Hot forming process of 22mnb5 steel with high quality zinc-based coating

Abstract

The application is a 22MnB5 steel hot forming process with high quality zinc-based plating. The process comprises the following steps: placing hot galvanizing 22MnB5 hot forming steel plate in a heating furnace at 900-910 DEG C, rapidly increasing the temperature to the austenitizing temperature interval (i.e. 900-910 DEG C) at a heating rate of 20-50 DEG C / min, keeping the temperature for 5-7 min, taking the steel plate out of the furnace, transferring it to a hot forming die within 2-5 s, and quenching it to room temperature by water cooling in the die to complete the hot forming process. The application can shorten the heat treatment process cycle, improve the production efficiency, reduce the energy consumption, and improve the corrosion resistance and service life of the steel plate.

Description

Technical Field

[0001] The invention relates to a 22MnB5 steel hot forming process with a high-quality zinc-based coating, and belongs to the technical field of hot-dip galvanized hot-formed steel production. Background Art

[0002] With the increasing demand for lightweight and safety performance in automobiles, ultra-high-strength steel has gained widespread application and is currently a major development trend in automotive steel structural materials. 22MnB5 hot-formed steel, with a strength exceeding 1500 MPa, is widely used in key safety components such as doors and anti-collision beams. To improve component corrosion resistance, hot-formed steel components are typically produced through a hot-forming process using a hot-dip galvanized hot-formed steel substrate.

[0003] Hot forming requires austenitizing heat treatment of the steel sheet. Hot-dip galvanized hot-formed steel substrates inevitably experience zinc melting and surface oxidation, which affects the structure and quality of the galvanized surface and ultimately the performance of subsequent coatings. Therefore, an optimized heat treatment process is needed to reduce the degree of surface oxidation and ensure the quality of the galvanized layer.

[0004] The document with Chinese patent application number 202211267789.8 discloses "A hot forming process for reducing the color difference on the surface of hot-dip galvanized thermoformed steel", which subjects the hot-dip galvanized steel sheet to an austenitizing heat treatment temperature in the temperature range of 870-890°C, keeps the temperature for 2-10 minutes, and then uses air cooling to cool the galvanized sheet to room temperature. Although the hot forming process reported in this document can effectively reduce the color difference on the surface of hot-dip galvanized thermoformed steel sheet, it does not involve the fine microstructure treatment of the galvanized layer after heat treatment. Since the microstructure of the coating directly determines the corrosion resistance of the steel sheet, the development of a heat treatment process that can prepare a coating with an excellent structure is of significance to improving the surface quality of hot-dip galvanized steel sheet and its practical application effect. Summary of the Invention

[0005] The purpose of the present invention is to provide a 22MnB5 steel hot forming process with a high-quality zinc-based coating in response to the shortcomings of the current technology. This process obtains a zinc layer with an optimal thickness by proposing a heat treatment process system of rapid heating + high-temperature austenitizing treatment, and forms a continuous and dense Al2O3 protective layer on its surface, thereby reducing the volatilization of zinc in the coating and avoiding the oxidation of the zinc coating, while effectively avoiding the formation of large-sized harmful oxides. The present invention proposes a process system of rapid heating + high-temperature austenitizing treatment, which can shorten the heat treatment process cycle, improve production efficiency, and reduce energy consumption. A high-quality zinc-plated layer structure of zinc layer + Al2O3 protective layer is prepared, which significantly improves the protective effect of the zinc-based coating on the 22MnB5 steel plate, and enhances the corrosion resistance and service life of the steel plate.

[0006] The technical solution of the present invention is:

[0007] A hot forming process for 22MnB5 steel with a high-quality zinc-based coating comprises the following steps:

[0008] (1) Raise the heating furnace temperature to the austenitizing temperature, i.e. 900-910°C, in advance and keep it at that temperature for 5-10 minutes to ensure uniform temperature distribution in the furnace;

[0009] (2) Place the hot-dip galvanized 22MnB5 hot-formed steel sheet in a heating furnace and rapidly heat it to the austenitizing temperature range (i.e., 900-910°C) at a heating rate of 20-50°C / min, and keep it at this temperature for 5-7 minutes to ensure that the microstructure is completely transformed into austenite;

[0010] (3) The heat-treated steel plate is taken out of the furnace and transferred to a hot forming mold within 2 to 5 seconds, and quenched to room temperature by water cooling in the mold to complete the hot forming process.

[0011] The surface of the hot-dip galvanized 22MnB5 steel sheet finally obtained has an Al2O3 oxide layer with a thickness of 3 to 4 μm.

[0012] The chemical elements and contents of the 22MnB5 steel are as follows: C: 0.10-0.30 wt.%, Si: 0-0.3 wt.%, Mn: 1.00-1.50 wt.%, Al: 0.02-0.04 wt.%, Ti: 0.03-0.05 wt.%, Ni: 0.01-0.03 wt.%, B: 0.002-0.004 wt.%, P < 0.02 wt.%, S < 0.002 wt.%, and the balance is Fe and unavoidable impurities.

[0013] The chemical elements and their contents in the zinc solution used for hot-dip galvanizing are: Al: 0.15-0.18wt.%, Fe: 0.03-0.05wt%, and the balance is Zn and unavoidable impurities;

[0014] The preparation of the hot-dip galvanized 22MnB5 hot-formed steel sheet comprises the following steps: obtaining a 22MnB5 steel ingot meeting the above-mentioned chemical composition requirements by smelting, heating the ingot to 1150-1250°C, holding the temperature for 1-2 hours, starting rolling at 1100-1150°C, finishing rolling at a temperature not lower than 900°C, hot rolling reduction at a rate not lower than 75%, and coiling at a temperature of 600-750°C;

[0015] The hot-rolled plate is pickled and then cold-rolled with a cold-rolling reduction of not less than 70%, and the plate thickness after cold rolling is 1-2 mm. Continuous annealing is then performed at a temperature of 750-800°C for 5-8 minutes.

[0016] After annealing, the steel plate is immediately hot-dip galvanized. The zinc pot temperature is 450-470°C and the hot-dip galvanizing time is 2-5 seconds.

[0017] Through the above process, a hot-dip galvanized 22MnB5 steel sheet with a zinc coating thickness of about 20 to 30 μm is finally prepared;

[0018] The essential features of the present invention are:

[0019] In the current technology, the heating rate of heat treatment in conventional hot forming processes is slow, which increases the time the workpiece spends in the furnace and increases the oxide content on the surface of the steel plate coating. In addition, the heating temperature is low (850-890°C), which is not conducive to the diffusion of alloying elements such as Al, and restricts the density and continuity of the Al2O3 protective layer formed on the coating surface. Based on the above shortcomings, the present invention improves the heating rate of heat treatment (20-50°C / minute) and the austenitizing temperature (900-910°C). The fast heating rate can reduce the time the steel plate spends in the furnace, reduce the high-temperature oxidation time, and thus reduce the formation of harmful oxides on the surface. The use of a high austenitizing temperature can increase the diffusion capacity of alloying elements by increasing the temperature, which is beneficial to the formation of the iron-zinc alloy layer, and is also beneficial for the Al element to diffuse through the zinc layer to form an Al2O3 layer on its surface, thereby protecting the zinc layer.

[0020] The beneficial effects of the present invention are:

[0021] The above technical solution was used to implement the hot forming process of 22MnB5 steel. By rationally increasing the heating rate and austenitizing temperature, the furnace time of the steel plate was effectively reduced, and the diffusion capacity of the alloying elements during the heat treatment process was improved. 22MnB5 steel with a high-quality zinc-based coating was produced. The fine structure of the coating is as follows:

[0022] (1) The zinc layer is mainly composed of α-Fe(Zn) phase and a small amount of Fe3Zn 10 Phase composition, thickness 20-30 μm;

[0023] (2) A continuous and dense Al2O3 film with a thickness of 3 to 4 μm is formed on the surface of the zinc layer, and no large-sized Mn oxides or oxides are generated inside the zinc layer;

[0024] The above-mentioned excellent coating structure can effectively block the contact between the steel plate substrate and media such as air, improve corrosion resistance, and greatly extend service life. In addition, compared with the traditional process (austenitizing temperature 2 to 10 minutes), this patent adopts rapid heating + short-time (5 to 7 minutes) high-temperature austenitizing heat treatment, which can shorten the hot forming process cycle, reduce energy consumption and manufacturing costs, and facilitate industrial production. Compared with the "A Hot Forming Process for Reducing the Surface Color Difference of Hot-Dip Galvanized Hot-Formed Steel" disclosed in the document No. 202211267789.8 of Chinese Patent Application, the hot forming process in the present invention prepares an Al2O3 oxide layer with a thickness of 3 to 4 μm and better density, and no Mn oxide particles are found in the structure, which optimizes the microstructure of the coating. BRIEF DESCRIPTION OF THE DRAWINGS

[0025] Figure 1 Schematic diagram of the heat treatment process of the present invention;

[0026] Figure 2 is the calculation result of the complete austenitization temperature of the hot-formed steel in Example 1;

[0027] Figure 3 This is the SEM-EDS image of the hot-dip galvanized layer obtained in Example 1;

[0028] Figure 4 TEM-EDS images of the zinc layer and the surface oxide layer obtained in Example 1;

[0029] Figure 5 TEM-EDS image of the zinc layer position obtained in Example 1 and its diffraction calibration;

[0030] Figure 6 This is the SEM-EDS image of the hot-dip galvanized layer of the Voestalpine product described in Example 1;

[0031] Figure 7 This is the SEM-EDS image of the hot-dip galvanized layer obtained in Example 2;

[0032] Figure 8 This is the SEM-EDS image of the hot-dip galvanized layer obtained in Example 3; DETAILED DESCRIPTION

[0033] The embodiments described below with reference to the accompanying drawings are exemplary and are intended to be used to explain the present application, but should not be understood as limiting the present application.

[0034] The following describes the thermoforming process described in this application in detail with reference to the embodiments.

[0035] The chemical elements and contents of 22MnB5 hot-forming steel are: C: 0.10~0.30wt.%, Si: 0.1~0.3wt.%, Mn: 1.00~1.50wt.%, Al: 0.02~0.04wt.%, Ti: 0.03~0.05wt.%, Ni: 0.01~0.03wt.%, B: 0.002~0.004wt.%, P<0.02wt.%, S<0.002wt.%, and the balance is Fe and unavoidable impurities.

[0036] Carbon is the main strengthening element in steel. Strength and hardness increase with increasing carbon content. However, excessive carbon content will deteriorate the plasticity and weldability of steel. Therefore, the carbon content design principle should be to adopt ultra-low carbon design principle as much as possible while ensuring strength. In this application, the carbon content is selected to be 0.10-0.30wt.%;

[0037] On the one hand, Si element can effectively inhibit the formation of carbides and improve hardenability. On the other hand, it can also reduce the volume expansion during the martensitic phase transformation and prevent crack formation. In this application, the Si content is selected to be 0.10-0.30wt.%;

[0038] Mn is an effective austenite stabilizing element, which can promote the enrichment of C into austenite and increase the content of retained austenite. In this application, the Mn content is selected to be 1.00-1.50 wt.%;

[0039] Ti is a high melting point alloying element. As a microalloying element in steel, it can combine with elements such as C and N to form carbides, thereby preventing the growth of austenite grains. In this application, the Ti content is selected to be 0.03-0.05 wt.%;

[0040] The B element in steel can significantly improve the hardenability of the material, stabilize the size and morphology of martensite laths, and strengthen grain boundaries. In this application, the B content is selected to be 0.002-0.004 wt.%.

[0041] Example 1

[0042] A 22MnB5 steel ingot meeting the above chemical composition requirements is obtained by smelting, and the ingot is heated to 1200°C, kept at this temperature for 1 hour, and subjected to a starting rolling temperature of 1100°C, a finishing rolling temperature of 950°C, a hot rolling reduction rate of 80%, and a coiling temperature of 650°C;

[0043] The hot-rolled sheets were pickled and then cold-rolled to a thickness of 1.5 mm at a 70% reduction. They were then continuously annealed at 750°C for 5 minutes.

[0044] After annealing, the steel sheet was immediately subjected to hot-dip galvanizing treatment. The zinc bath temperature was 465°C, the hot-dip galvanizing time was 5 seconds, the Al content in the zinc bath was 0.15wt%, the Fe content was 0.03wt%, and the remainder was Zn.

[0045] Through the above process, a hot-dip galvanized 22MnB5 steel plate is prepared.

[0046] Raise the heating furnace temperature to the austenitizing temperature of 900°C and keep it at that temperature for 10 minutes to ensure uniform temperature distribution in the furnace;

[0047] The hot-dip galvanized 22MnB5 hot-formed steel sheet was placed in a heating furnace and rapidly heated to the austenitizing temperature range at a heating rate of 30°C / min and kept at this temperature for 6 minutes. Figure 2 As shown in Figure 2, the critical temperature for complete austenitization of the alloy is 813°C. Therefore, when the hot-formed steel plate is heated to 900°C, the microstructure is completely transformed into austenite.

[0048] After heat treatment, the steel plate is removed from the furnace and transferred to the hot forming mold in 3 seconds. It is punched into a fixed geometric shape part and quenched to room temperature by water cooling in the mold to complete the hot forming process.

[0049] Metallographic samples were cut from hot-dip galvanized hot-formed plates. After grinding and polishing, the cross-section of the samples was observed using the SEM-EDS function of the TESCAN GAIA3Ga ion dual-beam scanning electron microscope, focusing on the galvanized layer and the surface oxides, as shown in the attached figure. Figure 3 As shown. The SE diagram is the result of secondary electron imaging, and the other alloy element diagrams are the quantitative analysis results of the alloy elements at the scanning position of the SE diagram. The brighter the color, the higher the content of the alloy element. From the Zn element distribution diagram, we can see that the thickness of the zinc layer is 30.4μm; from the Al element distribution diagram, we can see that the Al2O3 layer is continuous and dense, with a thickness of about 3.8μm; from the Mn element distribution diagram, we can see that the galvanized layer does not contain Mn oxides and inner oxides; a transmission sample was cut from the hot-formed plate, and after grinding and ion thinning, the sample cross section was observed using TEM-EDS, as shown in the attached figure. Figure 4 As shown. The HADDF diagram is the TEM morphology of the zinc layer and the surface oxide, and the diagrams of other alloy elements are the distribution results of the alloy elements at this position. It can be seen from the Al and Zn element distribution diagrams that there are continuous Al-rich and Zn oxide layers on the surface of the coating, which are Al2O3 layers and ZnO layers. This is because the present invention adopts rapid heating means to reduce the time that hot-formed steel is in the furnace. On the one hand, it reduces the degree of oxidation and effectively prevents the formation and amount of Mn oxides. On the other hand, it reduces the volatilization of zinc elements and ensures the thickness of the zinc layer. At the same time, the present invention also adopts high-temperature austenitization means to effectively improve the diffusion capacity of alloy elements, especially Al elements, so that it forms a dense and continuous oxide layer on the surface of the galvanized layer.

[0050] The coating cross section was observed using a JEM-2100F high-resolution transmission electron microscope, and the diffraction spots were used to calibrate the phase crystal structure. Figure 5 As shown. The HADDF image is the TEM morphology of the zinc layer and the surface oxide, and the other alloy element images are the distribution results of the alloy elements at that position. Figures (ab) are the diffraction patterns and calibration results of the corresponding positions in the HADDF image. From the calibration results, it can be seen that the zinc layer is mainly composed of α-Fe(Zn) phase, Fe3Zn 10 Phase composition. This is because during the heat treatment process, the Fe element in the hot-formed steel matrix diffuses into the zinc layer and then reacts chemically with the Zn element to form various Fe-Zn compounds.

[0051] The zinc layer thickness of the hot-dip galvanized steel sheet prepared by the hot forming parameters of the present invention is appropriate, and a continuous and dense Al2O3 layer is formed on the surface. At the same time, no Mn surface oxides and internal oxides are found, indicating that the Al2O3 layer can effectively block the zinc layer from contacting with air and play a protective role. The fine structure of the zinc layer is mainly composed of α-Fe(Zn) phase, with only a small amount of brittle Fe3Zn 10 phase, which can ensure that the zinc layer has good plastic toughness and reduce the risk of cracking during deformation. Figure 3 As shown in Figure SE, no cracks were found in the zinc layer.

[0052] Figure 6 The SEM-EDS results of the cross-section of the hot-dip galvanized thermoformed steel coating of Voestalpine Corporation are shown. The company's products have excellent corrosion resistance. The hot-dip galvanized thermoformed steel obtained by the present invention has a similar zinc coating thickness to that of Voestalpine products (the zinc coating thickness of this embodiment is 30.4 μm, and that of Voestalpine products is 31.1 μm). At the same time, both form an Al2O3 layer on the coating surface. The oxide layer thickness of this embodiment is 3.8 μm, and that of Voestalpine products is 2.1 μm. In summary, the coating structure of this embodiment is very close to that of Voestalpine products. However, since this embodiment adopts a high-temperature austenitization process, the energy expansion capacity of the Al element in the zinc layer is improved, and an Al2O3 oxide layer with a thickness of 3.8 μm and better density is obtained, which effectively blocks corrosive media such as air from contacting the coating, and can greatly improve the service life and corrosion resistance.

[0053] Example 2

[0054] This example provides an analysis of the coating structure of hot-dip galvanized hot-formed steel under a low heating rate (heating with the furnace) process, which facilitates comparison with the rapid heating process of the present invention.

[0055] A 22MnB5 steel ingot meeting the above chemical composition requirements is obtained by smelting, and the ingot is heated to 1200°C, kept at this temperature for 1 hour, and subjected to a starting rolling temperature of 1100°C, a finishing rolling temperature of 950°C, a hot rolling reduction rate of 80%, and a coiling temperature of 650°C;

[0056] The hot-rolled sheets were pickled and then cold-rolled to a thickness of 1.5 mm at a 70% reduction. They were then continuously annealed at 750°C for 5 minutes.

[0057] After annealing, the steel sheet was immediately subjected to hot-dip galvanizing treatment. The zinc bath temperature was 465°C, the hot-dip galvanizing time was 5 seconds, the Al content in the zinc bath was 0.15wt%, the Fe content was 0.03wt%, and the remainder was Zn.

[0058] Through the above process, a hot-dip galvanized 22MnB5 steel plate is prepared;

[0059] The 22MnB5 steel plate was placed in a heating furnace and heated to the austenitizing temperature of 900°C. The temperature was kept at this temperature for 400 seconds to transform the microstructure into austenite.

[0060] After heat treatment, the steel plate is removed from the furnace, transferred to the hot forming mold in 3 seconds, and quenched to room temperature by water cooling in the mold to complete the hot forming process.

[0061] Metallographic samples were cut from the hot-formed plate, and after grinding and polishing, the cross-section of the sample was observed using SEM-EDS, with attention paid to the zinc coating and surface oxides, as shown in the attached figure. Figure 7 As shown. The SE diagram is the result of secondary electron imaging, and the other alloy element diagrams are the results of quantitative analysis of the alloy elements at the scanning position of the SE diagram. The brighter the color, the higher the content of the alloy element. From the Zn element distribution diagram, it can be seen that the thickness of the zinc layer is about 24μm; from the Al element distribution diagram, it can be seen that no obvious Al2O3 protective layer is found on the surface of the coating; from the Mn and Zn element distribution diagrams, it can be seen that no Mn oxides and internal oxides are found, but a zinc oxide layer with a thickness of up to 19μm is formed on the surface of the zinc layer. The formation of the zinc oxide layer will consume the Zn element in the zinc layer and reduce the thickness of the zinc layer. On the other hand, the thick zinc layer is very easy to crack and fall off during deformation, exposing the zinc layer and losing its protective effect.

[0062] Compared to the rapid heating and high-temperature austenitization method proposed in this invention, furnace heating (a slow heating rate) results in a prolonged time in the furnace, allowing the zinc layer to react fully with air, forming a thick zinc oxide layer. This zinc oxide layer also hinders the formation of an Al2O3 layer on the surface, ultimately preventing the formation of a continuous and dense Al2O3 layer on the zinc surface.

[0063] Example 3

[0064] This example provides an analysis of the coating structure of hot-dip galvanized hot-formed steel under low-temperature austenitization treatment, which facilitates comparison with the high-temperature austenitization process of the present invention;

[0065] A 22MnB5 steel ingot meeting the above chemical composition requirements is obtained by smelting, and the ingot is heated to 1200°C, kept at this temperature for 1 hour, and subjected to a starting rolling temperature of 1100°C, a finishing rolling temperature of 950°C, a hot rolling reduction rate of 80%, and a coiling temperature of 650°C;

[0066] The hot-rolled sheets were pickled and then cold-rolled to a thickness of 1.5 mm at a 70% reduction. They were then continuously annealed at 750°C for 5 minutes.

[0067] After annealing, the steel sheet was immediately subjected to hot-dip galvanizing treatment. The zinc bath temperature was 465°C, the hot-dip galvanizing time was 5 seconds, the Al content in the zinc bath was 0.15wt%, the Fe content was 0.03wt%, and the remainder was Zn.

[0068] Through the above process, a hot-dip galvanized 22MnB5 steel plate is prepared;

[0069] Raise the heating furnace temperature to the austenitizing temperature of 870°C and keep it at that temperature for 10 minutes to ensure uniform temperature distribution in the furnace;

[0070] The hot-dip galvanized 22MnB5 hot-formed steel sheet was placed in a heating furnace and rapidly heated to the austenitizing temperature range for 400 seconds to transform the microstructure into austenite.

[0071] After heat treatment, the steel plate is taken out of the furnace and quickly transferred to the hot forming mold, and quenched to room temperature by water cooling in the mold to complete the hot forming process.

[0072] Metallographic samples were cut from the hot-formed plate, and after grinding and polishing, the cross-section of the sample was observed using SEM-EDS, with attention paid to the zinc coating and surface oxides, as shown in the attached figure. Figure 8 The SE image is the secondary electron imaging result, and the other alloying element images are the quantitative analysis results of the alloying elements at the scanning position of the SE image. The brighter the color, the higher the content of the alloying element. The Zn element distribution map shows that the zinc layer thickness is approximately 30μm. The Mn and Al element distribution maps show that no Mn oxides or internal oxides are found, and no Al2O3 protective layer is found on the coating surface.

[0073] Compared with the rapid heating + high-temperature austenitizing treatment method proposed in the present invention, when the austenitizing temperature is lower (870°C), the diffusion ability of the alloy elements is relatively reduced, making it difficult for the Al element in the matrix to diffuse through the zinc layer. Ultimately, no continuous and dense Al2O3 protective layer is obtained on the surface, and the zinc layer cannot be effectively protected.

[0074] Through the above characterization and comparative analysis, it can be seen that the surface of the steel plate prepared by the hot forming process proposed in this application has a continuous and dense Al oxide layer, and there is no large-sized Mn oxide, which has a good protective effect on the steel matrix; the zinc layer is mainly composed of α-Fe(Zn) phase, and a small amount of brittle Fe3Zn 10 In summary, the present application prepares a 22MnB5 steel plate with a high-quality zinc-based coating.

[0075] Although the embodiments of the present invention have been shown and described above, it will be understood that the above embodiments are illustrative and are not to be construed as limitations on the present invention. A person skilled in the art may change, modify, replace and modify the above embodiments within the scope of the present invention.

[0076] Matters not covered by the present invention are known technologies.

Claims

1. A hot forming process for 22MnB5 steel with a high-quality zinc-based coating, characterized in that the process comprises the following steps: (1) Raise the heating furnace temperature to the austenitizing temperature, i.e. 900~910℃, in advance and keep it warm for 5~10 minutes to ensure uniform temperature distribution in the furnace; (2) The hot-dip galvanized 22MnB5 hot-formed steel sheet is placed in a heating furnace and rapidly heated to the austenitizing temperature range of 900-910°C at a heating rate of 20-50°C / min, with a holding time of 5-7 minutes; (3) The heat-treated steel plate is taken out of the furnace and transferred to the hot forming mold within 2 to 5 seconds, and quenched to room temperature by water cooling in the mold to complete the hot forming process; The resulting hot-dip galvanized 22MnB5 steel sheet has an Al2O3 oxide layer on its surface with a thickness of 3-4 μm. The chemical elements and contents of the 22MnB5 steel are as follows: C: 0.10-0.30 wt.%, Si: 0-0.3 wt.%, Mn: 1.00-1.50 wt.%, Al: 0.02-0.04 wt.%, Ti: 0.03-0.05 wt.%, Ni: 0.01-0.03 wt.%, B: 0.002-0.004 wt.%, P < 0.02 wt.%, S < 0.002 wt.%, and the balance is Fe and unavoidable impurities. The chemical elements and their contents in the zinc liquid used for hot-dip galvanizing are: Al: 0.15~0.18 wt.%, Fe: 0.03~0.05 wt%, and the balance is Zn and unavoidable impurities.

2. The hot forming process for 22MnB5 steel with a high-quality zinc-based coating according to claim 1, wherein the preparation of the hot-dip galvanized 22MnB5 hot-formed steel sheet comprises the following steps: A 22MnB5 steel ingot meeting the above chemical composition requirements is obtained by smelting, the ingot is heated to 1150-1250°C, kept warm for 1-2 hours, the starting rolling temperature is 1100-1150°C, the finishing rolling temperature is not less than 900°C, the hot rolling reduction rate is not less than 75%, and the coiling temperature is 600-750°C; The hot-rolled plate is pickled and then cold-rolled, with a cold-rolling reduction of not less than 70%, and the plate thickness after cold rolling is 1-2 mm, followed by continuous annealing treatment, with an annealing temperature of 750-800° C. and a holding time of 5-8 minutes; After annealing, the steel plate is immediately hot-dip galvanized. The zinc pot temperature is 450~470℃ and the hot-dip galvanizing time is 2~5 seconds. Through the above process, a hot-dip galvanized 22MnB5 steel sheet with a zinc coating thickness of 20-30 μm is finally prepared.

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