Hot-forming method for zinc-based coated steel plate, coated steel plate, hot-formed component, and hot-forming system

Abstract

A hot-forming method for a zinc-based coated steel plate, comprising the steps of: heating a zinc-based coated steel plate to reach a fully austenitized state; air-cooling the heated zinc-based coated steel plate; further cooling the air-cooled zinc-based coated steel plate by high-pressure jet cooling while removing an oxide layer on a surface of the coating; and performing final forming on the cooled zinc-based coated steel plate. Also disclosed are a hot-forming system, a zinc-based coated steel plate, and a zinc-based coated steel plate component. According to the hot-forming method, the uniform controlled cooling effect of a high-temperature spraying medium prevents cracking caused by brittleness of liquid metal on the surface of the coated steel plate; the formed hot-formed component has good surface quality, which ensures the strength of a formed steel plate and can also prevent the brittleness problem of the liquid metal.

Description

A hot forming method for zinc-based coated steel sheet, the coated steel sheet, hot forming components, and hot forming system thereof. Technical Field

[0001] This invention belongs to the field of steel parts processing, and specifically relates to a hot forming method for zinc-based coated steel sheets, as well as the coated steel sheet, hot forming components, and hot forming system. Background Technology

[0002] Hot stamping technology fully leverages the advantages of lightweight materials and advanced manufacturing processes, becoming a specialized forming technology for high-strength and ultra-high-strength steels. From the initial uncoated hot-formed steel to aluminum-silicon coated hot-formed steel and now to zinc-based coated hot-formed steel, the entire development process has gradually solved a series of technological challenges such as cumbersome processes and poor corrosion resistance.

[0003] The overall process route for hot-formed steel is: "heating-holding-quenching and forming". For zinc-based coated hot-formed steel, the forming process requires more precise temperature control. The coated steel sheet needs to be heated to 880-920℃ in the furnace, but after forming, the temperature of the steel sheet is only around 100℃. If the steel sheet is directly quenched after heating, the liquid zinc on the surface faces the risk of liquid metal brittleness cracking. During the pre-cooling process of zinc-based coated steel sheet, if it is directly exposed to air for cooling, the air medium cannot guarantee the cooling rate of different areas of the steel sheet, resulting in uneven cooling of the entire steel sheet. This still poses a risk of liquid metal brittleness during the subsequent quenching and forming process.

[0004] Chinese patent CN106825177A discloses a hot stamping forming method and equipment for galvanized steel sheets. The method provides a hot stamping forming method and equipment for galvanized steel sheets, where the galvanized steel sheet includes a steel sheet body and a galvanized layer. Before hot stamping, a heat-absorbing layer is sprayed onto the surface of the galvanized steel sheet, uniformly covering the galvanized layer. The main steps are as follows: (1) uncoiling the steel coil; (2) blanking the slab; (3) coating with the heat-absorbing layer; (4) heating and stamping; (5) pressure holding and quenching. However, this method still cannot avoid the risk of brittle cracking of liquid metal.

[0005] Therefore, it is extremely important to develop a pre-cooling forming process that can achieve uniform temperature control and remove the surface oxide layer. Summary of the Invention

[0006] To address the shortcomings of existing technologies, the present invention aims to provide a hot forming method for zinc-based coated steel sheets, as well as the coated steel sheet, hot-formed components, and hot-formed system. This method aims to uniformly control the forming temperature of the coated steel sheet components, effectively preventing brittle cracking of the liquid metal, and removing the surface oxide layer facilitates subsequent coating processes. The zinc-based coated hot-formed steel components exhibit excellent corrosion resistance and coating performance.

[0007] The objective of this invention is achieved as follows:

[0008] The present invention provides a hot forming method for zinc-based coated steel sheets, comprising the following steps:

[0009] S1: Heat the zinc-based coated steel sheet to achieve complete austenitization. The heating temperature is 800-905℃, and the heating time is 3-10 minutes. If the temperature is too low, the steel sheet will not be fully austenitized; if the temperature is too high, exceeding the evaporation point of zinc, it will cause the zinc-based coating to evaporate; if the heating time is less than 3 minutes, austenitization will be insufficient; if the heating time exceeds 10 minutes, the zinc-based coating will be extensively oxidized, the austenite grains will be coarse, and the Fe-Zn intermetallic compounds with good corrosion resistance will completely disappear and transform into the α-Fe(Zn) phase.

[0010] S2: The heated zinc-based coated steel sheet is air-cooled to 750-780℃ in order to eliminate or minimize the liquid phase in the zinc-based coating.

[0011] S3: High-pressure jet cooling is used to further cool the air-cooled zinc-based coated steel sheet to 500-700℃, while simultaneously cleaning the oxide layer on the coating surface. The jet pressure is 0.1-1.0 MPa. If the temperature is too low, the steel sheet cannot maintain its austenitization state; if the temperature is too high, it will cause liquid phase embrittlement of the metal, and the steel sheet surface will be severely oxidized, which is not conducive to improving surface quality. The reason for using high-temperature gas is to ensure uniform and consistent cooling. The purpose of using high-pressure gas is to clean the oxide layer on the zinc-based coating surface, which can reduce or even eliminate the subsequent sandblasting process, saving costs and improving efficiency.

[0012] S4: The cooled zinc-based coated steel sheet is transferred to the stamping forming device for final forming; the downward pressure on the steel sheet during forming is 80-400kN; the steel sheet is cooled to 80-150℃ simultaneously during forming. This ensures full contact between the die and the steel sheet, guaranteeing thorough and uniform quenching. The stamping forming device has a cooling function, allowing the zinc-based coated steel sheet to cool to 80-150℃ during forming, simultaneously completing "quenching + forming"; cooling to this temperature aims to induce self-baking in the steel part, improving its plasticity and toughness, while also using its own heat to dry surface moisture, reducing holding time and improving stamping efficiency.

[0013] Furthermore, the medium for jet cooling is one of high-temperature steam, high-temperature water mist, high-temperature air, and high-temperature nitrogen; the high-temperature steam is pure water steam.

[0014] Furthermore, during the jet cooling process, the high-temperature steam temperature is 100-150℃ and the jet pressure is 0.1-1.0MPa; the high-temperature water mist temperature is 90-100℃ and the jet pressure is 0.1-1.0MPa; the high-temperature air and high-temperature nitrogen temperatures are 100-200℃ and the jet pressure is 0.1-1.0MPa.

[0015] The second technical solution of the present invention provides a hot forming system for a hot forming method of zinc-based coated steel sheet, including an induction heating device and a stamping forming device; the induction heating device and the stamping forming device are further sequentially included with a clamping and transferring device, an air cooling device, and a clamping and transferring device.

[0016] The induction heating device is used to heat the zinc-based coated steel sheet to an austenitic state.

[0017] The clamping and transferring device is used to transfer zinc-based coated steel sheets into the jet cooling device.

[0018] The jet cooling device includes a nozzle and a water storage tank. The nozzle is connected to an external jet medium through a pipe and the jet pressure is controlled by a valve for the pre-cooling process of the zinc-based coated steel sheet. The water storage tank is placed below the nozzle to store the liquid generated during the cooling process. A clamping and transfer device is used to transfer the zinc-based coated steel sheet to a stamping and forming device. The stamping and forming device is used to stamp the zinc-based coated steel sheet into its final shape.

[0019] The jet cooling device is the core device of the thermoforming method of the present invention. The jet medium is placed in a gas storage tank and connected to the nozzle through pipes and valves. The jet pressure is controlled by the valves for the pre-cooling process of the zinc-based coated steel sheet. The clamping and transfer device is used to transfer the zinc-based coated steel sheet to the stamping forming device. The stamping forming device is used to stamp the zinc-based coated steel sheet to the final shape.

[0020] The third technical solution of the present invention provides a coated steel sheet for a hot forming method of zinc-based coated steel sheet, comprising a steel sheet substrate and a coating.

[0021] The chemical composition range of the steel plate matrix includes: C: 0.05-0.42wt%, Si: 0.05-0.55wt%, Mn: 0.5-3.5wt%, P≤0.02wt%, S≤0.02wt%, Al: 0.02-1.20%, Nb: 0.02-0.15wt%, V: 0.05-0.15wt%, Ti: 0.02-0.10wt%, Cr≤0.8wt%, Mo≤0.5wt%, B: 0.001-0.005wt%, with the balance being Fe.

[0022] The rationale for the compositional design of the steel plate matrix in this invention is as follows:

[0023] C: 0.05%-0.42wt%. C, as the main alloying element, contributes the most to the strength of quenched martensitic steel, providing strength and expanding the austenite phase region to improve the strength of martensite. If the C content is below 0.05wt%, the strength level requirements cannot be met. If the content is too high, the steel will have excessively high strength, but the toughness and weldability will decrease.

[0024] Si: 0.05%–0.55 wt%. Si primarily inhibits the formation of cementite, ensuring the presence of austenite. Simultaneously, silicon can exist at the interface between the steel substrate and the coating, slowing the diffusion of Zn from the coating into the steel substrate and reducing the rate at which Fe atoms in the steel substrate form Fe-Zn alloys with the coating elements, thus lowering the liquid phase brittleness of hot-formed steel with zinc-based coatings. Furthermore, Si can improve the hardenability of the steel and strengthen the steel substrate. A Si content below 0.05% cannot achieve the above effects, while a silicon content above 0.55% will cause selective oxidation on the surface during the continuous annealing process before hot-dip galvanizing, forming silicon oxide or silicon-manganese composite oxides, affecting the hot-dip galvanizing performance.

[0025] Mn: 0.5%-3.5wt%. The main function of Mn is to expand the austenite phase region, allowing zinc-based coated hot-formed steel sheets to be hot-stamped at lower temperatures and to obtain a martensitic structure; it also improves the strength of the steel matrix through solid solution strengthening, enhances the hardenability of the steel, refines the grains, and improves the toughness of the steel; if the Mn content is less than 0.5%, the austenite phase region of the steel is too small to meet the requirements of low-temperature hot stamping; if the content is higher than 3.50%, selective oxidation will occur on the surface during the continuous annealing process before hot-dip coating, forming manganese oxide or silicon-manganese composite oxides, which will affect the hot-dip coating performance.

[0026] Al: 0.02%–1.20%. The addition of Al can inhibit the formation of cementite, similar to the effect of Si, and can reduce the deterioration of hot-dip galvanizing performance caused by Si, Mn and other elements. If the Al content is below 0.02%, it will not have a good deoxidation effect, and if the content is above 1.20%, it will cause problems such as nozzle turbulence in the continuous casting process, and increase costs.

[0027] Nb: 0.02-0.15wt%, V: 0.05-0.15wt%, Ti: 0.02-0.10wt%. The addition of Ti, V, and Nb can form fine, dispersed precipitates such as TiN, TiC, NbC, and VC in the steel, which can form hydrogen traps during service, improving the steel's resistance to delayed fracture. Furthermore, the addition of Nb strengthens the steel matrix and refines the grain size. Ti can improve hardenability.

[0028] Cr ≤ 0.8 wt%. Cr is added to ensure hardenability. During continuous annealing, Cr migrates to the surface of the steel plate due to selective oxidation, accumulating there. Due to the solute drag effect, it can slow down the erosion of the steel matrix grain boundaries by liquid Zn, reducing liquid phase brittleness. Cr levels above 0.8% will increase hardenability, affect the stable existence of austenite at lower temperatures, worsen hot-dip galvanizing performance, and increase the cost of the steel.

[0029] Mo ≤ 0.5 wt%. The addition of Mo strengthens the steel matrix and refines the grain size.

[0030] B: 0.001-0.005wt%. B element is added to ensure hardenability. The addition of B can improve the grain boundary strength of the steel. B accumulates at the grain boundaries, reducing the local enrichment of H at the grain boundaries, decreasing the tendency for hydrogen-induced cracking, improving the toughness of the steel, and simultaneously improving the hardenability of the steel.

[0031] Furthermore, the chemical composition of the coating ranges from 0.1 to 1.0 wt.% Al, with the balance being Zn. The coating weight on the steel plate surface is 60-240 g / m². 2 .

[0032] The coating contains a certain amount of Al, which forms an Al₂O₃ protective film on the surface during heating and heat preservation. This reduces the oxidation of Zn in the coating and improves the adhesion between the coating and the steel substrate. The coating weight on the steel plate surface is 60-240 g / m². 2 If the coating is too thin, the corrosion resistance will be insufficient; if the coating is too thick, an excessively thick α-Fe(Zn) phase layer will be formed, reducing the strength of the steel plate. Within the target weight range, it can provide good corrosion resistance while controlling the α-Fe(Zn) phase layer within a good range, thus providing good toughness without reducing the strength of the steel plate.

[0033] Furthermore, the coating type also includes one of GI coating and GA coating.

[0034] This invention also provides a zinc-based coated steel sheet component, which is manufactured from the aforementioned zinc-based coated steel sheet using the thermoforming method and thermoforming apparatus provided by this invention. The coating structure of the component, from the surface to the steel substrate, consists of: a surface oxide layer, an Fe-Zn intermetallic compound layer, an α-Fe(Zn) phase layer, and a martensitic phase layer.

[0035] Furthermore, within the time and temperature range specified in this invention, the zinc-based coating structure from the surface to the steel substrate consists of: a surface oxide layer, an Fe-Zn intermetallic compound layer, an α-Fe(Zn) phase layer, and a martensitic phase layer. The coating surface is an extremely thin oxide film with a thickness of 0.1–2 μm; beneath the oxide film is the Fe-Zn intermetallic compound, whose thickness varies between 3 μm and 25 μm depending on the coating thickness and the hot-forming process; below the Fe-Zn intermetallic compound is the α-Fe(Zn) phase, with a thickness between 5 μm and 20 μm; below the α-Fe(Zn) phase is the martensitic steel substrate. Both the Fe-Zn intermetallic compound and the α-Fe(Zn) phase exhibit excellent corrosion resistance and coating properties, thus resulting in superior corrosion resistance and coating performance for the steel plate components.

[0036] The beneficial effects of this invention are as follows:

[0037] 1. The thermoforming apparatus and thermoforming method for coated steel sheet parts provided by the present invention prevent cracking caused by the brittleness of liquid metal on the surface of coated steel sheet by the uniform cooling effect of high temperature spray medium; when the temperature of steel sheet decreases, the liquid zinc coating on the surface of steel sheet is converted to a semi-solid state, thus preventing cracking caused by the brittleness of liquid metal; under the high temperature spray medium mode, slight pressure can remove the thin oxide layer on the surface of steel sheet.

[0038] 2. The hot forming method for zinc-based coated steel sheet parts provided by the present invention has good surface quality after forming and will not produce defects such as mottled spots or color difference caused by uneven cooling.

[0039] 3. The hot forming method for zinc-based coated steel sheet parts provided by this invention has a wide range of forming strengths, capable of forming high-strength parts in the range of 500-2000 MPa. Zinc-based coated hot-formed steel parts possess excellent corrosion resistance and coating performance.

[0040] 4. The hot forming method for zinc-based coated steel sheet parts provided by the present invention is characterized by its diversified selection of spraying media, high operability, and convenient implementation.

[0041] 5. The zinc-based coated hot-formed steel of the present invention ensures the feasibility of the low-temperature quenching forming process by adjusting the composition of the steel plate matrix. That is, the steel plate is pre-cooled to 500-650℃ from the heating temperature before quenching and forming. This can ensure the strength of the steel plate after forming and prevent the occurrence of liquid metal brittleness. Attached Figure Description

[0042] Figure 1 is a schematic diagram of the hot forming system of the hot forming method for zinc-based coated steel sheet parts according to the present invention. In Figure 1:

[0043] 1-Induction heating device; 2-Robotic arm gripping and transfer device; 3-Condensate tank; 4-Cooling nozzle; 5-Robotic arm gripping and transfer device; 6-Pressing device. Detailed Implementation

[0044] The present invention will be further illustrated below through examples.

[0045] A method for hot forming zinc-based coated steel sheet includes the following steps:

[0046] Step 1: Place the zinc-based coated steel sheet in an induction heating furnace and heat it to achieve a fully austenitic state. The heating temperature is 800-905℃ and the heating time is 3-10 minutes.

[0047] If the temperature is too low, the austenitization of the steel plate will be incomplete; if the temperature is too high, exceeding the evaporation point of zinc, it will cause the zinc-based coating to evaporate; if the heating time is less than 3 minutes, the austenitization will be insufficient; if the heating time exceeds 10 minutes, the zinc-based coating will be oxidized in large quantities, the austenite grains will be coarse, and the Fe-Zn intermetallic compounds with good corrosion resistance will completely disappear and transform into the α-Fe(Zn) phase.

[0048] Step 2: Air cool the zinc-based coated steel sheet to 750-780℃;

[0049] The aim is to eliminate or minimize the control of the liquid phase in zinc-based coatings.

[0050] Step 3: Use high-pressure jet cooling to further cool the zinc-based coated steel sheet to 500-700℃, while cleaning the oxide layer on the surface of the zinc-based coating; the jet pressure is 0.1~1.0MPa.

[0051] Step 4: Transfer the cooled zinc-based coated steel sheet to a stamping forming device for final forming. The downward pressure on the steel sheet during the forming process is 80-400 kN; the steel sheet is cooled to 80-150°C during forming.

[0052] Furthermore, the jet cooling medium is one of high-temperature steam, high-temperature water mist, high-temperature air, and high-temperature nitrogen; the high-temperature steam is pure water steam.

[0053] Furthermore, the steam temperature in the jet cooling process is 100-150℃, and the jet pressure is 0.1-1.0MPa; the high-temperature water mist temperature is 90-100℃, and the jet pressure is 0.1-1.0MPa; the high-temperature air and high-temperature nitrogen temperatures are 100-200℃, and the jet pressure is 0.1-1.0MPa.

[0054] A hot forming system for a hot forming method of zinc-based coated steel sheet includes an induction heating device 1 and a stamping forming device 6. The induction heating device 1 and the stamping forming device 6 are further sequentially connected by a clamping and transferring device 2, a jet cooling device, and a clamping and transferring device 5.

[0055] The induction heating device 1 is used to heat the zinc-based coated steel sheet to an austenitic state, including but not limited to electromagnetic induction heaters, resistance induction heaters, and infrared induction heaters.

[0056] The clamping and transferring device 2 is used to transfer the zinc-based coated steel sheet to the jet cooling device.

[0057] The jet cooling device includes a nozzle 4 and a water storage tank 3. The nozzle 4 is connected to an external jet medium through a pipe and the jet pressure is controlled by a valve for the pre-cooling process of zinc-based coated steel plates. The water storage tank 3 is placed below the nozzle 4 and is used to store the liquid generated during the cooling process.

[0058] The clamping and transferring device 5 is used to transfer the zinc-based coated steel sheet to the stamping and forming device 6.

[0059] The clamping and transfer devices 2 and 5 of this application employ robotic arms.

[0060] The stamping forming apparatus 6 is used to stamp zinc-based coated steel sheets into their final shape. The stamping forming apparatus 6 described in this application includes a hot stamping die with a cooling function and a stamping machine.

[0061] A coated steel sheet for a hot forming method of zinc-based coated steel sheet includes a steel sheet substrate and a coating. The chemical composition range of the steel sheet substrate includes: C: 0.05-0.42wt%, Si: 0.05-0.55wt%, Mn: 0.5-3.5wt%, P≤0.02wt%, S≤0.02wt%, Al: 0.02-1.20%, Nb: 0.02-0.15wt%, V: 0.05-0.15wt%, Ti: 0.02-0.10wt%, Cr≤0.8wt%, Mo≤0.5wt%, B: 0.001-0.005wt%, with the balance being Fe. The chemical composition range of the coating is: 0.1-1.0wt.% Al, with the balance being Zn. The coating weight on the steel sheet surface is 60-240 g / m². 2 .

[0062] A zinc-based coated steel plate component made from the above-mentioned steel plate, wherein the coating structure of the component, from the surface to the steel substrate, is as follows: surface oxide layer, Fe-Zn intermetallic compound layer, α-Fe(Zn) phase layer, and martensitic phase layer.

[0063] Furthermore, the surface oxide layer is an extremely thin oxide film with a thickness of 0.1–2 μm; the Fe-Zn intermetallic compound layer has a thickness of 3 μm–25 μm; and the α-Fe(Zn) phase layer has a thickness of 5 μm–20 μm.

[0064] The heating temperature and heating time of the zinc-based coated steel sheet of this invention are shown in Table 1, the various setting parameters of the hot water rinsing section are shown in Table 2, the various setting parameters of the stamping section are shown in Table 3, and the parameters of the drying process section are shown in Table 4.

[0065] Table 1. Aluminum content and coating weight in zinc-based coated steel sheets

[0066] Table 2 Heating Temperature and Heating Time for Zinc-Based Coated Steel Sheets

[0067] Table 3 Parameter settings for zinc-based coated steel sheets in the spraying and cooling process section

[0068] Table 4 Parameter settings for zinc-based coated steel sheets in the quenching and forming process section

[0069] Table 5 Chemical composition of the substrate in zinc-based coated steel sheets

[0070] Table 6 Thickness of each coating layer in zinc-based coated steel sheet components

[0071] Table 7 Performance of Components After Forming from Zinc-Based Coated Steel Sheets

[0072] As can be seen from the above, the hot forming method for zinc-based coated steel sheet parts provided by this invention has a wide range of forming strengths, capable of forming high-strength parts in the range of 500-2000 MPa. Zinc-based coated hot-formed steel parts possess excellent corrosion resistance and coating performance. This invention prevents cracking caused by the brittleness of the liquid metal on the surface of the zinc-based coated steel sheet through the uniform controlled cooling effect of the high-temperature water flow; the flushing pressure in the rinsing mode can remove the thin oxide layer on the surface of the steel sheet, which helps to ensure the surface quality of the parts.

[0073] To illustrate the present invention, the present invention has been appropriately and sufficiently described above through embodiments. The above embodiments are only for illustrating the present invention and are not intended to limit the present invention. Those skilled in the art can make various changes and modifications without departing from the spirit and scope of the present invention. Any modifications, equivalent substitutions, improvements, etc., should be included within the protection scope of the present invention. The patent protection scope of the present invention should be defined by the claims.

Claims

1. A method for hot forming zinc-based coated steel sheet, characterized in that, Includes the following steps: S1: Heat the zinc-based coated steel sheet to achieve a fully austenitic state. The heating temperature is 800-905℃ and the heating time is 3-10 minutes. S2: Air cool the heated zinc-based coated steel sheet to 750-780℃; S3: High-pressure jet cooling is used to further cool the air-cooled zinc-based coated steel sheet to 500-700℃, while cleaning the oxide layer on the coating surface. The jet pressure is 0.1-1.0MPa. S4: The cooled zinc-based coated steel sheet is then finally shaped; The downward pressure on the steel plate during the forming process is 80-400 kN; the steel plate is cooled to 80-150°C during forming.

2. The hot forming method for zinc-based coated steel sheet according to claim 1, characterized in that, The medium for jet cooling is one of high-temperature steam, high-temperature water mist, high-temperature air, or high-temperature nitrogen; the high-temperature steam is pure water steam.

3. The hot forming method for a zinc-based coated steel sheet according to claim 2, characterized in that, The jet cooling process involves high-temperature steam at 100–150°C, high-temperature water mist at 90–100°C, and high-temperature air and nitrogen at 100–200°C.

4. A hot forming system for the hot forming method of zinc-based coated steel sheet according to claim 1, comprising an induction heating device (1) and a stamping forming device (6), characterized in that, Between the induction heating device (1) and the stamping forming device (6), there are also sequentially included a clamping and transferring device (2), a jet cooling device, and a clamping and transferring device (5). The induction heating device (1) is used to heat the zinc-based coated steel sheet to an austenitic state; The clamping and transferring device (2) is used to transfer the zinc-based coated steel sheet into the jet cooling device; The jet cooling device includes a nozzle (4) and a water storage tank (3). The nozzle (4) is connected to an external jet medium through a pipe and the jet pressure is controlled by a valve for the pre-cooling process of the zinc-based coated steel sheet. The water storage tank (3) is placed below the nozzle (4) and is used to store the liquid generated during the cooling process. The clamping and transfer device (5) is used to transfer the zinc-based coated steel sheet to the stamping forming device (6). The stamping forming device (6) is used to stamp the zinc-based coated steel sheet into its final shape.

5. A zinc-based coated steel sheet, characterized in that, A hot forming method applicable to zinc-based coated steel sheets as described in any one of claims 1 to 3, comprising a steel sheet substrate and a coating, wherein the chemical composition of the steel sheet substrate, by mass percentage, consists of the following components: C: 0.05% to 0.42%, Si: 0.05% to 0.55%, Mn: 0.5% to 3.5%, P ≤ 0.02%, S ≤ 0.02%, Al: 0.02% to 1.20%, Nb: 0.02% to 0.15%, V: 0.05% to 0.15%, Ti: 0.02% to 0.10%, Cr ≤ 0.8%, Mo ≤ 0.5%, B: 0.001% to 0.005%, with the balance being Fe.

6. The zinc-based coated steel sheet according to claim 5, characterized in that, The chemical composition of the coating ranges from 0.1 wt.% to 1.0 wt.% Al, with the balance being Zn; the coating weight on the steel plate surface is 60–240 g / m². 2 .

7. The zinc-based coated steel sheet according to claim 5, characterized in that, The coating types also include one of GI coating and GA coating.

8. A zinc-based coated steel sheet component, characterized in that, The zinc-based coated steel sheet according to claims 5-7 is prepared by the method described in claims 1-3. The coating structure of the component, from the surface to the steel substrate, is as follows: surface oxide layer, Fe-Zn intermetallic compound layer, α-Fe(Zn) phase layer, and martensitic phase layer.

9. A zinc-based coated steel sheet component according to claim 8, characterized in that, The surface oxide layer is an extremely thin oxide film with a thickness of 0.1–2 μm; the Fe-Zn intermetallic compound layer has a thickness of 3–25 μm; and the α-Fe(Zn) phase layer has a thickness of 5–20 μm.

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