Method for producing an organically coated flat metal product

Abstract

The invention relates to a method for producing an organically coated metal flat product (1') according to claim 1.

Description

[0001] The invention relates to a method for producing an organically coated metal flat product.

[0002] The process for coating flat metal products, such as steel or aluminum flat products, with an organic coating, as well as the corresponding coil coating systems for carrying out the process, are state-of-the-art and are known in the industry as "coil coating" or "roller coating." Directly heated drying or convection furnaces have become established in practice for drying and / or baking the organic coatings. These are typically fed with fossil fuels, such as natural gas, and / or metallurgical gases. Direct combustion of hydrogen as fuel gas or hydrogen components in the fuel gas results in higher furnace humidity and / or a higher water vapor partial pressure in the furnace atmosphere as a result of the combustion reactions with air and / or oxygen compared to conventional natural gas combustion.Due to the higher water vapor partial pressure, unwanted water ingress cannot be ruled out, which can lead to deficiencies in the finished product. It is known that water vapor from the atmosphere diffuses into the matrix of an organic coating before, during, and after the drying process. During the drying process, water influences the crosslinking kinetics, for example, in the crosslinking of polyester resins with melamine derivatives.

[0003] The drying / baking oven is usually divided into different zones, each of which can be directly heated with at least one burner. During the drying / baking process, the flat metal product coated with the organic coating is passed through the different zones of the drying / baking oven essentially without contact within 10 to 120 seconds. There can be three, four, or more than four zones, for example, limited to a maximum of ten. Each zone can be individually assigned a specific temperature. For example, the first zone, or within the first zones, is set to a lower temperature than the temperature in the last zone in order to keep the atmospheric concentration of the solvents, which are expelled from the organic coating as a result of the thermal action, within the non-explosive range.

[0004] As part of the globally demanded decarbonization, plants powered by fossil fuels are to be converted or converted to more environmentally friendly fuels or energy sources, such as hydrogen, in order to reduce or ultimately avoid the use of fossil energy.

[0005] Decarbonization requires a reduction in the use of fossil fuels and energy sources and, in turn, a reduction in CO2 emissions.

[0006] If, for example, air or ambient air is used as an oxidizing agent for the direct combustion of the fuel, it is subject to high fluctuations in relative humidity due to weather conditions, so that the relative humidity of the air can also have a significant influence on combustion and thus lead to a higher water vapor partial pressure in the combustion gas.

[0007] The object of the present invention is to further develop the process for producing an organically coated metal flat product in such a way that it allows the use of any fuel, in particular hydrogen-containing fuels, thus reducing any negative influence on the organic coatings.

[0008] This object is achieved by a method having the features of claim 1. Further embodiments are described in the subclaims.

[0009] The teaching of the invention relates to a method for producing an organically coated metal flat product, comprising the steps: Providing a metal flat product; applying a liquid primer to the metal flat product by means of a roller application unit; drying the primer on the metal flat product in a directly heated drying oven or in at least one directly heated zone of a drying oven; either applying an organic topcoat to the metal flat product by means of a roller application unit;Baking the topcoat on the flat metal product in a directly heated baking oven or in at least one directly heated zone of a baking oven, wherein the drying oven and / or the baking oven or the at least one zone has at least one burner which is operated with a fuel gas and an oxygen-containing gas, which are burned to form a combustion gas, wherein, depending on the composition of the fuel gas and the composition of the oxygen-containing gas, the combustion gas has a composition with a water vapor partial pressure; or applying an organic film to the flat metal product. ;

[0010] Alternatively, a single-layer coating can be applied. Typically, the top and bottom surfaces of the flat metal product are coated. Combinations of foil lamination and painting are also possible.

[0011] It is essential for the invention that a gas is additionally introduced or added into the drying oven and / or the curing oven or into the at least one directly heated zone and mixed with the combustion gas in such a way that a water vapor partial pressure is established in the oven atmosphere of the oven or the at least one directly heated zone which is lower than the water vapor partial pressure of the combustion gas.

[0012] The additional gas introduced to "thin" the furnace atmosphere can advantageously lower the water vapor partial pressure and thus reduce the furnace humidity. This can reduce the risk of harmful water ingress, regardless of the fuel used.

[0013] The determination or recording of a water vapor partial pressure in a furnace atmosphere is familiar to those skilled in the art. This can be done, for example, by measuring the dew point using suitable measuring devices.

[0014] The gas used for introduction (and mixing) is preferably a gas with low / free water vapor and / or low / free hydrogen in order to achieve a reduction in the water vapor partial pressure or furnace humidity.

[0015] Low in water vapor means a water or water vapor content in the gas to be added of a maximum of 15.0 vol.%, in particular a maximum of 10.0 vol.%, preferably a maximum of 8.0 vol.%, more preferably a maximum of 5.0 vol.%, more preferably a maximum of 3.0 vol.%, more preferably a maximum of 1.50 vol.%, and in particular > 0.10 vol.%. Water vapor-free means that either no water or water vapor is present, or that the gas to be added may contain traces of up to a maximum of 0.10 vol.%.

[0016] Low-hydrogen content means a hydrogen content in the gas to be added of a maximum of 7.0 vol.%, in particular a maximum of 5.0 vol.%, preferably a maximum of 4.0 vol.%, preferably a maximum of 2.50 vol.%, more preferably a maximum of 1.0 vol.%, more preferably a maximum of 0.50 vol.%, and in particular >0.10 vol.%. Hydrogen-free means that either no hydrogen is present or the gas to be added may contain traces of up to a maximum of 0.10 vol.%.

[0017] The invention can be applied to existing, conventionally used fuel gases. A switch from a fossil fuel (natural gas) or, in particular, metallurgical gases as fuel to an alternative, hydrogen-containing fuel in a drying kiln and / or a curing kiln, or in at least one directly heated zone of a drying kiln and / or in at least one directly heated zone of a curing kiln in a coil coating line, results in a changed kiln atmosphere. When hydrogen-containing fuels are burned, a larger amount of water vapor is generated than when natural gas is used, resulting in a higher water vapor partial pressure in the kiln atmosphere. This would adversely affect the coating and could lead to significant quality losses or even total product failure.

[0018] Decarbonization in the application case of drying a primer and / or baking a topcoat on an organically coated metal flat product in a directly heated oven or in at least one directly heated zone of an oven in a coil coating line would therefore not only be a simple switch from fossil to non-fossil fuels, but would also involve a complex manipulation of the product parameters.

[0019] An increase in hydrogen in the fuel gas and thus an increase in the water vapor partial pressure in the resulting combustion gas should be counteracted by "diluting" the combustion gas by targeted mixing with a gas in order to create a furnace atmosphere that has a lower water vapor partial pressure compared to the (pure) combustion gas, in particular a furnace atmosphere can be created that approximately corresponds to a conventional furnace atmosphere, for example one fired with natural gas, or even with a lower furnace humidity, in order to avoid having to unnecessarily change the existing process chain and to be able to essentially retain the standard process.

[0020] By means of the measure according to the invention, a furnace atmosphere can be set in the directly fired drying furnace and / or in the directly fired curing furnace or in at least one directly heated zone of a drying furnace and / or in at least one directly heated zone of a curing furnace, which can have a low water vapor partial pressure or a low furnace humidity (compared to the pure combustion gas), regardless of which fuel gas is used for firing.

[0021] According to one embodiment, hydrogen can be used in the fuel gas for the drying oven and / or the curing oven or the at least one directly heated zone of the drying oven and / or the at least one directly heated zone of the curing oven in a proportion of at least 10 vol. %. In particular, hydrogen can be contained in the fuel gas in a proportion of at least 20 vol. %. Preferably, hydrogen can be contained in the fuel gas in a proportion of at least 40 vol. %. Preferably, hydrogen can be contained in the fuel gas in a proportion of at least 60 vol. %. Particularly preferably, hydrogen can be contained in the fuel gas in a proportion of at least 80 vol. %. More preferably, hydrogen can be contained in the fuel gas in a proportion of at least 98 vol. % This embodiment comprises, for example, a 100% use of hydrogen, in other words, the fuel gas consists of hydrogen, with impurities in the fuel gas up to 0.5 vol.-%, in particular up to 0.2 vol.%, preferably less than 0.1 vol.%, are permitted, whereby impurities cannot be avoided technically or only with high equipment expenditure.

[0022] The hydrogen used at least in part in the fuel gas can, for example, be produced and provided in water electrolysis using renewable energies such as wind, water, sun, biogas and / or geothermal energy.

[0023] If the fuel gas does not consist entirely of hydrogen, it may contain, in addition to hydrogen, further proportions of methane (CH 4 ) and / or carbon monoxide (CO) to give 100 vol.%, together with impurities which are permitted up to 0.5 vol.%, in particular up to 0.2 vol.%, preferably less than 0.1 vol.%.

[0024] For example, when using natural gas, the proportions of the main component methane can vary and thus also include other components such as ethane, propane, ethylene and butane individually or in combination.

[0025] The oxygen required for combustion can also be generated and provided by electrolysis using renewable energies (sun, wind, water, etc.).

[0026] The gas, which in particular is low in / free from water vapor and / or low in / free from hydrogen, for introduction and thus for mixing with the combustion gas can contain or consist of nitrogen (N 2 ), argon (Ar), carbon dioxide (CO 2 ), carbon monoxide (CO) or a mixture thereof. For example, inert gases are used. Other gases or mixtures of gases which contain no or relatively low proportions of water and / or water vapor and / or hydrogen or no or relatively low proportions of hydrogen compounds and which are suitable for a drying oven for drying a primer and / or a baking oven for baking a top coat or for at least one directly heated zone of a drying oven and / or for at least one directly heated zone of a baking oven can also be used accordingly.

[0027] Alternatively, air (ambient air), preferably dry air, can also be used.

[0028] The so-called PMT (Peak Metal Temperature) represents the highest temperature reached on the coating surface and is preferably determined using a pyrometer or other suitable means.

[0029] The PMT for drying a primer-coated flat metal product in the drying oven of a coil coating line is generally between 100 °C and 300 °C, in particular between 120 °C and 285 °C, and preferably between 150 °C and 270 °C. This temperature refers to the temperature of the coated flat metal product, or rather the coating. The oven atmosphere temperature in the drying oven is certainly higher.

[0030] The PMT for curing a topcoat-coated metal flat product in the curing oven of a coil coating line is generally between 150 °C and 350 °C, in particular between 170 °C and 320 °C, and preferably between 190 °C and 270 °C. This temperature refers to the temperature of the coated metal flat product, or rather the coating. The furnace atmosphere temperature in the curing oven is certainly higher.

[0031] The strip coating system is preferably designed to be continuous.

[0032] The coil coating line is preferably equipped with a horizontal drying oven and / or a horizontal curing oven.

[0033] The process for roller application of a primer and topcoat, and thus the setup of a coil coating system, is state-of-the-art and therefore familiar to experts. Application after the primer has dried using an organic film is also standard.

[0034] The oxygen-containing gas for operating the burner can be air, for example, ambient air, oxygen, or a combination of air and oxygen. The oxygen-containing gas and / or the fuel gas can be preheated before being fed to combustion to increase energy efficiency, for example, to at least 200 °C, in particular to at least 300 °C, preferably to at least 400 °C. Preheating can, for example, be limited to a maximum of 500 °C. Preheating the fuel gas and / or the oxygen-containing gas can lead to an increase in the adiabatic flame temperature.

[0035] "Flat metal product" refers to sheets or similarly manufactured strips as rolled products made of an aluminum material (flat aluminum product) or a steel material (flat steel product), which can be either hot-rolled, i.e., a hot-rolled strip, or preferably cold-rolled, i.e., a cold-rolled strip.

[0036] In order to be able to reduce the water vapor partial pressure or the furnace humidity in the furnace atmosphere, a flow rate of the gas to be introduced should be set as a function of the volume of the furnace chamber into which the gas is introduced, such that at least the volume of the furnace chamber can be filled in one hour, in particular at least 1.5 times the volume of the furnace chamber per hour, preferably at least 2 times the volume of the furnace chamber per hour, preferably at least 2.5 times the volume of the furnace chamber per hour.The flow rate is set and limited to a maximum of 50 times the volume of the furnace chamber per hour, in particular a maximum of 25 times the volume of the furnace chamber per hour, preferably a maximum of 15 times the volume of the furnace chamber per hour, preferably a maximum of 10 times the volume of the furnace chamber per hour, in order, for example, to avoid adversely affecting the thermal energy from the resulting combustion gas. Knowing the volume, it can then be converted to common values in liters per second or per minute, or even cubic meters per minute or per hour.

[0037] In order not to negatively influence the energy of the combustion gas and / or even to increase energy efficiency, it can be advantageous if, according to one embodiment, the gas, in particular one with a low / free water vapor content and / or a low / free hydrogen content, is heated before being introduced. In order to essentially maintain the energy level of the combustion gas, the gas, in particular one with a low / free water vapor content and / or a low / free hydrogen content, is heated to a temperature which preferably corresponds to the temperature of the combustion gas between + / - 300 °C. The temperature can thus correspond to a temperature window between minus and plus 300 °C relative to the temperature of the combustion gas. The temperature of the combustion gas can be measured using means known to those skilled in the art.

[0038] In order to economically utilize the exhaust gas discharged from the drying oven and / or curing oven or at least one zone of the oven of a coil coating line, a mixed gas consisting of combustion gas and introduced gas, in particular gas that is low in / free from water vapor and / or low in / free from hydrogen, it may be advantageous to use part or all of the exhaust gas to heat the gas, in particular gas that is low in / free from water vapor and / or low in / free from water vapor, before introducing it. In this case, too, the means for exhaust gas utilization or heat transfer are known to those skilled in the art.

[0039] Alternatively or additionally, the oxygen-containing gas and / or the fuel gas can also be heated accordingly.

[0040] Alternatively or in addition to the use of exhaust gases, the (additional) heating can also be carried out by other means, for example electrically, if a higher temperature level is required compared to the exhaust gas temperature.

[0041] Furthermore, the temperature of the burner flame also influences the temperature of the furnace atmosphere. The combustion temperature with ambient air and natural gas is approximately 1970 °C, and with ambient air and hydrogen it is approximately 2130 °C. Combustion with oxygen and natural gas is approximately 2860 °C, and with oxygen and hydrogen it is approximately 3080 °C.

[0042] The burner is operated with an air ratio between 1.0 and 1.25 in order to take into account the ratio n O 2 / n fuel gas with regard to the combustion gas in order to avoid a mixture that is too rich and CO formation, but also a mixture that is too lean in connection with a high combustion temperature and undesirable NO x formation, so that the air ratio is limited in particular to a maximum of 1.22, preferably to a maximum of 1.17, preferably to a maximum of 1.13.

[0043] If, for example, a flat steel product is used, it can preferably be provided with a metallic coating. The flat steel product can preferably be coated with a zinc-based coating, particularly preferably by hot-dip coating. In addition to zinc and unavoidable impurities, the metallic molten bath can contain or consist of additional elements such as aluminum with a content of up to 15 wt.%, in particular up to 10 wt.%, preferably up to 8 wt.%, preferably up to 5 wt.% and / or magnesium with a content of up to 15 wt.%, in particular up to 10 wt.%, preferably up to 8 wt.%, preferably up to 5 wt.%. If improved corrosion protection is required, the metallic molten bath can contain or consist of magnesium with a content of at least 0.3 wt.%, in particular of at least 0.6 wt.%, preferably of at least 0.9 wt.%.Additionally or alternatively, aluminum may be present in addition to magnesium in a content of at least 0.1 wt.%, in particular at least 0.3 wt.%, for example to improve the bonding of the metallic coating to the flat steel product and, in particular, to substantially prevent the diffusion of iron from the substrate into the coating during heat treatment of the coated flat steel product, so that, for example, good adhesive properties can be ensured. The thickness of the metallic coating per side can be adjusted to between 1.5 and 60 µm, in particular between 2 and 50 µm, preferably between 3 and 30 µm, using known stripping nozzles arranged above the molten bath.

[0044] If the metallic melt bath contains or consists of magnesium within the aforementioned limits, aluminum within the aforementioned limits and the remainder zinc along with unavoidable impurities, the resulting metallic coating on the flat steel product is known in the professional world as zinc-magnesium (ZM) or Zn-Al-Mg.

[0045] In a preferred variant, the aluminum content in the metallic melt bath is 1.1 to 8 wt.%, in particular 1.2 to 5 wt.%.

[0046] In a preferred variant, the magnesium content in the metallic melt bath is 1.1 to 8 wt.%, in particular 1.2 to 5 wt.%.

[0047] The coating may also contain only zinc with small amounts of aluminum in addition to unavoidable impurities, also known by the designation "Z" in technical circles.

[0048] As unavoidable impurities, for example, elements from the group silicon, antimony, lead, titanium, calcium, manganese, tin, lanthanum, cerium and chromium may be contained individually or in combination with a total of up to 0.5 wt.%, in particular up to 0.3 wt.% in the metallic melt bath.

[0049] Alternatively, the flat steel product may be coated with a zinc-based coating by electrolytic deposition, known in technical circles as "ZE".

[0050] The thickness of the metallic coating per side can be set between 1 and 60 µm, in particular between 2 and 50 µm, preferably between 3 and 30 µm.

[0051] The invention is explained in more detail using the following embodiments in conjunction with the drawing.

[0052] The drawing shows the invention using the example of a schematic illustration. Figure 1shows a schematic diagram of a strip coating system (100) for producing an organically coated flat metal product (1'). A flat metal product (1) in the form of a coil is provided. This can be an aluminum flat product or preferably a steel flat product, preferably coated with a zinc-based coating. The thus provided flat metal product (1) in coil form is placed on a decoiler of the strip coating system (100) and unwound. The subsequent process chain is shown in a simple configuration as standard, but may deviate from this depending on the system configuration. The unwound flat metal product (1) can pass through a straightening machine known to those skilled in the art but not shown. The unwound flat metal product passes through: a cleaning unit (2) for cleaning the surfaces; a pretreatment unit (3) for activating the cleaned surfaces; a roller application unit (4) for applying a liquid primer to the flat metal product (1); a directly heated drying oven (5) or a drying oven (5) with at least one directly heated zone for drying the primer on the flat metal product (1); optionally, a cooling unit (not shown); a roller application unit (6) for applying a liquid organic topcoat to the flat metal product (1); a directly heated baking oven (7) or a baking oven (7) with at least one directly heated zone for drying the primer on the flat metal product (1); optionally, a cooling unit (not shown); a post-treatment unit (8) for laminating, for example, with a temporary protective film; finally, the organically coated flat metal product (1') is wound into a coil.

[0053] The drying oven (5) and / or the curing oven (7) or the at least one zone of the drying oven (5) and / or the curing oven (7) has at least one burner (11) which is operated with a fuel gas (11.3) and an oxygen-containing gas (11.4), which are burned to form a combustion gas (11.9), wherein depending on the composition of the fuel gas (11.3) and the composition of the oxygen-containing gas (11.4), the combustion gas (11.9) has a composition with a water vapor partial pressure, cf. Figure 2 ,which shows a schematic cross-section through a drying oven (5) and / or curing oven (7). For the drying oven (5) and / or the curing oven (7) or the at least one directly heated zone of the drying oven (5) and / or the at least one directly heated zone of the curing oven (7), hydrogen is used in the fuel gas (11.3) with a proportion of at least 10 vol.%. Furthermore, a gas (11.5) is additionally introduced into the drying oven (5) and / or the curing oven (7) or into the at least one directly heated zone and mixed with the combustion gas (11.9) in such a way that a water vapor partial pressure is established in the oven atmosphere (10.1) of the oven (5, 7) or the at least one directly heated zone, which partial pressure is lower than the water vapor partial pressure of the combustion gas (11.9).

[0054] Hydrogen can be provided partially or entirely as fuel gas (11.3). Additionally, at least one means (11.1) is provided for introducing a preferably water vapor-free and / or hydrogen-free gas (11.5). The hydrogen used at least partially in the fuel gas can be generated and provided, for example, in water electrolysis using renewable energies such as wind, water, solar, biogas, and / or geothermal energy; this is not shown here.

[0055] The means comprises at least one inlet nozzle (11.1), which is individually orientable and / or adjustable, for example, in spatial direction. This allows, for example, the inflow direction (11.10) of the introduced gas (11.5) to be specifically influenced such that the impulse forces a forced flow within the furnace (5, 7) and thus a mixture with the combustion gas (11.9).

[0056] For example, in order to orientate oneself on a conventionally known furnace atmosphere with natural gas combustion and to adjust this despite the use of hydrogen in the fuel gas, the volume of the fuel gas (11.3) and the volume of the introduced gas (11.5) can be determined in the usual way, in particular depending on the volume of the drying furnace (5) and / or the curing furnace (7) or the at least one directly heated zone. The volume of the fuel gas (11.3) depends on the heat output required for drying and / or curing and is based on a control of the material temperatures required for drying and / or curing. The volume of the gas to be introduced (11.5) is determined from the volume of the fuel gas (11.3) and thus from the chemical elements resulting from the combustion and the volume of the furnace (5, 7), corrected by corresponding analytical measurements of the furnace atmosphere (10.1).

[0057] Before being introduced (11.10), the preferably water vapor-poor / free and / or hydrogen-poor / free gas (11.5) can be heated. The oxygen-containing gas (11.4), not shown, can also be preheated before combustion. An exhaust gas (11.7) can be discharged from the furnace (5, 7), which can be used partially or completely to heat the preferably water vapor-poor / free and / or hydrogen-poor / free gas (11.5) by means of a suitable heat exchanger (11.6). Alternatively or additionally, the preferably water vapor-poor / free and / or hydrogen-poor / free gas (11.5) can be heated, in particular additionally, for example by an electric heating device (11.8), shown in dashed lines, with which a temperature increase of the preferably water vapor-poor / free and / or hydrogen-poor / free gas (11.5) above the temperature of the exhaust gas (11.7) would also be possible.

[0058] With the furnace atmosphere (10.1) adjusted according to the invention, drying of the primer applied to the flat metal product (1) and / or baking of the top coat applied to the flat metal product (1) is possible without disadvantages despite the use of non-fossil fuels if hydrogen is used in proportions between 10 and 100 vol.% in the fuel gas (11.3).

[0059] Not shown, the invention can also be used in conventional operation, in particular to maintain an atmosphere with a constant water vapor partial pressure or furnace humidity by introducing the additional gas, regardless of which fuel gas and which relative humidity of the ambient air used for combustion is used.

Claims

1. A method for producing an organically coated flat metal product (1'), comprising the steps of: - providing a flat metal product (1); - applying a liquid primer to the flat metal product (1) by means of a roller application unit (4); - drying the primer on the flat metal product (1) in a directly heated drying oven (5) or in at least one directly heated zone of a drying oven (5); either - applying a liquid organic topcoat to the flat metal product (1) by means of a roller application unit (6); - baking the top coat on the flat metal product in a directly heated baking oven (7) or in at least one directly heated zone of a baking oven (7), wherein the drying oven (5) and / or the baking oven (7) or the at least one zone has at least one burner (11) which is operated with a fuel gas (11.3) and an oxygen-containing gas (11.4), which are combined to form a combustion gas (11.9) are burned, wherein, depending on the composition of the fuel gas (11.3) and the composition of the oxygen-containing gas (11.4), the combustion gas (11.9) has a composition with a water vapor partial pressure; Or - applying an organic film to the flat metal product (1); . characterized in that a gas (11.5) is additionally introduced into the drying oven (5) and / or the curing oven (7) or into the at least one directly heated zone and mixed with the combustion gas (11.9) in such a way that a water vapor partial pressure is established in the oven atmosphere (10.1) of the oven (5, 7) or of the at least one directly heated zone which is lower than the water vapor partial pressure of the combustion gas (11.9).

2. The method according to claim 1, wherein hydrogen is used in the fuel gas (11.3) with a proportion of at least 10 vol.% for the drying oven (5) and / or the baking oven (7) or the at least one directly heated zone of the drying oven (5) and / or the at least one directly heated zone of the baking oven (7).

3. Method according to one of the preceding claims, wherein a gas with / without water vapor and / or with / without hydrogen is used as the gas (11.5) for introduction.

4. Method according to one of the preceding claims, wherein a flow rate of the gas (11.5) is adjusted as a function of the volume of the furnace chamber into which the gas (11.5) is introduced, such that at least the volume of the furnace chamber can be filled in one hour and at most 50 times the volume of the furnace chamber per hour.

5. Method according to one of the preceding claims, wherein the gas (11.5) is heated before being introduced into the drying oven (5) and / or the baking oven (7) or into the at least one zone of the drying oven (5) and / or the baking oven (7).

6. The method according to claim 5, wherein the heating is carried out to a temperature which corresponds to the temperature of the combustion gas (11.9) between + / - 300 °C.

7. Method according to one of the preceding claims, wherein the burner (11) is operated with an air ratio between 1.0 and 1.

25.

8. Method according to one of the preceding claims, wherein the flat metal product (1) is a flat steel product.

9. The method according to any one of claims 1 to 7, wherein the metal flat product (1) is an aluminum flat product.

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