Coated steel sheet with ZM coating, and steel sheet component produced therefrom

Abstract

The invention relates to a coated steel sheet having a ZM coating and a layer weight ranging from 200 to 1000 g / m2, containing, in addition to zinc and unavoidable impurities, the additional elements aluminum, in a weight percentage of 0.5 to 8.0 wt.%, and magnesium, in a weight percentage of 0.5 to 8.0 wt.%, in the coating, the ZM coating comprising or consisting of zinc grains (Z) and a eutectic (E). The invention also relates to a steel sheet component produced from the steel sheet.

Description

[0001] ThyssenKrupp Steel Europe AG 237082P10WO

[0002] December 4, 2025 1 / 17

[0003] Coated steel sheet with zinc coating and steel sheet component manufactured from it

[0004] The invention relates to a coated steel sheet with a zinc coating and a coating weight between 200 and 1000 g / m² 2 The invention comprises, in addition to zinc and unavoidable impurities, the elements aluminum with a content of 0.5 to 8.0 wt.% and magnesium with a content of 0.5 to 8.0 wt.% in the coating, wherein the zinc-magnesium coating comprises or consists of zinc grains and a eutectic. Furthermore, the invention relates to a steel sheet component manufactured from the steel sheet.

[0005] In the steadily growing market for solar mounting systems, the materials used are exposed to high levels of corrosion. Typically, service lives of at least 25 years under so-called outdoor weathering conditions must be guaranteed. It is therefore desirable to use coatings for this application that exhibit high and long-lasting corrosion resistance. Zinc oxide coatings are particularly suitable for this purpose. These can be efficiently applied using a hot-dip coating process.

[0006] In principle, zinc-based coatings on a substrate, especially a steel substrate, offer the advantage of active cathodic corrosion protection. This is due to the negative electrochemical corrosion potential of the substrate, which is essentially a carbon steel. In addition to this, zinc-based coatings also provide passive corrosion protection in the form of a barrier due to a more pronounced outer oxide layer.

[0007] The microscopic structure of a zinc coating typically consists of two core elements. Firstly, the layer contains zinc-rich globular grains (hereinafter referred to as "zinc grains"). Between the zinc grains are regions of eutectic composition (hereinafter referred to as the "eutectic zone"), which geometrically fill the gaps between the zinc grains.

[0008] If a zinc alloy coating is exposed to corrosive stress, the corrosive interaction is intensified in the eutectic regions, which are more susceptible to corrosion than the zinc grains. A technical weakness of the zinc alloy is therefore the spatially localized erosion within the eutectic zone, which can compromise the mechanical integrity of the entire coating. If the eutectic zone is excessively worn away, there is a risk of zinc grains breaking off locally and losing their adhesion to the remaining zinc alloy coating. This leads to ThyssenKrupp Steel Europe AG 237082P10WO

[0009] December 4, 2025 2 / 17 exposed areas on the base material and consequently a local failure of the corrosion protection.

[0010] To mitigate this problem and thus reduce the local failure probability of a ZM coating, a coating structure is desirable that can mitigate the weaknesses of the ZM coating described above.

[0011] EP 4 079 920 Al discloses a zinc-coated steel sheet with improved formability, wherein the zinc coating contains, in addition to 1.5-2.3 wt.% Al and 1.2-1.8 wt.% Mg, the rare earth elements La and Ce in total at 0.01-0.08 wt.%, as well as a total of 0.01-0.08 wt.% Cu, Cr and / or Ni. The fine grain structure and improved formability are attributed to the targeted addition of La and Ce as well as Cu, Cr and / or Ni.

[0012] The object of the present invention is to provide steel sheets, or steel sheet components made from them, particularly for solar mounting structures, with improved corrosion protection. This corrosion protection should be retained even after the steel sheets have been formed into components and preferably after mechanical damage to the surface of the zinc coating. In particular, during forming processes that cause cracking in the corrosion protection, i.e., cracks in the corrosion protection layer, the propagation of cracks to the substrate should be reduced or prevented. Furthermore, long-term use under corrosive conditions in the field should be enabled, preferably as pile foundations for ground applications and as primary and / or secondary support structures.

[0013] The problem is solved with regard to a coated steel sheet with the features of claim 1, with regard to a method for producing a ZM coating with the features of claim 8, with regard to a coated steel sheet component with the features of claim 11 and with regard to a use with the features of claim 15.

[0014] The first teaching of the invention relates to a coated steel sheet with a zinc coating and a coating weight on both sides of between 200 and 1000 g / m². 2 , i.e., between 100 and 500 g / m² 2per side, which, in addition to zinc and unavoidable impurities, comprises the elements aluminum with a content of 0.5 to 8.0 wt.% and magnesium with a content of 0.5 to 8.0 wt.% in the coating, wherein the zinc-mineral coating comprises or consists of zinc grains and eutectic material. According to the invention, the zinc-mineral coating is applied by hot-dip fusion and, after the melt bath, stripped off in such a way that a coating is formed on ThyssenKrupp Steel Europe AG 237082P10WO

[0015] December 4, 2025

[0016] 3 / 17 forms both sides of the substrate, with each side of the substrate having a coating of at least 100 g / m² 2 , in particular of at least 150 g / m² 2 , preferably of at least 200 g / m² 2 exhibits.

[0017] The mass ratio AI:Mg is preferably 0.8-1.8, particularly 1.0-1.5 and especially preferably 1.0-1.2.

[0018] In addition to the zinc grains, the ZM coating may also contain at least one other phase selected from a ternary eutectic Zn / Al / MgZn2 structure, a binary eutectic Zn / MgZn2 structure, a binary eutectic Zn-Al structure and a single-phase MgZn2 structure.

[0019] The essential aspect of the invention is that in a vertical section through the coated steel sheet in a scanning electron microscope (SEM) image, a measuring surface having a rectangle with a long side of 200 pm and a short side of 14 pm, preferably 17 pm or 20 pm, particularly preferably 22 pm, in particular 25 pm, is stretched within the zinc coating in such a way that the long side of the rectangle is aligned parallel to the sheet plane, wherein the zinc grains occupy an area fraction of at least 75% in the measuring surface.

[0020] The inventors have surprisingly discovered that a high printing weight of between 200 and 1000 g / m² on both sides results in a higher density.2 , in particular at least 230, 250 g / m² 2 , preferably at least 280, 300 g / m² 2 preferably at least 320, 350 g / m² 2 , particularly preferably at least 370, 400 g / m² 2 , and especially up to 900, 800 g / m² 2 , preferably up to 720, 650 g / m² 2With a finely tuned process control in the hot-dip coating process, a preferably multi-layered grain structure of the zinc grains arranged in the zinc coating can be achieved. For example, with an adequately controlled cooling rate of the steel sheet after exiting the zinc melting pot and the associated solidification behavior of the zinc melt on the steel sheet, a multi-layered arrangement of sufficiently small zinc grains can be obtained. This ensures that even after the eutectic dissolves, there is no local complete failure of the zinc coating due to the detachment of individual large zinc grains. Instead, due to the overall multi-layered grain structure, initially only smaller portions of the coating, particularly near-surface portions, detach, while the underlying zinc grains continue to perform their corrosion-protective function. Therefore, the zinc grains occupy a surface area of ​​at least 75% of the measuring area.ThyssenKrupp Steel Europe AG 237082P10WO.

[0021] December 4, 2025

[0022] 4 / 17

[0023] In addition, the zinc grains can cause cracks that arise during forming in the coating to be slowed down, or in the best case even stopped, at the phase boundaries between the zinc grain and the eutectic.

[0024] Cracks propagating through the softer zinc grains exhibit a lower stress intensity factor at the phase boundary, making it more difficult for them to penetrate into the harder eutectic. Zinc grains embedded in eutectic phases thus impede crack propagation and, at best, halt it. Coatings consisting primarily of eutectic phases therefore do not offer any crack inhibition. Cracks in the harder eutectic phases exhibit a higher stress intensity factor at the crack tip than cracks in the softer zinc phases. The random, staggered distribution of the fine zinc grains across multiple layers can significantly reduce the risk of cracking down to the substrate. This also prevents spalling that exposes the substrate.

[0025] Cracks in the zinc coating can be detected qualitatively and guantatively using a microscope (e.g., SEM). A reduction in the number and extent of cracks, when evaluated under the microscope, indicates that the crack tip does not reach the substrate and / or, in opening mode I, the crack opening perpendicular to the crack plane is smaller, in each case compared to a zinc coating in which the zinc grains occupy less than 75% of the surface area.

[0026] The measuring surface has a long side of 200 pm, preferably 210 pm, particularly preferably 220 pm, and a short side of 14 pm, preferably 17 pm, particularly preferably 20 pm or 22 pm, and especially 25 pm, wherein the long side of the rectangle is aligned parallel to the sheet plane and the entire measuring surface is arranged within the ZM coating on the SEM image. The sheet plane (or substrate surface) is considered to be the surface of a flat sheet, without regard to structures that contribute to waviness or roughness.

[0027] The surface layer weight is between 200 and 1000 g / m². 2 refers to both sides of the coated steel sheet, therefore 100-500 g / m² each. 2 per sheet side and thus corresponds approximately to a zinc coating thickness of between 14 pm and 80 pm per side. ThyssenKrupp Steel Europe AG 237082P10WO

[0028] December 4, 2025 5 / 17

[0029] In conventional hot-dip coating processes, the cooling of the zinc alloy melt is slowed, especially with high coating weights. This leads to grain growth with few, large grains, which would be counterproductive to the desired appearance of the zinc coating. Investigations have shown that the zinc alloy melt applied to the steel sheet should be cooled at a rate of > 15 °C / s, in particular > 22 °C / s or > 25 °C / s, preferably > 28 °C / s or > 30 °C / s, and preferably > 37 °C / s. The temperature of the steel sheet exiting the zinc alloy melt above the melt and, in particular, before the first deflection roller, can be measured, for example, using a pyrometer and / or thermal imaging camera.

[0030] Between the point where the coated strip exits the zinc melt and the first deflection roller, the cooling of the applied coating is divided into three phases: the first phase extends from the melt pool exit to the point at 1 / 3 of the strip's travel distance before the deflection roller; the second phase from the point at 1 / 3 to the point at 2 / 3 of the strip's travel distance; and the third phase from the point at 2 / 3 of the strip's travel distance to just before the first deflection roller. The strip surface temperature is preferably measured non-contact using pyrometers and / or thermal imaging cameras at the melt pool exit, at the 1 / 3 and 2 / 3 positions of the strip's travel distance, and before the deflection roller; the average cooling rate for each phase is determined from the temperature-time profiles.The cooling rate of the first phase is greater than 22°C, in particular greater than 25°C / s and preferably greater than 30°C / s, the cooling rate of the second phase is greater than 15°C / s, in particular greater than 20°C / s and preferably greater than 25°C / s, and the cooling rate of the third phase is greater than 5°C / s, in particular greater than 10°C / s and preferably greater than 15°C / s.

[0031] The three-phase cooling process defined between the exit of the coated strip from the zinc alloy melt and the first deflection roller fulfills different, complementary metallurgical functions. In the first cooling and early solidification phase, an iron-aluminum boundary layer (Fe-Al intermetallic phase) preferentially forms at the interface between the steel substrate and the zinc alloy coating. This layer acts as an effective adhesion promoter and suppresses the formation of brittle Fe-Zn phases. The deliberately high cooling rate in this zone simultaneously establishes a fine primary grain structure of the zinc-rich grains; grain growth is inhibited, thus preparing the desired, crack-resistant multi-layer grain architecture and preventing undesirable permeation of individual primary grains across the entire layer thickness. In the second cooling phase, the majority of the coating solidifies; at least 90% of the coating mass is hardened.ThyssenKrupp Steel Europe AG provides the 237082P10WO.

[0032] December 4, 2025

[0033] 6 / 17 The coating structure is essentially finalized: the grain size distribution of the zinc-rich grains, as well as the topology and area fraction of the eutectic regions, are determined. The specified cooling rate limits the area fraction of eutectic percolation to less than 5%, promotes a high area fraction of zinc grains, and thus stabilizes the desired microstructure. The third cooling phase ensures complete solidification of the coating and conditions the layer for the upcoming contact with the upper deflection roller. The defined cooling regime prevents local plastic deformation, indentations, or microcracking during roller contact; at the same time, thermal stresses are reduced, ensuring sufficient robustness of the solidified layer against mechanical contact in the cooling section.

[0034] A “percolating eutectic” exists when there is a continuous channel from the free coating surface edge to the iron-aluminum interface, without interruption by zinc grains or other phases (above the measurable resolution).

[0035] In the present invention, a fine, crack-inhibiting grain structure of the zinc coating is primarily achieved via a defined, measurable cooling regime between the melt bath exit and the first deflection roller. A multilayer arrangement of small zinc grains with a high surface area is obtained without the addition of rare earth metals or other additives. This reduces the complexity of the bath flow, improves reproducibility, and provides a clearly quantifiable microstructure that meets the mechanical and corrosive requirements (especially under bending and outdoor weathering conditions).

[0036] In a preferred embodiment, at most 5% of the zinc grains extend vertically across the entire local thickness of the zinc coating, thus essentially avoiding continuous primary grains. This promotes a crack-inhibiting, multi-layered grain architecture.

[0037] In a further preferred embodiment, the area fraction of continuous eutectic paths in the SEM measurement area defined above is at most 5%. A continuous eutectic path exists if a line perpendicular to the sheet plane, extending from the free coating surface to the iron-aluminum interface, passes exclusively through eutectic regions (without interruption by zinc-rich grains above the resolution limit). The proportion of percolating eutectic material is at most 5%. ThyssenKrupp Steel Europe AG 237082P10WO

[0038] December 4, 2025

[0039] 7 / 17

[0040] To preferentially avoid percolating eutectic channels, it is required that in the SEM measurement area defined above (200 pm × 14 pm), at most 5% of the percolation paths running perpendicular to the sheet plane through the zinc coating consist exclusively of eutectic material. Equally spaced test lines, oriented perpendicular to the sheet plane, are placed across the measurement area, preferably with a sampling interval of less than 1 pm. A test path is considered a "continuous eutectic path" if it passes exclusively through eutectic pixels from the free coating surface to the iron-aluminum interface, neglecting point interruptions below the resolution limit. The proportion of paths classified as continuously eutectic to the total number of test paths must be determined and must be less than 5%.This parameter reflects the fact that the zinc grains are arranged in several offset planes and that the eutectic percolates over the entire layer thickness in at most 5% of cases.

[0041] The invention thus relates to a method for producing a zinc-metal coating which, in addition to zinc and unavoidable impurities, contains the elements aluminum with a content of 0.5 to 8.0 wt.% and magnesium with a content of 0.5 to 8.0 wt.%.-% in the coating, wherein the cured zinc coating comprises or consists of zinc grains and eutectic material, characterized in that, in a vertical section through the coated steel sheet in an SEM image, a measuring area having a rectangle with a long side of 200 pm and a short side of 14 pm is clamped within the zinc coating such that the long side of the rectangle is aligned parallel to the sheet plane, wherein the zinc grains occupy an area fraction of at least 75% in the measuring area, wherein a steel sheet is immersed in a molten bath which comprises or consists, in addition to zinc (residual) and unavoidable impurities, the elements aluminum with a content between 0.5 and 8.0 wt.% and magnesium with a content between 0.5 and 8.0 wt.%, a stripping of the liquid zinc melt on both sides by means of a stripping device to set a coating weight on both sides of 200 to 1000 g / m². 2The process is carried out, wherein the zinc alloy melt applied to the steel sheet is cooled at a rate of > 15 °C / s, in particular > 22 °C / s or > 25 °C / s, preferably > 28 °C / s or > 30 °C / s, preferably > 37 °C / s, wherein the temperature of the steel sheet exiting the zinc alloy melt above the zinc alloy melt, on the one hand, and in particular before the first deflection roller, on the other hand, can be detected, for example, by means of a pyrometer or thermal imaging camera. ThyssenKrupp Steel Europe AG 237082P10WO

[0042] December 4, 2025 8 / 17

[0043] The liquid zinc melt is preferably wiped off using slot nozzles to adjust a coating weight of 200 to 1000 g / m² on both sides. 2 .

[0044] The procedure may preferably additionally include, but is not limited to, one or more of the following steps in any sequence:

[0045] Mechanical pre- and / or post-processing, such as skin-passing to adjust a deterministic or stochastic surface structure or to improve flatness and evenness, or straightening.

[0046] Forming processes, such as bending, folding, deep drawing, roll forming or flanging, are preferably possible.

[0047] Preferred surface cleaning and activation is possible, for example by degreasing, pickling, mechanical brushing or fine polishing.

[0048] Conversion and passivation layers as well as organic coatings can preferably be applied.

[0049] Furthermore, tribological intermediate treatments are preferably carried out, for example by means of oiling or forming lubricants.

[0050] Preferred joining and connection techniques include resistance spot welding, laser welding, MAG / MIG, hard / soft soldering and / or bonding.

[0051] Where appropriate, cleaning, rinsing, and drying steps can be inserted between the aforementioned steps to ensure surface cleanliness and adhesion of subsequent layers or joining processes. The selection and sequence of these measures depend on the intended application (e.g., direct forming, painting, joining technology) and the required final performance (corrosion protection, formability, adhesion strength).

[0052] The zinc alloy coating, applied by hot-dip coating, comprises or consists of a zinc alloy containing, in addition to zinc (remaining) and unavoidable impurities, the elements aluminum with a content between 0.5 and 8.0 wt.% and magnesium with a content between 0.5 and 8.0 wt.%. The coating may contain impurities from the group consisting of Si, Sb, Bi, Zr, Ni, Cr, Pb, Ti, Ca, Mn, Sn, La, Ce, Fe, and Cr, in concentrations individually or cumulatively up to 0.5 wt.%, in particular up to 0.4 wt.%, preferably up to 0.3 wt.%, whereby, alternatively, the concentration of Fe may be higher due to diffusion. The remainder is zinc. Preferably, the zinc alloy coating is free of targeted additions of the elements La, Ce, Cu, Cr, and Ni, and each of these elements is present only as unavoidable impurities. ThyssenKrupp Steel Europe AG 237082P10WO

[0053] December 4, 2025 9 / 17

[0054] The coating contains impurities at most 0.05 wt.%. It preferably contains magnesium at least 0.8 wt.%, in particular at least 1.0 wt.%, preferably at least 1.1 wt.%, and aluminum at least 0.8 wt.%, in particular at least 1.0 wt.%. Alternatively, the coating may contain magnesium at most 8.0 wt.%, preferably at most 7.0 wt.%, particularly preferably at most 5.0 wt.%, in particular at most 4.0 wt.%, and aluminum at most 8.0 wt.%, preferably at most 7.0 wt.%, in particular at most 5.0 wt.%, in particular at most 4.0 wt.%.

[0055] In one embodiment, the zinc coating is applied by hot-dip coating in a melt bath, wherein the melt bath, in addition to zinc (residual) and unavoidable impurities, comprises aluminum with a content between 0.5 and 8.0 wt.% and magnesium with a content between 0.5 and 8.0 wt.%. Impurities in the melt bath may include elements from the group consisting of silicon, sab, bi, zr, nickel, chromium, lead, titanium, calcium, manganese, sulfur, larium, ceuracy, iron, and chromium, individually or cumulatively, up to 0.5 wt.%, in particular up to 0.4 wt.%, preferably up to 0.3 wt.%. The remainder is zinc. The melt bath preferably contains magnesium with a content of at least 0.8 wt.%, in particular at least 1.0 wt.%, preferably at least 1.1 wt.%, and aluminum with a content of at least 0.8 wt.%, in particular at least 1.0 wt.%. The melt bath contains magnesium with a maximum content of 8.0 wt.%, preferably a maximum of 7.0 wt.%.-%, particularly preferably of a maximum of 5.0 wt.%, in particular of a maximum of 4.0 wt.% and aluminium with a content of a maximum of 8.0 wt.%, preferably of a maximum of 7.0 wt.%, in particular of a maximum of 5.0 wt.%, in particular of a maximum of 4.0 wt.%.

[0056] In particular, to achieve a predetermined thickness of the zinc oxide coating, which in the solid or solidified state can range between 14 pm and 60 pm per side, the molten metal applied to the steel strip while still liquid is stripped off. This is accomplished by passing the steel strip coated with liquid molten metal through a stripping device after it has left the melt pool. The stripping device includes means, such as nozzles, especially slot nozzles, which act on both sides of the steel strip with a gaseous stripping medium to remove the liquid molten metal. The thickness of the zinc oxide coating can be adjusted, in particular, to at least 14 pm, preferably at least 17 pm, particularly preferably at least 20 pm or 22 pm, particularly at least 25 pm, particularly preferably at least 45 pm and a maximum of 80.0 pm, preferably a maximum of 60.0 pm, and preferably a maximum of 55.0 pm, independently of each other, for each side. ThyssenKrupp Steel Europe AG 237082P10WO

[0057] December 4, 2025

[0058] 10 / 17

[0059] Steel sheet generally refers to a hot-rolled or cold-rolled flat steel product, which can be supplied in sheet form, blank form, or strip form. The thickness of the steel sheet can be between 0.30 and 10.0 mm, in particular at least 0.40 mm, preferably at least 0.45 mm and a maximum of 4.0 mm, preferably a maximum of 3.5 mm, or in particular at least 1.0 mm, preferably at least 1.5 mm and a maximum of 9.0 mm, preferably a maximum of 8.0 mm.

[0060] Advantageously, the zinc grains occupy a surface area of, in particular, at least 76, 77, 78, 79%, preferably at least 80, 81, 82, 83, 84%, preferably at least 85, 86, 87, 88, 89%, and especially preferably 90, 91, 92, 93, 94% in the measuring area.

[0061] It is therefore desirable to keep the eutectic area, or rather the area fraction of the eutectic in the ZM coating, low in the SEM image, so that it should not exceed 25% of the measurement area. The area fraction of the eutectic in the measurement area should, in particular, be a maximum of 20%, 19%, 18%, 17%, or 16%; preferably a maximum of 15%, 14%, 13%, 12%, or 11%; and more preferably a maximum of 10%, 9%, 8%, 7%, or 6%. An area fraction of at least 2% is essential.

[0062] According to one embodiment, in a vertical section through the coated steel sheet, at least two adjacent zinc grains, each having a grain size in vertical orientation smaller than the thickness of the zinc coating, are arranged on different levels, in particular one above the other and / or offset from each other, within the zinc coating in the SEM image.

[0063] According to one embodiment, in a vertical section through the coated steel sheet, at least two, preferably at least three, particularly preferably at least four adjacent zinc grains, each having a grain size in vertical orientation smaller than the thickness of the zinc coating, are arranged on different planes, in particular one above the other and / or offset from each other, within the zinc coating in the SEM image.

[0064] Each zinc grain has a grain size and also a determinable center of gravity when viewed in cross-section, so that "on different levels" means that the centers of gravity of the at least two or three adjacent zinc grains are arranged at different locations, at least sectionally, within the zinc coating, preferably at different angles. ThyssenKrupp Steel Europe AG 237082P10WO

[0065] December 4, 2025

[0066] 11 / 17 was positioned relative to the sheet metal surface. This allows for the advantageous control of cracks and / or spalling caused by mechanical stresses, such as during the forming of the coated steel sheet, compared to a zinc grain in a conventional zinc coating, which essentially covers the entire thickness of the zinc coating in one section. This prevents corrosion protection failure. Even if spalling occurs later after forming in the already installed state, corrosion resistance is maintained due to the continued integrity of the zinc coating.

[0067] The steel sheet in question is a steel alloy, preferably a carbon-containing steel alloy.

[0068] The steel sheet is hot-rolled or cold-rolled and comprises an alloy containing or consisting of the following elements in wt.%:

[0069] C: 0.0003 to 0.50%;

[0070] Mn: 0.0005 to 3.0%;

[0071] P: up to 0.15%;

[0072] S: up to 0.050%;

[0073] N: up to 0.10%; optionally one or more of the following elements:

[0074] AI: 0.0050 to 1.60%;

[0075] Si: up to 1.80%;

[0076] Note: up to 0.20%;

[0077] Ti: up to 0.20%;

[0078] V: up to 0.20%;

[0079] B: up to 0.030% and / or

[0080] Cu: up to 0.80% and / or

[0081] Cr: up to 1.0% and / or

[0082] Ni: up to 0.20% and / or

[0083] Mon: up to 0.25% and / or

[0084] Sn: up to 0.10%;

[0085] Ca: up to 0.005%;

[0086] Residual iron and unavoidable impurities. ThyssenKrupp Steel Europe AG 237082P10WO

[0087] December 4, 2025

[0088] 12 / 17

[0089] The steel alloy can preferably be a structural steel according to DIN EN 10025:2020. A structural steel can be unalloyed (see DIN EN 10025-2), normalized (see DIN EN 10025-03), or low-alloy fine-grained structural steel (see DIN EN 10025-4), depending on the intended use. Examples of steels of this type are available under the standard designations S220, S235, S250, S275, S355(N), S420(N), and S460MC.

[0090] Such steels have an alloy that contains or consists of the following elements in wt.%:

[0091] C: 0.030 to 0.250%, in particular 0.040 to 0.250%, preferably 0.050 to 0.250%;

[0092] Si: 0.00 to 0.70%, in particular 0.0010 to 0.40%, preferably 0.0010 to 0.30%;

[0093] Mn: 0.010 to 2.0%, in particular 0.010 to 1.90%, preferably 0.010 to 1.80%;

[0094] P: up to 0.10%, in particular up to 0.080%, preferably up to 0.060%;

[0095] S: up to 0.050%, in particular up to 0.040%, preferably up to 0.030%;

[0096] N: up to 0.10%, in particular up to 0.050%, preferably up to 0.030%;

[0097] AI: 0.010 to 0.150%, in particular 0.010 to 0.10%, preferably 0.010 to 0.090%; optionally one or more of the following elements:

[0098] Cu up to 0.80% and / or Cr up to 0.70% and / or Nb up to 0.10% and / or Ti up to 0.20%;

[0099] Residual iron and impurities resulting from the smelting process.

[0100] Structural steel such as S220GD, S250GD, S280GD, S320GD, S350GD, S390GD, S420GD, S450GD, S550GD is also preferably used as sheet steel, preferably cold-rolled.

[0101] Alternatively, interstitially free steel, see also DIN EN 10346, or soft steel such as DX51D, DX52D, DX53D, DX54D and / or DX56D is used as steel sheet.

[0102] Such steels have an alloy that contains or consists of the following elements in wt.%:

[0103] C: 0.0003 to 1.0%, in particular 0.001 to 0.90%, preferably 0.001 to 0.80%;

[0104] Si: 0.00 to 0.50%, in particular 0.0010 to 0.40%, preferably 0.0010 to 0.30%;

[0105] Mn: 0.0005 to 2.0%, in particular 0.010 to 1.90%, preferably 0.010 to 1.80%;

[0106] P: up to 0.10%, in particular up to 0.080%, preferably 0.0002 to 0.060%;

[0107] S: up to 0.050%, in particular up to 0.040%, preferably 0.0003 to 0.030%;

[0108] N: up to 0.10%, in particular up to 0.080%, preferably 0.0001 to 0.070%; ThyssenKrupp Steel Europe AG 237082P10WO

[0109] December 4, 2025

[0110] 13 / 17

[0111] AI: 0.0010 to 1.0%, in particular 0.0010 to 0.90%, preferably 0.0010 to 0.80%; one or both of the following elements:

[0112] Nb: 0.0001 to 0.20%, in particular 0.0002 to 0.10%, preferably 0.0003 to 0.050%;

[0113] Ti: 0.0005 to 0.20%, in particular 0.010 to 0.150%, preferably 0.010 to 0.120%; optionally one or more of the following elements:

[0114] B up to 0.0050% and / or Cu up to 0.20% and / or Cr up to 0.20% and / or Ni up to 0.20% and / or Mo up to 0.150% and / or Sn up to 0.10%;

[0115] Residual iron and unavoidable impurities.

[0116] In another alternative, micro-alloyed steel such as HX260LAD, HX300LAD, HX340LAD, HX380LAD and / or HX420LAD is used as sheet steel.

[0117] C: 0.010 to 0.40%, in particular 0.015 to 0.30%, preferably 0.020 to 0.20%;

[0118] Si: 0.00 to 0.90%, in particular 0.0010 to 0.80%, preferably 0.0010 to 0.70%;

[0119] Mn: 0.010 to 2.20%, in particular 0.015 to 2.10%, preferably 0.020 to 2.0%;

[0120] P: up to 0.10%, in particular up to 0.080%, preferably 0.0002 to 0.070%;

[0121] S: up to 0.070%, in particular up to 0.060%, preferably 0.0003 to 0.050%;

[0122] N: up to 0.10%, in particular up to 0.090%, preferably 0.0001 to 0.080%;

[0123] AI: 0.0050 to 1.2%, in particular 0.0070 to 1.10%, preferably 0.010 to 1.0%; at least one of the following elements:

[0124] Nb: 0.0001 to 0.25%, in particular 0.005 to 0.20%, preferably 0.010 to 0.150%;

[0125] Ti: 0.001 to 0.40%, in particular 0.005 to 0.30%, preferably 0.010 to 0.20%;

[0126] V: 0.001 to 0.10%, in particular 0.005 to 0.080%, preferably 0.010 to 0.050%; optionally one or more of the following elements:

[0127] B up to 0.0050% and / or Cu up to 0.40% and / or Cr up to 0.70%;

[0128] Residual iron and unavoidable impurities.

[0129] Hot-rolled steels are frequently used as the base substrate.

[0130] Of course, the use of cold-rolled steels, such as S550GD, is also conceivable.

[0131] A corresponding classification of the above-mentioned steels can be found in DIN EN 10027. ThyssenKrupp Steel Europe AG 237082P10WO

[0132] December 4, 2025

[0133] 14 / 17

[0134] Impurities are present in the steel sheet in cumulative amounts up to 0.5 wt.%, in particular up to 0.4 wt.%, preferably up to 0.3 wt.%.

[0135] According to another aspect, the invention relates to a coated sheet steel component with a zinc coating and a coating weight on both sides between 200 and 1000 g / m². 2, which, in addition to zinc and unavoidable impurities, comprises the elements aluminum with a content of 0.5 to 8.0 wt.% and magnesium with a content of 0.5 to 8.0 wt.% in the coating, wherein the zinc-metal coating comprises or consists of zinc grains and eutectic material, having at least one bending edge, wherein cracks and / or spalling are present at the outer bending edge, which only partially extend into the zinc-metal coating and / or occur locally along the bending edge on the zinc-metal coating. The cracks and / or spalling, which, for example, only partially extend into the zinc-metal coating, do not, however, reach the sheet surface. Thus, the cracks, in particular, extend within the eutectic material and terminate in a single zinc grain.

[0136] Preferably, a coated sheet steel component with at least one bending edge, after an OT bending test according to DIN EN ISO 7438 at room temperature, shows no cracks or flaking extending to the sheet surface in the cross-section evaluation (e.g. using a light microscope or SEM), so that no exposure of the steel occurs.

[0137] Due to the presence of the zinc grains, especially the multi-layered arrangement of small zinc grains, the corrosion protection of the zinc coating remains intact despite damage. This ensures the zinc coating's resistance to pressure and deformation.

[0138] Preferably, and according to a further aspect of the invention, the coated steel sheet component is a deformed coated steel sheet with a zinc coating and a coating weight between 200 and 1000 g / m². 2, which, in addition to zinc and unavoidable impurities, comprises the elements aluminum with a content of 0.5 to 8.0 wt.% and magnesium with a content of 0.5 to 8.0 wt.% in the coating, wherein the zinc coating comprises or consists of zinc grains and eutectic material, wherein, in a vertical section through the coated steel sheet in an SEM image, a rectangular measuring area (M) with a long side of 200 pm and a short side of 14 pm is measured within the zinc coating such that the long side of the rectangle is aligned parallel to the sheet plane, wherein the zinc grains occupy an area fraction of at least 75% in the measuring area. ThyssenKrupp Steel Europe AG 237082P10WO

[0139] December 4, 2025

[0140] 15 / 17

[0141] The coated sheet steel component is particularly preferred as a deformed coated sheet steel component in any of the above described versions or combinations thereof.

[0142] In particular, the coated sheet steel component is a deformed coated sheet steel manufactured as described above using the inventive method as described above.

[0143] The at least one bending edge is formed during the forming of a coated steel sheet, which may include roll forming, drawing, or bending. The at least one bending edge extends, for example, substantially throughout the entire sheet, so that the steel sheet component forms a profile, preferably with at least two bending edges, which, for example, run substantially parallel to each other. Thus, the steel sheet component can be a roll profile, a drawn part, or a bent part.

[0144] To avoid repetition, reference is made to the explanations relating to the coated steel sheet according to the invention.

[0145] According to another aspect, the invention relates to the use of the sheet steel component according to the invention as a frame and / or as a support for a solar panel.

[0146] The invention is explained in more detail with reference to the following exemplary embodiments in conjunction with the drawing.

[0147] Using a hot-dip fusion simulator, large-scale hot-dip fusion processes can be replicated on a laboratory scale. For example, a hot-rolled steel sheet of grade S235 with a thickness of 1.5 mm was used in the Iwatani HDPS V hot-dip fusion simulator, with 4 tests performed using different coating weights [in g / m²]. 2Tests were carried out on zinc-metal coatings with varying aluminum (in wt%) and magnesium (in wt%) contents, the remainder being zinc and unavoidable impurities. Stripping was performed in atmospheric air using a nitrogen-air mixture with a volume ratio of 30:70. Different cooling rates rK (in °C / s) were used for stripping, see Table 1. ThyssenKrupp Steel Europe AG 237082P10WQ

[0148] December 4, 2025

[0149] 16 / 17

[0150] Table 1

[0151] Samples were taken from the four experiments and the zinc grains (Z) and eutectic phases (E) were visualized using scanning electron microscopy (SEM), as shown in Figures 1-4. In each SEM image, a rectangular measurement area (M), schematically depicted, with a long side of 200 pm and a short side of 14 pm, was positioned within the zinc coating such that the long side of the rectangle was aligned parallel to the sheet plane. A grid of 10 nm x 10 nm grid elements was used in the image processing software ImageAccess to assist in this process. Figures 1 to 4 show the SEM images in vertical section of the samples described above, wherein samples 1 to 3 (Figures 1-3) were cut from stall sheets (1) according to the invention and sample 4 (Figure 4) was cut from a conventionally manufactured steel sheet.The SEM images were taken using a Tescan Vega instrument. The (primary) zinc grains (Z) are clearly visible in the zinc coating, and (E) represents the eutectic phases or the eutectic, which essentially comprise a combination of zinc and magnesium.

[0152] For quantifying the area fraction of zinc-rich grains (primary grains) and eutectic regions, backscattered electron microscopy (BSE) is preferably used, as it provides a pronounced material contrast. Phase assignment is preferably validated by energy-dispersive X-ray spectroscopy (EDX / EDS). Segmentation of the image data into "Zn-rich" versus "eutectic regions" is preferably performed using thresholding methods based on the BSE grayscale values, which are verified against the EDX distribution images and adjusted if necessary. The results are preferably reported as a mean value with standard deviation from several measurement fields distributed across the layer.

[0153] Furthermore, components with a sheet metal edge were formed from the samples taken, i.e., a process was imitated which occurs during roll forming or drawing or ThyssenKrupp Steel Europe AG 237082P10WO

[0154] December 4, 2025 17 / 17 when bending parts to form sheet steel components which are ideally suited or can be used as scaffolding and / or supports for solar panels, as they can provide very good and sufficient corrosion protection for at least 20 years.

Claims

ThyssenKrupp Steel Europe AG 237082P10WO December 4, 2025 1 / 4 Patent claims 1. Coated steel sheet with a zinc coating and a coating weight on both sides between 200 and 1000 g / m² 2 , which, in addition to zinc and unavoidable impurities, comprises the elements aluminium with a content of 0.5 to 8.0 wt.% and magnesium with a content of 0.5 to 8.0 wt.% in the coating, wherein the ZM coating comprises or consists of zinc grains (Z) and eutectic (E), characterized in that, in a vertical section through the coated steel sheet in an SEM image, a measuring area (M) having a rectangle with a long side of 200 pm and a short side of 14 pm is stretched within the ZM coating such that the long side of the rectangle is aligned parallel to the sheet plane, wherein the zinc grains (Z) occupy an area fraction of at least 75% in the measuring area (M).

2. Steel sheet according to claim 1, wherein the zinc grains (Z) occupy a surface area of ​​at least 85% in the measuring surface (M).

3. Steel sheet according to one of the preceding claims, wherein the eutectic (E) occupies a surface area of ​​a maximum of 15% in the measuring surface (M).

4. Steel sheet according to one of the preceding claims, wherein in a vertical section through the coated steel sheet at least two adjacent zinc grains (Z) are arranged at least partially on different planes (I, II, III), in particular one above the other and / or offset from each other, within the ZM coating.

5. Steel sheet according to one of the preceding claims, wherein at most 5% of the zinc grains extend in a vertical orientation over the entire local thickness of the ZM coating.

6. Steel sheet according to one of the preceding claims, wherein the area fraction of continuous eutectic paths in the SEM measurement area defined in claim 1, measured as the fraction of perpendicular paths passing only through the eutectic, is at most 5%. ThyssenKrupp Steel Europe AG 237082P10WO December 4, 2025 2 / 4 7. Steel sheet according to any of the preceding claims, which is hot-rolled or cold-rolled and contains or consists of an alloy of the following elements in wt.%: C: 0.0003 to 0.50%; Mn: 0.0005 to 3.0%; P: up to 0.15%; S: up to 0.050%; N: up to 0.10%; optionally one or more of the following elements: AI: 0.0050 to 1.60%; Si: up to 1.80%; Note: up to 0.20%; Ti: up to 0.20%; V: up to 0.20%; B: up to 0.030% and / or Cu: up to 0.80% and / or Cr: up to 1.0% and / or Ni: up to 0.20% and / or Mon: up to 0.25% and / or Sn: up to 0.10%; Ca: up to 0.005%; Residual iron and unavoidable impurities.

8. Method for producing a zinc coating on a steel sheet, comprising: - the immersion of an uncoated steel sheet in a zinc molten bath, which, in addition to zinc and unavoidable impurities, includes the elements aluminium with a content of 0.5 to 8.0 wt.% and magnesium with a content of 0.5 to 8.0 wt.%, - the double-sided scraping of the liquid zinc melt by means of a scraping device to adjust a coating weight on both sides from 200 to 1000 g / m² 2 and - the cooling of the coated steel sheet at an average cooling rate of at least 15 °C / s, measured between the exit from the ThyssenKrupp Steel Europe AG 237082P10WO December 4, 2025 3 / 4 ZM melt and the first deflection roller over the strip running distance, whereby the strip surface temperature is measured directly above the melt pool and in front of the first deflection roller.

9. Method according to claim 8, wherein the cooling section between the exit of the coated steel sheet from the ZM melt and the first deflecting roller is divided into three phases, namely: a) a first cooling phase from the melt bath exit to the point at 1 / 3 of the strip travel distance, b) a second cooling phase from the point at 1 / 3 to the point at 2 / 3 of the strip travel distance and c) a third cooling phase from the point at 2 / 3 of the strip travel distance to immediately before the first deflecting roller, wherein the mean cooling rate in the first cooling phase a) is greater than 22 °C / s.

10. Method according to claim 8 or 9, wherein the cooling section between the exit of the coated steel sheet from the zinc melt and the first deflecting roller is divided into three phases, namely: a) a first cooling phase from the melt bath exit to the point at 1 / 3 of the strip travel distance, b) a second cooling phase from the point at 1 / 3 to the point at 2 / 3 of the strip travel distance and c) a third cooling phase from the point at 2 / 3 of the strip travel distance to immediately before the first deflecting roller, wherein the mean cooling rate in the second cooling phase b) is greater than 15 °C / s.

11. Coated sheet steel component with a zinc coating and a coating weight on both sides between 200 and 1000 g / m² 2, which, in addition to zinc and unavoidable impurities, comprises the elements aluminium with a content of 0.5 to 8.0 wt.% and magnesium with a content of 0.5 to 8.0 wt.% in the coating, wherein the zinc coating comprises or consists of zinc grains (Z) and eutectic (E), having at least one bending edge, characterized in that cracks, which only partially extend into the zinc coating, and / or spalling, which occurs locally along the bending edge on the zinc coating, are present at the outer bending edge, wherein the cracks and / or spalling do not extend to the sheet surface.

12. Steel sheet component according to claim 11, wherein the coated steel sheet component is a rolled profile. ThyssenKrupp Steel Europe AG 237082P10WO December 4, 2025 4 / 4 13. Steel sheet component according to claim 11, wherein the coated steel sheet component is a drawn part.

14. Steel sheet component according to claim 11, wherein the coated steel sheet component is a bent part.

15. Use of a coated sheet steel component according to one of claims 11 to 14 as a frame and / or as a support for a solar panel.

Images