c ).

The resulting cold rolled strip 11 is wound up. It is then subjected to solution annealing and quenching 10, Fig. 1d ). For this purpose, it is unwound again from the coil 12, solution-annealed in a furnace 10 and, after being quenched, wound up again into a coil 13. After cold aging at room temperature, the aluminum strip can then be delivered in state T4 with maximum formability. Alternatively (not shown), the aluminum strip 11 can be separated into individual sheets, which are present in state T4 after cold aging.

In the case of larger aluminum strip thicknesses, for example in chassis applications or components such as brake anchor plates, it is also possible, as an alternative, to perform a piece annealing and then quench the sheets.

In state T6, the aluminum strip or sheet is brought through a hot aging process at 100 ° C to 220 ° C in order to achieve maximum values for the proof stress. For example, hot aging can be carried out at 205 ° C / 30 min.

The aluminum strips produced according to the illustrated embodiment have a thickness of 0.5 to 4.5 mm, for example, after cold rolling. Strip thicknesses of 0.5 to 2 mm are usually used for car body applications and strip thicknesses of 2.0 mm to 4.5 mm for chassis parts in motor vehicle construction. In both areas of application, the improved elongation values in the manufacture of the components are of decisive advantage, since mostly strong sheet metal forming is carried out and high strengths are still required in the operating state (T6) of the end product.

Table 1 shows the alloy compositions of aluminum alloys from which aluminum strips were produced conventionally or according to the invention. In addition to the contents of alloy components shown, the aluminum strips contain aluminum and impurities as a residual proportion, individually a maximum of 0.05% by weight and a total of a maximum of 0.15% by weight. Table 1 rehearse Si wt% Fe% by weight Cu% by weight Mn% by weight Mg wt% Cr wt% Zn% by weight Ti wt% 409 1.29 0.17 0.001 0.057 0.29 <0.0005 <0.001 0.02 410 1.30 0.17 0.001 0.056 0.29 <0.0005 <0.001 0.0172 491-1 1.39 0.18 0.002 0.062 0.30 0.0006 0.01 0.0158 491-11 1.40 0.18 0.002 0.063 0.31 0.0006 0.0104 0.0147

The strips 409 and 410 were produced using a method according to the invention, in which the hot strip was cooled and wound up from approximately 400 ° C. to 95 ° C. within the last two hot rolling passes using a blank cooler and the hot rolls themselves. Table 2 shows the measured values of these samples "Inv." featured. This was followed by cold rolling to a final thickness of 1.04 mm.

Samples 491-1 and 491-11 were made with conventional hot rolling and cold rolling and with a "conv." featured.

The results of the mechanical properties shown in Table 2 clearly show the difference in the achievable elongation values A ₈₀ . Table 2 rehearse T4 T6 205 ° C / 30 min. thickness Rp0.2 R _m A ₈₀ Rp0.2 R _m A ₈₀ Δ Rp0.2 (mm) (MPa) (MPa) (%) (MPa) (MPa) (%) (MPa) 409 Inv. 1.04 100 220 31.3 187 251 16.2 87 410 Inv. 1.04 98 217 30.3 195 256 15.5 97 491-1 Mixed lot 1.04 92 202 27.8 180 235 14.7 88 491-11 Mixed lot 1.04 88 196 27.4 179 232 14.3 91

In order to achieve the T4 state, the samples were subjected to solution annealing with subsequent quenching and subsequent cold aging at room temperature. The T6 state was achieved by hot aging at 205 ° C for 30 minutes.

It was shown that the advantageous structure, which was set in samples 409 and 410 using the method according to the invention, made it possible to increase the elongation A ₈₀ with increased yield strength Rp0.2 and strength Rm. This structure leads to the particularly advantageous combination of high elongation at break A ₈₀ of at least 30% or at least 30% at very high values for the yield strength Rp0.2 of 80 to 140 MPa. In state T6, the yield strength can rise to over 185 MPa, with the elongation A ₈₀ remaining at more than 15%. The curability with a ΔRp0.2 of 87 or 97 MPa shows that, despite the increased elongation values of more than 15%, the exemplary embodiments according to the invention achieve a very good increase in the yield strength in the age-hardened state T6 when aged at 205 ° C./30 minutes .

The elongation at break values A ₈₀ , the yield strength values Rp0.2 and the tensile strength values Rm in the following tables were measured according to DIN EN.

$$\mathrm{1}\mathrm{.0}\%\le \mathrm{Si}\le \mathrm{1}\mathrm{,5}\%,$$

$$\mathrm{Fe}\le \mathrm{0,5}\%,$$

$$\mathrm{Cu}\le \mathrm{0,2}\%,$$

$$\mathrm{Mn}\le \mathrm{0,2}\%,$$

$$\mathrm{Cr}\le \mathrm{0,1}\%,$$

$$\mathrm{Zn}\le \mathrm{0,1}\%,$$

$$\mathrm{Ti}\le \mathrm{0,1}\%$$

und Rest Al sowie unvermeidbare Verunreinigungen maximal in Summe 0,15 %, einzeln maximal 0,05 %.The measured values could be verified in the state T4 by measurements on further tapes. The aluminum alloy of samples A and B had the following composition: $$\mathrm{0}\mathrm{.25}\%\le \mathrm{Mg}\le 0.6\%,$$

$$\mathrm{1}\mathrm{.0}\%\le \mathrm{Si}\le \mathrm{1}\mathrm{,\; 5th}\%,$$

$$\mathrm{Fe}\le 0.5\%,$$

$$\mathrm{Cu}\le 0.2\%,$$

$$\mathrm{Mn}\le 0.2\%,$$

$$\mathrm{Cr}\le 0.1\%,$$

$$\mathrm{Zn}\le 0.1\%,$$

$$\mathrm{Ti}\le 0.1\%$$

and the remainder Al as well as unavoidable impurities in total 0.15% maximum, individually maximum 0.05%.

Samples A and B were wound up using the method according to the invention by quenching the hot strip within the last two hot rolling passes to 95 ° C. and then cold rolled to a final thickness of 1.0 mm and 3.0 mm, respectively. In order to reach state T4, samples A and B were solution-annealed and cold-aged after quenching.

The following measured values could be determined on both samples: Table 3 rehearse T4 thickness Rp0.2 R _m A ₈₀ (mm) (MPa) (MPa) (%) A 1.0 107 221 31.1 B 3.0 108 212 32.0

The once again increased elongation values A ₈₀ show the outstanding suitability of these aluminum strips for the production of components in which very high degrees of deformation during production in state T4 must be combined with maximum tensile strengths Rm and yield strengths Rp0.2 in state T6.

Claims (10)

1. A method for producing a strip made of an AlMgSi alloy, in which a rolling ingot is cast of an AlMgSi alloy, the rolling ingot is subjected to homogenization and the rolling ingot, which was brought to the hot-rolling temperature, is hot-rolled and then optionally cold-rolled to its final thickness,
   characterized in that
   the hot strip has a temperature of at most 130°C, preferably a temperature of at most 100°C, immediately after it exits the last hot rolling pass, and in that the hot strip is coiled at this temperature or a lower temperature, where the hot strip is quenched to the exiting temperature by utilizing at least one plate cooler and by the hot rolling passes themselves that are acted upon by an emulsion.
2. The method according to claim 1,
   characterized in that
   the hot-rolling temperature of the hot strip lies at least at 230°C, preferably above 400°C, prior to the cooling process during the hot-rolling operation, particularly prior to the next-to-last hot rolling pass.
3. The method according to claim 1 or 2, characterized in that
   the thickness of the finished hot strip lies between 3 mm and 12 mm, preferably between 3.5 mm and 8 mm.
4. The method according to one of claims 1 to 3,
   characterized in that
   the aluminium alloy consists of the alloy type AA6xxx, preferably AA6014, AA6016, AA6060, AA6111 or AA6181.
5. An aluminium strip that consists of an AlMgSi alloy and is produced, in particular, by means of a method according to one of claims 1 to 4,
   characterized in that
   the aluminium strip has in the state T4 a breaking elongation A₈₀ of at least 30% at a proof stress Rp0,2 between 80 and 140 MPa.
6. The aluminium strip according to claim 5,
   characterized in that
   the solution heat-treated and quenched aluminium strip has in the state T6 after artificial aging at 205°C / 30 minutes a proof stress Rp0,2 in excess of 185 MPa.
7. The aluminium strip according to claim 5 or 6,
   characterized in that
   the solution heat-treated and quenched aluminium strip has in the state T6 after artificial aging at 205°C / 30 minutes a differential proof stress ΔRp0,2 between the states T6 and T4 of at least 80 MPa.
8. The aluminium strip according to one of claims 5 to 7,
   characterized in that
   the aluminium strip has a thickness between 0.5 and 12 mm.
9. The aluminium strip according to one of claims 5 to 8,
   characterized in that
   the aluminium alloy consists of the alloy type AA6xxx, preferably AA6014, AA6016, AA6060, AA6111 or AA6181.
10. The utilization of a metal sheet produced of an aluminium strip according to one of claims 5 to 9 as a component, chassis or structural member or metal sheet in the construction of motor vehicles, aircraft or rail vehicles, particularly in the form of a component, chassis member, exterior or interior metal sheet in the construction of motor vehicles, preferably a car body element.

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