Flat steel products with improved zinc coating

Abstract

The present invention relates to a flat steel component (13) comprising a steel substrate (15) having a corrosion-resistant coating (17) on at least one surface of the steel substrate (15). The corrosion-resistant coating (17) comprises continuous microchannels (19) connecting the steel substrate (15) to the ambient atmosphere (21). The present invention also relates to a method for manufacturing such a flat steel component.

Description

Technical Field

[0001] The present invention relates to flat steel products comprising a steel substrate having a corrosion protection coating composed of zinc and inevitable impurities on at least one side thereof.

[0002] The present invention also relates to a process for manufacturing this type of flat steel product.

Background Art

[0003] "Flat steel products" are understood herein as rolled products whose length and width are each substantially greater than their thickness. They include, in particular, steel strips and steel plates or blanks.

[0004] In this specification, unless otherwise explicitly noted, numerical values of the amounts of alloying components are always given in mass%.

[0005] The proportion of a specific component in the structure of the steel substrate of flat steel products is reported in area% unless otherwise indicated.

[0006] The "inevitable impurities" of steel, zinc or other alloys in this specification refer to technically inevitable steel elements that enter the steel during production or cannot be completely removed from the steel, but whose amount is low enough not to affect the properties of the steel or the coating.

[0007] Durable parts of automobiles and trucks, such as the crash structures and chassis of automobile bodies, require galvanized steel sheets having a thickness exceeding 1.5 mm and a tensile strength exceeding 590 MPa (high-strength steel), more specifically exceeding 780 MPa (ultra-high-strength steel). The tensile strength for the purposes of this application is determined in accordance with DIN EN ISO 6892, specimen type 1.

[0008] The importance of such steel is increasing due to the impact of electric vehicles. Battery casing components, for example, must be designed to prevent damage to lithium-ion cells in the event of a collision. Furthermore, high-strength and ultra-high-strength materials are suitable for designing lighter components by reducing sheet thickness. However, as strength increases, the risk of hydrogen-induced brittle fracture increases, even with small amounts of diffusible hydrogen in the material.

[0009] Korean Patent Application Publication No. 20190077200 describes a zinc hot-dip plating method that affects hydrogen permeation. Here, particles with a size of 100 nm to 1000 nm are incorporated into the layer to reduce hydrogen permeation. This method makes it possible to reduce hydrogen uptake by the steel at best. Hydrogen already incorporated during the pretreatment stage (strip cleaning, annealing) can no longer escape.

[0010] U.S. Patent No. 8048285 describes an electrolytic ZnNi layer exhibiting low hydrogen embrittlement. Low hydrogen embrittlement is attributed to the coating's permeability to hydrogen. This permeability is achieved by mixing Ni into the electrolytic Zn layer. However, Ni should not be used due to its harmful effects on health. Welding of ZnNi-coated components generates Ni-containing welding fumes, which are known to have carcinogenic effects.

[0011] European Patent No. 3020842 describes how to reduce hydrogen embrittlement by trapping hydrogen, particularly within the internal oxide layer. [Prior art documents] [Patent Documents]

[0012] [Patent Document 1] Korean Patent Application Publication No. 20190077200 Specification [Patent Document 2] U.S. Patent No. 8048285 [Patent Document 3] European Patent No. 3020842 [Overview of the project] [Problems that the invention aims to solve]

[0013] The object of the present invention is to provide a flat steel product having a corrosion-resistant coating composed of zinc and unavoidable impurities, which reduces hydrogen embrittlement. [Means for solving the problem]

[0014] The object of the present invention is achieved by a flat steel product comprising a steel substrate having a corrosion-preventive coating composed of zinc and unavoidable impurities on at least one side of the steel substrate. This corrosion-preventive coating has continuous microchannels that connect the steel substrate to the ambient atmosphere.

[0015] The effect of microchannels is that, for example, diffusible hydrogen diffused into the steel substrate during the pretreatment process before zinc coating can reappear through the anticorrosive coating and does not remain trapped within the steel substrate.

[0016] Pretreatment is required to enable coating of uncoated flat steel products, which are typically protected from oxidation by anticorrosive oil. More specifically, pretreatment includes degreasing (e.g., alkaline degreasing agents combined with electrolytic degreasing agents) and surface treatment or activation steps (e.g., pickling). In all such steps, diffusible hydrogen can be incorporated by the steel substrate. Conventional zinc coatings prevent the degassing of this hydrogen, leaving it bound in the steel substrate and leading to hydrogen embrittlement. The microchannels according to the present invention, conversely, allow the incorporated hydrogen to be degassed.

[0017] In one preferred modified embodiment, the microchannel density is 1 mm -1 (i.e., 1 channel per 1 mm) over 10 mm -1 (i.e., 1 channel per 100 μm), preferably 50 mm -1 (That is, more than 1 channel per 20 μm), more specifically 100 mm-1 (i.e., more than 1 channel per 10 μm). The microchannel density is determined by the vertical metal polished cross section of the flat steel product. Image recognition is used to determine the number of continuous microchannels in a representative portion of the polished cross section. The density is determined as the number per unit length of the polished cross section (in the direction of extension of the flat steel product). Since hydrogen in the steel substrate has relatively free mobility, low-density microchannels are already sufficient to enable hydrogen degassing. As the microchannel density increases, the blocking effect of the anticorrosion coating on hydrogen diffusion decreases. This is advantageous because it facilitates the degassing process.

[0018] In one specific development, the microchannels extend substantially perpendicular to the surface of the steel substrate. This means that for the purposes of this application, more than 90% of all microchannels have a profile such that, in a vertically polished cross section, more than 70% of the length of each microchannel is at an angle of 75° to 105° with respect to the surface of the steel substrate.

[0019] The advantage of this microchannel contour is that the microchannel extends relatively directly, i.e., through a short path, from the steel substrate through the anticorrosion coating to the ambient atmosphere. This ensures rapid diffusion of hydrogen through the microchannel.

[0020] In one specific development form, the microchannels have an angular distribution with a full width at half maximum exceeding 30°, more specifically exceeding 35°, preferably exceeding 40°. The full width at half maximum of the angular distribution of the microchannels is determined by first determining the inclination angle for at least 100 adjacent microchannels in the polished cross-section using image recognition. For this purpose, the center point of the end close to the substrate of each microchannel is identified and connected to the center point of the end far from the substrate of each microchannel. The angle of this connecting line with respect to the substrate surface is specified as the inclination angle of this microchannel. Thus, in the case of a microchannel that is exactly perpendicular, the inclination angle is 90°. The full width at half maximum (FWHM) is determined using statistical evaluation from the frequency distribution of the inclination angles of at least 100 adjacent microchannels. A full width at half maximum exceeding 30° means that the microchannels do not all extend parallel to each other, but instead are distributed substantially over a range of 75° to 105°.

[0021] This angular distribution has several advantages. First, the inclined microchannels are longer compared to vertical microchannels, so the corrosive medium cannot penetrate the substrate. Therefore, the corrosion resistance is better. Second, this type of structure with various inclination angles can withstand relatively high loads during molding. During formation, in comparison, a uniform arrangement with parallel microchannels is more prone to cracking of the coating.

[0022] The flat steel products are developed such that the anticorrosion coating has a thickness d of 1 to 20 μm. The thickness is preferably 5 μm or more. Irrespective of this, the thickness is more specifically 10 μm or less. More preferably, the thickness is 5 to 10 μm. A coating less than 1 μm typically does not provide sufficient protection against corrosion. In typical automotive parts made from flat steel products, sufficient corrosion protection until the end of the product life is achieved with a coating thickness of 5 μm or more. Up to a thickness of 20 μm, the corrosion resistance is improved. Beyond this thickness, there is no more significant improvement. Furthermore, an overly thick coating (exceeding 20 μm) is not preferred because the coating time becomes correspondingly longer and the material cost becomes higher.

[0023] In one specific development form of the flat steel products, the anticorrosion coating has a blocking effect S of 90% or less, preferably 80% or less, against hydrogen permeation.

[0024] The blocking effect of hydrogen permeation is measured by a Devanathan / Stachursky permeation cell using the DIN EN ISO 17081 standard. In this configuration, a sample coated with zinc on one side is clamped between two half-cells, where one cell functions as the H loading cell and the other functions as the measurement cell. The uncoated surface of the sample is coated with palladium. Then, the sample is placed in the permeation cell such that the zinc-plated surface faces the H loading cell. A 0.2 m NaCl solution acts as the electrolyte. 20 mg / l of thiourea is mixed into the test solution as a recombination inhibitor. An H loading cathodic current density of 10 mA / cm 2 and a test temperature of 50 °C are selected. In this configuration, the loading current I Zn is measured. For comparison, the same measurement of the loading current I0 is performed using the same dezincified sample. The blocking effect is defined as follows.

[0025]

Equation

[0026] For forming a ratio relative to the reference sample, the measured values ​​for the blocking effect are independent of the sample's geometric shape (sample size and thickness) and the thickness of the palladium coating.

[0027] The advantage of a lower blocking effect is that hydrogen absorbed by the substrate can effectively escape into the surrounding atmosphere through the anticorrosive coating.

[0028] In one preferred modified embodiment, the anticorrosion coating has a hydrogen permeation time of less than 500 seconds, preferably less than 150 seconds. The hydrogen permeation time is the time that further elapses until hydrogen produced in the Devanathan / Stachursky permeation cell is detected for zinc-coated flat steel products compared to uncoated products.

[0029] The steel base material for flat steel products is, more specifically, high-strength, preferably ultra-high-strength steel. This means that the tensile strength is greater than 590 MPa, more specifically greater than 780 MPa. Particularly preferable is a tensile strength of greater than 1000 MPa, more specifically greater than 1200 MPa. The higher the tensile strength of the base material, the more relevant the coating of the present invention is, as the increase in tensile strength is accompanied by an increase in susceptibility to hydrogen embrittlement, and therefore to brittle fracture.

[0030] Steel substrates are formed from polyphase steels, particularly composite phase steels (CP), duplex steels (DP), or martensitic phase steels (MS). Composite phase steels have a structure composed of a very large proportion of bainite. CP steels have high tensile strength, but their relatively low deformability hinders the design of parts with complex shapes. Duplex steels have a structure composed of a combination of hard structural components (e.g., martensite and / or bainite) and soft structural components (e.g., ferrite). DP steels are suitable for complex parts due to their combination of high strength and good deformability.

[0031] According to one preferred modified embodiment, the steel substrate is composed of a multiphase steel having the following analytical results (values ​​in wt%).

[0032] C: 0.06~0.25 wt% Si: 0.01~2.00 wt% Mn: 1.00~3.00 wt% One or more of the following elements: P: maximum 0.05wt% S: Maximum 0.01wt% Al: max. 1.00wt% Cr: max. 1.00wt% Cu: max. 0.20wt% Mo: maximum 0.30wt% N: Maximum 0.01wt% Ni: max. 0.30wt% Nb: max. 0.08wt% Ti: maximum 0.25wt% V: max. 0.15wt% B: Maximum 0.005wt% Sn: max. 0.05wt% Ca: max. 0.01wt%

[0033] The remainder consists of iron and unavoidable impurities.

[0034] The steel base material is, more specifically, a cold-rolled polyphase steel having the following analysis results (values ​​in wt%). C: 0.06~0.25 wt% Si: 0.10~2.00 wt% Mn: 1.50~3.00 wt% One or more of the following elements: P: maximum 0.05wt% S: Maximum 0.01wt% Al: max. 1.00wt% Cr: max. 1.00wt% Cu: max. 0.20wt% Mo: maximum 0.30wt% N: Maximum 0.01wt% Ni: max. 0.20wt% Nb: max. 0.06wt% Ti: max. 0.20wt% V: maximum 0.10wt% B: Maximum 0.005wt% Sn: max. 0.05wt% Ca: max. 0.01wt%

[0035] The remainder consists of iron and unavoidable impurities.

[0036] In an alternative modification, the steel base material is, more specifically, a hot-rolled polyphase steel having the following analytical results (values ​​in wt%).

[0037] C: 0.06~0.25 wt% Si: 0.01~2.00 wt% Mn: 1.00~3.00 wt% One or more of the following elements: P: maximum 0.05wt% S: Maximum 0.005wt% Al: max. 1.00wt% Cr: max. 1.00wt% Cu: max. 0.20wt% Mo: maximum 0.30wt% N: Maximum 0.01wt% Ni: max. 0.25wt% Nb: max. 0.08wt% Ti: maximum 0.25wt% V: max. 0.15wt% B: Maximum 0.005wt% Sn: max. 0.05wt% Ca: max. 0.01wt%

[0038] The remainder consists of iron and unavoidable impurities.

[0039] In one preferred modified embodiment, the anticorrosion coating is applied by physical vapor deposition (PVD). For this purpose, the coating material, which initially exists in solid or liquid form, is typically vaporized by a physical process. This can be achieved thermally, for example, by directly heating the coating material (e.g., via an electric arc), by irradiating it with a beam of electrons or ions, or by irradiating it with a laser beam. The process for PVD coating is carried out in a coating chamber under low atmospheric pressure so that vapor particles of the vaporized coating material can reach the workpiece to be coated and are not lost in the coating by collision with gas particles in the ambient atmosphere.

[0040] This coating process has several advantages. Firstly, a known characteristic of such processes is that they essentially introduce little to no hydrogen into the starting substrate. Secondly, there is no need to overheat the steel substrate. In the case of hot-dip galvanizing, for example, the steel substrate is inevitably heated to a temperature exceeding 460°C (zinc bath temperature). However, at these temperatures, the hard components of the substrate structure, more specifically martensite, are annealed, thereby causing the steel substrate to lose its properties. This is particularly relevant in the case of DP steel as the steel substrate. Overall, the tests have shown that all of the above steel substrates with sufficiently high tensile strength can be coated by vapor deposition without defects.

[0041] The object of the present invention is also achieved by a process for manufacturing the flat steel products described above. This process is

[0042] The steps of manufacturing or providing a steel substrate, Optionally, a step of degreasing the steel substrate, The optional step of pickling the steel substrate with acid, The steps include applying a corrosion-preventive coating, consisting of zinc and unavoidable impurities, to a steel substrate by physical vapor deposition, and

[0043] The anticorrosion coating includes a thickness d, and the ratio of the thickness d of the anticorrosion coating to the coating speed r during application of the anticorrosion coating is less than 1000 seconds, preferably less than 800 seconds.

[0044] In other words,

[0045]

number

[0046] Preferably

[0047]

number

[0048] Studies have shown that when this ratio is particularly small, a low blocking effect on hydrogen permeation can be obtained.

[0049] In certain particularly preferred embodiments, ratio

[0050]

number

[0051] The processing time is less than 10 seconds, more specifically less than 5 seconds, preferably less than 2.0 seconds, more specifically less than 1.5 seconds, and very preferably less than 1.0 second. Therefore, it is possible to apply a corrosion-preventive coating in a short time that has a considerable thickness (preferably 5-10 μm thick) but nevertheless has a very low blocking effect against hydrogen permeation. Thus, this process is very suitable for continuous coating of long steel strips.

[0052] In particular, this process is developed so that the temperature of the steel substrate during the application of the anticorrosive coating exceeds 50°C, preferably 100°C, very preferably 150°C, and more specifically, 200°C. This preconditioning has proven advantageous in achieving sufficient coating adhesion. In connection with this, a ball impact test according to SEP1931 was used to determine whether the coating adhesion was sufficient. If the coating peeled off during the ball impact test, the coating adhesion was classified as "poor (unacceptable)". If there was no peeling, the coating adhesion was classified as "good (acceptable)".

[0053] According to one preferred embodiment, a corrosion-preventive coating composed of zinc and unavoidable impurities is provided to be applied to a steel substrate by physical vapor deposition by placing the steel substrate in a coating chamber, and the pressure in the coating chamber is regulated. Here, the zinc as the coating material is introduced into the coating chamber at an inflow point while being regulated to a certain temperature.

[0054] According to one preferred embodiment of the present invention, the pressure and temperature are adjusted so that the temperature exceeds the dew point of the coating material. At temperatures above the dew point of the coating material, the coating material exists in its gaseous phase. Adjusting the pressure, for example by increasing it, causes the dew point to shift toward higher temperatures, in this example. The corresponding subsequent adjustment of the temperature ensures that the coating material exists in gaseous form.

[0055] A more preferred embodiment of the present invention provides that the pressure is adjusted to 1 mbar to 100 mbar, preferably 10 mbar to 100 mbar. This ensures that little coating material is lost in the coating due to particle scattering within the coating chamber. At the same time, the pressure is within a range that can be achieved in the process of commercial application in industrial plants, such as in the case of coating steel strips.

[0056] A more preferred embodiment of the present invention provides that, in addition to the coating material, an inert gas is introduced into the coating chamber at an additional inlet point, and the selected pressure is a total pressure consisting of the partial pressure of the coating material and the partial pressure of the inert gas, and the partial pressures of the coating material and the partial pressure of the inert gas are adjusted to adjust the pressure. If the partial pressure of the coating material is not sufficient for a slip flow or continuous flow, it is possible to increase the total pressure via the inert gas to a degree that a slip flow or continuous flow exists. It is conceivable that the additional inlet point be removed from the inlet point. However, it is also conceivable that the coating material be introduced into the coating chamber as a mixture with the inert gas.

[0057] The following table is intended to show some examples of pressure and temperature combinations. The calculated dew points in the table are for zinc as a coating material.

[0058] [Table 1]

[0059] A more preferred embodiment of the present invention provides that nitrogen and / or argon are used as inert gases. Nitrogen and argon are very suitable as inert gases. Both gases do not adversely affect the PVD coating and are also suitable for purging the coating chamber.

[0060] A more preferred embodiment of the present invention provides that, in order to prevent the coating material from cooling, the inert gas is preheated, more specifically, before the point of inflow.

[0061] The present invention will be described in more detail with reference to the drawings. [Brief explanation of the drawing]

[0062] [Figure 1] This is a schematic diagram of a flat steel product with a corrosion-resistant coating. [Figure 2]This is an image of the polished cross-section of a flat steel product with an anti-corrosion coating. [Figure 3] This is a schematic diagram of a microchannel. [Figure 4] This is a schematic diagram of a microchannel. [Figure 5] This figure shows the angular distribution of microchannels. [Modes for carrying out the invention]

[0063] Figure 1 shows a schematic diagram of a flat steel product 13. The flat steel product 13 comprises a steel base material 15 and a corrosion-resistant coating 17 on one side of the steel base material 15. The corrosion-resistant coating 17 is composed of zinc and unavoidable impurities. The corrosion-resistant coating 17 has continuous microchannels 19 that connect the steel base material 15 to the ambient atmosphere 21. (For clarity, only the rightmost of the 18 microchannels shown is labeled with a reference numeral.)

[0064] Figure 2 shows a vertically polished cross-section of the flat steel product 13. This is an exemplary embodiment of number 10 in Table 1, which is described below. The flat steel product 13 includes a steel base material 15 made of cold-rolled multiphase steel having the analysis result A shown below.

[0065] C: 0.11 wt% Si: 0.43 wt% Mn: 2.44 wt% One or more of the following elements: P: 0.01 wt% S: 0.002 wt% Al: 0.03 wt% Cr: 0.62 wt% Cu: 0.05 wt% Mo: 0.07 wt% N: 0.004 wt% Ni: 0.05 wt% Nb: 0.038 wt% Ti: 0.022 wt% V: 0.007 wt% B: 0.0013 wt% Sn: 0.02 wt% Ca: 0.002 wt%

[0066] The remainder consists of iron and unavoidable impurities.

[0067] The flat steel product 13 further comprises a corrosion-resistant coating 17 on one side of the steel substrate 15. The corrosion-resistant coating 17 has a thickness d of 9 μm and is composed of zinc and unavoidable impurities. The corrosion-resistant coating 17 has continuous microchannels 19 that connect the steel substrate 15 to the ambient atmosphere 21. (For clarity, only one of the microchannels is referenced here as well.) In detail in the image shown, there are approximately 27 microchannels, corresponding to a density of 29 channels per 100 μm or 290 mm⁻¹.

[0068] The following table shows several exemplary embodiments and the process parameters associated with their manufacture. Furthermore, the coating adhesion for all samples was determined by the SEP1931 ball impact test. If peeling of the coating occurred during the ball impact test, the coating adhesion was classified as "poor (unacceptable)". If no peeling occurred, the coating adhesion was classified as "good (acceptable)".

[0069] In all exemplary embodiments, the substrate used was a steel blank having a thickness of 1.8 mm. This steel blank was composed of steel having the analytical results shown with reference to Figure 2.

[0070] Example 1 is a reference sample used to determine the blocking effect S. Samples 1-10 were coated by vapor deposition (PVD). In Examples 2-8, an electron beam evaporator was used to melt and evaporate the zinc coating material. In exemplary embodiments 9 and 10, the zinc coating material was melted and evaporated by an electric arc. Examples 2-5 were coated at a substrate temperature of room temperature (i.e., below 50°C). In these cases, anticorrosion coatings with different thicknesses from 0.5 μm to 12 μm were produced. In all four cases, the coating adhesion was insufficient. In Examples 6-8, the substrates were pre-conditioned to a temperature of 200°C. At a coating rate of 8 nm / s, coating thicknesses of 1-8 μm were produced. Samples 6 and 7 exhibit good hydrogen permeability as well as good coating adhesion. In Samples 9 and 10, the substrates were pre-conditioned to a temperature of 240°C. Coating thicknesses of 6.5 μm and 9 μm were achieved at remarkably high coating rates of 7000 nm / s and 10000 nm / s, respectively. Samples 9 and 10 exhibited not only good coating adhesion but also good hydrogen permeability. For comparison, samples 11 and 12 were electroplated with zinc. Sample 12 was also post-treated by heat treatment by holding it at 200°C for 60 minutes in a protective gas atmosphere. In all cases, the resulting blocking effect S was extremely high, causing the introduced hydrogen to remain in the substrate. Therefore, these samples are susceptible to hydrogen embrittlement.

[0071] [Table 2]

[0072] Figure 3 shows schematic details of the microchannels 19 within the anticorrosion coating 17. The microchannels 19 connect the steel substrate 15 to the ambient atmosphere. The microchannels 19 extend substantially perpendicular to the surface 23 of the steel substrate 15. The bottom third of the shown microchannels 19 extends at an angle of 110° to the surface 23 of the steel substrate 15. This is indicated by the angle 25 between the surface 23 of the steel substrate 15 and the tangent 27. The tangent 27 conforms to the contour of the bottom third of the microchannels 19. Further along the contour, the microchannels curve to the right, initially extending almost perpendicularly, then at an angle of approximately 70° to the surface 23 of the steel substrate 15, after which the microchannels 19 expand funnel-like to the surface of the anticorrosion coating. The contour in the region of funnel-shaped expansion is similarly almost perpendicular to the surface 23 of the steel substrate 15. Similar to the bottom third, each angle is determined by fitting a tangent and determining the angle of the tangent to the surface 23. For clarity, only the tangent 27 that fits the contour of the bottom third is shown.

[0073] Figure 4 shows schematic details of the microchannels 19 within the anticorrosion coating 17. The microchannels 19 connect the steel substrate 15 to the ambient atmosphere. The microchannels 19 have an inclination angle 31. The inclination angle 31 is determined by identifying the center point of the end of the microchannel 19 closer to the substrate and connecting it to the center point of the end of the microchannel 19 further from the substrate. The angle of this connecting line 19 with respect to the substrate surface 23 is called the inclination angle 31 of the microchannel 19.

[0074] Figure 5 shows the angular distribution of microchannels in the form of a histogram of tilt angles. The number of tilt angles determined within each range is plotted. The selected step width was 5°. A total of 930 microchannels were evaluated. The full width at half maximum was 42°.

Claims

1. A flat steel product (13) comprising a steel substrate (15) having a corrosion-resistant coating (17) composed of zinc and unavoidable impurities on at least one side of the steel substrate (15), wherein the corrosion-resistant coating (17) has continuous microchannels (19) that connect the steel substrate (15) to the ambient atmosphere (21), and the microchannels (19) are 50 mm －１ A flat steel product characterized by having ultra-high density and having an angular distribution in which the microchannel (19) has a full width at half maximum exceeding 30°.

2. The flat steel product (13) according to claim 1, characterized in that the microchannel (19) extends substantially perpendicular to the surface (19) of the steel substrate (15).

3. The flat steel product (13) according to claim 1 or 2, characterized in that the anticorrosion coating (17) has a thickness d of either 1 to 10 μm or 5 to 10 μm.

4. The flat steel product (13) according to any one of claims 1 to 3, characterized in that the anticorrosion coating (17) has a blocking effect of 90% or less and 80% or less against hydrogen permeation.

5. The flat steel product (13) according to any one of claims 1 to 4, characterized in that the anticorrosion coating (17) has a hydrogen permeation time of less than 500 seconds and less than 150 seconds.

6. The flat steel product (13) according to any one of claims 1 to 5, characterized in that the corrosion-resistant coating (17) is applied by physical vapor deposition.

7. The flat steel product (13) according to any one of claims 1 to 6, characterized in that the steel base material (15) has a tensile strength of more than 590 MPa, more than 1000 MPa, and more than 1200 MPa.

8. The flat steel product (13) according to any one of claims 1 to 7, characterized in that the steel base material (15) is a multiphase steel and a cold-rolled or hot-rolled multiphase steel.

9. The steps of manufacturing or providing a steel base material (15), A step of selectively removing oil, The step of selectively pickling with acid, The steps include applying a corrosion-preventive coating, consisting of zinc and unavoidable impurities, to the steel substrate (15) by physical vapor deposition, and Includes, A process for manufacturing a flat steel product (13) according to any one of claims 1 to 8, wherein the anticorrosion coating (17) has a thickness d, the ratio of the thickness d of the anticorrosion coating to the coating speed r during application of the anticorrosion coating is less than 1000 seconds and less than 800 seconds, and the pressure and temperature are adjusted such that the temperature is above the dew point of the coating material and the pressure is between 10 mbar and 100 mbar.

10. The process according to claim 9, characterized in that the temperature of the steel substrate (15) at the time of application of the anticorrosion coating is one of 50°C, 100°C, or 150°C.

11. The process according to any one of claims 9 to 10, characterized in that the anticorrosion coating, comprising zinc and unavoidable impurities, is applied to the steel substrate (15) by physical vapor deposition by placing the steel substrate (15) in a coating chamber, the pressure in the coating chamber is adjusted, zinc as a coating material flows into the coating chamber at an inflow point, and the zinc is adjusted to a certain temperature.

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