Component comprising a steel substrate, an intermediate layer and an anti-corrosion protective coating, corresponding hardened component, and corresponding method and use

文档序号：1803746 发布日期：2021-11-05 浏览：25次中文

阅读说明：本技术 包括钢基板、中间层和防腐蚀保护涂层的部件、相应硬化部件及相应方法和用途 (Component comprising a steel substrate, an intermediate layer and an anti-corrosion protective coating, corresponding hardened component, and corresponding method and use ) 是由塞巴斯蒂安·施蒂勒斯特凡·比恩霍尔茨于 2020-03-17 设计创作，主要内容包括：本发明涉及一种部件,其包括组织结构可转变成马氏体组织结构的钢基板(3)、覆盖该钢基板且主要成分为钛的金属中间层(2)和覆盖该中间层(2)的防腐蚀保护涂层(1),其中该防腐蚀保护涂层(1)包括一层或多层,并且防腐蚀保护涂层(1)的一个层或其至少与金属中间层(2)邻接的层是金属的并且与该中间层(2)的材料不同。(The invention relates to a component comprising a steel substrate (3) whose microstructure can be transformed into a martensitic microstructure, a metallic intermediate layer (2) covering the steel substrate and comprising titanium as a main component, and an anticorrosion protective coating (1) covering the intermediate layer (2), wherein the anticorrosion protective coating (1) comprises one or more layers, and one layer of the anticorrosion protective coating (1) or at least a layer thereof adjacent to the metallic intermediate layer (2) is metallic and is of a different material than the intermediate layer (2).)

1. A component comprising

-a steel substrate (3) having a microstructure capable of transforming into a martensitic microstructure,

-a metallic intermediate layer (2) covering the steel substrate, the main component of which is titanium

And

-an anti-corrosion protective coating (1) covering the intermediate layer (2),

wherein the corrosion protection coating (1) comprises one or more layers and one layer of the corrosion protection coating (1) or at least a layer thereof adjoining the metallic intermediate layer (2) is metallic and of a different material than the intermediate layer (2).

2. The component of claim 1, wherein

The main component of the metal atoms of the corrosion protection coating (1) or of the metal layer of the corrosion protection coating (1) adjacent to the metal intermediate layer (2) is selected from zinc and manganese

And/or

The metallic zinc and/or the metallic manganese are contained in one of the metal layers of the corrosion protection coating (1) or at least in the metal layer thereof adjacent to the intermediate metal layer (2).

3. Component according to any one of the preceding claims, wherein at least 90%, preferably at least 95%, of the area of the corrosion protection coating (1) facing the steel substrate (3), more preferably the entire surface facing the steel substrate (3), is separated from the steel substrate (3) by the metallic intermediate layer (2).

4. The component of any one of the preceding claims,

(i) wherein the proportion of titanium in the metallic intermediate layer (2) covering the steel substrate (3) is greater than or equal to 90% by weight, based on the total mass of the intermediate layer (2).

And/or

(ii) Material of a metal intermediate layer (2) in which the steel substrate is covered and the main component of which is titanium

Having a melting point of more than 1000 ℃, preferably more than 1200 ℃, preferably more than 1400 ℃, particularly preferably more than 1600 ℃,

and/or

-has a boiling point below 4700 ℃, preferably below 3500 ℃,

and/or

(iii) Wherein

-the intermediate layer (2) of metal whose main component is titanium has a thickness of at most 500nm, preferably of at most 400nm, particularly preferably of at most 300nm,

and/or

The metal intermediate layer (2) whose main component is titanium has a thickness of at least 100nm, preferably at least 150 nm.

5. A component according to any preceding claim, wherein

(i) Metallic zinc is present in one of the metal layers of the corrosion protection coating (1) or at least in the metal layer thereof adjacent to the intermediate metal layer (2), and

the proportion of metallic zinc in the corrosion protection coating (1) covering the intermediate layer is greater than or equal to 55 wt.%, preferably greater than or equal to 96 wt.%, based on the total mass of the corrosion protection coating,

and/or

-the melting point of the corrosion protection coating or of one of the metal layers of the corrosion protection coating (1) or at least of the metal layers adjacent to the metal intermediate layer (2) is greater than or equal to up to 419 ℃, preferably in the range from 419 to 580 ℃ or in the range above 600 ℃,

(ii) The melting point of the corrosion protection coating or of one of the metal layers of the corrosion protection coating (1) or of at least the metal layer adjacent to the intermediate metal layer (2) is greater than or equal to 880 ℃.

6. A hardened part comprising

-a steel substrate (6) and

-an anti-corrosion protective coating (4) protecting the steel substrate, wherein the anti-corrosion protective coating comprises titanium, preferably metallic titanium.

7. The hardened component of claim 6, wherein said hardened component

Obtainable by hardening a component according to any one of aspects 1 to 5

And/or

Is a thermoformed hardened part.

8. Hardened part according to any one of claims 6 to 7, wherein the steel substrate (6) is alloyed with titanium, preferably with titanium and at least one metal selected from zinc and manganese, in the region facing the anti-corrosion protective coating (4),

and/or

Wherein the steel substrate (6) and the corrosion protection coating (4) are connected by a transition zone (5)

-in which iron, titanium and the metallic main constituent of the corrosion protection coating are present, wherein the metallic main constituent changes in the direction of the corrosion protection coating starting from the region of the transition zone close to the steel substrate, from iron to the metallic main constituent of the corrosion protection coating, wherein the main constituent of the corrosion protection coating is preferably selected from zinc and manganese,

and/or

-wherein the mass proportion of iron determined by GDOES decreases from the first mass proportion to half or less than half the first mass proportion in the direction of the corrosion protection coating (4) over a distance of at most 10 μm, preferably 5 μm, starting from the region of the transition zone (5) close to the steel substrate (6), wherein the first mass proportion of iron in the region of the transition zone (5) close to the steel substrate (6) is preferably at least 80 wt.%.

9. Hardened part according to any one of claims 6 to 8,

-wherein the proportion of iron, measured from the outer surface of the corrosion protection coating, in the corrosion protection coating (4) is less than 25 wt.%, preferably less than 20 wt.%, measured in depth of 2 μm, preferably in the range of 1-3 μm, determined by GDOES

And/or

-wherein the maximum value of the titanium mass fraction determined by GDOES is present in the mass fraction-depth map at a depth > 0 μm, preferably in the range of 2 to 20 μm, measured from the outer surface of the corrosion protection coating (4).

10. Method for producing a component, preferably according to any of claims 1 to 5, comprising the steps of:

-producing or providing a steel substrate (3), wherein the microstructure of the steel substrate is capable of transforming into a martensitic microstructure,

-applying (i) titanium or (ii) titanium and one or more other metals onto a steel substrate to form a metallic intermediate layer (2) covering the steel substrate and having titanium as its main component,

-applying one or more metals onto the metallic intermediate layer to form an anti-corrosion protective coating (1) covering the intermediate layer.

11. The method of claim 10, wherein the first and second light sources are selected from the group consisting of,

wherein (i) titanium or (ii) titanium and one or more further metals are applied to the steel substrate (3) and one or more further metals are applied to the intermediate metal layer (2) in such a way that at least 90%, preferably up to 95%, particularly preferably the entire surface of the corrosion protection coating (1) facing the steel substrate is separated from the steel substrate (3) by the intermediate metal layer (2),

and/or

-wherein the proportion of titanium is selected when applying (i) titanium or (ii) titanium and one or more other metals into the steel substrate (3) so that the proportion of titanium in the resulting metallic intermediate layer (2) covering the steel substrate (3) is greater than or equal to 90% by weight, based on the total mass of the intermediate layer (2),

and/or

-the metal intermediate layer (2) in which titanium is the main component obtained has a thickness of at most 500nm, preferably of at most 400nm, particularly preferably of at most 300nm,

and/or

-wherein the resulting intermediate layer (2) of metal, the main component of which is titanium, has a thickness of at least 100nm, preferably at least 150 nm.

12. The method according to any one of claims 10 to 11,

wherein

-applying (i) titanium or (ii) titanium and one or more other metals onto a steel substrate, so as to obtain a metallic intermediate layer (2) covering the steel substrate, the main constituent of which is titanium

And/or

-applying one or more other metals to the intermediate layer of metals, so as to obtain an anticorrosion protective coating (1) covering the intermediate layer,

the above application is carried out by physical vapour deposition,

preferably under the following conditions

At an oxygen partial pressure of less than 0.1mbar, preferably less than 0.01mbar, particularly preferably less than 0.001mbar,

and/or

In the gas phase, the proportion by volume of oxygen is less than 20% by volume, preferably less than 10% by volume, particularly preferably less than 1% by volume.

13. Method for producing a hardened part, preferably according to any one of claims 6 to 9, comprising the steps of:

-providing a component according to any one of claims 1 to 5 or producing a component by a method according to any one of claims 10 to 12,

-treating the provided or produced component to obtain a hardened component.

14. The method according to claim 13, wherein the provided or produced component comprises a steel as steel substrate (3) having a microstructure that is convertible to a martensitic microstructure, preferably a steel having a ferritic-pearlitic microstructure, particularly preferably a manganese-boron steel having a ferritic-pearlitic microstructure, and the treatment comprises:

a heat hardening treatment to transform the microstructure into a martensitic microstructure, and preferably comprises a mechanical treatment, preferably mechanical forming,

wherein said treatment preferably comprises at least the following steps:

(i) heat treatment, wherein the microstructure of the steel substrate of the provided or produced component is maintained at a temperature above Ac3 until the microstructure is fully or partially transformed into an austenitic microstructure,

(ii) mechanically shaping the component before, during and/or after the heat treatment,

(iii) the part is cooled from a temperature above Ac3, preferably to a temperature below 100 ℃, during and/or after mechanical forming, in order to obtain a martensitic structure in the steel substrate, preferably at a cooling rate > 20K/s,

and/or

The method comprises the following steps:

mechanical treatment, wherein the porosity of the corrosion protection coating and/or the metallic intermediate layer is reduced.

15. Use of titanium as a main constituent of a diffusion barrier between a steel substrate (3) whose microstructure can be transformed into a martensitic microstructure and an anti-corrosion protective coating (1) whose main constituent is zinc or manganese, preferably in a process for hardened, preferably press-hardened, parts, particularly preferably press-hardened parts of motor vehicles, very particularly preferably press-hardened parts selected from bumpers, side impact beams, pillars and body reinforcements.

Technical Field

The invention relates to a component comprising a steel substrate, a metallic intermediate layer covering the steel substrate and an anti-corrosion protective coating covering the intermediate layer. Further details regarding the components according to the invention emerge from the dependent claims and the following description. The invention also relates to a corresponding hardened part, a corresponding method for producing a hardened part and the use according to the invention. In each case, the details can be taken from the appended claims and the following description.

The component according to the invention is usually present in the form of a steel plate and is preferably present here in the form of a PHS steel plate (press hardened steel plate).

The hardened part according to the invention is preferably a steel moulding made of a corresponding press hardened steel plate.

Background

With regard to the designation "press hardened steel sheet" (or "PHS steel sheet"), reference may be made to DE 102012024616 a 1. As described therein, hardened parts with very high strength can be made from press hardened steel sheets by heating the steel sheets above the austenitizing temperature and obtaining a substantially pure martensitic structure by cooling during pressing.

However, the invention is not limited to the use of press hardened steel sheets (as components) or steel mouldings produced therefrom (as hardened components).

Within the scope of the invention, the steel substrate of the component and the respective hardened component is preferably a manganese boron steel. In the hot forming of such manganese boron steels, corrosion protection coatings, such as Al-Si coatings, are often used to prevent the formation of scale on the surface. However, such Al — Si coatings can only passively prevent corrosion due to their barrier effect. Due to the relatively low melting point of 419 ℃ of pure zinc, an actively protective zinc coating can be used only to a limited extent. It has been observed that during the forming process, liquid zinc penetrates into the substrate (steel substrate) and leads to crack formation (so-called liquid metal embrittlement) in this case. In some cases this problem has been solved by replacing the zinc coating with an alloy having a higher melting point, so that only a sufficiently small proportion of this alloy is present in liquid form during the hot forming process. Reference may again be made here to document DE 102012024616 a 1. Disclosed therein is a steel sheet, in particular a press-hardened steel sheet, having a steel substrate layer and an anti-corrosion protective layer containing zinc and manganese. The corrosion protection layer is applied here galvanically to the substrate layer and has a manganese proportion of at least 5 wt.%, but at most 25 wt.%. According to this disclosure, the manganese proportion should not exceed 25% by weight.

However, in general, in the case of zinc alloys, the sacrificial effect of the corrosion protection coating is generally lower than in the case of pure zinc. When the coated steel substrate is annealed, as is usually done in hot forming at about 900 ℃, iron also typically diffuses strongly into the coating composition (reference may also be made in this regard to the inventive study according to fig. 3). This inward diffusion generally further reduces the cathodic protection of the coating.

Such iron diffusion is generally undesirable.

WO 2014/124749 discloses a coated steel substrate having a metal Flash layer (Flash-Schicht) arranged thereon, wherein the metal Flash layer comprises a first Flash layer adjacent to the steel substrate and comprising one or more elements selected from the group consisting of Al, Ag, Au, Cr, Cu, Mo, Ni, Sn and Zr, and a second Flash layer comprising Fe as a main component.

DE 102014004656 a1 discloses a component having a base body made of thermoformable steel, which is provided, at least in some regions, with a coating comprising a first layer and at least one second layer which contains at least zinc and which is arranged on top of the first layer. Here, the first layer is arranged between the base body and the second layer and is formed as a liquid metal embrittlement and diffusion barrier. The first layer here preferably comprises non-noble metal oxides, nitrides, sulfides, carbides, hydrates, silicates, chromates, molybdates, tungstates, vanadates, titanates, borates, carbonates, chlorides or phosphate compounds.

EP 2049699B 1 relates to a method for coating a steel strip and a coated steel strip. The manganese content of the steel strip is in the range of 6-30%. Before the last annealing, an aluminum layer is applied to the steel strip, and after the last annealing, a coating consisting of molten metal is applied to the aluminum layer. The aluminium layer is preferably applied by PVD coating. The layer thickness of the intermediate layer is preferably limited to 50nm to 1000 nm. EP 2049699B 1 discloses that during the annealing process which is necessary before the subsequent melt coating, diffusion of iron from the steel strip into the applied aluminum occurs, so that during the annealing process a metal covering layer, which essentially consists of aluminum and iron, is present on the steel strip, which is connected in a positive manner to the substrate material formed from the steel strip.

EP 2435603B 1 discloses a method for producing a flat steel product which is formed from a base layer consisting of a steel material and a multi-layer coating applied thereto for protection against corrosion. Applying a zinc layer on a base layer in a specific manner, applying a specific aluminum layer on the surface of the zinc layer, applying a magnesium layer on top of the aluminum layer, and then carrying out a thermal post-treatment, wherein in the coating MgZn is formed above the Al layer in the direction of the coating surface₂And (3) a layer.

EP 2848709 a1 discloses a method for producing a steel component with a metal coating protected against corrosion and a steel component.

WO 2016/071399 a1 discloses a method for producing an anticorrosion protective coating for hardenable steel sheets and an anticorrosion protective coating for hardenable steel sheets.

WO 2015/090621 a1 discloses a steel substrate with a zinc-based corrosion protection coating. A diffusion barrier layer, which may preferably be a tungsten layer or a tungsten alloy layer, may be provided between the substrate and the zinc-based coating. It is disclosed that a relatively thin barrier layer having a thickness in the range of 2-50nm is sufficient.

Therefore, corrosion protection coatings and also, in part, intermediate layers or diffusion barriers for steel sheets (components) and hot-formed steel sheets (hardened components) are known from the prior art. However, the known corrosion protection coatings, intermediate layers, components and hardened components and their respective production methods are not yet optimal.

In particular, there is a great need for components having a steel substrate and an anticorrosion protective coating, in which the diffusion of iron from the steel substrate into the anticorrosion protective coating is at least largely suppressed.

Furthermore, there is a great need for components in which the diffusion of the elements of the corrosion protection coating into the steel substrate is particularly low.

There is a particular need for galvanized parts which are effectively protected against the effects of destructive zinc penetration during hot forming, so-called liquid metal embrittlement, which is often the cause of significant cracks forming in the substrate.

Furthermore, corresponding components are required, wherein, unlike the components in WO 2015/090621 a1, for example, no layer of a particularly brittle material (e.g. tungsten) is arranged on the steel substrate. The brittle layer is susceptible to cracking during subsequent thermoforming; the hardened steel sheet (hardened part) thus produced may exhibit unacceptable cracking.

Disclosure of Invention

The present invention addresses some or all of the above-mentioned goals or needs in various aspects that are interrelated through common technical teachings.

According to a main aspect of the present invention, which relates to a component (preferably a coated steel sheet), many of the above objects-problems are solved by a component comprising

A steel substrate whose structure can be transformed into a martensitic structure,

a metallic intermediate layer covering the steel substrate, the main component of which is titanium

And

-an anti-corrosion protective coating covering the intermediate layer,

wherein the corrosion protection coating comprises one or more layers and the one layer of the corrosion protection coating or at least the layer thereof adjacent to the metallic intermediate layer is metallic and of a different material than the intermediate layer.

The component according to the invention is generally suitable and arranged for further processing to obtain a hardened component according to the invention, as defined in more detail below and in the appended claims.

In this context, "metallic intermediate layer covering a steel substrate" is understood to be an intermediate layer in direct contact with the steel substrate. In other words, there is no other intervening layer disposed between the metallic interlayer and the steel substrate.

According to the invention, the main constituent of the metallic intermediate layer covering the steel substrate is titanium. This means that the mass proportion of titanium in the intermediate layer of metal is greater than the mass proportion of any other metal in the intermediate layer. The present invention is based (in all its aspects) on the surprising recognition that a metallic intermediate layer covering (contacting) a steel substrate and whose main component is titanium is an excellent diffusion barrier which greatly slows down the penetration of iron into the corrosion protection coating and also retards the penetration of conventional corrosion protection coating elements used for conventional process steps in the steel processing industry. In addition, the provision of a metallic intermediate layer whose main component is titanium does not increase the brittleness of the component, which would occur, for example, with a diffusion barrier layer consisting of a brittle metal such as tungsten. The component according to the invention is therefore largely protected against unacceptable consequences and unacceptable embrittlement resulting from excessive diffusion of iron in the direction of the corrosion protection coating and of elements of the corrosion protection coating in the direction of the steel substrate. Also, for example, effective protection against destructive zinc penetration, the so-called liquid metal embrittlement, is produced, which is often the cause of significant crack formation in the substrate (steel substrate) when zinc is present in the corrosion protection coating.

Preference is given to components according to the invention in which the main constituent of the metal atoms of the corrosion protection coating or of the metal atoms of the metal layer of the corrosion protection coating adjacent to the metal intermediate layer is selected from zinc and manganese

And/or

The metallic zinc and/or the metallic manganese are contained in one of the metallic layers of the corrosion protection coating or at least in the metallic layer thereof adjacent to the metallic intermediate layer.

The elements zinc and manganese are commonly used metal elements which are commonly used for corrosion protection coatings for steel sheets. Within the scope of the present invention, the use thereof is also preferred. Depending on the requirements of the individual case, it may be preferable in some cases to use zinc or to use manganese. In the research of the present invention, it has been found that the component according to the invention is useful irrespective of whether the main constituent of the metal atoms of the corrosion protection coating is zinc or manganese. For simplicity only, the following text focuses on the use of zinc; however, the embodiment with respect to zinc applies correspondingly also to the use of manganese.

In the component according to the invention (as described above, preferably as referred to as preferred above or below), the corrosion protection coating can in some places be in direct contact with the steel substrate at all, despite the presence of the metallic intermediate layer (substantially) covering the steel substrate. However, preference is given to a component according to the invention in which at least 90%, preferably at least 95%, of the area of the corrosion protection coating facing the steel substrate, preferably the entire area of the corrosion protection coating facing the steel substrate, is separated from the steel substrate by a metal intermediate layer.

It goes without saying that the direct advantage of the presence according to the invention of a metallic intermediate layer comprising titanium as main constituent and covering the steel substrate plays a role in the places where the corrosion protection coating does not come into direct contact with the steel substrate. For this reason, the person skilled in the art will generally take care to ensure that a large part of the area of the corrosion protection coating facing the steel substrate is separated from the steel substrate by the intermediate layer.

Preferred are components according to the invention (as described above, first of all referred to as preferred above) in which the steel substrate is a manganese-boron steel and/or a steel having a ferrite-pearlite structure, preferably a manganese-boron steel having a ferrite-pearlite structure, particularly preferably a manganese-boron steel having a ferrite-pearlite structure which can be transformed into a martensite structure by means of a heat hardening treatment, very particularly preferably a manganese-boron steel having a ferrite-pearlite structure which can be transformed into a martensite structure by means of a heat hardening treatment and a manganese proportion of less than 5 wt.%, preferably of 0.7 to 2 wt.%, the ferrite-pearlite structure being transformed into a martensite structure by means of a heat hardening treatment.

It is particularly advantageous for the purposes of the present invention for the steel used as steel substrate of the component according to the invention to be a manganese-boron steel (preferably with a ferritic-pearlitic structure) having a composition defined as follows:

0.07-0.4 wt% of C, 1.0-2.5 wt% of Mn, 0.06-0.9 wt% of Si, up to 0.03 wt% of P, up to 0.01 wt% of S, up to 0.1 wt% of Al, up to 0.15 wt% of Ti, up to 0.6 wt% of Nb, up to 0.005 wt% of B, up to 0.5 wt% of Cr, up to 0.5 wt% of Mo, wherein the total content of Cr and Mo is up to 0.5 wt%, the balance being iron and unavoidable impurities.

Particularly preferred are steel substrates (preferably with a ferritic-pearlitic structure) whose composition is defined as follows:

0.07-0.4 wt% of C, 1.0-2 wt% of Mn, 0.06-0.4 wt% of Si, up to 0.03 wt% of P, up to 0.01 wt% of S, up to 0.1 wt% of Al, up to 0.15 wt% of Ti, up to 0.6 wt% of Nb, up to 0.005 wt% of B, up to 0.5 wt% of Cr, up to 0.5 wt% of Mo, wherein the total content of Cr and Mo is up to 0.5 wt%, the balance being iron and unavoidable impurities.

Very particular preference is given to steel substrates (preferably having a ferritic-pearlitic structure) whose composition is defined as follows:

0.07-0.4 wt% of C, 1.0-1.5 wt% of Mn, 0.3-0.4 wt% of Si, up to 0.03 wt% of P, up to 0.01 wt% of S, up to 0.05 wt% of Al, up to 0.15 wt% of Ti, up to 0.6 wt% of Nb, up to 0.005 wt% of B, up to 0.5 wt% of Cr, up to 0.5 wt% of Mo, wherein the total content of Cr and Mo is up to 0.5 wt%, the balance being iron and unavoidable impurities.

The steel for steel substrates can be used either in pure form or in combination in the form of layers (3-5 layers of metal sheets on top of each other, which have been joined previously by a rolling process to form a steel strip) or joined steel sheets (e.g. a combination of two adjacent steel strips joined to form one steel strip, for example by laser welding) or in the form of slabs/tailored blanks.

The thickness of the steel substrate is preferably in the range of 0.6 to 7mm, more preferably in the range of 0.8 to 4mm and particularly preferably in the range of 0.8 to 3 mm. However, other thicknesses may be selected as required by the individual case.

For the purposes of the present invention, manganese proportions of more than 5% by weight in the steel substrate are not preferred in comparison with the preferred embodiments described above.

It is preferred to use a steel substrate adapted and arranged for hot forming. Thus, steel substrates having yield limits in the range of 250-580 MPa and/or tensile strengths in the range of 400-720 MPa are preferred.

Preference is given to a component according to the invention (preferably as referred to above as preferred component according to the invention) in which the proportion of titanium in the metallic intermediate layer covering the steel substrate is greater than or equal to 90% by weight, based on the total mass of the intermediate layer.

Surprisingly, a particularly effective diffusion barrier effect can be achieved with a metal intermediate layer whose main component is titanium and in which the proportion of titanium is preferably greater than or equal to 90% by weight, as compared with further examples hereinbelow.

Preference is given to a component according to the invention (preferably as referred to as preferred above) in which the material of the metallic intermediate layer, which covers the steel substrate and whose main constituent is titanium, is a material of

Having a melting point of more than 1000 ℃, preferably more than 1200 ℃, more preferably more than 1400 ℃, particularly preferably more than 1600 ℃,

and/or

-has a boiling point below 4700 ℃, preferably below 3500 ℃. In particular for applying the metallic intermediate layer to the steel substrate by means of a PVD process, the material of the intermediate layer should have one of the above-mentioned boiling points, which is below 3500 ℃.

Preference is given to components according to the invention (preferably as referred to above as preferred), in which

(i) The metallic zinc is contained in one of the metal layers of the corrosion-protection coating or at least in the metal layer adjacent to the intermediate metal layer, and

the proportion of metallic zinc in the corrosion protection coating covering the intermediate layer is greater than or equal to 55 wt.%, preferably greater than or equal to 96 wt.%, based on the total mass of the corrosion protection coating,

and/or

The melting point of the corrosion protection coating or of one metal layer of the corrosion protection coating or at least of the metal layer adjacent to the metal intermediate layer is greater than or equal to 419 ℃, preferably in the range from 419 ℃ to 580 ℃ or in the range above 600 ℃,

or even (this can be achieved in particular by the presence of manganese in the anticorrosion protective coating)

(ii) The melting point of the corrosion protection coating or of one of the metal layers of the corrosion protection coating or of at least the metal layer adjacent to the intermediate metal layer is greater than or equal to 880 ℃.

Surprisingly, the use according to the invention of a metal intermediate layer whose main component is titanium is associated with advantageous technical effects which are largely independent of the melting point of the corrosion protection coating or of one metal layer of the corrosion protection coating or of a metal layer at least adjacent to the metal intermediate layer. Since the component according to the invention is generally provided for the purpose of hot forming at temperatures greater than or equal to 880 ℃, in many cases metal layers with a low Zn proportion (and therefore preferably with a high Mn proportion) are economically more interesting than layers with a high Zn proportion. However, the technical effects of the present invention are not achieved in all cases.

In many cases, components are preferred (preferably as referred to above as preferred) in which the corrosion protection coating comprises a proportion of a manganese component

In the range from 15 to 40% by weight, based on the total mass of the anticorrosion protective coating

And/or

Greater than or equal to 27%, preferably greater than or equal to 30%,

and/or

Less than 40%, preferably less than 35%,

and/or

In the range of more than 25% to 40%, preferably in the range of more than 25% to 35%, particularly preferably in the range of 27% to 35%.

These corrosion protection coatings generally have high melting points and are therefore particularly suitable for thermoforming processes.

Preference is given to components according to the invention (preferably as referred to above as preferred), wherein

The intermediate layer of metal whose main component is titanium has a thickness of at most 500nm, preferably at most 400nm, particularly preferably at most 300nm,

and/or

The intermediate layer of metal, the main component of which is titanium, has a thickness of at least 100nm, preferably at least 150 nm.

The metal intermediate layer (based on titanium) of the component according to the invention can already effectively serve as a diffusion barrier even with very low layer thicknesses. Even a few atomic layers, i.e. for example only 1nm thick, effectively promote the diffusion barrier effect. For thicknesses exceeding 500nm, the studies of the present invention generally do not show relevant technical differences, so that metallic intermediate layers with thicknesses exceeding 500nm are advantageous only in exceptional cases.

Preference is given to components according to the invention (preferably as referred to above as preferred) in which the corrosion protection coating has a thickness of at least 1 μm, preferably in the range from 3 μm to 50 μm, particularly preferably in the range from 5 μm to 30 μm, very particularly preferably in the range from 7 μm to 20 μm.

Such thickness is set by the person skilled in the art in a conventional manner.

Preference is given to components according to the invention (preferably as referred to above as preferred), wherein

A metallic intermediate layer covering the steel substrate, the main component of which is titanium,

and/or

-the corrosion protection coating covering the intermediate layer is applied by physical vapour deposition.

One advantage of the present invention is that both the metallic intermediate layer and the corrosion protection coating covering the intermediate layer can be applied by Physical Vapor Deposition (PVD). Within the scope of the present invention, it is preferred to use a PVD process.

The invention also relates to a hardened part comprising

-steel substrate

-an anti-corrosion protective coating protecting the steel substrate, wherein the anti-corrosion protective coating comprises titanium, preferably metallic titanium.

Hardened parts according to the invention are preferably produced from parts according to the invention (preferably as referred to above as preferred).

During the conversion of the component according to the invention into a hardened component according to the invention (see below for an embodiment according to the invention), titanium migrates to some extent from the material of the metallic intermediate layer into the material of the corrosion protection coating. This results in an anticorrosion protective coating which protects the steel substrate and also comprises titanium, preferably metallic titanium. There is a significant difference here from the corrosion protection coatings known from the prior art. Although titanium migrates into the material of the corrosion protection coating during conventional hot forming processes for forming hardened parts starting from parts which have not yet been hardened, the diffusion barrier effect of the metallic intermediate layer (in particular the diffusion of iron into the corrosion protection coating and the diffusion of zinc and/or manganese into the steel substrate) is surprisingly excellent.

Preference is given to a hardened part according to the invention which can be obtained by hardening a part according to the invention (preferably as referred to above as preferred)

And/or

Is a thermoformed hardened part.

Hardened parts obtained by hardening the parts according to the invention by thermoforming are therefore particularly preferred.

Such a hardened part according to the invention is preferred (preferably as referred to above as preferred) wherein the steel substrate has mainly a martensitic structure. This means that other textures/phases may also be present, especially where appreciable proportions of zinc, manganese or titanium are present in the steel substrate as a result of convection or diffusion processes.

The martensitic structure present in the steel substrate in the preferred hardened component according to the invention may be produced in a conventional manner from a ferritic-pearlitic steel substrate by means of a hot forming process known to the person skilled in the art.

Such a hardened part according to the invention is preferred (preferably as referred to above as preferred), wherein the steel substrate is alloyed with titanium, preferably with titanium and at least one metal selected from zinc and manganese, in the region facing the anti-corrosion protective coating.

Such hardened parts are obtained in particular when, starting from a part according to the invention, titanium is diffused from the metal intermediate layer into the steel substrate to a certain (low) extent during hot forming or together with zinc and/or manganese (according to the above-described embodiments zinc and manganese are the preferred metals for the corrosion protection coating). The presence of titanium, zinc and/or manganese does not generally alter the fact that the microstructure of the steel substrate in the (preferred) hardened component according to the invention is martensitic. As described above, the martensite structure is preferable; the martensitic structure in the steel substrate is therefore particularly preferred, wherein the steel substrate is alloyed with titanium, zinc and/or manganese in the region facing the corrosion protection coating.

Preferably such a hardened part according to the invention, preferably as referred to above as preferred, wherein the steel substrate and the corrosion protection coating are connected by a transition zone,

and/or

-wherein the mass proportion of iron is reduced from the first mass proportion to half or less than half of the first mass proportion over a distance of at most 10 μm, preferably 5 μm in the direction of the corrosion protection coating, starting from the region of the transition zone close to the steel substrate, wherein the first mass proportion of iron is preferably at least 80% by weight in the region of the transition zone close to the steel substrate.

Surprisingly, it is possible to manufacture hardened parts according to the invention by means of a method according to the invention (as defined below and in the appended claims) which has a transition zone having one or both of the properties defined above. In the transition zone, in the preferred hardened component, the metal main constituent is thus changed and/or the iron mass proportion is reduced only over a very short distance of at most 10 μm. These characteristics of the (very narrow) transition zone can be attributed to the excellent diffusion barrier effect of the titanium-based metallic intermediate layer present in the (still unhardened) component according to the invention.

Such a hardened part according to the invention is preferred (preferably as referred to above as preferred), wherein the proportion of iron, measured from the outer surface of the corrosion protection coating, in the corrosion protection coating is less than 25 wt.%, preferably less than 20 wt.%, determined by GDOES, to a depth of 2 μm, preferably in the range of 1-3 μm. Therefore, hardened parts according to the invention are preferred in which iron does not migrate to a decisive extent into the corrosion protection coating during production and during any post-treatment. The proportion of iron was determined by GDOES according to ISO standard 11505:2012 ("surface chemistry analysis-general procedure for quantitative component depth analysis by glow discharge emission spectroscopy"). In this measurement method, plasma is generated by applying a high voltage to a glow discharge lamp filled with argon gas. By means of the plasma, on the one hand ions are generated for the sputtering process (to remove the surface to be examined) and on the other hand the removed atoms are excited to emit radiation. The emitted light is spectrally resolved in a polychromator and the light intensity is converted into electrical signals by a photomultiplier. These signals are subsequently digitized and evaluated in a PC-assisted control and evaluation unit.

Such a hardened part according to the invention is preferred (preferably as referred to above as preferred), wherein a maximum of the titanium mass fraction is present in the mass fraction-depth map (quantitative depth curve) at a depth of > 0 μm, preferably in the range of 2 to 20 μm, measured from the outer surface of the corrosion protection coating.

Although titanium generally diffuses to some extent into the corrosion protection coating during the production of the hardened part according to the invention from the (still unhardened) part, for example by thermoforming, a state is not sought or reached in which the titanium concentration at the outer surface of the corrosion protection coating is as high as in the interior of the hardened part, which is advantageous.

The invention also relates to a method for producing a component, preferably for producing a component according to the invention (preferably as referred to above as preferred). The method according to the invention comprises the following steps:

-producing or providing a steel substrate, wherein the microstructure of the steel substrate may be transformed into a martensitic microstructure,

applying (i) titanium or (ii) titanium and one or more other metals onto a steel substrate to form a metallic interlayer covering the steel substrate and having a major component of titanium,

-applying one or more metals onto the intermediate layer of metal to form an anticorrosion protective coating covering the intermediate layer.

The embodiments described above apply correspondingly with regard to the preferred steel substrate and the preferred metal for forming the corrosion protection coating covering the intermediate layer and the preferred properties of the resulting component. On the contrary, all embodiments above or below in connection with the method according to the invention are correspondingly applicable to the component or hardened component according to the invention.

In general, for all aspects of the invention explained within the scope herein, the preferred embodiments presented for one of these aspects are also applicable to the other aspects with corresponding changes.

The titanium or titanium and one or more other metals may be applied to the steel substrate and the one or more metals to the metal intermediate layer in different ways. Preference is given to a process according to the invention in which the application of the metal layer or layers is carried out by a process selected from the group consisting of: electrolytic deposition, electroplating, physical vapor deposition, chemical vapor deposition, dipping process, slurry process, thermal spray and combinations thereof, preferably electrolytic or by physical vapor deposition, particularly preferably by physical vapor deposition.

As mentioned above, the main component of the corrosion protection coating in the component according to the invention is preferably zinc or manganese. It is therefore preferred that the method according to the invention (preferably as referred to above as preferred) comprises the steps of:

-applying (i) zinc or (ii) zinc and one or more other metals onto the intermediate layer of metal to form an anticorrosion protective coating covering the intermediate layer and having zinc as its main component

-applying (i) manganese or (ii) manganese and one or more other metals onto the intermediate layer of metal to form an anticorrosion protective coating covering the intermediate layer and whose main component is manganese.

Preferably the process according to the invention (preferably as referred to above as preferred) wherein (i) titanium or (ii) titanium and one or more further metals are applied to the steel substrate and the one or more further metals are applied to the metal interlayer such that at least 90%, preferably at least 95%, particularly preferably the entire face of the corrosion protection coating facing the steel substrate is separated from the steel substrate by the metal interlayer.

The advantages and effects presented above in connection with the respective preferred components according to the invention apply.

Preference is given to a process according to the invention (preferably as referred to above as preferred) in which the steel substrate is a manganese-boron steel and/or a steel having a ferrite-pearlite structure, preferably a manganese-boron steel having a ferrite-pearlite structure, particularly preferably a manganese-boron steel having a ferrite-pearlite structure which can be transformed into a martensitic structure by a heat hardening treatment, very particularly preferably a manganese-boron steel having a ferrite-pearlite structure which can be transformed into a martensitic structure by a heat hardening treatment and a manganese proportion of less than 5 wt.%, preferably of from 0.7 to 2 wt.%.

The effects and advantages presented above in connection with the component according to the invention are also achieved here.

Preference is given to a process according to the invention (preferably as referred to above as preferred) in which the proportion of titanium is selected at the time of application of (i) titanium or (ii) titanium and one or more other metals into the steel substrate so that the proportion of titanium in the resulting metal interlayer covering the steel substrate is greater than or equal to 90% by weight, based on the total mass of the interlayer.

The effects and advantages presented above in connection with the component according to the invention are also achieved here.

Preference is given to a process according to the invention (preferably as referred to above as preferred) in which the type and amount of metal to be applied to produce the metal interlayer is selected such that the resulting material covering the metal interlayer of the steel substrate, the main component of which is titanium

Having a melting point of more than 1000 ℃, preferably more than 1200 ℃, preferably more than 1400 ℃, particularly preferably more than 1600 ℃,

and/or

-has a boiling point below 4700 ℃, preferably below 3500 ℃.

The embodiments described above apply accordingly.

Particular preference is given to a process according to the invention (preferably as referred to above as preferred), in which

The proportion of zinc is chosen when (i) zinc or (ii) zinc and one or more other metals are applied to the metallic intermediate layer such that the proportion of zinc in the corrosion protection coating covering the intermediate layer is greater than or equal to 55% by weight, based on the total weight of the corrosion protection coating,

The proportion of manganese is selected when (i) manganese or (ii) manganese and one or more further metals are applied to the metal intermediate layer such that the melting point of the corrosion protection coating or of the metal layer of the corrosion protection coating at least adjacent to the metal intermediate layer is greater than or equal to 880 ℃.

Preferably such a method according to the invention (preferably as referred to above as preferred) comprises applying (ii) zinc and manganese and possibly one or more other metals to the metallic interlayer to produce an anti-corrosion protective coating covering the interlayer, the main component of which is zinc and comprises manganese,

wherein the amounts of zinc and manganese and possibly one or more other metals to be applied are preferably selected such that the resulting corrosion protection coating contains a proportion of manganese

In the range from 15 to 40% by weight, based on the total mass of the resulting corrosion protection coating

And/or

Based on the total mass of manganese and zinc in the resulting corrosion protection coating

Greater than or equal to 27%, preferably greater than or equal to 30%,

and/or

Less than 40%, preferably less than 35%,

and/or

In the range of more than 25% to 40%, preferably in the range of more than 25% to 35%, particularly preferably in the range of 27% to 35%.

The embodiments described above apply accordingly.

Preferably a method according to the invention (preferably as referred to above as preferred), wherein

The resulting intermediate metal layer, the main component of which is titanium, has a thickness of up to 500nm, preferably a thickness of up to 400nm, particularly preferably a thickness of up to 300nm,

and/or

The resulting metal intermediate layer, the main component of which is titanium, has a thickness of at least 100nm, preferably at least 150 nm.

The embodiments described above apply accordingly.

Preference is given to a process according to the invention (preferably as referred to above as preferred) in which the resulting corrosion-protective coating whose main component is zinc has a thickness of at least 1 μm, preferably in the range from 3 μm to 50 μm, more preferably in the range from 5 μm to 30 μm, particularly preferably in the range from 7 μm to 20 μm.

The embodiments described above apply accordingly.

Preference is given to a method according to the invention (preferably as referred to above as preferred), in which

-applying (i) titanium or (ii) titanium and one or more other metals onto a steel substrate, so as to obtain a metallic intermediate layer covering the steel substrate, the main constituent of which is titanium

And/or

Applying one or more other metals to the intermediate layer of metal, so as to obtain an anticorrosion protective coating covering the intermediate layer,

the above application is performed by physical vapor deposition. Such physical vapor deposition is preferably carried out under conditions,

at an oxygen partial pressure of less than 0.1mbar, preferably less than 0.01mbar, particularly preferably less than 0.001mbar,

and/or

In such a gas phase, the proportion by volume of oxygen is less than 20% by volume, preferably less than 10% by volume, particularly preferably less than 1% by volume.

The invention also relates to a method for producing a hardened part, comprising the following steps:

providing a component according to the invention or producing a component by a method according to the invention (as defined above and/or in the appended claims, respectively, preferably as referred to herein as preferred),

-treating the provided or produced component to obtain a hardened component.

The above-described embodiments with respect to the preferred component, method and hardened component according to the invention apply accordingly.

Preference is therefore given to a method according to the invention (preferably as referred to above as preferred), wherein the component provided or produced comprises a steel as steel substrate, which steel has a microstructure that can be transformed into a martensitic microstructure, preferably a steel having a ferritic-pearlitic microstructure, particularly preferably a manganese-boron steel having a ferritic-pearlitic microstructure, and the treatment comprises:

a heat hardening treatment for transforming the structure into a martensitic structure,

and preferably comprises

Mechanical treatment, preferably mechanical forming, carried out before, during and/or after (preferably during) the thermal hardening treatment.

Preference is given to a method according to the invention (preferably as referred to above as preferred) in which treatment is carried out

At least comprises the following steps:

(ii) mechanically shaping the component before, during and/or after the heat treatment,

and/or

The method comprises the following steps:

mechanical treatment, wherein the porosity of the corrosion protection coating and/or the metallic intermediate layer is reduced.

The invention also relates to the use of titanium as a main constituent of a diffusion barrier layer between a steel substrate whose microstructure can be transformed into a martensitic microstructure and an anti-corrosion protective coating whose main constituent is zinc or manganese, preferably zinc. It has surprisingly been found that the use of titanium as the main component of the diffusion barrier layer leads to particularly excellent results and technical effects, which have hitherto not been known in the prior art. These are reflected in particular in a significantly reduced diffusion in the hot forming process starting from the component according to the invention to obtain a hardened component according to the invention.

The advantages associated with the component according to the invention, the hardened component according to the invention and the method according to the invention and the technical effects presented here are correspondingly applicable to the use according to the invention.

The use according to the invention is preferably used in a method for producing hardened, preferably press-hardened parts of motor vehicles, particularly preferably press-hardened parts selected from bumpers, side impact beams, pillars and body reinforcements.

Finally, the invention also relates to the use of a component according to the invention for producing a hardened component according to the invention.

Preferred aspects of the invention are given next; the reference numerals are based on the figures and will be explained in more detail below.

1. Component of which comprises

A steel substrate (3) whose structure can be transformed into a martensitic structure,

-a metallic intermediate layer (2) covering the steel substrate, the main component of which is titanium

And

-an anti-corrosion protective coating (1) covering the intermediate layer (2),

2. The member according to aspect 1, wherein

And/or

3. Component according to any one of the preceding aspects, wherein at least 90%, preferably at least 95%, more preferably the entire surface facing the steel substrate (3) of the area of the corrosion protection coating (1) facing the steel substrate (3) is separated from the steel substrate (3) by the metallic intermediate layer (2).

4. The component according to any one of the preceding aspects, wherein the steel substrate (3) is a manganese-boron steel and/or a steel having a ferrite-pearlite structure,

preferably a manganese-boron steel having a ferrite-pearlite structure,

particularly preferred is manganese-boron steel having a ferrite-pearlite structure which can be transformed into a martensite structure by a heat hardening treatment,

very particular preference is given to manganese-boron steels having a ferritic-pearlitic structure and a manganese proportion of less than 5% by weight, preferably from 0.7 to 2% by weight, the structure of which can be transformed into a martensitic structure by means of a heat hardening treatment.

5. Component according to any one of the preceding aspects, wherein the proportion of titanium in the metallic intermediate layer (2) covering the steel substrate (3) is greater than or equal to 90% by weight, based on the total mass of the intermediate layer (2).

6. The component according to any one of the preceding aspects, wherein the material of the metallic intermediate layer (2) covering the steel substrate and whose main component is titanium,

having a melting point of more than 1000 ℃, preferably more than 1200 ℃, preferably more than 1400 ℃, particularly preferably more than 1600 ℃,

and/or

-has a boiling point below 4700 ℃, preferably below 3500 ℃.

7. The component of any one of the preceding aspects, wherein

(i) Metallic zinc is present in one of the metal layers of the corrosion protection coating (1) or at least in the metal layer thereof adjacent to the intermediate metal layer (2), and

and/or

8. Component according to any one of the preceding aspects, wherein the corrosion protection coating (1) comprises manganese in a proportion

In the range from 15 to 40% by weight, based on the total mass of the anticorrosion protective coating

And/or

Greater than or equal to 27%, preferably greater than or equal to 30%,

and/or

Less than 40%, preferably less than 35%,

and/or

In the range of more than 25% to 40%, preferably in the range of more than 25% to 35%, particularly preferably in the range of 27% to 35%.

9. The component of any one of the preceding aspects, wherein

The intermediate layer (2) of metal whose main component is titanium has a thickness of at most 500nm, preferably at most 400nm, particularly preferably at most 300nm,

and/or

The metal intermediate layer (2) whose main component is titanium has a thickness of at least 100nm, preferably at least 150 nm.

10. Component according to any one of the preceding aspects, wherein the corrosion protection coating (1) has a thickness of at least 1 μm, preferably a thickness in the range of 3 μm to 50 μm, particularly preferably a thickness in the range of 5 μm to 30 μm, very particularly preferably a thickness in the range of 7 μm to 20 μm.

11. The component of any one of the preceding aspects, wherein

-a metallic intermediate layer (2) covering the steel substrate, the main component of which is titanium

And/or

-a corrosion protection coating (1) covering said intermediate layer

Applied by physical vapor deposition.

12. Hardened part comprising

-a steel substrate (6) and

-an anti-corrosion protective coating (4) protecting the steel substrate, wherein the anti-corrosion protective coating comprises titanium, preferably metallic titanium.

13. The hardened member according to aspect 12, wherein said hardened member

Obtainable by hardening a component according to any one of aspects 1 to 11

And/or

Is a thermoformed hardened part.

14. A hardened part according to any one of aspects 12 and 13, wherein the steel substrate (6) has mainly a martensitic structure.

15. A hardened part according to any one of aspects 12 to 14, wherein the steel substrate (6) is alloyed with titanium, preferably with titanium and at least one metal selected from zinc and manganese, in the region facing the anti-corrosion protective coating (4).

16. The hardened part according to any one of aspects 12 to 15, wherein the steel substrate (6) and the corrosion protection coating (4) are connected by a transition zone (5)

and/or

17. The hardened part according to any one of aspects 12 to 16, wherein the proportion of iron, measured from the outer surface of the corrosion protection coating, in the corrosion protection coating (4) at a depth of 2 μm, preferably in the range of 1-3 μm, is less than 25 wt.%, preferably less than 20 wt.%, determined by GDOES.

18. The hardened part according to any one of aspects 12 to 17, wherein there is a maximum value of the titanium mass fraction determined by GDOES in the mass fraction-depth map at a depth > 0 μm, preferably in the range of 2 to 20 μm, measured from the outer surface of the corrosion protection coating (4).

19. Method for producing a component, preferably a component according to any of aspects 1 to 12, comprising the steps of:

-producing or providing a steel substrate (3), wherein the microstructure of the steel substrate may be transformed into a martensitic microstructure,

-applying one or more metals onto the metallic intermediate layer to form an anti-corrosion protective coating (1) covering the intermediate layer.

20. The method according to aspect 19, comprising the steps of:

-applying (i) zinc or (ii) zinc and one or more other metals to the intermediate layer of metal to form a corrosion protection coating (1) covering the intermediate layer and whose main component is zinc

-applying (i) manganese or (ii) manganese and one or more other metals onto said metallic intermediate layer to form an anticorrosion protective coating (1) covering the intermediate layer and whose main component is manganese.

21. The method according to aspect 19 or 20, wherein (i) titanium or (ii) titanium and one or more other metals are applied onto the steel substrate (3) and one or more other metals are applied onto the metallic intermediate layer (2) such that at least 90%, preferably to 95%, particularly preferably the entire face of the area of the corrosion protection coating (1) facing the steel substrate is separated from the steel substrate (3) by the metallic intermediate layer (2).

22. The method according to any one of aspects 19 to 21, wherein the steel substrate (3) is a manganese boron steel and/or a steel having a ferrite-pearlite structure,

preferably a manganese-boron steel having a ferrite-pearlite structure,

particularly preferred is manganese-boron steel having a ferrite-pearlite structure which can be transformed into a martensite structure by a heat hardening treatment,

very particular preference is given to manganese-boron steels having a ferritic-pearlitic structure which can be transformed into a martensitic structure by means of a heat-hardening treatment and a manganese proportion of less than 5% by weight, preferably from 0.7 to 2% by weight.

23. The method according to any one of aspects 19 to 22, wherein the proportion of titanium is selected when applying (i) titanium or (ii) titanium and one or more other metals into the steel substrate (3) such that the proportion of titanium in the resulting metal interlayer (2) covering the steel substrate (3) is greater than or equal to 90 wt.%, based on the total mass of the interlayer (2).

24. The method according to any one of aspects 19 to 23, wherein the type and amount of metal to be applied to produce the metallic intermediate layer (2) is selected such that the resulting material of the metallic intermediate layer (2) covering the steel substrate (3) whose main component is titanium

Having a melting point of more than 1000 ℃, preferably more than 1200 ℃, preferably more than 1400 ℃, particularly preferably more than 1600 ℃,

and/or

-has a boiling point below 4700 ℃, preferably below 3500 ℃.

25. The method according to any one of aspects 19 to 24, wherein

The proportion of zinc is chosen when (i) zinc or (ii) zinc and one or more other metals are applied to the intermediate layer (2) of metal such that the proportion of zinc in the corrosion protection coating (1) covering the intermediate layer (2) is greater than or equal to 55% by weight, based on the total weight of the corrosion protection coating,

The proportion of manganese is selected when (i) manganese or (ii) manganese and one or more further metals are applied to the intermediate metal layer (2) in such a way that the melting point of the corrosion protection coating or of the metal layer of the corrosion protection coating (1) at least adjacent to the intermediate metal layer (2) is greater than or equal to 880 ℃.

26. The method according to any one of aspects 19 to 25, comprising applying (ii) zinc and manganese and possibly one or more other metals to a metallic intermediate layer to produce an anticorrosion protective coating (1) covering the intermediate layer, the main component of which is zinc and comprises manganese,

wherein the amounts of zinc and manganese and possibly one or more other metals to be applied are preferably selected such that the resulting corrosion protection coating (1) comprises a proportion of manganese, which proportion is

-in the range of 15 to 40 wt. -%, based on the total mass of the resulting corrosion protection coating (1)

And/or

Based on the total mass of manganese and zinc in the resulting corrosion protection coating (1)

Greater than or equal to 27%, preferably greater than or equal to 30%,

and/or

Less than 40%, preferably less than 35%,

and/or

In the range of more than 25% to 40%, preferably in the range of more than 25% to 35%, particularly preferably in the range of 27% to 35%.

27. The method according to any one of aspects 19 to 26, wherein

The resulting metal intermediate layer (2) whose main component is titanium has a thickness of up to 500nm, preferably a thickness of up to 400nm, particularly preferably a thickness of up to 300nm,

and/or

The resulting metal intermediate layer (2) whose main component is titanium has a thickness of at least 100nm, preferably at least 150 nm.

28. The process according to any one of aspects 19 to 27, wherein the resulting corrosion protection coating (1) whose main component is zinc has a thickness of at least 1 μm, preferably in the range from 3 μm to 50 μm, more preferably in the range from 5 μm to 30 μm, particularly preferably in the range from 7 μm to 20 μm.

29. The method according to any one of aspects 19 to 28,

wherein

And/or

-applying one or more other metals to the intermediate layer of metals, so as to obtain an anticorrosion protective coating (1) covering the intermediate layer,

the above application is carried out by physical vapor deposition, preferably under the following conditions

At an oxygen partial pressure of less than 0.1mbar, preferably less than 0.01mbar, particularly preferably less than 0.001mbar,

and/or

In the gas phase, the proportion by volume of oxygen is less than 20% by volume, preferably less than 10% by volume, particularly preferably less than 1% by volume.

30. Method for producing a hardened part, preferably a hardened part according to any one of the aspects 12 to 18, comprising the steps of:

-providing a component according to any of aspects 1 to 12 or producing a component by a method according to any of aspects 20 to 31,

-treating the provided or produced component to obtain a hardened component.

31. The method according to aspect 30, wherein the provided or produced component comprises as a steel substrate (3) a steel having a structure that can be transformed into a martensitic structure, preferably a steel having a ferritic-pearlitic structure, particularly preferably a manganese-boron steel having a ferritic-pearlitic structure, and the treatment comprises:

a heat hardening treatment for transforming the structure into a martensitic structure,

and preferably comprises

Mechanical treatment, preferably mechanical forming, before, during and/or after the thermosetting treatment.

32. The method according to any one of aspects 30 and 31, wherein the treating is

At least comprises the following steps:

(ii) mechanically shaping the component before, during and/or after the heat treatment,

and/or

The method comprises the following steps:

mechanical treatment, wherein the porosity of the corrosion protection coating and/or the metallic intermediate layer is reduced.

33. Use of titanium as a main constituent of a diffusion barrier layer between a steel substrate (3) whose structure can be transformed into a martensitic structure and an anti-corrosion protective coating (1) whose main constituent is zinc or manganese.

34. The use according to aspect 33 in a method for press hardening, preferably press hardening, parts, preferably press hardening of motor vehicles, particularly preferably selected from bumpers, side impact beams, pillars and body reinforcements.

35. Use of a component according to any one of aspects 1 to 11 for producing a hardened component according to any one of aspects 12 to 18.

Drawings

Fig. 1 schematically shows a part according to the invention, comprising a steel substrate (3) whose microstructure is transformed into a martensitic microstructure, a metallic intermediate layer (2) covering the steel substrate and having titanium as the main component, and an anticorrosion protective coating (1) covering the intermediate layer (2). Details of exemplary components according to the present invention can be found in example 1 below.

Fig. 2 schematically shows a hardened part according to the invention, which is present after heat treatment (hot forming) of the part according to the invention, wherein the steel substrate (6) and the corrosion protection coating (4) are connected by means of a transition zone (5), see example 2 below.

Fig. 3, 4 and 5 show a summary computational graph based on exemplary experimental raw data.

Fig. 3 shows GDOES measurements (according to ISO 11505:2012) for elemental iron (Fe) performed on a part according to the invention, a hardened part according to the invention and as a comparison a hardened part not according to the invention. The X-axis represents distance (i.e., depth) from the sample surface in microns. The Y-axis represents the proportion by mass of iron (expressed in percentage) in the respectively examined sample volume.

The solid line [0min. (Ti) ] represents the measured values determined on the component according to the invention (with an intermediate layer consisting of titanium). As the steel substrate, a 22MnB5 substrate was used; the metal intermediate layer (2) which covers the steel substrate and contains titanium as a main component is composed of titanium (contains only unavoidable impurities); and the corrosion protection coating (1) covering the intermediate layer (2) consists of zinc (containing only unavoidable impurities). The solid lines in fig. 3 correspond to the solid lines in fig. 4 and 5; the measurement points on which the solid lines in fig. 3, 4 and 5 are based are from a common GDOES measurement, respectively.

The dashed line [5min. (Ti) ] represents the measured values determined on the hardened part according to the invention. The hardened parts measured were obtained by thermoforming from parts according to the invention at 880 ℃ and a holding time of 5 minutes. The dashed lines in fig. 3 correspond to the dashed lines in fig. 4 and 5; the measurement points on which the dashed lines in fig. 3, 4 and 5 are based are respectively from a common GDOES measurement.

The dotted line [5min. ] represents the measured values measured on a hardened part not according to the invention obtained by thermoforming at 880 ℃ and a holding time of 5 minutes from a corresponding part not according to the invention (without the titanium intermediate layer). The steel substrate (3) herein is, for example, a 22MnB5 substrate; in this case, there is no intermediate metal layer (2) covering the steel substrate, but rather the corrosion protection coating (1), which here consists of zinc, for example, is in direct contact with the steel substrate. The experimental results of the corresponding components not according to the invention are not shown in fig. 3. The chain line in fig. 3 corresponds to the chain line in fig. 4; the measurement points on which the dashed lines in fig. 3 and 4 are based are from a common GDOES measurement, respectively.

Fig. 4 shows GDOES measurements (according to ISO 11505:2012) on components according to the invention, hardened components according to the invention and, as a comparison, hardened components not according to the invention for elemental zinc (Zn). The X-axis represents distance (i.e., depth) from the sample surface in microns. The Y-axis represents the proportion by mass of zinc (expressed as a percentage) in the respectively examined sample volume.

The dotted line [5min. ] represents the measured values measured on a hardened part not according to the invention, obtained by thermoforming from the respective part at 880 ℃ with a holding time of 5 minutes. The steel substrate (3) herein is, for example, a 22MnB5 substrate; in this case, there is no intermediate metal layer (2) covering the steel substrate, but rather the corrosion protection coating (1), which here consists of zinc, for example, is in direct contact with the steel substrate. The experimental results of the corresponding components not according to the invention are not shown in fig. 4.

Fig. 5 shows GDOES measurements (according to ISO 11505:2012) on a part according to the invention, a hardened part according to the invention, for elemental titanium (Ti). The X-axis represents distance (i.e., depth) from the sample surface in microns. The Y-axis represents the proportion by mass (in percent) of titanium in the respective examined sample volumes.

The solid line [0min. (Ti) ] represents the measured values determined on the component according to the invention (with an intermediate layer consisting of titanium). As the steel substrate, a 22MnB5 substrate was used; the metal intermediate layer (2) which covers the steel substrate and contains titanium as a main component is composed of titanium (contains only unavoidable impurities); and the corrosion protection coating (1) covering the intermediate layer (2) consists of zinc (containing only unavoidable impurities). The solid lines in fig. 5 correspond to the solid lines in fig. 3 and 4; the measurement points on which the solid lines in fig. 3, 4 and 5 are based are from a common GDOES measurement, respectively.

Detailed Description

Example 1-production and testing of Components according to the invention

A metal intermediate layer composed of Ti (as an example of a metal intermediate layer covering a steel substrate and whose main component is Ti) was applied to the provided 22MnB5 substrate (having a ferrite-pearlite structure as an example of a steel substrate whose structure is convertible to a martensite structure) at a thickness of about 250nm by Physical Vapor Deposition (PVD). The application is carried out by physical vapour deposition at an oxygen partial pressure of less than 0.001 mbar. The application of the metal intermediate layer consisting of titanium by physical vapour deposition is controlled in such a way that at least 95% of the area of the steel substrate is covered by the metal intermediate layer.

A single Zn layer of about 5 μm thickness is applied over the metallic interlayer (as an example of an anti-corrosion protective coating covering the interlayer; as the studies of the invention show, the use of manganese or a zinc-manganese alloy is equally advantageous).

Fig. 1 schematically shows the resulting structure of an exemplary produced component, with a steel substrate (3), a metallic intermediate layer (2) covering the steel substrate and whose main component is titanium, and an anticorrosion protective coating (1) covering the intermediate layer (2). The metal intermediate layer is coated with the corrosion protection coating in such a way that at least 95% of the surface of the corrosion protection coating (1) facing the steel substrate (3) is in contact with the metal intermediate layer (2) and is thereby separated from the steel substrate (3).

The illustrated embodiments represent exemplary methods according to the invention for producing components according to the invention.

Detecting the component thus obtained by GDOES measurement; the results are shown in solid lines (for iron, zinc or titanium) in fig. 3, 4 and 5.

The measurements show that zinc is the only metal detected at the surface of the part and that no more zinc is detected from a depth of about 5 μm. Iron can only be detected from a sample depth of 3 μm and from a depth of about 5 μm as the only one that can be detected in the metal considered here.

The measured value of titanium (as the material of the intermediate layer) has a maximum at a depth of about 4 μm. The titanium mass proportion determined with the aid of GDOES does not reach 100% here; this is due in particular to the large lateral extension of the measurement point (diameter about 4mm) relative to the layer thickness, whereby the signal is significantly broadened in terms of depth resolution. Thus, due to the chosen measurement method, the relative mass fraction of titanium in the separately sampled volumes is underestimated.

Not all the places along the depth curve, the proportions by mass of the elements iron, zinc and titanium applied add up to 100%. The reason for this is, in particular, that zinc is oxidized, in particular on the surface, that is to say oxygen is also present here in the layer. For clarity, the proportion of oxygen is not shown in figures 3, 4 and 5.

EXAMPLE 2 production and testing of hardened parts according to the invention

2.1 production of the component according to the invention:

firstly, a part differing from the part described in example 1 only in terms of the thickness of the Zn corrosion protection coating is produced; in contrast to the about 5 μm Zn anticorrosion protection coating thickness selected in example 1, a thickness of about 10 μm is selected for the Zn anticorrosion protection coating. This way the analytical results are easier to compare, since in the investigation of the invention the thickness of the Zn corrosion protection coating applied by means of PVD is reduced to about half by compression (porosity reduction) and evaporation of zinc during hot forming. Thus, the thicknesses of the Zn corrosion protection coatings of the part of example 1 (not thermoformed) and the hardened part of example 2 (post-thermoformed) substantially correspond to each other.

2.2 production of hardened parts according to the invention by thermoforming

The component according to the invention produced according to 2.1 is hardened in a hot forming process with a holding time of, for example, 5 minutes at 880 ℃ (in order to form an austenitic structure completely or partially in the steel substrate) and subsequently hardened by cooling to a hardened component according to the invention with a martensitic structure. Fig. 2 schematically shows the structure of the resulting hardened part according to the invention.

GDOES detection

Inspecting the hardened part according to the invention by GDOES; the results are shown in dashed lines in fig. 3, 4 and 5. The measurement results show that in the component according to the invention, in which iron, titanium and zinc are present, a transition zone is present in which the metal main constituent changes in the direction of the corrosion protection coating, from the region of the transition zone close to the steel substrate, from iron to zinc. The transition zone connects the steel substrate and the corrosion protection coating. These characteristics of the (very narrow, here approximately 5 μm thick) transition zone can be attributed to the excellent diffusion barrier effect of the metallic intermediate layer consisting of titanium present in the component according to the invention (see point 2.1). The measurements clearly show that iron, zinc and titanium are present as an alloy in the region of the transition zone facing the steel substrate (when manganese is selected as a constituent of the corrosion protection coating according to the invention, manganese can equally advantageously be a constituent of this alloy instead of or in addition to zinc). The proportion of iron by mass at a depth of about 2 μm, measured from the outer surface of the corrosion protection coating, is less than 5% (see fig. 3). The mass proportion of titanium has a maximum at a depth of 3 to 5 μm, measured from the outer surface of the corrosion protection coating (see fig. 5).

2.4. Comparison/evaluation/conclusion:

the product according to the invention is characterized by a strongly reduced penetration of zinc into the steel substrate compared to a comparative or hardened component which is otherwise structurally similar but does not comprise an intermediate layer (diffusion barrier layer) consisting of titanium or does not comprise a transition zone. At the same time, in the product according to the invention, the migration of iron from the steel substrate into the corrosion protection coating is significantly reduced. Typical curves for the comparative product (without intermediate layer) are plotted in fig. 3 and 4 for thermoforming at 880 ℃ and a holding time of 5 minutes, respectively. It will be seen by the person skilled in the art that the interpenetration of zinc and iron in the comparative product is much more obvious than in the product according to the invention. In the product according to the invention, the intermediate layer (diffusion barrier layer) consisting of titanium thus largely prevents such interpenetration.

Example 3

The hardened parts produced in example 2.2 and analyzed by means of GDOES according to example 2.3 were subjected to a supplementary wet-chemical analysis. For this purpose, the corrosion protection coating is dissolved in an acid and then analyzed by means of IPC-OES (inductively coupled plasma emission Spectroscopy) in accordance with DIN EN ISO 11885: 2009-09. The proportion of Fe in the corrosion protection coating (after 5 minutes of annealing) was determined to be (3.2 ± 0.1) wt.%, based on the elements observed for zinc, iron, aluminum, titanium and manganese. The results also clearly show that the metallic intermediate layer consisting of titanium prevents, at least to a large extent, the diffusion of iron from the steel substrate into the corrosion protection coating.

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Component comprising a steel substrate, an intermediate layer and an anti-corrosion protective coating, corresponding hardened component, and corresponding method and use

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