WO2023155868A1 - 抗点焊lme裂纹的高强钢复合镀锌板及其制备方法 - Google Patents

抗点焊lme裂纹的高强钢复合镀锌板及其制备方法 Download PDF

Info

Publication number
WO2023155868A1
WO2023155868A1 PCT/CN2023/076709 CN2023076709W WO2023155868A1 WO 2023155868 A1 WO2023155868 A1 WO 2023155868A1 CN 2023076709 W CN2023076709 W CN 2023076709W WO 2023155868 A1 WO2023155868 A1 WO 2023155868A1
Authority
WO
WIPO (PCT)
Prior art keywords
strength steel
low
strength
steel composite
steel
Prior art date
Application number
PCT/CN2023/076709
Other languages
English (en)
French (fr)
Inventor
雷鸣
潘华
王利
薛鹏
孙中渠
吴天海
刘成杰
吴岳
温中令
Original Assignee
宝山钢铁股份有限公司
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Application filed by 宝山钢铁股份有限公司 filed Critical 宝山钢铁股份有限公司
Publication of WO2023155868A1 publication Critical patent/WO2023155868A1/zh

Links

Classifications

    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B21—MECHANICAL METAL-WORKING WITHOUT ESSENTIALLY REMOVING MATERIAL; PUNCHING METAL
    • B21B—ROLLING OF METAL
    • B21B1/00—Metal-rolling methods or mills for making semi-finished products of solid or profiled cross-section; Sequence of operations in milling trains; Layout of rolling-mill plant, e.g. grouping of stands; Succession of passes or of sectional pass alternations
    • B21B1/38—Metal-rolling methods or mills for making semi-finished products of solid or profiled cross-section; Sequence of operations in milling trains; Layout of rolling-mill plant, e.g. grouping of stands; Succession of passes or of sectional pass alternations for rolling sheets of limited length, e.g. folded sheets, superimposed sheets, pack rolling
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B23—MACHINE TOOLS; METAL-WORKING NOT OTHERWISE PROVIDED FOR
    • B23K—SOLDERING OR UNSOLDERING; WELDING; CLADDING OR PLATING BY SOLDERING OR WELDING; CUTTING BY APPLYING HEAT LOCALLY, e.g. FLAME CUTTING; WORKING BY LASER BEAM
    • B23K11/00—Resistance welding; Severing by resistance heating
    • B23K11/10—Spot welding; Stitch welding
    • B23K11/11—Spot welding
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B23—MACHINE TOOLS; METAL-WORKING NOT OTHERWISE PROVIDED FOR
    • B23P—METAL-WORKING NOT OTHERWISE PROVIDED FOR; COMBINED OPERATIONS; UNIVERSAL MACHINE TOOLS
    • B23P15/00—Making specific metal objects by operations not covered by a single other subclass or a group in this subclass
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B32—LAYERED PRODUCTS
    • B32B—LAYERED PRODUCTS, i.e. PRODUCTS BUILT-UP OF STRATA OF FLAT OR NON-FLAT, e.g. CELLULAR OR HONEYCOMB, FORM
    • B32B15/00—Layered products comprising a layer of metal
    • B32B15/01—Layered products comprising a layer of metal all layers being exclusively metallic
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B32—LAYERED PRODUCTS
    • B32B—LAYERED PRODUCTS, i.e. PRODUCTS BUILT-UP OF STRATA OF FLAT OR NON-FLAT, e.g. CELLULAR OR HONEYCOMB, FORM
    • B32B15/00—Layered products comprising a layer of metal
    • B32B15/01—Layered products comprising a layer of metal all layers being exclusively metallic
    • B32B15/011—Layered products comprising a layer of metal all layers being exclusively metallic all layers being formed of iron alloys or steels
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B32—LAYERED PRODUCTS
    • B32B—LAYERED PRODUCTS, i.e. PRODUCTS BUILT-UP OF STRATA OF FLAT OR NON-FLAT, e.g. CELLULAR OR HONEYCOMB, FORM
    • B32B15/00—Layered products comprising a layer of metal
    • B32B15/18—Layered products comprising a layer of metal comprising iron or steel
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B32—LAYERED PRODUCTS
    • B32B—LAYERED PRODUCTS, i.e. PRODUCTS BUILT-UP OF STRATA OF FLAT OR NON-FLAT, e.g. CELLULAR OR HONEYCOMB, FORM
    • B32B33/00—Layered products characterised by particular properties or particular surface features, e.g. particular surface coatings; Layered products designed for particular purposes not covered by another single class
    • 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
    • C21D8/0205—Modifying the physical properties by deformation combined with, or followed by, heat treatment during manufacturing of plates or strips of ferrous alloys
    • 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
    • C21D8/00—Modifying the physical properties by deformation combined with, or followed by, heat treatment
    • C21D8/02—Modifying the physical properties by deformation combined with, or followed by, heat treatment during manufacturing of plates or strips
    • C21D8/0221—Modifying the physical properties by deformation combined with, or followed by, heat treatment during manufacturing of plates or strips characterised by the working steps
    • C21D8/0236—Cold rolling
    • 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
    • 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
    • C21D9/0081—Heat treatment, e.g. annealing, hardening, quenching or tempering, adapted for particular articles; Furnaces therefor for slabs; for billets
    • C—CHEMISTRY; METALLURGY
    • C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
    • C22C—ALLOYS
    • C22C37/00—Cast-iron alloys
    • 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
    • C22C38/004—Very low carbon steels, i.e. having a carbon content of less than 0,01%
    • 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
    • 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
    • C25—ELECTROLYTIC OR ELECTROPHORETIC PROCESSES; APPARATUS THEREFOR
    • C25D—PROCESSES FOR THE ELECTROLYTIC OR ELECTROPHORETIC PRODUCTION OF COATINGS; ELECTROFORMING; APPARATUS THEREFOR
    • C25D3/00—Electroplating: Baths therefor
    • C25D3/02—Electroplating: Baths therefor from solutions
    • C25D3/22—Electroplating: Baths therefor from solutions of zinc
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B32—LAYERED PRODUCTS
    • B32B—LAYERED PRODUCTS, i.e. PRODUCTS BUILT-UP OF STRATA OF FLAT OR NON-FLAT, e.g. CELLULAR OR HONEYCOMB, FORM
    • B32B2250/00—Layers arrangement
    • B32B2250/40—Symmetrical or sandwich layers, e.g. ABA, ABCBA, ABCCBA
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B32—LAYERED PRODUCTS
    • B32B—LAYERED PRODUCTS, i.e. PRODUCTS BUILT-UP OF STRATA OF FLAT OR NON-FLAT, e.g. CELLULAR OR HONEYCOMB, FORM
    • B32B2255/00—Coating on the layer surface
    • B32B2255/06—Coating on the layer surface on metal layer
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B32—LAYERED PRODUCTS
    • B32B—LAYERED PRODUCTS, i.e. PRODUCTS BUILT-UP OF STRATA OF FLAT OR NON-FLAT, e.g. CELLULAR OR HONEYCOMB, FORM
    • B32B2255/00—Coating on the layer surface
    • B32B2255/20—Inorganic coating
    • B32B2255/205—Metallic coating
    • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
    • Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
    • Y02E—REDUCTION OF GREENHOUSE GAS [GHG] EMISSIONS, RELATED TO ENERGY GENERATION, TRANSMISSION OR DISTRIBUTION
    • Y02E30/00—Energy generation of nuclear origin
    • Y02E30/30—Nuclear fission reactors

Definitions

  • the invention relates to a composite high-strength steel plate and a preparation method thereof, in particular to a high-strength steel composite galvanized sheet resistant to spot welding LME (Liquid Metal Embrittlement, liquid metal embrittlement) cracks and a preparation method thereof.
  • LME Solid Metal Embrittlement, liquid metal embrittlement
  • galvanizing processes including hot-dip galvanizing and electro-galvanizing are widely used.
  • the application of galvanized high-strength steel in the automotive field inevitably requires the use of joining technology.
  • the subsequent thermal processing of galvanized high-strength steel, such as hot stamping and resistance spot welding is prone to liquid metal embrittlement LME phenomenon, which becomes galvanized high-strength steel.
  • LME cracks The characteristic of LME cracks is that when the base metal is in contact with other types of liquid metal, that is, the melted galvanized layer, under the action of external stress or internal stress caused by restraint, thermal expansion, phase change, etc., the liquid metal will be along the base metal. The grain boundary of the material infiltrates, and in severe cases, cracks are formed, resulting in a decrease in the plasticity of the base metal.
  • the contact between base metal and liquid metal sensitive to LME, stress and suitable temperature range are the three necessary conditions for the formation of LME cracks.
  • High-strength steel galvanized sheets can meet the above three conditions at the same time during resistance spot welding. Therefore, high-strength steel plating
  • the problem of LME cracks in spot welding of zinc sheets is particularly serious.
  • the general characteristics of these steel types are retained austenite, high strength, and relatively high carbon, silicon, and manganese contents. Among them, the second-generation AHSS and the third-generation AHSS are most sensitive
  • Chinese invention patent CN201610963996.5 discloses a method of resistance spot welding of galvanized high-strength steel with good joint performance, using three welding pulses in one spot welding cycle; the first welding pulse and the second welding pulse are used to generate nugget And suppress the formation of LME cracks, wherein, the first welding pulse generates a nugget with a diameter of 3.75T1/2-4.25T1/2, T is the plate thickness; the second welding pulse makes the nugget grow slowly; the third welding pulse is slow Cold pulse, used to improve the plasticity of solder joints.
  • This method optimizes the spot welding process to minimize the time and degree of the existence of the necessary conditions to induce LME in the spot welding joint, but it cannot completely eliminate the cause of LME.
  • Chinese invention patent CN 201810819361.7 discloses a multi-layer steel including a core formed of phase transformation-induced plasticity (TRIP) steel and a method for reducing embrittlement of liquid metals.
  • a decarburized layer is located on at least one side of the core exterior.
  • the decarburized layer has a reduced carbon content relative to the core.
  • the zinc-based layer is located on the outside of the decarburized layer.
  • the decarburized layer can consist of at least 80% ferrite, allowing for a reduction or mitigation of LME. This method can only alleviate the problem of LME cracks to a certain extent, and there are problems such as the thickness and uniformity of the decarburized layer are not easy to control, and the surface properties of the base metal are unstable.
  • Chinese invention patent CN201780080831.6 discloses a multilayer galvanized alloy steel with excellent spot weldability and corrosion resistance.
  • the multilayer galvanized alloy steel includes base iron and a multilayer coating formed on the base iron.
  • the multilayer coating Each coating layer is any one of Zn coating layer, Mg coating layer and Zn-Mg alloy coating layer, relative to the total weight of the multi-layer coating layer, the weight ratio of Mg contained in the multi-layer coating layer is 0.13 to 0.24.
  • the adhesion between the coating and the substrate is difficult to ensure, and due to the complex phase transition of the Zn-Mg alloy, it is difficult to control the stability and uniformity of the coating.
  • One of the objectives of the present invention is to provide a high-strength steel composite galvanized sheet that is resistant to spot welding LME cracks, has lower spot welding LME sensitivity, and improves the resistance spot welding performance of the high-strength steel composite galvanized sheet.
  • the second object of the present invention is to provide a method for preparing a high-strength steel composite galvanized sheet resistant to spot welding LME cracks, which can reduce the high-strength steel composite coating through composite rolling of low-carbon steel composite layers while ensuring the performance of the base metal.
  • the spot welding LME sensitivity of the zinc plate can alleviate the problem of spot welding LME cracks.
  • a high-strength steel composite galvanized sheet resistant to spot welding LME cracks including a high-strength steel main body, a low-carbon steel composite layer and a galvanized layer; two low-carbon steel composite layers are respectively composite-rolled on the two surfaces of the high-strength steel main body
  • a galvanized layer is formed on the surface of at least one low-carbon steel composite layer to form a high-strength steel composite galvanized sheet.
  • the main body of the high-strength steel mentioned is a high-strength steel sensitive to spot welding LME, which may contain C, Si and Mn, may also contain Ti and Cr, and may optionally contain one of elements such as Nb, B and Al.
  • LME high-strength steel sensitive to spot welding
  • the balance is Fe and unavoidable impurities such as P and S.
  • in terms of mass percentage, in the high-strength steel body C ⁇ 0.10%, Mn ⁇ 1.0%, and Si ⁇ 0.07%. In some embodiments, in terms of mass percentage, in the high-strength steel body, C ⁇ 0.14%, Mn ⁇ 1.5%, Si ⁇ 0.4%. In some embodiments, in terms of mass percentage, in the high-strength steel body, C: 0.14-0.60%, Mn: 1.5-16%, and Si: 0.07-2.0%. In some embodiments, in terms of mass percentage, in the high-strength steel body, C: 0.14-0.30%, Mn: 1.5-3.5%, and Si: 0.4-2.0%.
  • the content of Ti can be ⁇ 0.01%, such as 0.01-0.10% or 0.01-0.05%; the content of Cr can be ⁇ 0.01%, such as 0.01-0.10% or 0.01-0.05% .
  • the high strength steel may further contain 0-0.06% Nb, 0-0.005% B and 0-2.0% Al.
  • the content of impurity P in high strength steel is ⁇ 0.01%, and the content of S is ⁇ 0.01%.
  • the high-strength steel of the present invention contains C: 0.1-0.3%, Si: 0.4-2.50%, Mn: 1.0-11.0%, and Al: 0-2.0%.
  • high-strength steel refers to steel with tensile strength ⁇ 780 MPa, preferably ⁇ 980 MPa, more preferably ⁇ 1180 MPa.
  • the high-strength steel used herein has a tensile strength of 780-1500 MPa, preferably 1180-1500 MPa.
  • the invention may be practiced using high strength steels well known in the art.
  • Exemplary high-strength steels may be selected from one or more of QP steel, TRIP steel, DH steel, 7Mn steel, 10Mn steel, and MS steel.
  • An exemplary QP steel may contain C: 0.1-0.25%, Si: 0.4-2.50%, Mn: 1.50-3.00%, and Al: 0.03-1.10%.
  • An exemplary TRIP steel may contain C: 0.15-0.3%, Si: 0.6-2.0%, Mn: 1.6-2.5%, Al: 0.02-0.90%.
  • An exemplary DH steel may contain C: 0.12-0.21%, Si: 0.3-0.9%, Mn: 1.6-2.5%, Al: 0.02-0.60%.
  • An exemplary 7Mn steel may contain C: 0.1-0.3%, Si: 0.1-2.0%, Mn: 6-8%, Al: 1-2%.
  • An exemplary 10Mn steel may contain C: 0.1-0.3%, Si: 0.1-2.0%, Mn: 9-11%, Al: 1-2%.
  • An exemplary MS steel may contain C: 0.1-0.3%, Si: 0.1-0.5%, Mn: 1.0-1.8%. These steels may contain components well known in the art for such steels.
  • the steel used in the high-strength steel body is a high-strength steel sensitive to spot welding LME.
  • the high-strength steel body contains C ⁇ 0.14%, Mn ⁇ 1.5%, Si ⁇ 0.4%, anti- Tensile strength ⁇ 780MPa.
  • the steel used in the low-carbon steel composite layer is low-carbon steel that is not sensitive to spot welding LME, and the low-carbon steel contains C: ⁇ 0.1% and Mn: ⁇ 1.1% by mass percentage.
  • the low-carbon steel composite layer contains C and Mn in terms of mass percentage, and the C content is ⁇ 0.1%, the Mn content is ⁇ 0.7%, and the tensile strength is ⁇ 590 MPa.
  • the low carbon steel contains C: 0.001-0.1% and Mn: 0.1-1.1% by mass percentage.
  • the low carbon steel contains C: 0.001-0.1%, Si: 0.001-0.50%, Mn: 0.1-0.1.1%, Nb: 0-0.02%, Ti: 0 ⁇ 0.025%, Ni: 0 ⁇ 0.025%, Cr: 0 ⁇ 0.05%, P: ⁇ 0.05%, and the balance is Fe and unavoidable impurities.
  • the low carbon steel contains C: 0.001-0.08%, Si: 0.001-0.05%, Mn: 0.1-0.7%, Nb: 0-0.02%, Ti: 0-0.025% by mass percentage. %, Ni: 0-0.025%, Cr: 0-0.05%, P: ⁇ 0.05%, and the balance is Fe and unavoidable impurities.
  • the low-carbon steel can be selected from IF steel, aluminum-killed steel, cold-rolled carbon structural steel, phosphorus-added high-strength steel, bake-hardening steel (BH steel) and low-alloy steel known in the art one or more of .
  • An exemplary IF steel may contain C: 0.001-0.01% and Mn: 0.10-1.00%.
  • An exemplary aluminum killed steel may contain C: 0.01-0.1% and Mn: 0.1-0.5%.
  • An exemplary BH steel may contain C: 0.002-0.1% and Mn: 0.10-1.00%.
  • An exemplary low alloy steel may contain C: 0.02-0.1%, Mn: 0.5-1.1%, and Si: 0.05-0.5%.
  • the tensile strength of the low carbon steel used in the present invention is in the range of 150-590 MPa. In some embodiments, the low carbon steel used in the present invention has a tensile strength in the range of 150-340 MPa.
  • A is the percentage of the original slab thickness of one layer of low-carbon steel composite layer to the total thickness of the slab
  • C is the percentage of the original slab thickness of the other low-carbon steel composite layer to the total thickness of the slab
  • the total billet is the total thickness of the original slab of the high-strength steel body and two low-carbon steel composite layers
  • L is the tensile strength of one low-carbon steel composite layer after annealing
  • N is the tensile strength of the other low-carbon steel composite layer after annealing
  • M is the tensile strength of the high-strength steel main body after annealing
  • T is the target tensile strength of the high-strength steel composite galvanized sheet
  • the unit of the tensile strength is MPa
  • the unit of the thickness is micron.
  • the thicknesses of the two low-carbon steel composite layers may be the same or different.
  • compositions of the two low-carbon steel composite layers can be the same or different.
  • each low-carbon steel composite layer is 10-200 ⁇ m, preferably 20-200 ⁇ m.
  • the thickness of the galvanized layer is 4-26 ⁇ m.
  • the preferred numerical range of A:B and C:B is 1:35.5-1:5.
  • the spot welding LME crack resistance performance of the high-strength steel composite galvanized sheet is as follows: there is no LME crack in the joint before welding spatter occurs, and the length of Type A LME crack in the joint after welding spatter does not exceed 10% of the thickness of the plate, and the number does not exceed 10%. More than 6, the length of TypeD LME cracks shall not exceed 3% of the plate thickness, and the number shall not exceed 3, and there shall be no TypeB and TypeC LME cracks.
  • the yield strength of the high-strength steel composite galvanized sheet is ⁇ 680 MPa
  • the tensile strength is ⁇ 980 MPa
  • the elongation is ⁇ 12%.
  • a preparation method of a high-strength steel composite galvanized sheet resistant to spot welding LME cracks comprising the following steps:
  • Step 1 Take the original slab of the high-strength steel main body and the original slab of the two-layer low-carbon steel composite layer, and attach the original slab of the two-layer low-carbon steel composite layer to the two surfaces of the original slab of the high-strength steel main body , and weld the edge of the original slab of the two-layer low-carbon steel composite layer with the edge of the original slab of the high-strength steel main body to form a total assembly;
  • Step 2 Through the thick plate blanking process, the total billet is heated and then initially rolled to reduce the thickness of the total billet, and then hot-rolled, pickled, cold-rolled, and annealed in sequence to make the original slab of the high-strength steel body and The original slabs of the two low-carbon steel composite layers are metallurgically bonded to form a billet with a tensile strength of T;
  • Step 3 Coating a galvanized layer on at least one surface of the blank to form a high-strength steel composite galvanized sheet.
  • step 1 before the original slabs of the two-layer low-carbon steel composite layer 2 and the original slab of the high-strength steel main body 1 are stacked, it is necessary to attach the high-strength steel main body 1 and the two-layer low-carbon steel composite layer 2 Sand and clean surfaces.
  • the method for coating the galvanized layer includes hot dipping or electroplating.
  • an exemplary hot rolling includes: heating the billet to 1200-1280°C, hot rolling after holding the heat for 0.5-4 hours, finishing rolling at a temperature of 850-1000°C, and then cooling to 400-400- Coil after 650°C.
  • the deformation of cold rolling can usually be controlled at 35-75%, such as 50-75%.
  • Exemplary annealing may include: heating to the soaking temperature at a rate of 1-20°C/s, the soaking temperature is 800-830°C, the soaking time is 30-240 seconds, and then heating at a rate of 2-20°C/s ( For example, cooling at a speed of 3-10 °C/s) to 650-750 °C, then cooling at a speed of 20-80 °C/s to 250-350 °C and keeping it warm for 10-120 seconds.
  • heat to the soaking temperature at a rate of 1-20°C/s is 800-830°C
  • the soaking time is 30-180 seconds
  • heat at a rate of 3-10°C/s Cool to 650-750°C, then cool to 280-300°C at a rate of 20-80°C/s and hold for 10-120 seconds, then heat to 450-470°C at a rate of 5-20°C/s and hold for 200- 300 seconds.
  • Exemplary hot-dip galvanizing includes: a galvanizing temperature of 440-500° C., and a galvanizing time of 5-200 seconds. After galvanizing, cool to room temperature at a cooling rate of not less than 20°C/s.
  • suitable hot rolling, pickling, cold rolling, annealing, and hot-dip/electroplating processes can be selected according to the high-strength steel and low-carbon steel used.
  • the present invention has the following beneficial effects:
  • the low-carbon steel composite layer plays a barrier role during spot welding to avoid liquid zinc along the The grain boundary penetrates into the base metal of the high-strength steel body, thereby fundamentally solving the problem of spot welding LME cracks in the high-strength steel body. While ensuring the mechanical properties of the base metal, it has good resistance spot welding performance and has extremely low spot welding LME sensitivity.
  • the low-carbon steel composite layer is composite-rolled on the surface of the high-strength steel main body, and liquid zinc is prevented from infiltrating into the base material along the grain boundary during spot welding, which reduces the spot-welding LME sensitivity of the high-strength steel composite galvanized sheet, effectively
  • spot welding LME cracks is avoided, the problem of spot welding LME cracks is alleviated, the resistance spot welding performance of the high-strength steel main body is improved, and the mechanical properties of the spot welding joints are significantly improved.
  • Fig. 1 is the cross-sectional view of the high-strength steel composite galvanized sheet resistant to spot welding LME cracks of the present invention.
  • Fig. 2 is the spot welding LME evaluation result (crack length) of the high-strength steel composite galvanized sheet in Example 1 of the spot-welded LME crack-resistant high-strength steel composite galvanized sheet of the present invention.
  • Fig. 3 is the spot welding LME evaluation result (number of cracks) of the high-strength steel composite galvanized sheet in Example 1 of the spot-welded LME crack-resistant high-strength steel composite galvanized sheet of the present invention.
  • FIG. 4 is the spot welding LME evaluation result (crack length) of the comparative example in Example 1.
  • FIG. 4 is the spot welding LME evaluation result (crack length) of the comparative example in Example 1.
  • Fig. 5 is the high-strength steel composite galvanized plate embodiment 1 of spot welding LME crack resistance of the present invention, and the spot welding joint is hard Degree distribution map, where, Represents the hardness distribution curve of the spot welded joint of the comparative example, Represent the hardness distribution curve of the spot welded joint of the high-strength steel composite galvanized sheet of Example 1.
  • composition of the steel involved in this article complies with the composition range specified in GB/T 13304.1-2008.
  • a kind of high-strength steel composite galvanized sheet of anti-spot welding LME crack including high-strength steel main body 1, low-carbon steel composite layer 2 and galvanized layer 3; Two layers of low-carbon steel composite layer 2 are composite rolled Manufactured on both surfaces of the high-strength steel main body 1, at least one low-carbon steel composite layer 2 is formed with a galvanized layer 3 on the surface to form a high-strength steel composite galvanized sheet.
  • Different steel grades have different sensitivities to spot-welded LME, and spot-welded LME cracks occur on the surface of galvanized high-strength steel. The crack is not sensitive, which fundamentally solves the occurrence of spot welding LME cracks.
  • the high-strength steel main body 1 is a high-strength steel sensitive to spot welding LME. In terms of mass percentage, the high-strength steel main body 1 contains C ⁇ 0.14%, Mn ⁇ 1.5%, Si ⁇ 0.4%, and the rest is Fe, other alloy elements and Impurity elements, tensile strength ⁇ 780MPa.
  • the high-strength steel main body 1 can be any high-strength steel sensitive to spot welding LME, such as QP (Quenching and Partitioning, that is, quenching and partitioning steel), TRIP (transformation induced plasticity steel, that is, transformation induced plasticity steel), TWIP (twinning induced plasticity steel) , twin-induced plasticity steel), DH (dual-phase high ductility steel, high ductility dual-phase steel), 7Mn (Fe-7%Mn-0.3%C-2%Al), 10Mn (Fe-10%Mn- 0.3%C-2%Al), DP (dual-phase, that is, dual-phase steel), MS (Martensitic Steel, that is, martensitic steel) and other steel types.
  • QP Quenching and Partitioning steel
  • TRIP transformation induced plasticity steel
  • TWIP twinning induced plasticity steel
  • DH dual-phase high ductility steel, high ductility dual-phase steel
  • the low-carbon steel composite layer 2 is low-carbon steel insensitive to spot welding LME, and the low-carbon steel composite layer 2 contains C and Mn in terms of mass percentage, and the C content is ⁇ 0.1%, and the Mn content is ⁇ 0.7% , tensile strength ⁇ 590MPa level, such as IF (interstitial-free steel, ie interstitial-free steel), aluminum killed steel, BH steel (Bake Hardenable steel, ie bake hardening steel), low alloy steel.
  • A is the percentage of the original slab thickness of one layer of low-carbon steel composite layer 2 in the total thickness of the blanks
  • C is the percentage of the original slab thickness of the other layer of low-carbon steel composite layer 2 in the total thickness of the blanks
  • B is the percentage of the original slab of the high-strength steel main body 1 to the total thickness of the blank assembly
  • A+B+C 100%.
  • the total billet is the main body of high-strength steel 1 and the total original slab thickness of the two mild steel clad plies 2.
  • L is the tensile strength of one low-carbon steel composite layer 2 after annealing
  • N is the tensile strength of the other low-carbon steel composite layer 2 after annealing
  • M is the tensile strength of the high-strength steel main body 1 after annealing.
  • T is the target tensile strength of the high-strength steel composite galvanized sheet.
  • each low-carbon steel composite layer 2 is 10-200 ⁇ m.
  • the thicknesses of the two low-carbon steel composite layers 2 on both sides of the high-strength steel body 1 may be the same or different.
  • the thickness of the galvanized layer 3 is 4-26 ⁇ m.
  • a preparation method of a high-strength steel composite galvanized sheet resistant to spot welding LME cracks comprising the following steps:
  • Step 1 Take the original slab of the high-strength steel main body 1 and the original slab of the two-layer low-carbon steel composite layer 2, and attach the original slabs of the two-layer low-carbon steel composite layer 2 to the original slab of the high-strength steel main body 1 On the two surfaces, the edge of the original slab of the two-layer low-carbon steel composite layer 2 is welded to the edge of the original slab of the high-strength steel main body 1 to form a total assembly.
  • the bonding surfaces of the high-strength steel main body 1 and the two low-carbon steel composite layers 2 need to be polished and cleaned, to ensure smoothness.
  • Step 2 Through the thick plate blanking process, the overall billet is heated and then preliminarily rolled to reduce the thickness of the total billet, and then follow-up hot rolling, pickling, cold rolling, annealing and other processes are carried out in sequence to make the high-strength steel body 1
  • the original slab of the two-layer low-carbon steel composite layer 2 is metallurgically bonded to form a blank with a tensile strength of T. Processes such as preliminary rolling, hot rolling, pickling, cold rolling, and annealing all adopt existing production processes, and will not be repeated here.
  • Step 3 hot-dip, electro-dip or other methods are used to coat the galvanized layer 3 on at least one surface of the blank to form a high-strength steel composite galvanized sheet.
  • the galvanized layer 3 can be coated by hot-dip, electroplating or other existing processes, which will not be repeated here.
  • the high-strength steel clad galvanized sheet of the present invention adopts the Rapid LME Test Procedure for Coated Sheet Steels V2.0 standard issued by the North American Automobile/Steel Partnership Organization (A/SP) to carry out spot welding LME susceptibility assessment, in this standard, according to crack
  • the cracks are divided into four categories: TypeA, TypeB, TypeC, and TypeD.
  • TypeA cracks are located in the contact area between the end of the spot welding electrode and the steel plate on the upper and lower surfaces of the spot welding joint.
  • This standard requires TypeA cracks before welding spatter occurs.
  • the crack length must be ⁇ 10% of the plate thickness.
  • Type A cracks after welding spatter This standard has no requirements for the length of Type A cracks after welding spatter occurs; Type B cracks are located in the non-contact area between the spot welding electrode and the steel plate on the upper and lower surfaces of the spot welding joint. The length of Type B cracks at the front and rear must be ⁇ 5% of the plate thickness; the Type C cracks are located in the contact area where the upper and lower steel plates overlap in the spot welding joint. This standard requires that the length of the Type C cracks before and after welding spatter must be ⁇ 5% of the plate thickness %;TypeD Type D cracks are located in the shoulder area of the indentation on the upper and lower surfaces of the spot welded joint, and the welding thickness deformation in this area is the largest. The standard requires that the length of Type D cracks before welding spatter must be ⁇ 5% of the plate thickness, and the length of Type D cracks after welding spatter must be ⁇ 10% of plate thickness.
  • the high-strength steel composite galvanized sheet of the present invention has good resistance to LME cracks in resistance spot welding: there is no LME crack in the joint before welding spatter occurs, and the length of Type A LME crack in the joint does not exceed 10% of the plate thickness after welding spatter occurs. And the number does not exceed 6, the length of Type D LME cracks does not exceed 3% of the plate thickness, and the number does not exceed 3, and there are no Type B and Type C LME cracks.
  • the basic welding performance and the mechanical properties of the base metal of the high-strength steel composite galvanized sheet of the present invention meet the application requirements in related fields.
  • the original slab of QP1180 (as high-strength steel main body 1), by mass percentage, the original slab of high-strength steel main body 1 comprises: 0.18% of C, 1.67% of Si, 2.73% of Mn, 0.0089% of P, 0.0009% of S, 0.02% of Ti, 0.03% of Cr, the balance of iron and unavoidable impurity elements.
  • the original slab of the low-carbon steel composite layer 2 includes: 0.0015% of C, 0.002% of Si, 0.114% of Mn, 0.0119% P, 0.0044% S, balance iron and unavoidable impurities.
  • the original slab thicknesses of the two low-carbon steel composite layers 2 are the same, 24 mm, and the original slab thickness of the high-strength steel main body 1 is 182 mm.
  • the thickness ratio of the original slab of the high-strength steel main body 1 to the original slab (one piece) of the low-carbon steel composite layer 2 is 7.5:1.
  • B 79%
  • M 1250MPa
  • T 1019MPa.
  • the original slabs (with the same thickness) of the two-layer low-carbon steel composite layer 2 are composite-rolled on the original slabs of the high-strength steel main body 1 through the process of billet assembly-thick plate blanking-hot rolling-pickling-cold rolling-annealing On the two surfaces of the blank, the blank is obtained, and the galvanized layer 3 is plated on the two surfaces of the blank by hot-dip galvanizing to form a high-strength steel composite galvanized sheet.
  • the specific process is as follows:
  • Hot rolling Heat the billet to 1200°C, heat it for 0.5 hours and then hot-roll it, the final rolling temperature is 850°C, then cool it to 400°C at a rate of 30°C and then coil it.
  • Hot-dip galvanizing the galvanizing temperature is 450°C, and the galvanizing time is 20 seconds. After galvanizing, the temperature is not less than 20°C/s cooling rate to room temperature.
  • the total thickness of the finally obtained high-strength steel composite galvanized sheet is 1.5 mm, the thickness of the two low-carbon steel composite layers 2 is about 160 ⁇ m, and the thickness of the galvanized layer 3 is about 8.6 ⁇ m.
  • the yield strength of the high-strength steel composite galvanized sheet is 696MPa, the tensile strength is 1074MPa, and the elongation at break is 15%, which meets the requirements of QP980GI.
  • the central layer structure is QP steel structure, containing martensite and retained austenite.
  • the rapid LME Test Procedure for Coated Sheet Steels V2.0 standard issued by A/SP is adopted for the high-strength steel clad galvanized sheet of the present embodiment to carry out the spot welding LME sensitivity assessment.
  • welding current ⁇ 11kA
  • welding spatter occurs.
  • the length of Type A LME crack in the joint after welding spatter does not exceed 10% of the plate thickness, and the number does not exceed 6, and the length of Type D LME crack does not exceed 3% of the plate thickness, and The number is not more than 3, and there are no TypeB and TypeC LME cracks, as shown in Figure 2 and Figure 3.
  • the high-strength steel composite galvanized sheet in this embodiment belongs to the spot welding LME low-sensitivity material.
  • the composition of the QP980GI material is: by mass percentage, including 0.18% of C, 1.8% of Si, 2.3% of Mn, 0.001% of S, 0.012% of P, 0.017% % Ti, the balance being iron and unavoidable impurities.
  • the mechanical properties of QP980GI material are: yield strength 687MPa, tensile strength 1068MPa, elongation at break 22%.
  • the Rapid LME Test Procedure for Coated Sheet Steels V2.0 standard is used to evaluate the LME sensitivity of spot welding of QP980GI material. When the welding current is ⁇ 10.5kA, welding spatter occurs.
  • Type A cracks after spatter are acceptable, in the comparison In the evaluation results of QP980GI, Type A cracks are not included, but there are Type D cracks whose length is close to 90% of the plate thickness and Type C cracks whose length exceeds 20% of the plate thickness, as shown in Figure 4.
  • the material is a spot welding LME sensitive material.
  • the weldable interval of the high-strength steel composite galvanized sheet of the present embodiment is 6.6kA-9.0kA, and the interval width is 2.4kA, and the weldable interval of the QP980GI material of the comparative example is 6.7kA-9.1kA, and the interval width 2.4kA; the solderable range of the two is equivalent.
  • the lower limit of the weldable range is the corresponding welding current when the nugget diameter is 5 mm
  • the upper limit of the weldable range is the corresponding minimum welding current when welding spatter occurs.
  • the joint TSS strength of this embodiment is 13.89kN (this joint TSS strength value is the average value after the test of 3 samples of this embodiment), the joint CTS strength is 6.22kN (this joint CTS strength value is this embodiment 3 The average value after the sample test), the joint TSS strength of the control example is 14.033kN (this joint TSS strength value is the average value after the 3 samples of the control example are tested), the joint CTS strength is 4.277kN (the joint CTS strength value is The average value of 3 samples of the control example after testing).
  • the joint TSS strength of this embodiment is comparable to that of the control example, but due to the existence of the composite rolling layer IF steel, the carbon equivalent in the nugget area is reduced, the hardness of the nugget is reduced, and the plasticity is improved. Therefore, this embodiment Compared with the control example, the CTS strength of the joint of the example is greatly improved.
  • the original slab of QP1180 (as high-strength steel main body 1), by mass percentage, the original slab of high-strength steel main body 1 comprises: 0.18% of C, 1.67% of Si, 2.73% of Mn, 0.0089% of P, 0.0009% of S, 0.02% of Ti, 0.03% of Cr, the balance of iron and unavoidable impurity elements.
  • the original slab of the low-carbon steel composite layer 2 includes: 0.0015% of C, 0.002% of Si, 0.114% of Mn, 0.0119% P, 0.0044% S, balance iron and unavoidable impurities.
  • the original slabs of the high-strength steel main body 1 and the original slabs of the low-carbon steel composite layer 2 are respectively according to the thickness ratio: 5.5:1, 7.5:1, 10.5: 1, 16.5: 1 and 35.5: 1 (this ratio is the ratio of the original slab thickness of high-strength steel main body 1 and the original slab of 1 low-carbon steel composite layer), carry out billet assembly, and according to the preparation method of the present invention , through the processes of billet formation-thick plate blanking-hot rolling-pickling-cold rolling-annealing-hot galvanizing, high-strength steel composite galvanized sheets with different thicknesses of low-carbon steel composite layers 2 are obtained, and each high-strength steel composite coating
  • Table 2 The detailed information of the zinc plate (1# ⁇ 5#) is shown in Table 2. The specific process is as follows:
  • Hot rolling heat the billet to 1230°C, heat it for 1 hour, and then hot-roll it.
  • the final rolling temperature is 920°C, and then it is cooled to 550°C at a rate of 50°C/s before coiling.
  • Annealing Heating to the soaking temperature at a rate of 10°C/s, the soaking temperature is 810°C, and the soaking time is 100 seconds, then cooled to 700°C at a rate of 7°C/s, and then heated at 50°C Cool to 300°C at a rate of 15°C/s and hold for 80 seconds, then heat to 470°C at a rate of 15°C/s and hold for 300 seconds.
  • Hot-dip galvanizing the galvanizing temperature is 480°C, and the galvanizing time is 100 seconds. After galvanizing, cool to room temperature at a cooling rate of not less than 20°C/s.
  • Table 2 High-strength steel composite galvanized sheets with low-carbon steel composite layer 2 of different thicknesses 1# ⁇ 5#
  • the original slab of QP1180 (as high-strength steel main body 1), by mass percentage, the original slab of high-strength steel main body 1 comprises: 0.18% of C, 1.67% of Si, 2.73% of Mn, 0.0089% of P, 0.0009% of S, 0.02% of Ti, 0.03% of Cr, the balance of iron and unavoidable impurity elements.
  • Cold-rolled carbon structural steel St37-2G, phosphorus-added high-strength steel HC220P, high-strength IF steel HC180Y, bake-hardened steel HC180B, and low-alloy high-strength steel HC300LA were used as the original slabs of the low-carbon steel composite layer 2, respectively.
  • the main chemical components of the original slabs of the above five low-carbon steel composite layers 2 are shown in Table 4 in terms of mass percentage, and the balance is iron and unavoidable impurity elements.
  • Table 4 Main chemical composition of original slabs for five mild steel clad layers 2
  • the original slabs of the high-strength steel main body 1 and the original slabs (1 piece) of the above-mentioned five kinds of low-carbon steel composite layers 2 are assembled according to the thickness ratio of 7.5:1, and according to the preparation method of the present invention, through the assembly - Thick plate blanking-hot rolling-pickling-cold rolling-annealing-hot galvanizing and other processes to obtain high-strength steel composite galvanized sheets 6# ⁇ 10# with different low-carbon steel composite layers 2, each high-strength steel composite coating
  • Table 5 Specific process such as Down:
  • Hot rolling heat the billet to 1250°C, heat it for 2 hours, and then hot-roll it.
  • the final rolling temperature is 980°C, and then it is cooled to 630°C at a rate of 90°C/s before coiling.
  • Hot-dip galvanizing the galvanizing temperature is 500°C, and the galvanizing time is 180 seconds. After galvanizing, cool to room temperature at a cooling rate of not less than 20°C/s.
  • Table 5 High-strength steel composite galvanized sheet with low-carbon steel composite layer 2 of different thicknesses 6# ⁇ 10#
  • the 6# ⁇ 10# high-strength steel clad galvanized sheets that were clad rolled in this embodiment were respectively adopted the Rapid LME Test Procedure for Coated Sheet Steels V2.0 standard issued by A/SP to conduct spot welding LME sensitivity assessment.
  • the results show that before the occurrence of welding spatter, there is no LME crack in the spot welding joints of 6# ⁇ 10# high-strength steel composite galvanized sheets; after the occurrence of welding spatter, there is no Type B
  • the length of Type A and Type C LME cracks shall not exceed 10% of the plate thickness, and the number of cracks shall not exceed 6; the length of Type D LME cracks shall not exceed 3% of the plate thickness, and the number of cracks shall not exceed 3.
  • the original slab of high-strength steel main body 1 includes: 0.18% of C, 0.48% of Si, 2.4% of Mn, 0.021 % Cr, 0.04% Nb, 0.02% Ti, 0.0004% B, 0.009% P, 0.001% S, 0.23% Al, the rest iron and unavoidable impurity elements.
  • Hot rolling heat the billet to 1280°C, heat it for 4 hours, and then hot-roll it.
  • the final rolling temperature is 950°C, and then it is cooled to 600°C at a rate of 80°C/s before coiling.
  • Annealing Heating to the soaking temperature at a rate of 15°C/s, the soaking temperature is 810°C, the soaking time is 200 seconds, the dew point temperature is controlled at 0°C and then cooled to 670°C at a rate of 10°C/s °C, then cooled to 320°C at a rate of 60°C/s and held for 80 seconds.
  • Hot-dip galvanizing the galvanizing temperature is 450°C, and the galvanizing time is 1600 seconds. After galvanizing, cool to room temperature at a cooling rate of not less than 20°C/s.
  • Table 7 High-strength steel composite galvanized sheets with low-carbon steel composite layer 2 of different thicknesses 11# ⁇ 15#
  • the 6# ⁇ 10# high-strength steel clad galvanized sheets that were clad rolled in this embodiment were respectively adopted the Rapid LME Test Procedure for Coated Sheet Steels V2.0 standard issued by A/SP to conduct spot welding LME sensitivity assessment.
  • the results show that before welding spatter, the spot welded joints of 11# ⁇ 15# high strength steel composite galvanized sheets have no LME cracks; after welding spatter, the spot welded joints of 11# ⁇ 15# high strength steel composite galvanized sheets have no Type B
  • the length of Type A and Type C LME cracks shall not exceed 10% of the plate thickness, and the number of cracks shall not exceed 6; the length of Type D LME cracks shall not exceed 3% of the plate thickness, and the number of cracks shall not exceed 3.

Landscapes

  • Chemical & Material Sciences (AREA)
  • Engineering & Computer Science (AREA)
  • Mechanical Engineering (AREA)
  • Materials Engineering (AREA)
  • Metallurgy (AREA)
  • Organic Chemistry (AREA)
  • Physics & Mathematics (AREA)
  • Thermal Sciences (AREA)
  • Crystallography & Structural Chemistry (AREA)
  • Chemical Kinetics & Catalysis (AREA)
  • Electrochemistry (AREA)
  • Laminated Bodies (AREA)
  • Heat Treatment Of Sheet Steel (AREA)

Abstract

本发明公开了一种抗点焊LME裂纹的高强钢复合镀锌板及其制备方法，该高强钢复合镀锌板包括高强钢主体(1)、低碳钢复合层(2)和镀锌层(3)；两层低碳钢复合层(2)分别复合轧制在高强钢主体(1)的两个表面上，至少一层低碳钢复合层(2)的表面形成有镀锌层(3)，构成高强钢复合镀锌板。本发明将低碳钢复合层复合轧制在高强钢主体的表面，在点焊焊接时避免液态金属沿晶界渗入母材内，降低了高强钢复合镀锌板的点焊LME敏感性，有效避免了点焊LME裂纹的发生，缓解点焊LME裂纹问题，提高了高强钢主体的电阻点焊性能，且点焊接头的力学性能得到明显提升。

Description

抗点焊LME裂纹的高强钢复合镀锌板及其制备方法 技术领域
本发明涉及一种复合高强钢板及其制备方法，尤其涉及一种抗点焊LME(Liquid Metal Embrittlement，即液态金属致脆)裂纹的高强钢复合镀锌板及其制备方法。
背景技术
汽车轻量化材料的研发和应用关系到车辆的节能、减排、安全、成本等诸多方面，对节约世界能源、自然资源和环境保护等方面具有重要意义，已成为汽车材料发展的主导方向。以AHSS(Advanced high strength steel，即先进高强钢)为代表的高强度材料已经充分体现出以降低汽车重量而实现节能目的的巨大潜力。
为了提高高强钢的耐腐蚀性能，包括热镀锌、电镀锌等形式的镀锌工艺被广为采用。镀锌高强钢在汽车领域的应用不可避免地需要用到连接技术，然而，镀锌高强钢后续热加工如热冲压和电阻点焊过程中易产生液态金属脆化LME现象，成为镀锌高强钢在汽车领域应用的主要障碍之一。
LME裂纹的特征在于母材在受外部施加的应力或由约束、热膨胀、相变等引起的内部应力作用下，与其它种类的液态金属即融化后的镀锌层接触时，液态金属会沿母材晶界渗入，严重时形成裂纹，从而造成母材塑性的降低。对LME敏感的母材与液态金属接触、应力、适合的温度区间是LME裂纹形成的3个必要条件，高强钢镀锌板在电阻点焊时，可同时满足上述3个条件，因此高强钢镀锌板的点焊LME裂纹问题尤为严重。这些钢种的普遍特点是含残余奥氏体，强度高，以及碳、硅、锰含量相对较高，其中，第二代AHSS及第三代AHSS对点焊LME最敏感。
中国发明专利CN201610963996.5公开了一种具有良好接头性能的镀锌高强钢电阻点焊方法，在一个点焊周期内使用三个焊接脉冲；第一焊接脉冲和第二焊接脉冲用于生成熔核并抑制LME裂纹生成，其中，第一焊接脉冲生成直径为3.75T1/2-4.25T1/2的熔核，T为板厚；第二焊接脉冲使熔核缓慢长大；第三焊接脉冲为缓 冷脉冲，用于提高焊点的塑性。该方法通过点焊工艺优化，尽量减少了点焊接头存在诱发LME产生必要条件的时间和程度，但无法彻底杜绝LME的诱因。
中国发明专利CN 201810819361.7公开了一种多层钢以及降低液态金属脆化的方法，多层钢包括由相变诱发塑性(TRIP)钢形成的芯。脱碳层位于芯外部的至少一侧。脱碳层相对于芯具有降低的碳含量。锌基层位于脱碳层的外部。脱碳层能够由至少80％铁素体组成，使得LME减少或减轻。该方法只能一定程度上减轻LME裂纹的问题，且存在脱碳层厚度及均匀性不易控制、母材表面性能不稳定等问题。
中国发明专利CN201780080831.6公开了一种点焊性及耐腐蚀性优异的多层镀锌合金钢材，多层镀锌合金钢材包含基材铁和基材铁上形成的多层镀层，多层镀层的每个镀层为Zn镀层、Mg镀层及Zn-Mg合金镀层中的任何一个，相对于多层镀层的总重量，多层镀层中含有的Mg重量之比为0.13至0.24。该方法中镀层和基板的附着力难以保证，且由于Zn-Mg合金相变复杂，镀层的稳定性和均匀性较难控制。
发明内容
本发明的目的之一在于提供一种抗点焊LME裂纹的高强钢复合镀锌板，具有较低的点焊LME敏感性，提高高强钢复合镀锌板的电阻点焊性能。
本发明的目的之二在于提供一种抗点焊LME裂纹的高强钢复合镀锌板的制备方法，能在保证母材性能的同时，通过低碳钢复合层的复合轧制降低高强钢复合镀锌板的点焊LME敏感性，缓解点焊LME裂纹问题。
本发明是这样实现的：
一种抗点焊LME裂纹的高强钢复合镀锌板，包括高强钢主体、低碳钢复合层和镀锌层；两层低碳钢复合层分别复合轧制在高强钢主体的两个表面上，至少一层低碳钢复合层的表面形成有镀锌层，构成高强钢复合镀锌板。
本文中，所述的高强钢主体为对点焊LME敏感的高强钢，其可含有C、Si和Mn，还可含有Ti和Cr，任选还可含有Nb、B和Al等元素中的一种或多种，余量为Fe和不可避免的杂质，如P和S。
在一些实施方案中，按质量百分比计，所述的高强钢主体中，C≥0.10％，Mn≥1.0％，Si≥0.07％。在一些实施方案中，按质量百分比计，所述的高强钢主体中， C≥0.14％，Mn≥1.5％，Si≥0.4％。在一些实施方案中，按质量百分比计，所述的高强钢主体中，C：0.14～0.60％，Mn：1.5～16％，Si：0.07～2.0％。在一些实施方案中，按质量百分比计，所述的高强钢主体中，C：0.14～0.30％，Mn：1.5～3.5％，Si：0.4～2.0％。
当高强钢主体中含有Ti和Cr时，Ti的含量可为≥0.01％，如0.01～0.10％或0.01～0.05％；Cr的含量可为≥0.01％，如0.01～0.10％或0.01～0.05％。
任选地，高强钢中还可含有0～0.06％的Nb、0～0.005％的B和0～2.0％的Al。
通常，高强钢中的杂质P的含量为≤0.01％，S的含量为≤0.01％。
在一些实施方案中，本发明的高强钢含有C：0.1～0.3％，Si：0.4～2.50％，Mn：1.0～11.0％和Al：0～2.0％。
本文中，高强钢指抗拉强度≥780MPa、优选≥980MPa、更优选≥1180MPa的钢。在一些实施方案中，本文所用的高强钢的抗拉强度为780～1500MPa，优选为1180～1500MPa。
可使用本领域熟知的高强钢来实施本发明。示例性的高强钢可选自QP钢、TRIP钢、DH钢、7Mn钢、10Mn钢和MS钢中的一种或多种。示例性的QP钢可含有C：0.1～0.25％，Si：0.4～2.50％，Mn：1.50-3.00％和Al：0.03～1.10％。示例性的TRIP钢可含有C：0.15～0.3％，Si：0.6～2.0％，Mn：1.6～2.5％，Al：0.02～0.90％。示例性的DH钢可含有C：0.12～0.21％，Si：0.3～0.9％，Mn：1.6～2.5％，Al：0.02～0.60％。示例性的7Mn钢可含有C：0.1～0.3％，Si：0.1-2.0％、Mn：6～8％，Al：1-2％。示例性的10Mn钢可含有C：0.1～0.3％，Si：0.1-2.0％、Mn：9～11％，Al：1-2％。示例性的MS钢可含有C：0.1～0.3％，Si：0.1～0.5％，Mn：1.0～1.8％。这些钢中可含有本领域熟知的这类钢所含的成分。
在一些实施方案中，所述的高强钢主体所用的钢为对点焊LME敏感的高强钢，按质量百分比计，高强钢主体含C≥0.14％，Mn≥1.5％，Si≥0.4％，抗拉强度≥780MPa。本文中，低碳钢复合层所用的钢为对点焊LME不敏感的低碳钢，按质量百分比计，低碳钢含有C：≤0.1％，Mn：≤1.1％。
在一些实施方案中，按质量百分比计，低碳钢复合层中含有C和Mn，且C含量≤0.1％，Mn含量≤0.7％，抗拉强度≤590MPa。
在一些实施方案中，按质量百分比计，低碳钢含有C：0.001～0.1％和Mn：0.1～1.1％。
在一些实施方案中，按质量百分比计，所述低碳钢含有C：0.001～0.1％，Si：0.001～0.50％，Mn：0.1～0.1.1％，Nb：0～0.02％，Ti：0～0.025％，Ni：0～0.025％，Cr：0～0.05％，P：≤0.05％，余量为Fe和不可避免的杂质。
在一些实施方案中，按质量百分比计，所述低碳钢含有C：0.001～0.08％，Si：0.001～0.05％，Mn：0.1～0.7％，Nb：0～0.02％，Ti：0～0.025％，Ni：0～0.025％，Cr：0～0.05％，P：≤0.05％，余量为Fe和不可避免的杂质。
在一些实施方案中，所述低碳钢可以选自本领域熟知的IF钢、铝镇静钢、冷轧碳素结构钢、加磷高强钢、烘烤硬化钢(BH钢)和低合金钢中的一种或多种。示例性的IF钢可含有C：0.001～0.01％和Mn：0.10-1.00％。示例性的铝镇静钢可含有C：0.01～0.1％和Mn：0.1-0.5％。示例性的BH钢可含有C：0.002～0.1％和Mn：0.10-1.00％。示例性的低合金钢可含有C：0.02～0.1％，Mn：0.5～1.1％和Si：0.05～0.5％。
在一些实施方案中，本发明所用的低碳钢的抗拉强度在150～590MPa的范围内。在一些实施方案中，本发明所用的低碳钢的抗拉强度在150～340MPa的范围内。
所述的高强钢主体的原始板坯厚度与低碳钢复合层的原始板坯厚度之间应满足关系式：L×A+M×B+N×C＝T；
其中，A为其中一层低碳钢复合层的原始板坯厚度占总组坯厚度的百分比，C为另一层低碳钢复合层的原始板坯厚度占总组坯厚度的百分比，B为高强钢主体的原始板坯占总组坯厚度的百分比，且A+B+C＝100％；总组坯为高强钢主体和两层低碳钢复合层的原始板坯总厚度；
L为其中一层低碳钢复合层退火后的抗拉强度，N为另一层低碳钢复合层退火后的抗拉强度，M为高强钢主体退火后的抗拉强度；
T为高强钢复合镀锌板的目标抗拉强度；
其中，所述抗拉强度的单位为MPa，所述厚度的单位为微米。
所述的高强钢复合镀锌板中，两层所述低碳钢复合层的厚度可以相同也可以不相同。
所述的高强钢复合镀锌板中，两层所述低碳钢复合层的组成可以相同也可以不同。
所述的高强钢复合镀锌板中，每层低碳钢复合层的厚度为10-200μm，优选为20-200μm。
所述的高强钢复合镀锌板中，镀锌层的厚度为4-26μm。
所述的高强钢复合镀锌板中，A∶B及C∶B优选的数值范围是1∶35.5-1∶5。
所述的高强钢复合镀锌板的抗点焊LME裂纹性能为：在发生焊接飞溅前接头无LME裂纹，在发生焊接飞溅后接头TypeA类LME裂纹长度不超过板厚的10％，且数量不超过6条，TypeD类LME裂纹长度不超过板厚的3％，且数量不超过3条，无TypeB类、TypeC类LME裂纹。
在一些实施方案中，所述高强钢复合镀锌板的屈服强度≥680MPa，抗拉强度≥980MPa，延伸率≥12％。
一种抗点焊LME裂纹的高强钢复合镀锌板的制备方法，包括以下步骤：
步骤1：取高强钢主体的原始板坯和两层低碳钢复合层的原始板坯，将两层低碳钢复合层的原始板坯贴合在高强钢主体原始板坯的两个表面上，并将两层低碳钢复合层的原始板坯边缘处与高强钢主体的原始板坯边缘处焊接，形成总组坯；
步骤2：通过厚板开坯工序将总组坯加热后进行初步轧制，降低总组坯的厚度，再依次进行热轧、酸洗、冷轧、退火，使高强钢主体的原始板坯与两层低碳钢复合层的原始板坯发生冶金结合，形成抗拉强度为T的坯料；
步骤3：在坯料的至少一个面上镀覆镀锌层，形成高强钢复合镀锌板。
所述的步骤1中，在两层低碳钢复合层2的原始板坯与高强钢主体1的原始板坯叠放前，需对高强钢主体1和两层低碳钢复合层2的贴合面进行打磨和清洁。
所述镀覆镀锌层的方法包括热镀或电镀。
上述热轧、酸洗、冷轧、退火、热镀和电镀可采用本领域熟知的方法实施。例如，示例性的热轧包括：将坯料加热至1200-1280℃，保温0.5～4小时后热轧，终轧温度850℃～1000℃，随后以30-100℃/s的速率冷却到400-650℃后进行卷取。
冷轧的变形量通常可控制在35～75％，如50～75％。
示例性的退火可包括：以1～20℃/s的速率加热至均热温度，均热温度为800-830℃，均热保温时间为30～240秒，然后以2～20℃/s(如3～10℃/s)的速度冷却到650～750℃，再以20～80℃/s的速度冷却到250～350℃并保温10～120秒。在一些实施方案中，以1～20℃/s的速率加热至均热温度，均热温度为800～830℃，均热保温时间为30～180秒，然后以3～10℃/s的速度冷却到650～750℃，再以20～80℃/s的速度冷却到280～300℃并保温10～120秒，随后以5～20℃/s的速率加热至450～470摄氏度并保温200～300秒。在一些实施方案中，以1～20℃/s的速率加热至均热温度，均热温度为810～830℃，均热保温时间为30～240秒，控制露点温度 为-50～20℃然后以2～20℃/s的速度冷却到650～720℃，再以20～80℃/s的速度冷却到250～350℃并保温10～120秒。
示例性的热镀锌包括：镀锌温度440～500℃，镀锌时间为5～200秒。镀锌后以不小于20℃/s的冷却速率冷却至室温。
应理解，可根据所使用的高强钢和低碳钢，选择合适的热轧、酸洗、冷轧、退火、热镀/电镀工艺。
本发明与现有技术相比，具有如下有益效果：
1、本发明由于在高强钢主体的两个表面复合轧制了对点焊LME裂纹不敏感的低碳钢复合层，在点焊时通过低碳钢复合层起到阻隔作用，避免液态锌沿晶界渗入高强钢主体母材，从而从根本上解决了高强钢主体的点焊LME裂纹的问题，在保证母材机械性能的同时，拥有良好的电阻点焊性能，且拥有极低的点焊LME敏感性。
2、本发明的高强钢复合镀锌板在点焊时，发生焊接飞溅前接头无LME裂纹，在发生焊接飞溅后接头TypeA类LME裂纹长度不超过板厚的10％，且数量少于6条，TypeD类LME裂纹长度不超过板厚的3％，且数量少于3条，无TypeB类、TypeC类LME裂纹，且其基本焊接性能及母材力学性能满足汽车制造等相关领域的应用要求。
本发明将低碳钢复合层复合轧制在高强钢主体的表面，在点焊焊接时避免液态锌沿晶界渗入母材内，降低了高强钢复合镀锌板的点焊LME敏感性，有效避免了点焊LME裂纹的发生，缓解点焊LME裂纹问题，提高了高强钢主体的电阻点焊性能，且点焊接头的力学性能得到明显提升。
附图说明
图1是本发明抗点焊LME裂纹的高强钢复合镀锌板的剖视图。
图2是本发明抗点焊LME裂纹的高强钢复合镀锌板实施例1中高强钢复合镀锌板的点焊LME评估结果(裂纹长度)。
图3是本发明抗点焊LME裂纹的高强钢复合镀锌板实施例1中高强钢复合镀锌板的点焊LME评估结果(裂纹数量)。
图4是实施例1中对照例的点焊LME评估结果(裂纹长度)。
图5是本发明抗点焊LME裂纹的高强钢复合镀锌板实施例1中点焊接头硬 度分布图，其中，表示对照例的点焊接头硬度分布曲线，表示实施例1高强钢复合镀锌板的点焊接头硬度分布曲线。
图中，1高强钢主体，2低碳钢复合层，3镀锌层。
具体实施方式
下面结合附图和具体实施例对本发明作进一步说明。如果没有单独的说明，本文所涉及的钢材成分符合GB/T 13304.1-2008所规定的成分范围。
请参见附图1，一种抗点焊LME裂纹的高强钢复合镀锌板，包括高强钢主体1、低碳钢复合层2和镀锌层3；两层低碳钢复合层2分别复合轧制在高强钢主体1的两个表面上，至少一层低碳钢复合层2的表面形成有镀锌层3，构成高强钢复合镀锌板。不同钢种对点焊LME的敏感性不同，而点焊LME裂纹是发生在镀锌高强钢的表面，故通过低碳钢复合层2的复合轧制使高强钢主体1的表面对点焊LME裂纹不敏感，从根本上解决了点焊LME裂纹的发生。
所述的高强钢主体1为对点焊LME敏感的高强钢，按质量百分比计，高强钢主体1含C≥0.14％，Mn≥1.5％，Si≥0.4％，其余为Fe、其它合金元素及杂质元素，抗拉强度≥780MPa。高强钢主体1可以是任何对点焊LME敏感的高强钢，例如QP(Quenching and Partitioning，即淬火配分钢)、TRIP(transformation induced plasticity steel，即相变诱导塑性钢)、TWIP(twinning induced plasticity steel，即孪生诱发塑性钢)、DH(dual-phase high ductility steel，即高延性双相钢)、7Mn(Fe-7％Mn-0.3％C-2％Al)、10Mn(Fe-10％Mn-0.3％C-2％Al)、DP(dual-phase，即双相钢)、MS(Martensitic Steel，即马氏体钢)等钢种。
所述的低碳钢复合层2为对点焊LME不敏感的低碳钢，按质量百分比计，低碳钢复合层2中含有C和Mn，且C含量≤0.1％，Mn含量≤0.7％，抗拉强度≤590MPa级，例如IF(interstitial-free steel，即无间隙原子钢)、铝镇静钢、BH钢(Bake Hardenable steel，即烘烤硬化钢)、低合金钢。
所述的高强钢主体1的原始板坯厚度与低碳钢复合层2的原始板坯厚度之间应满足关系式：L×A+M×B+N×C＝T。
其中，A为其中一层低碳钢复合层2的原始板坯厚度占总组坯厚度的百分比，C为另一层低碳钢复合层2的原始板坯厚度占总组坯厚度的百分比，B为高强钢主体1的原始板坯占总组坯厚度的百分比，且A+B+C＝100％。总组坯为高强钢主体 1和两层低碳钢复合层2的原始板坯总厚度。
L为其中一层低碳钢复合层2退火后的抗拉强度，N为另一层低碳钢复合层2退火后的抗拉强度，M为高强钢主体1退火后的抗拉强度。
T为高强钢复合镀锌板的目标抗拉强度。
所述的高强钢复合镀锌板中，每层低碳钢复合层2的厚度均为10-200μm。高强钢主体1两侧的两层低碳钢复合层2的厚度可以相同，也可以不同。
所述的高强钢复合镀锌板中，镀锌层3的厚度为4-26μm。
一种抗点焊LME裂纹的高强钢复合镀锌板的制备方法，包括以下步骤：
步骤1：取高强钢主体1的原始板坯和两层低碳钢复合层2的原始板坯，将两层低碳钢复合层2的原始板坯贴合在高强钢主体1原始板坯的两个表面上，并将两层低碳钢复合层2的原始板坯边缘处与高强钢主体1的原始板坯边缘处焊接，形成总组坯。
在两层低碳钢复合层2的原始板坯与高强钢主体1的原始板坯叠放前，需对高强钢主体1和两层低碳钢复合层2的贴合面进行打磨和清洁，以保证光洁度。
步骤2：通过厚板开坯工序将总组坯加热后进行初步轧制，降低总组坯的厚度，再依次进行后续的热轧、酸洗、冷轧、退火等工序，使高强钢主体1的原始板坯与两层低碳钢复合层2的原始板坯发生冶金结合，形成抗拉强度为T的坯料。初步轧制、热轧、酸洗、冷轧、退火等工艺均采用现有生产工艺，此处不再赘述。
步骤3：在坯料的至少一个面上通过热镀、电镀或其他方式镀覆镀锌层3，形成高强钢复合镀锌板。镀锌层3的镀覆可采用热镀、电镀或其他现有工艺，此处不再赘述。
对本发明的高强钢复合镀锌板采用北美汽车/钢铁伙伴组织(A/SP)发布的Rapid LME Test Procedure for Coated Sheet Steels V2.0标准进行点焊LME敏感性评估，在该标准中，根据裂纹的分布位置，将裂纹分为TypeA、TypeB、TypeC、TypeD四类，其中，TypeA类裂纹位于点焊接头上下表面中点焊电极端部与钢板的接触区域，该标准要求发生焊接飞溅前TypeA类裂纹长度需≤板厚10％，该标准对发生焊接飞溅后TypeA类裂纹长度无要求；TypeB类裂纹位于点焊接头上下表面中点焊电极与钢板的非接触区域，该标准要求无论发生焊接飞溅前、后TypeB类裂纹长度需≤板厚5％；TypeC类裂纹位于点焊接头中上下层钢板搭接的接触区域，该标准要求无论发生焊接飞溅前、后TypeC类裂纹长度需≤板厚5％；TypeD 类裂纹位于点焊接头上下表面压痕的肩部区域，该区域焊厚变形量最大，该标准要求发生焊接飞溅前TypeD类裂纹长度需≤板厚5％，发生焊接飞溅后TypeD类裂纹长度需≤板厚10％。
本发明的高强钢复合镀锌板具有良好的抗电阻点焊LME裂纹的性能：在发生焊接飞溅前接头无LME裂纹，在发生焊接飞溅后接头TypeA类LME裂纹长度不超过板厚的10％，且数量不超过6条，TypeD类LME裂纹长度不超过板厚的3％，且数量不超过3条，无TypeB类、TypeC类LME裂纹。同时，本发明的高强钢复合镀锌板的基本焊接性能及母材力学性能满足相关领域的应用要求。
实施例1
请参见附图1，取QP1180(作为高强钢主体1)的原始板坯，按质量百分比计，高强钢主体1的原始板坯包括：0.18％的C、1.67％的Si、2.73％的Mn、0.0089％的P、0.0009％的S、0.02％的Ti、0.03％的Cr、余量的铁和不可避免的杂质元素。
取IF钢DC04(作为低碳钢复合层2)的原始板坯，按质量百分比计，低碳钢复合层2的原始板坯包括：0.0015％的C、0.002％的Si、0.114％的Mn、0.0119％的P、0.0044％的S、余量铁和不可避免的杂质。
两层低碳钢复合层2的原始板坯厚度相同，均为24mm，高强钢主体1的原始板坯厚度为182mm。高强钢主体1的原始板坯与低碳钢复合层2的原始板坯(一块)的厚度比为7.5∶1，本实施例中，A＝C＝10.5％，L＝N＝150MPa，B＝79％，M＝1250MPa，T＝1019MPa。通过组坯-厚板开坯-热轧-酸洗-冷轧-退火工序，将两层低碳钢复合层2的原始板坯(厚度相同)复合轧制在高强钢主体1的原始板坯的两个表面上，得到坯料，并在坯料的两个表面上通过热镀锌的方式镀覆镀锌层3，形成高强钢复合镀锌板，具体工艺如下：
(1)热轧：将坯料加热至1200，保温0.5小时后热轧，终轧温度850℃，随后以30的速率冷却到400后进行卷取。
(2)冷轧：冷轧的变形量为50％。
(3)退火：以5℃/s的速率加热至均热温度，均热温度为800℃，均热保温时间为50秒，然后以3℃/s的速度冷却到650℃，再以20℃/s的速度冷却到280℃并保温20秒，随后以5℃/s的速率加热至450℃并保温200秒。
(4)热镀锌：镀锌温度450℃，镀锌时间为20秒。镀锌后以不小于20℃/s 的冷却速率冷却至室温。
最终获得的高强钢复合镀锌板的总厚度为1.5mm，两层低碳钢复合层2的厚度约160μm，镀锌层3的厚度约8.6μm。高强钢复合镀锌板的屈服强度为696MPa，抗拉强度为1074MPa，断裂延伸率为15％，满足QP980GI的要求，中心层组织为QP钢组织，含马氏体及残余奥氏体。
对本实施例复合轧制的高强钢复合镀锌板采用A/SP发布的Rapid LME Test Procedure for Coated Sheet Steels V2.0标准，进行点焊LME敏感性评估，当焊接电流≥11kA时发生焊接飞溅，在发生焊接飞溅前接头无LME裂纹，在发生焊接飞溅后接头TypeA类LME裂纹长度不超过板厚的10％，且数量不超过6条，TypeD类LME裂纹长度不超过板厚的3％，且数量不超过3条，无TypeB类、TypeC类LME裂纹，如图2和图3所示。根据该标准，本实施例的高强钢复合镀锌板属于点焊LME低敏感性材料。
将厚度为1.5mm的QP980GI材作为对照例，QP980GI材的成分为：按质量百分比计，包括0.18％的C、1.8％的Si、2.3％的Mn、0.001％的S、0.012％的P、0.017％的Ti，余量为铁和不可避免的杂质。QP980GI材的力学性能为：屈服强度687MPa、抗拉强度1068MPa、断裂延伸率22％。采用Rapid LME Test Procedure for Coated Sheet Steels V2.0标准对QP980GI材进行点焊LME敏感性评估，当焊接电流≥10.5kA时发生焊接飞溅，由于飞溅后TypeA型裂纹是可接受的，在作为对照的QP980GI的评估结果中，未将TypeA型裂纹计入，但有长度接近板厚90％的TypeD型裂纹和长度超过板厚20％的TypeC型裂纹，如图4所示。根据该标准，该材料属于点焊LME敏感性材料。
采用表1所列的点焊参数，对本实施例和对照例进行点焊基本性能实验，其点焊接头硬度分布如图5所示。
表1：点焊参数

从图5可知，本实施例的高强钢复合镀锌板的可焊区间为6.6kA-9.0kA，区间宽度为2.4kA，对照例的QP980GI材的可焊区间为6.7kA-9.1kA，区间宽度2.4kA；二者的可焊区间相当。其中可焊区间的下限为生成熔核直径为5mm时对应的焊接电流，可焊区间的上限为发生焊接飞溅时对应的最小焊接电流。相应的，在二者熔核直径均为5mm时，对两种样板的接头TSS(Tensile shear strength，即拉剪强度)强度及接头CTS(Cross tension strength，即十字拉伸强度)强度进行测试，本实施例的接头TSS强度为13.89kN(该接头TSS强度值为本实施例的3个样品测试后的平均值)，接头CTS强度为6.22kN(该接头CTS强度值为本实施例的3个样品测试后的平均值)，对照例的接头TSS强度为14.033kN(该接头TSS强度值为对照例的3个样品测试后的平均值)，接头CTS强度为4.277kN(该接头CTS强度值为对照例的3个样品测试后的平均值)。可见，本实施例的接头TSS强度相比与对照例相当，但由于复合轧制层IF钢的存在，降低了熔核区域的碳当量，使熔核的硬度降低，塑性得到提高，因此本实施例的接头CTS强度相比对照例有较大幅度的提升。
实施例2
请参见附图1，取QP1180(作为高强钢主体1)的原始板坯，按质量百分比计，高强钢主体1的原始板坯包括：0.18％的C、1.67％的Si、2.73％的Mn、0.0089％的P、0.0009％的S、0.02％的Ti、0.03％的Cr、余量的铁和不可避免的杂质元素。
取IF钢DC04(作为低碳钢复合层2)的原始板坯，按质量百分比计，低碳钢复合层2的原始板坯包括：0.0015％的C、0.002％的Si、0.114％的Mn、0.0119％ 的P、0.0044％的S、余量铁和不可避免的杂质。
将高强钢主体1的原始板坯与低碳钢复合层2的原始板坯(两侧低碳钢复合层2的原始板坯厚度相同)分别按厚度比为：5.5∶1、7.5∶1、10.5∶1、16.5∶1和35.5∶1(该比值为高强钢主体1的原始板坯厚度与1块低碳钢复合层原始板坯的比值)，进行组坯，并按本发明的制备方法，经组坯-厚板开坯-热轧-酸洗-冷轧-退火-热镀锌等工序，获得具有不同低碳钢复合层2厚度的高强钢复合镀锌板，各高强钢复合镀锌板(1#～5#)的详细信息如表2所示。具体工序如下：
(1)热轧：将坯料加热至1230℃，保温1小时后热轧，终轧温度920℃，随后以50℃/s的速率冷却到550℃后进行卷取。
(2)冷轧：冷轧的变形量为60％。
(3)退火：以10℃/s的速率加热至均热温度，均热温度为810℃，均热保温时间为100秒，然后以7℃/s的速度冷却到700℃，再以50℃/s的速度冷却到300℃并保温80秒，随后以15℃/s的速率加热至470℃并保温300秒。
(4)热镀锌：镀锌温度480℃，镀锌时间为100秒。镀锌后以不小于20℃/s的冷却速率冷却至室温。
表2：具有不同厚度的低碳钢复合层2的高强钢复合镀锌板1#～5#
对1#～5#高强钢复合镀锌板分别采用A/SP发布的Rapid LME Test Procedure for Coated Sheet Steels V2.0标准，进行点焊LME敏感性评估。结果表明在发生焊接飞溅前，1#～5#高强钢复合镀锌板点焊接头均无LME裂纹；在发生焊接飞溅后，1#～5#高强钢复合镀锌板点焊接头均无TypeB类、TypeC类LME裂纹，TypeA类 LME裂纹长度均不超过板厚的10％，且数量不超过6条，TypeD类LME裂纹长度均不超过板厚的3％，且数量不超过3条，详见表3。
表3：1#～5#高强钢复合镀锌板点焊接头发生飞溅后LME裂纹检测结果
实施例3
请参见附图1，取QP1180(作为高强钢主体1)的原始板坯，按质量百分比计，高强钢主体1的原始板坯包括：0.18％的C、1.67％的Si、2.73％的Mn、0.0089％的P、0.0009％的S、0.02％的Ti、0.03％的Cr、余量的铁和不可避免的杂质元素。
分别取冷轧碳素结构钢St37-2G、加磷高强钢HC220P、高强IF钢HC180Y、烘烤硬化钢HC180B、低合金高强钢HC300LA作为低碳钢复合层2的原始板坯。按质量百分比，上述五种低碳钢复合层2的原始板坯的主要化学成分见表4，余量为铁和不可避免的杂质元素。
表4：五种低碳钢复合层2的原始板坯主要化学成分
将高强钢主体1的原始板坯与上述五种低碳钢复合层2的原始板坯(1块)按厚度比7.5∶1进行组坯，并按本发明所述的制备方法，经组坯-厚板开坯-热轧-酸洗-冷轧-退火-热镀锌等工序，获得具有不同低碳钢复合层2的高强钢复合镀锌板6#～10#，各高强钢复合镀锌板(6#～10#)的详细信息如表5所示。具体工艺如 下：
(1)热轧：将坯料加热至1250℃，保温2小时后热轧，终轧温度980℃，随后以90℃/s的速率冷却到630℃后进行卷取。
(2)冷轧：冷轧的变形量为70％。
(3)退火：以20℃/s的速率加热至均热温度，均热温度为830℃，均热保温时间为160秒，然后以8℃/s的速度冷却到750℃，再以70℃/s的速度冷却到300℃并保温100秒，随后以15℃/s的速率加热至470℃并保温200秒。
(4)热镀锌：镀锌温度500℃，镀锌时间为180秒。镀锌后以不小于20℃/s的冷却速率冷却至室温。
表5：具有不同厚度的低碳钢复合层2的高强钢复合镀锌板6#～10#
对本实施例复合轧制的6#～10#高强钢复合镀锌板分别采用A/SP发布的Rapid LME Test Procedure for Coated Sheet Steels V2.0标准，进行点焊LME敏感性评估。结果表明在发生焊接飞溅前，6#～10#高强钢复合镀锌板点焊接头均无LME裂纹；在发生焊接飞溅后，6#～10#高强钢复合镀锌板点焊接头均无TypeB类、TypeC类LME裂纹，TypeA类LME裂纹长度均不超过板厚的10％，且数量不超过6条，TypeD类LME裂纹长度均不超过板厚的3％，且数量不超过3条。
实施例4
请参见图1，取DH980(作为高强钢主体1)的原始板坯，按质量百分比计，高强钢主体1的原始板坯包括：0.18％的C、0.48％的Si、2.4％的Mn、0.021％的Cr、0.04％的Nb、0.02％的Ti、0.0004％的B、0.009％的P、0.001％的S、0.23％的Al、余量的铁和不可避免的杂质元素。
分别取IF钢DC04、冷轧碳素结构钢St37-2G、加磷高强钢HC220P、高强IF 钢HC180Y、烘烤硬化钢HC180B作为低碳钢复合层2的原始板坯。按质量百分比，上述五种低碳钢复合层2的原始板坯的主要化学成分见表6，余量为铁和不可避免的杂质元素。
表6：五种低碳钢复合层2的原始板坯主要化学成分
将各复合层的板坯原材料按照比例轧制至符合7.5∶1的厚度(高强钢主体厚度与1块低碳钢板坯的的厚度比)备用；清理各复合层相邻的界面，去除氧化皮等杂质；焊接密封各复合层相接触的边界，并抽真空去除复合层之间的氧气，然后轧制复合组坯。经下述热轧、酸洗、冷轧、退火和热镀锌工序，获得具有不同低碳钢复合层2的高强钢复合镀锌板11#～15#，各高强钢复合镀锌板(11#～15#)的详细信息如表7所示。
(1)热轧：将坯料加热至1280℃，保温4小时后热轧，终轧温度950℃，随后以80℃/s的速率冷却到600℃后进行卷取。
(2)酸洗
(3)冷轧：冷轧的变形量为40％。
(4)退火：以15℃/s的速率加热至均热温度，均热温度为810℃，均热保温时间为200秒，控制露点温度为0℃然后以10℃/s的速度冷却到670℃，再以60℃/s的速度冷却到320℃并保温80秒。
(6)热镀锌：镀锌温度450℃，镀锌时间为1600秒。镀锌后以不小于20℃/s的冷却速率冷却至室温。
表7：具有不同厚度的低碳钢复合层2的高强钢复合镀锌板11#～15#

对本实施例复合轧制的6#～10#高强钢复合镀锌板分别采用A/SP发布的Rapid LME Test Procedure for Coated Sheet Steels V2.0标准，进行点焊LME敏感性评估。结果表明在发生焊接飞溅前，11#～15#高强钢复合镀锌板点焊接头均无LME裂纹；在发生焊接飞溅后，11#～15#高强钢复合镀锌板点焊接头均无TypeB类、TypeC类LME裂纹，TypeA类LME裂纹长度均不超过板厚的10％，且数量不超过6条，TypeD类LME裂纹长度均不超过板厚的3％，且数量不超过3条。
以上仅为本发明的较佳实施例而已，并非用于限定本发明的保护范围，因此，凡在本发明的精神和原则之内所作的任何修改、等同替换、改进等，均应包含在本发明的保护范围之内。

Claims (14)

  1. 一种抗点焊LME裂纹的高强钢复合镀锌板，其特征是：包括高强钢主体(1)、低碳钢复合层(2)和镀锌层(3)；其中，两层低碳钢复合层(2)分别复合轧制在高强钢主体(1)的两个表面上，且至少一层低碳钢复合层(2)的表面形成有镀锌层(3)，构成高强钢复合镀锌板。
  2. 根据权利要求1所述的抗点焊LME裂纹的高强钢复合镀锌板，其特征是：所述的高强钢主体(1)为对点焊LME敏感的高强钢，其抗拉强度≥780MPa，优选≥980MPa、更优选≥1180MPa的钢；优选地，所述高强钢的抗拉强度为780～1500MPa，优选为1180～1500MPa。
  3. 根据权利要求2所述的抗点焊LME裂纹的高强钢复合镀锌板，其特征是：按质量百分比计，所述高强钢含：C≥0.1％，如C≥0.14％，Mn≥1.0％，如Mn≥1.5％，Si≥0.07％，优选Si≥0.4％；优选地，按质量百分比计，所述的高强钢含有C：0.14～0.60％，Mn：1.5～16％，Si：0.07～2.0％；更优选地，按质量百分比计，所述的高强钢含有C：0.14～0.30％，Mn：1.5～3.5％，Si：0.4～2.0％。
  4. 根据权利要求2所述的抗点焊LME裂纹的高强钢复合镀锌板，其特征是：按质量百分比计，所述高强钢含有C：0.1～0.3％，Si：0.4～2.50％，Mn：1.0～11.0％和Al：0～2.0％。
  5. 根据权利要求2所述的抗点焊LME裂纹的高强钢复合镀锌板，其特征是：所述高强钢选自QP钢、TRIP钢、DH钢、7Mn钢、10Mn钢和MS钢中的一种或多种。
  6. 根据权利要求1-5中任一项所述的抗点焊LME裂纹的高强钢复合镀锌板，其特征是：低碳钢复合层(2)为对点焊LME不敏感的低碳钢，按质量百分比计，低碳钢含有C和Mn，且C含量≤0.1％，Mn含量≤1.1％，如Mn≤0.7％，抗拉强度≤590MPa，如150～590MPa或150～340MPa；
    优选地，按质量百分比计，低碳钢含有C：0.001～0.1％和Mn：0.1～1.1％。
  7. 根据权利要求6所述的抗点焊LME裂纹的高强钢复合镀锌板，其特征是：按质量百分比计，所述低碳钢含有C：0.001～0.1％，Si：0.001～0.50％，Mn：0.1～0.1.1％，Nb：0～0.02％，Ti：0～0.025％，Ni：0～0.025％，Cr：0～0.05％，P：≤0.05％，余量为Fe和不可避免的杂质；或按质量百分比计，所述低碳钢含有C：0.001～0.08％， Si：0.001～0.05％，Mn：0.1～0.7％，Nb：0～0.02％，Ti：0～0.025％，Ni：0～0.025％，Cr：0～0.05％，P：≤0.05％，余量为Fe和不可避免的杂质。
  8. 根据权利要求6所述的抗点焊LME裂纹的高强钢复合镀锌板，其特征是：所述低碳钢选自IF钢、铝镇静钢、冷轧碳素结构钢、加磷高强钢、烘烤硬化钢和低合金钢中的一种或多种。
  9. 根据权利要求1所述的抗点焊LME裂纹的高强钢复合镀锌板，其特征是：所述的高强钢主体(1)的原始板坯厚度与低碳钢复合层(2)的原始板坯厚度之间满足关系式：L×A+M×B+N×C＝T；
    其中，A为其中一层低碳钢复合层(2)的原始板坯厚度占总组坯厚度的百分比，C为另一层低碳钢复合层(2)的原始板坯厚度占总组坯厚度的百分比，B为高强钢主体(1)的原始板坯占总组坯厚度的百分比，且A+B+C＝100％；总组坯为高强钢主体(1)和两层低碳钢复合层(2)的原始板坯总厚度；
    L为其中一层低碳钢复合层(2)退火后的抗拉强度，N为另一层低碳钢复合层(2)退火后的抗拉强度，M为高强钢主体(1)退火后的抗拉强度；
    T为高强钢复合镀锌板的目标抗拉强度；
    其中，所述抗拉强度的单位为MPa，所述厚度的单位为微米。
  10. 根据权利要求9所述的抗点焊LME裂纹的高强钢复合镀锌板，其特征是：A∶B、C∶B的数值范围是1∶35.5～1∶5。
  11. 根据权利要求1～10中任一项抗点焊LME裂纹的高强钢复合镀锌板，其特征是：
    所述的高强钢复合镀锌板中，每层低碳钢复合层(2)的厚度均为10-200um；和/或
    所述的高强钢复合镀锌板中，镀锌层(3)的厚度为4-26um。
  12. 根据权利要求1所述的抗点焊LME裂纹的高强钢复合镀锌板，其特征是：所述的高强钢复合镀锌板的抗点焊LME裂纹性能为：在发生焊接飞溅前接头无LME裂纹，在发生焊接飞溅后接头TypeA类LME裂纹长度不超过板厚的10％，且数量不超过6条，TypeD类LME裂纹长度不超过板厚的3％，且数量不超过3条，无TypeB类、TypeC类LME裂纹。
  13. 一种权利要求1～12中任一项所述的抗点焊LME裂纹的高强钢复合镀锌板的制备方法，其特征是：包括以下步骤：
    步骤1：取高强钢主体(1)的原始板坯和两层低碳钢复合层(2)的原始板坯，将两层低碳钢复合层(2)的原始板坯贴合在高强钢主体(1)原始板坯的两个表面上，并将两层低碳钢复合层(2)的原始板坯边缘处与高强钢主体(1)的原始板坯边缘处焊接，形成总组坯；
    步骤2：通过厚板开坯工序将总组坯加热后进行初步轧制，降低总组坯的厚度，再依次进行热轧、酸洗、冷轧、退火，使高强钢主体(1)的原始板坯与两层低碳钢复合层(2)的原始板坯发生冶金结合，形成抗拉强度为T的坯料；
    步骤3：在坯料的至少一个面上镀覆镀锌层(3)，形成高强钢复合镀锌板。
  14. 根据权利要求13所述的制备方法，其特征是：所述的步骤1中，在两层低碳钢复合层(2)的原始板坯与高强钢主体(1)的原始板坯叠放前，需对高强钢主体(1)和两层低碳钢复合层(2)的贴合面进行打磨和清洁。
PCT/CN2023/076709 2022-02-17 2023-02-17 抗点焊lme裂纹的高强钢复合镀锌板及其制备方法 WO2023155868A1 (zh)

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
CN202210145312.6 2022-02-17
CN202210145312.6A CN116657033A (zh) 2022-02-17 2022-02-17 抗点焊lme裂纹的高强钢复合镀锌板及其制备方法

Publications (1)

Publication Number Publication Date
WO2023155868A1 true WO2023155868A1 (zh) 2023-08-24

Family

ID=87577602

Family Applications (1)

Application Number Title Priority Date Filing Date
PCT/CN2023/076709 WO2023155868A1 (zh) 2022-02-17 2023-02-17 抗点焊lme裂纹的高强钢复合镀锌板及其制备方法

Country Status (2)

Country Link
CN (1) CN116657033A (zh)
WO (1) WO2023155868A1 (zh)

Families Citing this family (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN117107148B (zh) * 2023-10-25 2024-02-27 常州市福莱姆车辆配件有限公司 一种高强度复合钢板及其冲压工艺

Citations (9)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JPS61149468A (ja) * 1984-12-25 1986-07-08 Kawasaki Steel Corp 溶融亜鉛めつき仕上げ溶接構造用複合鋼材
JPH04236749A (ja) * 1991-01-16 1992-08-25 Nippon Steel Corp 溶融亜鉛めっき高張力複層鋼板の製造方法
CN1273157A (zh) * 1999-05-07 2000-11-15 宝鸡有色金属加工厂 金属复合板的制造方法
CN102553918A (zh) * 2011-12-22 2012-07-11 江苏天成特种金属复合材料科技有限公司 不锈钢与普碳钢复合带材的轧制方法
CN105296854A (zh) * 2015-09-25 2016-02-03 宝钢不锈钢有限公司 一种具有优良综合性能的冷轧双面不锈钢复合板及制造方法
CN108504956A (zh) * 2017-02-27 2018-09-07 宝山钢铁股份有限公司 高成型性冷轧超高强度复合钢板及其制造方法
US20190040487A1 (en) * 2017-08-04 2019-02-07 GM Global Technology Operations LLC Multilayer steel and method of reducing liquid metal embrittlement
US20190153559A1 (en) * 2016-06-23 2019-05-23 Posco Clad steel plate having excellent strength and formability, and production method therefor
WO2021112480A1 (ko) * 2019-12-06 2021-06-10 주식회사 포스코 용접구조물의 제조방법 및 이에 의해 제조된 용접구조물

Patent Citations (9)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JPS61149468A (ja) * 1984-12-25 1986-07-08 Kawasaki Steel Corp 溶融亜鉛めつき仕上げ溶接構造用複合鋼材
JPH04236749A (ja) * 1991-01-16 1992-08-25 Nippon Steel Corp 溶融亜鉛めっき高張力複層鋼板の製造方法
CN1273157A (zh) * 1999-05-07 2000-11-15 宝鸡有色金属加工厂 金属复合板的制造方法
CN102553918A (zh) * 2011-12-22 2012-07-11 江苏天成特种金属复合材料科技有限公司 不锈钢与普碳钢复合带材的轧制方法
CN105296854A (zh) * 2015-09-25 2016-02-03 宝钢不锈钢有限公司 一种具有优良综合性能的冷轧双面不锈钢复合板及制造方法
US20190153559A1 (en) * 2016-06-23 2019-05-23 Posco Clad steel plate having excellent strength and formability, and production method therefor
CN108504956A (zh) * 2017-02-27 2018-09-07 宝山钢铁股份有限公司 高成型性冷轧超高强度复合钢板及其制造方法
US20190040487A1 (en) * 2017-08-04 2019-02-07 GM Global Technology Operations LLC Multilayer steel and method of reducing liquid metal embrittlement
WO2021112480A1 (ko) * 2019-12-06 2021-06-10 주식회사 포스코 용접구조물의 제조방법 및 이에 의해 제조된 용접구조물

Also Published As

Publication number Publication date
CN116657033A (zh) 2023-08-29

Similar Documents

Publication Publication Date Title
JP7495974B2 (ja) プレス硬化部品を製造するための鋼板、高い強度及び圧潰延性の組合せを有するプレス硬化部品、並びにそれらの製造方法
JP7253837B2 (ja) ホットスタンプ加工済コンポーネントを製造する方法、及びホットスタンプ加工済コンポーネント
US12012655B2 (en) Steel sheet coated with a metallic coating based on aluminum
EP3653738B1 (en) Method for producing a high strength coated steel sheet having improved ductility and formability, and obtained coated steel sheet
RU2430185C2 (ru) Высокопрочная листовая сталь с покрытием, полученным горячим погружением, имеющая высокую ударную вязкость при низких температурах, для использования в штамповке и способ ее производства
EP1227167B1 (en) Hot dip zinc plated steel sheet and method for producing the same
US20050247383A1 (en) High-strength hot-dip galvanized steel sheet with excellent spot weldability and stability of material properties
CN101346480A (zh) 具有出色的可涂镀性和良好的表面性质的高锰钢带、使用该钢带的涂镀钢带及制造所述钢带的方法
CA2786381C (en) High-strength galvanized steel sheet having excellent formability and spot weldability and method for manufacturing the same
CN111356783B (zh) 用于制造抗液态金属脆化的锌涂覆的钢板的方法
US20160194744A1 (en) Method of producing high-strength hot-dip galvanized steel sheet and method of producing high-strength galvannealed steel sheet
JP2006063360A5 (zh)
WO2023155868A1 (zh) 抗点焊lme裂纹的高强钢复合镀锌板及其制备方法
KR101585721B1 (ko) 용접성이 우수한 아연도금강판 및 이의 제조 방법
WO2020212781A1 (en) A method for resistance spot welding of zinc-coated high strength steels
JP2002206139A (ja) めっき密着性およびプレス成形性に優れた高強度合金化溶融亜鉛めっき鋼板と高強度溶融亜鉛めっき鋼板およびその製造方法
KR20160058289A (ko) 가공성 및 점용접성이 우수한 합금화 용융아연도금강판 및 그 제조방법
JP2000109965A (ja) 加工性に優れた溶融亜鉛めっき高張力鋼板の製造方法
JP3048278B2 (ja) 溶接部の疲労特性が優れた高強度熱延原板合金化溶融亜鉛めっき鋼板及びその製造方法
JP7327676B2 (ja) 抵抗スポット溶接部材およびその抵抗スポット溶接方法
WO2024061368A1 (zh) 一种低点焊裂纹敏感性的带镀层超高强钢及其制造方法
US20240246167A1 (en) Automotive member and resistance spot welding method therefor
JP3015841B2 (ja) 溶接部の疲労特性が優れた高強度熱延鋼板及びその製造方法
CN117098866A (zh) 镀锌系钢板及其制造方法
CN116507760A (zh) 热压构件和热压用钢板以及热压构件的制造方法

Legal Events

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

Ref document number: 23755869

Country of ref document: EP

Kind code of ref document: A1