WO2016071399A1

WO2016071399A1 - Method for producing an anti-corrosion coating for hardenable steel sheets and anti-corrosion layer for hardenable steel sheets

Info

Publication number: WO2016071399A1
Application number: PCT/EP2015/075702
Authority: WO
Inventors: Siegfried Kolnberger; Ernst Commenda
Original assignee: Voestalpine Stahl Gmbh
Priority date: 2014-11-04
Filing date: 2015-11-04
Publication date: 2016-05-12
Also published as: EP3215656A1; EP3215656B1; DE102015118869A1; US20170321314A1

Abstract

The invention relates to a method for producing an anti-corrosion coating for hardenable steel sheet, wherein at least two metal layers are deposited, one after the other, on the steel substrate, wherein one metal layer is a layer made of zinc or based on zinc and the other layer is a layer made of a metal that is formed having Zn or Fe intermetallic base metal phases and having a higher oxidation potential than Zn, namely Ni, Cu, Co, Mn or Mo, or is a layer based on said metals, and an anti-corrosion layer for hardenable steel sheets.

Description

Method for producing a corrosion protection coating for hardenable steel sheets and corrosion protection layer for hardenable steel sheets

The invention relates to a method for producing a corrosion protection coating for hardenable steel sheets and a corrosion protection layer for hardenable steel sheets.

For the hardening of steel sheets or the production of sheet steel components made of sheet steel, which are hardened, and in particular ^¬ special car body components, there are currently two common Ver ^¬ drive.

Both methods have in common that a steel strip is produced from a steel material by hot rolling, and typically also subsequent cold ^¬ rollers and the steel strip is subsequently galvanized ^¬ ßend continuously. Driving the usual delay inkungsver- here is the hot-dip galvanizing, in which the steel strip is passed through a trough of liquid zinc, the liquid zinc adheres to the steel, the galvanized steel strip übli ^¬ cherweise is supported vertically from the trough and subsequently ^¬ ßend excess zinc stripped with scraper nozzles and the belt is then optionally subjected to a heat treatment. The galvanized steel strip produced in this way is then usually delivered in coils, ie wound up.

To create now from this steel strip hardened steel sheet metal parts are punched out of the steel strip boards of desired size and these boards then processed on two under ^¬ schiedliche species.

In a first method, the boards are formed in a conventional manner in a multi-stage process and in particular special deep-drawn until the component is molded in its final appearance. Here, however, the component is usually formed in all three spatial directions about 2% klei ^¬ ner to a subsequent thermal expansion to take into ^¬ into account. Subsequently, this sheet metal component is heated to a tempering temperature, ie a temperature above AC _3, and optionally held until the steel material is present in the austenitic phase. Subsequently, the heated sheet steel component is transferred to a mold hardening tool and held in the mold hardening tool, in which the heated steel ^¬ sheet metal component is usually used form-fitting, pressed by a die and a male, but not substantially reshaped. By the concerns of female and male molds, which can also be cooled, the steel ^¬ part is cooled at a rate above the critical Härtege ^¬ speed, resulting in a transformation of the austenite substantially to martensite and high hardness of the component is obtained.

In a second known method, the board is heated directly to a necessary for curing temperature above AC ₃ ^¬ and optionally held and then shaped in a mold consisting of male and female parts in a single stage ^¬ gen stroke and at the same time by the abutment of the tool on the workpiece so quickly cooled that the above skiz ^¬ ed curing occurs. This procedure is press hardening ge ^¬ Nannt.

The hot stamping is superior to the press hardening with regard to the possible geometries of a component, as in a multistage ^¬ gen forming process complicated or complex three-dimensional shapes can be achieved with only relatively simple geometries can be generated during the stage reshaping press hardening. However, the end result of both processes is a hardened sheet steel component.

Common materials for this steel components are so-called ^¬ boron manganese steels, in particular of this on ^¬ th wide spread 22MnB5.

It is known that may occur to the effect in press hardening process problems, particularly that liquid zinc is received with the existing in the steel material of austenite at high tempera ^¬ ren interactions which are not yet fully explained, but lead to the formation in the highly deformed areas cracks , This phenomenon is referred to as so-called "liquid metal embrittlement".

Attempts have been made to this phenomenon characterized entgegenzu ^¬ occur that conversion delayed steel grades used ^¬ to which are austenitized at a high temperature, then between cooled and reach through this intermediate ^¬ cool temperatures which are below the melting temperature of the zinc phases in the coating, and only then perform the forming. By converting delay the iron is still, even at these relatively low temperatures prior austenite, so that a reliable From ^¬ schreckhärtung can be achieved.

From DE 10 2010 030 465 Al a method for producing a z coating with a corrosion protection provided and formed from a high-strength steel sheet material formed sheet metal part is known. This method comprises the steps of shaping a starting sheet material to a sheet provided ^¬ molding, formation of the Korrosionsschut zbeschichtung by electrolytic application of a zinc-nickel coating to the sheet metal part, wherein at the beginning of the coating process First, a thin nickel layer is deposited, which further prevents hydrogen embrittlement of the steel sheet material. Further, a hot-molded and in particular ^¬ sondere press hardened sheet metal formed part made of a high-strength steel sheet material with an electrolytically applied zinc-nickel coating is known therefrom. The purpose of this is to provide the nickel layer as a barrier against ty ^¬ pisch enough, in the steel sheet material brought into the electrolytic coating is hydrogen.

EP 2 290 133 B1 discloses a method for producing a steel component provided with a metallic coating that protects against corrosion, and the steel component itself. Here ^¬ with a practically simple to carry out method to be created, which allows comparably little effort to produce a steel component which is provided with a well-haf ^¬ Tenden and safely protected from corrosion metallic coating, since it is indicated that zinc coatings on the Steel sheet types do not adhere well to hot press hardening. Furthermore, known coatings by oxidation of the surface should have a poor paint adhesion. According to this document, the applied corrosion protection layer should be an electrolytically brought to ^¬ γ-ZnNi phase, which is to tolerate then made heating operations well for the purpose of austenitization.

EP 0 364 596 B1 relates to a process for the production of zinc-nickel alloy-coated thin sheets with good compression molding properties, wherein the formability of such sheets is to be improved by a zinc-nickel alloy coating. The layer is to be deposited with about 30 g / m ² and a nickel content of 12.5%. The object of the invention is to provide a method for producing hardened sheet steel components.

The object is achieved by a method having the features of claim 1.

Advantageous developments are characterized in the subclaims.

It is a further object of the invention to provide a corrosion protective layer for ^¬ curable steel sheets, which decreases the liquid metal embritt- lement in good cathodic corrosion protection or even prevented.

The object is achieved with a corrosion protection layer having the features of claim 11.

Advantageous developments are characterized in dependent claims.

According to the invention, an at least two-layer corrosion ^¬ protective layer is formed on a steel sheet, whereby this ent ^¬ neither a very thin nickel layer of 1 pm is electrolytically deposited on the steel and then a zinc layer ^¬ also electrodeposited on the nickel layer abge ^¬ secreted is or thin Nickel layer is formed on the steel sheet via an electro ^¬ lytic deposition and then a zinc layer is applied via hot dip galvanizing. A further possibility is to apply to a normal hot-dip ^¬ zinktes steel strip via a corresponding after-treatment (coater) a nickel-containing layer. The nickel layer according to the invention has about 1 pm thickness, when they will be ^¬ introduced via electrolytic deposition as the first layer.

When a galvanized zinc layer is post-treated, the outer nickel-containing layer is about 250 nm to 700 nm thick.

According to the invention, it has surprisingly been found that in the coating according to the invention or the layer structure according to the invention the nickel in no form forms a barrier against the ingress of liquid zinc to the steel, but rather the nickel reacts very quickly with the zinc and also with iron. that the melting point of the entire corrosion ^¬ protection layer increases sharply, since instead of zinc-iron Γ-phases zinc-nickel-iron phases are increasingly formed, which have a much higher melting point. Hereby is achieved that at the temperatures at which hot formed ^¬ and is quench, no liquid phases are ^¬ that may interact with the austenite. This is also the reason why according to the invention, an external applied nickel layer in a similar way, where ^¬ at the nickel, which abgeschie ^¬ is the at the outermost surface, ^¬ diffuses so fast in the corrosion protective layer in that the increase of the melting point sicherge ^¬ represents is.

According to the invention, instead of nickel, or layers on the basis of nickel, other elements forming with Zn or Fe in ^¬ termetallisch baser phases onspotenzial have a higher oxidation as Zn, are as Cu, Co, Mn or Mo is used, since manganese, molybdenum, cobalt and copper achieve the same effects. "Based on" here means that these elements predominantly (> 50 wt .-%) are included, but other elements are present as alloying elements. Both nickel and cobalt as well as manganese or copper do not act as a physical barrier against the diffusion of zinc and iron, but are dissolved and incorporated in the molten zinc and zinc-iron phases. In the case of a previously applied nickel layer and subsequent hot-dip galvanizing, the nickel is at least already dissolved by the zinc melt during galvanizing.

In a standard annealing for the purpose of austenitizing and subsequent forming could be found that forms a similar phase structure of the layer as in pure hot-dip galvanized layers (phs-Ultraform), but this phase structure is zinc-rich or has a greater proportion of Γ-phases. That these phases are more zinc-rich, is advantageous for the cathodic corrosion protection performance of the layer.

This is further supported by the fact that a very rich zinc ^¬ near-surface layer is formed, is not observed in the Standardglühung without nickel intermediate layer, the verzinkungsschichten in conventional fire.

The positive effect of the nickel in the layer or as a sepa rat ^¬ applied electrolytic layer results in the loading ^¬ trachtung bending samples. The formation of cracks by the liquid metal embrittlement is impressively reduced.

The invention is exemplified erläu ^¬ tert reference to a drawing. It shows:

Figure 1: processing a light microscopic etched Schliffaufnähme ei ^¬ nes steel sheet with the inventive coating, which on a 1 pm thick nickel intermediate Layer a hot dip galvanized layer wur ^¬ de;

Figure 2: the layer of Figure 1 in an enlarged view.

Figure 3: a layer of Figure 1, wherein by EDX element mapping the elements iron, zinc, nickel and aluminum are shown in their distribution at a 1 pm thick applied nickel intermediate layer.

FIG. 4 shows a micrograph of the coating with a nickel layer 0.5 μm thick and a zinc coating 10 μm thick annealed at 800 ° C .;

FIG. 5 shows the layer according to FIG. 4 with a nickel layer 1 pm thick;

Figure 6: a coating according to the invention after annealing, a holding time, a transfer time and an on ^¬ closing cooling for press hardening;

FIG. 7 shows an X-ray micrograph of a corrosion protection layer according to the invention after austenitizing annealing at 870 ° C.;

FIG. 8 shows the layer according to FIG. 7 with the distribution of the iron;

FIG. 9 shows the layer according to FIG. 7 with the distribution of the zinc;

. 10 shows the layer of Figure 7 with the distribution of nickel, wherein nickel as a preparation aid of a support layer ^¬ is applied to the surface; FIG. 11 shows the layer according to FIG. 7 with the distribution of the aluminum;

FIG. 12 shows the layer according to FIG. 7 with the distribution of manganese;

FIG. 13 shows a coating according to the invention after austenitizing and quenching with an indicated EDX scan line;

FIG. 14 shows the coating according to FIG. 13 with the scan profile for the elements iron, nickel and zinc;

FIG. 15: four V samples with a bending radius of 1.5 mm.

Divide the process of the invention for generating Stahlblechbau ^¬ may be either a press hardening method or a form hardening process be, that is, a method in which a steel sheet member is heated and is then schreck cured in a mold from ^¬ (hot stamping), or a method in which a board stage is reformed and quench hardened (press hardening).

According to the invention, a boron-manganese steel is used as the steel material for press-hardening or mold-hardening, in which, with regard to the transformation of the austenite into other phases, the transformation can shift into deeper regions and martensite is formed.

As a transformation retarder in such steels, ie as an element which shifts the phase transformation of austenite to Mar ^¬ tensit to lower temperatures, in particular the alloying elements boron, manganese, carbon and optionally chromium and molybdenum are present.

Steels of the general alloy composition are suitable for the invention (all figures in percent by weight):

Carbon (C) 0 08-0.6

Manganese (Mn) 0.8-3.0

Aluminum (AI) 0, 01-0, 07

Silicon (Si) 0, 01-0.5

Chromium (Cr) 0.02-0.6

Titanium (Ti) 0, 01-0, 08

Nitrogen (N) <0.02

Boron (B) 0.002-0.02

Phosphorus (P) <0.01

Sulfur (S) <0.01

Molybdenum (Mo) <1

Remaining iron and impurities caused by melting.

In particular, steel assemblies have proved to be suitable as follows (all figures in weight percent):

Carbon (C) 0, 08-0.34

Manganese (Mn) 1, 00-3, 00

Aluminum (AI) 0, 03-0, 06

Silicon (Si) 0, 01-0,20

Chromium (Cr) 0.02-0.3

Titanium (Ti) 0, 03-0, 04

Nitrogen (N) <0.007

Boron (B) 0.002-0.006

Phosphorus (P) <0.01

Sulfur (S) <0.01

Molybdenum (Mo) <1

Remaining iron and impurities caused by melting. Thus, in particular, the conventional steels 22MnB5 or 20MnB8 are suitable.

By adjusting the alloying elements acting as a transformation retarder, a quench hardening, ie the ra ^¬ cal cooling with a cooling rate above the critical cure speed, even at 780 ° C is reached safely. This means that in this case below the peritectic system of the zinc-iron system is used, ie only below the peritectic mechanical stresses are applied. This further means that at the moment are applied in the mechanical stresses, no FLÜS ^¬ sigen zinc phases are left, which may come into contact with austenite.

A corrosion protection layer of the invention is an at least two layers ^¬ applied corrosion protective layer, wherein at least a nickel layer and a zinc layer are applied to a substrate made of a hardenable steel material. Instead of a nickel layer and a manganese or Kup ^¬ ferschicht can be applied.

Here, the nickel, copper or manganese layer preference ^¬ example is applied electrolytically. The zinc coating can be applied elekt ^¬ rolytisch or a hot-dip process.

In principle, it is possible to first the nickel layer and ^¬ closing apply a zinc layer, wherein the nachträg ^¬ Lich applied zinc layer is applied electrolytically or by hot dipping. A further possibility is to apply the zinc layer as the first layer electrolytically or hot-dip process and then a nickel layer thereon applied on the outermost surface, and more particularly elekt ^¬ rolytisch deposit.

Is spoken of nickel, hereby other ele ^¬ ments are meant to form Zn or Fe intermetallic phases baser and a higher oxidation potential than have Zn, as Cu, Co, Mn or Mo.

The element nickel is hereby also used for ^copper and manganese.

Surprisingly, it has been found that corresponding spre ^¬ accordingly applied metallic layers obviously intervene in the Pha ^¬ senaufbau a corrosion protection layer, but do not constitute a diffusion barrier itself. He is therefore the ^¬-making effective even when the thin nickel, copper o the manganese layer on a hot-galvanizing up ^¬ is introduced.

FIG. 1 shows a light-microscopic etched section of the layer according to the invention on a steel substrate. In Fig. 2, this is once again enlarged represents ^¬ .

In this layer, a 1 pm thick Nickelzwi ^¬ rule layer is first applied to the steel substrate and subsequently hot-dip galvanized ^¬ ßend, wherein the nickel was ^¬ interlayer dissolved in the zinc bath in the hot dip galvanizing.

When such a layer is measured with an EDX element distribution, it can be seen in FIG. 3 that an iron equivalent Distribution in the area of the steel is present, wherein at the boundary layer to the layers attached thereto, the iron content decreases. The distribution of zinc shows that the zinc content increases at the boundary to higher layers.

With respect to the nickel we can see that there must be a Gleichvertei ^¬ development within the layer, since no clear farbli ^¬ che statement with respect to the nickel present. The same applies to aluminum, which is included in the zinc coating for hot dip galvanizing.

In Figs. 4 and 5 each layers are juxtaposed, in which once the nickel intermediate layer has a thickness of 0.5 pm (Fig. 4) and once a layer thickness of 1 pm (Fig. 5) has ^¬ te. On each of these a hot-dip galvanized layer of 10 pm is deposited. Both layer samples were then heated to 800 ° C. The topmost light coat does not belong to the anticorrosive layers, it is a preparation auxiliary layer of nickel, which was applied before the sample preparation, ie after heating and cooling.

In the case of coatings according to the invention, a two-phase structure with a light phase which is penetrated by dark areas forms on the surface of the steel substrate (FIG. 6). This was annealed at 870 ° C in a 1 pm thick nickel intermediate layer, then 45 s was abgegewar ^¬ tet added to a transfer time of 5 s and then a cooling in a press.

A layer according to FIG. 6 was measured with an EDX element distribution, a nickel support layer also being present on the sample as a preparation aid. The ^{Schichtaus ¬ section} that was measured, is shown in Fig. 7. In the distribution of iron (Fig. 8), it can be seen that rela tive ^¬ little iron is present in the light phase while the dark phase exhibiting significant levels of iron.

In zinc, shows that this is highly enriched in the light phase while it is present in much lower concentrations in the dark areas, so that obviously an iron-rich phase as nodules or roundish Anrei ^¬ assurance is present in a zinc matrix.

The nickel (Figure 10) is still very poorly visible in the bright zinc matrix, but is apparently absent in the iron-rich nodules, while aluminum (Figure 11) is relatively uniform throughout the layer, albeit with accumulations in the zinc layer iron-rich phases.

Manganese, which is present in the base steel material, is scarcely present in the entire layer and can only be detected in the substrate.

In a comparable layer, the element distribution was determined in depth with a so-called EDX line scan (FIG. 13). Here, the scan already begins in the nickel support ^¬ layer and goes deep into the steel base material.

With a coating, which was annealed at 800 ° C, had 5 s transfer time and was then cooled press, results, as is shown in Fig. 14, a corresponding distri ^¬ development of the elements. The nickel peak is initially almost at 100%, which is because the scan starts in the nickel ^¬ preparation-layer. Subsequently, the Nickelgeh drops ^¬ old, where it is seen that in the dark iron-rich zones, the nickel content is significantly lower than in the bright zinc-rich phases. Accordingly, starting from the outer ßeren surface of the iron content is very low and is about 10% and increases in the dark iron-rich phase to interpreting ^¬ Lich, to then reach its maximum in the steel matrix. The content of iron is inversely related to the zinc content, which was to be expected according to the two-phase formation.

From an originally existing nickel layer is no longer visible in the phase structure.

The positive effect of nickel in the layer can be seen in bend samples having a radius of 1.5 mm (Figure 15).

While with a nickel interlayer of only 0.5 pm (with the complete dissolution of the nickel in the corrosion protection coating, the thickness of the nickel layer has an effect only on the amount of nickel in the layer). At 0.5 pm nickel and 10 pm hot-dip galvanized layer, this results in a crack pattern at 870 ° C. annealing temperature, 45 s holding time, 6 s transfer time and corresponding cooling in the press, as can be seen in the two left-hand illustrations in FIG ,

In contrast, with a 1 pm thick nickel layer and otherwise identical conditions, a considerably finer crack pattern is achieved (FIG. 15, the two right-hand representations).

The invention thus makes it possible to take an additional Ni ^¬ ckelschicht an impact on the corrosion protection layer ba ^¬ sierend on zinc, in the way that this layer forms obviously faster solid phases upon cooling, which then during the shaping does not match the austenite of Stahlsub ^¬ strats react. In particular, in the zinc-rich bright phases of the coating, more nickel dissolves than in the dark iron-rich phases, which by themselves have a higher melting point.

Compared with a zinc-nickel layer deposited uniformly via electrolysis, the invention has the advantage that it permits a mixed application in electrolytic and melt-dip coating processes. Furthermore, the nickel layer can be applied to conventional, already galvanized sheets readily which purpose both elekt ^¬ rolytische coatings can be applied as well as other coating methods such. B. roll application, ie, a roll coating method, such as a coil coating method, in which a nickel-containing layer is applied with egg ^¬ ner thickness of 250 nm to 700 nm.

Claims

claims

1. A method for producing hardened sheet steel components, wherein on a strip of a quench-hardenable steel alloy as Korrosionsschut zbeschichtung at least two metal layers are successively deposited on the steel substrate, wherein the one metal layer is a layer of zinc or based on zinc and the other layer ei ^¬ ne Is a layer of a metal which forms intermetallic with Zn or Fe inter ^¬ metallic phases and a higher oxidation potential than Zn, namely Ni, Cu, Co, Mn or Mo, or a layer based on these metals is and wherein steels of general alloy composition, in each case in percent by weight:

Carbon (C) 0 08-0.6

Manganese (Mn) 0, 8-3,0

Aluminum (AI) 0, 01-0, 07

Silicon (Si) 0, 01-0.5

Chromium (Cr) 0, 02-0.6

Titanium (Ti) 0, 01-0, 08

Nitrogen (N) <0.02

Boron (B) 0, 002-0.02

Phosphorus (P) <0.01

Sulfur (S) <0.01

Molybdenum (Mo) <1

Balance iron and incidental impurities be used, where blanks are punched out of the with the Korrosionsschut ZBE ^¬ coating is provided tape and the boards either

- heated to a temperature> AC ₃ and optionally held and then in a Presshärtewerk- be formed and quench hardened to produce the sheet steel component, or

- The boards are cold formed into a sheet steel component and then the steel sheet component is heated to a temperature> AC ₃ and is quench hardened in a mold hardness ^¬ tool.

A method according to claim 1, characterized in that al steel material, a material having the following alloy additions ^¬ composition, respectively, the percentage of weight ver ^¬ turns is:

Carbon (C) 0, 08-0.34

Manganese (Mn) 1, 00-3, 00

Aluminum (AI) 0, 03-0, 06

Silicon (Si) 0, 01-0,20

Chromium (Cr) 0, 02-0.3

Titanium (Ti) 0, 03-0, 04

Nitrogen (N) <0.007

Boron (B) 0, 002-0,006

Phosphorus (P) <0.01

Sulfur (S) <0.01

Molybdenum (Mo) <1

Remaining iron and impurities caused by melting.

A method according to claim 1 or 2, characterized in that the layer of zinc or based on zinc electro ^¬ lytic or via a ^hot dip method is applied.

4. The method according to claim 1 to 3, characterized in that the nickel, copper or manganese layer electrolytically or via a roll coating process, for example a coil coating process.

5. The method according to any one of the preceding claims, characterized in that the nickel, copper or manganese ^¬ layer in a thickness of 0.5 pm to 2 pm in electrolytic ^¬ shear deposition or 250 nm to 700 nm in Walzenappli- ornamentation in particular Coil coating process is applied.

6. The method according to any one of the preceding claims, characterized in that the zinc layer or layer based on zinc with a thickness of 6 pm to 30 pm is deposited.

7. The method according to any one of the preceding claims, characterized in that the layer of nickel, copper or manganese is first deposited on the steel substrate and thereon the zinc layer or coating based on zinc is deposited.

8. The method according to any one of the preceding claims, characterized in that the coating of zinc or Ba ^¬ sis of zinc on the layer of nickel, copper or manganese is applied electrolytically or by hot-dip galvanizing.

9. The method according to any one of the preceding claims, characterized in that first the layer of zinc or on the basis of zinc electrolytically or by hot dip coating process on the steel substrate is applied and then the nickel layer electrolytically on the zinc ^¬ layer or with a roller application method, eg , Coil coating process, is applied to the zinc layer.

10. The method according to any one of the preceding claims, characterized in that the layer sequence between nickel, copper and manganese on the one hand and zinc or based on zinc on the other hand repeatedly applied.

11 corrosion protection layer for use in a method according to one of claims 1 to 10, wherein the corrosion ^¬ protective layer has at least two layers, wherein a layer of nickel, copper or manganese is present and on or below a layer of zinc or based on zinc is available.

12. corrosion protection layer according to claim 11, characterized in that the layer of zinc or based on zinc is deposited electrolytically or via a hot dip process.

13. corrosion protection layer according to claim 11 or 12, characterized in that the nickel, copper or manganese ^¬ layer is applied electrolytically or via a roller application method, for example, coil coating process.

14. corrosion protection layer according to one of claims 11 to 13, characterized in that nickel, copper or manganese ^¬ layer has a thickness of 0.5 pm to 2 pm with electrolytic deposition or 250 nm to 700 nm in a roll coating method, in particular coil Coating process, owns.

15. corrosion protection layer according to one of claims 11 to 14, characterized in that the zinc layer or the Zinc-based layer has a thickness of 6 pm to 30 pm.

16. Corrosion protection layer according to one of claims 11 to 15, characterized in that the layer of nickel, copper or manganese is arranged on the steel substrate and dar ^¬ on the zinc layer or the coating based on zinc.

A corrosion protection layer according to any one of claims 11 to 16, characterized in that a zinc layer or coating based on zinc, which has been deposited electrolytically or by hot dip coating, is applied on the steel substrate, and the nickel layer is disposed on the zinc layer, the Ni ^¬ ckelschicht electrolytically or by a Walzenauftrags ^¬ method, in particular coil coating process is applied.

18 corrosion protection layer according to one of claims 11 to 17, characterized in that on the steel substrate, a multiple sequence of layers nickel, copper and manganese on the one hand and zinc or layers based on zinc ande ^¬ hand, is present.