WO2015090621A1 - Steel substrate provided with corrosion resistant coating with high melting temperature - Google Patents

Steel substrate provided with corrosion resistant coating with high melting temperature Download PDF

Info

Publication number
WO2015090621A1
WO2015090621A1 PCT/EP2014/025025 EP2014025025W WO2015090621A1 WO 2015090621 A1 WO2015090621 A1 WO 2015090621A1 EP 2014025025 W EP2014025025 W EP 2014025025W WO 2015090621 A1 WO2015090621 A1 WO 2015090621A1
Authority
WO
WIPO (PCT)
Prior art keywords
coating
steel substrate
layer
substrate according
content
Prior art date
Application number
PCT/EP2014/025025
Other languages
French (fr)
Inventor
Edzo ZOESTBERGEN
Jörgen VAN DE LANGKRUIS
Robert Bleeker
Original Assignee
Tata Steel Nederland Technology B.V.
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Application filed by Tata Steel Nederland Technology B.V. filed Critical Tata Steel Nederland Technology B.V.
Priority to KR1020167017071A priority Critical patent/KR20160099588A/en
Priority to EP14816137.5A priority patent/EP3084032B1/en
Publication of WO2015090621A1 publication Critical patent/WO2015090621A1/en

Links

Classifications

    • C—CHEMISTRY; METALLURGY
    • C23—COATING METALLIC MATERIAL; COATING MATERIAL WITH METALLIC MATERIAL; CHEMICAL SURFACE TREATMENT; DIFFUSION TREATMENT OF METALLIC MATERIAL; COATING BY VACUUM EVAPORATION, BY SPUTTERING, BY ION IMPLANTATION OR BY CHEMICAL VAPOUR DEPOSITION, IN GENERAL; INHIBITING CORROSION OF METALLIC MATERIAL OR INCRUSTATION IN GENERAL
    • C23C—COATING METALLIC MATERIAL; COATING MATERIAL WITH METALLIC MATERIAL; SURFACE TREATMENT OF METALLIC MATERIAL BY DIFFUSION INTO THE SURFACE, BY CHEMICAL CONVERSION OR SUBSTITUTION; COATING BY VACUUM EVAPORATION, BY SPUTTERING, BY ION IMPLANTATION OR BY CHEMICAL VAPOUR DEPOSITION, IN GENERAL
    • C23C14/00—Coating by vacuum evaporation, by sputtering or by ion implantation of the coating forming material
    • C23C14/06—Coating by vacuum evaporation, by sputtering or by ion implantation of the coating forming material characterised by the coating material
    • C23C14/14—Metallic material, boron or silicon
    • C23C14/16—Metallic material, boron or silicon on metallic substrates or on substrates of boron or silicon
    • C23C14/165—Metallic material, boron or silicon on metallic substrates or on substrates of boron or silicon by cathodic sputtering
    • C—CHEMISTRY; METALLURGY
    • C23—COATING METALLIC MATERIAL; COATING MATERIAL WITH METALLIC MATERIAL; CHEMICAL SURFACE TREATMENT; DIFFUSION TREATMENT OF METALLIC MATERIAL; COATING BY VACUUM EVAPORATION, BY SPUTTERING, BY ION IMPLANTATION OR BY CHEMICAL VAPOUR DEPOSITION, IN GENERAL; INHIBITING CORROSION OF METALLIC MATERIAL OR INCRUSTATION IN GENERAL
    • C23C—COATING METALLIC MATERIAL; COATING MATERIAL WITH METALLIC MATERIAL; SURFACE TREATMENT OF METALLIC MATERIAL BY DIFFUSION INTO THE SURFACE, BY CHEMICAL CONVERSION OR SUBSTITUTION; COATING BY VACUUM EVAPORATION, BY SPUTTERING, BY ION IMPLANTATION OR BY CHEMICAL VAPOUR DEPOSITION, IN GENERAL
    • C23C10/00—Solid state diffusion of only metal elements or silicon into metallic material surfaces
    • C23C10/28—Solid state diffusion of only metal elements or silicon into metallic material surfaces using solids, e.g. powders, pastes
    • C—CHEMISTRY; METALLURGY
    • C23—COATING METALLIC MATERIAL; COATING MATERIAL WITH METALLIC MATERIAL; CHEMICAL SURFACE TREATMENT; DIFFUSION TREATMENT OF METALLIC MATERIAL; COATING BY VACUUM EVAPORATION, BY SPUTTERING, BY ION IMPLANTATION OR BY CHEMICAL VAPOUR DEPOSITION, IN GENERAL; INHIBITING CORROSION OF METALLIC MATERIAL OR INCRUSTATION IN GENERAL
    • C23C—COATING METALLIC MATERIAL; COATING MATERIAL WITH METALLIC MATERIAL; SURFACE TREATMENT OF METALLIC MATERIAL BY DIFFUSION INTO THE SURFACE, BY CHEMICAL CONVERSION OR SUBSTITUTION; COATING BY VACUUM EVAPORATION, BY SPUTTERING, BY ION IMPLANTATION OR BY CHEMICAL VAPOUR DEPOSITION, IN GENERAL
    • C23C14/00—Coating by vacuum evaporation, by sputtering or by ion implantation of the coating forming material
    • C23C14/06—Coating by vacuum evaporation, by sputtering or by ion implantation of the coating forming material characterised by the coating material
    • C23C14/08—Oxides
    • C—CHEMISTRY; METALLURGY
    • C23—COATING METALLIC MATERIAL; COATING MATERIAL WITH METALLIC MATERIAL; CHEMICAL SURFACE TREATMENT; DIFFUSION TREATMENT OF METALLIC MATERIAL; COATING BY VACUUM EVAPORATION, BY SPUTTERING, BY ION IMPLANTATION OR BY CHEMICAL VAPOUR DEPOSITION, IN GENERAL; INHIBITING CORROSION OF METALLIC MATERIAL OR INCRUSTATION IN GENERAL
    • C23C—COATING METALLIC MATERIAL; COATING MATERIAL WITH METALLIC MATERIAL; SURFACE TREATMENT OF METALLIC MATERIAL BY DIFFUSION INTO THE SURFACE, BY CHEMICAL CONVERSION OR SUBSTITUTION; COATING BY VACUUM EVAPORATION, BY SPUTTERING, BY ION IMPLANTATION OR BY CHEMICAL VAPOUR DEPOSITION, IN GENERAL
    • C23C14/00—Coating by vacuum evaporation, by sputtering or by ion implantation of the coating forming material
    • C23C14/22—Coating by vacuum evaporation, by sputtering or by ion implantation of the coating forming material characterised by the process of coating
    • C23C14/34—Sputtering
    • C23C14/35—Sputtering by application of a magnetic field, e.g. magnetron sputtering
    • C—CHEMISTRY; METALLURGY
    • C23—COATING METALLIC MATERIAL; COATING MATERIAL WITH METALLIC MATERIAL; CHEMICAL SURFACE TREATMENT; DIFFUSION TREATMENT OF METALLIC MATERIAL; COATING BY VACUUM EVAPORATION, BY SPUTTERING, BY ION IMPLANTATION OR BY CHEMICAL VAPOUR DEPOSITION, IN GENERAL; INHIBITING CORROSION OF METALLIC MATERIAL OR INCRUSTATION IN GENERAL
    • C23C—COATING METALLIC MATERIAL; COATING MATERIAL WITH METALLIC MATERIAL; SURFACE TREATMENT OF METALLIC MATERIAL BY DIFFUSION INTO THE SURFACE, BY CHEMICAL CONVERSION OR SUBSTITUTION; COATING BY VACUUM EVAPORATION, BY SPUTTERING, BY ION IMPLANTATION OR BY CHEMICAL VAPOUR DEPOSITION, IN GENERAL
    • C23C16/00—Chemical coating by decomposition of gaseous compounds, without leaving reaction products of surface material in the coating, i.e. chemical vapour deposition [CVD] processes
    • C23C16/06—Chemical coating by decomposition of gaseous compounds, without leaving reaction products of surface material in the coating, i.e. chemical vapour deposition [CVD] processes characterised by the deposition of metallic material
    • C—CHEMISTRY; METALLURGY
    • C23—COATING METALLIC MATERIAL; COATING MATERIAL WITH METALLIC MATERIAL; CHEMICAL SURFACE TREATMENT; DIFFUSION TREATMENT OF METALLIC MATERIAL; COATING BY VACUUM EVAPORATION, BY SPUTTERING, BY ION IMPLANTATION OR BY CHEMICAL VAPOUR DEPOSITION, IN GENERAL; INHIBITING CORROSION OF METALLIC MATERIAL OR INCRUSTATION IN GENERAL
    • C23C—COATING METALLIC MATERIAL; COATING MATERIAL WITH METALLIC MATERIAL; SURFACE TREATMENT OF METALLIC MATERIAL BY DIFFUSION INTO THE SURFACE, BY CHEMICAL CONVERSION OR SUBSTITUTION; COATING BY VACUUM EVAPORATION, BY SPUTTERING, BY ION IMPLANTATION OR BY CHEMICAL VAPOUR DEPOSITION, IN GENERAL
    • C23C28/00—Coating for obtaining at least two superposed coatings either by methods not provided for in a single one of groups C23C2/00 - C23C26/00 or by combinations of methods provided for in subclasses C23C and C25C or C25D
    • C23C28/30—Coatings combining at least one metallic layer and at least one inorganic non-metallic layer
    • C23C28/32—Coatings combining at least one metallic layer and at least one inorganic non-metallic layer including at least one pure metallic layer
    • C23C28/321—Coatings combining at least one metallic layer and at least one inorganic non-metallic layer including at least one pure metallic layer with at least one metal alloy layer
    • C—CHEMISTRY; METALLURGY
    • C23—COATING METALLIC MATERIAL; COATING MATERIAL WITH METALLIC MATERIAL; CHEMICAL SURFACE TREATMENT; DIFFUSION TREATMENT OF METALLIC MATERIAL; COATING BY VACUUM EVAPORATION, BY SPUTTERING, BY ION IMPLANTATION OR BY CHEMICAL VAPOUR DEPOSITION, IN GENERAL; INHIBITING CORROSION OF METALLIC MATERIAL OR INCRUSTATION IN GENERAL
    • C23C—COATING METALLIC MATERIAL; COATING MATERIAL WITH METALLIC MATERIAL; SURFACE TREATMENT OF METALLIC MATERIAL BY DIFFUSION INTO THE SURFACE, BY CHEMICAL CONVERSION OR SUBSTITUTION; COATING BY VACUUM EVAPORATION, BY SPUTTERING, BY ION IMPLANTATION OR BY CHEMICAL VAPOUR DEPOSITION, IN GENERAL
    • C23C28/00—Coating for obtaining at least two superposed coatings either by methods not provided for in a single one of groups C23C2/00 - C23C26/00 or by combinations of methods provided for in subclasses C23C and C25C or C25D
    • C23C28/30—Coatings combining at least one metallic layer and at least one inorganic non-metallic layer
    • C23C28/34—Coatings combining at least one metallic layer and at least one inorganic non-metallic layer including at least one inorganic non-metallic material layer, e.g. metal carbide, nitride, boride, silicide layer and their mixtures, enamels, phosphates and sulphates
    • C23C28/345—Coatings combining at least one metallic layer and at least one inorganic non-metallic layer including at least one inorganic non-metallic material layer, e.g. metal carbide, nitride, boride, silicide layer and their mixtures, enamels, phosphates and sulphates with at least one oxide layer
    • C—CHEMISTRY; METALLURGY
    • C25—ELECTROLYTIC OR ELECTROPHORETIC PROCESSES; APPARATUS THEREFOR
    • C25D—PROCESSES FOR THE ELECTROLYTIC OR ELECTROPHORETIC PRODUCTION OF COATINGS; ELECTROFORMING; APPARATUS THEREFOR
    • C25D5/00—Electroplating characterised by the process; Pretreatment or after-treatment of workpieces
    • C25D5/48—After-treatment of electroplated surfaces
    • C25D5/50—After-treatment of electroplated surfaces by heat-treatment
    • C—CHEMISTRY; METALLURGY
    • C25—ELECTROLYTIC OR ELECTROPHORETIC PROCESSES; APPARATUS THEREFOR
    • C25D—PROCESSES FOR THE ELECTROLYTIC OR ELECTROPHORETIC PRODUCTION OF COATINGS; ELECTROFORMING; APPARATUS THEREFOR
    • C25D3/00—Electroplating: Baths therefor
    • C25D3/02—Electroplating: Baths therefor from solutions
    • C25D3/56—Electroplating: Baths therefor from solutions of alloys
    • C25D3/565—Electroplating: Baths therefor from solutions of alloys containing more than 50% by weight of zinc

Definitions

  • the invention relates to a steel substrate provided with a corrosion resistant Zn- based coating wherein the coating has a high melting temperature.
  • High temperature processes are for instance forming operations like hot forming operations.
  • hot forming the material is preheated to a temperature typically in a range of about 880 - 930°C.
  • the actual forming temperature should be high enough to allow the required local deformations in the part without tearing, but can be significantly lower than the preheat temperature to restrict the occurrence of micro-crack formation.
  • the blank temperature should be at least 500°C when placed in the hot forming press, more preferably 600°C, and still more preferably 650°C.
  • High temperature environments are for instance exhaust systems and flue tubes or housings for engines and the like.
  • the Al-Si coatings perform well in hot pressing operations, but the disadvantage of these Al-Si coatings is that only a barrier corrosion protection is provided, not a cathodic corrosion protection such as provided by Zn-based coatings.
  • one or more of the objectives of the invention are realized by providing a steel substrate provided with a Zn-based corrosion resistant coating, wherein the Zn-based coating has a melting temperature above 600°C and wherein the Zn-based coating is a Zn-Mn coating with a Mn content of >19 wt%, a Zn-Sr coating with a Sr content of > 9 wt% or a Zn-Ca coating with a Ca content of > 5 wt%.
  • This temperature is below typical processing temperatures in hot-forming operations, but as disclosed in WO2012097976A1 and mentioned above hot forming may take place at lower temperatures such as 600 °C, provided that the plastic behaviour of the blank allows the required deformations.
  • the Mn, Sr or Ca content in the Zn-based coating decreases Zn-diffusion to a rate lower than with a pure zinc coating at temperatures below the coating melting temperature, and realizes the higher melting temperatures of Zn-based coatings, thus controlling the risks for micro-crack formation and liquid metal embrittlement respectively.
  • the Mn-content in the Zn-Mn coating is in the range of 19 - 30 wt%.
  • the addition of Mn is very effective.
  • the liquidus temperature of the coating for the lower end of this range is 700°C or above and the risk for liquid metal embrittlement is reduced.
  • the Mn-content should not be increased above 60 wt% in order to still have enough Zn-content in the coating.
  • the lower limit of the Mn-content is not lower than 19 wt% which means that the liquidus temperature of the coating is above 700°C. With such a Mn-content the coating is suitable for hot forming operations without the risk of liquid metal embrittlement.
  • the solidus temperature of the coating is above 950°C, which makes the coating suitable for preheating- and forming operations at 850-950°C, without risk of liquid metal embrittlement.
  • the cathodic corrosion protection of the coating is noticeably less than with the preferred Mn range of 19 - 30 wt%.
  • the Sr-content in the Zn-Sr coating is in the range of 9 - 14 wt% and more preferably in the range of 9 - 1 1 wt%. With the Sr-content in the latter range the melting temperature of the Zn-Sr coating is in the order of 830°C. In addition to the high melting temperature a further advantage is that the Zn-content of the coating is high resulting in that sufficient Zn is available for cathodic corrosion protection.
  • the Ca- content in the Zn-Ca coating is in the range of 5 - 24 wt% and more preferably in the range of 5 - 8 wt%. With the Ca-content in the latter range the melting temperature is in the order of 725°C. In addition to the high melting temperature the coating has a high Zn-content resulting in that sufficient Zn is available for cathodic corrosion protection.
  • a diffusion barrier layer is provided between the substrate and the Zn-based coating layer.
  • a number of conductive oxides such as chromium oxide (Cr203), indium oxide (In02) and tin oxide (Sn02), along with conductive nitrides (for instance TiN), silicides (for instance MoSi 2 ), and borides can be used as diffusion barriers.
  • conductive nitrides for instance TiN
  • silicides for instance MoSi 2
  • borides can be used as diffusion barriers.
  • a Ni + Pd alloy could be used as a diffusion layer to prevent diffusion of zinc.
  • the melting temperature of these diffusion barrier layers are all above 1000°C.
  • These diffusion barrier layers can be applied by a number of different techniques including vapour deposition such as chemical vapour deposition, physical vapour deposition, sputtering and pyrolitic deposition.
  • the diffusion barrier layer is a tungsten or tungsten alloy layer which has a melting temperature well above 1000°C.
  • a tungsten or tungsten alloy layer will not react with Zn and will prevent diffusion of zinc into the substrate during preheating before hot forming. Diffusion of carbon from the substrate into the tungsten or tungsten alloy diffusion barrier layer may easily occur, but that will not hamper the working of the layer as a Zn-diffusion barrier layer. Depending on thickness of the barrier layer Zn diffusion will be prevented totally or at least to a large extent. Because of the high melting temperature of tungsten a barrier layer of this material is applied preferably by sputtering.
  • the advantage of deposition by sputtering is that it is a relatively easy deposition method to carry out. Because of the effectiveness of tungsten as a barrier layer, a relatively thin barrier layer will be sufficient, that is a thickness in the range of 2-50 nm will be sufficient.
  • the barrier layer can also be used in other Zn or Zn-based corrosion resistant coatings than the coatings according to the invention.
  • the tungsten barrier layer can be applied on a substrate, such as a steel strip, before the Zn or Zn-based coating is applied by hot dip galvanizing or any other coating method known in the art.
  • an evaporation barrier is provided on top of the Zn-based coating layer.
  • the high melting point of the Zn-based coating layers according to the invention aids to minimise the coating evaporation and maintain the cathodic corrosion protection by the coating.
  • an additional coating is provided on top of the Zn-based coating layer according the invention. This top coating layer does not only prevent evaporation but also reduces the oxidation behaviour of the Zn-based coating layer.
  • evaporation barrier is used this will also mean a barrier layer with which oxidation of the Zn-based coating layer is reduced as far as applicable.
  • an oxide-based top coating layer with a thickness in the range of 5-1000nm consisting of for instance chromium oxide (Cr203), indium oxide (In02) or tin oxide (Sn02). Also other oxide films may be possible.
  • the oxides produce a closed surface on top of the coating also when the Zn-based coating layer becomes liquid.
  • the oxide-based top layer is deposited either as:
  • ⁇ as a coating layer that will form an oxide when in contact with air.
  • a top coating layer of ⁇ 1 ⁇ 2 forms a continuously renewable aluminium oxide layer on the coating surface at high temperatures, for example during preheating in a hot forming process. This oxide helps to prevent the high-temperature degradation of the nitride.
  • the melting temperatures of the Zn-based coatings according to the invention are well above those of the commonly used standard Zn or Zn-based coatings makes a substrate with a Zn-based coatings according to the invention suitable for use in high temperature applications such as press-hardening operations.
  • the steel substrate is a steel suitable for press- hardening.
  • the steel substrate is a strip of boron steel.
  • the Zn-based coating is applied by means of vapour deposition for instance chemical vapour deposition (CVD) and physical vapour deposition (PVD).
  • the deposition by means of PVD allows for a very controlled deposition of the Zn-based coating layer to the required thickness within a narrow range of deviation. This means that the thickness of the Zn-based coating layer can be less than the thickness of such a layer when deposited by means of a hot-dip process.
  • a Zn-based coating applied by hot-dip coating will usually be in the order of ⁇ , whereas a Zn-based coating applied by PVD will be in the range of 2 - ⁇ and preferably in the range of 3 - 8 ⁇ . The more so if diffusion of Zn into the substrate is prevented by means of a barrier layer and evaporation and/or oxidation of constituents of the Zn-based coating layer by means of a top layer.
  • the diffusion barrier layer and evaporation/oxidation barrier layer are applied by means of physical vapour deposition which has the same advantages as described for the deposition of the Zn-based coating layer by means of physical vapour deposition.
  • Physical vapour deposition can be carried out using for instance magnetron sputtering.
  • the evaporation barrier layer can also be deposited using other deposition methods such as electroplating.
  • the produced ZnMn coated samples were heated in a Pananalytical X-Ray Diffractometer type Xpert Pro, equipped with a heating cell, in 3 minutes to 900°C, held at this temperature for 6 minutes and subsequently cooled to 400 °C in 1 minute and further to below 100°C within another 7 minutes.
  • two different gas atmospheres have been used: pure nitrogen or air.
  • the heating cycle is similar to that used in preheat cycles for hot forming processes for car parts.
  • Adding a diffusion barrier layer in between the substrate and the ZnMn layer and an evaporation barrier layer on top of the ZnMn layer will result in even better cathodic protection by keeping the ZnMn layer more intact during annealing and thus have more Zn and Mn available for cathodic protection in the end product.

Landscapes

  • Chemical & Material Sciences (AREA)
  • Chemical Kinetics & Catalysis (AREA)
  • Engineering & Computer Science (AREA)
  • Materials Engineering (AREA)
  • Metallurgy (AREA)
  • Organic Chemistry (AREA)
  • Mechanical Engineering (AREA)
  • Inorganic Chemistry (AREA)
  • Electrochemistry (AREA)
  • General Chemical & Material Sciences (AREA)
  • Other Surface Treatments For Metallic Materials (AREA)
  • Physical Vapour Deposition (AREA)

Abstract

The invention relates to a steel substrate provided with a Zn-based corrosion resistant coating, wherein the Zn-based coating has a melting temperature above 600°C which makes it suitable for forming operations at elevated temperatures.

Description

STEEL SUBSTRATE PROVIDED WITH CORROSION RESISTANT COATING WITH HIGH MELTING TEMPERATURE
Field of the invention
The invention relates to a steel substrate provided with a corrosion resistant Zn- based coating wherein the coating has a high melting temperature.
Background of the invention
In applications where a steel substrate provided with a corrosion resistant coating is subjected to high temperature processes or high temperature environments there are only a limited number of coatings that are suitable to use.
High temperature processes are for instance forming operations like hot forming operations. In hot forming the material is preheated to a temperature typically in a range of about 880 - 930°C. The actual forming temperature should be high enough to allow the required local deformations in the part without tearing, but can be significantly lower than the preheat temperature to restrict the occurrence of micro-crack formation. In WO20120979 it has been disclosed that the blank temperature should be at least 500°C when placed in the hot forming press, more preferably 600°C, and still more preferably 650°C.
High temperature environments are for instance exhaust systems and flue tubes or housings for engines and the like.
In hot forming operations of steel blanks, Al-Si coatings and Zn-based coatings are currently being used. In a hot forming operation a coated steel blank is first subjected to an austenization heat treatment after which the blank is transported to the press, formed and rapidly quenched.
The Al-Si coatings perform well in hot pressing operations, but the disadvantage of these Al-Si coatings is that only a barrier corrosion protection is provided, not a cathodic corrosion protection such as provided by Zn-based coatings.
However, with Zn-based coatings it is much more complicated to carry out hot forming operations because of zinc diffusion into the substrate, zinc evaporation, the forming of micro-cracks due to solid metal induced embrittlement, part rupture due to liquid metal embrittlement and oxide formation issues. These phenomena are related to the specific processing conditions.
At too high temperatures or too long holding times the zinc evaporation is such that the remaining zinc weight is too low for sufficient cathodic protection. Another problem is the diffusion of Zn into the steel substrate and although still a cathodic protection is obtained with the resulting diffusion layer this protection is far less than with a Zn-only coating layer on the substrate.
Penetration of liquid Zn-phases of a Zn-based coating between steel substrate grain boundaries might occur during hot pressing operation resulting in macro-cracking. This might even lead to complete failure of the final product due to liquid metal embrittlement.
Another problem with Zn-based coatings in hot pressing operations is the control of surface oxidation. The oxidised surfaces of the final product require a post cleaning process, which at present is standard practice and can be done with shot blasting. However, the forming of very thick oxide layers has a negative effect on the remaining Zn- weight and hence on the corrosion protection offered by the resulting coating.
Further problems may arise with the further processing of hot pressed products wherein the coating type and the presence of oxides may have a negative effect on weldability, adhesive bonding and paintability.
In order to reduce these problems as much as possible with the currently used Zn- based coatings in hot forming there is only a small temperature/time window available for hot pressing operations.
Objectives of the invention
It is an objective of the present invention to provide a substrate with a Zn-based corrosion resistant coating that is able to withstand high temperatures.
It is another objective of the present invention to provide a substrate with a Zn- based corrosion resistant coating that is suitable to be used in hot forming operations.
It is another objective of the present invention to provide a substrate with a Zn- based corrosion resistant coating with means to prevent diffusion of Zn into the substrate. It is another objective of the present invention to provide a substrate with a Zn- based corrosion resistant coating with means to prevent evaporation of the Zn-based coating.
It is still another objective of the present invention to provide a substrate with a Zn-based corrosion resistant coating with means to prevent oxidation of the Zn-based coating.
Description of the invention
According to a first aspect of the invention one or more of the objectives of the invention are realized by providing a steel substrate provided with a Zn-based corrosion resistant coating, wherein the Zn-based coating has a melting temperature above 600°C and wherein the Zn-based coating is a Zn-Mn coating with a Mn content of >19 wt%, a Zn-Sr coating with a Sr content of > 9 wt% or a Zn-Ca coating with a Ca content of > 5 wt%.
In these Zn-based coatings the balance is Zn and inevitable impurities.
This temperature is below typical processing temperatures in hot-forming operations, but as disclosed in WO2012097976A1 and mentioned above hot forming may take place at lower temperatures such as 600 °C, provided that the plastic behaviour of the blank allows the required deformations.
The Mn, Sr or Ca content in the Zn-based coating decreases Zn-diffusion to a rate lower than with a pure zinc coating at temperatures below the coating melting temperature, and realizes the higher melting temperatures of Zn-based coatings, thus controlling the risks for micro-crack formation and liquid metal embrittlement respectively.
According to a further aspect of the invention it is provided that the Mn-content in the Zn-Mn coating is in the range of 19 - 30 wt%. In realizing higher melting temperatures of a Zn-based coating the addition of Mn is very effective. With a Mn- content in the range of > 19 wt% the liquidus temperature of the coating for the lower end of this range is 700°C or above and the risk for liquid metal embrittlement is reduced. By increasing the Mn-content the liquidus temperature will also increase, but since the coating is to offer cathodic corrosion protection the Mn-content should not be increased above 60 wt% in order to still have enough Zn-content in the coating. Preferably the lower limit of the Mn-content is not lower than 19 wt% which means that the liquidus temperature of the coating is above 700°C. With such a Mn-content the coating is suitable for hot forming operations without the risk of liquid metal embrittlement.
If the Mn-content in the Zn-Mn coating is raised to 55 - 60 wt% the solidus temperature of the coating is above 950°C, which makes the coating suitable for preheating- and forming operations at 850-950°C, without risk of liquid metal embrittlement. However, at this Mn content the cathodic corrosion protection of the coating is noticeably less than with the preferred Mn range of 19 - 30 wt%.
To realize high enough temperatures in a Zn-Sr coating it is preferably provided that the Sr-content in the Zn-Sr coating is in the range of 9 - 14 wt% and more preferably in the range of 9 - 1 1 wt%. With the Sr-content in the latter range the melting temperature of the Zn-Sr coating is in the order of 830°C. In addition to the high melting temperature a further advantage is that the Zn-content of the coating is high resulting in that sufficient Zn is available for cathodic corrosion protection.
To realize high enough temperatures in a Zn-Ca coating it is provided that the Ca- content in the Zn-Ca coating is in the range of 5 - 24 wt% and more preferably in the range of 5 - 8 wt%. With the Ca-content in the latter range the melting temperature is in the order of 725°C. In addition to the high melting temperature the coating has a high Zn-content resulting in that sufficient Zn is available for cathodic corrosion protection.
According to a further aspect of the invention a diffusion barrier layer is provided between the substrate and the Zn-based coating layer. With the melting temperatures of the Zn-based coatings according to the invention diffusion of Zn into the substrate might easily occur when heated to an elevated temperature and in order to prevent Zn- diffusion a diffusion barrier layer is applied on the substrate.
A number of conductive oxides, such as chromium oxide (Cr203), indium oxide (In02) and tin oxide (Sn02), along with conductive nitrides (for instance TiN), silicides (for instance MoSi2), and borides can be used as diffusion barriers. Alternatively a Ni + Pd alloy could be used as a diffusion layer to prevent diffusion of zinc. The melting temperature of these diffusion barrier layers are all above 1000°C. These diffusion barrier layers can be applied by a number of different techniques including vapour deposition such as chemical vapour deposition, physical vapour deposition, sputtering and pyrolitic deposition.
According to a further aspect of the invention the diffusion barrier layer is a tungsten or tungsten alloy layer which has a melting temperature well above 1000°C. Such a tungsten or tungsten alloy layer will not react with Zn and will prevent diffusion of zinc into the substrate during preheating before hot forming. Diffusion of carbon from the substrate into the tungsten or tungsten alloy diffusion barrier layer may easily occur, but that will not hamper the working of the layer as a Zn-diffusion barrier layer. Depending on thickness of the barrier layer Zn diffusion will be prevented totally or at least to a large extent. Because of the high melting temperature of tungsten a barrier layer of this material is applied preferably by sputtering. The advantage of deposition by sputtering is that it is a relatively easy deposition method to carry out. Because of the effectiveness of tungsten as a barrier layer, a relatively thin barrier layer will be sufficient, that is a thickness in the range of 2-50 nm will be sufficient.
The barrier layer can also be used in other Zn or Zn-based corrosion resistant coatings than the coatings according to the invention. For instance the tungsten barrier layer can be applied on a substrate, such as a steel strip, before the Zn or Zn-based coating is applied by hot dip galvanizing or any other coating method known in the art.
According to still a further aspect of the invention an evaporation barrier is provided on top of the Zn-based coating layer. The high melting point of the Zn-based coating layers according to the invention aids to minimise the coating evaporation and maintain the cathodic corrosion protection by the coating. However, in order to further reduce the evaporation an additional coating is provided on top of the Zn-based coating layer according the invention. This top coating layer does not only prevent evaporation but also reduces the oxidation behaviour of the Zn-based coating layer. Where in the description "evaporation barrier" is used this will also mean a barrier layer with which oxidation of the Zn-based coating layer is reduced as far as applicable. For preventing evaporation it is also important that the diffusion of Zn in this top coating layer is limited. To realize all the above mentioned properties an oxide-based top coating layer with a thickness in the range of 5-1000nm is provided, consisting of for instance chromium oxide (Cr203), indium oxide (In02) or tin oxide (Sn02). Also other oxide films may be possible. The oxides produce a closed surface on top of the coating also when the Zn-based coating layer becomes liquid.
The oxide-based top layer is deposited either as:
■ a closed oxide layer, or
■ as a coating layer that will form an oxide when in contact with air.
A top coating layer of ΤΪΑ1Ν2 forms a continuously renewable aluminium oxide layer on the coating surface at high temperatures, for example during preheating in a hot forming process. This oxide helps to prevent the high-temperature degradation of the nitride.
The feature that the melting temperatures of the Zn-based coatings according to the invention are well above those of the commonly used standard Zn or Zn-based coatings makes a substrate with a Zn-based coatings according to the invention suitable for use in high temperature applications such as press-hardening operations. For that reason it is further provided that the steel substrate is a steel suitable for press- hardening. According to a further aspect if is provided that for this specific application the steel substrate is a strip of boron steel.
According to the invention it is further provided that the Zn-based coating is applied by means of vapour deposition for instance chemical vapour deposition (CVD) and physical vapour deposition (PVD). The deposition by means of PVD allows for a very controlled deposition of the Zn-based coating layer to the required thickness within a narrow range of deviation. This means that the thickness of the Zn-based coating layer can be less than the thickness of such a layer when deposited by means of a hot-dip process. A Zn-based coating applied by hot-dip coating will usually be in the order of ΙΟμιη, whereas a Zn-based coating applied by PVD will be in the range of 2 - ΙΟμιη and preferably in the range of 3 - 8μιη. The more so if diffusion of Zn into the substrate is prevented by means of a barrier layer and evaporation and/or oxidation of constituents of the Zn-based coating layer by means of a top layer.
According to a further aspect of the invention it is provided that the diffusion barrier layer and evaporation/oxidation barrier layer are applied by means of physical vapour deposition which has the same advantages as described for the deposition of the Zn-based coating layer by means of physical vapour deposition. Physical vapour deposition can be carried out using for instance magnetron sputtering. The evaporation barrier layer can also be deposited using other deposition methods such as electroplating.
Example: substrate with ZnMn coating layer after hot-press forming
Steel substrates with dimensions 200 mm x 123 mm were cleaned with Chela clean KC-F25H from Foster, electro-plated at 50°C with a current density of 1.5A/dm2, using a bath with a pH of 5.6, containing zinc sulphate heptahydrate, manganese sulphate monohydrate and tri-sodium citrate dehydrate and subsequently pickled and rinsed. The resulting ZnMn coatings had a thickness of about 3 μιη thickness and contained 40-50 wt.% Mn.
The produced ZnMn coated samples were heated in a Pananalytical X-Ray Diffractometer type Xpert Pro, equipped with a heating cell, in 3 minutes to 900°C, held at this temperature for 6 minutes and subsequently cooled to 400 °C in 1 minute and further to below 100°C within another 7 minutes. During the heating cycle two different gas atmospheres have been used: pure nitrogen or air. The heating cycle is similar to that used in preheat cycles for hot forming processes for car parts.
After the heating cycles the cross sections of the samples were coated with a thin gold coating and analysed. Samples have been investigated mainly by spectral EDX mapping on the SEM, using very high probe currents to increase the speed of analyses. The results show that after annealing in nitrogen the zinc has diffused into the Fe and formed an FeZn layer of about 4 μιη on top of the substrate, and on top of that an Mn- oxide layer of about 2 μιη has formed. After annealing in air all Mn and Zn have oxidised into a MnZn-oxide layer of 4 μιη thick and a very thick layer of iron-oxide is formed (34 μιη).
The results of the samples annealed in nitrogen show that with a single ZnMn layer the Zn will diffuse into the steel substrate to form an iron-zinc phase and the Mn will form an oxide layer. After subsequent hot forming the iron-zinc layer offers cathodic protection to the substrate and the Mn-oxide will constitute a barrier layer if it stays intact.
Adding a diffusion barrier layer in between the substrate and the ZnMn layer and an evaporation barrier layer on top of the ZnMn layer will result in even better cathodic protection by keeping the ZnMn layer more intact during annealing and thus have more Zn and Mn available for cathodic protection in the end product.
The results of the samples annealed in air show that a single ZnMn layer will fully oxidise during the preheat cycle and all potential for cathodic protection after hot forming has been lost in the preheat. This loss can be minimised by applying an evaporation barrier layer on top of the ZnMn coating, which will not only reduce evaporation but will also reduce oxidation of the ZnMn-coating layer.

Claims

1 . Steel substrate provided with a Zn-based corrosion resistant coating, characterized in that the Zn-based coating has a melting temperature above 600°C and wherein the Zn-based coating is a Zn-Mn coating with a Mn content of >19 wt%, a Zn-Sr coating with a Sr content of > 9 wt% or a Zn-Ca coating with a Ca content of > 5 wt%.
2. Steel substrate according to claim 1, wherein the Mn-content in the Zn-Mn coating is in the range of 19 - 30 wt%.
3. Steel substrate according to claim 1, wherein the Sr-content in the Zn-Sr coating is in the range of 9 - 14 wt%.
4. Steel substrate according to claim 1, wherein the Sr-content in the Zn-Sr coating is in the range of 9 - 11 wt%.
5. Steel substrate according to claim 1, wherein the Ca-content in the Zn-Ca coating is in the range of 5 - 24 wt%.
6. Steel substrate according to claim 1, wherein the Ca-content in the Zn-Ca coating is in the range of 5 - 8 wt%.
7. Steel substrate according to one or more of claims 1 - 6, wherein a diffusion barrier layer is provided between the substrate and the Zn-based coating layer.
8. Steel substrate according to claim 7, wherein the diffusion barrier layer is a tungsten or a tungsten alloy layer.
9. Steel substrate according to one or more of claims 1 - 8, wherein an evaporation barrier is provided on top of the Zn-based coating layer.
10. Steel substrate according to claim 9, wherein the evaporation barrier layer is an oxide layer or an oxide forming layer.
1 1 . Steel substrate according to one or more of claims 1 - 10, wherein the steel substrate is a steel suitable for press-hardening.
12. Steel substrate according to claim 11, wherein the steel substrate is a strip of boron steel.
13. Steel substrate according to one or more of claims 1 - 12, wherein the Zn-based coating is applied by means of vapour deposition.
14. Steel substrate according to one or more of claims 1 - 13, wherein the diffusion barrier layer is applied by means vapour deposition or sputtering.
15. Steel substrate according to one or more of claims 1 - 14, wherein the oxide layer or an oxide forming layer is applied by means of physical vapour deposition.
PCT/EP2014/025025 2013-12-18 2014-12-17 Steel substrate provided with corrosion resistant coating with high melting temperature WO2015090621A1 (en)

Priority Applications (2)

Application Number Priority Date Filing Date Title
KR1020167017071A KR20160099588A (en) 2013-12-18 2014-12-17 Steel substrate provided with corrosion resistant coating with high melting temperature
EP14816137.5A EP3084032B1 (en) 2013-12-18 2014-12-17 Steel substrate provided with corrosion resistant coating with high melting temperature and manufacturing method thereof

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
EP13005885 2013-12-18
EP13005885.2 2013-12-18

Publications (1)

Publication Number Publication Date
WO2015090621A1 true WO2015090621A1 (en) 2015-06-25

Family

ID=49955802

Family Applications (1)

Application Number Title Priority Date Filing Date
PCT/EP2014/025025 WO2015090621A1 (en) 2013-12-18 2014-12-17 Steel substrate provided with corrosion resistant coating with high melting temperature

Country Status (3)

Country Link
EP (1) EP3084032B1 (en)
KR (1) KR20160099588A (en)
WO (1) WO2015090621A1 (en)

Cited By (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
WO2018031523A1 (en) * 2016-08-08 2018-02-15 John Speer Modified hot-dip galvanize coatings with low liquidus temperature, methods of making and using the same
DE102018128131A1 (en) 2018-11-09 2020-05-14 Thyssenkrupp Ag Hardened component comprising a steel substrate and an anti-corrosion coating, corresponding component for the production of the hardened component as well as manufacturing method and use
EP3712292A2 (en) 2019-03-19 2020-09-23 ThyssenKrupp Steel Europe AG Component comprising a steel substrate, an intermediate layer and an anticorrosive coating, corresponding cured component and related methods and uses
WO2022200099A1 (en) * 2021-03-24 2022-09-29 Thyssenkrupp Steel Europe Ag Coated flat steel product and method for the production thereof
WO2023174691A1 (en) * 2022-03-14 2023-09-21 Thyssenkrupp Steel Europe Ag Method for coating a substrate with a metal-alloy coating that contains at least two metals

Citations (9)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
GB929262A (en) * 1962-03-05 1963-06-19 Inland Steel Co Aluminizing of ferrous metal base
JPS5837188A (en) * 1981-08-17 1983-03-04 Nippon Kokan Kk <Nkk> Steel plate electroplated with zinc-manganese alloy having excellent corrosion resistance in salt water environment
US5043230A (en) * 1990-05-11 1991-08-27 Bethlehem Steel Corporation Zinc-maganese alloy coated steel sheet
DE4438608A1 (en) * 1993-10-30 1995-05-04 Bayerische Motoren Werke Ag Process for coating an aluminium or steel substrate
US5691071A (en) * 1994-07-28 1997-11-25 Pirelli Coordinamento Pneumatici S.P.A. Surface-treated metal wire for use in the manufacture of reinforcement structures for products made of elastomer material, and a process therefor
WO2008025066A1 (en) * 2006-08-29 2008-03-06 Bluescope Steel Limited Metal-coated steel strip
WO2013023906A1 (en) * 2011-08-17 2013-02-21 Kirchhoff Automotive Deutschland Gmbh Press hardening tool
WO2013091889A1 (en) * 2011-12-23 2013-06-27 Tata Steel Nederland Technology Bv Substrate with a double layered coating
WO2013166429A1 (en) * 2012-05-03 2013-11-07 Magna International Inc. Automotive components formed of sheet metal coated with a non-metallic coating

Patent Citations (9)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
GB929262A (en) * 1962-03-05 1963-06-19 Inland Steel Co Aluminizing of ferrous metal base
JPS5837188A (en) * 1981-08-17 1983-03-04 Nippon Kokan Kk <Nkk> Steel plate electroplated with zinc-manganese alloy having excellent corrosion resistance in salt water environment
US5043230A (en) * 1990-05-11 1991-08-27 Bethlehem Steel Corporation Zinc-maganese alloy coated steel sheet
DE4438608A1 (en) * 1993-10-30 1995-05-04 Bayerische Motoren Werke Ag Process for coating an aluminium or steel substrate
US5691071A (en) * 1994-07-28 1997-11-25 Pirelli Coordinamento Pneumatici S.P.A. Surface-treated metal wire for use in the manufacture of reinforcement structures for products made of elastomer material, and a process therefor
WO2008025066A1 (en) * 2006-08-29 2008-03-06 Bluescope Steel Limited Metal-coated steel strip
WO2013023906A1 (en) * 2011-08-17 2013-02-21 Kirchhoff Automotive Deutschland Gmbh Press hardening tool
WO2013091889A1 (en) * 2011-12-23 2013-06-27 Tata Steel Nederland Technology Bv Substrate with a double layered coating
WO2013166429A1 (en) * 2012-05-03 2013-11-07 Magna International Inc. Automotive components formed of sheet metal coated with a non-metallic coating

Non-Patent Citations (1)

* Cited by examiner, † Cited by third party
Title
VAGGE S T ET AL: "Influence of strontium on electrochemical corrosion behavior of hot-dip galvanized coating", SURFACE AND COATINGS TECHNOLOGY, ELSEVIER, AMSTERDAM, NL, vol. 203, no. 20-21, 15 July 2009 (2009-07-15), pages 3092 - 3098, XP026142619, ISSN: 0257-8972, [retrieved on 20090324], DOI: 10.1016/J.SURFCOAT.2009.03.026 *

Cited By (7)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
WO2018031523A1 (en) * 2016-08-08 2018-02-15 John Speer Modified hot-dip galvanize coatings with low liquidus temperature, methods of making and using the same
DE102018128131A1 (en) 2018-11-09 2020-05-14 Thyssenkrupp Ag Hardened component comprising a steel substrate and an anti-corrosion coating, corresponding component for the production of the hardened component as well as manufacturing method and use
WO2020094285A1 (en) 2018-11-09 2020-05-14 Thyssenkrupp Steel Europe Ag Hardened component, comprising a steel substrate and an anti-corrosion coating, corresponding component for producing the hardened component, production method, and use
EP3712292A2 (en) 2019-03-19 2020-09-23 ThyssenKrupp Steel Europe AG Component comprising a steel substrate, an intermediate layer and an anticorrosive coating, corresponding cured component and related methods and uses
WO2020187929A1 (en) 2019-03-19 2020-09-24 Thyssenkrupp Steel Europe Ag Component comprising a steel substrate, an intermediate layer and an anti-corrosion coating, corresponding hardened component and corresponding methods and uses
WO2022200099A1 (en) * 2021-03-24 2022-09-29 Thyssenkrupp Steel Europe Ag Coated flat steel product and method for the production thereof
WO2023174691A1 (en) * 2022-03-14 2023-09-21 Thyssenkrupp Steel Europe Ag Method for coating a substrate with a metal-alloy coating that contains at least two metals

Also Published As

Publication number Publication date
EP3084032A1 (en) 2016-10-26
EP3084032B1 (en) 2017-09-06
KR20160099588A (en) 2016-08-22

Similar Documents

Publication Publication Date Title
CN103038398B (en) Steel sheet for hot stamping, and process for manufacturing hot-stamped steel products using steel sheet for hot stamping
KR102301116B1 (en) Method for producing a steel component having a metal coating protecting it against corrosion, and steel component
JP5650222B2 (en) Method of manufacturing a steel member with a metal coating that provides protection against corrosion, and steel member
CN101952474B (en) Method for coating a warm or cold-rolled flat steel product comprising 6 - 30 weight-% mn with a metallic protective layer
KR101974182B1 (en) Plated steel plate for hot pressing and hot pressing method of plated steel plate
EP3084032B1 (en) Steel substrate provided with corrosion resistant coating with high melting temperature and manufacturing method thereof
US10253418B2 (en) Steel sheet provided with a coating offering sacrificial cathodic protection, method for the production of a part using such a sheet, and resulting part
US20120085466A1 (en) Method For Producing A Steel Component By Hot Forming And Steel Component Produced By Hot Forming
JP5796142B2 (en) Hot dipping method for steel sheet
JP2014221943A (en) Galvanized steel sheet for hot pressing which is excellent in surface characteristic, hot press forming part using galvanized steel sheet and production method of hot press forming part
CN104981346A (en) Coated steel suitable for hot-dip galvanising
CN114717502A (en) Steel sheet provided with a lanthanum containing coating providing sacrificial cathodic protection
EP4023787A1 (en) Hot stamp molded body
CN105452508A (en) Steel sheet with excellent cut edge corrosion resistance and manufacturing method therefor
TWI652355B (en) Hot-dipped galvanized steel and method of forming the same
JP4816068B2 (en) Method for producing hot-dip galvanized steel sheet with excellent plating adhesion
JP2964911B2 (en) Alloying hot-dip galvanizing method for P-added high-strength steel
US20220170164A1 (en) Method for producing a steel strip with improved bonding of metallic hot-dip coatings
KR101621631B1 (en) Galvannealed steel sheet having high corrosion resistance after painting
KR20110066689A (en) Method for manufacturing high manganese hot dip galvanized steel sheet with superior weldability
CN115443350B (en) Al-plated hot stamped steel
JP5423215B2 (en) Surface-treated steel sheet and manufacturing method thereof
JP2011032498A (en) Surface-treated steel sheet for hot pressing and method for manufacturing hot-pressed member using the same
JPH08170160A (en) Production of silicon-containing high tensile strength hot dip galvanized or galvannealed steel sheet
CN105296906A (en) Galvanization method for steel plate

Legal Events

Date Code Title Description
121 Ep: the epo has been informed by wipo that ep was designated in this application

Ref document number: 14816137

Country of ref document: EP

Kind code of ref document: A1

REEP Request for entry into the european phase

Ref document number: 2014816137

Country of ref document: EP

WWE Wipo information: entry into national phase

Ref document number: 2014816137

Country of ref document: EP

NENP Non-entry into the national phase

Ref country code: DE

ENP Entry into the national phase

Ref document number: 20167017071

Country of ref document: KR

Kind code of ref document: A