WO2019011644A1 - METHOD FOR PRODUCING A PRESS-CURED COMPONENT - Google Patents

Abstract

The present invention relates to a method for producing a steel component comprising a substrate and a coating, a corresponding steel component and its use in the automotive sector.

Description

 Method for producing a press-hardened component

Technical area

The present invention relates to methods for producing a steel component comprising a substrate and a coating, a corresponding steel component and its use in the automotive sector.

Technical background

In order to provide the combination of low weight, maximum strength and protective effect required in modern body construction, today components are used in the areas of the body, which may be particularly high loads in the event of a crash, which are hot-formed from high-strength steels. In hot forming, also called hot press hardening, steel blanks, previously separated from cold or hot rolled steel strip, are heated to a forming temperature generally above the austenitizing temperature of the respective steel and placed in the mold of a forming press in the heated state. In the course of the subsequent transformation, the sheet metal blank or the component formed from it undergoes rapid cooling due to the contact with the cool tool. The cooling rates are set so that a hardness structure results in the component.

WO 2015/036151 A1 discloses a method for producing a steel component provided with a metallic, corrosion-protective coating and a corresponding steel component. The method according to this document comprises coating a flat steel product with an alloy of aluminum, zinc, magnesium and optionally silicon and iron, cutting a blank from the flat steel product, heating the blank and reshaping the blank to obtain the desired steel component.

DE 699 07 816 T2 discloses a method for producing a coated hot and cold rolled steel sheet having very high strength after thermal treatment. For this purpose, a flat steel product is provided with a coating and thermally treated. During thermal treatment, the workpiece is heated to a temperature of over 750 ° C.

The present invention is based on the object to provide a method for the production of steel components comprising a substrate and a coating available, can be obtained with the corresponding steel components, characterized by a particularly high bending angle α according to VDA 238-100 and thus also characterized by an improved crash behavior when used in the automotive sector. NEN. Furthermore, according to the invention, in coated flat steel products, the average arithmetic mean roughness R _{a should} lie within a certain optimum interval, in order thereby to achieve an optimized bending angle, in order to improve the properties of the flat steel products.

miteinander verknüpft sind, umfassend wenigstens die Schritte: This object is achieved by the inventive method for producing a steel component comprising a substrate and a coating, wherein the bending angle a of the steel component (in °) according to VDA238-100 and the arithmetic mean roughness R _a (in μιη) according to DIN EN 10049: 2014- 03 according to the general formula (1)

linked together, comprising at least the steps:

(A) Providing a flat steel product containing (all data in% by weight)

0.15 to 0.50 C,

 0.50 to 3.0 Mn,

 0, 10 to 0.50 Si,

 0.01 to 1.00 Cr,

 up to 0.20 Ti,

 up to 0, 10 AI,

 up to 0, 10 P,

 up to 0, 1 Nb,

 up to 0.01 N,

 up to 0.05 S and

 up to 0, 1 B,

 Balance Fe and unavoidable impurities, containing a coating (all figures in% by weight)

3 to 15 Si,

 1 to 3.5 Fe,

 up to 0.5 alkali and / or alkaline earth metals,

Rest AI and unavoidable impurities, (B) treating the flat steel product at a furnace temperature T ₁ (in K) for a duration ti (in h) such that p _{1 has} a value of 8 to 30 according to the equation of the general formula (2)

(C) forming the heated flat steel product of step (B) in a mold with simultaneous cooling to obtain the steel component.

Furthermore, these objects are also achieved by a corresponding steel component and by the use of the steel component according to the invention in the automotive sector, in particular as bumper support / reinforcement, door reinforcement, B-pillar reinforcement, A-pillar reinforcement, roof frame or sill.

The process according to the invention is described in detail below:

Step (A) of the process according to the invention comprises the provision of a flat steel product containing (all data in% by weight)

0.15 to 0.50, preferably 0.20 to 0.30, particularly preferably 0.21 to 0.25 C,

0.50 to 3.0, preferably 0.80 to 2.00, particularly preferably 1.00 to 1.50 Mn,

0.10 to 0.50, preferably 0.15 to 0.40, particularly preferably 0.20 to 0.30 Si,

0.01 to 1, 00, preferably 0, 10 to 0.5, particularly preferably 0, 10 to 0.40 Cr,

up to 0.20, preferably 0.01 to 0, 10, particularly preferably 0.01 to 0.04, Ti,

up to 0, 10, preferably 0.01 to 0.05, particularly prefers 0.02 to 0.05 AI,

up to 0.10, preferably 0.00 to 0.05, particularly preferably 0.00 to 0.02 P,

up to 0, 1, preferably 0.001 to 0, 1 Nb,

up to 0.01 N,

up to 0.05, preferably 0.00 to 0.005, more preferably 0.00 to 0.003 S and

up to 0.1, preferably 0.001 to 0.05, particularly preferably 0.002 to 0.0035 B,

Balance Fe and unavoidable impurities, containing a coating (all figures in% by weight)

3 to 15 Si,

1 to 3.5 Fe,

up to 0.5 alkali and / or alkaline earth metals, Rest AI and unavoidable impurities.

Unavoidable impurities in the substrate according to the invention are, for example, Cu, Mo, V, Ni and / or Sn.

According to the invention, in step (A) of the process according to the invention, any flat steel product which appears suitable to the person skilled in the art with the corresponding analysis and a corresponding coating can be used. The flat steel product used is preferably a strip, in particular a hot strip or a cold strip, around a sheet, ie. H. a piece of a hot strip or a cold strip, or a board made of a hot strip or a board made of a cold strip. The present invention preferably relates to the method according to the invention, wherein the flat steel product is a board made of a hot strip or a board made of a cold strip.

Methods for producing a hot strip or a cold strip are known per se to those skilled in the art and described for example in Hoffmann, Hartmut; Neugebauer, Reimund; Spur, Günter (2012): Handbuch Umformen. Munich: Carl Hanser Verlag GmbH & Co. KG., Pages 109 to 165 and pages 196 to 207.

The flat steel product according to the invention is provided with a coating, the coating preferably having 3 to 15, particularly preferably 7 to 12, very particularly preferably 9 to 10 Si, 1 to 3.5, preferably 2 to 3.5 Fe, up to 0, 5 alkali and / or alkaline earth metals, for example magnesium, calcium and / or lithium, the radical AI and unavoidable impurities (all figures in wt .-%).

Methods for producing a corresponding coated flat steel product are known per se to those skilled in the art, for example, the coating can be carried out by a fire coating, an electrolytic coating or by means of a piece coating process. The present invention therefore preferably relates to the method according to the invention, wherein the coating takes place by means of a fire coating, an electrolytic coating or by means of a piece coating process.

Preferably, the application of the aluminum-silicon-iron alloy is carried out by means of a continuous fire-coating process.

Preferably, in the coating, the temperature of the aluminum molten bath is between 650 ° C and 720 ° C.

Silicon in the coating acts as a diffusion blocker and serves to calm the melt bath when applying the coating formed from the aluminum alloy by means of fire coating. The thickness of the coating according to the invention is preferably from 5 to 60 μιτι, preferably 10 to 40 μιτι. This results in an inventive overlay weight of the two-sided coating of 30 to 360 g / m ² , preferably 100 to 200 g / m ² , particularly preferably 120 to 180 g / m ² , for example 150 g / m ² . The present invention therefore preferably relates to the process according to the invention, wherein the coating weight of the double-sided coating is from 30 to 360 g / m ² .

According to the invention, the coating may be present on one side of the flat steel product or on both sides of the flat steel product. The present invention therefore preferably relates to the process according to the invention, wherein the coating is present on one side of the flat steel product or on both sides of the flat steel product, in particular on both sides of the flat steel product.

According to the invention, the coated flat steel product from step (A) is preferably transferred directly into the process step (B) according to the invention. However, it is also possible that between the steps (A) and (B) further steps are carried out, for example separation of areas, in particular sheets or blanks of the flat steel product, for example by shearing or laser cutting, introducing holes by laser machining or punching, preceding heat treatments to change the properties of the coating or substrate, and / or to introduce a pre-deformation.

Step (B) of the process according to the invention comprises treating the steel flat product at a furnace temperature Ti (in K) for a duration ti (in h) such that pi in accordance with the equation of the general formula (2) has a value from 8 to 30, preferably from 9 to 30, more preferably 9 to 26, most preferably 10 to 22

It has been found according to the invention that particularly advantageous products, in particular with respect to the bending angle α according to VDA 238-100, are obtained if in step (B) the heat treatment is carried out such that the parameter p1 mentioned in equation (2) has a value of 8 to 30.

In the equation of the general formula (2), Ti means the furnace temperature in Kelvin, ie. the temperature, which is carried out in the oven, in the step (B) of the method according to the invention is present. According to the invention, it is possible to use all ovens known to the person skilled in the art, for example roller hearth furnaces, chamber furnaces, multilayer chamber furnaces, lifting beam furnaces. According to the invention, Ti is preferably from 1070 to 1350 K, particularly preferably from 1100 to 1250 K, wherein it must be satisfied at the same time that pl has a value of from 9 to 30 according to equation (2). The present invention therefore preferably relates to the process according to the invention, Ti being from 1070 to 1350 K, particularly preferably from 1100 to 1250 K.

In the equation of the general formula (2), ti is the duration for which the flat steel product is exposed to the corresponding temperature Ti. This is preferably the period from retraction / insertion of the sample in the oven to the extension / removal of the sample from the oven. According to the invention, ti is given in hours (h), ti according to the invention is preferably 0.02 to 0.50 h, more preferably 0.04 to 0.50 h, wherein it must be satisfied at the same time that pi has a value according to equation (2) from 8 to 30, preferably from 9 to 30, more preferably from 9 to 26, most preferably from 10 to 22 having. The present invention therefore preferably relates to the process according to the invention, where ti is 0.02 to 0.50 h, more preferably 0.04 to 0.50 h.

According to the invention, it is possible for a constant temperature Ti to prevail during step (B) over the entire time ti. It is also possible according to the invention for temperatures Ti to be present within the time ti which are not constant, for example in one part (a) of the period ti (t _la ) there is a temperature Ti _a in a further part (b) of the period ti (t _lb ) is a temperature T _lb , and in a further part (c) of the period ti (t _lc ) is a temperature T _lc, etc., before. In this embodiment, in the equation of the general formula (2), the corresponding period ti (ti = t _la + t _lb + t _lc + ...) and the arithmetic mean of the corresponding associated temperatures, for example, T _la , T _lb , T _lc etc, used for Ti, if the temperature of the oven exceeds 550 ° C.

At values of pi below 9, the arithmetic mean roughness R _{a is} in a range which can negatively influence the further processing properties, for example tribological properties during forming, heat transfer, paintability.

During step (B) of the process according to the invention, in particular the period from the introduction / insertion of the sample into the oven until the sample is extracted / removed from the oven, a desired arithmetic mean roughness value R _{a is achieved} . This can be determined by methods known to those skilled in the art, preferably the arithmetic mean roughness R _{a is determined} according to DIN EN 10049: 2014-03 in μιη, particularly preferably as an average value of 40 measurements for samples coated on both sides, 20 on each side of the samples, each transverse to the rolling direction of the sample. For samples coated on one side, the measurement is made only on the coated side.

In a preferred embodiment of the method according to the invention, in a further method step between step (A) and step (B) to the flat steel product at least one particular Range added or further elaborated, so that the particular area of at least one of the attributes of support weight, sheet thickness, chemical composition, which is different from the flat steel product before this further process step, wherein the equation of the general formula (1) applies only to the areas which were already present in the original flat steel product, whereby preferably different mechanical properties are achieved. In another preferred embodiment of the method according to the invention, in a further process step in step (C) at least one particular area of the flat steel product is further developed so that the particular area experiences other cooling conditions in the tool (eg by local heating of the tool) than in a conventional one Press hardening process (with tools cooled to <100 ° C), wherein the equation of the general formula (1) applies only to the areas produced by the usual press hardening process, whereby preferably different mechanical properties are obtained. These embodiments are known to the person skilled in the art as tailored blanks, for example tailor-welded blanks, tailor-rolled blanks, tailored tempering.

In a particularly preferred embodiment, in the further process step, the flat steel product is reinforced in at least one area by an additionally applied, different or similar flat steel product (for example by joining), than in the unreinforced areas.

Step (C) of the process of the invention comprises forming the heated flat steel product of step (B) in a mold while cooling to obtain the steel component.

In general, in step (C) of the process according to the invention, all processes known to the person skilled in the art can be used for hot forming, for example described in hot forming in automotive engineering - processes, materials, surfaces, Landsberg / Lech: Verl. Moderne Industrie, 2012, Die Bibliothek der Technik.

In step (C) of the process according to the invention, the desired steel component is obtained from the flat steel product from step (B) by forming. Thus, in the steel component, the desired hardness structure, ie. At least 80% martensite, the remainder bainite, ferrite and retained austenite, is formed, the forming takes place with simultaneous cooling. The cooling in step (C) of the process according to the invention is preferably carried out at a rate of 27 to 1000 K / s, preferably 50 to 500 K / s. The present invention therefore preferably relates to the process according to the invention, wherein the cooling in step (C) takes place at a cooling rate of 27 to 1000 K / s. By the method according to the invention, a steel component is obtained, comprising a substrate and a coating, wherein the bending angle α (in °) of the steel component and the arithmetic mean roughness R _a

miteinander verknüpft sind . In der allgemeinen Formel (1) bedeutet α den Biegewinkel gemäß VDA 238- 100, den das erfindungsgemäß hergestellte Stahlbauteil aufweist. (in μηι) according to DIN EN 10049: 2014-03 according to the general formula (1)

linked together. In the general formula (1), α means the bending angle according to VDA 238-100, which the steel component produced according to the invention has.

The bending angle α indicated in equation (1) is determined according to the invention with the longitudinal direction of the sample. Bending axis Transverse to rolling direction. If the bending angle α stated in equation (1) is determined according to the invention with the sample position transverse, that is to say, Bending axis Longitudinally determined to the rolling direction, due to the material anisotropy the determined values are approx. 6.5% lower. Also, for other sample plies (e.g., diagonal), slightly different bending angles may be seen, with the deviations preferably between those of the longitudinal and transverse plies, i. between 0 and 6.5%. The values reflect in their overall tendency the relationship according to equation (1) again. Therefore, the equation (1) according to the invention is preferably for bending angle a, with the longitudinal direction of the sample, ie. Bending axis transverse to the rolling direction.

The crash suitability of a steel component depends essentially on the bending angle α at maximum force measured in the "flake bending test for metallic materials" (see Till Laumann, Qualitative and quantitative assessment of the crashworthiness of high-strength steels, Meisenbach Verlag Bamberg, 2010 ( ISBN 978-3-87525-299-6)). High bending angles stand for a good crash suitability.

In general equation (2), R _{a represents} the arithmetic mean roughness and is expressed in μιη.

Preferably, in the steel component according to the invention, the arithmetic mean roughness R _a according to DIN EN 10049: 2014-03 is 1, 30 to 2.30 μm, preferably 1.50 to 2.22 μm, particularly preferably 1.60 to 2.10 μm and the bending angle α according to VDA 238-100 is 54 to 70 °, preferably 54 to 66 °, particularly preferably 54 to 62 °, wherein the values according to the invention must be linked together so that the equation of the general formula (1) applies.

The present invention also relates to a steel component comprising a substrate (all data in% by weight) 0.15 to 0.50, preferably 0.20 to 0.30, particularly preferably 0.21 to 0.25 C,

0.50 to 3.0, preferably 0.80 to 2.00, particularly preferably 1.00 to 1.50 Mn,

0.10 to 0.50, preferably 0.15 to 0.40, particularly preferably 0.20 to 0.30 Si,

0.01 to 1, 00, preferably 0, 10 to 0.5, particularly preferably 0, 10 to 0.40 Cr,

up to 0.20, preferably 0.01 to 0, 10, particularly preferably 0.01 to 0.04, Ti,

up to 0, 10, preferably 0.01 to 0.05, particularly prefers 0.02 to 0.05 AI,

up to 0.10, preferably 0.00 to 0.05, particularly preferably 0.00 to 0.02 P,

up to 0, 1, preferably 0.001 to 0, 1 Nb,

up to 0.01 N,

up to 0.05, preferably 0.00 to 0.005, more preferably 0.00 to 0.003 S and

up to 0.1, preferably 0.001 to 0.05, particularly preferably 0.002 to 0.0035 B,

Balance Fe and unavoidable impurities, and containing a coating (all figures in% by weight)

3 to 15 Si,

1 to 3.5 Fe,

up to 0.5 alkali and / or alkaline earth metals,

miteinander verknüpft sind . Bevorzugt wird dieses erfindungsgemäße Stahlbauteil durch das erfindungsgemäße Verfahren erhalten. Rest AI and unavoidable impurities, the bending angle a of the steel component (in °) and the arithmetic mean roughness R _a (in μιη) according to DI N EN 10049: 2014-03 according to the general formula (1)

linked together. Preferably, this steel component according to the invention is obtained by the method according to the invention.

In particular, the present invention relates to the steel component according to the invention, wherein it is obtained by forming a corresponding flat steel product, wherein the flat steel product has been treated prior to forming at a furnace temperature T ₁ (in K) for a duration ti (in h) such that p ₁ according to the equation of general formula (2) has a value of 8 to 30, preferably from 9 to 30, particularly preferably from 9 to 26, very particularly preferably from 10 to 22, having

More preferably, the present invention relates to the steel component according to the invention, wherein the coating weight of the double-sided coating 30 to 360 g / m2, preferably 100 to 200 g / m ² , particularly preferably 120 to 180 g / m ² , for example 150 g / m ² ,

With regard to the individual features of the steel component according to the invention and the preferred embodiments, what has been said regarding the method according to the invention applies correspondingly.

The present invention also relates to a steel component containing (all data in% by weight)

0.15 to 0.50 C,

0.50 to 3.0 Mn,

0, 10 to 0.50 Si,

0.01 to 1.00 Cr,

up to 0.20 Ti,

up to 0, 10 AI,

up to 0, 10 P,

up to 0, 1 Nb,

up to 0.01 N,

up to 0.05 S and

up to 0, 1 B,

 Residual Fe and unavoidable impurities as substrate, containing a coating (all data in% by weight)

3 to 15 Si,

1 to 3.5 Fe,

up to 0.5 alkali and / or alkaline earth metals,

Rest AI and unavoidable impurities, wherein it has an arithmetic average roughness R _a according to DI N EN 10049: 2014-03 of 1.30 to 2.30 μιτι after press hardening.

The present invention also relates to the use of a coated steel component according to the invention in the automotive sector, in particular as a bumper support / reinforcement, door reinforcement, B-pillar reinforcement, A-pillar reinforcement, roof frame or sill. With regard to the individual features of the use according to the invention and of the preferred embodiments, what has been said regarding the method according to the invention applies correspondingly.

characters

FIG. 1 shows an exemplary topography measurement in an exaggerated representation to illustrate the surface roughness.

FIG. 2 shows an exemplary illustration (micrograph) of two different topologies on the surface of steel components according to the invention, in which:

(1) investment, which is required to produce the microsection

 (2) Surface profile which can be scanned to measure the rough arithmetic mean

(3) AlSi coating on the surface of the coated flat steel product

Examples

The following embodiments serve to illustrate the invention.

Steel flat products (cold strip) of the analysis mentioned in Table 1 are used in the form of blanks. The cold strip was coated and the boards were cut out. The coating of the flat steel products used by way of example is a so-called AlSi coating which can be adjusted, inter alia, by fire coating, consisting of 9 to 10 wt.% Si, 2 to 3.5 wt.% Iron, balance aluminum consists. The thus obtained and coated flat steel products are heated to a temperature Ti (see table) for a duration ti (see table), then placed in a press mold, where they are hot formed to the steel component and as quickly as possible by contact with a conventional hot forming tool within approx. Cooled for 15 seconds to produce a hardened structure (with a martensite content of at least 80%, balance: bainite (0-20%), retained austenite (0-5%), ferrite (0-5%) in the steel substrate of the flat steel product takes place at the following process parameters: dew point <278, 15 K, transfer time furnace to tool 6 s, closing time of the tool 15 s.

For the experiments oven temperature T oven residence time ti, plate thickness and coating weight are varied and accordingly samples are prepared for the bending test. The measurement is carried out on 5 samples each The arithmetic mean is formed from the 5 samples, the average arithmetic mean R _{a being} calculated in μιτι from 40 measurements, 20 to upper and underside of the samples, each transverse to the direction of rolling of the sample, determined in accordance with DIN EN 10049: 2014-03 (A _c = 2.5 mm, stylus R = 5 μm).

Table 1: Composition of the melt used, all data in wt .-%, balance Fe

Table 2 shows the process parameters and the resulting bending angles. Table 2: Process parameters and obtained bending angles

V9 1233 0, 1667 33,3 1,66 50,3

V9 1233 0, 1667 33.3 1.66 50.3

 V comparative experiment

 Ti oven temperature

tl oven residence time

 Pi scalar production parameter

 a arithmetic mean roughness

α Bending angle according to VDA238-100 (longitudinal sample location, ie bending axis transverse to rolling direction)

Industrial Applicability

 The steel component produced according to the invention has an improved crash behavior and can therefore be used advantageously in the automotive sector.

Claims

claims 1. A method for producing a steel component comprising a substrate and a coating, characterized in that the bending angle a of the steel component and the arithmetic mean rough value R _a according to DIN EN 10049: 2014-03 according to the general formula (1)

linked together, comprising at least the steps: (A) Provision of a flat steel product containing (all data in% by weight) 0.15 to 0.50 C,  0.50 to 3.0 Mn,  0, 10 to 0.50 Si,  0.01 to 1.00 Cr,  up to 0.20 Ti,  up to 0, 10 AI,  up to 0, 10 P,  up to 0, 1 Nb,  up to 0.01 N,  up to 0.05 S and  up to 0, 1 B,  Balance Fe and unavoidable impurities, containing a coating (all figures in% by weight) 3 to 15 Si,  1 to 3.5 Fe,  up to 0.5 alkali and / or alkaline earth metals,  Rest AI and unavoidable impurities, Treating the flat steel product at a furnace temperature T ₁ (in K) for a duration ti (in h) such that p _{1 in} accordance with the equation of the general formula (2) has a value of 8 to 30 has

(C) forming the heated flat steel product of step (B) in a mold with simultaneous cooling to obtain the steel component. A method according to claim 1, characterized in that the flat steel product is a board made of a hot strip or a board made of a cold strip. A method according to claim 1 or 2, characterized in that the coating is carried out by a fire coating, an electrolytic coating or by means of a piece coating process. Method according to one of claims 1 to 3, characterized in that the support weight of the double-sided coating is 30 to 360 g / m ² . Method according to one of claims 1 to 4, characterized in that the cooling in step (C) takes place at a cooling rate of 27 to 1000 K / s. Method according to one of claims 1 to 5, characterized in that Ti is 1070 to 1350 K. Method according to one of claims 1 to 6, characterized in that ti is 0.02 to 0.5 h. Method according to one of claims 1 to 7, characterized in that the coating is present on one side of the flat steel product or on both sides of the flat steel product. Method according to one of claims 1 to 8, characterized in that in a further process step between step (A) and step (B) is added to the flat steel product at least one particular area or further elaborated, so that the particular area of at least one of the attributes support weight , Sheet thickness, chemical composition, which is different from the flat steel product before this further process step, wherein the equation of the general formula (1) applies only to the areas that were already present in the original flat steel product, or in a further process step in step (C), at least one particular region of the flat steel product is further processed so that the particular region undergoes different cooling conditions in the tool than in a conventional press hardening process, the equation of the general formula (1) being valid only for the regions , which were produced by means of conventional press hardening process. 10. The method according to any one of claims 1 to 9, characterized in that the steel flat product in the further process step in at least one area by an additionally applied, different or similar flat steel product (eg by joining) reinforced or made thicker than in the non reinforced areas. 11. Steel component comprising a substrate containing (all data in% by weight) 0.15 to 0.50 C,  0.50 to 3.0 Mn,  0, 10 to 0.50 Si,  0.01 to 1.00 Cr,  up to 0.20 Ti,  up to 0, 10 AI,  up to 0, 10 P,  up to 0, 1 Nb,  up to 0.01 N,  up to 0.05 S and  up to 0, 1 B,  Balance Fe and unavoidable impurities, and containing a coating (all figures in% by weight) 3 to 15 Si,  1 to 3.5 Fe,  up to 0.5 alkali and / or alkaline earth metals, Rest AI and unavoidable impurities, characterized in that the bending angle a of the steel component and the arithmetic mean roughness R _a (in μιτι) according to DIN EN 10049: 2014-03 according to the general formula (1) a a = 14.826 ^■ - + 26.193 (1) are linked together. Steel component according to claim 11, characterized in that it is obtained by forming an ent speaking flat steel product, wherein the flat steel product before Umfor men at a furnace temperature T ₁ (in K) for a long ti (in h) has been treated, so that p according to the equation of the general formula (2) has a value of 8 to 30

13. Steel component according to claim 11 or 12, characterized in that the support weight of the double-sided coating is 30 to 360 g / m ² . 14. Steel component containing (all data in% by weight) 0.15 to 0.50 C,  0.50 to 3.0 Mn,  0, 10 to 0.50 Si,  0.01 to 1.00 Cr,  up to 0.20 Ti,  up to 0, 10 AI,  up to 0, 10 P,  up to 0, 1 Nb,  up to 0.01 N,  up to 0.05 S and  up to 0, 1 B,  Residual Fe and unavoidable impurities as substrate, containing a coating (all data in% by weight)  3 to 15 Si,  1 to 3.5 Fe,  up to 0.5 alkali and / or alkaline earth metals, Rest AI and unavoidable impurities, characterized in that it has an arithmetic mean roughness R _a according to DIN EN 10049: 2014-03 of 1, 30 to 2.30 μιη after press-hardening. Use of a coated steel component according to one of claims 11 to 14, in the automotive sector, in particular as a bumper support / reinforcement, door reinforcement, B-pillar reinforcement, A-pillar reinforcement, roof frame or sill.