EP4092141A1 - Produit plan en acier doté d'un revêtement al, son procédé de fabrication, composant en acier et son procédé de fabrication - Google Patents

Produit plan en acier doté d'un revêtement al, son procédé de fabrication, composant en acier et son procédé de fabrication Download PDF

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Publication number
EP4092141A1
EP4092141A1 EP21175294.4A EP21175294A EP4092141A1 EP 4092141 A1 EP4092141 A1 EP 4092141A1 EP 21175294 A EP21175294 A EP 21175294A EP 4092141 A1 EP4092141 A1 EP 4092141A1
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EP
European Patent Office
Prior art keywords
steel
protective coating
mass fraction
flat
weight
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EP21175294.4A
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German (de)
English (en)
Inventor
David Hoffmann
Dr. Oliver Moll
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ThyssenKrupp Steel Europe AG
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ThyssenKrupp Steel Europe AG
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Priority to EP21175294.4A priority Critical patent/EP4092141A1/fr
Priority to PCT/EP2022/063495 priority patent/WO2022243397A1/fr
Priority to CN202280036669.9A priority patent/CN117355620A/zh
Priority to EP22729619.1A priority patent/EP4341454A1/fr
Publication of EP4092141A1 publication Critical patent/EP4092141A1/fr
Withdrawn legal-status Critical Current

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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
    • C23C2/12—Aluminium or alloys based thereon
    • 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
    • C21D1/00—General methods or devices for heat treatment, e.g. annealing, hardening, quenching or tempering
    • C21D1/26—Methods of annealing
    • 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
    • C21D1/00—General methods or devices for heat treatment, e.g. annealing, hardening, quenching or tempering
    • C21D1/26—Methods of annealing
    • C21D1/28—Normalising
    • 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
    • C21D1/00—General methods or devices for heat treatment, e.g. annealing, hardening, quenching or tempering
    • C21D1/62—Quenching devices
    • C21D1/673—Quenching devices for die quenching
    • 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
    • C21D6/00—Heat treatment of ferrous alloys
    • C21D6/005—Heat treatment of ferrous alloys containing Mn
    • 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
    • C21D7/00—Modifying the physical properties of iron or steel by deformation
    • C21D7/13—Modifying the physical properties of iron or steel by deformation by hot working
    • 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
    • C21D8/0478—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 involving a particular surface treatment
    • C21D8/0484—Application of a separating or insulating coating
    • 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
    • C—CHEMISTRY; METALLURGY
    • C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
    • C22C—ALLOYS
    • C22C21/00—Alloys based on aluminium
    • C—CHEMISTRY; METALLURGY
    • C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
    • C22C—ALLOYS
    • C22C21/00—Alloys based on aluminium
    • C22C21/02—Alloys based on aluminium with silicon as the next major constituent
    • C22C21/04—Modified aluminium-silicon alloys
    • C—CHEMISTRY; METALLURGY
    • C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
    • C22C—ALLOYS
    • C22C21/00—Alloys based on aluminium
    • C22C21/06—Alloys based on aluminium with magnesium as the next major constituent
    • C—CHEMISTRY; METALLURGY
    • C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
    • C22C—ALLOYS
    • C22C21/00—Alloys based on aluminium
    • C22C21/06—Alloys based on aluminium with magnesium as the next major constituent
    • C22C21/08—Alloys based on aluminium with magnesium as the next major constituent with silicon
    • 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
    • C23C2/28—Thermal after-treatment, e.g. treatment in oil bath
    • 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
    • C23C30/00—Coating with metallic material characterised only by the composition of the metallic material, i.e. not characterised by the coating process

Definitions

  • the invention relates to a steel flat product for hot forming consisting of a steel substrate composed of a steel containing 0.1-3 wt.% Mn and optionally up to 0.01 wt.% B and a protective coating applied to the steel substrate based on Al, which optionally contains a total of up to 20% by weight of other alloying elements.
  • the invention also relates to a method for producing a flat steel product according to the invention.
  • flat steel product includes all rolled products whose length is much greater than their thickness. This includes steel strips and sheets as well as blanks and blanks made from them.
  • the invention relates to a steel component produced by hot forming.
  • hot press hardening also known as hot forming
  • steel blanks which are separated from cold- or hot-rolled steel strip, are heated to a deformation temperature that is generally above the austenitization temperature of the respective steel and placed in the heated state in the tool of a forming press.
  • the sheet metal blank or the component formed from it experiences rapid cooling through contact with the cool tool.
  • the cooling rates are set in such a way that a hardened structure results in the component.
  • the structure is transformed into a martensitic structure.
  • the invention also relates to a method for producing such a steel component.
  • Typical steels suitable for hot press hardening are steels A-E, the chemical composition of which is listed in Table 2.
  • MnB steel For hot-rolled MnB steel sheets provided with an Al coating, which are intended for the production of steel components by hot press form hardening, is in EP 0 971 044 B1 an alloy specification is given according to which, in addition to iron and unavoidable impurities (in % by weight), MnB steel has a carbon content of more than 0.20% but less than 0.5%, a manganese content of more than 0.5%, but less than 3%, a silicon content of More than 0.1% but less than 0.5% Chromium more than 0.01% but less than 1% Titanium less than 0.2% Aluminum less than 0.1% , a phosphorus content of less than 0.1%, a sulfur content of less than 0.05% and a boron content of more than 0.0005% but less than 0.08%.
  • the Al coating is a so-called AISi coating, which consists of 9-10% by weight Si, 2-3.5% by weight iron and the remainder aluminum.
  • the steel flat products thus obtained and coated are annealed at a heating temperature of more than 700 °C. During this annealing process, the protective coating melts and the protective coating is alloyed through. Here, iron diffuses from the steel substrate into the protective coating, so that phases are formed that have a higher temperature stability. The melted protective coating thus solidifies.
  • a solidified, temperature-stable protective coating is a prerequisite for the subsequent forming step.
  • the flat steel product is placed in a press-forming tool, hot-formed into the steel component and cooled so quickly that a hardened structure is created in the steel substrate of the flat steel product.
  • the AISi coating described has the disadvantage that, in comparison to uncoated material, long annealing times are required for thorough alloying.
  • the object of the present invention is therefore to provide a hot-formed flat steel product that can be further processed in a shorter time.
  • a steel flat product for hot forming which consists of a steel substrate consisting of a steel containing 0.1-3% by weight Mn and optionally up to 0.01% by weight B, and a Steel substrate applied protective coating based on Al.
  • the non-ferrous mass fraction of additional alloy components of the protective coating is optionally up to 10% in total.
  • the non-ferrous mass fraction of the protective coating of Mg as an additional alloy component is less than 2.50% Mg, preferably less than 1.50%, in particular the proportion is 0.10-0.50% Mg of the protective coating of Mn as an additional alloy component in total more than 0.30% Mn, preferably more than 0.60% Mn, particularly preferably more than 0.80% Mn.
  • the non-ferrous mass fraction of the protective coating of Si as an additional alloy component is less than 1.80% Si, preferably less than 1.20% Si, preferably less than 0.80% Si, particularly preferably less than 0.60% Si.
  • an iron-free mass fraction of an alloy component in the protective coating is understood to mean the fraction of the total mass of this alloy component in the total mass of all elements in the protective coating except iron.
  • the protective coating thus comprises a proportion of up to 2.5% by weight magnesium, more than 0.30% by weight manganese and less than 1.80% by weight silicon based on the total mass of all elements except iron in the protective coating .
  • Using the non-ferrous mass fraction to characterize the protective coating has the advantage that the numerical values do not change as a result of iron diffusing in from the steel substrate.
  • Magnesium has proven to be an advantageous, additional alloying component, which can be easily alloyed into Al protective coatings of the type in question here.
  • the amount of Mg added is adjusted in such a way that the total iron-free mass fraction of magnesium is less than 2.50%, in particular less than 1.50%.
  • the non-ferrous mass fraction of magnesium in the protective coating is preferably at least 0.10% and at most 0.50% Mg, with Mg contents of less than 0.50%, in particular less than 0.45% or up to 0.40% or up to 0.35%, have proven to be particularly favorable in practice.
  • the small amounts of magnesium added to the Al coating are characterized by a higher affinity for oxygen than the main component, aluminum, of the protective coating. Even with the presence of such small amounts of magnesium, a thin oxide layer forms on the surface of the protective coating, covering the aluminum lying between it and the steel substrate. During the heating required for hot forming of the flat steel product, this thin layer prevents the aluminum from reacting with the moisture present in the atmosphere of the furnace used for heating the flat steel product.
  • alloying magnesium reduces the amount of hydrogen entering the steel substrate. If a very high local concentration of hydrogen is reached, this weakens the bond at the grain boundaries of the steel substrate structure to such an extent that a crack occurs along the grain boundary during use as a result of the resulting stress.
  • the layer thickness of the protective coating is typically in the range of 5-35 ⁇ m, in particular 10-25 ⁇ m.
  • the faster alloying of the protective coating has several advantages.
  • the duration of the hot forming process can be shortened, which makes the production process more efficient.
  • energy savings can be achieved through the shortened annealing time.
  • other furnaces can also be used for heating and keeping at the heating temperature.
  • Roller hearth furnaces for example, are used for this process step.
  • shorter roller hearth furnaces can be used because of the shortened annealing time.
  • furnaces that were originally designed for the process security of uncoated material can be used.
  • the nonferrous mass fraction of the protective coating of Mn as an additional alloy component is more than 1.00% Mn, in particular more than 1.30% Mn. It has been shown that from a non-ferrous mass fraction of 1.00% manganese, the annealing time is significantly reduced.
  • a special design variant of the steel flat product is characterized in that the non-ferrous mass fraction of the protective coating of Mn as an additional alloy component is less than 1.80% manganese, preferably less than 1.60% manganese.
  • the non-ferrous mass fraction of the protective coating of Mn as an additional alloy component is less than 1.80% manganese, preferably less than 1.60% manganese.
  • the melting point increases, making the protective coating more difficult to apply by hot dip coating.
  • high manganese levels promote Slag formation in the melt and are therefore also disadvantageous.
  • the exemplary embodiments shown with 1.60% manganese have the advantages according to the invention, they exhibited major slag problems, which made production difficult.
  • the ironless mass fraction of the protective coating of Si as an additional alloy component is less than 1.50% Si, in particular less than 1.00% Si, preferably less than 0.80% Si.
  • melts with a silicon content well below 0.50% are technically difficult to implement, since contamination with silicon is difficult to avoid.
  • the silicon content is therefore in particular more than 0.03%, preferably 0.05%, in particular 0.10%. With these silicon contents, the effect according to the invention still occurs significantly, but the coating process can be implemented much more cost-effectively, since it is not necessary to pay so much attention to silicon impurities.
  • the Al-based protective coating can be applied to the flat steel product particularly economically by hot-dip coating, also known as "hot-dip aluminizing" in technical jargon.
  • the object according to the invention is also achieved by a steel component produced by hot-press forming a flat steel product as described above.
  • the steel component comprises in particular a steel substrate consisting of a steel containing 0.1-3% by weight Mn and optionally up to 0.01% by weight B, and a protective coating based on Al applied to the steel substrate.
  • the non-ferrous mass fraction of additional alloy components of the protective coating is optionally up to 10% in total.
  • the non-ferrous mass fraction of the protective coating of Mg as an additional alloy component is less than 2.5% Mg in total.
  • the non-ferrous mass fraction of the protective coating of Mn as an additional alloy component is more than 0.30% Mn in total.
  • the non-ferrous mass fraction of the protective coating of Si as an additional alloying component is less than 1.80% Si in total.
  • the steel component has the same advantages that are explained above in relation to the flat steel product.
  • preferred non-ferrous mass fractions of the various elements eg manganese, silicon and magnesium are mentioned. These preferred non-ferrous mass fractions with their advantages also apply to the steel component.
  • Hot dip coating also called “hot-dip aluminizing" in technical jargon, is a particularly economical process for applying a protective coating.
  • a melt consisting of aluminum with an optional admixture of up to 10% non-ferrous mass fraction of additional alloy components.
  • the non-ferrous mass fraction of magnesium as an additional alloy component in the melt is less than 2.50% magnesium in total.
  • the non-ferrous mass fraction of manganese as an additional alloy component in the melt totals more than 0.30% manganese and the non-ferrous mass fraction of silicon as an additional alloy component in the melt totals less than 1.80% silicon.
  • Hot-dip coating results in the protective coating being made up of an alloy layer which adjoins the steel substrate and a top layer which adjoins the alloy layer.
  • the composition of the top layer essentially corresponds to the composition of the melt, whereas the alloy layer already contains an iron content of typically more than 30% by weight, since the steel substrate and the adjacent melt mix during the hot dipping process. Because the steel substrate essentially comprises iron, this mixing in the alloy layer does not change the iron-free mass fractions. The melt and the protective coating therefore have the same non-ferrous mass fractions of the alloying elements.
  • the layer thickness of the protective coating is typically in the range of 5-35 ⁇ m, in particular 10-25 ⁇ m.
  • preferred non-ferrous mass fractions of the various elements e.g. manganese, silicon and magnesium
  • These preferred non-ferrous mass fractions and their advantages also apply to the process for producing the flat steel product and in particular to the composition of the melt if production is carried out by means of hot-dip coating.
  • the steel flat product is pre-alloyed immediately after coating by being kept at a pre-alloying temperature of 500°C-600°C for a pre-alloying time of 15-30 seconds.
  • pre-alloying temperature 500°C-600°C for a pre-alloying time of 15-30 seconds.
  • intermediately is to be understood as meaning that the flat steel product does not cool after coating until the protective coating has completely solidified. In practice, depending on the design of the coating system, there can be up to 10 seconds between coating and pre-alloying.
  • the pre-alloying step leads to increased diffusion, so that iron is already diffusing from the substrate into the protective coating and increased iron-containing phases are beginning to form there.
  • the subsequent annealing process for the through-alloying can be further shortened.
  • the manganese content alone shortens the annealing time in the annealing process (see below).
  • the master alloy enables this annealing time to be shortened even further.
  • the annealing of the steel flat product in a furnace preheated to a temperature T for an annealing time t defined by a polygon ABCD is to be understood within the meaning of this application that the value pair of temperature T and annealing time t is within the polygon formed by the points ABCD becomes.
  • the points AH shown have the following pairs of values: designation Temperature [°C] Glow time t [minutes] A 930 1.5 B 930 7 C 880 12 D 880 2.5 E 940 2.5 f 940 9 G 900 13 H 900 4
  • Thickness d [mm] Temperature [°C] Glow time [minutes] 0.7-0.9 910-930 1.5-5 0.7-0.9 880-900 2:5-7 1-1.4 910-930 1:8-6 1-1.4 880-900 3-8.5 1.5-1.8 910-930 2:5-7 1.5-1.8 880-900 3.5-10 1:9-2:4 910-930 3.5-10 1:9-2:4 880-900 4-11 2.5-3.5 910-930 4-11 2.5-3.5 880-900 4:5-12
  • the addition of manganese while simultaneously limiting the silicon content accelerates the diffusion process of the iron from the steel substrate into the protective coating, ie the time for full alloying is shortened. Therefore, the annealing time compared to a standard process, such as that in EP2086755 is described, can be significantly shortened.
  • the so-called Fe seam forms in the protective coating.
  • This is a high ferrous phase in the protective coating at the interface with the steel substrate.
  • the thickness of the Fe seam is a measure of the degree of alloying penetration of the protective coating.
  • the thickness of the Fe seam after a certain annealing time is therefore a measure of the alloying penetration rate of the coating.
  • the method is developed in such a way that when the steel flat product is annealed in a furnace that has been preheated to a temperature T for an annealing time t defined by the polygon ABCD figure 11 for flat steel products with a thickness between 0.7mm and 1.5mm or in a furnace preheated to a temperature T for an annealing time t defined by the polygon EFGH figure 11 for flat steel products with a thickness between 1.5 mm and 3.0 mm, an Fe seam results with a thickness greater than 2.5 ⁇ m, in particular greater than 8 ⁇ m, preferably greater than 10 ⁇ m.
  • the thickness of the Fe-seam is adjusted according to the other requirements.
  • a sufficiently thick Fe seam ensures that no liquid phases (e.g.
  • liquid aluminium occur in the protective coating during hot forming.
  • the more rapid alloying causes the surface of the steel flat product to discolour. While the steel flat product shows a shiny, metallic surface before annealing, the surface of the steel flat product is dark and dull after the protective coating has been thoroughly alloyed. The faster the protective coating alloys through, the faster the surface discolours. The dark, matt surface means that the heat coupling is significantly improved. The necessary core temperature for hot forming is therefore also reached more quickly. This results in a self-reinforcing effect of the manganese content according to the invention.
  • the alloying time of the protective coating is reduced.
  • the faster alloying leads to an increased heating rate in the steel substrate and thus to a faster annealing process.
  • the heating temperature is so high that the flat steel product has a hot forming temperature at the start of forming at which the structure of the steel substrate is completely or partially converted into an austenitic structure, and that the flat steel product is quenched after forming or in the course of forming is so that hardened structure is formed in the structure of the steel substrate of the steel flat product.
  • the heating temperature is at least 700°C, in particular 880°C to 950°C.
  • the steel substrate is of a steel containing 0.1-3 wt% Mn and optionally up to 0.01 wt% B.
  • the microstructure of the steel is martensitic by hot working or partially martensitic structure convertible.
  • the microstructure of the steel substrate of the steel component is therefore preferably a martensitic or at least partially martensitic microstructure, since this has a particularly high degree of hardness.
  • the steel substrate is particularly preferably a steel which, in addition to iron and unavoidable impurities (in % by weight), consists of C: 0.04 - 0.45% by weight, Si: 0.02 - 1.2% by weight, Mn: 0.5 - 2.6% by weight, Al: 0.02 - 1.0% by weight, P: ⁇ 0.05% by weight, S: ⁇ 0.02% by weight, N: ⁇ 0.02% by weight, Sn: ⁇ 0.03% by weight As: ⁇ 0.01% by weight Approx: ⁇ 0.005% by weight and optionally one or more of the elements "Cr, B, Mo, Ni, Cu, Nb, Ti, V" in the following contents CR: 0.08-1.0% by weight, B: 0.001 - 0.005% by weight Mon: ⁇ 0.5% by weight Ni: ⁇ 0.5% by weight Cu: ⁇ 0.2% by weight Nb: 0.02 - 0.08% by weight, Ti: 0.01 - 0.08% by weight V: ⁇ 0.1% by weight consists.
  • the elements P, S, N, Sn, As, Ca are impurities that cannot be completely avoided in steel production. In addition to these elements, you can also other elements may be present as impurities in the steel. These other elements are summarized under the "unavoidable impurities".
  • the total content of unavoidable impurities is preferably not more than 0.2% by weight, preferably not more than 0.1% by weight.
  • the optional alloying elements Cr, B, Nb, Ti, for which a lower limit is given, can also occur in contents below the respective lower limit as unavoidable impurities in the steel substrate. In that case, they are also counted among the unavoidable impurities, the total content of which is limited to a maximum of 0.2% by weight, preferably a maximum of 0.1% by weight.
  • the individual upper limits for the respective contamination of these elements are preferably as follows: CR: ⁇ 0.050% by weight, B: ⁇ 0.0005% by weight Nb: ⁇ 0.005% by weight, Ti: ⁇ 0.005% by
  • the carbon content of the steel is at most 0.37% by weight and/or at least 0.06% by weight. In particularly preferred variants, the C content is in the range from 0.06 to 0.09% by weight or in the range from 0.12 to 0.25% by weight or in the range from 0.33 to 0.37% by weight %.
  • the Si content of the steel is at most 1.00% by weight and/or at least 0.06% by weight.
  • the Mn content of the steel is at most 2.4% by weight and/or at least 0.75% by weight. In particularly preferred embodiment variants, the Mn content is in the range of 0.75-0.85% by weight or in the range of 1.0-1.6% by weight.
  • the Al content of the steel is at most 0.75% by weight, in particular at most 0.5% by weight, preferably at most 0.25% by weight.
  • the Al content is preferably at least 0.02%.
  • the sum of the contents of Si and Al (usually referred to as Si+Al) is therefore at most 1.5% by weight, preferably at most 1.2% by weight. Additionally or alternatively, the sum of the contents of Si and Al is at least 0.06% by weight, preferably at least 0.08% by weight.
  • the elements P, S, N are typical impurities that cannot be completely avoided in steel production.
  • the maximum P content is 0.03% by weight.
  • the S content is preferably at most 0.012%.
  • the N content is preferably at most 0.009% by weight.
  • the steel also contains chromium with a content of 0.08 - 1.0% by weight.
  • the Cr content is preferably at most 0.75% by weight, in particular at most 0.5% by weight.
  • the sum of the chromium and manganese contents is preferably limited.
  • the total is at most 3.3% by weight, in particular at most 3.15% by weight.
  • the sum is at least 0.5% by weight, preferably at least 0.75% by weight.
  • the steel preferably also optionally contains boron with a content of 0.001-0.005% by weight.
  • the B content is at most 0.004% by weight.
  • the steel can optionally contain molybdenum with a content of at most 0.5% by weight, in particular at most 0.1% by weight.
  • the steel can optionally contain nickel with a content of at most 0.5% by weight, preferably at most 0.15% by weight.
  • the steel can also contain copper with a content of at most 0.2% by weight, preferably at most 0.15% by weight.
  • the steel can optionally contain one or more of the micro-alloying elements Nb, Ti and V.
  • the optional Nb content is at least 0.02% by weight and at most 0.08% by weight, preferably at most 0.04% by weight.
  • the optional Ti content is at least 0.01% by weight and at most 0.08% by weight, preferably at most 0.04% by weight.
  • the optional V content is at most 0.1% by weight, preferably at most 0.05% by weight.
  • the sum of the contents of Nb, Ti and V is preferably limited.
  • the total is at most 0.1% by weight, in particular at most 0.068% by weight. Furthermore, the sum is preferably at least 0.015% by weight.
  • the steel substrate is a steel from the group of steels A-E, the chemical analysis of which is given in Table 2.
  • Table 2 is to be understood in such a way that for each steel from the group of steels A-E the element proportions are given in percent by weight. A minimum and a maximum weight percentage is given here.
  • steel A therefore has a carbon content C: 0.05% by weight-0.10% by weight.
  • FIGS 1-4 show cross-section images of steel components that were produced with the same steel substrate and with the same forming process. Only the composition of the protective coating was varied.
  • Shaped blanks were cut from a 1.5 mm thick strip of steel grade D according to Table 2 with a 25 ⁇ m thick aluminum-based protective coating on both sides. Both a punching tool and a laser were used as cutting methods.
  • the detailed chemical composition of the substrate was C: 0.223 wt%, Si: 0.294 wt%, Mn: 1.275 wt%, P: 0.008 wt%, S: 0.002 wt%, Al: 0.046 wt%, Cr: 0.181 wt%, Cu: 0.054 wt%, Mo: 0.001 wt%, N: 0.001 wt%, Ni: 0.035 wt%, Nb: 0.002 wt% -%, Ti: 0.033 wt%, V: 0.007 wt%, B: 0.0033 wt%, Sn: 0.002 wt%.
  • Table 1 shows the thickness of the Fe seam for different variants of the non-ferrous mass fractions of the elements Mg, Mn and Si and for different annealing times t.
  • the Figures 1-4 show examples of cross-sections of the steel component produced in this way with different compositions.
  • the Figures 5-8 show diagrams used to explain the various effects.
  • figure 1 shows a steel component 21 with a protective coating 15 based on aluminum on a steel substrate 13.
  • the protective coating 15 was applied by hot dip coating.
  • the melt consisted of aluminum with an additional alloy of 0.4% by weight Mg, 0.8% by weight Mn and 2.0% by weight Si.
  • the steel flat product 11 accordingly had a protective coating 15 with a thickness of 25 ⁇ m after the coating, the protective coating 15 having an iron-free mass fraction of 0.4% Mg, 0.8% Mn and 2.0% Si.
  • the steel component 21 shown in the cross section with the protective coating 15 based on aluminum resulted, the protective coating 15 having an iron-free mass fraction of 0.4% Mg, 0.8% Mn and 2.0% Si.
  • FIG 2 shows a steel component 21 with a protective coating 15 based on aluminum on a steel substrate 13.
  • the protective coating 15 was applied by hot dip coating.
  • the melt consisted of aluminum with an additional alloy of 0.4% by weight Mg, 1.6% by weight Mn and 2.0% by weight Si.
  • the steel flat product 11 accordingly had a protective coating 15 with a thickness of 25 ⁇ m after the coating, the protective coating 15 having an iron-free mass fraction of 0.4% Mg, 0.8% Mn and 2.0% Si.
  • the steel component 21 shown in the cross-section resulted with the protective coating 15 based on aluminum, the protective coating 15 having an iron-free mass fraction of 0.4% Mg, 1.6% Mn and 2.0% Si.
  • the two steel components 21 in Figure 1 and Figure 2 only show hints of an Fe-fringe.
  • the thickness of the Fe seam is less than 1 ⁇ m.
  • the protective coating 15 is therefore not sufficiently alloyed in the 3 minutes at 920°C.
  • FIG 3 shows a steel component 21 with a protective coating 15 based on aluminum on a steel substrate 13.
  • the protective coating 15 was applied by hot dip coating.
  • the melt consisted of aluminum with an additional alloy of 0.4% by weight Mg and 0.8% by weight Mn. Apart from impurities in the range of 0.2% by weight, the melt contained no silicon.
  • the steel flat product 11 (see figure 12 ) accordingly had a protective coating 15 with a thickness of 25 ⁇ m after the coating, the protective coating 15 having an ironless mass fraction 0.4% Mg, 0.8% Mn and less than 0.50% Si.
  • the steel component 21 shown in the cross section image resulted with the protective coating 15 based on aluminum, the protective coating 15 having an iron-free mass fraction of 0.4% Mg, 0.8% Mn and less than 0.50% Si.
  • FIG 4 shows a steel component 21 with a protective coating 15 based on aluminum on a steel substrate 13.
  • the protective coating 15 was applied by hot dip coating.
  • the melt consisted of aluminum with an additional alloy of 0.4% by weight Mg and 1.6% by weight Mn. Apart from impurities in the range of 0.2% by weight, the melt contained no silicon. Accordingly, after the coating, the flat steel product had a protective coating 15 with a thickness of 25 ⁇ m, the protective coating 15 having an iron-free mass fraction of 0.4% Mg, 1.6% Mn and less than 0.50% Si.
  • the steel component 21 shown in the cross section with the aluminum-based protective coating resulted, the protective coating 15 having an iron-free mass fraction of 0.4% Mg, 1.6% Mn and less than 0.50% Si.
  • figure 7 shows the thickness of the Fe seam with an annealing time of 3 minutes as a function of the non-ferrous mass fraction of manganese.
  • the ironless mass fraction of silicon is about 0.2%. From an iron-free mass fraction of manganese of about 0.3%, a thicker Fe rim results, with the thickness of the Fe rim increasing with the manganese content.
  • figure 8 shows the effects of silicon.
  • the thickness of the Fe seam with an annealing time of 3 minutes is plotted as a function of the non-ferrous mass fraction of silicon.
  • the non-ferrous mass fraction of manganese was 1.6%. Below 1.8% silicon, the manganese effect is still significant, with the smaller the massless fraction of silicon, the greater the effect.
  • figure 10 shows the thickness of the Fe seam as a function of the annealing time for the same layer compositions as in figure 9 .
  • pre-alloying was carried out before annealing, in which the mold blanks were held at a pre-alloying temperature of 680 °C for a pre-alloying time of 13 seconds.
  • the Fe seam forms much earlier and is thicker than without a master alloy for the same annealing time.
  • the manganese effect can be seen that a significant Fe fringe forms faster with manganese alloying. This is the case with both 0% Si and 0.5% silicon.
  • figure 12 shows a schematic representation of a steel flat product 11 for hot forming, which consists of a steel substrate 13, which consists of a steel that has 0.1-3% by weight Mn and optionally up to 0.01% by weight B, and a protective coating 15 applied to the steel substrate 13 based on Al.
  • a steel flat product 11 for hot forming which consists of a steel substrate 13, which consists of a steel that has 0.1-3% by weight Mn and optionally up to 0.01% by weight B, and a protective coating 15 applied to the steel substrate 13 based on Al.
EP21175294.4A 2021-05-21 2021-05-21 Produit plan en acier doté d'un revêtement al, son procédé de fabrication, composant en acier et son procédé de fabrication Withdrawn EP4092141A1 (fr)

Priority Applications (4)

Application Number Priority Date Filing Date Title
EP21175294.4A EP4092141A1 (fr) 2021-05-21 2021-05-21 Produit plan en acier doté d'un revêtement al, son procédé de fabrication, composant en acier et son procédé de fabrication
PCT/EP2022/063495 WO2022243397A1 (fr) 2021-05-21 2022-05-18 Produit en acier plat doté de revêtement en al, procédé de production associé, élément en acier et procédé de production associé
CN202280036669.9A CN117355620A (zh) 2021-05-21 2022-05-18 具有铝涂层的扁钢产品、其生产方法、钢构件及其生产方法
EP22729619.1A EP4341454A1 (fr) 2021-05-21 2022-05-18 Produit en acier plat doté de revêtement en al, procédé de production associé, élément en acier et procédé de production associé

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EP21175294.4A EP4092141A1 (fr) 2021-05-21 2021-05-21 Produit plan en acier doté d'un revêtement al, son procédé de fabrication, composant en acier et son procédé de fabrication

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EP22729619.1A Pending EP4341454A1 (fr) 2021-05-21 2022-05-18 Produit en acier plat doté de revêtement en al, procédé de production associé, élément en acier et procédé de production associé

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Citations (7)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JPS5623265A (en) * 1979-08-01 1981-03-05 Nisshin Steel Co Ltd Hot dip aluminized steel excellent in corrosion
JPH05171393A (ja) * 1991-12-26 1993-07-09 Sumitomo Metal Ind Ltd 耐湿食性に優れた溶融Ａｌ系めっき鋼材
EP1219719A1 (fr) * 2000-12-25 2002-07-03 Nisshin Steel Co., Ltd. Tôle d'acier inoxydable ferritique avec une bonne aptitude et procédé pour sa fabrication
EP0971044B1 (fr) 1998-07-09 2003-05-14 Sollac Tole d'acier laminée à chaud et à froid revêtue et présentant une très haute résistance après traitement thermique
EP2086755A1 (fr) 2006-10-30 2009-08-12 ArcelorMittal France Bandes d'acier revêtu, procédés pour leur fabrication, procédés pour leur utilisation, ébauches d'estampage préparées pour elles, produits estampés préparés pour elles, et articles de fabrication qui contiennent ce genre de produit estampé
EP2993248A1 (fr) * 2014-09-05 2016-03-09 ThyssenKrupp Steel Europe AG Produit plat en acier doté d'un revêtement Al, son procédé de fabrication, élément en acier et son procédé de fabrication
CN111575622A (zh) * 2020-05-11 2020-08-25 马鞍山钢铁股份有限公司 一种具有优异涂装性能的热成形零部件用的镀铝钢板及其制造方法及热成形零部件

Patent Citations (7)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JPS5623265A (en) * 1979-08-01 1981-03-05 Nisshin Steel Co Ltd Hot dip aluminized steel excellent in corrosion
JPH05171393A (ja) * 1991-12-26 1993-07-09 Sumitomo Metal Ind Ltd 耐湿食性に優れた溶融Ａｌ系めっき鋼材
EP0971044B1 (fr) 1998-07-09 2003-05-14 Sollac Tole d'acier laminée à chaud et à froid revêtue et présentant une très haute résistance après traitement thermique
EP1219719A1 (fr) * 2000-12-25 2002-07-03 Nisshin Steel Co., Ltd. Tôle d'acier inoxydable ferritique avec une bonne aptitude et procédé pour sa fabrication
EP2086755A1 (fr) 2006-10-30 2009-08-12 ArcelorMittal France Bandes d'acier revêtu, procédés pour leur fabrication, procédés pour leur utilisation, ébauches d'estampage préparées pour elles, produits estampés préparés pour elles, et articles de fabrication qui contiennent ce genre de produit estampé
EP2993248A1 (fr) * 2014-09-05 2016-03-09 ThyssenKrupp Steel Europe AG Produit plat en acier doté d'un revêtement Al, son procédé de fabrication, élément en acier et son procédé de fabrication
CN111575622A (zh) * 2020-05-11 2020-08-25 马鞍山钢铁股份有限公司 一种具有优异涂装性能的热成形零部件用的镀铝钢板及其制造方法及热成形零部件

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