WO2020108594A1 - Zinc-based plated hot-formed steel plate or steel strip having excellent cold bending performance, and manufacturing method thereof - Google Patents

Zinc-based plated hot-formed steel plate or steel strip having excellent cold bending performance, and manufacturing method thereof Download PDF

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Publication number
WO2020108594A1
WO2020108594A1 PCT/CN2019/121860 CN2019121860W WO2020108594A1 WO 2020108594 A1 WO2020108594 A1 WO 2020108594A1 CN 2019121860 W CN2019121860 W CN 2019121860W WO 2020108594 A1 WO2020108594 A1 WO 2020108594A1
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zinc
hot
steel strip
steel
steel sheet
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PCT/CN2019/121860
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French (fr)
Chinese (zh)
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毕文珍
洪继要
王利
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宝山钢铁股份有限公司
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    • C—CHEMISTRY; METALLURGY
    • C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
    • C22C—ALLOYS
    • C22C38/00—Ferrous alloys, e.g. steel alloys
    • C22C38/02—Ferrous alloys, e.g. steel alloys containing silicon
    • 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
    • C21D8/00—Modifying the physical properties by deformation combined with, or followed by, heat treatment
    • C21D8/02—Modifying the physical properties by deformation combined with, or followed by, heat treatment during manufacturing of plates or strips
    • C21D8/0247—Modifying the physical properties by deformation combined with, or followed by, heat treatment during manufacturing of plates or strips characterised by the heat treatment
    • C21D8/0273—Final recrystallisation annealing
    • C—CHEMISTRY; METALLURGY
    • C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
    • C22C—ALLOYS
    • C22C38/00—Ferrous alloys, e.g. steel alloys
    • C22C38/001—Ferrous alloys, e.g. steel alloys containing N
    • 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
    • C22C38/002—Ferrous alloys, e.g. steel alloys containing In, Mg, or other elements not provided for in one single group C22C38/001 - C22C38/60
    • 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
    • C22C38/60—Ferrous alloys, e.g. steel alloys containing lead, selenium, tellurium, or antimony, or more than 0.04% by weight of sulfur
    • 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
    • C23C2/34—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 invention relates to the field of metal materials, in particular to a zinc-plated hot-formed steel sheet or steel strip with excellent cold bending performance and a manufacturing method thereof, which is mainly used for manufacturing structural parts such as automobile B-pillars, door anti-collision beams, and bumpers .
  • hot stamping forming technology is a combination of heat treatment and high temperature forming to achieve high strength of the part, which can better solve the problem of high strength and cold forming Of contradictions.
  • the requirements for the collision performance of the material after hot stamping such as cold bending performance and impact toughness, have also increased accordingly, while traditional hot stamping steel cannot meet the demand.
  • the heating process of traditional unplated hot stamping parts will cause oxidation and peeling on the surface of the stamped steel plate.
  • the oxide scale increases the friction coefficient of the steel plate and the mold and reduces the service life of the mold. At the same time, the oxide scale causes the mold to be cleaned regularly, greatly Reduced production efficiency.
  • the oxide scale generated on the surface needs to be removed by shot blasting. The shot blasting process causes tiny cracks on the surface of the stamped part, which limits production and use.
  • the hot stamped steel sheet has high temperature resistance and corrosion resistance, and a coating technology suitable for hot stamped steel has been developed.
  • hot stamping steel coatings mainly include Al-Si coating, GI coating, GA coating and Zn-Ni coating.
  • the hot stamping steel plate with coating has a good working environment during stamping, and the surface quality of the parts is high. No subsequent shot blasting process is required, which can not only prevent surface oxidation and decarbonization during the molding process, but also improve the anti-corrosion performance after painting.
  • the object of the present invention is to provide a zinc-plated hot-formed steel sheet or steel strip with excellent cold bending performance and a method for manufacturing the same.
  • the tensile strength of the zinc-plated hot-formed steel sheet is greater than 1400 MPa and the elongation after break is greater than 5% , Mainly used in the manufacture of structural parts such as automobile B-pillars, door anti-collision beams, and bumpers.
  • the strength and elongation of hot stamped steel plates do not fully characterize the crash performance of parts, and cold bending performance is an important feature to characterize the crash performance, because extreme plastic deformation occurs in hot stamped parts during collision, which makes hot stamped parts
  • the surface undergoes severe complete deformation, especially cold bending performance is particularly important in materials with tensile strength above 980MPa.
  • the present invention found after relevant research that adding a small amount of Nb element to the conventional hot stamped steel sheet will refine the original austenite grains and the final martensite structure of the steel sheet, and accordingly increase the cold bending of the material performance.
  • the study found that increasing the dew point during the annealing of the steel sheet can produce a certain depth of the decarburized layer on the surface of the galvanized sheet substrate. Due to the high ferrite content in the decarburized layer, it is also beneficial to the cold bending performance of the material.
  • the present invention provides a zinc-plated hot-formed steel sheet or steel strip having excellent cold bending performance.
  • the zinc-plated hot-formed steel sheet or steel strip includes a surface decarburized layer with a thickness of 25 ⁇ m or less, preferably 20 ⁇ m or less.
  • the zinc-based plating layer is a pure zinc plating layer or a zinc-iron alloy plating layer containing 10% to 20% iron.
  • the substrate component further contains at least one of Cr: 0.01 to 1.0%, Mo: 0.01 to 1.0%, Ti ⁇ 0.2%, Nb: 0.01 to 0.08%, V: 0.01 to 1.0%, and B: 0.001 to 0.08% One kind.
  • the substrate component of the present invention contains 0.01-0.08% of Nb, 0.005-0.05% of Ti, and 0.001-0.01% of B.
  • the substrate composition of the present invention further includes 0.1-0.3% Cr and/or 0.01-0.2% Mo.
  • the substrate composition of the present invention is: C: 0.1-0.8%, Si: 0.05-2.0%, Mn: 0.5-3.0%, P ⁇ 0.05%, S ⁇ 0.01%, Al: 0.01-0.1%, Ti: 0.005-0.05%, N ⁇ 0.01%, B: 0.001-0.004%, Nb: 0.02-0.05%, and optionally one or two of Cr of 0.1-0.3% and Mo of 0.01-0.2% , The remainder is Fe and inevitable impurities.
  • Carbon content is the most important factor that determines the mechanical properties of steel plates such as strength and hardness.
  • the strength and hardness of steel increase with increase, the plasticity and toughness decrease, and the tendency to cold brittleness and aging also increase.
  • the carbon content also has a significant effect on the mechanical properties of the steel after quenching, because the hardness of the martensite structure after quenching mainly depends on the carbon content.
  • the C content must be above 0.10%.
  • the toughness of the quenched part deteriorates significantly. Therefore, the C content is set to 0.8% or less, preferably 0.5% or less, such as 0.1 to 0.5%. In some embodiments, the C content is preferably 0.15 to 0.72%.
  • Si is a replacement solid solution alloy element, which can promote the enrichment of C in austenite, increase the stability of austenite, improve the strength of steel, and increase its toughness to a certain extent.
  • the Si content should be less than 2.0%; in some embodiments, the Si content is 0.05% or more. In some embodiments, the Si content is 1.7% or less, such as 0.04% or 0.05% to 1.7%.
  • Mn is an element that improves the hardenability of the steel sheet and stably ensures the strength after quenching.
  • Mn as an element that expands the austenite phase region, can lower the Ac3 and Ac1 point temperatures, delay the pearlite transformation, and thus reduce the hot stamping heating temperature.
  • Mn will diffuse into the plating film during heating before hot forming, forming Mn oxide on the surface of the plating layer, thereby suppressing excessive generation of zinc oxide layer, which is beneficial to spot welding performance after hot forming.
  • the Mn content is less than 0.5%, the effect is insufficient.
  • the Mn content exceeds 3%, segregation occurs, resulting in a decrease in the performance uniformity of the substrate steel plate and hot stamping parts.
  • the Mn content is 0.7-3.0%.
  • the Sol. Al has the effect of deoxidizing steel.
  • the Sol. Al content is set to 0.005% or more.
  • the Sol.Al content exceeds 1.0%, the effects of the above-mentioned effects are saturated, and this is disadvantageous in terms of cost. Therefore, the Sol.Al content is set to 1.0% or less.
  • the Sol. Al content is 0.01 to 0.20%, more preferably 0.01 to 0.07%.
  • Nb is an important microalloying element in steel. Adding a small amount of Nb to the steel can ensure that the steel has a low carbon equivalent through the dispersion and precipitation of its carbon and nitride points (size less than 5nm) and the solid solution of Nb , Refine the grain, greatly improve the strength and toughness of the steel, especially the low temperature toughness, and at the same time make the steel have good cold bending performance and weldability.
  • the Nb content is preferably 0.02 to 0.05%, which can effectively refine the original austenite grains of the steel substrate, and the purpose is to improve the cold bending performance of the part after hot forming.
  • B is an element with strong segregation of grain boundaries in steel, which can reduce the austenite grain boundary energy and inhibit the formation of proeutectoid ferrite nuclei. It has three major characteristics for improving the hardenability of steel: improving hardenability The ability of sex is very strong, some literature pointed out that the effect of 0.001% to 0.003% B can be equivalent to 0.6% Mn, 0.7% Cr, 0.5% Mo and 1.5% Ni, and only a small amount of B can be saved A large number of precious alloy elements; B has the best content to improve the hardenability, which is different from the general alloy elements. The effect of improving the hardenability increases with its content in the steel. B has an optimal content range, the content is very small, Too much or too little is detrimental to improving hardenability. In the present invention, the B content is preferably controlled to 0.001% to 0.004%.
  • the substrate steel sheet may further contain the following optional components in a predetermined range in addition to the above-mentioned essential components.
  • the optional components described below may not be included: Ti: 0 to 0.20%, V: 0 to 1.0%, W: 0 to 1.0%, Cr: 0 to 1.0%, Mo : 0 to 1.0%.
  • the substrate contains 0.005-0.10%, preferably 0.005-0.05% Ti.
  • Cr when Cr is contained, its content may be 0.05 to 0.3%, preferably 0.1 to 0.3%.
  • Mo when Mo is contained, its content may be 0.01 to 0.2%, preferably 0.05 to 0.2%.
  • the substrate steel sheet of the present invention contains 0.005-0.05% of Ti, and contains at least one of Cr and Mo.
  • a Zn-based plating layer having an adhesion amount of 10 g/m 2 or more is provided on the surface of the steel sheet.
  • the adhesion amount of the plating layer (on each side of the steel sheet) is 10 to 100 g/m 2 , and if it is less than 10 g/m 2 , the sacrificial anode corrosion prevention effect of Zn cannot be fully exerted, and if it exceeds 100 g/m 2 , the effect is saturated. And cause costs to rise.
  • the Zn-based plating layer in addition to pure Zn plating (for example, a plating layer formed by hot-dip galvanized wire or electrogalvanized wire), it can also be a Zn-Fe alloy plating layer (plated layer coated with a hot-dip galvanized wire), Zn -Ni alloy coating, Zn-Al alloy coating, Zn-Mg alloy coating, Zn-Al-Mg alloy coating, etc.
  • a Zn-based composite plating layer formed by dispersing a metal oxide, a polymer, or the like in such a Zn-based plating layer may be used, or a plurality of such Zn-based plating layers may be laminated and formed.
  • the weight percentage of zinc in the coating of the present invention may be above 25%, such as 25-40%.
  • the surface layer of the steel sheet of the present invention has an internal oxide layer with a thickness of 1 to 5 ⁇ m.
  • the internal oxide layer contains oxide particles, and the oxide particles are one or more of Si oxide and Si and Mn composite oxides.
  • the characteristic of the inner oxide layer of a certain thickness on the surface layer of the steel plate of the present invention is necessary, and it has an inevitable relationship with the content of Si and Mn in the steel plate and the dew point during the annealing dip plating process. Since the Nb element is added to the steel plate in the present invention, the original austenite grains are effectively refined, and the grain size is 15 ⁇ m or less.
  • the method for manufacturing a zinc-based plated hot-formed steel sheet or steel strip with excellent cold bending performance includes the following steps:
  • Hot rolling The cast billet is heated to 1100 ⁇ 1250°C and then controlled to roll.
  • the open rolling temperature is 950 ⁇ 1150°C
  • the final rolling temperature is 750 ⁇ 900°C
  • the thickness of the hot rolled sheet is less than or equal to 20mm;
  • Annealing and galvanizing The steel coil is heated to 500-850°C within the dew point range of -40-30°C, so that the steel coil has a decarburized layer of less than 25 ⁇ m, such as 5-25 ⁇ m or 10-25 ⁇ m before galvanizing Then, in the range of 1 to 30 volume percent H 2 , it is cooled to 400 to 500 °C at a cooling rate of 10 to 30 °C/s, without holding or holding time within 100 s, and then immersed into the plating solution, plating The liquid temperature is 440-480°C, and finally cooled to room temperature at a cooling rate of ⁇ 30°C/s to obtain a zinc-based plated hot-formed steel plate or steel strip.
  • the plating layer is an alloyed layer
  • reheating is performed with a gas furnace, an induction furnace, etc.
  • the alloying temperature is set to 480°C or higher, preferably 500 to 650°C.
  • the cold rolling reduction in the step 5) is 50-60%.
  • the dew point in step 6 is -10 to 20°C.
  • step 6 it is heated to 650-800°C.
  • the steel coil is heated to 650-800°C, preferably 700-800°C in the range of 0-10°C dew point.
  • the present invention also includes the following hot stamping forming steps:
  • Heating Put the steel plate or steel strip in a continuous annealing furnace, and heat the steel plate or steel strip to a temperature higher than Ac 3 at a heating rate of more than 5°C/s.
  • the holding time is 1 to 10 minutes to make the steel plate Or the austenite of the steel strip is uniform; usually, the steel plate or the steel strip is heated to a temperature not higher than 1000 °C, and then kept warm;
  • Hot stamping and in-mold quenching move the fully austenitized steel plate to the hot stamping die for stamping and quenching, the forming temperature range is less than 780°C, preferably 400 ⁇ 650°C, hot stamping and holding time 3 ⁇ 15 seconds, the punching pressure is 300-1000 tons; after the hot stamping is completed, the steel plate or steel strip is cooled to room temperature in the mold, or taken out of the mold and then cooled to room temperature to complete the martensite transformation.
  • the steel sheet or steel strip is pre-cooled before stamping, and the pre-cooling speed is greater than 30°C/s, such as 30-60°C/s.
  • the pre-cooling is carried out by air mist or water mist cooling.
  • the steel plate or steel strip is cooled in the mold to a room temperature at a cooling rate greater than 30°C/s.
  • the substrate smelting may use a converter or an electric furnace or an induction furnace.
  • the plating layer is an alloyed layer, after hot dip galvanizing, reheat it with a gas furnace or induction heating furnace, etc., metal diffusion between the plating layer and the substrate steel plate, and the plating film is alloyed (If forming a Zn-Fe alloy).
  • the alloying temperature is set to 480°C or higher. When the temperature is less than 480°C, the alloying rate is slow, so the production efficiency is reduced. The higher the alloying temperature, the faster the alloying rate. Above Ac 1 point, the strength of the steel sheet will be reduced. Therefore, the preferred range of alloying temperature is 500 to 650 °C.
  • the molten zinc must avoid contact with austenite as much as possible during the forming stage, therefore, hot stamping must be performed at a temperature lower than the melting point of the coating after hot stamping.
  • the boron element can be added to delay the transformation of austenite to martensite and improve the hardenability of the steel plate or steel strip.
  • ⁇ Ac 3 austenite transformation end temperature
  • Hot stamping and in-mold quenching The blanked steel plate or steel strip is quickly moved to the hot stamping die for stamping and quenching.
  • the forming temperature range is less than 780°C, such as 570 ⁇ 780°C, preferably 400 ⁇ 650 °C, pre-cooling can be added before stamping.
  • the hot stamping forming pressure holding time is about 3 to 15 seconds, and the punching pressure is 300 to 1,000 tons.
  • the steel plate or steel strip is cooled in the mold, or taken out of the mold and then cooled to room temperature to complete the martensite transformation.
  • the method of the present invention can make the conventional coated hot stamping steel 22MnB5 contain a decarburized layer before and after hot stamping, and its original austenite grains are more refined than the traditional hot stamped steel sheet (FIG. 3 And Figure 4), therefore, the cold bending performance of the hot stamping part in the present invention is greatly improved (Figure 5).
  • the hot stamping process described in the present invention can also avoid matrix cracks caused by liquid metal brittleness (Liquid Metal Embrittlement, hereinafter referred to as LME) after stamping of hot stamping steel sheets with zinc-based coatings. Significance.
  • LME liquid metal brittleness
  • the beneficial effects of the present invention are of great significance to the development of hot stamping steel.
  • the cold bending angle of the zinc-plated hot-formed steel sheet or steel strip of the present invention measured by the VDA238-100 standard test method is ⁇ 50 degrees, preferably ⁇ 55 degrees, more preferably ⁇ 60 degrees.
  • Fig. 1 is a cross-sectional metallography of a hot-formed steel plate of Example 3 of the present invention (after hot forming);
  • Figure 2 is the metallography of the oxide layer in the section of the hot-formed steel plate of the present invention (before hot-forming);
  • Example 3 is a picture of the original austenite grains of the hot-formed steel plate of Example 3 of the present invention.
  • FIG. 5 is a comparison diagram of cold bending angles of the steel plate of Example 5 of the present invention and the comparative steel plate after hot forming.
  • Steel plates 1 to 6 having chemical compositions shown in Table 1 were melted and cast. These steel sheets were heated to 1230°C to control rolling, the final rolling temperature was 900°C, and then a hot-rolled steel sheet with a thickness of about 3 mm was obtained at a coiling temperature of 600°C. The hot-rolled steel sheet was pickled and cold-rolled to a thickness of 1.4 mm. hard Board.
  • the above-mentioned hard-rolled plates are recrystallized and annealed and hot-dip galvanized to obtain galvanized steel plates. After these plates are kept at 930°C for 4 minutes, they are sent to the mold according to the forming process in Table 3 to form B-pillar parts.
  • the crystal grain size in the original austenite grains (FIG. 4) is significantly larger than that in the example 3 (FIG. 3 ).
  • the thickness of the decarburized layer of the substrate is 0 ⁇ m, according to the VDA238-100 standard The method was used to determine the angle of cold bending, as shown in FIG. 5. As a result, it can be seen that its cold bending performance is significantly inferior to the examples.
  • the steel plate and hot stamping process produced according to the method of the present invention have good serviceability.
  • the zinc-based plated hot-formed steel sheet or steel strip produced according to the method of the present invention has a tensile strength greater than 1400 MPa and an elongation after fracture greater than 5% according to JIS13B testing.

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  • Engineering & Computer Science (AREA)
  • Materials Engineering (AREA)
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  • Metallurgy (AREA)
  • Organic Chemistry (AREA)
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Abstract

Provided are a zinc-based plated hot-formed steel plate or steel strip having excellent cold bending performance, and a manufacturing method thereof; said zinc-based plated hot-formed steel plate or steel strip comprises a substrate having a surface decarburized layer thickness of less than 20 um and a zinc-based plated layer having an adhesion amount of 10 to 100 g/m^2; the component weight percentages of the substrate are: C: 0.1–0.8%, Si: 0.05–2.0%, Mn: 0.5–3.0%, P≤0.1%, S≤0.05%, Al≤0.1%, N≤0.01%; the remainder is Fe and unavoidable impurities; the average size of original austenite grains of the substrate is less than 15 um. After hot forming of the substrate, the hot-formed steel plate or steel strip has a tensile strength of 1500 MPa and elongation after fracture of 5%, and the coating is continuous and complete, there are no cracks extending to the substrate, and the steel plate has excellent cold bending performance.

Description

一种冷弯性能优良的锌系镀覆热成型钢板或钢带及其制造方法Zinc-based plated hot-formed steel sheet or steel strip with excellent cold bending performance and manufacturing method thereof 技术领域Technical field
本发明涉及金属材料领域，特别涉及一种冷弯性能优良的锌系镀覆热成型钢板或钢带及其制造方法，主要应用于制造汽车B柱、车门防撞梁、保险杠等结构件部件。The invention relates to the field of metal materials, in particular to a zinc-plated hot-formed steel sheet or steel strip with excellent cold bending performance and a manufacturing method thereof, which is mainly used for manufacturing structural parts such as automobile B-pillars, door anti-collision beams, and bumpers .
背景技术Background technique
汽车轻量、安全、低能耗的发展趋势促进了高强度钢板的发展。采用先进超高强钢替代传统的低强度钢板成为必然，高强度钢板的采用还可以显著提高汽车的碰撞安全性。但随着钢板强度的提高，零件加工的难度也不断增加。对冲压成形工艺而言，减薄和高强是恶化成形性的双重因素，不仅使得车身零件在成形过程中容易开裂，而且容易产生过量回弹，影响车身后续的装配。通过热处理的方式实现最终零件的高强度是其中的一种途径，而热冲压成形技术是一种通过热处理和高温成形相结合的方式来实现零件高强度，能较好的解决高强度与冷成形的矛盾问题。但随着热冲压钢的大量应用，随之而来对材料热冲压后零件的碰撞性能，如冷弯性能和冲击韧性的要求也相应提高，而传统的热冲压钢不能满足需求。The development trend of automobile light weight, safety and low energy consumption has promoted the development of high-strength steel plates. The use of advanced ultra-high-strength steel to replace traditional low-strength steel plates is inevitable. The use of high-strength steel plates can also significantly improve the crash safety of automobiles. However, as the strength of the steel plate increases, the difficulty of processing parts continues to increase. For the stamping forming process, thinning and high strength are the two factors that deteriorate the formability, which not only makes the body parts easy to crack during the forming process, but also easily generates excessive springback, which affects the subsequent assembly of the body. One way is to achieve high strength of the final part through heat treatment, and hot stamping forming technology is a combination of heat treatment and high temperature forming to achieve high strength of the part, which can better solve the problem of high strength and cold forming Of contradictions. However, with the large number of applications of hot stamping steel, the requirements for the collision performance of the material after hot stamping, such as cold bending performance and impact toughness, have also increased accordingly, while traditional hot stamping steel cannot meet the demand.
另外，传统的无镀层热冲压件加热过程中会引起冲压钢板表面氧化起皮，氧化皮则增大了钢板与模具的摩擦系数、降低模具的使用寿命，同时氧化皮导致需要定时清理模具，大大降低了生产效率。为满足冲压件的后续处理要求，需要通过喷丸去除表面生成的氧化皮，喷丸工序使得冲压件表面产生微小裂纹，限制了生产使用。为避免热冲压钢板表面的氧化和脱碳使热冲压钢板具备耐高温性和耐腐蚀性，目前已开发出适合于热冲压钢用镀层技术。目前热冲压钢镀层主要有Al-Si镀层、GI镀层、GA镀层和Zn-Ni镀层等。带镀层的热冲压钢板，冲压时工作环境好，零件表面质量高，后续无需喷丸工序，不仅可以防止成型过程中表面氧化和脱碳，还能提高漆装后的防腐蚀性能。In addition, the heating process of traditional unplated hot stamping parts will cause oxidation and peeling on the surface of the stamped steel plate. The oxide scale increases the friction coefficient of the steel plate and the mold and reduces the service life of the mold. At the same time, the oxide scale causes the mold to be cleaned regularly, greatly Reduced production efficiency. In order to meet the subsequent processing requirements of stamping parts, the oxide scale generated on the surface needs to be removed by shot blasting. The shot blasting process causes tiny cracks on the surface of the stamped part, which limits production and use. In order to avoid oxidation and decarburization of the surface of the hot stamped steel sheet, the hot stamped steel sheet has high temperature resistance and corrosion resistance, and a coating technology suitable for hot stamped steel has been developed. At present, hot stamping steel coatings mainly include Al-Si coating, GI coating, GA coating and Zn-Ni coating. The hot stamping steel plate with coating has a good working environment during stamping, and the surface quality of the parts is high. No subsequent shot blasting process is required, which can not only prevent surface oxidation and decarbonization during the molding process, but also improve the anti-corrosion performance after painting.
发明内容Summary of the invention
本发明的目的在于提供一种冷弯性能优良的锌系镀覆热成型钢板或钢带及其制造方法，所述锌系镀覆热成型钢板的抗拉强度大于1400MPa，断后延伸率大于5％，主要应用于制造汽车B柱、车门防撞梁、保险杠等结构件部件。The object of the present invention is to provide a zinc-plated hot-formed steel sheet or steel strip with excellent cold bending performance and a method for manufacturing the same. The tensile strength of the zinc-plated hot-formed steel sheet is greater than 1400 MPa and the elongation after break is greater than 5% , Mainly used in the manufacture of structural parts such as automobile B-pillars, door anti-collision beams, and bumpers.
为达到上述目的，本发明的技术方案是：To achieve the above objectives, the technical solutions of the present invention are:
热冲压钢板的强度和延伸率并不能完全表征零件的碰撞性能，而冷弯性能则是表征碰撞性能的重要特征，因为在碰撞时热冲压零件中产生极端的塑性变形，从而使热冲压零件的表面经受严重的完全变形，特别是在抗拉强度980MPa以上的材料中冷弯性能尤其重要。本发明在相关的研究后发现，在常规的热冲压钢板中添加少量的Nb元素，会对钢板的原始奥氏体晶粒和最终的马氏体组织进行细化，相应地提高材料的冷弯性能。同时，研究发现在钢板退火时提高露点，可在镀锌板基板表面产生一定深度的脱碳层，由于脱碳层内铁素体含量高，同样对材料的冷弯性能有益。The strength and elongation of hot stamped steel plates do not fully characterize the crash performance of parts, and cold bending performance is an important feature to characterize the crash performance, because extreme plastic deformation occurs in hot stamped parts during collision, which makes hot stamped parts The surface undergoes severe complete deformation, especially cold bending performance is particularly important in materials with tensile strength above 980MPa. The present invention found after relevant research that adding a small amount of Nb element to the conventional hot stamped steel sheet will refine the original austenite grains and the final martensite structure of the steel sheet, and accordingly increase the cold bending of the material performance. At the same time, the study found that increasing the dew point during the annealing of the steel sheet can produce a certain depth of the decarburized layer on the surface of the galvanized sheet substrate. Due to the high ferrite content in the decarburized layer, it is also beneficial to the cold bending performance of the material.
具体的，本发明提供一种冷弯性能优良的锌系镀覆热成型钢板或钢带，所述锌系镀覆热成型钢板或钢带包括表面脱碳层厚度在25μm以下、优选20μm以下的基板及其上附着量为10～100g/m 2的锌系镀层；所述基板含有：C：0.1～0.8％、Si：0.05～2.0％、Mn：0.5～3.0％、P≤0.1％、S≤0.05％、Al≤0.1％、N≤0.01％，余下为Fe和不可避免的杂质；所述基板的原始奥氏体晶粒平均尺寸在15μm以下。 Specifically, the present invention provides a zinc-plated hot-formed steel sheet or steel strip having excellent cold bending performance. The zinc-plated hot-formed steel sheet or steel strip includes a surface decarburized layer with a thickness of 25 μm or less, preferably 20 μm or less. Substrate and zinc-based plating layer with an adhesion amount of 10 to 100 g/m 2 ; the substrate contains: C: 0.1 to 0.8%, Si: 0.05 to 2.0%, Mn: 0.5 to 3.0%, P≤0.1%, S ≤0.05%, Al≤0.1%, N≤0.01%, the balance is Fe and inevitable impurities; the average size of the original austenite grains of the substrate is below 15 μm.
优选的，所述锌系镀层为纯锌镀层或者含有10％～20％铁的锌铁合金镀层。Preferably, the zinc-based plating layer is a pure zinc plating layer or a zinc-iron alloy plating layer containing 10% to 20% iron.
优选的，所述基板成分还含有Cr：0.01～1.0％、Mo：0.01～1.0％、Ti≤0.2％、Nb：0.01～0.08％、V：0.01～1.0％、B：0.001～0.08％中至少一种。Preferably, the substrate component further contains at least one of Cr: 0.01 to 1.0%, Mo: 0.01 to 1.0%, Ti ≤ 0.2%, Nb: 0.01 to 0.08%, V: 0.01 to 1.0%, and B: 0.001 to 0.08% One kind.
优选的，本发明所述基板成分中含有0.01-0.08％的Nb、0.005-0.05％的Ti和0.001-0.01％的B。任选地，本发明所述基板成分中还包括0.1-0.3％的Cr和/或0.01-0.2％的Mo。Preferably, the substrate component of the present invention contains 0.01-0.08% of Nb, 0.005-0.05% of Ti, and 0.001-0.01% of B. Optionally, the substrate composition of the present invention further includes 0.1-0.3% Cr and/or 0.01-0.2% Mo.
在一些实施方案中，本发明基板成分为：C：0.1～0.8％、Si：0.05～2.0％、Mn：0.5～3.0％、P≤0.05％、S≤0.01％、Al：0.01-0.1％、Ti：0.005-0.05％、N≤0.01％、B：0.001-0.004％、Nb：0.02-0.05％，以及任选的0.1-0.3％的Cr和0.01-0.2％的Mo中的一种或两种，余下为Fe和不可避免的杂质。In some embodiments, the substrate composition of the present invention is: C: 0.1-0.8%, Si: 0.05-2.0%, Mn: 0.5-3.0%, P≤0.05%, S≤0.01%, Al: 0.01-0.1%, Ti: 0.005-0.05%, N≤0.01%, B: 0.001-0.004%, Nb: 0.02-0.05%, and optionally one or two of Cr of 0.1-0.3% and Mo of 0.01-0.2% , The remainder is Fe and inevitable impurities.
在本发明钢的成分设计中：In the composition design of the steel of the present invention:
1，基板的化学组成1. The chemical composition of the substrate
C：0.10～0.8％C: 0.10～0.8%
碳含量是决定钢板强度、硬度等力学性能的最主要因素，钢的强度、硬度随之升高而提高，塑性、韧性随之降低，冷脆倾向性和时效倾向性也随之提高。碳含量还对钢材淬火后力学性能有显著影响，原因在于淬火后马氏体组织的硬度大小主要取决于其中的含碳量高低。要使热冲压零件的抗拉强度在1000MPa以上，必须使C含量在0.10％以上。另一方面，C含量超过0.8％时，淬火部件的韧性劣化显著。因此C含量设为0.8％以下，优选为0.5％以下，如0.1～0.5％。在一些实施方案中，C含量优选为0.15～0.72％。Carbon content is the most important factor that determines the mechanical properties of steel plates such as strength and hardness. The strength and hardness of steel increase with increase, the plasticity and toughness decrease, and the tendency to cold brittleness and aging also increase. The carbon content also has a significant effect on the mechanical properties of the steel after quenching, because the hardness of the martensite structure after quenching mainly depends on the carbon content. To make the tensile strength of hot stamping parts above 1000MPa, the C content must be above 0.10%. On the other hand, when the C content exceeds 0.8%, the toughness of the quenched part deteriorates significantly. Therefore, the C content is set to 0.8% or less, preferably 0.5% or less, such as 0.1 to 0.5%. In some embodiments, the C content is preferably 0.15 to 0.72%.
Si：0.04～2.0％Si: 0.04～2.0%
Si是置换固溶合金元素，它可以促进C在奥氏体中的富集，使得奥氏体稳定性增加，提高钢的强度，并在一定程度上提高其韧性。但是，Si含量超过2.0％时，热轧时产生红色氧化铁皮的表面缺陷的概率增大，且轧制力增大，导致热轧钢板的延展性劣化。因此，Si的含量应小于2.0％；在一些实施方案中，Si含量在0.05％或以上。在一些实施方案中，Si含量为1.7％或以下，如0.04％或0.05％到1.7％。Si is a replacement solid solution alloy element, which can promote the enrichment of C in austenite, increase the stability of austenite, improve the strength of steel, and increase its toughness to a certain extent. However, when the Si content exceeds 2.0%, the probability of occurrence of surface defects of red scale during hot rolling increases, and the rolling force increases, resulting in deterioration of the ductility of the hot-rolled steel sheet. Therefore, the Si content should be less than 2.0%; in some embodiments, the Si content is 0.05% or more. In some embodiments, the Si content is 1.7% or less, such as 0.04% or 0.05% to 1.7%.
Mn：0.5～3.0％Mn: 0.5～3.0%
Mn是提高钢板的淬透性、并且稳定地确保淬火后强度非常有效的元素。同时Mn作为扩大奥氏体相区的元素，可以降低Ac3和Ac1点温度，延缓珠光体相变，从而降低热冲压加热温度。此外，在热成形前加热过程中Mn会扩散到镀覆覆膜中，在镀层表面形成Mn的氧化物，从而抑制锌氧化层过度地产生，对热成形后点焊性能有利。Mn含量不足0.5％时，效果不充分。另一方面，Mn含量超过3％时，会产生偏析，导致基板钢板和热冲压零件性能均匀性下降。优选地，Mn含量为0.7～3.0％。Mn is an element that improves the hardenability of the steel sheet and stably ensures the strength after quenching. At the same time, Mn, as an element that expands the austenite phase region, can lower the Ac3 and Ac1 point temperatures, delay the pearlite transformation, and thus reduce the hot stamping heating temperature. In addition, Mn will diffuse into the plating film during heating before hot forming, forming Mn oxide on the surface of the plating layer, thereby suppressing excessive generation of zinc oxide layer, which is beneficial to spot welding performance after hot forming. When the Mn content is less than 0.5%, the effect is insufficient. On the other hand, when the Mn content exceeds 3%, segregation occurs, resulting in a decrease in the performance uniformity of the substrate steel plate and hot stamping parts. Preferably, the Mn content is 0.7-3.0%.
Al：0.005～1.0％Al: 0.005～1.0%
Al具有将钢脱氧的作用。Sol.Al含量不足0.005％时，难以得到基于上述作用的效果，因此，Sol.Al含量设定为0.005％以上。另一方面，Sol.Al含量超过1.0％时，上述作用的效果饱和，且在成本上不利。因此，Sol.Al含量设定为1.0％以下。优选地，Sol.Al含量为0.01～0.20％，更优选为0.01～0.07％。Al has the effect of deoxidizing steel. When the Sol. Al content is less than 0.005%, it is difficult to obtain the effects based on the above-mentioned effects, so the Sol. Al content is set to 0.005% or more. On the other hand, when the Sol.Al content exceeds 1.0%, the effects of the above-mentioned effects are saturated, and this is disadvantageous in terms of cost. Therefore, the Sol.Al content is set to 1.0% or less. Preferably, the Sol. Al content is 0.01 to 0.20%, more preferably 0.01 to 0.07%.
N：0.01％以下N: 0.01% or less
N含量超过0.01％时，在热轧时会形成AlN的氮化物，导致基板钢板的冲裁加 工性能和淬透性降低。When the N content exceeds 0.01%, AlN nitride is formed during hot rolling, resulting in a decrease in the blanking workability and hardenability of the substrate steel sheet.
Nb：0.01～0.08％Nb: 0.01～0.08%
Nb是钢中重要的微合金元素，在钢中添加微量的Nb可保证钢在碳当量较低的情况下，通过其碳、氮化物质点(尺寸小于5nm)的弥散析出及Nb的固溶，细化晶粒，极大地提高钢的强度、韧性，特别是低温韧性，同时使钢具有良好的冷弯性能和可焊性。本发明中优选Nb含量在0.02～0.05％，可有效细化钢基板的原始奥氏体晶粒，目的在于提高热成形后零件的冷弯性能。Nb is an important microalloying element in steel. Adding a small amount of Nb to the steel can ensure that the steel has a low carbon equivalent through the dispersion and precipitation of its carbon and nitride points (size less than 5nm) and the solid solution of Nb , Refine the grain, greatly improve the strength and toughness of the steel, especially the low temperature toughness, and at the same time make the steel have good cold bending performance and weldability. In the present invention, the Nb content is preferably 0.02 to 0.05%, which can effectively refine the original austenite grains of the steel substrate, and the purpose is to improve the cold bending performance of the part after hot forming.
B：0.005～0.08％B: 0.005～0.08%
B是钢中晶界偏聚强烈的元素，能降低奥氏体的晶界能，抑制先共析铁素体晶核的形成，对于提高钢的淬透性作用具有三大特点：提高淬透性的能力很强，有文献指出0.001％～0.003％的B作用可分别相当于0.6％的Mn、0.7％的Cr、0.5％的Mo和1.5％的Ni，只需极少量的B即可节约大量的贵重合金元素；B有提高淬透性的最佳含量，不同于一般合金元素提高淬透性的效果随其在钢中含量增加而增加，B有一个最佳含量范围，含量十分微小，过多或过少均对提高淬透性不利。本发明中优选B含量控制在0.001％～0.004％。B is an element with strong segregation of grain boundaries in steel, which can reduce the austenite grain boundary energy and inhibit the formation of proeutectoid ferrite nuclei. It has three major characteristics for improving the hardenability of steel: improving hardenability The ability of sex is very strong, some literature pointed out that the effect of 0.001% to 0.003% B can be equivalent to 0.6% Mn, 0.7% Cr, 0.5% Mo and 1.5% Ni, and only a small amount of B can be saved A large number of precious alloy elements; B has the best content to improve the hardenability, which is different from the general alloy elements. The effect of improving the hardenability increases with its content in the steel. B has an optimal content range, the content is very small, Too much or too little is detrimental to improving hardenability. In the present invention, the B content is preferably controlled to 0.001% to 0.004%.
在本发明中，在基板钢板中，在上述的必要成分的基础上，可以进一步在规定范围含有以下的任选成分。需要说明的是，与必要成分不同，也可以不含有以下说明的任选成分：Ti：0～0.20％、V：0～1.0％、W：0～1.0％、Cr：0～1.0％、Mo：0～1.0％。优选地，基板含有0.005～0.10％、优选0.005～0.05％的Ti。优选地，当含有Cr时，其含量可为0.05～0.3％，优选0.1～0.3％。优选地，当含有Mo时，其含量可为0.01～0.2％，优选0.05～0.2％。在一些实施方案中，本发明的基板钢板中含有0.005～0.05％的Ti，并含有Cr和Mo中的至少一种。In the present invention, the substrate steel sheet may further contain the following optional components in a predetermined range in addition to the above-mentioned essential components. In addition, unlike the essential components, the optional components described below may not be included: Ti: 0 to 0.20%, V: 0 to 1.0%, W: 0 to 1.0%, Cr: 0 to 1.0%, Mo : 0 to 1.0%. Preferably, the substrate contains 0.005-0.10%, preferably 0.005-0.05% Ti. Preferably, when Cr is contained, its content may be 0.05 to 0.3%, preferably 0.1 to 0.3%. Preferably, when Mo is contained, its content may be 0.01 to 0.2%, preferably 0.05 to 0.2%. In some embodiments, the substrate steel sheet of the present invention contains 0.005-0.05% of Ti, and contains at least one of Cr and Mo.
2，Zn系镀层2. Zn coating
在本发明中，为了在热成形前的加热时抑制氧化皮的产生，在钢板表面设置附着量为10g/m 2以上的Zn系镀层。这里，镀层的附着量(钢板的每个单面)为10～100g/m 2，小于10g/m 2时，无法充分发挥Zn的牺牲阳极防腐蚀效果，超过100g/m 2，该效果饱和，且导致成本上升。 In the present invention, in order to suppress the generation of scale during heating before hot forming, a Zn-based plating layer having an adhesion amount of 10 g/m 2 or more is provided on the surface of the steel sheet. Here, the adhesion amount of the plating layer (on each side of the steel sheet) is 10 to 100 g/m 2 , and if it is less than 10 g/m 2 , the sacrificial anode corrosion prevention effect of Zn cannot be fully exerted, and if it exceeds 100 g/m 2 , the effect is saturated. And cause costs to rise.
作为Zn系镀层，除纯Zn镀层(例如用热镀锌线、电镀锌线形成的镀层)外，还可以是Zn-Fe合金镀层(用热镀锌线实施过合金化处理的镀层)，Zn-Ni合金镀 层，Zn-Al合金镀层，Zn-Mg合金镀层，Zn-Al-Mg合金镀层等。此外，还可以使用金属氧化物、聚合物等分散在这种Zn系镀层中形成的Zn系复合镀层，也可以是将这种Zn系镀层多个层叠形成的镀层。As the Zn-based plating layer, in addition to pure Zn plating (for example, a plating layer formed by hot-dip galvanized wire or electrogalvanized wire), it can also be a Zn-Fe alloy plating layer (plated layer coated with a hot-dip galvanized wire), Zn -Ni alloy coating, Zn-Al alloy coating, Zn-Mg alloy coating, Zn-Al-Mg alloy coating, etc. In addition, a Zn-based composite plating layer formed by dispersing a metal oxide, a polymer, or the like in such a Zn-based plating layer may be used, or a plurality of such Zn-based plating layers may be laminated and formed.
在一些实施方案中，本发明镀层中锌的重量百分比含量可在25％以上，如25-40％。In some embodiments, the weight percentage of zinc in the coating of the present invention may be above 25%, such as 25-40%.
3，基板钢板的组织3. The structure of the substrate steel plate
本发明的钢板表层存在厚度在1～5μm的内氧化层，该内氧化层含有氧化物颗粒，所述氧化物颗粒为Si氧化物以及Si、Mn复合氧化物之中的一种或多种，本发明钢板表层一定厚度的内氧化层特征是必需的，其与钢板中的Si、Mn含量以及退火浸镀过程中的露点有着必然的联系。本发明中的钢板中由于添加了Nb元素，有效细化了原始奥氏体晶粒，其晶粒尺寸在15μm以下。The surface layer of the steel sheet of the present invention has an internal oxide layer with a thickness of 1 to 5 μm. The internal oxide layer contains oxide particles, and the oxide particles are one or more of Si oxide and Si and Mn composite oxides. The characteristic of the inner oxide layer of a certain thickness on the surface layer of the steel plate of the present invention is necessary, and it has an inevitable relationship with the content of Si and Mn in the steel plate and the dew point during the annealing dip plating process. Since the Nb element is added to the steel plate in the present invention, the original austenite grains are effectively refined, and the grain size is 15 μm or less.
本发明所述的冷弯性能优良的锌系镀覆热成型钢板或钢带的制造方法，其包括如下步骤：The method for manufacturing a zinc-based plated hot-formed steel sheet or steel strip with excellent cold bending performance according to the present invention includes the following steps:
1)按上述的成分冶炼、连铸生产铸坯；1) Smelting and continuous casting of slabs according to the above components;
2)热轧：将铸坯加热到1100～1250℃后控制轧制，开轧温度为950～1150℃，终轧温度为750～900℃，热轧板厚度小于等于20mm；2) Hot rolling: The cast billet is heated to 1100～1250℃ and then controlled to roll. The open rolling temperature is 950～1150℃, the final rolling temperature is 750～900℃, and the thickness of the hot rolled sheet is less than or equal to 20mm;
3)轧后在500～850℃进行卷取，冷却至室温后组织为铁素体和珠光体组织；3) After rolling, coiling is carried out at 500～850℃, and the structure is ferrite and pearlite after cooling to room temperature;
4)酸洗以去除热轧过程中产生的氧化铁皮；4) Pickling to remove the scale produced during hot rolling;
5)冷轧：将钢卷冷轧至2.0mm以下的厚度，冷轧压下量≥35％；5) Cold rolling: Cold rolling the steel coil to a thickness below 2.0 mm, the cold rolling reduction ≥ 35%;
6)退火和镀锌：将钢卷在-40～30℃的露点范围内加热到500-850℃，使钢卷在镀锌前具有25μm以下、如5～25μm或10～25μm的脱碳层，然后在1～30体积百分数％的H 2范围内，以10～30℃/s的冷却速度冷却至400～500℃，不保温或保温时间在100s以内，随后浸镀到镀液中，镀液温度为440～480℃，最后以≥30℃/s冷却速度冷却至室温，得到锌系镀覆热成型钢板或钢带。 6) Annealing and galvanizing: The steel coil is heated to 500-850°C within the dew point range of -40-30°C, so that the steel coil has a decarburized layer of less than 25 μm, such as 5-25 μm or 10-25 μm before galvanizing Then, in the range of 1 to 30 volume percent H 2 , it is cooled to 400 to 500 ℃ at a cooling rate of 10 to 30 ℃/s, without holding or holding time within 100 s, and then immersed into the plating solution, plating The liquid temperature is 440-480°C, and finally cooled to room temperature at a cooling rate of ≥30°C/s to obtain a zinc-based plated hot-formed steel plate or steel strip.
优选的，若镀层为合金化镀层，则在热浸镀锌处理后，用气炉、感应加热炉等进行再加热来进行，合金化温度设定为480℃以上，优选为500～650℃。Preferably, if the plating layer is an alloyed layer, after hot dip galvanizing treatment, reheating is performed with a gas furnace, an induction furnace, etc., and the alloying temperature is set to 480°C or higher, preferably 500 to 650°C.
优选的，所述步骤5)中所述的冷轧压下量为50～60％。Preferably, the cold rolling reduction in the step 5) is 50-60%.
优选的，所述步骤6)中的露点为-10～20℃。Preferably, the dew point in step 6) is -10 to 20°C.
优选的，所述步骤6)中，加热到650-800℃。Preferably, in step 6), it is heated to 650-800°C.
优选的，所述步骤6)中，钢卷在0～10℃的露点范围内加热到650-800℃，优选700-800℃。Preferably, in the step 6), the steel coil is heated to 650-800°C, preferably 700-800°C in the range of 0-10°C dew point.
进一步，本发明还包括如下热冲压成型步骤：Further, the present invention also includes the following hot stamping forming steps:
1)加热：将钢板或钢带放入连续退火的加热炉中，以大于5℃/s的加热速度将钢板或钢带加热到高于Ac 3的温度，保温时间1～10分钟，使钢板或钢带奥氏体化均匀；通常，将钢板或钢带加到到不高于1000℃的温度，然后保温； 1) Heating: Put the steel plate or steel strip in a continuous annealing furnace, and heat the steel plate or steel strip to a temperature higher than Ac 3 at a heating rate of more than 5°C/s. The holding time is 1 to 10 minutes to make the steel plate Or the austenite of the steel strip is uniform; usually, the steel plate or the steel strip is heated to a temperature not higher than 1000 ℃, and then kept warm;
2)热冲压成型与模内淬火：将完全奥氏体化的钢板移动到热冲压模具上冲压成型淬火，成型温度范围为低于780℃，优选400～650℃，热冲压成型保压时间3～15秒，冲压力为300～1000吨；热冲压成型完成后，钢板或钢带在模具中冷却至室温，或从模具取出后冷却至室温，完成马氏体相变。2) Hot stamping and in-mold quenching: move the fully austenitized steel plate to the hot stamping die for stamping and quenching, the forming temperature range is less than 780℃, preferably 400～650℃, hot stamping and holding time 3 ~ 15 seconds, the punching pressure is 300-1000 tons; after the hot stamping is completed, the steel plate or steel strip is cooled to room temperature in the mold, or taken out of the mold and then cooled to room temperature to complete the martensite transformation.
优选的，热冲压成型步骤中，冲压成型前预冷钢板或钢带，预冷却速度大于30℃/s，如30～60℃/s。优选的，采用气雾或水雾冷却方式进行预冷却。Preferably, in the hot stamping step, the steel sheet or steel strip is pre-cooled before stamping, and the pre-cooling speed is greater than 30°C/s, such as 30-60°C/s. Preferably, the pre-cooling is carried out by air mist or water mist cooling.
优选的，热冲压成型步骤中所述的步骤2)中钢板或钢带在模具中冷却以大于30℃/s的冷却速度冷却至室温。Preferably, in the step 2) described in the hot stamping step, the steel plate or steel strip is cooled in the mold to a room temperature at a cooling rate greater than 30°C/s.
在本发明热成型钢板或钢带的制造方法中，所述基板冶炼采用转炉也可以采用电炉或感应炉。In the manufacturing method of the hot-formed steel plate or steel strip of the present invention, the substrate smelting may use a converter or an electric furnace or an induction furnace.
若镀层为合金化镀层，则在热浸镀锌处理后，用气炉或感应加热炉等进行再加热来进行，在镀覆层与基板钢板之间进行金属扩散，镀覆覆膜进行合金化(如形成Zn-Fe合金)。为了提高镀覆层中的Fe含量(％)，将合金化温度设定为480℃以上。不足480℃时，合金化速度慢，因此生产效率降低，合金化温度越高，合金化速度越快，在Ac 1点以上时，会使钢板强度降低，因此合金化温度优选范围为500～650℃。 If the plating layer is an alloyed layer, after hot dip galvanizing, reheat it with a gas furnace or induction heating furnace, etc., metal diffusion between the plating layer and the substrate steel plate, and the plating film is alloyed (If forming a Zn-Fe alloy). In order to increase the Fe content (%) in the plating layer, the alloying temperature is set to 480°C or higher. When the temperature is less than 480°C, the alloying rate is slow, so the production efficiency is reduced. The higher the alloying temperature, the faster the alloying rate. Above Ac 1 point, the strength of the steel sheet will be reduced. Therefore, the preferred range of alloying temperature is 500 to 650 ℃.
在热冲压零部件的热冲压成型步骤中：In the hot stamping step of hot stamping parts:
基于本发明的研究发现，在成型阶段必须尽可能避免熔化的锌与奥氏体接触，因此，必须在低于热冲压后镀层熔点的温度进行热冲压成型。为了在上述情况下仍保证钢板能淬火硬化，可通过添加硼元素，延迟奥氏体向马氏体转化，提高钢板或钢带的淬透性。本发明的热冲压成型工艺具体过程如下：Based on the research of the present invention, it has been found that the molten zinc must avoid contact with austenite as much as possible during the forming stage, therefore, hot stamping must be performed at a temperature lower than the melting point of the coating after hot stamping. In order to ensure that the steel plate can be quenched and hardened under the above circumstances, the boron element can be added to delay the transformation of austenite to martensite and improve the hardenability of the steel plate or steel strip. The specific process of the hot stamping forming process of the present invention is as follows:
(1)加热：将涂覆锌或锌铁合金的钢板或钢带放入温度≥Ac 3(奥氏体化转变结束温度)的立式连续退火的加热炉中，以不低于5℃/s的加热速度将钢板或钢带 加热到高于Ac 3的温度，保温1～7分钟，使钢板或钢带奥氏体化均匀； (1) Heating: Put the steel plate or steel strip coated with zinc or zinc-iron alloy into a vertical continuous annealing furnace with a temperature ≥Ac 3 (austenite transformation end temperature), not less than 5℃/s The heating speed of the steel plate or steel strip is heated to a temperature higher than Ac 3 , and the temperature is kept for 1 to 7 minutes to make the austenite of the steel plate or steel strip uniform;
(2)热冲压成型与模内淬火：将落料后的钢板或钢带快速移动到热冲压模具上冲压成型淬火，成型温度范围为低于780℃，如570～780℃，优选400～650℃，可以在冲压成型前增加预冷。热冲压成型保压时间约3～15秒，冲压力为300～1000吨。热冲压成型完成后，钢板或钢带在模具中冷却，或从模具取出后冷却至室温，完成马氏体相变。(2) Hot stamping and in-mold quenching: The blanked steel plate or steel strip is quickly moved to the hot stamping die for stamping and quenching. The forming temperature range is less than 780℃, such as 570～780℃, preferably 400～650 ℃, pre-cooling can be added before stamping. The hot stamping forming pressure holding time is about 3 to 15 seconds, and the punching pressure is 300 to 1,000 tons. After the hot stamping is completed, the steel plate or steel strip is cooled in the mold, or taken out of the mold and then cooled to room temperature to complete the martensite transformation.
从图1可以看到本发明的方法可以将传统的带镀层热冲压用钢22MnB5在热冲压前后均含有脱碳层，且其原始奥氏体晶粒比传统热冲压钢板细化明显(图3和图4)，因此本发明中的热冲压零件冷弯性能大大提高(图5)。本发明所述的热冲压工艺还可以避免锌基镀层的热冲压钢板冲压成型后由于液态金属脆性(Liquid Metal Embrittlement，以下标记为LME)引起的基体裂纹，对锌基热冲压用钢的发展具有重要意义。It can be seen from FIG. 1 that the method of the present invention can make the conventional coated hot stamping steel 22MnB5 contain a decarburized layer before and after hot stamping, and its original austenite grains are more refined than the traditional hot stamped steel sheet (FIG. 3 And Figure 4), therefore, the cold bending performance of the hot stamping part in the present invention is greatly improved (Figure 5). The hot stamping process described in the present invention can also avoid matrix cracks caused by liquid metal brittleness (Liquid Metal Embrittlement, hereinafter referred to as LME) after stamping of hot stamping steel sheets with zinc-based coatings. Significance.
本发明的有益效果：本发明得到的热冲压零件，其冷弯性能优于传统的热冲压零件，对热冲压用钢的发展具有重要意义。优选地，以VDA238-100标准测试方法测得的本发明锌系镀覆热成型钢板或钢带的冷弯角度≥50度，优选≥55度，更优选≥60度。The beneficial effects of the present invention: The hot stamping parts obtained by the present invention have better cold bending performance than traditional hot stamping parts, and are of great significance to the development of hot stamping steel. Preferably, the cold bending angle of the zinc-plated hot-formed steel sheet or steel strip of the present invention measured by the VDA238-100 standard test method is ≥50 degrees, preferably ≥55 degrees, more preferably ≥60 degrees.
附图说明BRIEF DESCRIPTION
图1是本发明实施例3热成型钢板的截面金相(热成形后)；Fig. 1 is a cross-sectional metallography of a hot-formed steel plate of Example 3 of the present invention (after hot forming);
图2是本发明实施例3热成型钢板截面内氧化层金相(热成形前)；Figure 2 is the metallography of the oxide layer in the section of the hot-formed steel plate of the present invention (before hot-forming);
图3是本发明例实施例3热成型钢板原始奥氏体晶粒图片；3 is a picture of the original austenite grains of the hot-formed steel plate of Example 3 of the present invention;
图4是对比例热成型钢板原始奥氏体晶粒图片；4 is a picture of the original austenite grains of the hot-formed steel sheet of the comparative example;
图5是本发明钢板实施例5与对比例钢板热成型之后冷弯角度对比图。FIG. 5 is a comparison diagram of cold bending angles of the steel plate of Example 5 of the present invention and the comparative steel plate after hot forming.
具体实施方式detailed description
下面结合实施例和附图对本发明做进一步说明。The present invention will be further described below with reference to embodiments and drawings.
本发明实施例参见表1及表2。See Table 1 and Table 2 for embodiments of the present invention.
熔炼并铸造了具有表1所示化学成分的钢板1～6。将这些钢板加热到1230℃控制轧制，终轧温度为900℃，然后在600℃卷曲温度下得到厚度约3mm的热轧钢板， 将该热轧钢板酸洗后冷轧至厚度1.4mm的轧硬板。Steel plates 1 to 6 having chemical compositions shown in Table 1 were melted and cast. These steel sheets were heated to 1230°C to control rolling, the final rolling temperature was 900°C, and then a hot-rolled steel sheet with a thickness of about 3 mm was obtained at a coiling temperature of 600°C. The hot-rolled steel sheet was pickled and cold-rolled to a thickness of 1.4 mm. hard Board.
按照表2的条件将上述轧硬板再结晶退火并热镀锌得到镀锌钢板，再将这些钢板在930℃下保温4分钟后，再按照表3中的成形工艺，送至模具中成形至B柱零件。According to the conditions in Table 2, the above-mentioned hard-rolled plates are recrystallized and annealed and hot-dip galvanized to obtain galvanized steel plates. After these plates are kept at 930°C for 4 minutes, they are sent to the mold according to the forming process in Table 3 to form B-pillar parts.
根据表1的对比例和实施例，对比例6由于未添加Nb元素，其原始奥氏体晶粒(图4)中可见晶粒尺寸比实施例3(图3)明显粗大。对比表2的实施例和对比例结果可见，在连续热镀锌过程中，加热炉中的露点如果太低(如对比例6)，基板的脱碳层厚度为0μm，根据VDA238-100标准测试方法测定冷弯角度，如图5所示，结果可见其冷弯性能比实施例明显差。对比表3中的对比例和实施例结果可见在常规热冲压条件下，当钢板转移出加热炉转移至模具中时，如未施加预冷，零件中会产生裂纹(如对比例6)。因此，按照本发明方法生产的钢板及热冲压工艺具有良好的使用性能。另外，按照本发明方法生产的锌系镀覆热成型钢板或钢带根据JIS13B测试，其抗拉强度大于1400MPa，断后延伸率大于5％。According to the comparative example and the example of Table 1, since the Nb element is not added, the crystal grain size in the original austenite grains (FIG. 4) is significantly larger than that in the example 3 (FIG. 3 ). Comparing the results of the examples and comparative examples in Table 2, it can be seen that during the continuous hot-dip galvanizing process, if the dew point in the heating furnace is too low (such as Comparative Example 6), the thickness of the decarburized layer of the substrate is 0 μm, according to the VDA238-100 standard The method was used to determine the angle of cold bending, as shown in FIG. 5. As a result, it can be seen that its cold bending performance is significantly inferior to the examples. Comparing the comparative examples in Table 3 and the results of the examples, it can be seen that under normal hot stamping conditions, when the steel plate is transferred out of the heating furnace and transferred to the mold, if no pre-cooling is applied, cracks will occur in the part (such as Comparative Example 6). Therefore, the steel plate and hot stamping process produced according to the method of the present invention have good serviceability. In addition, the zinc-based plated hot-formed steel sheet or steel strip produced according to the method of the present invention has a tensile strength greater than 1400 MPa and an elongation after fracture greater than 5% according to JIS13B testing.
表1Table 1
编号Numbering CC SiSi MnMn PP SS AlAl TiTi BB CrCr MoMo NbNb 备注Remarks
11 0.150.15 0.220.22 3.03.0 0.010.01 0.0010.001 0.070.07 0.010.01 0.00200.0020  A  A 0.030.03 发明例Invention example
22 0.200.20 0.040.04 1.41.4 0.010.01 0.0020.002 0.030.03 0.020.02 0.00300.0030 0.20.2  A 0.030.03 发明例Invention example
33 0.300.30 0.060.06 0.70.7 0.020.02 0.0020.002 0.010.01 0.020.02 0.00300.0030  A 0.10.1 0.030.03 发明例Invention example
44 0.210.21 0.600.60 1.21.2 0.010.01 0.0010.001 0.040.04 0.030.03 0.00300.0030  A 0.050.05 0.030.03 发明例Invention example
55 0.720.72 1.701.70 0.90.9 0.010.01 0.0010.001 0.030.03 0.020.02 0.00150.0015  A  A 0.040.04 发明例Invention example
66 0.210.21 0.040.04 1.31.3 0.010.01 0.0010.001 0.030.03 0.020.02 0.00200.0020  A  A  A 对比例Comparative example
表2Table 2
Figure PCTCN2019121860-appb-000001
Figure PCTCN2019121860-appb-000001
Figure PCTCN2019121860-appb-000002
Figure PCTCN2019121860-appb-000002
表3table 3
Figure PCTCN2019121860-appb-000003
Figure PCTCN2019121860-appb-000003

Claims (14)

  1. 一种冷弯性能优良的锌系镀覆热成型钢板或钢带，其特征在于，所述锌系镀覆热成型钢板或钢带包括表面脱碳层厚度在25μm以下的基板及其上附着量为10～100g/m 2的锌系镀层；以重量百分比计，所述基板含有：C：0.1～0.8％、Si：0.05～2.0％、Mn：0.5～3.0％、P≤0.1％、S≤0.05％、Al≤0.1％、N≤0.01％，余下为Fe和不可避免的杂质；所述基板的原始奥氏体晶粒平均尺寸在15μm以下。 A zinc-plated hot-formed steel sheet or steel strip with excellent cold bending performance, characterized in that the zinc-based coated hot-formed steel sheet or steel strip includes a substrate with a surface decarburization layer thickness of 25 μm or less and the amount of adhesion thereon It is a zinc-based plating layer of 10 to 100 g/m 2 ; in terms of weight percentage, the substrate contains: C: 0.1 to 0.8%, Si: 0.05 to 2.0%, Mn: 0.5 to 3.0%, P≤0.1%, S≤ 0.05%, Al≤0.1%, N≤0.01%, the balance is Fe and inevitable impurities; the average size of the original austenite grains of the substrate is below 15 μm.
  2. 根据权利要求1所述的冷弯性能优良的锌系镀覆热成型钢板或钢带，其特征在于，所述锌系镀层为纯锌镀层或者含有10％～20％Fe的锌铁合金镀层。The zinc-based plated hot-formed steel sheet or steel strip having excellent cold bending performance according to claim 1, wherein the zinc-based coating is a pure zinc coating or a zinc-iron alloy coating containing 10% to 20% Fe.
  3. 根据权利要求1或2所述的冷弯性能优良的锌系镀覆热成型钢板或钢带，其特征在于，所述基板成分还含有Cr：0.01～1.0％、Mo：0.01～1.0％、Ti≤0.2％、Nb：0.01～0.08％、V：0.01～1.0％、B：0.001～0.08％中至少一种。The zinc-plated hot-formed steel sheet or steel strip having excellent cold bending performance according to claim 1 or 2, wherein the substrate component further contains Cr: 0.01 to 1.0%, Mo: 0.01 to 1.0%, Ti At least one of ≤0.2%, Nb: 0.01 to 0.08%, V: 0.01 to 1.0%, B: 0.001 to 0.08%.
  4. 根据权利要求3所述的冷弯性能优良的锌系镀覆热成型钢板或钢带，其特征在于，所述基板成分中含有0.01～0.08％的Nb、0.005～0.05％的Ti和0.001～0.01％的B，和任选的0.1～0.3％的Cr和任选的0.01～0.2％的Mo。The zinc-plated hot-formed steel sheet or steel strip having excellent cold bending performance according to claim 3, wherein the substrate component contains 0.01 to 0.08% of Nb, 0.005 to 0.05% of Ti, and 0.001 to 0.01 % B, and optionally 0.1-0.3% Cr and optionally 0.01-0.2% Mo.
  5. 根据权利要求1所述的冷弯性能优良的锌系镀覆热成型钢板或钢带，其特征在于，所述基板成分为：C：0.1～0.8％、Si：0.05～2.0％、Mn：0.5～3.0％、P≤0.05％、S≤0.01％、Al：0.01-0.1％、Ti：0.005-0.05％、N≤0.01％、B：0.001-0.004％、Nb：0.02-0.05％，以及任选的0.1-0.3％的Cr和0.01-0.2％的Mo中的一种或两种，余下为Fe和不可避免的杂质。The zinc-plated hot-formed steel sheet or steel strip having excellent cold bending performance according to claim 1, wherein the substrate composition is: C: 0.1 to 0.8%, Si: 0.05 to 2.0%, and Mn: 0.5 ~3.0%, P≤0.05%, S≤0.01%, Al: 0.01-0.1%, Ti: 0.005-0.05%, N≤0.01%, B: 0.001-0.004%, Nb: 0.02-0.05%, and optional One or two of 0.1-0.3% Cr and 0.01-0.2% Mo, the balance is Fe and inevitable impurities.
  6. 根据权利要求1所述的冷弯性能优良的锌系镀覆热成型钢板或钢带，其特征在于，以VDA238-100标准测试方法测得的所述锌系镀覆热成型钢板或钢带的冷弯角度≥50度。The zinc-plated hot-formed steel sheet or steel strip with excellent cold bending performance according to claim 1, characterized in that the zinc-based coated hot-formed steel sheet or steel strip measured by the VDA238-100 standard test method Cold bending angle ≥50 degrees.
  7. 根据权利要求1～6中任何一项所述的冷弯性能优良的锌系镀覆热成型钢板或钢带的制造方法，其特征是：包括如下步骤：The method for manufacturing a zinc-plated hot-formed steel sheet or steel strip having excellent cold bending performance according to any one of claims 1 to 6, characterized in that it includes the following steps:
    1)按权利要求1-4中任一项所述的成分冶炼、连铸生产铸坯；1) Production of casting slabs by smelting and continuous casting according to any one of claims 1-4;
    2)热轧：将铸坯加热到1100～1250℃后控制轧制，开轧温度为950～1150℃，终轧温度为750～900℃，热轧板厚度小于等于20mm；2) Hot rolling: The cast billet is heated to 1100～1250℃ and then controlled to roll. The open rolling temperature is 950～1150℃, the final rolling temperature is 750～900℃, and the thickness of the hot rolled sheet is less than or equal to 20mm;
    3)轧后在500～850℃进行卷取，冷却至室温后组织为铁素体和珠光体组织；3) After rolling, coiling is carried out at 500～850℃, and the structure is ferrite and pearlite after cooling to room temperature;
    4)酸洗以去除热轧过程中产生的氧化铁皮；4) Pickling to remove the scale produced during hot rolling;
    5)冷轧：将钢卷冷轧至2.0mm以下的厚度，冷轧压下量≥35％；5) Cold rolling: Cold rolling the steel coil to a thickness below 2.0 mm, the cold rolling reduction ≥ 35%;
    6)退火和镀锌：将钢卷在-40～30℃的露点范围内加热到500-850℃，使钢卷在镀锌前具有25μm以下的脱碳层，然后在1～30体积百分数％的H 2范围内，以10～30℃/s的冷却速度冷却至400～500℃，保温0～100s，随后浸镀到镀液中，镀液温度为440～480℃，最后以≥30℃/s冷却速度冷却至室温。 6) Annealing and galvanizing: heat the steel coil in the dew point range of -40～30℃ to 500-850℃, so that the steel coil has a decarburized layer below 25μm before galvanizing, and then 1-30 volume percent Within the range of H 2 , it is cooled to 400～500℃ at a cooling rate of 10～30℃/s, and kept at 0～100s, and then immersed in the plating solution, the temperature of the plating solution is 440～480℃, and finally at ≥30℃ /s Cooling rate to room temperature.
  8. 根据权利要求7所述的冷弯性能优良的锌系镀覆热成型钢板或钢带的制造方法，其特征是：镀层为合金化镀层，在热浸镀锌处理后，用气炉或感应加热炉进行再加热，合金化温度设定为480℃以上，优选为500～650℃。The method for manufacturing a zinc-plated hot-formed steel sheet or steel strip having excellent cold bending performance according to claim 7, characterized in that the coating is an alloyed coating, and after hot dip galvanizing, a gas furnace or induction heating is used The furnace is reheated, and the alloying temperature is set to 480°C or higher, preferably 500 to 650°C.
  9. 根据权利要求7所述的冷弯性能优良的锌系镀覆热成型钢板或钢带的制造方法，其特征是：还包括如下热冲压成型步骤：The method for manufacturing a zinc-plated hot-formed steel sheet or steel strip with excellent cold bending performance according to claim 7, further comprising the following hot stamping steps:
    a)加热：将钢板或钢带放入连续退火的加热炉中，以大于5℃/s的加热速度将钢板或钢带加热到高于Ac3的温度，保温时间1-10分钟，使钢板或钢带奥氏体化均匀；a) Heating: Put the steel plate or steel strip in a continuous annealing furnace, and heat the steel plate or steel strip to a temperature higher than Ac3 at a heating rate of more than 5°C/s. The holding time is 1-10 minutes. The austenite of the steel strip is uniform;
    b)热冲压成型与模内淬火：将完全奥氏体化的钢板或钢带移动到热冲压模具上冲压成型淬火，成型温度范围为低于780℃，优选400～650℃，热冲压成型保压时间3～15秒，冲压力为300～1000吨；热冲压成型完成后，钢板或钢带在模具中冷却，并在模具中冷却至室温，或从模具取出后冷却至室温，完成马氏体相变。b) Hot stamping and in-mold quenching: Move the fully austenitized steel plate or steel strip to the hot stamping die for stamping and quenching. The forming temperature range is lower than 780℃, preferably 400～650℃. Pressing time 3-15 seconds, punching pressure 300-1000 tons; after hot stamping, the steel plate or steel strip is cooled in the mold and cooled to room temperature in the mold, or cooled to room temperature after being removed from the mold Body phase change.
  10. 根据权利要求9所述的冷弯性能优良的锌系镀覆热成型钢板或钢带的制造方法，其特征是：所述的步骤b)中，冲压成型前预冷钢板或钢带，预冷却速度大于30℃/s。The method for manufacturing a zinc-plated hot-formed steel sheet or steel strip having excellent cold bending performance according to claim 9, wherein in the step b), the steel sheet or steel strip is pre-cooled before stamping and pre-cooled The speed is greater than 30°C/s.
  11. 根据权利要求9所述的冷弯性能优良的锌系镀覆热成型钢板或钢带的制造方法，其特征是：所述的步骤b)中钢板或钢带在模具中以大于30℃/s的冷却速度冷却至室温。The method for manufacturing a zinc-plated hot-formed steel sheet or steel strip with excellent cold bending performance according to claim 9, characterized in that: in the step b), the steel sheet or steel strip is in the mold at a temperature greater than 30°C/s Cooling rate to room temperature.
  12. 根据权利要求7所述的冷弯性能优良的锌系镀覆热成型钢板或钢带的制造方法，其特征是：所述步骤5)中所述的冷轧压下量为50～60％。The method for manufacturing a zinc-plated hot-formed steel sheet or steel strip having excellent cold bending performance according to claim 7, wherein the cold rolling reduction in the step 5) is 50 to 60%.
  13. 根据权利要求7所述的冷弯性能优良的锌系镀覆热成型钢板或钢带的制造方法，其特征是：所述步骤6)中，钢卷在0～10℃的露点范围内加热到500-800℃。The method for manufacturing a zinc-plated hot-formed steel sheet or steel strip having excellent cold bending performance according to claim 7, wherein in the step 6), the steel coil is heated to a dew point ranging from 0 to 10°C to 500-800℃.
  14. 根据权利要求9所述的冷弯性能优良的锌系镀覆热成型钢板或钢带的制造方法，其特征是：所述锌系镀覆热成型钢板或钢带的抗拉强度大于1400MPa，断后延伸率大于5％。The method for manufacturing a zinc-based plated hot-formed steel sheet or steel strip with excellent cold bending performance according to claim 9, wherein the tensile strength of the zinc-based plated hot-formed steel sheet or steel strip is greater than 1400 MPa, after breaking The elongation is greater than 5%.
PCT/CN2019/121860 2018-11-30 2019-11-29 Zinc-based plated hot-formed steel plate or steel strip having excellent cold bending performance, and manufacturing method thereof WO2020108594A1 (en)

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