WO2021248626A1 - 一种锰系镀覆钢板及其热成型方法和热成型产品 - Google Patents

一种锰系镀覆钢板及其热成型方法和热成型产品 Download PDF

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WO2021248626A1
WO2021248626A1 PCT/CN2020/102264 CN2020102264W WO2021248626A1 WO 2021248626 A1 WO2021248626 A1 WO 2021248626A1 CN 2020102264 W CN2020102264 W CN 2020102264W WO 2021248626 A1 WO2021248626 A1 WO 2021248626A1
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manganese
steel sheet
steel plate
layer
alloy
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French (fr)
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安健
陈汉杰
于振
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苏州普热斯勒先进成型技术有限公司
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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
    • C22C38/04—Ferrous alloys, e.g. steel alloys containing manganese
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B21—MECHANICAL METAL-WORKING WITHOUT ESSENTIALLY REMOVING MATERIAL; PUNCHING METAL
    • B21D—WORKING OR PROCESSING OF SHEET METAL OR METAL TUBES, RODS OR PROFILES WITHOUT ESSENTIALLY REMOVING MATERIAL; PUNCHING METAL
    • B21D37/00—Tools as parts of machines covered by this subclass
    • B21D37/16—Heating or cooling
    • 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
    • C21D1/74—Methods of treatment in inert gas, controlled atmosphere, vacuum or pulverulent material
    • 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
    • C21D1/74—Methods of treatment in inert gas, controlled atmosphere, vacuum or pulverulent material
    • C21D1/773—Methods of treatment in inert gas, controlled atmosphere, vacuum or pulverulent material under reduced pressure or vacuum
    • C—CHEMISTRY; METALLURGY
    • C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
    • C22C—ALLOYS
    • C22C38/00—Ferrous alloys, e.g. steel alloys
    • C22C38/06—Ferrous alloys, e.g. steel alloys containing aluminium
    • C—CHEMISTRY; METALLURGY
    • C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
    • C22C—ALLOYS
    • C22C38/00—Ferrous alloys, e.g. steel alloys
    • C22C38/12—Ferrous alloys, e.g. steel alloys containing tungsten, tantalum, molybdenum, vanadium, or niobium
    • C—CHEMISTRY; METALLURGY
    • C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
    • C22C—ALLOYS
    • C22C38/00—Ferrous alloys, e.g. steel alloys
    • C22C38/14—Ferrous alloys, e.g. steel alloys containing titanium or zirconium
    • C—CHEMISTRY; METALLURGY
    • C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
    • C22C—ALLOYS
    • C22C38/00—Ferrous alloys, e.g. steel alloys
    • C22C38/16—Ferrous alloys, e.g. steel alloys containing copper
    • C—CHEMISTRY; METALLURGY
    • C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
    • C22C—ALLOYS
    • C22C38/00—Ferrous alloys, e.g. steel alloys
    • C22C38/18—Ferrous alloys, e.g. steel alloys containing chromium
    • C22C38/20—Ferrous alloys, e.g. steel alloys containing chromium with copper
    • C—CHEMISTRY; METALLURGY
    • C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
    • C22C—ALLOYS
    • C22C38/00—Ferrous alloys, e.g. steel alloys
    • C22C38/18—Ferrous alloys, e.g. steel alloys containing chromium
    • C22C38/22—Ferrous alloys, e.g. steel alloys containing chromium with molybdenum or tungsten
    • C—CHEMISTRY; METALLURGY
    • C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
    • C22C—ALLOYS
    • C22C38/00—Ferrous alloys, e.g. steel alloys
    • C22C38/18—Ferrous alloys, e.g. steel alloys containing chromium
    • C22C38/24—Ferrous alloys, e.g. steel alloys containing chromium with vanadium
    • C—CHEMISTRY; METALLURGY
    • C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
    • C22C—ALLOYS
    • C22C38/00—Ferrous alloys, e.g. steel alloys
    • C22C38/18—Ferrous alloys, e.g. steel alloys containing chromium
    • C22C38/26—Ferrous alloys, e.g. steel alloys containing chromium with niobium or tantalum
    • C—CHEMISTRY; METALLURGY
    • C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
    • C22C—ALLOYS
    • C22C38/00—Ferrous alloys, e.g. steel alloys
    • C22C38/18—Ferrous alloys, e.g. steel alloys containing chromium
    • C22C38/28—Ferrous alloys, e.g. steel alloys containing chromium with titanium or zirconium
    • C—CHEMISTRY; METALLURGY
    • C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
    • C22C—ALLOYS
    • C22C38/00—Ferrous alloys, e.g. steel alloys
    • C22C38/18—Ferrous alloys, e.g. steel alloys containing chromium
    • C22C38/32—Ferrous alloys, e.g. steel alloys containing chromium with boron
    • C—CHEMISTRY; METALLURGY
    • C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
    • C22C—ALLOYS
    • C22C38/00—Ferrous alloys, e.g. steel alloys
    • C22C38/18—Ferrous alloys, e.g. steel alloys containing chromium
    • C22C38/40—Ferrous alloys, e.g. steel alloys containing chromium with nickel
    • C22C38/42—Ferrous alloys, e.g. steel alloys containing chromium with nickel with copper
    • C—CHEMISTRY; METALLURGY
    • C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
    • C22C—ALLOYS
    • C22C38/00—Ferrous alloys, e.g. steel alloys
    • C22C38/18—Ferrous alloys, e.g. steel alloys containing chromium
    • C22C38/40—Ferrous alloys, e.g. steel alloys containing chromium with nickel
    • C22C38/44—Ferrous alloys, e.g. steel alloys containing chromium with nickel with molybdenum or tungsten
    • C—CHEMISTRY; METALLURGY
    • C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
    • C22C—ALLOYS
    • C22C38/00—Ferrous alloys, e.g. steel alloys
    • C22C38/18—Ferrous alloys, e.g. steel alloys containing chromium
    • C22C38/40—Ferrous alloys, e.g. steel alloys containing chromium with nickel
    • C22C38/46—Ferrous alloys, e.g. steel alloys containing chromium with nickel with vanadium
    • C—CHEMISTRY; METALLURGY
    • C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
    • C22C—ALLOYS
    • C22C38/00—Ferrous alloys, e.g. steel alloys
    • C22C38/18—Ferrous alloys, e.g. steel alloys containing chromium
    • C22C38/40—Ferrous alloys, e.g. steel alloys containing chromium with nickel
    • C22C38/48—Ferrous alloys, e.g. steel alloys containing chromium with nickel with niobium or tantalum
    • C—CHEMISTRY; METALLURGY
    • C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
    • C22C—ALLOYS
    • C22C38/00—Ferrous alloys, e.g. steel alloys
    • C22C38/18—Ferrous alloys, e.g. steel alloys containing chromium
    • C22C38/40—Ferrous alloys, e.g. steel alloys containing chromium with nickel
    • C22C38/50—Ferrous alloys, e.g. steel alloys containing chromium with nickel with titanium or zirconium
    • C—CHEMISTRY; METALLURGY
    • C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
    • C22C—ALLOYS
    • C22C38/00—Ferrous alloys, e.g. steel alloys
    • C22C38/18—Ferrous alloys, e.g. steel alloys containing chromium
    • C22C38/40—Ferrous alloys, e.g. steel alloys containing chromium with nickel
    • C22C38/54—Ferrous alloys, e.g. steel alloys containing chromium with nickel with boron

Definitions

  • the invention relates to the technical field of hot stamping and forming, in particular to a manganese-based plated steel plate and a hot forming method and a hot forming product.
  • aluminum-silicon coated steel plates such as the patent CN 108588612A, a kind of zinc Hot stamping forming method of coated steel sheet or steel strip
  • zinc-coated steel sheet such as patent CN107127238A hot stamping forming zinc-magnesium coated steel sheet and its manufacturing and hot stamping method
  • the aluminum-silicon coated steel sheet is heated in the air environment to effectively prevent the iron matrix from being oxidized during heating, it also has the following disadvantages:
  • the melting point of aluminum is only about 680°C, the aluminum-silicon coated steel sheet will melt during austenitization (usually higher than 860°C), and the molten coating will contaminate the furnace roll and stamping of the heating furnace. Mold, resulting in a decrease in the life of the furnace roll and mold.
  • the brittle intermetallic compound generated during the heating process of the aluminum-silicon coating produces a large number of cracks after cooling, and these cracks cause the corrosion resistance of the aluminum-silicon coating thermoformed product during service to decrease.
  • the aluminum-silicon coating has good low-temperature thermal conductivity, which makes the hot forming quenching cooling rate too high, and the matrix martensite structure is too late for self-tempering, resulting in poor cold bending performance of the aluminum-silicon coating hot forming product (referring to Metal materials can withstand bending without breaking performance at room temperature).
  • the relative increase in surface carbon content is also an important reason for the poor cold bending performance of its hot-formed products (far inferior to uncoated steel hot-formed products).
  • the aluminum-silicon coating undergoes melting and solidification during the heating and cooling process of hot forming, and produces brittle intermetallic compounds. These all lead to the roughening of the coating surface, making the surface roughness of the coating much higher than that of heat. Shape the coated surface before heating. The higher friction coefficient of the coating surface is not conducive to the material flow during the stamping process, thereby reducing the forming performance of the steel plate.
  • the zinc-coated steel sheet not only has the ability to prevent the iron matrix of the hot-formed steel from being oxidized during austenitization and heating in the air, but also has a sacrificial anode protection function to improve the corrosion resistance of the zinc-coated steel hot-formed product during service. performance.
  • the zinc-coated steel sheet also causes cracks in the substrate due to the brittleness of the liquid metal. Therefore, zinc-coated steel sheets are mostly used in indirect hot forming manufacturing methods.
  • the embodiments of the present invention provide a manganese-based plated steel sheet and a hot forming method and a hot forming product thereof, which are used to solve at least one of the above-mentioned problems.
  • a manganese-based coated steel sheet comprising a steel sheet and manganese-based coating layers provided on both sides of the steel sheet, wherein the adhesion amount of the manganese-based coating layer on the steel sheet is 40g/ Between m2 and 110g/m2, the content of Mn in the manganese-based plating layer is greater than or equal to 80% by mass%.
  • the adhesion amount of the manganese-based coating layer on the steel plate is between 70 g/m2 and 100 g/m2.
  • the manganese-based plating layer includes pure manganese, manganese-iron alloy, manganese-zinc alloy, manganese-aluminum alloy, manganese-nickel alloy, manganese-zinc-nickel alloy, manganese-aluminum-nickel alloy, manganese-chromium alloy, manganese-zinc-chromium alloy or manganese aluminum One or more of chromium alloys.
  • the steel plate is calculated by mass%, wherein the content of each component is C: 0.1% to 0.4%, Mn: 0.5% to 2.0%, Al: 0.005% to 0.1%, and B: 0.001% to 0.010%.
  • the steel sheet further includes, in terms of mass %, one or more of Ti: 0.01% to 0.20%, and/or Nb: 0.01% to 0.20%, and/or V: 0.1% to 0.5% .
  • the steel sheet further includes, in terms of mass %, Cr: 0.1% to 0.5%, and/or Mo: 0.1% to 0.5%, and/or Cu: 0.1% to 0.5%, and/or Ni: 0.1 One or more of % ⁇ 0.5%.
  • the manganese-based plating layer is attached to the steel plate through an electroplating process.
  • the two manganese-based plating layers are further provided with a nickel plating layer or an iron plating layer on the side away from the steel plate, and the thickness of the nickel plating layer or the iron plating layer is less than 1 ⁇ m.
  • the embodiment of the present application also discloses: a hot forming method of the manganese-based plated steel sheet as described in the present embodiment, including the following steps:
  • the manganese-based coated steel sheet is placed in a heating furnace and heated to 860-950°C to austenitize the steel sheet in the manganese-based coated steel sheet.
  • the content of oxygen in the heating furnace is less than 0.02%;
  • the manganese-based plated steel sheet heated to 860-950°C is placed in a mold to form a thermoformed product.
  • the heating furnace is a vacuum heating furnace.
  • the austenite holding time is between 0 and 10 minutes.
  • nitrogen gas with a purity of 99.999% or more is introduced into the vacuum heating furnace to pre-cool the manganese-based coated steel sheet for 1 to 10 seconds,
  • the temperature of the manganese-based plated steel sheet after pre-cooling is between 600 and 860°C.
  • the pre-cooling time of the manganese-based plated steel sheet is between 1 and 3 seconds.
  • the temperature of the manganese-based plated steel sheet after pre-cooling is between 750 and 800°C.
  • the heating furnace is a protective atmosphere furnace.
  • the oxygen content in the heating furnace is less than 0.002% in terms of mass%.
  • the manganese-based plated steel sheet is fed into the mold under the protection of a protective atmosphere, the mold is set in the protective atmosphere, and the oxygen content in the protective atmosphere is calculated by mass% Less than 3%.
  • the temperature of the manganese-based plated steel sheet at the moment of closing the mold is greater than 550°C.
  • thermoformed product which is prepared by adopting the manganese-based plated steel plate and the thermoforming method in this embodiment.
  • the manganese-based coating layer of the hot formed product includes a ⁇ -phase iron-manganese solid solution alloy layer attached to the surface of the steel plate and a ⁇ -phase ferromanganese solid solution attached to the side of the ⁇ -phase iron-manganese solid solution layer away from the steel plate. Alloy layer.
  • the thickness of the ⁇ -phase iron-manganese solid solution alloy layer is not less than 1 ⁇ m, the thickness of the ⁇ -phase ferromanganese solid solution alloy layer is between 5 and 15 ⁇ m, and the ⁇ -phase iron-manganese solid solution alloy layer and the ⁇ phase The total thickness of the phase ferromanganese solid solution alloy layer is between 6 and 20 ⁇ m.
  • the Mn content in the manganese-based plating layer is greater than or equal to 80%.
  • the melting point of Mn alloy is about 1200°C, which is much higher than the austenitizing temperature of the steel sheet (usually lower than 950°C). Therefore, the manganese-based coating layer of the manganese-based plated steel plate is not It will melt, so it will not contaminate the furnace roller, nor will it contaminate the mold when it is formed in the mold.
  • the manganese-based plating layer does not melt, it is not necessary to provide additional low-temperature heating time to alloy Mn and Fe in the steel sheet. Therefore, as shown in Figure 2, under the condition that the steel plate is heated uniformly, the heating rate of the steel plate can be as fast as possible, and the rate of the steel plate during the entire heating process can be kept constant to improve production efficiency and reduce energy consumption.
  • the hot-formed product prepared by the method in this embodiment and the manganese-plated steel plate due to the high-temperature heating process of the hot-forming, the manganese element in the manganese-plated layer diffuses into the steel plate matrix to form room temperature austenite
  • the structure, the low temperature thermal conductivity of the room temperature austenite structure is much lower than that of the steel sheet itself, which is equivalent to forming a poor thermal conductor on the surface of the steel sheet in the temperature range below 250°C.
  • the above room temperature austenite structure delays the further rapid cooling of the steel plate by the mold, so that the quenched martensite of the steel plate can fully self-temper and improve the product The toughness and cold bending performance.
  • the coating layer on the surface of the steel plate includes two structures, one is the ⁇ -phase iron-manganese solid solution alloy layer covering the surface of the steel plate, and the other is the ⁇ -phase iron-manganese solid solution alloy layer covering the surface of the steel plate.
  • the thickness of the ⁇ -phase ferromanganese solid solution alloy layer is not less than 1 ⁇ m, the thickness of the ⁇ -phase ferromanganese solid solution alloy layer is between 5 and 15 ⁇ m, and the total thickness of the ⁇ -phase ferromanganese solid solution alloy layer and the ⁇ -phase ferromanganese solid solution alloy layer It is between 6 and 20 ⁇ m, preferably, the thickness of the ⁇ -phase iron-manganese solid solution alloy layer is between 1 and 3 ⁇ m. Both the ⁇ -phase ferromanganese solid solution alloy layer and the ⁇ -phase ferromanganese solid solution alloy layer can make the coating layer on the surface of the product have good toughness and plasticity. Therefore, the steel plate and the coating layer on the surface of the product have good cold bending properties. .
  • the iron and manganese-based coating layers in the steel sheet will form a solid solution when they diffuse each other Alloys do not form brittle intermetallic compounds. Therefore, there are no cracks in the steel plate and the coating layer of the hot formed product, and the structure of the coating layer is dense, so that the hot formed product has excellent corrosion resistance.
  • the manganese-based coating is an anodic coating, which can provide electrochemical protection.
  • the manganese-based coating has a stronger self-passivation ability after being corroded, and the corrosion current is higher than that of the zinc-based coating.
  • the coating should be small. Therefore, the corrosion resistance of the thermoformed product during service is further improved.
  • thermoformed product in this embodiment has good laser welding performance and spot welding performance.
  • thermoformed product in this embodiment is carried out in an environment with a very low oxygen content during the austenitizing heating and transfer of the blank to the mold, and even during the mold closing process. Therefore, The amount of oxidation of the billet during the heating process is very small.
  • the billet after heating has a good appearance such as low surface roughness and smooth surface, and the manganese-based coating layer of the billet after heating is dense, and the spreading thickness of the coating layer is small. It is beneficial to improve the forming performance of the blank.
  • Fig. 1 is a temperature rise curve diagram of a steel sheet with aluminum-silicon coating in the prior art during austenitizing heating
  • Fig. 2 is a temperature rise curve diagram of the manganese-based plated steel sheet during austenitization heating in an embodiment of the present invention
  • FIG. 3 is a schematic diagram of the tensile test results of tailor-welded blanks after tailor-welded manganese-based plated steel sheets in an embodiment of the present invention
  • Figure 4 is a schematic diagram of the surface change of a hot formed product made of aluminum-silicon coated steel plate after 6 hours of salt spray test;
  • thermoformed product 5 is a schematic diagram of the surface change of the thermoformed product in this embodiment after 120 hours of salt spray test
  • Figure 6 is an SEM image of the thermoformed product in Case 1 in this embodiment
  • Figure 7 is an XRD diagram of the thermoformed product in Case 1 in this embodiment.
  • Figure 8 is an SEM image of the thermoformed product in Case 3 in this embodiment.
  • Fig. 9 is an XRD chart of the thermoformed product in Case 3 in this embodiment.
  • the manganese-based plated steel sheet in this embodiment includes a steel sheet and manganese-based coating layers provided on both sides of the steel sheet. That is, in this embodiment, both the front and back sides of the steel sheet have manganese-based coating layers.
  • the adhesion amount of the manganese-based coating layer on the steel plate is between 40g/m2 ⁇ 110g/m2 (converted to a thickness of 5 ⁇ 15mm), that is, 40 ⁇ 110g is deposited on the steel plate per square meter.
  • the adhesion amount of the manganese-based coating layer on the steel plate is between 70g/m2 ⁇ 100g/m2 (converted to a thickness of 9 ⁇ 14mm).
  • the Mn content in the manganese-based plating layer is 80% or more.
  • the melting point of Mn alloy is about 1200°C, which is much higher than the austenitizing temperature of the steel sheet (usually lower than 950°C). Therefore, the manganese-based coating layer of the manganese-based plated steel plate is not It will melt, so it will not contaminate the furnace roller, nor will it contaminate the mold when it is formed in the mold.
  • the manganese-based plating layer does not melt, it is not necessary to provide additional low-temperature heating time to alloy Mn and Fe in the steel sheet. Therefore, as shown in Figure 2, under the condition that the steel plate is heated uniformly, the heating rate of the steel plate can be as fast as possible, and the rate of the steel plate during the entire heating process can be kept constant to improve production efficiency and reduce energy consumption.
  • the overall performance of the steel sheet with the manganese-based coating layer with an adhesion amount of 40 g/m2 to 110 g/m2 in this embodiment is better.
  • the manganese-based coating in this embodiment may include pure manganese, manganese-iron alloy, manganese-zinc alloy, manganese aluminum alloy, manganese-nickel alloy, manganese-zinc-nickel alloy, manganese-aluminum-nickel alloy, manganese-chromium alloy, manganese-zinc-chromium alloy or manganese One or more of aluminum-chromium alloys.
  • the raw materials used to form the manganese-based coating layer of this embodiment may include pure manganese, manganese-iron alloy, manganese-zinc alloy, manganese-aluminum alloy, manganese-nickel alloy, manganese-zinc-nickel alloy, manganese-aluminum-nickel alloy, and manganese-chromium alloy.
  • the mass fraction of aluminum is less than 0.5% to prevent the aluminum in the coating layer from reacting with the iron in the steel plate to form brittle iron-aluminum alloy; and the manganese-based coating layer
  • the content of the low melting point alloy in the medium is preferably controlled below 5%, so as to prevent the melting of the low melting point alloy from contaminating the furnace roll of the heating furnace during the high-temperature heating process.
  • the steel plate in this embodiment is calculated by mass%, which may include C: 0.1% to 0.4%, Mn: 0.5% to 2.0%, Al: 0.005% to 0.1%, B: 0.001% to 0.010%, and the remaining The amount is Fe.
  • C is a very important element that improves the hardenability of the steel sheet and mainly determines the strength after quenching.
  • the C content is set to 0.1% or more; on the other hand, when the C content exceeds 0.4%, the toughness after quenching deteriorates significantly and the weldability is poor.
  • the C content is set to 0.4% or less, preferably 0.3% or less, that is, the C content is preferably 0.1% to 0.3%.
  • Mn is a very effective element for improving the hardenability of the steel sheet and stably ensuring the strength after quenching. When the Mn content is less than 0.5%, the effect is insufficient. Therefore, the Mn content is set to 0.5% or more, preferably 1% or more; on the other hand, when the Mn content exceeds 2.0%, not only the effect is saturated, but on the contrary, there is also It is difficult to ensure stable strength after quenching. Therefore, the Mn content is set to 2.0% or less, preferably 1.5% or less, that is, the Mn content is preferably 1% to 1.5%.
  • A1 has the function of deoxidizing steel and perfecting steel.
  • the Al content is set to 0.005% or more; when the Al content exceeds 0.1%, the effect based on the above-mentioned effect is saturated, which is disadvantageous in terms of cost. Therefore, the A1 content is set to 0.1% or less.
  • B is an element that can improve the hardenability of the steel sheet. During the hot forming process of the steel sheet, it prevents the austenite in the steel sheet from transforming to ferrite and causes the strength of the steel sheet to decrease.
  • the B content is set to 0.001% to 0.010%, preferably 0.001 % ⁇ 0.008%.
  • the steel plate may also contain one or more of Ti: 0.01% to 0.20%, Nb: 0.01% to 0.20%, and V: 0.1% to 0.5%.
  • the steel sheet may also include one or more of Ti, Nb, and V.
  • Ti, Nb, and V can precipitate certain composite carbides during the austenitization process to refine the original austenite grains and increase the strength of the material.
  • the total content of Ti and Nb exceeds 0.20%, or when the content of V exceeds 1.0%, the effect based on the above action is saturated, which is disadvantageous in terms of cost. Therefore, the total content of Ti and Nb is set to 0.20% or less, and the content of V is set to 1.0% or less.
  • the contents of Ti and Nb are each 0.15% or less, and V is 0.5% or less. In order to obtain the above-mentioned effects more reliably, it is preferable to set the content of Ti and Nb to 0.01% or more, and to set the content of V to 0.1% or more.
  • the steel plate may also include one of Cr: 0.1% to 0.5%, Mo: 0.1% to 0.5%, Cu: 0.1% to 0.5%, Ni: 0.1% to 0.5%, or Many kinds.
  • the steel sheet may also include one or more of Cr, Mo, Cu, and Ni.
  • Cr, Mo, Cu, and Ni When the steel sheet contains Cr, the content of Cr in the steel sheet is 0.1% to 0.5%; when the steel sheet contains Mo , The Mo content in the steel sheet is 0.1% to 0.5%; when the steel sheet contains Cu, the Cu content in the steel sheet is 0.1% to 0.5%; when the steel sheet contains Ni, the Ni content in the steel sheet is 0.1% to 0.5%.
  • Cr, Mo, Cu, and Ni can improve the hardenability of the steel sheet and stably ensure the strength after quenching.
  • the manganese-based plating layer in this embodiment can be attached to the steel plate by an electroplating process.
  • the electroplating method is cold plating (under normal temperature), so it can avoid the oxidation of manganese during the electroplating process. At the same time, the electroplating method can be Has a higher efficiency.
  • the manganese-based plating layer may also be provided with a nickel plating layer or iron plating layer with a thickness of less than 1 ⁇ m, that is, a thickness of the manganese-based plating layer may be provided on the side away from the steel plate.
  • Nickel plating layer or iron plating layer less than 1 ⁇ m.
  • the nickel plating layer or iron plating layer can prevent the manganese on the surface of the billet from being oxidized by oxygen in the air during the furnace discharge process. At the same time, the melting point of nickel and iron is higher than the heating temperature of steel austenite and will not melt.
  • the manganese-based coated steel sheet in this embodiment is placed in a heating furnace and heated to 860-950°C. After the temperature of the manganese-based coated steel sheet reaches 860-950°C, it is kept for 0-10 minutes.
  • the steel plate is austenitized, and the content of oxygen in the heating furnace is less than 0.02% in terms of mass%.
  • the above-mentioned manganese-based plated steel sheet after heating and/or heat preservation is placed in a mold to form a thermoformed product.
  • Heating in a furnace with an oxygen content of less than 0.02% can prevent the manganese-based coating from being oxidized.
  • the heating temperature of the steel plate is preferably not more than 900°C. Since the manganese-based coating on the surface of the steel plate will not melt when the steel plate is heated to this temperature, the heating rate of the steel plate in the heating furnace can be unrestricted. Under the premise of maintaining uniform temperature throughout the steel plate blank, The heating rate can be as fast as possible. In order to enhance the phosphating effect before electrophoresis and the durability of electrophoretic paint, it is possible to increase the holding time during austenitizing heating to obtain sufficient iron-manganese alloying.
  • the heating furnace in this embodiment may be a vacuum heating furnace with a vacuum degree of 0.01-100 Pa, or a protective atmosphere furnace, and the protective atmosphere furnace may be a nitrogen atmosphere furnace.
  • the oxygen content in the heating furnace is less than 0.002% in terms of mass%.
  • the temperature of the manganese-based coated steel sheet after pre-cooling is between 600 and 860°C, preferably, the manganese-based coated steel sheet is pre-cooled
  • the temperature is between 750 and 800°C, which will not cause a significant decrease in the forming performance of the steel sheet.
  • the austenitized manganese-based coated steel sheet is pre-cooled before being discharged. As the temperature of the steel sheet is reduced, the rate of oxidation reaction between the manganese-based coating layer and oxygen in the air can be greatly reduced. , Can reduce the steel plate being oxidized by oxygen in the air.
  • the specific pre-cooling method may include direct blowing of low-temperature nitrogen on the steel plate to quickly cool down the temperature.
  • the manganese-based plated steel sheet can be placed in a protective atmosphere and sent into the mold, and the mold can also be set in a protective atmosphere.
  • sexual atmosphere environment That is to say, the manganese-based plated steel sheet is sent into the mold set in the protective atmosphere under the protection of the protective atmosphere after being out of the furnace, and the oxygen content in the protective atmosphere is less than 3% in terms of mass%.
  • the temperature of the manganese-plated steel sheet at the moment of mold closing is greater than 550°C to ensure the forming performance of the steel sheet.
  • the hot formed product prepared by the method in this embodiment and the manganese-based plated steel sheet because in the high-temperature heating process of hot forming, the manganese element in the manganese-based coating layer diffuses into the steel plate matrix to form a room temperature austenite structure,
  • the low temperature thermal conductivity of the room temperature austenite structure is much lower than that of the steel sheet itself, which is equivalent to forming a poor thermal conductor on the surface of the steel sheet in the temperature range below 250°C.
  • the coating layer on the surface of the steel plate includes two structures, one is the ⁇ -phase iron-manganese solid solution alloy layer covering the surface of the steel plate, and the other is the ⁇ -phase iron-manganese solid solution alloy layer covering the surface of the steel plate.
  • the thickness of the ⁇ -phase ferromanganese solid solution alloy layer is not less than 1 ⁇ m, the thickness of the ⁇ -phase ferromanganese solid solution alloy layer is between 5 and 15 ⁇ m, and the total thickness of the ⁇ -phase ferromanganese solid solution alloy layer and the ⁇ -phase ferromanganese solid solution alloy layer It is between 6 and 20 ⁇ m, preferably, the thickness of the ⁇ -phase iron-manganese solid solution alloy layer is between 1 and 3 ⁇ m. Both the ⁇ -phase ferromanganese solid solution alloy layer and the ⁇ -phase ferromanganese solid solution alloy layer can make the coating layer on the surface of the product have good toughness and plasticity. Therefore, the steel plate and the coating layer on the surface of the product have good cold bending properties. .
  • the iron and manganese-based coating layers in the steel sheet diffuse each other to form a solid solution alloy. It does not form brittle intermetallic compounds. Therefore, there are no cracks in the steel plate and the coating layer of the hot formed product, and the structure of the coating layer is compact, so that the hot formed product has excellent corrosion resistance.
  • the manganese-based coating is an anodic coating, which can provide electrochemical protection.
  • the manganese-based coating has a stronger self-passivation ability after being corroded, and the corrosion current is higher than that of the zinc-based coating.
  • the coating should be small. Therefore, the corrosion resistance of the thermoformed product during service is further improved.
  • the above solid solution alloy can make the steel plate and the manganese coating layer have excellent bonding force.
  • the 100 grid test and the thermal shock test are carried out on the hot formed product. The experimental results show that the manganese coating layer on the steel plate has not fallen off, indicating The manganese-based coating has good adhesion to the steel plate.
  • the thermoformed product in this embodiment has good laser welding performance and spot welding performance.
  • the reflectivity of the manganese-based coating is not high; when the steel plate with aluminum-silicon coating is laser tailored, if the aluminum-silicon on the surface of the steel plate is not If the coating is removed, the high-reflectivity aluminum-silicon coating will make the laser generator easy to burn out during the laser tailor welding process, and aluminum will form Fe-Al alloy with the iron in the steel plate that makes the tailor welded seam brittle Phase; and the low-reflectivity manganese-based coating will not cause the laser generator to be burnt out during the tailor welding of the steel plate.
  • the manganese plating layer has a higher resistivity, which effectively reduces the spot welding current and increases the life of the spot welding electrode.
  • thermoformed product in this embodiment is carried out in an environment with very low oxygen content due to the austenitizing heating of the blank and the transfer to the mold, even during the mold clamping process, in an environment with a very low oxygen content.
  • the amount of oxidation during heating is very small.
  • the heated billet has a good appearance such as low surface roughness and smooth surface.
  • the manganese-based coating layer of the billet is dense, and the thickness of the coating layer diffusion is small, which is beneficial to improve The forming properties of the blank.
  • the manganese-based plating layer on the surface of the steel sheet has a good bonding force with the electrophoretic layer.
  • the following uses four cases and a comparative example to further illustrate the manganese-based plated steel sheet and its hot forming method and hot forming product of this embodiment.
  • a steel plate with a thickness of 1.4mm is hot rolled, cold rolled, and manganese electroplated in sequence.
  • the steel plate contains C: 0.22%, Mn: 1.2%, Al: 0.01%, and Ti: 0.03% in terms of mass%.
  • the adhesion amount of the manganese coating on the steel plate is 40g/m2 (converted to a thickness of about 5 ⁇ m), and the manganese coating is calculated as mass% , Manganese content ⁇ 99%.
  • the steel coil with the manganese coating is blanked to obtain a blank.
  • the blanking method can be cold stamping with a die or laser cutting.
  • the above-mentioned billet is placed in a vacuum heating furnace controlled to have an oxygen content of 0.0002% or less and heated for 220 seconds to 900° C. to austenitize the steel sheet and simultaneously alloy the steel sheet and the manganese coating.
  • nitrogen gas was introduced into the vacuum heating furnace to pre-cool the heated billet for 3 seconds, and the surface temperature of the billet after the pre-cooling was 750°C.
  • the pre-cooled blank is taken out from the vacuum heating furnace, and is sent into the mold for forming under a nitrogen atmosphere to obtain a formed product.
  • thermoformed product is processed by laser cutting and shot blasting to make ultra-high-strength steel auto parts.
  • the steel plate includes C: 0.21%, Mn: 1.5%, Al: 0.02%, Cr: 0.3%, Mo: 0.1%, Cu: 0.1%, Ni: 0.1%, B: 0.004% , The balance is Fe.
  • the above blank is electroplated with manganese, the adhesion amount of the manganese coating on the steel plate is 80g/m2 (converted to a thickness of about 10 ⁇ m), and the manganese content in the manganese coating is ⁇ 99% in terms of mass%.
  • electroplating iron is performed on the blank obtained in the previous step, so that the surface of the manganese plating layer is covered with an iron plating layer with a thickness of 0.5 ⁇ m, and the iron content in the nickel plating layer is ⁇ 99% in terms of mass %.
  • the billet obtained in the above steps is placed in a protective atmosphere furnace and heated for 240 seconds to 900° C., and the nitrogen content in the protective atmosphere furnace is 99.99%.
  • the heated blank is taken out of the heating furnace and sent into the mold under a nitrogen atmosphere to form a molded product.
  • thermoformed product is processed by laser cutting and shot blasting to make ultra-high-strength steel auto parts.
  • the steel plate contains: C: 0.21%, Mn: 1.5%, Al: 0.02%, Cr: 0.3%, Mo: 0.1%, Cu: 0.1%, Ni: 0.1%, B: 0.004%, the balance is Fe; the adhesion amount of the manganese coating on the steel plate is 90g/m2 (converted to a thickness of about 12 ⁇ m) , In terms of mass%, its manganese content is ⁇ 99%.
  • the two steel coils with manganese coating are blanked to obtain two blanks with different thicknesses.
  • the pre-cooled blank is taken out from the vacuum heating furnace, and is sent into the mold under a nitrogen atmosphere to form a molded product.
  • thermoformed product is processed by laser cutting and shot blasting to make ultra-high-strength steel auto parts.
  • a steel plate with a thickness of 1.4mm is hot rolled, cold rolled, and manganese electroplated in sequence.
  • the steel plate contains C: 0.22%, Mn: 1.2%, Al: 0.01%, and Ti: 0.03% in terms of mass%. , Nb: 0.02%, V: 0.05%, B: 0.003%, the balance is Fe; the adhesion amount of the manganese coating on the steel plate is 40g/m2 (converted to a thickness of about 5 ⁇ m), and the manganese coating is based on the mass %, the manganese content is ⁇ 99%.
  • the steel coil with the manganese coating is blanked to obtain a blank.
  • the blanking method can be cold stamping with a die or laser cutting.
  • the above-mentioned billet is placed in a vacuum heating furnace controlled to have an oxygen content of 0.0002% or less and heated for 360 seconds to 900° C. to austenitize the steel sheet and simultaneously alloy the steel sheet and the manganese coating.
  • nitrogen gas was introduced into the vacuum heating furnace to pre-cool the heated billet for 3 seconds, and the surface temperature of the billet after the pre-cooling was 750°C.
  • the pre-cooled blank is taken out from the vacuum heating furnace, and is sent into the mold for forming under a nitrogen atmosphere to obtain a formed product.
  • thermoformed product is processed by laser cutting and shot blasting to make ultra-high-strength steel auto parts.
  • the AS60/60 aluminum-silicon coated steel coil with a thickness of 1.5mm is blanked to obtain a blank, wherein the adhesion amount of the aluminum-silicon coating on the surface of the aluminum-silicon coated steel is 75g/m2 (converted to a thickness of about 25 ⁇ m).
  • the above-mentioned billet was placed in a protective atmosphere furnace and heated for 300 seconds to 930°C.
  • the heated blank is placed in a mold for forming to obtain a product.
  • the product is laser cut and vented to make ultra-high-strength steel auto parts.
  • the thermoforming After that, the more ⁇ -phase ferromanganese solid solution and ⁇ -phase ferromanganese solid solution alloy in the coating layer, because the ⁇ -phase ferromanganese solid solution and ⁇ -phase ferromanganese solid solution alloy have good toughness and plasticity, it is beneficial to improve the three-point bending of the product performance.
  • the surface roughness of the thermoformed product in this embodiment is less than 1.3 ⁇ m, which meets the requirements of the automotive industry for the surface roughness of coated parts (currently, the automotive industry has The surface roughness of the layer parts is required to be between 0.8 and 1.3 ⁇ m).
  • the salt spray test was conducted on the above case 2 and the comparative example 1.
  • the test results showed that the comparative example 1 had obvious corrosion (as shown in Figure 4, the surface has a lot of rust), and the case 2 At the 120th hour of the test, there was no corrosion (as shown in Figure 5, there was almost no rust on the surface). It can be seen that the corrosion resistance of the manganese-based coated steel sheet of this embodiment after hot forming far exceeds that of the hot formed product of the aluminum-silicon coated steel sheet.
  • thermoformed product in the above case 1 the adhesion amount of the manganese-based coating layer is 40g/m2, converted to a thickness of about 5 ⁇ m
  • the content of iron, manganese, carbon, and oxygen at the location, and the measurement results are shown in Table 3 below.
  • SEM Sccanning Electron Microscope, Scanning Electron Microscope
  • XRD X-ray Diffraction
  • the plating layer on the surface of Case 1 has a total thickness of about 5.5 ⁇ m, which is mainly divided into three structural layers.
  • the layer closest to the iron matrix of the steel plate is ⁇ + ⁇ phase ferromanganese structure with a thickness of about 1.233 ⁇ m; the outermost layer is manganese oxide with a thickness of about 2.666 ⁇ m; the middle layer is ⁇ phase ferromanganese
  • the thickness of the solid solution is about 1.667 ⁇ m.
  • the ⁇ -phase ferromanganese solid solution of the intermediate layer has a manganese content of about 50%, which has good corrosion resistance and can effectively protect the steel body matrix.
  • the innermost ⁇ + ⁇ phase iron-manganese austenite structure has good toughness and can improve the impact energy absorption effect of the parts. Therefore, the average value of the three-point bending of the 5-8um manganese plating layer is 78.3°. Therefore, the manganese plating layer of about 5-8um can be used in occasions where anti-corrosion requirements are not high.
  • the plating layer on the surface of Case 3 has a thickness of about 12 ⁇ m, which is mainly divided into three structural layers.
  • the layer closest to the iron matrix of the steel plate is ⁇ + ⁇ phase iron-manganese structure with a thickness of about 3 ⁇ m; the outermost layer is manganese oxide with a thickness of about 2 ⁇ 3 ⁇ m; the middle layer is ⁇ phase
  • the thickness of ferromanganese solid solution is about 5-8 ⁇ m.
  • the thickness of the ⁇ -phase ferromanganese solid solution in Case 3 is as high as 5-8 ⁇ m, it has an excellent sacrificial anode protection effect, and the effect of Case 3 is significantly better than that of Case 1.
  • the thickness of the ⁇ + ⁇ phase iron-manganese structure in Case 3 is also large, especially the thickness of the ⁇ -phase iron-manganese structure is greater than that of the ⁇ -phase iron-manganese structure in Case 1, therefore, the three-point bending angle of Case 3 is obvious Three-point bending angle better than Case 1.
  • the electrode potential is basically the same as that of the steel substrate.
  • the thin coating can save costs and improve the three-point bending performance and welding performance.

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Abstract

本发明公开了一种锰系镀覆钢板及其热成型方法和热成型产品。所述锰系镀覆钢板包括钢板和设置于所述钢板的两面的锰系镀覆层，其中，所述钢板上的锰系镀覆层的附着量在40g/㎡～110g/㎡之间，所述锰系镀覆层中以质量％计，Mn的含量大于或等于80％。本发明所采用的方案，具有提高钢板表面耐腐蚀性、提高钢板的三点弯曲性能、提高钢板在热成型时的升温速率等优点。

Description

一种锰系镀覆钢板及其热成型方法和热成型产品
交叉参考相关引用
本申请要求2020年6月10日提交的申请号为2020105227568、名称为“一种锰系镀覆钢板及其热成型方法和热成型产品”的中国专利申请的优先权，上述申请参考并入本文。
技术领域
本发明涉及了热冲压成型技术领域，具体的是一种锰系镀覆钢板及其热成型方法和热成型产品。
背景技术
为了提高热成型用钢在成型前的奥氏体化加热过程中的抗氧化性能和热成型后产品在服役期间的耐腐蚀性能，目前常采用铝硅涂层钢板(如专利CN 108588612A一种锌系镀覆钢板或钢带的热冲压成型方法)或者锌涂层钢板(如专利CN107127238A热冲压成型用锌镁镀层钢板及其制造和热冲压方法)来作为热成型产品的坯料，并将上述两种材质的坯料放置在空气气氛环境下进行奥氏体化加热后再放入模具内冲压成为热成型产品。
虽然铝硅涂层钢板在空气环境下加热可以有效的防止其铁基体在加热时氧化，但是也有如下缺点：
1.由于铝的熔点只有680℃左右，铝硅涂层钢板在奥氏体化加热(通常温度高于860℃)时会产生涂层熔化，熔化的涂层会污染加热炉的炉辊和冲压模具，导致炉辊和模具的寿命下降。
2.如图1所示，为了减少铝硅涂层的熔化，在加热时需要限制加热速率以留出铝硅涂层与基体铁的扩散时间来获得高熔点的铁铝金属间化合物。另外，为了减少铝涂层对热成型产品后序焊接性能的不良影响，需要在加热时延长保温时间使得铝硅涂层与基体铁充分的扩散以便在涂层中生成铁含量丰富的铁铝金属间化合物。这些措施都造成加热效率的下降和能耗的增加。
3.铝硅涂层在加热过程中生成的脆性金属间化合物在冷却后产生大量的裂纹，这些裂纹导致铝硅涂层热成型产品在服役期间的耐腐蚀性能下降。
4.由于铝具有高导热性及脆性、铁铝金属间化合物夹杂，这些加速了焊接裂纹的产生。因此，铝硅涂层恶化了铝硅涂层钢板和铝硅涂层热成型产品的焊接性能。
5.铝硅涂层具有良好的低温导热性，使得热成型淬火冷却速度过高，基体马氏体组织来不及进行自回火，导致铝硅涂层热成型产品具有较差的冷弯性能(指金属材料在常温下能承受弯曲而不破裂的性能)。铝硅涂层中大量的裂纹、基体脱碳层的减少(基体表层受涂层保护几乎无高温氧化和脱碳)和基体表面层碳含量增加(基体表层的铁离开基体扩散进入涂层，基体表层碳含量相对增加)也都是其热成型产品冷弯性能不良的重要原因(远不如无涂层钢热成形产品)。
6.铝硅涂层在热成形加热和冷却过程中经历了熔化和凝固，并且产生了脆性的金属间化合物，这些都导致涂层表面的毛化，使得涂层表面的粗糙度远高于热成形加热前的涂层表面。涂层表面较高的摩擦系数不利于冲压过程中的材料流动，从而降低钢板成形性能。
而锌涂层钢板除了具有防止热成型钢的铁基体在空气中奥氏体化加热时发生氧化的性能，还具有牺牲阳极保护功能从而提高了锌涂层钢板热成形产品在服役期间的耐腐蚀性能。但是，锌涂层钢板除了具有前述所列的所有铝硅涂层的缺点以外，还会因其液态金属脆性导致基体裂纹。因此，锌涂层钢板大多应用在间接热成形制造方法。
除了前述涂层应用在热成型钢板之外，还有文献提到采用镍合金涂层，但由于成本问题很少在工业中应用。
发明内容
为了克服现有技术中的缺陷，本发明实施例提供了一种锰系镀覆钢板及其热成型方法和热成型产品，其用于解决上述问题中的至少一种。
本申请实施例公开了：一种锰系镀覆钢板，包括钢板和设置于所述钢板的两面的锰系镀覆层，其中，所述钢板上的锰系镀覆层的附着量在40g/㎡～110g/㎡之间，所述锰系镀覆层中以质量％计，Mn的含量大于或等于80％。
具体的，所述钢板上的锰系镀覆层的附着量在70g/㎡～100g/㎡之间。
具体的，所述锰系镀覆层包括纯锰、锰铁合金、锰锌合金、锰铝合金、锰镍合金、锰锌镍合金、锰铝镍合金、锰铬合金、锰锌铬合金或锰铝铬合金中的一种或多种。
具体的，所述钢板以质量％计，其中，各组分含量为C:0.1％～0.4％、Mn:0.5％～2.0％、Al:0.005％～0.1％、B:0.001％～0.010％。
具体的，所述钢板还包括，以质量％计，Ti:0.01％～0.20％，和/或Nb:0.01％～0.20％，和/或V:0.1％～0.5％中的一种或多种。
具体的，所述钢板还包括，以质量％计，Cr:0.1％～0.5％，和/或Mo:0.1％～0.5％，和/或Cu:0.1％～0.5％，和/或Ni:0.1％～0.5％中的一种或多种。
具体的，所述锰系镀覆层通过电镀工艺附着在所述钢板上。
具体的，两个所述锰系镀覆层远离所述钢板的一面还分别设有镍镀层或铁镀层，所述镍镀层或铁镀层的厚度小于1μm。
本申请实施例还公开了：一种如本实施例所述的锰系镀覆钢板的热成型方法，包括以下步骤：
将所述锰系镀覆钢板放置于加热炉中加热至860～950℃，使所述锰系镀覆钢板中的钢板奥氏体化，所述加热炉中以质量％计，氧的含量小于0.02％；
将加热至860～950℃后的所述锰系镀覆钢板放入模具中成型，获得热成型产品。
具体的，所述加热炉为真空加热炉。
具体的，所述奥氏体保温时间在0～10分钟之间。
具体的，在所述锰系镀覆钢板加热后且出炉之前，向所述真空加热炉内通入纯度为99.999％以上的氮气以对所述锰系镀覆钢板进行预冷1～10秒，预冷后的所述锰系镀覆钢板的温度介于600～860℃之间。
具体的，所述锰系镀覆钢板的预冷时间在1～3秒之间。
具体的，预冷后的所述锰系镀覆钢板的温度介于750～800℃之间。
具体的，所述加热炉为保护性气氛炉。
具体的，所述加热炉中以质量％计，氧的含量小于0.002％。
具体的，所述锰系镀覆钢板在保护性气氛保护下被送入所述模具中，所述模具设置在所述保护性气氛中，所述保护性气氛中以质量％计，氧的含量小于3％。
具体的，所述锰系镀覆钢板在所述模具合模瞬间的温度大于550℃。
本申请实施例还公开了：一种热成型产品，其采用本实施例中的锰系镀覆钢板和热成型方法制备。
具体的，所述热成型产品的锰系镀覆层包括附着在钢板表面的γ相铁锰固溶体合金层和附着在所述γ相铁锰固溶体层远离所述钢板的一面的β相锰铁固溶体合金层。
具体的，所述γ相铁锰固溶体合金层的厚度不小于1μm，所述β相锰铁固溶体合金层的厚度介于5～15μm之间，所述γ相铁锰固溶体合金层和所述β相锰铁固溶体合金层的总厚度介于6～20μm之间。
本发明至少具有如下有益效果：
1.锰系镀覆层中的Mn含量大于或等于80％。Mn合金的熔点约为1200℃，远高于钢板的奥氏体化温度(通常低于950℃)，因此，锰系镀覆钢板在热成型工艺的加热过程中，其锰系镀覆层不会熔化，因而不会污染加热炉炉辊，也不会在模具中成型时污染模具。另外，由于锰系镀覆层不会熔化，可以不用提供额外的低温加热时间来使Mn与钢板中的Fe发生合金化。因此，如图2所示，在确保钢板受热均匀的情况下，钢板的加热速率可以尽可能的快，钢板在整个加热过程中的速率可以保持不变，以提高生产效率、降低能耗。
2.采用本实施例中的方法和锰系镀覆钢板所制备的热成型产品，由于在热成型的高温加热过程中，锰系镀覆层中的锰元素扩散进入钢板基体形成室温奥氏体组织，该室温奥氏体组织的低温导热性能远低于钢板本身，相当于在250℃以下的温度区间内，在钢板表面形成热的不良导体。在热成型淬火冷却到马氏体完体转变温度Mf点时，上述室温奥氏体组织延迟了钢板被模具的进一步快速冷却，使得钢板的淬火马氏体可以充分发生自回火，提高了产品的韧性和冷弯性能。
3.本实施例的热成型产品，其钢板表面的镀覆层包括两种结构，一种是覆盖在钢板表面的γ相铁锰固溶体合金层，另一种是覆盖在γ相铁锰固溶体合金层远离钢板的一面上的β相锰铁固溶体合金层。其中，γ相铁锰固溶体合金层的厚度不小于1μm，β相锰铁固溶体合金层的厚度介于5～15μm之间，γ相铁锰固溶体合金层和β相锰铁固溶体合金层的总厚度介于6～20μm之间，较佳的，γ相铁锰固溶体合金层的厚度介于1～3μm之间。γ相铁锰固溶体合金层和β相锰铁固溶体合金层均可以使得产品表面的镀覆层具有良好的韧性和塑性，因此，产品的钢板及其表面的镀覆层均具有良好的冷弯性能。
4.在采用本实施例中的方法和锰系镀覆钢板进行热成型时，由于Fe和Mn两种元素的固溶度很高，钢板中的铁和锰系镀覆层相互扩散时形成固溶体合金而非形成脆性金属间化合物，因此，热成型产品的钢板内部和镀覆层内部均没有裂纹，且镀覆层的结构致密，从而使得热成型产品具有优异的耐腐蚀性能。另外，对于钢板内的大量Fe而言，该锰系镀覆层为阳极性镀层，可以提供电化学保护功能，而且，锰系镀覆层受腐蚀后自钝化能力强，腐蚀电流比锌系涂层要小，因此，本实施例的热成型产品在服役期间的耐腐蚀性能得到进一步提升。
5.本实施例中的热成型产品具有良好的激光焊接性能和点焊性能。
6.本实施例中的热成型产品，由于坯料的奥氏体化加热和转运至模具的过程中，甚至在模具合模的过程中，均在含氧量很低的环境下进行，因此，坯料在加热过程中的氧化量非常微小，加热后的坯料具有表面粗糙度低、表面平滑等良好的外观，且加热后坯料的锰系镀覆层致密，镀覆层扩散的厚度较小，有利于提高坯料的成型性能。
为让本发明的上述和其他目的、特征和优点能更明显易懂，下文特举较佳实施例，并配合所附图式，作详细说明如下。
附图说明
为了更清楚地说明本发明实施例或现有技术中的技术方案，下面将对实施例或现有技术描述中所需要使用的附图作简单地介绍，显而易见地，下面描述中的附图仅仅是本 发明的一些实施例，对于本领域普通技术人员来讲，在不付出创造性劳动的前提下，还可以根据这些附图获得其他的附图。
图1是现有技术中具有铝硅涂层的钢板在奥氏体化加热时的升温曲线图；
图2是本发明实施例中所述锰系镀覆钢板在奥氏体化加热时的升温曲线图；
图3是采用本发明实施例中所述锰系镀覆钢板拼焊后的拼焊板的拉伸试验结果示意图；
图4是铝硅涂层钢板所制的热成型产品在盐雾试验6小时后其表面变化的示意图；
图5是本实施例中的热成型产品在盐雾试验120小时后其表面变化的示意图；
图6是本实施例中的案例1中热成型产品的SEM图；
图7是本实施例中的案例1中热成型产品的XRD图；
图8是本实施例中的案例3中热成型产品的SEM图；
图9是本实施例中的案例3中热成型产品的XRD图。
具体实施方式
下面将结合本发明实施例中的附图，对本发明实施例中的技术方案进行清楚、完整地描述，显然，所描述的实施例仅仅是本发明一部分实施例，而不是全部的实施例。基于本发明中的实施例，本领域普通技术人员在没有做出创造性劳动前提下所获得的所有其他实施例，都属于本发明保护的范围。
本实施例中的锰系镀覆钢板，包括钢板和设置于钢板的两面的锰系镀覆层，也就是说，在本实施例中，钢板的正面和反面均具有锰系镀覆层。其中，锰系镀覆层在钢板上的附着量在40g/㎡～110g/㎡(换算为厚度是5～15mm之间)之间，也即，每平方米的钢板上附着有40～110g的锰系镀覆层，较佳的，锰系镀覆层在钢板上的附着量在70g/㎡～100g/㎡(换算为厚度是9～14mm)之间。以质量％计，锰系镀覆层中的Mn含量大于或等于80％。Mn合金的熔点约为1200℃，远高于钢板的奥氏体化温度(通常低于950℃)，因此，锰系镀覆钢板在热成型工艺的加热过程中，其锰系镀覆层不会熔化，因而不会污染加热炉炉辊，也不会在模具中成型时污染模具。另外，由于锰系镀覆层不会熔化，可以不用提供额外的低温加热时间来使Mn与钢板中的Fe发生合金化。因此，如图2所示，在确保钢板受热均匀的情况下，钢板的加热速率可以尽可能的快，钢板在整个加热过程中的速率可以保持不变，以提高生产效率、降低能耗。
经过反复的实验验证，由于在热成型过程中，锰系镀覆层难免有一部分被氧化，因此，当钢板上的锰系镀覆层的附着量过少(不足40g/㎡)时，热成型后的热成型产品中，锰系镀覆层难以对钢板形成足够的耐腐蚀保护；而当钢板上的锰系镀覆层的附着量过多(超过110g/㎡)时，热成型后的热成型产品的焊接性能会有所下降，同时，附着量过多还会造成不必要的成本增加。因此，本实施例中的具有附着量为40g/㎡～110g/㎡的 锰系镀覆层的钢板的综合性能较佳。
本实施例中的锰系镀覆层可以包括纯锰、锰铁合金、锰锌合金、锰铝合金、锰镍合金、锰锌镍合金、锰铝镍合金、锰铬合金、锰锌铬合金或锰铝铬合金中的一种或多种。换句话说，用于形成本实施例的锰系镀覆层的原材料可以包括纯锰、锰铁合金、锰锌合金、锰铝合金、锰镍合金、锰锌镍合金、锰铝镍合金、锰铬合金、锰锌铬合金或锰铝铬合金中的一种或多种。较佳的，当锰系镀覆层中含有铝时，铝的质量分数小于0.5％，避免镀覆层中的铝与钢板中的铁反应而形成脆性的铁铝合金；而锰系镀覆层中的低熔点合金的含量优选控制在5％以下，以免在高温加热过程中，低熔点合金熔化会对加热炉的炉辊造成污染。
具体来说，本实施例中的钢板以质量％计，可以包括C:0.1％～0.4％、Mn:0.5％～2.0％、Al:0.005％～0.1％、B:0.001％～0.010％，余量为Fe。其中，C为提高钢板的淬火性并且主要决定淬火后强度的非常重要的元素。当C含量不足0.1％时，其效果不充分，因此，C含量设为0.1％以上；另一方面，当C含量超过0.4％时，淬火后的韧性劣化显著而且焊接性能不良。因此，C含量设为0.4％以下，优选为0.3％以下，也即，C含量优选为0.1％～0.3％。Mn为用于提高钢板的淬火性、并且稳定地确保淬火后强度的非常有效之元素。当Mn含量不足0.5％时，其效果不充分，因此，Mn含量设为0.5％以上，优选为1％以上；另一方面，当Mn含量超过2.0％时，不仅其效果饱和，相反，还存在淬火后稳定的强度确保变得困难的情况。因此，Mn含量设为2.0％以下，优选为1.5％以下，也即，Mn含量优选为1％～1.5％。A1具有将钢脱氧、使钢材健全化的作用。A1含量不足0.005％时，难以起到上述作用，因此，Al含量设为0.005％以上；Al含量超过0.1％时，基于上述作用的效果饱和，在成本上不利。因此，A1含量设为0.1％以下。B是可以提高钢板淬透性的元素，在钢板热成型过程中，防止钢板中的奥氏体向铁素体转变而导致钢板的强度降低，B含量设为0.001％～0.010％，优选为0.001％～0.008％。
较佳的，以钢板的质量％计，钢板还可以包含Ti:0.01％～0.20％、Nb:0.01％～0.20％、V:0.1％～0.5％中的一种或多种。具体来说，钢板还可以包括Ti、Nb、V中的一种或多种，当钢板中含有Ti时，钢板中Ti的含量在0.01％～0.20％之间；当钢板中含有Nb时，钢板中Nb的含量在0.01％～0.20％之间；当钢板中含有V时，其在钢板中的含量在0.1％～0.5％之间。Ti、Nb和V可以在奥氏体化过程中析出一定的复合碳化物，细化原奥氏体晶粒，增加材料强度。然而，当Ti、Nb的总含量超过0.20％时、或者V的含量超过1.0％时，基于上述作用的效果饱和，在成本上是不利的。因此，Ti、Nb的总含量设为0.20％以下， V的含量设为1.0％以下。优选Ti、Nb的含量分别为0.15％以下，V为0.5％以下。为了更可靠地得到上述效果，优选将Ti、Nb的含量设为0.01％以上、将V的含量设为0.1％以上。
进一步的，以钢板的质量％计，钢板还可以包括Cr:0.1％～0.5％、Mo:0.1％～0.5％、Cu:0.1％～0.5％、Ni:0.1％～0.5％中的一种或多种。具体来说，钢板还可以包括Cr、Mo、Cu、Ni中的一种或多种，其中，当钢板中含有Cr时，钢板中的Cr含量为0.1％～0.5％；当钢板中含有Mo时，钢板中Mo含量为0.1％～0.5％；当钢板中含有Cu时，钢板中Cu含量为0.1％～0.5％；当钢板中含有Ni时，钢板中Ni含量为0.1％～0.5％。Cr、Mo、Cu、Ni可以提高钢板的淬火性并且稳定地确保淬火后强度。
本实施例中的锰系镀覆层可以通过电镀工艺的方式附着在钢板上，电镀方式是冷镀(在常温下进行)，因此可以避免在电镀过程中锰被氧化，同时，电镀的方式可以具有较高的效率。
本实施例中的锰系镀覆钢板，其锰系镀覆层外还可以设有厚度小于1μm的镍镀层或铁镀层，也即，可以在锰系镀覆层远离钢板的一面上设有厚度小于1μm的镍镀层或铁镀层。该镍镀层或铁镀层可以防止坯料在出炉过程中其表面的锰被空气中的氧所氧化，同时，镍和铁的熔点比钢板奥氏体加热温度高，不会熔化。
本实施例中的锰系镀覆钢板的热成型方法包括以下步骤：
首先，将本实施例中的锰系镀覆钢板放置于加热炉中加热至860～950℃，待锰系镀覆钢板的温度达到860～950℃后对其进行保温0～10分钟之间，使其中的钢板奥氏体化，其中，加热炉中以质量％计，氧的含量小于0.02％。
接着，将上述经过加热和/或保温后的锰系镀覆钢板放入模具中成型，使之形成热成型产品。
在含氧量小于0.02％的加热炉中加热，可以避免锰系镀覆层被氧化。
为了避免钢板在奥氏体化加热过程中其晶粒粗大，同时也为了避免浪费能耗，钢板加热的温度优选不超过900℃。由于当钢板被加热至该温度时，其表面的锰系镀覆层不会发生熔化，因此，钢板在加热炉中的升温速率可以不受限制，在保持钢板坯料各处温度均匀的前提下，升温速率可以越快越好。为了增强电泳前的磷化效果及电泳漆的耐久性，可以采用增加奥氏体化加热时的保温时间以获得充分的铁锰合金化。
本实施例中的加热炉可以是其真空度为0.01-100pa之间的真空加热炉，也可以是保护性气氛炉，该保护性气氛炉可以是氮气气氛炉。较佳的，加热炉中以质量％计，氧的含 量小于0.002％。当加热炉为真空加热炉时，在锰系镀覆钢板加热至奥氏体化温度后且出炉之前，可以向真空加热炉中通入纯度为99.999％以上的氮气以对锰系镀覆钢板进行预冷1～10秒，优选预冷时间为1～3秒，预冷后的锰系镀覆钢板的温度介于600～860℃之间，较佳的，锰系镀覆钢板预冷后的温度介于750～800℃之间，该温度不会导致钢板的成型性能明显下降。采用上述方案，奥氏体化的锰系镀覆钢板经过预冷后再出炉，由于钢板的温度有所降低，可以大大降低了锰系镀覆层与空气中的氧气发生氧化反应的速率，因此，可以减少了钢板被空气中的氧气氧化。具体的预冷方法可以包括采用低温氮气对钢板进行直吹以快速降温。
进一步的，为了避免锰系镀覆钢板在出炉后转运至模具中的这一过程被氧化，可以将锰系镀覆钢板放在保护性气氛环境中被送入模具内，模具也可以设置在保护性气氛环境中。也就是说，锰系镀覆钢板出炉后在保护性气氛的保护下被送入设置在该保护性气氛中的模具内，以质量％计，该保护性气氛中的氧含量小于3％。
锰系镀覆钢板在模具合模瞬间的温度大于550℃，以确保钢板的成型性能。
采用本实施例中的方法和锰系镀覆钢板所制备的热成型产品，由于在热成型的高温加热过程中，锰系镀覆层中的锰元素扩散进入钢板基体形成室温奥氏体组织，该室温奥氏体组织的低温导热性能远低于钢板本身，相当于在250℃以下的温度区间内，在钢板表面形成热的不良导体。在热成型淬火冷却到马氏体完体转变温度Mf点时，上述室温奥氏体组织延迟了钢板被模具的进一步快速冷却，使得钢板的淬火马氏体可以充分发生自回火，提高了产品的韧性和冷弯性能。另外，本实施例的热成型产品，其钢板表面的镀覆层包括两种结构，一种是覆盖在钢板表面的γ相铁锰固溶体合金层，另一种是覆盖在γ相铁锰固溶体合金层远离钢板的一面上的β相锰铁固溶体合金层。其中，γ相铁锰固溶体合金层的厚度不小于1μm，β相锰铁固溶体合金层的厚度介于5～15μm之间，γ相铁锰固溶体合金层和β相锰铁固溶体合金层的总厚度介于6～20μm之间，较佳的，γ相铁锰固溶体合金层的厚度介于1～3μm之间。γ相铁锰固溶体合金层和β相锰铁固溶体合金层均可以使得产品表面的镀覆层具有良好的韧性和塑性，因此，产品的钢板及其表面的镀覆层均具有良好的冷弯性能。
在采用本实施例中的方法和锰系镀覆钢板进行热成型时，由于Fe和Mn两种元素的固溶度很高，钢板中的铁和锰系镀覆层相互扩散时形成固溶体合金而非形成脆性金属间化合物，因此，热成型产品的钢板内部和镀覆层内部均没有裂纹，且镀覆层的结构致密，从而使得热成型产品具有优异的耐腐蚀性能。另外，对于钢板内的大量Fe而言，该锰系 镀覆层为阳极性镀层，可以提供电化学保护功能，而且，锰系镀覆层受腐蚀后自钝化能力强，腐蚀电流比锌系涂层要小，因此，本实施例的热成型产品在服役期间的耐腐蚀性能得到进一步提升。上述固溶体合金可以使得钢板与锰系镀覆层具有极好的结合力，对热成型产品进行百格测试以及冷热冲击试验，实验结果显示，钢板上的锰系镀覆层并未脱落，表明锰系镀覆层与钢板的结合力良好。
本实施例中的热成型产品具有良好的激光焊接性能和点焊性能。关于其激光拼焊性能，与铝硅涂层的高反射率不同，锰系镀覆层的反射率不高；具有铝硅涂层的钢板在激光拼焊时，如不将钢板表面的铝硅涂层去除的话，高反射率的铝硅涂层会使得激光发生器在激光拼焊过程中容易烧坏，且铝会与钢板中的铁形成使拼焊焊缝易脆断的Fe-Al合金相；而低反射率的锰系镀覆层不会导致激光发生器在对钢板的拼焊过程中被烧坏。通过拉伸试验发现，具有锰系镀覆层的钢板在拼焊后受拉伸时，拼焊板的断裂处往往发生在母材上而非在焊缝处(如图3所示)。而关于其点焊性能，锰系镀覆层具有较高的电阻率，有效地减少了点焊电流，提高了点焊电极的寿命。
本实施例中的热成型产品，由于坯料的奥氏体化加热和转运至模具的过程中，甚至在模具合模的过程中，均在含氧量很低的环境下进行，因此，坯料在加热过程中的氧化量非常微小，加热后的坯料具有表面粗糙度低、表面平滑等良好的外观，且加热后坯料的锰系镀覆层致密，镀覆层扩散的厚度较小，有利于提高坯料的成型性能。另外，本实施例中的热成型产品经过电泳后，钢板表面的锰系镀覆层与电泳层的结合力良好。
以下采用四个案例和一个对比例对本实施例的锰系镀覆钢板及其热成型方法和热成型产品作进一步说明。
案例1
首先，对厚度为1.4mm的钢板依次进行热轧、冷轧、电镀锰，其中，钢板中以质量％计，包含：C:0.22％、Mn:1.2％、Al:0.01％、Ti:0.03％、Nb:0.02％、V:0.05、B:0.003，余量为Fe；锰镀层在钢板上的附着量为40g/㎡(换算为厚度约为5μm)，锰系镀覆层中以质量％计，锰含量≥99％。
接着，将具有锰镀层的钢卷进行落料以获得坯料，落料的方式可以是模具冷冲压，也可以是激光切割。
接着，将上述坯料放入氧含量控制在0.0002％以下的真空加热炉内加热220秒至900℃，使钢板发生奥氏体化，同时，钢板和锰镀层发生合金化。
接着，向真空加热炉内通入氮气以对加热完成的坯料进行预冷3秒钟，预冷后的坯 料表面温度为750℃。
接着，将预冷后的坯料从真空加热炉中取出，在氮气保护气氛下送入模具内成型，获得成型产品。
接着，将热成型产品经过激光切割和抛丸处理，制成超高强钢汽车零件。
案例2
首先，对厚度为1.6mm的钢板卷进行落料，以获得坯料。其中，以钢板的质量％计，钢板包括C：0.21％、Mn:1.5％、Al:0.02％、Cr：0.3％、Mo：0.1％、Cu:0.1％、Ni:0.1％、B:0.004％，余量为Fe。
接着，对上述坯料进行电镀锰处理，锰镀层在钢板上的附着量为80g/㎡(换算为厚度约为10μm)，以质量％计，锰镀层中的锰含量≥99％。
接着，对上一步骤所获得的坯料进行电镀铁处理，以使锰镀层的表面上覆盖一层厚度为0.5μm的铁镀层，以质量％计，镍镀层中的铁含量≥99％。
接着，将上述步骤获得的坯料放入保护性气氛炉内加热240秒至900℃，保护性气氛炉中氮气的含量为99.99％。
接着，将加热完成的坯料从加热炉中取出并在氮气保护气氛下送入模具内成型，获得成型产品。
接着，将热成型产品经过激光切割和抛丸处理，制成超高强钢汽车零件。
案例3
首先，对厚度分别为1.2mm和1.5mm的钢板依次进行热轧、冷轧、电镀锰，其中，钢板中以质量％计，包含：C：0.21％、Mn:1.5％、Al:0.02％、Cr：0.3％、Mo：0.1％、Cu:0.1％、Ni:0.1％、B:0.004％，余量为Fe；锰镀层在钢板上的附着量为90g/㎡(换算为厚度约为12μm)，以质量％计，其锰含量≥99％。
接着，将具有锰镀层的两个钢卷分别进行落料以获得两个厚度不同的坯料。
接着，将两个厚度不同的坯料进行激光拼焊。
接着，将拼焊后的坯料放入氧含量控制在0.0002％以下的真空加热炉内加热230秒至900℃。
接着，向真空加热炉内通入氮气以对加热完成的坯料进行预冷2秒钟，预冷后的坯料表面温度为800℃。
接着，将预冷后的坯料从真空加热炉中取出，在氮气保护气氛下送入模具内成型， 获得成型产品。
接着，将热成型产品经过激光切割和抛丸处理，制成超高强钢汽车零件。
案例4
首先，对厚度为1.4mm的钢板依次进行热轧、冷轧、电镀锰，其中，钢板中以质量％计，包含：C:0.22％、Mn:1.2％、Al:0.01％、Ti:0.03％、Nb:0.02％、V:0.05％、B:0.003％，余量为Fe；锰镀层在钢板上的附着量为40g/㎡(换算为厚度约为5μm)，锰系镀覆层中以质量％计，锰含量≥99％。
接着，将具有锰镀层的钢卷进行落料以获得坯料，落料的方式可以是模具冷冲压，也可以是激光切割。
接着，将上述坯料放入氧含量控制在0.0002％以下的真空加热炉内加热360秒至900℃，使钢板发生奥氏体化，同时，钢板和锰镀层发生合金化。
接着，向真空加热炉内通入氮气以对加热完成的坯料进行预冷3秒钟，预冷后的坯料表面温度为750℃。
接着，将预冷后的坯料从真空加热炉中取出，在氮气保护气氛下送入模具内成型，获得成型产品。
接着，将热成型产品经过激光切割和抛丸处理，制成超高强钢汽车零件。
对比例1
首先，对厚度为1.5mm的AS60/60铝硅镀层钢卷进行落料以获得坯料，其中铝硅镀层钢表面的铝硅镀层的附着量为75g/㎡(换算为厚度约为25μm)。
接着，将上述坯料放入保护性气氛炉内加热300秒至930℃。
接着，将加热完成后的坯料放入模具中成型，以获得产品。
接着，将产品经过激光切割和气孔，制成超高强钢汽车零件。
对上述案例1～3以及对比例1进行三点弯曲试验，试验的结果如表1所示。
表1案例1～3与对比例1的冷弯性能对比
零件编号 三点弯曲1 三点弯曲2 平均值
案例1 75.2° 81.3° 78.3°
案例2 89.3° 89.2° 89.3°
案例3 91.4° 90.6° 91.0°
对比例1 50.8° 52.7° 51.8°
结论：由上表1的数据可以看出，案例1～3的热成型产品的三点弯曲角度均大于60°，案例1～3的三点弯曲角度明显优于对比例1的三点弯曲角度。且随着热成型产品表面的锰系镀覆层的附着量越大，其三点弯曲角度越大，这是因为随着锰系镀覆层的附着量越大(厚度越大)，热成型之后，镀覆层中的γ相铁锰固溶体和β相锰铁固溶体合金越多，由于γ相铁锰固溶体和β相锰铁固溶体合金具有良好的韧性和塑性，有利于提高产品的三点弯曲性能。
对上述案例1～3进行表面粗糙度测量，测量的结果如表2所示。
表2案例1～3的表面粗糙度
Figure PCTCN2020102264-appb-000001
由上表2中的数据可以看出，本实施例中的热成型产品，其表面的粗糙度低于1.3μm，符合汽车行业对镀层零件的表面粗糙度的要求(目前，汽车行业对镀锌层零件表面的粗糙度要求为介于0.8～1.3μm之间)。
对上述案例2和对比例1进行盐雾试验，试验结果表明，对比例1在试验至第6小时的时候已经出现明显腐蚀(如图4所示，其表面具有大量锈迹)，而案例2在试验至第120小时的时候尚未出现腐蚀(如图5所示，其表面几乎没有锈迹)。由此可见，本实施例的锰系镀覆钢板在热成型后的耐腐蚀性能远超铝硅涂层钢板的热成型产品。
对上述案例1(锰系镀覆层附着量为40g/㎡，换算为厚度约是5μm)中的热成型产品进行EDS元素分析，以测定案例1的热成型产品中，距离产品表面不同深度的位置的铁、锰、碳和氧元素的含量，测定结果如下表3所示。采用SEM(Scanning Electron Microscope，扫描电子显微镜)分析了案例1的显微结构，其结果如图6所示，并采用XRD(X-ray Diffraction，X射线衍射)分析了案例1的相结构，其结果如图7所示。
表3距离产品表面不同深度的位置的铁、锰、碳和氧元素的含量(质量％)
距离产品表面深度 Fe％ Mn％ C％ O％
15um 95.18 0 4.82 0
14um 95.15 0 4.85 0
13um 94.49 0 5.01 0
12um 94.49 0 5.01 0
11um 94.49 0 5.51 0
10um 94.27 0 5.73 0
9um 94.09 0 5.91 0
8um 93.39 0 6.61 0
7um 93.6 0 6.4 0
6um 84.71 9.14 6.15 0
5um 66.44 21.52 6.76 0
4um 52.7 32.77 7.01 7.52
3um 29.43 49.66 8.31 12.6
2um 19.85 59.68 10.14 10.33
1um 16.83 59.22 13 10.95
结合图6、图7和表3的结果可知，经过热成型后，案例1表面的镀覆层具有约5.5μm的总厚度，主要分为三个结构层。最靠近钢板的铁基体的一层为α+γ相铁锰组织，其厚度约为1.233μm；最外一层为锰的氧化物，其厚度约为2.666μm；中间一层为β相锰铁固溶体，其厚度约为1.667μm。
案例1中，中间层的β相锰铁固溶体，其锰含量在50％左右，具有良好的耐腐蚀性能，可以有效的保护钢体基体。而最内层的α+γ相铁锰奥氏体组织具有良好的韧性，可以提高零件的冲击吸能效果，因此5-8um镀锰层的三点弯曲均值在78.3°。因此5-8um左右的镀锰层可以用于防腐蚀要求不高的场合。
对上述案例3(锰系镀覆层附着量为90g/㎡，换算为厚度约是12μm)中的热成型产品进行EDS元素分析，以测定案例3的热成型产品中，距离产品表面不同深度的位置的铁、锰、碳和氧元素的含量，测定结果如下表4所示。采用SEM(Scanning Electron Microscope，扫描电子显微镜)分析了案例3的显微结构，其结果如图8所示，并采用XRD(X-ray Diffraction，X射线衍射)分析了案例3的相结构，其结果如图9所示。
表4距离产品表面不同深度的位置的铁、锰、碳和氧元素的含量(质量％)
距离产品表面深度 Fe％ Mn％ C％ O％
18um 93.06 0.00 6.94 0.00
17um 92.24 0.00 7.76 0.00
16um 91.85 0.00 8.15 0.00
14um 73.20 18.60 8.20 0.00
13um 53.53 37.97 8.50 0.00
12um 40.21 48.60 7.96 3.23
11um 37.47 48.98 9.00 4.55
10um 29.47 54.41 8.60 7.52
8um 21.80 60.47 8.31 9.42
7um 14.54 70.93 7.01 7.52
6um 15.32 65.77 8.31 10.60
5um 11.97 69.50 7.01 11.52
3um 7.49 71.37 8.54 12.60
1um 11.70 62.83 10.14 15.33
结合图8、图9和表4可以看出，经过热成型后，案例3表面的镀覆层具有约12μm的厚度，主要分为三个结构层。最靠近钢板的铁基体的一层为α+γ相铁锰组织，其厚度约为3μm；最外一层为锰的氧化物，其厚度约为2～3μm之间；中间一层为β相锰铁固溶体，其厚度约为5～8μm。
由于案例3中的β相锰铁固溶体的厚度高达5～8μm，具有优异的牺牲阳极保护效果，案例3的该效果明显优于案例1的该效果。另外，由于案例3的α+γ相铁锰组织厚度也较大，尤其是是γ相铁锰组织厚度要大于案例1中γ相铁锰组织的厚度，因此，案例3的三点弯曲角度明显优于案例1的三点弯曲角度。
案例4中，通过薄涂层，充分合金化，电极电位与钢铁基体基本一致，虽然无优异的牺牲阳极保护效果，但薄涂层可以节省成本，提高三点弯曲性能以及焊接性能。
本发明中应用了具体实施例对本发明的原理及实施方式进行了阐述，以上实施例的说明只是用于帮助理解本发明的方法及其核心思想；同时，对于本领域的一般技术人员，依据本发明的思想，在具体实施方式及应用范围上均会有改变之处，综上所述，本说明书内容不应理解为对本发明的限制。

Claims (21)

  1. 一种锰系镀覆钢板，其特征在于，包括钢板和设置于所述钢板的两面的锰系镀覆层，其中，所述钢板上的锰系镀覆层的附着量在40g/㎡～110g/㎡之间，所述锰系镀覆层中以质量％计，Mn的含量大于或等于80％。
  2. 根据权利要求1所述的钢板，其特征在于，所述钢板上的锰系镀覆层的附着量在70g/㎡～100g/㎡之间。
  3. 根据权利要求1所述的钢板，其特征在于，所述锰系镀覆层包括纯锰、锰铁合金、锰锌合金、锰铝合金、锰镍合金、锰锌镍合金、锰铝镍合金、锰铬合金、锰锌铬合金或锰铝铬合金中的一种或多种。
  4. 根据权利要求1所述的钢板，其特征在于，所述钢板以质量％计，其中，各组分含量为C:0.1％～0.4％、Mn:0.5％～2.0％、Al:0.005％～0.1％、B:0.001％～0.010％。
  5. 根据权利要求4所述的钢板，其特征在于，所述钢板还包括，以质量％计，
    Ti:0.01％～0.20％，和/或Nb:0.01％～0.20％，和/或V:0.1％～0.5％中的一种或多种。
  6. 根据权利要求4所述的钢板，其特征在于，所述钢板还包括，以质量％计，Cr:0.1％～0.5％，和/或Mo:0.1％～0.5％，和/或Cu:0.1％～0.5％，和/或Ni:0.1％～0.5％中的一种或多种。
  7. 根据权利要求1所述的钢板，其特征在于，所述锰系镀覆层通过电镀工艺附着在所述钢板上。
  8. 根据权利要求1所述的钢板，其特征在于，两个所述锰系镀覆层远离所述钢板的一面还分别设有镍镀层或铁镀层，所述镍镀层或铁镀层的厚度小于1μm。
  9. 一种如权利要求1至8中任意一项所述的锰系镀覆钢板的热成型方法，其特征在于，包括以下步骤：
    将所述锰系镀覆钢板放置于加热炉中加热至860～950℃，使所述锰系镀覆钢板中的钢板奥氏体化，所述加热炉中以质量％计，氧的含量小于0.02％；
    将加热至860～950℃后的所述锰系镀覆钢板放入模具中成型，获得热成型产品。
  10. 根据权利要求9所述的方法，其特征在于，所述加热炉为真空加热炉。
  11. 根据权利要求9所述的方法，其特征在于，所述奥氏体保温时间在0～10分钟之间。
  12. 根据权利要求10所述的方法，其特征在于，在所述锰系镀覆钢板加热后且出炉之前，向所述真空加热炉内通入纯度为99.999％以上的氮气以对所述锰系镀覆钢板进行 预冷1～10秒，预冷后的所述锰系镀覆钢板的温度介于600～860℃之间。
  13. 根据权利要求12所述的方法，其特征在于，所述锰系镀覆钢板的预冷时间在1～3秒之间。
  14. 根据权利要求11所述的方法，其特征在于，预冷后的所述锰系镀覆钢板的温度介于750～800℃之间。
  15. 根据权利要求9所述的方法，其特征在于，所述加热炉为保护性气氛炉。
  16. 根据权利要求9所述的方法，其特征在于，所述加热炉中以质量％计，氧的含量小于0.002％。
  17. 根据权利要求9所述的方法，其特征在于，所述锰系镀覆钢板在保护性气氛保护下被送入所述模具中，所述模具设置在所述保护性气氛中，所述保护性气氛中以质量％计，氧的含量小于3％。
  18. 根据权利要求9所述的方法，其特征在于，所述锰系镀覆钢板在所述模具合模瞬间的温度大于550℃。
  19. 一种热成型产品，其特征在于，其采用如权利要求9至17中任意一项所述的方法制备。
  20. 根据权利要求18所述的热成型产品，其特征在于，所述热成型产品的锰系镀覆层包括附着在钢板表面的γ相铁锰固溶体合金层和附着在所述γ相铁锰固溶体层远离所述钢板的一面的β相锰铁固溶体合金层。
  21. 根据权利要求19所述的热成型产品，其特征在于，所述γ相铁锰固溶体合金层的厚度不小于1μm，所述β相锰铁固溶体合金层的厚度介于5～15μm之间，所述γ相铁锰固溶体合金层和所述β相锰铁固溶体合金层的总厚度介于6～20μm之间。
PCT/CN2020/102264 2020-06-10 2020-07-16 一种锰系镀覆钢板及其热成型方法和热成型产品 WO2021248626A1 (zh)

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