WO2023246939A1 - 一种高强度高成形冷轧热镀纯锌带钢及其制造方法 - Google Patents

一种高强度高成形冷轧热镀纯锌带钢及其制造方法 Download PDF

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WO2023246939A1
WO2023246939A1 PCT/CN2023/102174 CN2023102174W WO2023246939A1 WO 2023246939 A1 WO2023246939 A1 WO 2023246939A1 CN 2023102174 W CN2023102174 W CN 2023102174W WO 2023246939 A1 WO2023246939 A1 WO 2023246939A1
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strength
hot
dip
pure zinc
rolled hot
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PCT/CN2023/102174
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English (en)
French (fr)
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王俊峰
朱晓东
吴张炜
郑韬
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宝山钢铁股份有限公司
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Publication of WO2023246939A1 publication Critical patent/WO2023246939A1/zh

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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
    • 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
    • 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
    • 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
    • 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
    • C21D9/52—Heat treatment, e.g. annealing, hardening, quenching or tempering, adapted for particular articles; Furnaces therefor for wires; for strips ; for rods of unlimited length
    • 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
    • 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
    • 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
    • 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
    • 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
    • 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
    • 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
    • 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
    • C22C38/28—Ferrous alloys, e.g. steel alloys containing chromium with titanium or zirconium
    • 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
    • C22C38/38—Ferrous alloys, e.g. steel alloys containing chromium with more than 1.5% by weight of manganese
    • 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
    • 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
    • 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
    • C23C2/34—Hot-dipping or immersion processes for applying the coating material in the molten state without affecting the shape; Apparatus therefor characterised by the shape of the material to be treated
    • C23C2/36—Elongated material
    • C23C2/40—Plates; Strips

Definitions

  • the present invention relates to a steel material and a manufacturing method thereof, in particular to a hot-dip galvanized steel and a manufacturing method thereof.
  • galvanized dual-phase steel Compared with cold-rolled dual-phase steel, galvanized dual-phase steel has very excellent corrosion resistance and is mostly used to prepare car body structural parts and reinforcements. However, as the design of car body structural parts becomes more and more complex, the market and operators have put forward higher requirements for the formability of steel plates. The traditional hot-dip galvanized dual-phase steel currently used has gradually been unable to meet the design of some car body structures. need.
  • TRIP steel or TWIP steel If TRIP steel or TWIP steel is used, its elongation is too excessive and its alloy content is high, which will cause corresponding waste and reduce manufacturability.
  • traditional QP steel and TBF steel can meet the formability requirements of complex parts and have low alloy costs, their excessive Si content reduces manufacturability and weldability, limiting their applications.
  • the publication number is CN105506513A
  • the publication date is April 20, 2016,
  • the Chinese patent document titled "Ultra-high-strength cold-rolled automotive steel and its preparation method” discloses an ultra-high-strength cold-rolled automotive steel and Its production method, its typical composition is 0.6C-4.5Mn-3Si-5Al, by controlling the hot rolling process and continuous retreat process, the material obtains excellent strong plasticity, its tensile strength is greater than 1180MPa, and the elongation is not less than 18%.
  • the addition of large amounts of C, Si, and Mn significantly increases the manufacturing difficulty and cost.
  • Literature discloses a cold-rolled high-strength steel plate with excellent phosphating performance and formability and its manufacturing method. Its typical composition is 0.2C-2.5Mn-1.5Si. Through controlled rolling, controlled cooling and continuous annealing, the structure can be It contains no less than 5% retained austenite, its tensile strength is ⁇ 1180MPa, and its elongation is ⁇ 14%.
  • the chemical element composition of the steel plate is mainly designed to be C, Si, and Mn, it still has a high Si content, which is not conducive to the subsequent production and spot welding performance of hot-dip galvanized products.
  • the publication number is CN102021482A
  • the publication date is April 20, 2011,
  • the Chinese patent document titled "A cold-rolled hot-dip galvanized dual-phase steel and its manufacturing method” discloses a 1180MPa grade cold-rolled hot-dip steel Galvanized dual-phase steel and its manufacturing method, its typical composition is 0.12C-2.0Mn-(0.6 ⁇ 1.4)Si-0.5Cr-0.2Mo.
  • the low alloy content ensures that the material has good manufacturability and weldability. It can obtain a tensile strength of 1180MPa through conventional DP steel manufacturing processes.
  • the microstructure of the steel plate is a ferrite + martensite dual-phase structure, its deformation ability is limited, and the elongation of the material is not high.
  • high contents of Cr and Mo elements are added to the steel, which not only increases the alloy cost, but is also detrimental to the surface quality of galvanized sheets.
  • One of the purposes of the present invention is to provide a high-strength, high-form cold-rolled hot-dip galvanized steel that, through reasonable composition matching and process design, can achieve the features of traditional dual-phase steel.
  • retained austenite is further introduced to greatly increase the uniform elongation of the material and broaden the formability of galvanized steel under similar strength.
  • This high-strength and high-forming cold-rolled hot-dip galvanized steel has a yield strength of 780 to 1030MPa, a tensile strength of ⁇ 1180MPa, and an elongation of A 50 ⁇ 11%. It has excellent weldability and formability and can be effectively used to prepare automobile structural parts. , anti-collision parts and other parts, which have good promotion prospects and application value.
  • the present invention provides a cold-rolled hot-dip galvanized steel, which includes a substrate and a zinc coating coated on the substrate, wherein the substrate contains Fe and inevitable impurity elements, and the substrate also contains
  • the mass percentages of the following chemical elements are as follows:
  • the matrix of the microstructure of the substrate includes retained austenite with a volume fraction of 5% to 15%, and the microstructure also includes carbide precipitates with a size less than 80 nm.
  • the size of the carbide precipitate phase refers to its particle size.
  • the volume fraction of retained austenite in the matrix of the microstructure of the substrate is 5%, 6%, 7%, 8%, 9%, 10%, 11%, 12%, 13%, 14%, 15%, or any two of the above values.
  • the particle size of the carbide precipitate phase is 10 nm, 20 nm, 30 nm, 40 nm, 50 nm, 60 nm, 70 nm, 80 nm, or within the range of any two of the above values, such as 30 to 70 nm.
  • the matrix of the microstructure of the substrate includes ferrite, tempered martensite lath, bainite, and retained austenite.
  • the mass percentage of each chemical element of the substrate is:
  • the cold-rolled hot-dip galvanized steel of the present invention has high strength and high formability, as shown in the yield strength of 780 to 1030MPa, the tensile strength of ⁇ 1180MPa, and the elongation A50 ⁇ 11%.
  • the inventor has carried out a completely new design of the chemical composition.
  • the stability of the austenite of the steel can be effectively improved while reducing the alloying elements such as Cr and Mo.
  • the usage amount can not only effectively reduce costs, but also improve the deterioration of steel welding performance caused by carbonization, while ensuring a certain degree of manufacturability.
  • C In the high-strength and high-forming cold-rolled hot-dip pure zinc strip steel of the present invention, C is an important component element in the hot-dip galvanized steel, which directly affects the strong plasticity of the galvanized sheet.
  • the austenite content formed during annealing in the critical zone will decrease, and the austenite stability and martensite hardenability will decrease, making it difficult to ensure strong plasticity; at the same time, the austenite content in the steel will decrease.
  • the content of C element should not be too high.
  • the mass percentage content of C element is controlled between 0.15% and 0.25%.
  • the Mn element can improve the stability of austenite and shift the C curve to the right, thereby reducing the critical cooling rate of martensite.
  • the Mn element content in steel should not be too low. When the Mn content is too low, the hardenability of the steel will be reduced and the strengthening effect will be weakened. At the same time, excessive Mn should not be added to the steel. When the Mn element content in the steel is too high, it will Affects the weldability of the substrate and the quality of surface galvanizing.
  • the mass percentage of the Mn element is controlled between 2.2 and 3.0%, for example, 2.4 %, 2.6%, 2.8%.
  • Si is a ferrite solid solution strengthening element, which can strongly improve the strength of the steel plate.
  • Si element can also promote the enrichment of C atoms from ferrite to austenite, purify ferrite, and improve the stability of austenite.
  • the Si element content in steel should not be too high. Too high a content of Si element will directly affect the plateability and spot weldability of the substrate. Therefore, in order to exert the beneficial effects of Si element, the content of Si element in steel must be strictly controlled.
  • the mass percentage content of Si element is controlled at 0.3 ⁇ 0.9%, such as 0.4%, 0.5%, 0.6%, 0.7%, 0.8%.
  • the role of the Al element is similar to that of the Si element, which can effectively inhibit the precipitation of carbides and promote the diffusion of carbon elements into austenite; and
  • the Al element can also increase the stacking fault energy of austenite and improve the stability of austenite.
  • the Al added to steel can also pin the grain boundaries and refine the grains by forming AlN.
  • the content of Al element in the steel should not be too high.
  • the mass percentage of the Al element is controlled between 0.1 and 0.5%, such as 0.2%. , 0.3%, 0.4%.
  • Ti In the high-strength and high-forming cold-rolled hot-dip pure zinc strip steel of the present invention, Ti combines with C and N to form Ti(C,N), TiN and TiC, which can refine the cast structure and It can hinder grain coarsening during hot processing.
  • the Ti element content in steel should not be too high. Adding excessive Ti will increase the cost and increase the content and size of the above-mentioned precipitates, thereby reducing the ductility of the steel plate.
  • the mass percentage of Ti element needs to be controlled between 0.01% and 0.1%, such as 0.02%, 0.04%, 0.06%, and 0.08%. In some embodiments, the mass percentage of Ti element is controlled between 0.01% and 0.08%.
  • Nb In the high-strength and high-forming cold-rolled hot-dip pure zinc strip steel of the present invention, the Nb element will strongly inhibit dynamic recrystallization. It can effectively inhibit dynamic recrystallization by combining with C and N to form Nb (C, N). During the hot working process, the grains are coarsened and the ferrite grains are refined. The addition of Nb and Ti will significantly refine the austenite structure of the matrix. The fine austenite grain size is more stable and has excellent thermal stability and mechanical stability. However, it should be noted that the Nb element content in steel should not be too high. Adding excessive Nb will deteriorate the hot working performance of the steel and the toughness of the steel plate.
  • the mass percentage of the Nb element is controlled between 0.01% and 0.1%, such as 0.02%, 0.04%, 0.06%, and 0.08%. In some embodiments, the mass percentage of Nb element is controlled between 0.01% and 0.07%.
  • Cr In the high-strength and high-forming cold-rolled hot-dip pure zinc strip steel of the present invention, Cr can effectively refine the grain structure and inhibit grain coarsening during hot processing, and Cr is a ferrite-forming element. It can promote the diffusion of C into austenite, improve the stability of austenite, and reduce the critical cooling rate during annealing.
  • the Cr element content in steel should not be too high. Excessive Cr content will destroy the ductility and surface plating properties of the steel. For this reason, the content of Cr element in steel must be strictly controlled. In the present invention, the mass percentage content of Cr element is controlled between 0.01% and 0.3%, such as 0.02%, 0.05%, 0.1%, 0.15%, and 0.2%. ,0.25%.
  • the chemical elements of the substrate also include at least one of the following items: Mo: 0.02 to 0.2%, V: 0.005 ⁇ 0.2%, Cu: 0.003 ⁇ 0.5%, B: 0.0005 ⁇ 0.003%.
  • Mo, V, Cu, and B elements can be further added to the steel.
  • Mo In the present invention, the role of Mo element is similar to that of Cr. It can shift the C curves of pearlite and bainite to the right and effectively improve the hardenability of steel; at the same time, Mo element can also strengthen and precipitate through solid solution Strengthening significantly increases strength without affecting the quality of surface galvanizing. However, the Mo element is expensive and should not be added excessively considering the production cost. Therefore, in the high-strength and high-forming cold-rolled hot-dip pure zinc strip steel of the present invention, the mass percentage of the Mo element is controlled to 0.02 to 0.02%. Between 0.2%, such as 0.05%, 0.1%, 0.15%.
  • V In the present invention, V mainly exists in the form of VC in hot-dip galvanized steel, through which grain boundaries are pinned. Refine grains and disperse precipitation strengthening in ferrite to improve the strength and toughness of steel. At the same time, the refinement of grains improves the thermal stability and mechanical stability of austenite, which is beneficial to the improvement of strong plasticity. However, adding the V element will further increase the alloy cost of the steel. Therefore, in the high-strength and high-forming cold-rolled hot-dip pure zinc strip steel of the present invention, the mass percentage of the V element is controlled between 0.005 and 0.2%. time, such as 0.01%, 0.03%, 0.05%, 0.1%, 0.15%.
  • Cu is an austenite stabilizing element, which can hinder the coarsening of grains at high temperatures and is conducive to obtaining a certain amount of austenite in the structure; at the same time, during the galvanizing process, the Cu element will ⁇ -Cu precipitates, thereby effectively improving the strength of steel.
  • the Cu element content in the steel should not be too high. If the Cu content is too high, it will have an adverse effect on the hot deformation process. Therefore, in the high-strength and high-formation cold-rolled hot-dip pure zinc strip steel of the present invention, the Cu element The mass percentage is controlled between 0.003% and 0.5%, such as 0.005%, 0.01%, 0.05%, 0.1%, 0.2%, and 0.4%.
  • the B element can hinder the recrystallization of the steel during the hot rolling process and is conducive to the refinement of the microstructure caused by the accumulated deformation.
  • the B element content in the steel should not be too high. Adding excessive B will generate BC and reduce the ductility of the steel. Therefore, in the high-strength and high-forming cold-rolled hot-dip pure zinc strip steel of the present invention, the B element The mass percentage is controlled between 0.0005% and 0.003%, such as 0.001%, 0.0015%, 0.002%, and 0.0025%.
  • the mass percentage content of each chemical element in the substrate satisfies: Si+Al+Cr ⁇ 1.2%.
  • the present invention can further control the element ratio in steel, and make the mass percentage content of Si, Al and Cr satisfy: Si+Al +Cr ⁇ 1.2%.
  • Si+Al+Cr ⁇ 1.2% it not only ensures better manufacturability of the steel plate, but also promotes the distribution of carbon from martensite to austenite, which is beneficial to improving the plasticity of the steel plate.
  • the mass percentages of Si, Al, and Cr satisfy: Si+Al+Cr is 0.4%, 0.5%, 0.6%, 0.7%, 0.8%, 0.9%, 1.0%, 1.1%, 1.2% or within the range of any two of the above values. In some embodiments, the mass percentages of Si, Al, and Cr satisfy: 0.6% ⁇ Si+Al+Cr ⁇ 1.2%
  • the mass percentage content of P, S, and N among the unavoidable impurities in the substrate satisfies: P ⁇ 0.02%, S ⁇ 0.01%, N ⁇ 0.008%.
  • P, S, and N elements are all impurity elements in the steel pipe.
  • the content of impurity elements in high-strength and high-forming cold-rolled hot-dip pure zinc strip steel should be reduced as much as possible.
  • the contents of P, S, and N elements in the steel must be strictly controlled and controlled to P ⁇ 0.02%, S ⁇ 0.01%, and N ⁇ 0.008%.
  • the mass percentage content of each chemical element in the substrate satisfies: 3C+Si+6P+8S ⁇ 2.0%.
  • the present invention can further control the content of C, Si elements and impurity elements P and S in steel to satisfy: 3C+Si+6P+8S ⁇ 2.0%.
  • the mass percentages of C, Si, P, and S satisfy: 3C+Si+6P+8S is 0.75%, 0.8%, 1.0%, 1.2%, 1.4%, 1.6%, 1.8%, 2.0 % or within the range of any two of the above values. In some embodiments, the mass percentages of C, Si, P, and S satisfy: 0.8% ⁇ 3C+Si+6P+8S ⁇ 2.0%
  • the matrix of the microstructure of the substrate also includes ferrite, tempered martensite laths and bainite.
  • the mass percentage of C in the retained austenite is ⁇ 0.8%.
  • the mass percentage of C in the retained austenite is 0.8%, 0.9%, 1.0%, 1.1%, 1.2%, 1.3 %, 1.4%, 1.5% or any two of the above values. In some embodiments, in the cold-rolled hot-dip galvanized steel of the present invention, the mass percentage of C in the retained austenite is 0.8 to 1.5%.
  • ⁇ -carbide is distributed in the tempered martensite strip.
  • the carbide precipitated phase and the matrix are in a coherent or semi-coherent state.
  • the thickness of the galvanized layer on one side of the substrate is 5 to 200 ⁇ m, for example, 15 to 185 ⁇ m.
  • the galvanizing process can be used to achieve the high strength and high performance of the present invention.
  • Each side of the base plate forming the cold-rolled hot-dip pure zinc strip is hot-dipped to form a coating with a thickness of 5 to 200 ⁇ m. After the hot-dip is completed, the steel plate is cooled to room temperature.
  • the yield strength is 780-1030MPa
  • the tensile strength is ⁇ 1180MPa
  • the elongation A 50 is ⁇ 11%.
  • the yield strength is 800-1030MPa, or 830-1030MPa, or 780-950MPa.
  • the tensile strength is ⁇ 1200MPa, or 1180-1250MPa.
  • another object of the present invention is to provide a method for manufacturing the above-mentioned high-strength and high-formation cold-rolled hot-dip pure zinc strip.
  • This manufacturing method optimizes the design of the annealing process, which can effectively prepare the above-mentioned high strength of the present invention.
  • Highly formed cold-rolled hot-dip pure zinc strip steel to ensure excellent mechanical properties of the steel.
  • the present invention proposes the above-mentioned manufacturing method of high-strength and high-forming cold-rolled hot-dip pure zinc strip steel, which includes the steps:
  • the preparation of the high-strength and high-forming cold-rolled hot-dip pure zinc strip steel needs to be based on It has experienced the processes of smelting and continuous casting, hot rolling, pickling, cold rolling, hot-dip galvanizing recrystallization annealing process and post-galvanizing cooling process.
  • the inventor optimized the hot-dip galvanizing recrystallization annealing process in step (5).
  • the process parameters of the hot-dip galvanizing recrystallization annealing process are closely related to the steel composition design, which determines the softness inside the galvanized sheet.
  • the inventor adopts the quenching partition annealing process to treat the cold-rolled steel plate, and the process steps of the hot-dip galvanizing recrystallization annealing are as shown in the above steps (a)-(e).
  • step (a) the cold-rolled plate needs to be heated to the soaking temperature T1 at a heating rate V1 and then held for a period of time t1.
  • the matrix structure of the substrate corresponding to the designed composition in the present invention cannot obtain sufficient austenite or The matrix carbides of the steel plate have not yet been completely dissolved to form austenite particles.
  • the soaking temperature T1 is higher than 850°C and the soaking time t1 is longer than 240s, the austenite content in the steel plate after soaking treatment will significantly increase, the austenite C content will significantly decrease, and the austenite formed and ferrite grain coarsening.
  • the above factors will reduce the stability of the austenite in the steel, causing the Ms point to be too high, which in turn will cause the stability of the internal retained austenite of the galvanized steel sheet to decrease, making the subsequent quenching temperature too high.
  • the soaked steel plate needs to be slowly cooled to the intermediate temperature T2 at the cooling rate V2, then immediately cooled to the quenching temperature T3 at the cooling rate V3, and then kept at temperature t3. time, and then heat the steel plate to T4 at a heating rate V4 and keep it warm for a time of t4.
  • T3 Mf+20 ⁇ Ms-30
  • Ms and Mf are respectively the starting temperature and the ending temperature of the austenite in the structure transforming to martensite at the cooling rate V3 at the intermediate temperature T2, and V3>V2.
  • the selection of the slow cooling rate V2 and the intermediate temperature T2 is mainly to avoid the decomposition of the austenite formed by the soaking treatment in the slow cooling section of step (b), so as to facilitate the operation and make the annealing heat treatment smoothly proceed from step (b).
  • the selection of rapid cooling rate V3 requires It is necessary to minimize the decomposition of austenite in the steel plate matrix during the cooling process to ensure that sufficient martensite and bainite are formed at the quenching temperature T3.
  • T3 temperature is too high, the martensite content is insufficient and the strength of the steel is difficult to guarantee; if the T3 temperature is too low, too much martensite is formed and the retained austenite content is insufficient, which has a negative impact on the elongation.
  • T4 temperature can enrich the C in martensite into adjacent austenite, improve the stability of austenite, and at the same time, can further strengthen the matrix with the precipitation of the dispersion strengthening phase.
  • too long a residence time will cause martensite tempering, austenite decomposition and precipitation phase coarsening, thereby deteriorating the strong plasticity of the galvanized sheet.
  • the slab is heated at 1200-1280°C, the holding time is 0.5-5h, and the final rolling temperature is controlled to be ⁇ 850°C (such as 850-940°C). °C or 880 ⁇ 940 °C), the coiling temperature ⁇ 650 °C (such as 520 ⁇ 650 °C or 520 ⁇ 630 °C).
  • step (4) the cold rolling deformation is controlled to be 30-60%, preferably between 35-50%.
  • the temperature of the zinc pot is 450-500°C.
  • the galvanized steel sheet is cooled at a temperature of ⁇ 20°C/s (such as 20-40°C/s or 30-40°C/s). rate to cool to room temperature.
  • the high-strength and high-forming cold-rolled hot-dip pure zinc strip and its manufacturing method according to the present invention have the following advantages and beneficial effects:
  • the high-strength and high-forming cold-rolled hot-dip pure zinc strip steel of the present invention adopts a reasonable chemical composition.
  • the content of C element is appropriately increased and the content of Cr, Mo, etc. is reduced.
  • the content of alloying elements can not only greatly reduce alloy costs, but also effectively improve the manufacturability of steel.
  • This high-strength and high-forming cold-rolled hot-dip pure zinc strip can be produced in the existing high-strength steel continuous annealing production line without major adjustments, and has good prospects for promotion and application.
  • the high-strength and high-forming cold-rolled hot-dip pure zinc strip steel of the present invention adopts reasonable chemical composition, and through the design of the alloy element ratio, the galvanized steel sheet obtains good welding performance.
  • the present invention ensures that the galvanized steel plate has good spot welding performance through low alloy content, especially application restrictions on C, Si, P, and S.
  • the present invention optimizes the design of the preparation process, optimizes and designs a new hot-dip galvanizing recrystallization annealing process, and specifically controls the parameters of each stage.
  • the hard-phase martensite formed in the rapid cooling stage of step (c) can be softened during the subsequent galvanizing process.
  • it will promote the transformation of part of the austenite into bainite, reducing the ferrite and martensite.
  • the strength difference between austenites is beneficial to improving plasticity; at the same time, the galvanizing process also makes austenite rich in carbon, which ultimately exists in the room temperature structure.
  • this technical solution also takes advantage of the grain refining effect of micro-alloying elements to further improve austenite stability, allowing the steel plate to obtain a sufficient amount of stable austenite under lower alloying element conditions.
  • the inventor further introduces retained austenite into the ferrite and martensite structures of traditional dual-phase steel through reasonable component matching and process design. body, so that the uniform elongation of the high-strength and high-forming cold-rolled hot-dip pure zinc strip steel can be greatly improved under the condition of similar strength, thus broadening the formability of galvanized steel.
  • This high-strength and high-forming cold-rolled hot-dip pure zinc strip has a yield strength of 780 to 1030MPa, a tensile strength of ⁇ 1180MPa, and an elongation of A 50 ⁇ 11%. It has excellent weldability and formability and can be effectively used in the preparation of automobiles. Structural parts, anti-collision parts and other parts have good promotion prospects and application value.
  • the present invention utilizes the TRIP effect of retained austenite to effectively improve the work hardening ability of the steel plate, improve the strong plasticity of the galvanized steel plate, and thereby improve the formability of hot-dip galvanized dual-phase steel. .
  • Figure 1 schematically shows the control process of the hot-dip galvanizing recrystallization annealing process in one embodiment of the manufacturing method of high-strength and high-forming cold-rolled hot-dip pure zinc strip steel according to the present invention.
  • Figure 2 is a photo of the metallographic structure of the high-strength and high-forming cold-rolled hot-dip pure zinc strip of Example 1.
  • the high-strength and high-forming cold-rolled hot-dip pure zinc strips of Examples 1-9 of the present invention are all produced by the following steps:
  • Hot rolling hot-roll the obtained slab, heat the slab at 1200 ⁇ 1280°C, control the holding time to 0.5 ⁇ 5h, control the final rolling temperature to ⁇ 850°C, and coil at the coiling temperature of ⁇ 650°C Coiling hot rolled plate.
  • Cold rolling The hot-rolled plate after pickling is subjected to cold rolling deformation, and the amount of cold rolling deformation is controlled to 30-60%, preferably between 35-50%.
  • the chemical element composition and related process design of the high-strength and high-forming cold-rolled hot-dip pure zinc strip steel in Examples 1 to 9 of the present invention meet the requirements of the design specifications of the present invention.
  • Table 1 lists the mass percentage of each chemical element in the high-strength and high-forming cold-rolled hot-dip pure zinc strip steel of Examples 1-9.
  • Table 2-1 and Table 2-2 list the specific process parameters used in the above manufacturing process steps of the high-strength and high-forming cold-rolled hot-dip pure zinc strip of Example 1-9.
  • a ⁇ is the retained austenite lattice constant (tested by RINT2200/PC rotating target X-ray diffractometer, which uses rotating MoK ⁇ radiation, tube pressure 40kV, tube flow 40mA, step size 0.02°, scanning range 20 30 ⁇ 120°.
  • the measured diffraction spectral lines were fitted by DIFFRAC plus tops 4.0 analysis software for full spectrum fitting.
  • the diffraction data processing software is jade6.5).
  • w C , w Mn , w Al , w Si and w Cu are respectively Mass fractions of carbon, manganese, aluminum, silicon and copper in retained austenite. The relevant observation and analysis results are listed in Table 3 below.
  • Table 3 lists the microstructure observation and analysis results of the substrates of the high-strength and high-forming cold-rolled hot-dip pure zinc strips of Examples 1-9.
  • the matrix of the microstructure of the substrates prepared in Examples 1-9 includes: ferrite, tempered martensite lath, bainite and retained austenite , and its microstructure also includes carbide precipitates with a size less than 80nm, and the specific size of the carbide precipitates is between 30-75nm.
  • the volume phase ratio of retained austenite in the microstructure of the substrates of Examples 1-9 is between 5% and 10%.
  • the inventor further The high-strength and high-formation cold-rolled hot-dip pure zinc strips of the prepared finished products of Examples 1-9 were respectively sampled, and various tests were conducted on the high-strength and high-formation cold-rolled hot-dip pure zinc strip samples of Examples 1-9. Performance test, the relevant test results are listed in Table 4.
  • Tensile test According to GB228.1-2021, use a plate with a gauge length of 50mm to pull the sample to test the yield strength and yield strength of the high-strength and high-forming cold-rolled hot-dip pure zinc strip steel at room temperature in Examples 1-9. Tensile strength and elongation values.
  • Table 3 lists the performance test results of the high-strength and high-forming cold-rolled hot-dip pure zinc strips of Examples 1-9.
  • the high-strength and high-forming cold-rolled hot-dip pure zinc strip steel obtained in Examples 1-9 of the present invention all have excellent mechanical properties, with a yield strength between 790-900MPa and a tensile strength between Between 1185-1250MPa, elongation A 50 between 13-17%.
  • Figure 1 schematically shows the control process of the hot-dip galvanizing recrystallization annealing process in one embodiment of the manufacturing method of high-strength and high-forming cold-rolled hot-dip pure zinc strip steel according to the present invention.
  • the cold-rolled plate when performing the hot-dip galvanizing recrystallization annealing process, the cold-rolled plate is first heated to the soaking temperature T1 at the heating rate V1 and then kept for a period of time t1, and then the soaked steel plate is First, slowly cool to the intermediate temperature T2 at the cooling rate V2, then immediately cool to the galvanizing temperature T3 at the rapid cooling rate V3, and then keep warm for t3. After completing the above steps, the steel plate is heated to T4 at a heating rate V4. After the heat preservation time t4, the steel plate is sent to the zinc pot for galvanizing.
  • the galvanized steel plate can be further cooled to room temperature.
  • Figure 2 is a photo of the metallographic structure of the high-strength and high-forming cold-rolled hot-dip pure zinc strip of Example 1.
  • the microstructure of the high-strength and high-forming cold-rolled hot-dip pure zinc strip steel of Example 1 is ferrite, tempered martensite lath, bainite and retained austenite. austenite, in which the volume phase proportion of retained austenite is 8%.

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Abstract

本发明公开了一种高强度高成形冷轧热镀纯锌带钢，其包括基板和镀覆于基板上的镀锌层，其中所述基板含有Fe和不可避免的杂质元素，所述基板还含有质量百分含量如下的下述各化学元素：C：0.15～0.25％、Mn：2.2～3.0％、Si：0.3～0.9％、Al：0.1～0.5％、Nb：0.01～0.1％、Ti：0.01～0.1％、Cr：0.01～0.3％；所述基板的微观组织的基体包括体积分数为5～15％的残余奥氏体，所述微观组织还包括尺寸小于80nm的碳化物析出相。相应地，本发明还公开了上述的高强度高成形冷轧热镀纯锌带钢的制造方法，其包括步骤：(1)冶炼和铸造；(2)热轧；(3)酸洗；(4)冷轧；(5)热镀锌再结晶退火；(6)镀锌后冷却。

Description

一种高强度高成形冷轧热镀纯锌带钢及其制造方法 技术领域
本发明涉及一种钢材及其制造方法，尤其涉及一种热镀锌钢及其制造方法。
背景技术
近年来，随着汽车工业的迅速发展，汽车白车身用钢也经历了快速迭代，虽然当前所采用的汽车用先进高强钢已经从第一代发展到第三代，但双相钢依然是用量最大的钢种。
与冷轧双相钢相比，镀锌双相钢具有十分优良的耐蚀性，其多用于制备车身结构件和加强件。然而，随着车身结构件设计的越来越复杂，市场和操作人员对钢板的成形性提出了更高的要求，当前所使用的传统热镀锌双相钢已经逐渐难以满足部分车身结构的设计需求。
若采用TRIP钢或TWIP钢，则其延伸率又过于富余，且合金含量较高，会造成相应的浪费及降低可制造性。虽然传统的QP钢和TBF钢能够满足复杂零件的成形性需求且具有较低的合金成本，但过高的Si含量带来制造性和焊接性的降低，限制了其应用。
由此可见，在当前现有技术中，目前1180MPa级别的热镀锌超高强钢的现有专利方案并不多，这在一定程度上也显示了制备该强度级别的热镀锌钢具有较高的技术壁垒。
例如：公开号为CN105506513A，公开日为2016年4月20日，名称为“超高强度冷轧汽车用钢及其制备方法”的中国专利文献，公开了一种超高强冷轧汽车用钢及其生产方法，其典型成分为0.6C-4.5Mn-3Si-5Al，通过控制热轧工艺和连退工艺，使材料获得优异的强塑性，其抗拉强度大于1180MPa的同时，延伸率不低于18％。但大量C、Si、Mn的加入显著提高了制造难度和成本。
又例如：公开号为CN106244923A，公开日为2016年12月21日，名称为“一种磷化性能和成形性能优良的冷轧高强度钢板及其制造方法”的中国专利 文献，公开了一种磷化性能和成形性能优良的冷轧高强度钢板及其制造方法，其典型成分为0.2C-2.5Mn-1.5Si，通过控轧控冷和连续退火处理，可使组织中含有不低于5％的残余奥氏体，其抗拉强度≥1180MPa，延伸率≥14％。在该技术方案中，虽然该钢板的化学元素成分以C、Si、Mn设计为主，但是其仍然具有较高的Si含量，不利于热镀锌产品后续的生产和点焊性能。
再例如：公开号为CN102021482A，公开日为2011年4月20日，名称为“一种冷轧热镀锌双相钢及其制造方法”的中国专利文献，公开了一种1180MPa级冷轧热镀锌双相钢及其制造方法，其典型成分为0.12C-2.0Mn-(0.6～1.4)Si-0.5Cr-0.2Mo，低的合金含量保证了该材料具有良好的制造性和焊接性，其可通过常规DP钢制造工艺，获得1180MPa级别的抗拉强度。但在该技术方案中，由于钢板的微观组织为铁素体+马氏体双相组织，限制了其变形能力，材料的延伸率不高。同时，钢中添加了高含量的Cr元素和Mo元素，其不但增加了合金成本，而且不利于镀锌板表面质量。
因此，为了满足市场和用户的需求，亟须在保证冷轧热镀锌双相钢的可制造性和生产成本的基础上，开发出一种兼具有优良焊接性和成型性的1180MPa级高强度钢。
发明内容
本发明的目的之一在于提供一种高强度高成形冷轧热镀锌钢，该高强度高成形冷轧热镀锌钢通过合理的成分匹配及工艺设计，可以在传统的双相钢所具备的铁素体、马氏体组织中，进一步引入残余奥氏体，以在强度相似情况下，使材料的均匀延伸率大幅提升，拓宽了镀锌钢材的成形性。
该高强度高成形冷轧热镀锌钢的屈服强度为780～1030MPa，抗拉强度≥1180MPa，延伸率A50≥11％，其具有优良焊接性和成型性，可以有效应用于制备汽车结构件、防撞件等零部件，其具有良好的推广前景和应用价值。
为了实现上述目的，本发明提供了一种冷轧热镀锌钢，其包括基板和镀覆于基板上的镀锌层，其中所述基板含有Fe和不可避免的杂质元素，所述基板还含有质量百分含量如下的下述各化学元素：
C：0.15～0.25％、Mn：2.2～3.0％、Si：0.3～0.9％、Al：0.1～0.5％、Nb：0.01～0.1％、Ti：0.01～0.1％、Cr：0.01～0.3％；
所述基板的微观组织的基体包括体积分数为5～15％的残余奥氏体，所述微观组织还包括尺寸小于80nm的碳化物析出相。本文中，碳化物析出相的尺寸是指其粒径。
在一些实施方案中，所述基板的微观组织的基体中残余奥氏体的体积分数为5％、6％、7％、8％、9％、10％、11％、12％、13％、14％、15％或上述任意两个值的范围内。
在一些实施方案中，碳化物析出相的粒径为10nm、20nm、30nm、40nm、50nm、60nm、70nm、80nm或上述任意两个值的范围内，如30～70nm。
在一些实施方案中，所述基板的微观组织的基体包括铁素体、回火马氏体板条、贝氏体和残余奥氏体。
进一步地，在本发明所述的高强度高成形冷轧热镀纯锌带钢中，所述基板的各化学元素质量百分比为：
C：0.15～0.25％、Mn：2.2～3.0％、Si：0.3～0.9％、Al：0.1～0.5％、Nb：0.01～0.1％、Ti：0.01～0.1％、Cr：0.01～0.3％；余量为Fe和不可避免杂质。
本发明的冷轧热镀锌钢具有高强度和高成形性，表现在屈服强度为780～1030MPa，抗拉强度≥1180MPa，延伸率A50≥11％。
在当前现有技术中，传统热镀锌钢为了满足镀锌线的冷却速度，往往需要通过添加足量的Cr、Mo等合金元素来提高基板的淬透性，其会造成成本增加；同时，这种传统的热镀锌钢的低碳设计也不利于奥氏体温度存在于室温，故而其组织多为铁素体和马氏体。
在本发明中，发明人对化学成分进行了全新的设计，其通过适当增加碳含量，并结合多合金元素的匹配，可以有效提高钢材奥氏体的稳定性，同时降低Cr、Mo等合金元素的使用量，其不仅能够有效降低成本，还可改善增碳对钢材焊接性能的恶化，同时保证了一定的可制造性。
在本发明所述的高强度高成形冷轧热镀纯锌带钢中，各化学元素的设计原理如下所述：
C：在本发明所述的高强度高成形冷轧热镀纯锌带钢中，C是热镀锌钢中重要的组成元素，其直接影响了镀锌板的强塑性。当钢中C元素含量过低时，其在临界区退火时所形成的奥氏体含量会减少，且奥氏体稳定性和马氏体淬硬性会下降，难于保证强塑性；同时，钢中C元素含量也不宜过高，当钢中C元 素含量过高时，则会导致钢材的塑性和焊接性下降。因此，考虑到C元素含量对钢材性能的影响，在本发明所述的高强度高成形冷轧热镀纯锌带钢中，将C元素的质量百分含量控制在0.15～0.25％之间。
Mn：在本发明所述的高强度高成形冷轧热镀纯锌带钢中，Mn元素可以提高奥氏体稳定性，使C曲线右移，从而降低马氏体临界冷却速率。钢中Mn元素含量不宜过低，Mn含量过低时，会使钢材的淬透性降低，强化作用减弱；同时，钢中也不宜添加过量的Mn，当钢中Mn元素含量过高时，会影响基板焊接性和表面镀锌质量。基于此，为了发挥Mn元素的有益效果，在本发明所述的高强度高成形冷轧热镀纯锌带钢中，将Mn元素的质量百分含量控制在2.2～3.0％之间，例如2.4％、2.6％、2.8％。
Si：在本发明所述的高强度高成形冷轧热镀纯锌带钢中，Si是铁素体固溶强化元素，其可以强烈提高钢板强度。同时，Si元素还可以促使C原子从铁素体向奥氏体富集，净化铁素体，提高奥氏体稳定性。但需要注意的是，钢中Si元素含量也不宜过高，太高含量的Si元素会直接影响基板的可镀性和点焊性能。因此，为了发挥Si元素的有益效果，必须严格控制钢中Si元素含量，在本发明所述的高强度高成形冷轧热镀纯锌带钢中，将Si元素的质量百分含量控制在0.3～0.9％之间，例如0.4％、0.5％、0.6％、0.7％、0.8％。
Al：在本发明所述的高强度高成形冷轧热镀纯锌带钢中，Al元素的作用与Si元素相似，其可以有效抑制碳化物析出，并促进碳元素向奥氏体扩散；并且Al元素还可以提高奥氏体的层错能，提高奥氏体稳定性。同时，钢中添加的Al还可以通过形成AlN钉扎晶界，细化晶粒。
但需要注意的是，钢中Al元素的含量同也不宜过高，当钢液中Al元素含量过高时，容易产生连铸过程水口堵塞、显著提高Ac3等问题。因此，为了发挥Al元素的有益效果，在本发明所述的高强度高成形冷轧热镀纯锌带钢中，将Al元素的质量百分含量控制在0.1～0.5％之间，例如0.2％、0.3％、0.4％。
Ti：在本发明所述的高强度高成形冷轧热镀纯锌带钢中，Ti与C、N结合会形成Ti(C，N)、TiN和TiC，其能够细化铸态组织，并可以在热加工时阻碍晶粒粗化。但需要注意的是，钢中Ti元素含量不宜过高，添加过量Ti会使成本增加，并会导致上述析出物含量和尺寸增加，进而降低钢板的延展性。因此，为了发挥Ti元素的有益作用，在本发明所述的高强度高成形冷轧热镀锌钢中， 需要将Ti元素的质量百分含量控制在0.01～0.1％之间，例如0.02％、0.04％、0.06％、0.08％。在一些实施方案中，将Ti元素的质量百分含量控制在0.01～0.08％之间。
Nb：在本发明所述的高强度高成形冷轧热镀纯锌带钢中，Nb元素会强烈抑制动态再结晶，其通过与C、N结合形成Nb(C，N)，可以有效地抑制热加工过程中晶粒粗化，细化铁素体晶粒。Nb和Ti的加入会显著细化基体的奥氏体组织，细小的奥氏体晶粒尺寸更加稳定，具有优良的热稳定性和机械稳定性。但需要注意的是，钢中Nb元素含量同样不宜过高，添加过量的Nb会恶化钢的热加工性能和钢板的韧性。基于此，为了发挥Nb元素的有益效果，在本发明中，将Nb元素的质量百分含量控制在0.01～0.1％之间，例如0.02％、0.04％、0.06％、0.08％。在一些实施方案中，将Nb元素的质量百分含量控制在0.01～0.07％之间。
Cr：在本发明所述的高强度高成形冷轧热镀纯锌带钢中，Cr可以有效细化晶粒组织并抑制热加工时晶粒粗化，且Cr是铁素体形成元素，其可以促进C向奥氏体扩散，提高奥氏体稳定性，降低退火时临界冷却速度。但钢中Cr元素含量同样不宜过高，过高Cr含量会破坏钢的延展性和表面可镀性。为此，必须严格控制钢中Cr元素的含量，在本发明中，将Cr元素的质量百分含量控制在0.01～0.3％之间，例如0.02％、0.05％、0.1％、0.15％、0.2％、0.25％。
进一步地，在本发明所述的高强度高成形冷轧热镀纯锌带钢中，所述基板的化学元素还包括下述各项的至少一种：Mo：0.02～0.2％，V：0.005～0.2％，Cu：0.003～0.5％，B：0.0005～0.003％。
为了进一步优化本发明所述的高强度高成形冷轧热镀纯锌带钢的性能，在一些优选的实施方式中，钢中还可以进一步添加Mo、V、Cu、B元素。
Mo：在本发明中，Mo元素的作用与Cr相似，其能够使珠光体和贝氏体C曲线右移，并有效提高钢材的淬透性；同时，Mo元素还可通过固溶强化和析出强化显著提高强度，且不会影响表面镀锌质量。但Mo元素的价格昂贵，考虑到生产成本，不宜过量添加，因此，在本发明所述的高强度高成形冷轧热镀纯锌带钢中，将Mo元素的质量百分含量控制在0.02～0.2％之间，例如0.05％、0.1％、0.15％。
V：在本发明中，V在热镀锌钢中主要以VC形式存在，通过其钉扎晶界 细化晶粒和铁素体中弥散析出强化，来提高钢的强度和韧性。同时，晶粒的细化提高了奥氏体的热稳定性和机械稳定性，有利于强塑性的提高。但添加V元素也会进一步增加钢材的合金成本，因此，在本发明所述的高强度高成形冷轧热镀纯锌带钢中，将V元素的质量百分含量控制在0.005～0.2％之间，例如0.01％、0.03％、0.05％、0.1％、0.15％。
Cu：在本发明中，Cu是奥氏体稳定化元素，其可以阻碍高温下晶粒粗化，有利于组织中获得一定量的奥氏体；同时，在镀锌过程中，Cu元素会以ε-Cu析出，从而有效提高钢材的强度。但钢中Cu元素含量也不宜过高，Cu含量过高时会对热变形加工产生不利影响，因此，在本发明所述的高强度高成形冷轧热镀纯锌带钢中，将Cu元素的质量百分含量控制在0.003～0.5％之间，例如0.005％、0.01％、0.05％、0.1％、0.2％、0.4％。
B：在本发明中，B元素可以阻碍热轧过程中钢材的再结晶，有利于由累积变形量所引起的微观组织结构细化。但钢中B元素含量也不宜过高，添加过量的B会生成BC从而降低钢的延展性，因此，在本发明所述的高强度高成形冷轧热镀纯锌带钢中，将B元素的质量百分含量控制在0.0005～0.003％之间，例如0.001％、0.0015％、0.002％、0.0025％。
进一步地，在本发明所述的高强度高成形冷轧热镀纯锌带钢中，所述基板中的各化学元素质量百分含量满足：Si+Al+Cr≤1.2％。
在本发明上述技术方案中，本发明在控制单一化学元素质量百分含量的同时，还可以进一步控制钢中的元素配比，并使得Si、Al和Cr的质量百分含量满足：Si+Al+Cr≤1.2％。通过控制Si+Al+Cr≤1.2％，不仅可以确保钢板获得较好的可制造性，同时还能够促进马氏体中碳向奥氏体中的配分，有利于提高钢板的塑性。
在一些实施方案中，Si、Al、Cr的质量百分含量满足：Si+Al+Cr为0.4％、0.5％、0.6％、0.7％、0.8％、0.9％、1.0％、1.1％、1.2％或上述任意两个值的范围内。在一些实施方案中，Si、Al、Cr的质量百分含量满足：0.6％≤Si+Al+Cr≤1.2％
进一步地，在本发明所述的高强度高成形冷轧热镀纯锌带钢中，在基板的不可避免的杂质中P、S、N的质量百分含量满足：P≤0.02％、S≤0.01％、N≤0.008％。
在本发明所述的高强度高成形冷轧热镀纯锌带钢中，P、S、N元素均为钢管中的杂质元素，在技术条件允许情况下，为了获得性能更好且质量更优的管材，应尽可能降低高强度高成形冷轧热镀纯锌带钢中杂质元素的含量。
因此，在本发明中，必须严格地控制钢中P、S、N元素的含量，并控制为P≤0.02％、S≤0.01％、N≤0.008％，钢质越纯净效果更佳。
进一步地，在本发明所述的高强度高成形冷轧热镀纯锌带钢中，所述基板中的各化学元素质量百分含量满足：3C+Si+6P+8S≤2.0％。
相应地，本发明在控制单一化学元素质量百分含量的同时，还可以进一步控制钢中的C、Si元素与杂质元素P、S的含量满足：3C+Si+6P+8S≤2.0％。
在本发明中，通过控制3C+Si+6P+8S≤2.0％，可以确保所制备的高强度高成形冷轧热镀纯锌带钢获得良好的焊接性能。
在一些实施方案中，C、Si、P、S的质量百分含量满足：3C+Si+6P+8S为0.75％、0.8％、1.0％、1.2％、1.4％、1.6％、1.8％、2.0％或上述任意两个值的范围内。在一些实施方案中，C、Si、P、S的质量百分含量满足：0.8％≤3C+Si+6P+8S≤2.0％
进一步地，在本发明所述的高强度高成形冷轧热镀纯锌带钢中，所述基板的微观组织的基体还包括铁素体、回火马氏体板条和贝氏体。
进一步地，在本发明所述的高强度高成形冷轧热镀纯锌带钢中，所述残余奥氏体中C的质量百分含量≥0.8％。
在一些实施方案中，在本发明所述的冷轧热镀锌钢中，所述残余奥氏体中C的质量百分含量为0.8％、0.9％、1.0％、1.1％、1.2％、1.3％、1.4％、1.5％或上述任意两个值的范围内。在一些实施方案中，在本发明所述的冷轧热镀锌钢中，所述残余奥氏体中C的质量百分含量为0.8～1.5％。
进一步地，在本发明所述的高强度高成形冷轧热镀纯锌带钢中，所述回火马氏体板条中分布有ε-碳化物。
进一步地，在本发明所述的高强度高成形冷轧热镀纯锌带钢中，所述碳化物析出相与基体呈共格或半共格状态。
进一步地，在本发明所述的高强度高成形冷轧热镀纯锌带钢中，基板单面的所述镀锌层的厚度为5～200μm，例如15～185μm。
在本发明上述技术方案中，利用镀锌工艺，可以在本发明所述的高强度高 成形冷轧热镀纯锌带钢的基板的每一侧热镀生成厚度为5～200μm的镀层，热镀结束后将钢板冷却至室温。
进一步地，在本发明所述的高强度高成形冷轧热镀纯锌带钢中，其屈服强度为780～1030MPa，抗拉强度≥1180MPa，延伸率A50≥11％。
进一步地，在本发明所述的高强度高成形冷轧热镀纯锌带钢中，其屈服强度为800～1030MPa，或为830～1030MPa，或为780～950MPa。
进一步地，在本发明所述的高强度高成形冷轧热镀纯锌带钢中，其抗拉强度≥1200MPa，或为1180～1250MPa。
相应地，本发明的另一目的在于提供上述的高强度高成形冷轧热镀纯锌带钢的制造方法，该制造方法对退火工艺进行了优化设计，其可以有效制备本发明上述的高强度高成形冷轧热镀纯锌带钢，以确保钢材获得优异的力学性能。
为了实现上述目的，本发明提出了上述的高强度高成形冷轧热镀纯锌带钢的制造方法，其包括步骤：
(1)冶炼和铸造；
(2)热轧；
(3)酸洗；
(4)冷轧；
(5)热镀锌再结晶退火：
(a)将钢板以1～20℃/s的加热速率V1加热至均热温度T1＝780～850℃，保温30～240s；
(b)将均热后的钢板以2～20℃/s的冷却速率V2冷却至中间温度T2，T2＝640～850℃；
(c)将钢板以20～80℃/s的冷却速率V3冷却至淬火温度T3保温10～200s，其中T3＝Mf+20～Ms-30，Ms、Mf分别为中间温度T2时组织中的奥氏体在冷速V3下向马氏体转变的开始温度和终止温度，且V3＞V2；
(d)将钢板以10～50℃/s的升温速率V4加热至T4，T4＝420～500℃，保温5～200s；
(e)钢板进入锌锅镀锌；
(6)镀锌后冷却。
在本发明中，本发明所述的高强度高成形冷轧热镀纯锌带钢的制备需要依 次经历冶炼及连铸、热轧、酸洗、冷轧、热镀锌再结晶退火工艺和镀锌后冷却的流程。
在本发明上述制造方法中，发明人优化了步骤(5)的热镀锌再结晶退火过程，热镀锌再结晶退火过程的工艺参数与钢种成分设计密切相关，它决定镀锌板内部软相铁素体和硬相马氏体的相对含量，尤其是残余奥氏体的尺寸和形貌。
在本发明中，发明人采用淬火配分退火工艺处理冷轧钢板，其热镀锌再结晶退火的工艺步骤如上述步骤(a)-(e)所示。
在步骤(a)中，需要将冷轧板以加热速率V1加热至均热温度T1后保温t1时间段。其中，具体选取V1＝1～20℃/s；T1＝780～850℃；t1＝30～240s。在一些实施方案中，V1＝3～18℃/s。
在该工艺步骤中，如果均热温度T1低于780℃和均热保温时间t1短于30s，则对应于本发明中的设计成分的基板的基体组织并不能够获得足量的奥氏体或钢板基体碳化物尚未完全溶解以形成奥氏体颗粒。相应地，当均热温度T1高于850℃和均热保温时间t1长于240s时，则均热处理后钢板中奥氏体含量会显著增加、奥氏体C含量显著降低，且形成的奥氏体和铁素体晶粒粗化。上述因素均会使钢中的奥氏体稳定性降低，从而导致Ms点过高，进而引起镀锌钢板的内部残余奥氏体稳定性降低，使后续的淬火温度过高。
在步骤(b)、(c)和(d)中，需要将均热处理后的钢板先以冷却速率V2缓冷冷却至中间温度T2后，立即以冷却速率V3冷却至淬火温度T3，而后保温t3时间，后再将钢板以升温速率V4加热至T4，并保温t4时间。
其中，T3＝Mf+20～Ms-30，Ms、Mf分别为中间温度T2时组织中的奥氏体在冷速V3下向马氏体转变的开始温度和终止温度，且V3＞V2。
在该技术方案中，缓冷速率V2和中间温度T2的选取主要是考虑：避免均热处理形成的奥氏体在步骤(b)的缓冷段分解，以便于操作，使退火热处理顺利从步骤(a)的均热段过渡到步骤(c)的快冷段，并维持冷轧钢板的板形。因此，针对本发明所选取的化学成分，选取V2＝2～20℃/s；T2＝640～850℃(如640～820℃)。当然，若选取的中间温度T2＝T1时，则表明在步骤(a)的均热处理后无需进行后续步骤(b)的缓冷处理。
相应地，针对本发明所选取的化学成分，发明人还进一步选取步骤(c)快冷段的冷却速率V3＝20～80℃/s，并且V3＞V2。其中，快冷速率V3的选取需 要尽可能地减少冷却过程中钢板基体中的奥氏体分解，以确保在淬火温度T3形成足量的马氏体和贝氏体。当设计的T3温度过高，则马氏体含量不足，钢材的强度很难保证；若T3温度过低，则形成马氏体过多，残留奥氏体含量不足，对延伸率有不利影响。另外，在T3温度保温阶段也有可能促进贝氏体的形成，有利于碳元素的进一步富集，改善力学性能。
在本发明中，完成步骤(c)快冷段工艺后，需要进一步在步骤(d)中以升温速率V4加热至T4，并保温t4时间。该T4温度可使马氏体中的C向相邻奥氏体中富集，提高奥氏体稳定性，同时可伴随弥散强化相的析出而进一步强化基体。但停留时间过长会引起马氏体回火、奥氏体分解及析出相粗化从而恶化镀锌板的强塑性。
综上，从实效性和经济性上考虑，为获取适量且具有良好稳定性的残余奥氏体，在上述步骤中，控制T3＝Mf+20～Ms-30，并控制T3温度的保温时间t3＝10～200s(如30～180s)，控制T4＝420～500℃，并控制保温时间t4＝5～200s(如15～180s)。
当然，在一些优选的实施方式中，为了获得更优的实施效果，可以进一步优选地控制T3＝220～350℃，控制保温时间t3＝10～120s。
进一步地，在本发明所述的制造方法中，在所述步骤(2)中，采用1200～1280℃加热板坯，保温时间为0.5～5h，控制终轧温度≥850℃(如850～940℃或880～940℃)，卷取温度≤650℃(如520～650℃或520～630℃)。
进一步地，在本发明所述的制造方法中，在所述步骤(4)中，控制冷轧变形量为30～60％，优选地可以控制在35～50％之间。
进一步地，在本发明所述的制造方法中，在所述步骤(5)中，锌锅温度为450～500℃。
进一步地，在本发明所述的制造方法中，在所述步骤(6)中，将镀锌钢板以≥20℃/s(如20～40℃/s或30～40℃/s)的冷却速率冷却至室温。
相较于现有技术，本发明所述的高强度高成形冷轧热镀纯锌带钢及其制造方法具有如下所述的优点以及有益效果：
(1)本发明所述的高强度高成形冷轧热镀纯锌带钢采用了合理的化学成分，其在化学成分设计时，适当地提高了C元素的含量，并降低了Cr、Mo等合金元素的含量，其不仅可以大大降低合金成本，还有效改善了钢材的可制造 性，该高强度高成形冷轧热镀纯锌带钢可在现有高强钢连续退火产线进行生产，且无需做较大调整，具有较好的推广应用前景。
(2)本发明所述的高强度高成形冷轧热镀纯锌带钢采用了合理的化学成分，通过对合金元素配比的设计，使镀锌钢板获得了良好的焊接性能。本发明通过低合金含量，特别是对C、Si、P、S的应用限制，保证了该镀锌钢板具有良好的点焊性能。
(3)本发明对制备工艺进行了优化设计，其优化设计了一种新的热镀锌再结晶退火工艺，并具体控制了其各阶段参数。利用该退火工艺，在步骤(c)快冷阶段所形成的硬相马氏体能够在随后镀锌过程中软化，同时会促进部分奥氏体转变为贝氏体，降低了铁素体和马氏体之间强度差，有益于塑性提高；同时镀锌过程也使奥氏体富碳，最终存在于室温组织。此外，该技术方案还利用了微合金元素细化晶粒的作用，以进一步提高奥氏体稳定性，使钢板得以在较低合金元素条件下，获得足量的稳定奥氏体。
综上所述可以看出，在本发明中，发明人通过合理的成分匹配及工艺设计，在传统的双相钢所具备的铁素体、马氏体组织中，进一步地引入了残余奥氏体，以在强度相似情况下，使该高强度高成形冷轧热镀纯锌带钢的均匀延伸率大幅提升，从而拓宽了镀锌钢材的成形性。
该高强度高成形冷轧热镀纯锌带钢的屈服强度为780～1030MPa，抗拉强度≥1180MPa，延伸率A50≥11％，其具有优良焊接性和成型性，可以有效应用于制备汽车结构件、防撞件等零部件，其具有良好的推广前景和应用价值。
在实际应用过程中，在钢板变形时，本发明利用残余奥氏体的TRIP效应，可以有效提高钢板的加工硬化能力，提高镀锌钢板的强塑性，进而改善热镀锌双相钢的成形性。
附图说明
图1示意性地显示了本发明所述的高强度高成形冷轧热镀纯锌带钢的制造方法在一种实施方式下进行热镀锌再结晶退火工艺时的控制过程示意图。
图2为实施例1的高强度高成形冷轧热镀纯锌带钢的金相组织照片。
具体实施方式
下面将结合说明书附图和具体的实施例对本发明所述的高强度高成形冷轧热镀纯锌带钢及其制造方法做进一步的解释和说明，然而该解释和说明并不对本发明的技术方案构成不当限定。
实施例1-9
本发明所述实施例1-9的高强度高成形冷轧热镀纯锌带钢均采用以下步骤制得：
(1)按照表1所示的化学元素的质量百分配比进行冶炼和铸造。
(2)热轧：对获得的板坯进行热轧，采用1200～1280℃加热板坯，并控制保温时间为0.5～5h，控制终轧温度≥850℃，并在卷取温度≤650℃下卷取热轧板。
(3)酸洗：对热轧后的热轧板进行酸洗。
(4)冷轧：对酸洗后的热轧板进行冷轧变形，并控制冷轧变形量为30～60％，优选地可以控制在35～50％之间。
(5)热镀锌再结晶退火：
(a)将钢板以1～20℃/s的加热速率V1加热至均热温度T1＝780～850℃，保温30～240s；
(b)将均热后的钢板以2～20℃/s的冷却速率V2冷却至中间温度T2，T2＝640～850℃；
(c)将钢板以20～80℃/s的冷却速率V3冷却至淬火温度T3保温10～200s，其中T3＝Mf+20～Ms-30，Ms、Mf分别为中间温度T2时组织中的奥氏体在该冷速下向马氏体转变的开始温度和终止温度，且V3＞V2；
(d)将钢板以10～50℃/s的升温速率V4加热至T4，T4＝420～500℃，保温5～200s；
(e)钢板进入锌锅镀锌。
(6)镀锌后冷却，镀锌结束后，将钢板以不小于20℃/s的冷却速率缓冷至室温。
在本发明中，本发明所述实施例1-9的高强度高成形冷轧热镀纯锌带钢的化学元素成分和相关工艺设计均满足本发明设计规范要求。
表1列出了实施例1-9的高强度高成形冷轧热镀纯锌带钢中各化学元素质量百分比。
表1.(wt％，余量为Fe和除P、S、N外其他的不可避免的杂质)
表2-1和表2-2列出了实施例1-9的高强度高成形冷轧热镀纯锌带钢在上述制造工艺步骤中所采用的具体工艺参数。
表2-1.
表2-2.

需要说明的是，在上述制造工艺中，在所制备的基板进行镀锌之前，为了分析基板的微观组织，发明人将制备的各实施例的基板的分别取样，并对实施例1-9的所制备的基板样品的微观组织进行了观察和分析。本文中，微观组织用ZEISS Axio Imager M2m型光学显微镜来观察。另外，纳米析出物和微观组织的细节进一步通过球差矫正场发射透射电镜(TEM；型号JEOL ARM-200F)来观测分析，TEM工作加速电压为200kV。残余奥氏体中C质量百分含量采用以下公式检测：
aγ＝3.578+0.033wC+0.0056wAl+0.00095wMn+0.00157wSi+0.0015wCu
其中，aγ为残余奥氏体点阵常数(由RINT2200/PC型转靶X射线衍射仪进行测试，该仪器采用旋转MoKα辐射，管压40kV，管流40mA，步长0.02°，扫描20范围30～120°。测得的衍射谱线经DIFFRAC plus tops 4.0分析软件进行全谱拟合，衍射数据处理软件为jade6.5)，wC、wMn、wAl、wSi和wCu分别是残余奥氏体中碳、锰、铝、硅和铜的质量分数。相关观察分析结果列于下述表3之中。
表3列出了针对实施例1-9的高强度高成形冷轧热镀纯锌带钢的基板的微观组织观察分析结果。
表3.

如上述表3所示，在本发明中，所制备的实施例1-9的基板的微观组织的基体均包括：铁素体、回火马氏体板条、贝氏体和残余奥氏体，且其微观组织还包括尺寸小于80nm的碳化物析出相，其碳化物析出相具体尺寸在30-75nm之间。此外，实施例1-9的基板微观组织中的残余奥氏体的体积相比例在5～10％之间。
观察发现，在本发明所制备的实施例1-9的基板中，其微观组织中的回火马氏体板条中分布有ε-碳化物，其残余奥氏体中C含量不低于0.8％，且碳化物析出相与基体成共格或半共格状态。
相应地，在完成上述针对微观组织的观察和分析后，为了进一步说明本发明所制备的实施例1-9的高强度高成形冷轧热镀纯锌带钢具有优异的性能，发明人进一步将制备的成品实施例1-9的高强度高成形冷轧热镀纯锌带钢的分别取样，并对实施例1-9的高强度高成形冷轧热镀纯锌带钢样品进行了各项性能测试，相关测试结果列于表4中。
相关性能检测手段如下所述：
拉伸试验：按照GB228.1-2021，使用标距为50mm的板拉试样，以测试获得实施例1-9的高强度高成形冷轧热镀纯锌带钢在室温下的屈服强度、抗拉强度和延伸率数值。
表3列出了实施例1-9的高强度高成形冷轧热镀纯锌带钢的性能测试结果。
表3.

参阅表3可知，本发明所获得的实施例1-9的高强度高成形冷轧热镀纯锌带钢均具有优异的力学性能，其屈服强度在790-900MPa之间，其抗拉强度在1185-1250MPa之间，延伸率A50在13-17％之间。
图1示意性地显示了本发明所述的高强度高成形冷轧热镀纯锌带钢的制造方法在一种实施方式下进行热镀锌再结晶退火工艺时的控制过程示意图。
如图1所示，在本发明中，在进行热镀锌再结晶退火工艺时，先将冷轧板以加热速率V1加热至均热温度T1后保温t1时间段，而后将均热处理后的钢板先以V2冷速缓冷至中间温度T2后立即以快冷速率V3冷却至镀锌温度T3后保温t3时间。完成上述步骤后，再将钢板以升温速率V4加热至T4，保温t4时间后，将钢板送入锌锅镀锌中进行镀锌。
相应地，在完成上述热镀锌再结晶退火工艺后，镀锌完成的钢板可以进一步冷却至室温。
图2为实施例1的高强度高成形冷轧热镀纯锌带钢的金相组织照片。
如图2所示，在该实施例中，实施例1的高强度高成形冷轧热镀纯锌带钢的微观组织为铁素体、回火马氏体板条、贝氏体和残余奥氏体，其中残余奥氏体的体积相比例为8％。
需要说明的是，本案中各技术特征的组合方式并不限本案权利要求中所记载的组合方式或是具体实施例所记载的组合方式，本案记载的所有技术特征可以以任何方式进行自由组合或结合，除非相互之间产生矛盾。
还需要注意的是，以上所列举的实施例仅为本发明的具体实施例。显然本发明不局限于以上实施例，随之做出的类似变化或变形是本领域技术人员能从本发明公开的内容直接得出或者很容易便联想到的，均应属于本发明的保护范围。

Claims (15)

  1. 一种高强度高成形冷轧热镀纯锌带钢，其包括基板和镀覆于基板上的镀锌层，其中所述基板含有Fe和不可避免的杂质元素，其特征在于，所述基板还含有质量百分含量如下的下述各化学元素：
    C：0.15～0.25％、Mn：2.2～3.0％、Si：0.3～0.9％、Al：0.1～0.5％、Nb：0.01～0.1％、Ti：0.01～0.1％、Cr：0.01～0.3％；
    所述基板的微观组织的基体包括体积分数为5～15％的残余奥氏体，所述微观组织还包括尺寸小于80nm的碳化物析出相。
  2. 如权利要求1所述的高强度高成形冷轧热镀纯锌带钢，其特征在于，所述基板的各化学元素质量百分比为：
    C：0.15～0.25％、Mn：2.2～3.0％、Si：0.3～0.9％、Al：0.1～0.5％、Nb：0.01～0.1％、Ti：0.01～0.1％、Cr：0.01～0.3％；余量为Fe和不可避免杂质。
  3. 如权利要求1或2所述的高强度高成形冷轧热镀纯锌带钢，其特征在于，所述基板的化学元素还包括下述各项的至少一种：Mo：0.02～0.2％，V：0.005～0.2％，Cu：0.003～0.5％，B：0.0005～0.003％。
  4. 如权利要求1或2所述的高强度高成形冷轧热镀纯锌带钢，其特征在于，所述基板中的各化学元素质量百分含量满足：Si+Al+Cr≤1.2％。
  5. 如权利要求1或2所述的高强度高成形冷轧热镀纯锌带钢，其特征在于，在基板的不可避免的杂质中P、S、N的质量百分含量满足：P≤0.02％、S≤0.01％、N≤0.008％。
  6. 如权利要求1或2所述的高强度高成形冷轧热镀纯锌带钢，其特征在于，所述基板中的各化学元素质量百分含量满足：3C+Si+6P+8S≤2.0％。
  7. 如权利要求1或2所述的高强度高成形冷轧热镀纯锌带钢，其特征在于，所述基板的微观组织的基体还包括铁素体、回火马氏体板条和贝氏体。
  8. 如权利要求1或2所述的高强度高成形冷轧热镀纯锌带钢，其特征在于，所述残余奥氏体中C的质量百分含量不低于0.8％。
  9. 如权利要求7所述的高强度高成形冷轧热镀纯锌带钢，其特征在于，所述回火马氏体板条中分布有ε-碳化物。
  10. 如权利要求1或2所述的高强度高成形冷轧热镀纯锌带钢，其特征在于，所述 碳化物析出相与基体呈共格或半共格状态。
  11. 如权利要求1或2所述的高强度高成形冷轧热镀纯锌带钢，其特征在于，基板单面的所述镀锌层的厚度为5～200μm。
  12. 如权利要求1或2所述的高强度高成形冷轧热镀纯锌带钢，其特征在于，其屈服强度为780～1030MPa，抗拉强度≥1180MPa，延伸率A50≥11％。
  13. 如权利要求1-12中任意一项所述的高强度高成形冷轧热镀纯锌带钢的制造方法，其特征在于，包括步骤：
    (1)冶炼和铸造；
    (2)热轧；
    (3)酸洗；
    (4)冷轧；
    (5)热镀锌再结晶退火：
    (a)将钢板以1～20℃/s的加热速率V1加热至均热温度T1＝780～850℃，保温30～240s；
    (b)将均热后的钢板以2～20℃/s的冷却速率V2冷却至中间温度T2，T2＝640～850℃；
    (c)将钢板以20～80℃/s的冷却速率V3冷却至淬火温度T3保温10～200s，其中T3＝Mf+20～Ms-30，Ms、Mf分别为中间温度T2时组织中的奥氏体在冷速V3下向马氏体转变的开始温度和终止温度，且V3＞V2；
    (d)将钢板以10～50℃/s的升温速率V4加热至T4，T4＝420～500℃，保温5～200s；
    (e)钢板进入锌锅镀锌；
    (6)镀锌后冷却。
  14. 如权利要求13所述的制造方法，其特征在于，在所述步骤(2)中，采用1200～1280℃加热板坯，保温时间为0.5～5h，控制终轧温度≥850℃，卷取温度≤650℃；和/或，在所述步骤(4)中，控制冷轧变形量为30～60％。
  15. 如权利要求13所述的制造方法，其特征在于，在所述步骤(5)中，锌锅温度为450～500℃；和/或，在所述步骤(6)中，将镀锌钢板以≥20℃/s的冷却速率冷却至室温。
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CN113416887A (zh) * 2021-05-21 2021-09-21 鞍钢股份有限公司 汽车超高成形性980MPa级镀锌钢板及制备方法
CN113416889A (zh) * 2021-05-21 2021-09-21 鞍钢股份有限公司 焊接性能良好超高强热镀锌dh1470钢及制备方法

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