EP3728654A1 - Kaltgewalztes stahlflachprodukt mit metallischer korrosionsschutzschicht und verfahren zur herstellung eines solchen - Google Patents
Kaltgewalztes stahlflachprodukt mit metallischer korrosionsschutzschicht und verfahren zur herstellung eines solchenInfo
- Publication number
- EP3728654A1 EP3728654A1 EP18826307.3A EP18826307A EP3728654A1 EP 3728654 A1 EP3728654 A1 EP 3728654A1 EP 18826307 A EP18826307 A EP 18826307A EP 3728654 A1 EP3728654 A1 EP 3728654A1
- Authority
- EP
- European Patent Office
- Prior art keywords
- cold
- annealing
- product
- rolled
- annealed
- Prior art date
- Legal status (The legal status 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 status listed.)
- Pending
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Classifications
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- C—CHEMISTRY; METALLURGY
- C21—METALLURGY OF IRON
- C21D—MODIFYING THE PHYSICAL STRUCTURE OF FERROUS METALS; GENERAL DEVICES FOR HEAT TREATMENT OF FERROUS OR NON-FERROUS METALS OR ALLOYS; MAKING METAL MALLEABLE, e.g. BY DECARBURISATION OR TEMPERING
- C21D8/00—Modifying the physical properties by deformation combined with, or followed by, heat treatment
- C21D8/02—Modifying the physical properties by deformation combined with, or followed by, heat treatment during manufacturing of plates or strips
- C21D8/04—Modifying the physical properties by deformation combined with, or followed by, heat treatment during manufacturing of plates or strips to produce plates or strips for deep-drawing
- C21D8/0421—Modifying the physical properties by deformation combined with, or followed by, heat treatment during manufacturing of plates or strips to produce plates or strips for deep-drawing characterised by the working steps
- C21D8/0426—Hot rolling
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- C—CHEMISTRY; METALLURGY
- C21—METALLURGY OF IRON
- C21D—MODIFYING THE PHYSICAL STRUCTURE OF FERROUS METALS; GENERAL DEVICES FOR HEAT TREATMENT OF FERROUS OR NON-FERROUS METALS OR ALLOYS; MAKING METAL MALLEABLE, e.g. BY DECARBURISATION OR TEMPERING
- C21D8/00—Modifying the physical properties by deformation combined with, or followed by, heat treatment
- C21D8/02—Modifying the physical properties by deformation combined with, or followed by, heat treatment during manufacturing of plates or strips
- C21D8/0221—Modifying the physical properties by deformation combined with, or followed by, heat treatment during manufacturing of plates or strips characterised by the working steps
- C21D8/0236—Cold rolling
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- C—CHEMISTRY; METALLURGY
- C21—METALLURGY OF IRON
- C21D—MODIFYING THE PHYSICAL STRUCTURE OF FERROUS METALS; GENERAL DEVICES FOR HEAT TREATMENT OF FERROUS OR NON-FERROUS METALS OR ALLOYS; MAKING METAL MALLEABLE, e.g. BY DECARBURISATION OR TEMPERING
- C21D8/00—Modifying the physical properties by deformation combined with, or followed by, heat treatment
- C21D8/02—Modifying the physical properties by deformation combined with, or followed by, heat treatment during manufacturing of plates or strips
- C21D8/0221—Modifying the physical properties by deformation combined with, or followed by, heat treatment during manufacturing of plates or strips characterised by the working steps
- C21D8/0226—Hot rolling
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- C—CHEMISTRY; METALLURGY
- C21—METALLURGY OF IRON
- C21D—MODIFYING THE PHYSICAL STRUCTURE OF FERROUS METALS; GENERAL DEVICES FOR HEAT TREATMENT OF FERROUS OR NON-FERROUS METALS OR ALLOYS; MAKING METAL MALLEABLE, e.g. BY DECARBURISATION OR TEMPERING
- C21D8/00—Modifying the physical properties by deformation combined with, or followed by, heat treatment
- C21D8/02—Modifying the physical properties by deformation combined with, or followed by, heat treatment during manufacturing of plates or strips
- C21D8/0247—Modifying the physical properties by deformation combined with, or followed by, heat treatment during manufacturing of plates or strips characterised by the heat treatment
- C21D8/0263—Modifying the physical properties by deformation combined with, or followed by, heat treatment during manufacturing of plates or strips characterised by the heat treatment following hot rolling
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- C—CHEMISTRY; METALLURGY
- C21—METALLURGY OF IRON
- C21D—MODIFYING THE PHYSICAL STRUCTURE OF FERROUS METALS; GENERAL DEVICES FOR HEAT TREATMENT OF FERROUS OR NON-FERROUS METALS OR ALLOYS; MAKING METAL MALLEABLE, e.g. BY DECARBURISATION OR TEMPERING
- C21D8/00—Modifying the physical properties by deformation combined with, or followed by, heat treatment
- C21D8/02—Modifying the physical properties by deformation combined with, or followed by, heat treatment during manufacturing of plates or strips
- C21D8/0247—Modifying the physical properties by deformation combined with, or followed by, heat treatment during manufacturing of plates or strips characterised by the heat treatment
- C21D8/0273—Final recrystallisation annealing
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- C—CHEMISTRY; METALLURGY
- C21—METALLURGY OF IRON
- C21D—MODIFYING THE PHYSICAL STRUCTURE OF FERROUS METALS; GENERAL DEVICES FOR HEAT TREATMENT OF FERROUS OR NON-FERROUS METALS OR ALLOYS; MAKING METAL MALLEABLE, e.g. BY DECARBURISATION OR TEMPERING
- C21D8/00—Modifying the physical properties by deformation combined with, or followed by, heat treatment
- C21D8/02—Modifying the physical properties by deformation combined with, or followed by, heat treatment during manufacturing of plates or strips
- C21D8/04—Modifying the physical properties by deformation combined with, or followed by, heat treatment during manufacturing of plates or strips to produce plates or strips for deep-drawing
- C21D8/0421—Modifying the physical properties by deformation combined with, or followed by, heat treatment during manufacturing of plates or strips to produce plates or strips for deep-drawing characterised by the working steps
- C21D8/0436—Cold rolling
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- C—CHEMISTRY; METALLURGY
- C21—METALLURGY OF IRON
- C21D—MODIFYING THE PHYSICAL STRUCTURE OF FERROUS METALS; GENERAL DEVICES FOR HEAT TREATMENT OF FERROUS OR NON-FERROUS METALS OR ALLOYS; MAKING METAL MALLEABLE, e.g. BY DECARBURISATION OR TEMPERING
- C21D8/00—Modifying the physical properties by deformation combined with, or followed by, heat treatment
- C21D8/02—Modifying the physical properties by deformation combined with, or followed by, heat treatment during manufacturing of plates or strips
- C21D8/04—Modifying the physical properties by deformation combined with, or followed by, heat treatment during manufacturing of plates or strips to produce plates or strips for deep-drawing
- C21D8/0447—Modifying the physical properties by deformation combined with, or followed by, heat treatment during manufacturing of plates or strips to produce plates or strips for deep-drawing characterised by the heat treatment
- C21D8/0463—Modifying the physical properties by deformation combined with, or followed by, heat treatment during manufacturing of plates or strips to produce plates or strips for deep-drawing characterised by the heat treatment following hot rolling
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- C—CHEMISTRY; METALLURGY
- C21—METALLURGY OF IRON
- C21D—MODIFYING THE PHYSICAL STRUCTURE OF FERROUS METALS; GENERAL DEVICES FOR HEAT TREATMENT OF FERROUS OR NON-FERROUS METALS OR ALLOYS; MAKING METAL MALLEABLE, e.g. BY DECARBURISATION OR TEMPERING
- C21D8/00—Modifying the physical properties by deformation combined with, or followed by, heat treatment
- C21D8/02—Modifying the physical properties by deformation combined with, or followed by, heat treatment during manufacturing of plates or strips
- C21D8/04—Modifying the physical properties by deformation combined with, or followed by, heat treatment during manufacturing of plates or strips to produce plates or strips for deep-drawing
- C21D8/0447—Modifying the physical properties by deformation combined with, or followed by, heat treatment during manufacturing of plates or strips to produce plates or strips for deep-drawing characterised by the heat treatment
- C21D8/0473—Final recrystallisation annealing
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- C—CHEMISTRY; METALLURGY
- C21—METALLURGY OF IRON
- C21D—MODIFYING THE PHYSICAL STRUCTURE OF FERROUS METALS; GENERAL DEVICES FOR HEAT TREATMENT OF FERROUS OR NON-FERROUS METALS OR ALLOYS; MAKING METAL MALLEABLE, e.g. BY DECARBURISATION OR TEMPERING
- C21D9/00—Heat treatment, e.g. annealing, hardening, quenching or tempering, adapted for particular articles; Furnaces therefor
- C21D9/46—Heat treatment, e.g. annealing, hardening, quenching or tempering, adapted for particular articles; Furnaces therefor for sheet metals
- C21D9/48—Heat treatment, e.g. annealing, hardening, quenching or tempering, adapted for particular articles; Furnaces therefor for sheet metals deep-drawing sheets
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- C—CHEMISTRY; METALLURGY
- C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
- C22C—ALLOYS
- C22C38/00—Ferrous alloys, e.g. steel alloys
- C22C38/001—Ferrous alloys, e.g. steel alloys containing N
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- C—CHEMISTRY; METALLURGY
- C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
- C22C—ALLOYS
- C22C38/00—Ferrous alloys, e.g. steel alloys
- C22C38/02—Ferrous alloys, e.g. steel alloys containing silicon
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- C—CHEMISTRY; METALLURGY
- C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
- C22C—ALLOYS
- C22C38/00—Ferrous alloys, e.g. steel alloys
- C22C38/04—Ferrous alloys, e.g. steel alloys containing manganese
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- C—CHEMISTRY; METALLURGY
- C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
- C22C—ALLOYS
- C22C38/00—Ferrous alloys, e.g. steel alloys
- C22C38/06—Ferrous alloys, e.g. steel alloys containing aluminium
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- C—CHEMISTRY; METALLURGY
- C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
- C22C—ALLOYS
- C22C38/00—Ferrous alloys, e.g. steel alloys
- C22C38/12—Ferrous alloys, e.g. steel alloys containing tungsten, tantalum, molybdenum, vanadium, or niobium
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- C—CHEMISTRY; METALLURGY
- C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
- C22C—ALLOYS
- C22C38/00—Ferrous alloys, e.g. steel alloys
- C22C38/14—Ferrous alloys, e.g. steel alloys containing titanium or zirconium
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- C—CHEMISTRY; METALLURGY
- C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
- C22C—ALLOYS
- C22C38/00—Ferrous alloys, e.g. steel alloys
- C22C38/18—Ferrous alloys, e.g. steel alloys containing chromium
- C22C38/20—Ferrous alloys, e.g. steel alloys containing chromium with copper
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- C—CHEMISTRY; METALLURGY
- C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
- C22C—ALLOYS
- C22C38/00—Ferrous alloys, e.g. steel alloys
- C22C38/18—Ferrous alloys, e.g. steel alloys containing chromium
- C22C38/26—Ferrous alloys, e.g. steel alloys containing chromium with niobium or tantalum
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- C—CHEMISTRY; METALLURGY
- C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
- C22C—ALLOYS
- C22C38/00—Ferrous alloys, e.g. steel alloys
- C22C38/18—Ferrous alloys, e.g. steel alloys containing chromium
- C22C38/30—Ferrous alloys, e.g. steel alloys containing chromium with cobalt
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- C—CHEMISTRY; METALLURGY
- C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
- C22C—ALLOYS
- C22C38/00—Ferrous alloys, e.g. steel alloys
- C22C38/18—Ferrous alloys, e.g. steel alloys containing chromium
- C22C38/40—Ferrous alloys, e.g. steel alloys containing chromium with nickel
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- 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
- C23C2/00—Hot-dipping or immersion processes for applying the coating material in the molten state without affecting the shape; Apparatus therefor
- C23C2/04—Hot-dipping or immersion processes for applying the coating material in the molten state without affecting the shape; Apparatus therefor characterised by the coating material
- C23C2/06—Zinc or cadmium or alloys based thereon
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- 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
- C23C2/00—Hot-dipping or immersion processes for applying the coating material in the molten state without affecting the shape; Apparatus therefor
- C23C2/26—After-treatment
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- 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
- C23C6/00—Coating by casting molten material on the substrate
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- 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
- C25D3/22—Electroplating: Baths therefor from solutions of zinc
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- C—CHEMISTRY; METALLURGY
- C25—ELECTROLYTIC OR ELECTROPHORETIC PROCESSES; APPARATUS THEREFOR
- C25F—PROCESSES FOR THE ELECTROLYTIC REMOVAL OF MATERIALS FROM OBJECTS; APPARATUS THEREFOR
- C25F1/00—Electrolytic cleaning, degreasing, pickling or descaling
- C25F1/02—Pickling; Descaling
- C25F1/04—Pickling; Descaling in solution
- C25F1/06—Iron or steel
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- 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
- C23G—CLEANING OR DE-GREASING OF METALLIC MATERIAL BY CHEMICAL METHODS OTHER THAN ELECTROLYSIS
- C23G1/00—Cleaning or pickling metallic material with solutions or molten salts
- C23G1/02—Cleaning or pickling metallic material with solutions or molten salts with acid solutions
- C23G1/08—Iron or steel
Definitions
- the invention relates to a method for producing a coated with a metallic corrosion protection layer, cold-rolled steel flat product with reduced tendency to Wasserstoffaufnähme during production and processing Hamiltonverar and a cold-rolled, finally annealed and coated with a metallic corrosion protection layer steel flat product.
- Hydrogen embrittlement is similar to material fatigue because the damage takes time. As a consequence, hydrogen-induced crack formation can occur and there is a risk of a delayed brittle fracture.
- EP 3 020 842 A1 already discloses a flat steel product with an internal surface-adjacent Si or Mn oxide layer.
- the thickness of the Si or Mn oxide layer is 4 ⁇ m or more.
- the thickness of the oxide layer is adjusted by the coiler temperature after hot rolling.
- the oxide layer increases the hydrogen embrittlement resistance of the steel product.
- EP 3027784 Bl describes a silicon-containing, microalloyed high-strength multiphase steel having a maximum Si content of 0.8% by weight.
- the production of the steel optionally includes annealing the hot strip and annealing the cold strip.
- An object of the invention is based can be seen to produce a high-strength, galvanized steel flat product with high resistance to hydrogen embrittlement and thus to create a product that is particularly suitable for use in safety-related structures for body applications. Further, the invention aims to provide a method for producing a zinc-coated steel flat product having high hydrogen embrittlement resistance.
- the object underlying the invention is achieved by a method for producing a coated with a metallic corrosion protection layer, cold-rolled steel flat product with reduced tendency to hydrogen absorption during production and further processing.
- the process comprises the following steps: melting a molten steel containing (in% by weight): C: 0.01-0.35%, Mn: 1-4%, Si: 0.5-2.5%, Nb : up to 0.2%, Ti: up to 0.2%, P: up to 0.1%, Al: up to 1.5%, S: up to 0.01%, N: up to 0, 1%, and optionally one or more elements from the group of rare earth metals, Mo, Cr, Zr, V, W, Co, Ni, B, Cu, Ca, with rare earth metals: up to 0.2%, Mo: up to 1%, Cr: up to 3%, Zr: up to 1%, V: up to 1%, W: up to 1%, Co: up to 1%, Ni: up to 2%, B: up to 0 , 1%, Cu: up to 3%, Ca: up to 0.015%, the remainder iron and unavoidable impurities; Casting the molten steel into a precursor; Hot rolling the precursor into a hot strip, the hot rolling end temperature
- a starting point of the inventive considerations was based on the finding that a hydrogen entry in the Me tallgitter even after applying the corrosion protective layer (galvanizing) can take place to a considerable extent, especially in the downstream process steps of phosphating and cathodic dip painting (KTL) , These process steps are usually carried out by the customer, but still "subsequently" increase the concentration of hydrogen in the metal grid and thus the risk of a delayed brittle fracture.
- KTL cathodic dip painting
- a thin Si enrichment layer can be formed between a surface and the base material of the cold rolled and finish annealed steel flat whose maximum Si content is higher than the Si content of the base material by a factor between three and eight and the depth between them 10 nm and 1 ym, measured from the surface of the flat steel product.
- This Si enrichment layer serves as an effective inhibiting layer against the diffusion of atomic hydrogen into the metal grid of the flat steel product.
- the layer minimizes the hydrogen uptake at all loading steps after their production, ie in particular during pickling, the electrolytic galvanizing or optionally hot dip galvanizing and in the said subsequent processing steps (phosphating, KTL), which were previously not sufficiently considered with respect to their importance for the incorporation of hydrogen into the metal grid.
- the annealing of the hot strip is carried out at a more than 550 ° C and up to 730 ° C amount annealing temperature.
- the annealing of the (optionally pickled) hot strip produces a near-surface initial Si-enrichment layer, the presence of which is the subsequent near-surface increase in the
- Si content Si enrichment layer
- Si enrichment layer Si content (Si enrichment layer), which is achieved (only) in the final annealing of the cold-rolled steel flat product, favors.
- the annealing of the hot strip is preferably carried out over an annealing period of 20-40 hours. It has been found that with these annealing times a suitable initial Si enrichment layer can be achieved when using the abovementioned Si concentrations in the flat steel product.
- the minimum Si content of the initial Si enrichment layer may be 20% or more higher than the Si content of the base material of the flat steel product. Furthermore, the depth of the initial Si enrichment layer can be at most 100 nm, in particular 80 nm, in particular 50 nm, 30 nm, 20 nm or 10 nm, measured from the surface of the hot strip.
- the finish annealing of the cold-rolled steel flat product can be carried out over an annealing period of 60 - 900 seconds. Already at short annealing time between z. In the cold-rolled steel flat product, for example, 60 and 180 seconds form an Si-enrichment layer between a surface and the base material of the cold-rolled and final annealed flat steel product, which effectively inhibits subsequent hydrogen diffusion.
- the maximum Si content of the Si enrichment layer may be higher than the Si content of the base material by a factor between 3 and 8. Experiments have shown that preferably an increase by a factor between 4 and 6 can be provided. Furthermore, the depth of the Si-enrichment layer may be at most 1 ⁇ m, 500 nm, 300 nm, 100 nm, 80 nm, 50 nm, 30 nm or 20 nm, measured from the surface of the flat steel product.
- a cold-rolled, finish-annealed and coated steel flat product has the composition of elements given above in relation to the method according to the invention. Percentages based on material compositions are in this document always in wt .-%.
- the Si content of the base material of the flat steel product is required for the formation of the Si enrichment layer, the Si content is preferably between 0.7% and 2.5%, preferably 0.8% and 2.0%, in particular between 1 , 2% and 2.0%.
- the higher the Si content of the base material the greater the maximum concentration of Si in the Si enrichment layer (with otherwise identical manufacturing parameters).
- silicon also causes a binding of oxygen during the casting of the steel.
- the C content of the flat steel product is between 0.15% and 0.25%.
- the carbon content may be below the maximum limit of 0.23% for dual phase steels.
- excessive carbon contents increase the hardness difference between ferrite and martensite and reduce weldability.
- the Mn content is 2 - 3%.
- Manganese (Mn) increases the strength of the steel product by solid solution hardening.
- relatively high Mn contents can be used without negatively affecting the formation of the inventions to the invention Si-enrichment layer on the surface of the flat steel product.
- Aluminum (Al) binds the dissolved oxygen in the iron and nitrogen. Further, Al, like Si, shifts ferrite formation to shorter times, allowing the formation of sufficient ferrite in dual phase steel. Conventionally, therefore, Al is also used to substitute a part of Si since it is described as less critical to the galvanizing reaction than silicon. However, since comparatively high Si contents are provided according to the invention, Al can preferably be used only in low concentrations below 1.0%, 0.5%, in particular below 0.1%.
- compositions also relate to relatively low concentrations of the metals niobium (Nb), titanium (Ti), chromium (Cr), cobalt (Co), nickel (Ni) and / or copper (Cu).
- Nb up to 0.1%, in particular up to 0.05%
- Ti 0.005 to 0.1%, in particular 0.03-0.0%
- Cr up to 0.1%
- Co up to 0.1%
- Ni up to 0.1%
- / or Cu up to 0.1%.
- FIG. 1 shows a schematic representation of a process sequence for the production of a flat steel product according to the invention.
- Figure 2 is a graph showing the Si content in the flat steel product before hot strip annealing versus the distance from the surface of the flat steel product for a base material having an Si content of 1.45%.
- Figure 3 is a graph showing the Si content in the steel flat product after hot strip annealing and before cold rolling depending on the distance from the surface of the flat steel product for a base material having an Si content of 1.45%.
- Figure 4 shows a graph in which the Si content in the steel flat product of the finished material (i.e.
- Figure 5 shows a graph in which the Si content in the steel flat product of the finished material (i.e.
- Figure 6 is a graph showing the hydrogen uptake when performing a pickling step in electrolytic galvanizing depending on the time taken by the picking step for a flat steel product having different Si contents.
- FIG. 7 shows a graph in which the mean time until breakage of a flat steel product versus a loading time during pickling for different Si contents of a flat steel product is shown.
- Figure 8 shows a graph in which the average hydrogen content in a corrosion test against corrosion time periods of 0 to 6 weeks for a stretched steel flat product for different Si contents is plotted.
- Starting point of steelmaking is a blast furnace process 1, in which a molten steel is melted.
- the molten steel has a composition within the ranges indicated above. This is followed by casting 2 of the steel, with which precursors, for example so-called rolling ingots, are produced.
- a heating or holding of the precursors can be provided at a preheating temperature of 1000 to 1300 ° C., preferably 1150 to 1250 ° C.
- the casting 2 of the molten steel (for example,
- Continuous casting) (and optionally preheated) precursors are then hot rolled in a rolling mill 3.
- the hot rolling is carried out at a rolling end temperature between 820-1000 ° C, preferably 840-920 ° C.
- pickling of the hot strip in station 4 can be carried out.
- the pickling removes the surface oxides resulting from hot rolling, which could also have an inhibiting effect on hydrogen absorption.
- the hot strip is coiled in station 5 to form a coil.
- the reel temperature can vary over a wide range and, for example, from room temperature to about 750 ° C, preferably 450 to 700 ° C.
- the wound into a coil hot strip is then annealed, ie reheated.
- the annealing of the hot strip is carried out in a hot strip annealing station 6 on the wound coil at a more than 530 ° C and up to 950 ° C, preferably 550 ° C to 650 ° C amount annealing temperature.
- the annealing time is in the range of 1 to 50 hours, preferably 20 to 40 hours.
- the hot strip annealing is preferably carried out by a bell annealing, whereby the relatively long annealing periods and a uniform temperature distribution can be achieved cost-effectively.
- the annealing of the hot strip is a process step necessary for the later formation of the Si enrichment layer according to the invention. As will be explained in more detail below it has been shown that in the hot strip annealing (initially) an initial Si-enrichment layer near the surface of the hot strip is generated, the near the surface for near future Si redistribution to form the thin, hydrogen diffusion-inhibiting Si enrichment layer is needed.
- the Si enrichment in near-surface regions of the hot strip to form the initial Si-enrichment layer is dependent on both the annealing time and the annealing temperature in hot strip annealing.
- the hot strip annealing temperature may be equal to or greater than or less than 550 ° C, 600 ° C, 650 ° C, 700 ° C, 750 ° C, 800 ° C, 850 ° C or 900 ° C.
- the annealing time may be equal to or less than or greater than 5 hours, 10 hours, 15 hours, 20 hours, 24 hours, 30 hours, 35 hours, 40 hours or 45 hours.
- the total cold rolling degree may be at least 45% or higher, e.g. equal to or greater than 50%, 55%, 60% or 65%.
- the cold rolled flat steel product is at a final annealing temperature between 650 ° C to 920 ° C
- the final annealing is in a final annealing station 8, for example, a continuous annealing furnace Runaway leads.
- the final annealing step may be performed at a temperature equal to or greater than or less than 700 ° C, 750 ° C, 800 ° C, 850 ° C, or 900 ° C.
- the annealing time of the final annealing step is between 30 and 1500 seconds (s).
- the annealing time of the final annealing step can be in particular between 60 s and 900 s, with annealing times equal to or less than or greater than 120 s, 180 s, 240 s or 300 s can be selected.
- the cold-rolled and finally annealed flat steel product is coated with a metallic corrosion protection layer based on zinc.
- the galvanizing by means of a electrolytic galvanic galvanizing (ELO) in an electrolytic Galvanizing 9 done.
- ELO electrolytic galvanic galvanizing
- the pretreatment may include various mechanical cleaning steps, such as brush degreasing and the like.
- an electrolytic picking step is usually carried out, which includes anodic iron dissolution and residue removal.
- the electrolytic Dekapieruze which can be carried out for example with alternating current, already takes place a cathodic charging reaction, which causes an increased risk of hydrogen absorption in the metal grid.
- the galvanizing can be done on one side or on both sides. It can be carried out on a continuous steel belt and, for example, at a speed of 10 to 200 m / min, preferably 80 to 140 m / min.
- the process of galvanizing causes a cathodic loading charge reaction, which can have a hydrogen absorption in the metal grid result.
- a cathodic loading charge reaction which can have a hydrogen absorption in the metal grid result.
- Si enrichment layer on the surface of the Stahlflachpro product has been shown that in the electrolytic galvanizing depending on the plant operating mode up to 0.3 ppm of diffusive hydrogen (isothermal measured at 350 ° C) can be included in the metal grid.
- Hot-dip galvanizing possible The actual galvanizing (electroplating or Schmelztauchver tines) is usually followed by an aftertreatment of the galvanized steel flat product, which is not provided in Figure 1 is and, for example, a phosphating, a Pas sivate and / or may include oiling of the flat steel product. These process steps can also bring about a further loading with hydrogen and the risk of it penetrating into the metal grid of the flat steel product.
- Si enrichment layer a hydrogen uptake of up to 0.2 ppm (at a heating rate of 20 K / s to 900 ° C) tallgitter measured in the Me.
- Si enrichment layer for inhibiting or retarding the diffusion of hydrogen into the base metal of the
- Figure 2 shows the silicon profile (in weight percent) as a function of the depth measured from the surface of the hot strip prior to hot strip annealing.
- the Si content of the hot strip (or the
- FIG. 2 shows that there is a relatively constant or uniform silicon profile versus depth.
- FIG. 2 shows the state of the hot strip after pickling 4 and documents that previous anneals in the process path do not cause Si enrichment at the surface of the pickled hot strip.
- FIG. 3 shows the course of the Si content (silicon profile) after the hot strip annealing.
- the figure makes it clear that a significant initial Si enrichment layer was created between the surface and a base material of the annealed hot strip. For example, it has been found that a maximum Si content of the initial Si enrichment layer is 20% or more higher than the Si content of the base material.
- the initial Si-enrichment layer in the example shown here has a layer thickness of about 10 nm, measured from the surface. It has been found that layer thicknesses equal to or less than 100 nm, 80 nm, 50 nm, 40 nm, 30 nm or 20 nm are possible.
- FIG. 4 shows the silicon profile (profile of the Si content) in the finished material, ie after the final annealing of the cold-rolled flat steel product. Shown are the silicon profiles of two flat steel products with identical Si content of 1.45%, wherein the curves 4_la and 4_lb a first flat steel product measured from the top (index a) and from the bottom (index b) relate and the curves 4_2a and 4_2b denote a second flat steel product, from which also measurements are made at the top (index a) and at the bottom (index b). were taken. It can be seen that in all cases a clear formation of an Si enrichment layer has taken place near the surface. The Si-enrichment layer may have a greater depth than the initial Si-enrichment layer.
- the depth of the Si-enrichment layer in the examples shown here is about 0.06 ⁇ m (ie 60 nm), with larger layer thicknesses, for example equal to or less than 500 nm, 300 nm, 200 nm, 150 nm, 100 nm, 80 nm , or even small layer thicknesses equal to or less than 50 nm, 30 nm or 20 nm may occur.
- FIG. 4 shows that an enrichment of the Si content by more than a factor of 4 compared to the Si content of the base material is possible.
- the maximum Si content of the Si enrichment layer may, for example, be greater than the Si content of the base material of the cold-rolled and finally annealed flat steel product by a factor of 3, 4, 5, 6, 7 or 8.
- the Si-enrichment layer may have a larger Si enrichment factor
- Figure 5 shows by way of example the silicon profile of a material having a Si content of less than 0.02% in the finished material, i. as in Figure 4 after the final annealing.
- FIG. 5 clarifies that no effective Si-enrichment layer forms in this non-inventive material, since the Si concentration in the base material for this is obviously not sufficiently high.
- FIG. 6 documents the effectiveness of the solution according to the invention. Plotted is the mean hydrogen content in the metal lattice in ppm compared to the loading time in the picking step, which, as already described, in the case of lytic galvanizing in the galvanizing plant 9 is performed. The measurements were carried out on flat steel products with different Si contents (without Si, 0.85% Si, 1.5% Si).
- FIG. 6 shows that hydrogen uptake generally increases with increasing loading time. This applies both to loading durations in the range of 6 to 180 seconds, which are realistic durations for the practice (in particular, short loading periods of between 6 and 100 seconds, if possible shorter than 80, 60, 40, 20 seconds), as well as for longer ones Loading periods in which the hydrogen input into the metal grid continues to increase continuously.
- FIG. 6 clarifies that in the case of the process control selected here, an Si content of 0.85% does not effectively bind the hydrogen absorption for shorter charging periods, while for relatively long charging periods, this relatively low Si content also prevents the entry of diffusible hydrogen into the hydrogen Metal grid significantly inhibits.
- the Si enrichment layer formed at a Si content of 1.5%, however, even at shorter load periods allows a very effective suppression of hydrogen absorption at Deka pier Colour.
- Si enrichment layer in the finished material can be dependent not only on the Si content, but also on the process management in the manufacture position of the flat steel product, in particular special from the process control in hot strip annealing and the process control in the final annealing of the cold-rolled steel flat product.
- a relatively low Si content of 0.85% in the context of the invention may also have a certain effectiveness even with shorter loading periods show the penetration of hydrogen.
- FIG. 6 shows that, in any case, at higher Si contents, the activity of the Si enrichment layer according to the invention becomes clear
- the Si content may preferably be equal to or greater than 0.5%, 0.6%, 0.7%, 0.8%, 0.9%, 1.0%, 1.1%, 1.2%. , 1.3%, 1.4%, 1.5%, 1.6%, 1.7%, 1.8% or 1.9%.
- FIG. 6 relates to the loading time of the picking step, it is to be assumed that a similar behavior will occur in other processes in which a loading of hydrogen likewise occurs. This means that the Si enrichment layer according to the invention can also effectively delay or inhibit the entry of hydrogen into the metal grid in other loading processes.
- Figure 7 also serves to illustrate the effectiveness of the inventive solution described herein. Shown is the mean time to fracture of a flat steel product sample in hours (h) versus loading time in seconds (s). The graph shows that at relatively low loading durations of 6 and 30 seconds, no influence on the fracture behavior of the steel flat product samples (at the considered load durations) is detectable. At higher loading times from 180 seconds and more, the steel flat product sample with a Si enrichment layer based on an Si content of 1.5% shows a significantly better breaking strength than the comparative samples. This is due, as already described, to the barrier effect of the Si enrichment layer against the entry of diffusible hydrogen into the metal grid.
- the effectiveness of the Si enrichment layer according to the invention over loading processes in elec trolytic galvanizing has been demonstrated (in particular during the decapping step).
- additional signi ficant absorption of hydrogen into the steel can take place even in downstream customer processes. It is therefore assumed that the protective properties of the thin Si enrichment layer illustrated in FIGS. 6 and 7 are also effective in downstream customer processes.
- the Si enrichment layer according to the invention thus also enables protection of the galvanized steel flat product from hydrogen-induced cracking due to loading processes, which take place outside the sphere of influence of Stahlher stellers.
- FIG. 8 shows the mean hydrogen content (in ppm) of the cyclic corrosion resistance VDA 233-102 on galvanized and stretched samples with uniform corrosion over periods of corrosion of 0 to 6 weeks.
- VDA 233-102 the corrosion behavior of materials and components as well as the corrosion protection by coating systems can be determined with a time-consuming test procedure.
- the corrosion resistance VDA 233-102 simulates the corrosion behavior of samples of galvanized and stretched steels, such as those used in the automotive industry. It can be seen that the higher Si content samples show a reduced hydrogen uptake, even after a relatively long time. After the first week of corrosion of the test, no significant hydrogen uptake seems to take place. Examples
- Table 1 shows steel compositions (alloys) Nos. 1 to 6.
- the alloys 1 to 5 are alloys according to the invention, while the alloy 6 is not according to the invention due to the low Si content.
- the residual content consists in all cases of iron and the unavoidable impurities, optionally also of the aforementioned optional elements.
- Table 2 shows process parameters and hydrogen uptake of the steel compositions (alloys) Nos. 1 to 6.
- the Automatglühzeit corresponds to the sum of the annealing time of the hot strip and the annealing time of the final annealing, due to the significantly longer hot strip annealing times the total annealing times are approximately interpreted as (upper limits of the) hot strip annealing time.
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Abstract
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DE102017223633.7A DE102017223633A1 (de) | 2017-12-21 | 2017-12-21 | Kaltgewalztes Stahlflachprodukt mit metallischer Korrosionsschutzschicht und Verfahren zur Herstellung eines solchen |
PCT/EP2018/085664 WO2019121793A1 (de) | 2017-12-21 | 2018-12-18 | Kaltgewalztes stahlflachprodukt mit metallischer korrosionsschutzschicht und verfahren zur herstellung eines solchen |
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US (1) | US11473160B2 (de) |
EP (1) | EP3728654A1 (de) |
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US11613789B2 (en) | 2018-05-24 | 2023-03-28 | GM Global Technology Operations LLC | Method for improving both strength and ductility of a press-hardening steel |
CN112534078A (zh) | 2018-06-19 | 2021-03-19 | 通用汽车环球科技运作有限责任公司 | 具有增强的机械性质的低密度压制硬化钢 |
US11530469B2 (en) | 2019-07-02 | 2022-12-20 | GM Global Technology Operations LLC | Press hardened steel with surface layered homogenous oxide after hot forming |
CN111185771A (zh) * | 2020-01-16 | 2020-05-22 | 浙江建鑫型钢科技有限公司 | 一种精细光亮的扁钢加工方法 |
CN113399456B (zh) * | 2021-06-30 | 2023-04-25 | 新余钢铁股份有限公司 | 一种超薄规格65Mn冷轧宽钢带及其制造方法 |
CN114411057B (zh) * | 2021-12-30 | 2022-12-16 | 钢铁研究总院 | 一种可烧结摩擦层的高强心板用钢 |
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US3420760A (en) * | 1965-04-30 | 1969-01-07 | Gen Dynamics Corp | Process for descaling steel strip in an aqueous organic chelating bath using alternating current |
JP5082451B2 (ja) | 2006-01-24 | 2012-11-28 | Jfeスチール株式会社 | 深絞り性と延性に優れた高強度冷延鋼板の製造方法、およびその冷延鋼板を用いた高強度溶融亜鉛めっき鋼板の製造方法 |
DE102008057151A1 (de) | 2008-11-13 | 2010-05-27 | Henkel Ag & Co. Kgaa | Verfahren zum Herstellen eines elektrolytisch verzinkten hochfesten Stahlbleches |
EP2383353B1 (de) * | 2010-04-30 | 2019-11-06 | ThyssenKrupp Steel Europe AG | Höherfester, Mn-haltiger Stahl, Stahlflachprodukt aus einem solchen Stahl und Verfahren zu dessen Herstellung |
JP5825206B2 (ja) * | 2011-07-06 | 2015-12-02 | 新日鐵住金株式会社 | 冷延鋼板の製造方法 |
DE102012013113A1 (de) * | 2012-06-22 | 2013-12-24 | Salzgitter Flachstahl Gmbh | Hochfester Mehrphasenstahl und Verfahren zur Herstellung eines Bandes aus diesem Stahl mit einer Mindestzugfestigkleit von 580MPa |
JP2015034334A (ja) | 2013-07-12 | 2015-02-19 | 株式会社神戸製鋼所 | めっき性、加工性、および耐遅れ破壊特性に優れた高強度めっき鋼板、並びにその製造方法 |
DE102013013067A1 (de) | 2013-07-30 | 2015-02-05 | Salzgitter Flachstahl Gmbh | Siliziumhaltiger, mikrolegierter hochfester Mehrphasenstahl mit einer Mindestzugfestigkeit von 750 MPa und verbesserten Eigenschaften und Verfahren zur Herstellung eines Bandes aus diesem Stahl |
BR112016012424B1 (pt) | 2013-12-11 | 2019-08-27 | Arcelormittal | folha de aço martensítico, diretamente obtida após laminação a frio, recozimento e resfriamento e método para produzir uma folha de aço martensítico laminada a frio e recozida |
WO2015177582A1 (fr) | 2014-05-20 | 2015-11-26 | Arcelormittal Investigación Y Desarrollo Sl | Tôle d'acier doublement recuite à hautes caractéristiques mécaniques de résistance et ductilité, procédé de fabrication et utilisation de telles tôles |
EP3219821B1 (de) | 2015-01-15 | 2019-11-13 | JFE Steel Corporation | Hochfestes feuerverzinktes stahlblech und herstellungsverfahren dafür |
DE102015111866A1 (de) * | 2015-07-22 | 2017-01-26 | Salzgitter Flachstahl Gmbh | Umformbarer Leichtbaustahl mit verbesserten mechanischen Eigenschaften und Verfahren zur Herstellung von Halbzeug aus diesem Stahl |
DE102015112889A1 (de) * | 2015-08-05 | 2017-02-09 | Salzgitter Flachstahl Gmbh | Hochfester manganhaltiger Stahl, Verwendung des Stahls für flexibel gewalzte Stahlflachprodukte und Herstellverfahren nebst Stahlflachprodukt hierzu |
DE102015112886A1 (de) * | 2015-08-05 | 2017-02-09 | Salzgitter Flachstahl Gmbh | Hochfester aluminiumhaltiger Manganstahl, ein Verfahren zur Herstellung eines Stahlflachprodukts aus diesem Stahl und hiernach hergestelltes Stahlflachprodukt |
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- 2017-12-21 DE DE102017223633.7A patent/DE102017223633A1/de active Pending
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- 2018-12-18 US US16/956,301 patent/US11473160B2/en active Active
- 2018-12-18 WO PCT/EP2018/085664 patent/WO2019121793A1/de unknown
- 2018-12-18 EP EP18826307.3A patent/EP3728654A1/de active Pending
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US20200325552A1 (en) | 2020-10-15 |
US11473160B2 (en) | 2022-10-18 |
DE102017223633A1 (de) | 2019-06-27 |
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