Aluminium product with high recycling content for electrical conductors and method for the production thereof

Abstract

The invention relates to an aluminium alloy strip or sheet for electrical conductors produced by means of a continuous casting method, to a method for the production thereof, and to the use of the aluminium alloy strip as an electrical component or the production thereof. The problem addressed by the invention of providing an aluminium alloy strip which achieves high electrical conductivities and high yield strength values Rp0.2, allows a low C02 footprint in the production thereof and has a higher temperature resistance, is solved by an aluminium alloy strip or sheet produced by a continuous casting process, which consists of an aluminium alloy which contains the alloy elements Si, Fe, Cu, Mn and Mg and optionally Cr, Zn, Ti, V and Zr, and unavoidable impurities individually up to a maximum of 0.05 wt.%, in total up to a maximum of 0.15 wt.% and 97.0 wt.% ≤ Al ≤ 99.5 wt.%, wherein the aluminium alloy strip has an electrical conductivity of at least 27 MS / m and a yield strength Rp0.2 of at least 100 MPa, preferably at least 120 MPa.

Description

[0001] 7A / 7A 241192W0

[0002] February 6, 2026

[0003] Aluminium product with a high recycled content for electrical conductors and manufacturing processes

[0004] The invention relates to an aluminum alloy strip or sheet for electrical conductors manufactured using a continuous casting process, a method for its manufacture, and the use of the aluminum alloy strip as an electrical component or its manufacture.

[0005] Electrically conductive aluminum components are generally manufactured from alloys of the AAlxxx or AA6xxx series. AAlxxx alloys achieve the highest electrical conductivities because these materials allow only minimal impurities and alloying element concentrations. However, this severely limits the achievable strength, creep resistance, and the incorporation of recycled metal. Low-alloy AA6xxx alloys with low impurity concentrations enable higher strengths through precipitation hardening. However, here too, the potential for incorporating recycled material is limited by the severely restricted impurity concentrations. AA6xxx alloys also achieve their strength through precipitation hardening. They undergo solution annealing, typically followed by rapid cooling or quenching and subsequent warm aging.Warm aging temperatures typically range between 140 °C and 220 °C. Therefore, over long periods of elevated operating temperatures can lead to softening processes due to over-aging.

[0006] From European patent application EP 2527479 Al, aluminium strips are known which were produced from a rolling ingot by hot rolling and cold rolling and which, in addition to a high electrical conductivity of more than 30 MS / m, simultaneously have a high yield strength R PThe results show values ​​of 0.2 MPa exceeding 140 MPa in the re-annealed condition. However, these results could only be achieved through a close selection of the aluminum alloy with nearly identical Si, Fe, and Mg contents. This makes it economically impossible to meet the requirements for the lowest possible carbon footprint of the aluminum strips, as the compositions of recycled alloys vary too greatly. Furthermore, the known aluminum strips and sheets exhibit weaknesses in temperature resistance, meaning that softening processes can occur in these aluminum strips and sheets at elevated operating temperatures.

[0007] The object of the invention is therefore, starting from this prior art, to provide an aluminum alloy strip that, on the one hand, has high electrical conductivities and, on the other hand, high yield strengths R. P0.2 achieved, enables a low CCh footprint in its production and has higher temperature resistance.

[0008] According to the teaching of the present invention, this problem is solved by an aluminum alloy strip or sheet produced by a continuous casting process and consisting of an aluminum alloy comprising the alloying elements Si, Fe, Cu, Mn and Mg, as well as optionally Cr, Zn, Ti, V and Zr, and unavoidable impurities individually up to a maximum of 0.05 wt.%, in total up to a maximum of 0.15 wt.% and 97.0 wt.% < Al < 99.5 wt.%, wherein the aluminum alloy strip has an electrical conductivity of at least TI MS / m and a yield strength R P 0.2 has a strength of at least 100 MPa, preferably at least 120 MPa.

[0009] Surprisingly, it has been shown that an aluminum alloy strip produced using a continuous casting process exhibits high electrical conductivities of at least TI MS / m paired with high yield strength values ​​R. P A compressive strength of at least 100 MPa, preferably at least 120 MPa, can be achieved without limiting the aluminum alloy composition to nearly identical contents of the alloying elements Si, Mg, and Mn. This allows

[0010] ZI / ZI 241192WO February 6, 2026: The proportion of primary aluminum used to produce the aluminum alloy strip can be reduced, resulting in a lower carbon footprint. Furthermore, temperature resistance is significantly increased, so that virtually no softening is observed at operating temperatures around 200 °C. These properties are due to the microstructure of the aluminum strips produced by continuous casting compared to the microstructure of aluminum strips produced by casting a rolling ingot and hot and cold rolling.

[0011] The stated values ​​for the yield strength R P 0.2, tensile strength R m The elongation values ​​are in accordance with DIN EN ISO 6892-1. The electrical conductivity refers to values ​​in accordance with DIN EN 2004-1.

[0012] According to a first embodiment, the aluminium alloy strip or sheet exhibits a strength ratio of — after a temperature load of 200°C for 72 h, preferably for 168 h, more preferably for 720 h. R p°- 2 - T - belastet — von at least RpO,2_after_production

[0013] 0.8, preferably at least 0.85, further preferably at least 0.9, so that even with high heat input up to 200 °C in the application of the highly conductive, solid aluminum alloy strip, only very slight softening occurs. The yield strength R is used here as Rpo,2_T_beastet. P 0.2 is designated according to the temperature load and with R p 0.2_after_production the yield strength R P 0.2 immediately after the production of the aluminium alloy strip, for example after a corresponding annealing process.

[0014] Another embodiment of the aluminum alloy strip or sheet exhibits a strength ratio of — after a temperature load of 250°C for 72 h, preferably for 168 h, more preferably for 720 h. R p°- 2 - T - belastet — at least 0.8,

[0015] RpO,2 after production preferably at least 0.85, more preferably at least 0.9, thus providing further improved strength after temperature exposure up to 250 °C. This high temperature resistance opens up new possibilities for the aluminum alloy strip.

[0016] ZI / ZI 241192WO February 6, 2026 Application possibilities that were previously not feasible with an aluminum alloy strip due to expected softening.

[0017] The aluminium alloy strip according to the present invention preferably comprises an aluminium alloy with the following alloying elements in wt.%:

[0018] 0.12% <Si <0.7%, preferably 0.15% <Si <0.55%,

[0019] still preferred 0.20% < Si < 0.5%.

[0020] 0.2% < Fe < 0.7%, preferably 0.25% < Fe < 0.55%.

[0021] still preferred 0.3% < Fe < 0.5%.

[0022] 0.001% <Cu <0.25%, preferably 0.01% <Cu <0.2%,

[0023] still preferred 0.025% < Cu < 0.16%.

[0024] 0.25% < Mn < 1.02%, preferably 0.3% < Mn < 0.9%.

[0025] still preferred 0.35% < Mn < 0.7%.

[0026] 0.01% < Mg < 0.7%, preferably 0.1% < Mg < 0.6%.

[0027] further preferred 0.2 < Mg < 0.5 %,

[0028] Cr < 0.2%, preferably 0.0005% < Cr < 0.15%

[0029] further preferred 0.001% < Cr < 0.12%.

[0030] Zn < 0.5%, preferably 0.0001% < Zn < 0.25%.

[0031] still preferred 0.001% < Zn < 0.2%.

[0032] Ti <0.15%, preferably 0.0001% <Ti <0.1%,

[0033] further preferred 0.001% < Ti < 0.08%.

[0034] V < 0.05%, preferably V < 0.03%, further preferably V < 0.01%.

[0035] Zr < 0.05%, preferably Zr < 0.03%, further preferably Zr < 0.01%, unavoidable impurities, individually a maximum of 0.05%, in total a maximum of 0.15%, and remainder Al, wherein the residual content of Al is preferably 97.0% < Al < 99.5%, preferably 97.5% < Al < 99.25%, and further preferably 98.0% < Al < 98.8%.

[0036] As will be shown below, an aluminum alloy strip can be produced using the aluminum alloy with the specifications given above, which allows for a reduction in the use of primary aluminum while simultaneously providing a

[0037] ZI / ZI 241192WO 6 February 2026 high yield strength R P 0.2 and a very high electrical conductivity of at least 27 MS / m with particularly high temperature resistance.

[0038] The alloy composition of the embodiment of the aluminum alloy strip is described below. The silicon content of the aluminum alloy is preferably in the range of 0.12 wt.% < Si < 0.7 wt.%, thus allowing for high recycling rates. More preferably, the silicon content can be 0.15 wt.% < Si < 0.55 wt.%, and more preferably 0.20 wt.% < Si < 0.5 wt.%. In combination with iron and manganese contents, preferably in the specified amounts, the silicon content leads in particular to relatively uniformly distributed, compact particles of the quaternary α-Al(e,Mn)Si phase. These precipitated particles increase both the strength of the aluminum alloy and its electrical and thermal conductivity, as they remove iron and manganese from the solid solution.

[0039] Silicon contents of less than 0.12 wt.% lead to reduced precipitation of α-Al(Te,Mn)Si phases, which can impair electrical and thermal conductivity due to dissolved manganese. Excessively high silicon contents (> 0.7%) can lead to coarsening or an excessive number of coarse α-Al(Te,Mn)Si phases, which can impair formability, for example, under bending stress. A silicon content of 0.15 wt.% < Si < 0.55 wt.%, preferably 0.20 wt.% < Si < 0.5 wt.%, in combination with the other alloying elements iron and manganese, minimizes the solution content of these elements and thus optimizes electrical conductivity when processed using suitable thermomechanical methods.

[0040] The iron content of the aluminum alloy is preferably 0.2 wt.% < Fe < 0.7 wt.%. This content allows for a high scrap input in the production of the aluminum alloy strip and increases scrap availability, i.e., the selection of which scrap is suitable for use as a recycled alloy in the production of the aluminum alloy strip. In a preferred embodiment of the aluminum alloy strip, the iron content is 0.25 wt.% < Fe < 0.55 wt.%, preferably 0.3 wt.% < Fe < 0.5 wt.%. Iron, as already mentioned above,

[0041] ZI / ZI 241192WO 6 February 2026, in combination with silicon and manganese, preferably in amounts as specified, for the precipitation of particles of the quaternary α-Al(Te,Mn)Si phase, which reduce the solution content of the elements mentioned and optimize the electrical conductivity during suitable heat treatments.

[0042] In addition, the intermetallic phases influence recovery and recrystallization processes and improve the thermal stability of the mechanical properties.

[0043] The copper content of the aluminum alloy is preferably 0.001 wt.% < Cu < 0.25 wt.%. This copper content allows the use of common AA3xxx scrap for the production of the aluminum alloy strip, thus facilitating the achievement of high recycling rates. In one embodiment of the aluminum alloy strip, the copper content is 0.01 wt.% < Cu < 0.2 wt.%, preferably 0.025 wt.% < Cu < 0.16 wt.%. In these ranges, copper contributes to increased strength without significantly impairing electrical conductivity or corrosion resistance.

[0044] The manganese content of the aluminum alloy is preferably 0.25 wt.% < Mn < 1.02 wt.%. In a preferred embodiment, the manganese content of the aluminum alloy is 0.3 wt.% < Mn < 0.9 wt.%, further preferably

[0045] 0.35 wt% < Mn < 0.7 wt%. As already explained above, the manganese content, in combination with silicon and iron, preferably in the specified amounts, leads to the precipitation of particles of the quaternary α-Al(Fe,Mn)Si phase and the A16(Mn,Fe) phase. These intermetallic phases, as well as dissolved manganese, influence recovery and recrystallization processes and thus contribute to improved thermal stability of the mechanical properties of the aluminum alloy strip. By combining the alloying elements Si, Fe, and Mn in conjunction with the continuous casting process and suitable thermomechanical process control, the solution state is adjusted to achieve optimized electrical conductivity with high strength and thermal stability.

[0046] ZI / ZI 241192WO February 6, 2026 The magnesium content of the aluminum alloy is preferably 0.01 wt.% < Mg < 0.7 wt.%. In further preferred embodiments of the aluminum alloy strip, the magnesium content is

[0047] 0.1 wt.% < Mg < 0.6 wt.%, preferably at 0.2 wt.% < Mg < 0.5 wt.%.

[0048] By allowing a magnesium content of up to 0.7 wt.%, the tolerance of the aluminum alloy to magnesium-containing aluminum alloy scrap, such as used beverage can (UBC) scrap, is achieved, thus facilitating the realization of high recycling rates in the aluminum alloy during production. Furthermore, magnesium increases the strength of the aluminum alloy strips through solid solution strengthening without significantly affecting electrical conductivity. Preferred magnesium content ranges are 0.1 wt.% < Mg < 0.6 wt.%, and more preferably 0.2 wt.% < Mg < 0.5 wt.%, providing the best compromise between high electrical conductivity and strength.

[0049] The chromium content of the aluminum alloy is preferably

[0050] Chromium < 0.2 wt.%, preferably 0.0005 wt.% < Cr < 0.15 wt.%, and further preferably 0.001 wt.% < Cr < 0.12 wt.%. Chromium forms fine dispersoids in aluminum alloys, which help control the grain structure and improve thermal stability. Excessively high chromium contents above 0.2 wt.% can lead to the formation of coarse intermetallic phases. Furthermore, chromium significantly impairs the electrical conductivity of aluminum alloys. The preferred embodiments offer an optimal compromise between conductivity requirements and thermal stability. At the same time, they also facilitate the recycling of chromium-containing aluminum alloys.

[0051] The zinc content of the aluminum alloy is preferably < 0.5 wt.%. In one embodiment of the aluminum alloy strip, the zinc content is 0.0001 wt.% < Zn < 0.25 wt.%, and particularly preferably 0.001 wt.% < Zn < 0.2 wt.%. Zinc is a common component in aluminum alloy scrap. Therefore,

[0052] ZI / ZI 241192WO February 6, 2026: Allowing a zinc content of up to 0.5 wt.% results in increased tolerance of the aluminum alloy for zinc-containing aluminum alloy scrap, which facilitates the realization of high recycling rates in the production of aluminum alloy strips. The zinc content only slightly affects electrical conductivity; however, excessively high zinc contents can impair corrosion resistance. Preferred zinc contents of 0.0001 wt.% < Zn < 0.25 wt.%, and more preferably 0.001 wt.% < Zn < 0.2 wt.%, represent a compromise between recyclability and corrosion resistance.

[0053] The titanium content of the aluminum alloy is preferably < 0.15 wt.%. In a further embodiment of the aluminum alloy strip, the titanium content is preferably < 0.0001 wt.% < Ti < 0.1 wt.%, and particularly preferably < 0.001 wt.% < Ti < 0.08 wt.%. Titanium-boron compounds are primarily used as grain refiners in aluminum alloy casting. As a result, titanium is a common accompanying element in aluminum alloy scrap. By allowing a titanium content of up to 0.15 wt.%, an increased tolerance of the aluminum alloy for titanium-containing aluminum alloy scrap is achieved, which facilitates the realization of high recycling rates. However, titanium reduces electrical conductivity comparatively significantly, so the titanium content is limited to < 0.15 wt.%.

[0054] The vanadium content of the aluminum alloy is preferably V < 0.05 wt.%. In a further embodiment, the vanadium content is preferably

[0055] V < 0.03 wt.%, particularly preferably V < 0.01 wt.%. Vanadium has a grain-refining effect during the solidification of aluminum. Furthermore, vanadium increases the recrystallization temperature and can thus contribute to increased thermal stability. Since vanadium significantly impairs electrical conductivity, the vanadium content is preferably limited to V < 0.03 wt.%, and more preferably to 0.01 wt.%. The vanadium content of the aluminum alloy strip can be reduced during the casting process by boron treatment.

[0056] ZI / ZI 241192WO February 6, 2026 Zircon forms intermetallic phases that hinder recovery and recrystallization processes. As a result, zirconium increases the thermal stability of aluminum alloys. However, zirconium also significantly impairs the electrical conductivity of aluminum alloys. Therefore, the zirconium content of the aluminum alloy is preferably Zr < 0.05 wt.%. In a further embodiment of the aluminum alloy strip, the Zr content is preferably Zr < 0.03 wt.%, particularly preferably Zr < 0.01 wt.%, so that the electrical conductivity of the aluminum alloy is further increased.

[0057] The aluminum content of the aluminum alloy is preferably 97.0 wt.% < Al < 99.5 wt.%, more preferably 97.5 wt.% < Al < 99.25 wt.%, and further preferably 98.0 wt.% < Al < 98.8 wt.%. This aluminum content allows for a high proportion of other alloying elements and impurities, with the high proportion of impurities improving the use of recycled alloys. With suitable process parameters during the continuous casting of the aluminum alloy strip and optimized thermomechanical process control, high electrical conductivities combined with high thermal stability can still be achieved.

[0058] According to one embodiment, the aluminum alloy strip or sheet has a Si / Fe ratio of 0.45 < Si / Fe < 1.5, preferably 0.75 < Si / Fe < 1.25. As explained above, silicon and iron, in combination with the manganese content, form intermetallic phases. At the aforementioned Si / Fe ratio, a particularly large number of these intermetallic phases are formed during casting and annealing as part of the thermomechanical process. This reduces the dissolved manganese content and thus further optimizes the electrical conductivity of the aluminum alloy strip. With the preferred Si / Fe ratio, the highest strengths combined with an electrical conductivity of more than 31 MS / m can therefore be achieved.

[0059] ZI / ZI 241192WO February 6, 2026. If the aluminum alloy strip or sheet has an electrical conductivity of at least 28.0 MS / m, preferably at least 30.0 MS / m, and more preferably at least 31.0 MS / m, busbars with very low electrical resistance can be produced from the aluminum alloy strip or sheet. This allows, for example, a reduction in the cross-sections of the busbars, which has a positive effect on the installation space and material usage.

[0060] In a further embodiment, the aluminum alloy strip or sheet can, in addition to conducting current, also perform functions of a structural component. Preferably, the aluminum alloy strip or sheet therefore has a yield strength R PThe tensile strength of the aluminum alloy strip must be at least 140 MPa, particularly preferably at least 160 MPa, preferably measured transversely to the rolling direction. Furthermore, the strength of the aluminum alloy strip significantly influences the applicability of force-fit connections, such as bolted busbar connections. High surface pressures are required for low contact resistances, which are only achievable with sufficiently strong aluminum materials. Therefore, this embodiment of the aluminum alloy strip can be used at very high surface pressures.

[0061] If, according to a further embodiment, the aluminium alloy strip or sheet has an elongation at break Aso of at least 4%, preferably at least 6%, or at least 8%, preferably measured transversely to the rolling direction, the aluminium alloy strip or sheet can be formed sufficiently well for the application.

[0062] Recycling aluminum scrap is significantly less energy-intensive compared to primary aluminum production. Therefore, the carbon footprint of producing the aluminum alloy strip can be further reduced by...

[0063] ZI / ZI 241192WO 6 February 2026 Aluminium alloy strip or sheet having a primary aluminium content of a maximum of 80%, preferably a maximum of 70% or preferably a maximum of 60%.

[0064] A further embodiment of the aluminum alloy strip or sheet is particularly advantageous in that it has a thickness of 0.5 mm to 10 mm, preferably 0.75 mm to 9 mm, or more preferably 1 mm to 8 mm. These thicknesses are especially suitable for electrical components such as busbars, which must conduct particularly high electrical currents. Depending on the thickness of the electrical component or the corresponding final thickness of the aluminum alloy strip, the strip thickness must be adjusted via the continuous casting process used and the process parameters employed so that a sufficiently high degree of cold rolling can be achieved to attain the required strength. Thus, strips produced using a twin-roll caster can typically have thicknesses between 3 mm and 12 mm, while twin-belt casters enable strip thicknesses of up to 50 mm.

[0065] The aluminum alloy strip or sheet can be readily adapted to the specific application by having a cold-worked and annealed condition H2X, H3X, or H4X, preferably one of the cold-worked and annealed conditions H22, H24, H26, H28, H32, H34, H36, H38, or H42, H44, H46, H48. These conditions allow, in particular, the strength of the aluminum alloy strip to be adjusted while maintaining high electrical conductivity.

[0066] As previously stated, the aluminum alloy strip or sheet is preferably used as an electrical component, preferably in the form of a busbar, or for the manufacture of a current-carrying component, preferably a busbar. A busbar typically serves to transport high currents and, due to its large conductor cross-sections and high electrical conductivity (G), can transport these currents with minimal heating and losses. Even with continuous use of the components at very high temperatures, the...

[0067] ZI / ZI 241192WO February 6, 2026 Strength of the busbar made from the aluminum alloy strip according to the invention is almost non-existent.

[0068] According to the present invention, the problem identified is also solved by a method for producing an aluminum alloy strip according to the invention in that

[0069] an aluminum melt is cast into an aluminum alloy strip through a continuous casting process, preferably by casting rollers,

[0070] the aluminum alloy strip is rolled to its final thickness by cold rolling and

[0071] is subjected to a state annealing.

[0072] Continuous casting of aluminum strips is primarily carried out using roll casting. Twin-roll casters or twin-belt casters can be employed for this purpose. Other applicable casting methods include wheel-belt casters, rotary casters, and block casters. In continuous roll casting, the molten aluminum is cooled very rapidly between the casting rolls or casting chains arranged on both sides, for example, when using a twin-roll or twin-belt caster. The continuous casting method can be selected depending on the final thickness of the aluminum alloy strip and the required degree of cold rolling. For example, strips produced using twin-roll casters typically have thicknesses between 3 mm and 12 mm, while twin-belt casters allow for thicknesses of up to 50 mm. The cooling rates depend on the thickness of the cast strip. The thinner the cast aluminum alloy strip, the higher the cooling rate.The higher the cooling rate during casting, the higher the solution content of alloying elements and trace elements in the cast aluminum alloy strip, as the formation of intermetallic phases is kinetically suppressed. This results in a strong supersaturation of the alloy in the aforementioned continuous casting processes.

[0073] ZI / ZI 241192WO 6 February 2026Aluminium alloy strip on the alloying elements (Si, Fe, Mn, Cr, V and Zr] achieved, which is retained during cold rolling.

[0074] In contrast, the supersaturation in conventionally DC-cast rolling ingots is already limited within the ingot itself due to the significantly slower cooling rate during casting. Further processing, including preheating and hot rolling, leads to additional precipitation of intermetallic particles in the DC process, resulting in a generally much lower solution content in cold-rolled aluminum alloy strip produced by the DC process compared to continuously cast and cold-rolled aluminum alloy strip. The solution state, as well as the volume fraction and size of the intermetallic phases, significantly influences recovery and recrystallization processes.

[0075] In the case of continuously cast aluminum alloy strips, the strength and electrical conductivity can be particularly advantageously adjusted through annealing. A high degree of supersaturation, such as that achieved through the high cooling rate in continuous casting processes, hinders recovery and recrystallization processes, thus accelerating the softening of the aluminum alloy strip to higher temperatures. Consequently, sufficiently high strength can be achieved despite a comparatively high annealing temperature. Simultaneously, at a sufficiently high annealing temperature, the supersaturation is reduced by the formation of intermetallic phases due to the temperature-dependent solubilities of the individual alloying elements and their temperature-dependent diffusion.As a result, the electrical conductivity of the aluminum alloy strip increases, since elements dissolved in the aluminum solid solution impair electrical conductivity more than when bound in the form of intermetallic phases. A suitable annealing process thus simultaneously optimizes the solution state (i.e., electrical conductivity), elongation at break, and strength, resulting in a...

[0076] ZI / ZI 241192WO 6 February 2026 a strong and highly conductive aluminium alloy strip can be produced, despite comparatively low purity.

[0077] According to another embodiment, the aluminum alloy strip can be wound into a coil or cut into sheets before or after the annealing process. This allows for the provision of the usual delivery forms and efficient annealing, for example, in the coil or on the sheet.

[0078] According to a further embodiment of the process, cold rolling is carried out without intermediate annealing, wherein the degree of cold rolling before the final annealing is between 12% and 90%, preferably between 20% and 80%, and more preferably between 30% and 70%. A sufficiently high degree of cold rolling is required to meet the strength requirements of the aluminum alloy strip through work hardening. Furthermore, annealing is necessary to optimize the solution state and thus the electrical conductivity. Since the work hardening is reduced during the annealing process and the aluminum alloy strip therefore loses strength, a degree of cold rolling in the aforementioned range is required to meet the strength requirements even after annealing. However, a degree of cold rolling above 90% lowers the recrystallization temperature too much.Consequently, the maximum temperature of the annealing process is reduced for cold-rolled steel, making it impossible to optimize electrical conductivity by high annealing temperatures due to a significant loss of strength through recrystallization. Limiting the degree of rolling, preferably to a maximum of 80% or more preferably to a maximum of 70%, allows for a large process window with respect to the annealing temperature, with the aim of achieving high electrical conductivity G combined with high strength, particularly a high yield strength R. P to achieve 0.2.

[0079] The final annealing is preferably carried out at a peak metal temperature (PMTJ) of 310 °C < T < 400 °C, preferably 325 °C < T < 390 °C, more preferably 350 °C < T < 380 °C, wherein the holding time t is set to PMT <

[0080] ZI / ZI 241192WO February 6, 202624 h, preferably 1 min < t < 24 h, more preferably 5 min < t < 22 h or more preferably 0.5 h < t < 20 h, wherein coil annealing is preferably carried out. The temperatures mentioned below in connection with the state annealing always refer to the peak metal temperature (PMT) of the aluminum alloy strip. The state annealing serves to optimize the electrical conductivity and elongation at break while maintaining the required strength. By a state annealing at a peak metal temperature (PMT) T of 310 °C < T < 400 °C, preferably 325 °C < T < 390 °C, more preferably

[0081] At 350 °C < T < 380 °C with a holding time t at PMT < 24 h, preferably 1 min < t < 24 h, more preferably 5 min < t < 22 h or more preferably 0.5 h < t < 20 h, the aluminum alloy strip recovers, which increases the elongation at break and only slightly reduces the strength. Preferably, the temperature of the annealing process is selected such that complete recrystallization, which would produce a soft material state, is avoided. Due to the high supersaturation of the continuously cast and cold-rolled aluminum alloy strip, the temperatures T for the annealing process must be selected in the range of 310 °C < T < 400 °C, preferably 325 °C < T < 390 °C, more preferably 350 °C < T < 380 °C with a holding time t on PMT < 24 h, preferably 1 min < t < 24 h, more preferably 5 min < t < 22 h or more preferably 0.5 h < t < 20 h in order to achieve the strength and elongation requirements.Furthermore, at sufficiently high annealing temperatures, the supersaturation of the aluminum alloy strip is reduced due to the formation of intermetallic phases, the solution content is lowered, and thus the electrical conductivity is significantly increased. While further increasing the annealing temperature, for example above 400 °C, can optimize the electrical conductivity even further, there is then a risk of complete softening through recrystallization, meaning that the strength requirements can no longer be met. It has been found that the intended annealing process thermally stabilizes the microstructure and prevents further softening during operation at typical operating temperatures up to a maximum of 250 °C.

[0082] ZI / ZI 241192WO February 6, 2026. According to a further embodiment of the process, the cooling rate during the continuous casting process above 340°C is at least 75°C / s, preferably at least 100°C / s, and more preferably at least 125°C / s. At these cooling rates in the casting process, sufficient supersaturation of alloying and accompanying elements in the aluminum matrix is ​​achieved, which enables optimization of strength, elongation at break, electrical conductivity, and thermal resistance during cold rolling and subsequent annealing. The supersaturation of alloying and accompanying elements in the aluminum matrix increases with increasing cooling rate.

[0083] Finally, a primary aluminum content of up to 80%, preferably up to 70%, and most preferably up to 60% is preferably used to provide the molten aluminum. A decreasing proportion of primary aluminum significantly reduces the energy consumption for producing the aluminum alloy strip and, consequently, the CO2 emissions due to the increased recycling rate. As a result, the aluminum alloy strip has a lower CO2 footprint.

[0084] Due to the outstanding combination of high electrical conductivity, high strength through high yield strength values ​​R PWith a hardness of 0.2 and very low softening under heat stress at temperatures of 200 °C and 250 °C respectively, the aluminum alloy strip is used to manufacture an electrical component, preferably a busbar, preferably for use in heat-stressed environments. Other electrical components that can be manufactured from an aluminum alloy strip and are preferably used in heat-stressed environments include current-carrying elements of any shape.

[0085] The invention will now be explained in more detail using exemplary embodiments in conjunction with the drawing. The drawing shows in

[0086] ZI / ZI 241192WO 6 February 2026 Fig. 1 in a diagram the electrical conductivity of embodiments 1 to 16 made of alloy A as a function of the annealing temperature of the annealing process for two different final thicknesses and cold rolling degrees,

[0087] Fig. 2 shows the yield strength R in a diagram. P 0.2 the embodiments 1 to 16 made from alloy A as a function of the annealing temperature of the state annealing for two different final thicknesses and cold rolling degrees,

[0088] Fig. 3 shows in a diagram the electrical conductivity of embodiments 17 to 32 made of alloy B as a function of the annealing temperature of the annealing process for two different final thicknesses and cold rolling degrees.

[0089] Fig. 4 shows the yield strength R in a diagram. P 0.2 of embodiments 17 to 32 made of alloy B as a function of the annealing temperature of the state annealing for two different thicknesses and cold rolling degrees,

[0090] Fig. 5 shows the yield strength R in a diagram. P 0.2 of embodiments 41 to 58 depending on the duration of a thermal load for two different temperatures,

[0091] Fig. 6 shows in a diagram the strength ratio from the yield strength R. P 0.2 after temperature stress and yield strength R P 0.2 in the delivery state before the temperature load of embodiments 41 to 58 as a function of the duration of the thermal load for two different temperatures,

[0092] ZI / ZI 241192WO 6 February 2026 Fig. 7 in a diagram the electrical conductivity of embodiments 41 to 58 as a function of the duration of thermal stress for two different temperatures,

[0093] Fig. 8 shows a schematic representation of an embodiment of a manufacturing process for the aluminium alloy strip and

[0094] Fig. 9 Examples of uses of the aluminium alloy strip.

[0095] As exemplary embodiments, aluminum alloy strips were cast from a molten aluminum alloy using a twin-roll caster, cold-rolled to final thickness, and subjected to a final annealing. The aluminum alloy compositions are given in Table 1.

[0096] The respective aluminum alloy melts were cast at a temperature of 680 °C to 700 °C using a twin-roll caster with casting rollers with a diameter of 660 to 900 mm to form a strip of aluminum alloy, the thickness of which is given in Table 2. The casting speed of the aluminum alloy melt during the casting process was 1.2 to 1.7 m / min, with a cooling rate of at least 150 °C / s in the temperature range from the temperature of the aluminum melt to 340 °C. Examples 1 to 16 and 17 to 32 were each produced from a strip of aluminum alloy A or B, which was first cold-rolled to a thickness of 3.0 mm. Tensile specimens were taken from the strips at a final thickness of 3.0 mm and subjected to different annealing conditions. The tensile specimens were then subjected to laboratory-scale coil annealing simulations. The PMT of the annealing process shown in Table 2 was maintained for 3 h during laboratory annealing.The further manufacturing conditions and the mechanical properties of the different experiments of examples 1 to 8 (alloy A) and 17 to 24 (alloy B) are shown in Table 2.

[0097] ZI / ZI 241192WO February 6, 2026 Another portion of the two cast strips made of alloys A and B was cold-rolled to a final thickness of 1.5 mm. Tensile specimens taken from these were also subjected to different annealing processes on a laboratory scale. Here, too, a coil annealing simulation was performed with a holding time of 3 h on PMT according to Table 2. The mechanical properties of the different tests of Examples 9 to 16 (alloy A) and 25 to 32 (alloy B) are shown in Table 2. Figures 1-4 show the curves of the electrical conductivity G and the yield strength R. P 0.2 as a function of the PMT of the sample during the annealing process, graphically.

[0098] Figures 1 to 4 show the relationship between the temperature of the annealing process, here performed as a coil annealing simulation on tensile specimens with 3 h PMT, the electrical conductivity G and the yield strength R. P Figures 1 and 2 show the relationship for aluminum alloy A and Figures 3 and 4 show the relationship for aluminum alloy B. Of particular interest in both cases is the formation of a strength plateau between annealing temperatures of 300 °C and 400 °C, which, with increasing electrical conductivity G, enables a process window for the production of aluminum strips and sheets according to the invention.

[0099] Cast strips with the specified thicknesses and parameters listed in Table 2 were also produced from aluminum alloys C to J. The cold-rolled strips underwent coil annealing with a holding time of 3–5 hours at the specified annealing temperature. The primary aluminum content of alloys A to J ranges from 30% to 98%. Example D, for instance, has a very low primary aluminum content of 30%, with external scrap accounting for 62% and internal process scrap for 5%.

[0100] Surprisingly, it was found that the manufacturing process according to the invention achieved high electrical conductivities and strengths even at very high temperatures.

[0101] ZI / ZI 241192WO 6 February 2026 high external scrap content, i.e. very low primary aluminum content, can be realized.

[0102] The casting strips designated REF are comparison strips that either do not meet the required values ​​for electrical conductivity o or for yield strength R. P 0.2 was reached.

[0103] It was shown that, contrary to the previously known state of the art, due to the microstructure of the cast strips made of an aluminum alloy, which contains the alloying elements Si, Fe, Cu, Mn and Mg as well as optionally Cr, Zn, Ti, V and Zr, and unavoidable impurities individually up to a maximum of 0.05 wt.%, in total up to a maximum of 0.15 wt.% and 97.0 wt.% < Al < 99.5 wt.%, aluminum alloy strips with an electrical conductivity G of at least 27 MS / m and a yield strength R P 0.2 of at least 100 MPa, preferably at least 120 MPa, could be produced without, for example, having to keep the contents of the alloying elements Si, Fe, and Mg at identical levels.

[0104] As can be seen from the examples, the aluminum alloy strip preferably has an aluminum alloy with the following alloying elements in wt.%:

[0105] 0.12% <Si <0.7%, preferably 0.15% <Si <0.55%,

[0106] still preferred 0.20% < Si < 0.5%.

[0107] 0.2% < Fe < 0.7%, preferably 0.25% < Fe < 0.55%.

[0108] still preferred 0.3% < Fe < 0.5%.

[0109] 0.001% <Cu <0.25%, preferably 0.01% <Cu <0.2%,

[0110] still preferred 0.025% < Cu < 0.16%.

[0111] 0.25% < Mn < 1.02%, preferably 0.3% < Mn < 0.9%.

[0112] still preferred 0.35% < Mn < 0.7%.

[0113] 0.01% < Mg < 0.7%, preferably 0.1% < Mg < 0.6%.

[0114] further preferred 0.2 < Mg < 0.5 %,

[0115] Cr < 0.2%, preferably 0.0005% < Cr < 0.15%

[0116] ZI / ZI 241192WO 6 February 2026 further preferred 0.001% < Cr < 0.12%

[0117] Zn < 0.5%, preferably 0.0001% < Zn < 0.25%.

[0118] still preferred 0.001% < Zn < 0.2%.

[0119] Ti <0.15%, preferably 0.0001% <Ti <0.1%,

[0120] further preferred 0.001% < Ti < 0.08%.

[0121] V < 0.05%, preferably V < 0.03%, further preferably V < 0.01%.

[0122] Zr < 0.05%, preferably Zr < 0.03%, further preferably Zr < 0.01%, unavoidable impurities, individually a maximum of 0.05%, in total a maximum of 0.15%, and remainder Al, wherein the residual content of Al is preferably 97.0% < Al < 99.5%, preferably 97.5% < Al < 99.25%, and further preferably 98.0% < Al < 98.8%.

[0123] For the aluminum alloys A, B, C, D, E, F, G and 1, which lie within the alloy definition given above, strips with the desired combination of electrical conductivity G and yield strength R could be obtained.P 0.2 are produced. For alloy composition H, insufficient electrical conductivity was achieved under the production conditions used. This alloy composition has a high Mn content combined with low Si and Fe contents, resulting in reduced formation of the α-Al(Fe,Mn)Si phase and the A16(Mn,Fe) phase, and consequently, a high proportion of the alloy's Mn content remains in solution. This significantly impairs the electrical conductivity, preventing the required electrical conductivity from being achieved at the annealing temperature used. Aluminum alloy J has a very low Si content, which also hinders the formation of α-Al(Fe,Mn)Si phases. As a result, the electrical conductivity is excessively reduced under the manufacturing conditions due to the high solution content.

[0124] Particularly high values ​​for electrical conductivity G were achieved in embodiment 33 made of aluminum alloy C. Tensile specimens were then taken and subjected to different thermal loads. For this purpose, isothermal annealing at 200 °C and 250 °C was performed to simulate a

[0125] ZI / ZI 241192WO February 6, 2026. Temperature stress test performed for up to 720 hours. The determined values ​​for electrical conductivity G and yield strength R P 0.2 and the ratio of the yield strengths — R p°- 2 - T - belastet — sinc [ j n Table 3 and Figures 5 to 7 pO,2_after_production

[0126] depicted.

[0127] It was found that the aluminium alloy strip or sheet, after a temperature load of 200 °C or 250 °C for 72 h, preferably for 168 h, more preferably for 720 h, exhibited a strength ratio of — R p°- 2 - T- belastet — von at least pO2_after_production

[0128] has a value of 0.9.

[0129] The aluminum alloy strips made from aluminum alloys A to F have a Si to Fe ratio of 0.45 < Si / Fe < 1.5 preferably 0.75 < Si / Fe < 1.25 and exhibit the desired combination of properties even at lower annealing temperatures from 310 °C.

[0130] Aluminium alloy strips or sheets having an electrical conductivity G of at least 28 MS / m, preferably 30.0 MS / m, particularly preferably at least 31.0 MS / m, could be produced using aluminium alloys A, B, C, D, E and 1.

[0131] High-strength aluminum alloy strips or sheets with a yield strength R P 0.2 of at least 140 MPa, preferably at least 160 MPa, could also be produced with the aluminum alloys A, B, C, D, E, F and 1.

[0132] All aluminium alloy strips or sheets according to the invention have an elongation at break Aso of at least 4%, preferably at least 6%, or at least Aso > 8%.

[0133] Fig. 8 schematically shows an embodiment of a method for producing the aluminum alloy strip. The method consists of the following steps:

[0134] ZI / ZI 241192WO February 6, 2026 - Casting an aluminum melt by a continuous casting process, preferably by casting rolls, into an aluminum alloy strip according to step a, - Cold rolling of the aluminum alloy strip to final thickness according to step b and

[0135] - Subjecting the aluminium alloy strip to a state annealing according to step d.

[0136] Preferably, the cooling rate during continuous casting according to step a above 340 °C is at least 75 °C / s, preferably at least 100 °C / s, more preferably at least 125 °C / s, in order to create a supersaturated state of the alloy and impurity elements in the aluminium alloy strip.

[0137] Cold rolling according to step b can also be carried out with an intermediate annealing according to step z, followed by further cold rolling to the final thickness. Preferably, however, cold rolling according to step b is carried out without intermediate annealing, with the degree of cold rolling before the final annealing being between 12% and 90%, preferably between 20% and 80%, and more preferably between 30% and 70%. This keeps the recrystallization temperature within a temperature range above the intended PMT of the final annealing and preferably prevents recrystallization.

[0138] The annealing process according to step d is carried out to achieve the required conductivity values ​​G and the desired mechanical strength R. P To achieve 0.2, the final annealing process according to step c is preferably carried out at a peak metal temperature (PMT) T of 310 °C < T < 400 °C, preferably 325 °C < T < 390 °C, more preferably 350 °C < T < 380 °C, wherein the holding time t is PMT < 24 h, more preferably 1 min < t < 24 h.

[0139] The duration is 5 min < t < 22 h. With the aforementioned parameters of the annealing process, the advantageous properties of the cast aluminum alloy strips can be achieved.

[0140] ZI / ZI 241192WO February 6, 2026. According to a further embodiment, the aluminum alloy strip can be wound into a coil or cut into sheets before or after the annealing process, step c. In the coil, the annealing process can be carried out, for example, in known chamber furnaces used for coil annealing. This also applies in principle to sheets of the aluminum alloy strip. In principle, however, annealing in a continuous furnace is also conceivable.

[0141] Fig. 9 shows the use of the aluminum alloy strip as a current-carrying component, or the use of the aluminum alloy strip for the manufacture of the current-carrying component.

[0142] Figure 9 schematically depicts two current-carrying busbars 2a and 2b, which are electrically connected to each other by a connector 1. Both the busbars 2a and 2b, and the connector 1 (also made of aluminum alloy strip), require very good mechanical strength to ensure a sufficiently secure connection to the busbars 2a and 2b. At the same time, the aluminum alloy strip provides the highest possible electrical conductivity G, enabling the transmission of high currents with low electrical resistance.

[0143] ZI / ZI 241192WO February 6, 2026Table 1

[0144]

[0145] 5

[0146] ZI / ZI 241192WO 6 February 2026 Table 2 *TD: transverse to the rolling direction

[0147]

[0148] ZI / ZI 241192WO February 6, 2026

[0149]

[0150] ZI / ZI 241192WO February 6, 2026Table 3

[0151]

[0152] ZI / ZI 241192WO 6 February 2026

Claims

7A / 7A 241192W0 February 6, 2026 Patent claims 1. Aluminum alloy strip or sheet produced by a continuous casting process, consisting of an aluminum alloy containing the alloying elements Si, Fe, Cu, Mn and Mg, and optionally Cr, Zn, Ti, V and Zr, unavoidable impurities individually up to a maximum of 0.05 wt.%, in total up to a maximum of 0.15 wt.% and 97.0 wt.% < Al < 99.5 wt.%, wherein the aluminum alloy strip has an electrical conductivity G of at least 27 MS / m and a yield strength R P 0.2 has a strength of at least 100 MPa, preferably at least 120 MPa.

2. Aluminium alloy strip or sheet according to claim 1, characterized by the fact that The aluminium alloy strip or sheet, after a temperature load of 200°C for 72 h, preferably for 168 h, more preferably for 720 h, exhibits a strength ratio of — R p°- 2 - T -belastet — von at least 0.8, preferably at least pO2_after_production 0.85, preferably at least 0.

9.

3. Aluminium alloy strip or sheet according to one of claims 1 or 2, characterized in that The aluminium alloy strip or sheet exhibits a strength ratio of — after a temperature load of 250°C for 72 h, preferably for 168 h, more preferably for 720 h. R p°- 2 - T - belastet — at least 0.8, preferably at least 0.85, pO2_after_production preferably has at least 0.

9.

4. Aluminium alloy strip or sheet according to one of claims 1 to 3, characterized in that the aluminium alloy strip or sheet comprises an aluminium alloy with the following alloying elements in wt.%: 0.12% <Si <0.7%, preferably 0.15% <Si <0.55%, still preferred 0.20% < Si < 0.5%. 0.2% < Fe < 0.7%, preferably 0.25% < Fe < 0.55%. still preferred 0.3% < Fe < 0.5%. 0.001% <Cu <0.25%, preferably 0.01% <Cu <0.2%, still preferred 0.025% < Cu < 0.16%. 0.25% < Mn < 1.02%, preferably 0.3% < Mn < 0.9%. still preferred 0.35% < Mn < 0.7%. 0.01% < Mg < 0.7%, preferably 0.1% < Mg < 0.6%. further preferred 0.2 < Mg < 0.5 %, Cr < 0.2%, preferably 0.0005% < Cr < 0.15% further preferred 0.001% < Cr < 0.12%. Zn < 0.5%, preferably 0.0001% < Zn < 0.25%. still preferred 0.001% < Zn < 0.2%. Ti <0.15%, preferably 0.0001% <Ti <0.1%, further preferred 0.001% < Ti < 0.08%. V < 0.05%, preferably V < 0.03%, further preferably V < 0.01%. Zr < 0.05%, preferably Zr < 0.03%, further preferably Zr < 0.01%, unavoidable impurities, individually a maximum of 0.05%, in total a maximum of 0.15%, and remainder Al, wherein the residual content of Al is preferably 97.0% < Al < 99.5%, preferably 97.5% < Al < 99.25%, and further preferably 98.0% < Al < 98.8%.

5. Aluminium alloy strip or sheet according to any one of claims 1 to 4, characterized in that the aluminium alloy strip or sheet has a Si / Fe ratio of 0.45 < Si / Fe < 1.5 preferably 0.75 < Si / Fe < 1.

25.

6. Aluminium alloy strip or sheet according to any one of claims 1 to 5, characterized in that ZI / ZI 241192WO 6 February 2026 the aluminium alloy strip or sheet has an electrical conductivity of at least 28 MS / m, preferably at least 30.0 MS / m, more preferably at least 31.0 MS / m.

7. Aluminium alloy strip or sheet according to any one of claims 1 to 6, characterized in that the aluminum alloy strip or sheet has a yield strength R P 0.2 of at least 140 MPa, preferably at least 160 MPa.

8. Aluminium alloy strip or sheet according to any one of claims 1 to 7, characterized in that the aluminium alloy strip or sheet has an elongation at break Aso of at least 4%, preferably at least 6%, or at least Aso > 8%.

9. Aluminium alloy strip or sheet according to any one of claims 1 to 8, characterized in that the aluminium alloy strip or sheet has a primary aluminium content of a maximum of 80%, preferably a maximum of 70% or preferably a maximum of 60%.

10. Aluminium alloy strip or sheet according to any one of claims 1 to 9, characterized in that the aluminium alloy strip or sheet has a thickness of 0.5 mm to 10 mm, preferably 0.75 mm to 9 mm or preferably 1 mm to 8 mm.

11. Aluminium alloy strip or sheet according to any one of claims 1 to 10, characterized in that the aluminium alloy strip or sheet has a cold-worked and re-annealed condition H2X, H3X or H4x, preferably the cold-worked and re-annealed condition H22, H24, H26, H28, H32, H34, H36, H38 or H42, H44, H46, H48. ZI / ZI 241192WO February 6, 202612. Use of an aluminum alloy strip or sheet according to one of claims 1 to 11, as an electrically conductive component, preferably in the form of a busbar.

13. Method for producing an aluminum alloy strip according to any one of claims 1 to 11, characterized in that - an aluminum melt is cast into an aluminum alloy strip through a continuous casting process, preferably by casting rollers, - the aluminium alloy strip is rolled to its final thickness by cold rolling and - is subjected to a state annealing.

14. Method according to claim 13, characterized by the fact that cold rolling is carried out without intermediate annealing, wherein the degree of cold rolling before the final annealing is between 12% and 90%, preferably between 20% and 80%, more preferably between 30% and 70%.

15. Method according to one of claims 13 or 14, characterized by the fact that the final annealing is carried out at a peak metal temperature (PMT) T of 310 °C < T < 400 °C, preferably 325 °C < T < 390 °C, more preferably 350 °C < T < 380 °C, wherein the holding time t at PMT < 24 h, preferably 1 min < t < 24 h, more preferably 5 min < t < 22 h, wherein preferably a coil annealing is carried out.

16. Method according to any one of claims 13 to 15, characterized by the fact that the cooling rate during continuous casting above 340°C is at least 75°C / s, preferably at least 100°C / s, more preferably at least 125°C / s. ZI / ZI 241192WO February 6, 202617. Method according to one of claims 13 to 16, characterized by the fact that For the provision of an aluminium melt, a primary aluminium content of a maximum of 80%, preferably a maximum of 70% and particularly preferably a maximum of 60% is used. ZI / ZI 241192WO February 6, 2026

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