Steel sheet substrate and steel sheet with pre-coated layer, and methods for manufacturing the same, hot-stamping formed component and method for manufacturing the same, and automotive structural component

Abstract

The present invention provides a steel sheet substrate, a steel sheet having a pre-plating layer and a method for manufacturing the same, a hot stamping formed member and a method for manufacturing the same, and an automobile structural member. The steel sheet substrate comprises 0.29 to 0.42 wt% C, 0.50 to 0.90 wt% Si, 0.30 to 0.70 wt% Mn, 0.10 wt% or less P, 0.10 wt% or less S, 0.01 to 0.40 wt% Cr, 0.001 to 0.01 wt% B, 0.10 to 0.40 wt% Al, 0.002 to 0.005 wt% Mg, 0.10 to 0.30 wt% Cu, 0.05 to 0.20 wt% V, 0.10 wt% or less impurities and excess Fe. The steel plate substrate of the present application satisfies the requirements for a lightweight vehicle body while simultaneously satisfying high strength requirements and possessing toughness and delayed crack resistance.

Description

Technology Field

[0001] The present application relates to the field of automotive thermoforming parts, specifically to a steel sheet substrate, a steel sheet having a pre-plated layer and a method for manufacturing the same, a hot stamping formed member and a method for manufacturing the same, and an automotive structural member. Background Technology

[0003] Ultra-high-strength hot stamping processes are increasingly being applied to the design and manufacture of automotive components. However, generally, an increase in steel sheet strength is accompanied by a decrease in plasticity and toughness. Consequently, in automotive applications, hot-stamped components are drawing the attention of engineers due to issues related to insufficient toughness and delayed cracking. For example, some hot-stamped components develop brittle cracks during storage, processing, transportation, or welding after the hot-stamping process, leading to the scrapping of parts or even entire car bodies and increasing production costs. Even more serious is that delayed cracking in some hot-stamped components occurs only after vehicle assembly is complete, increasing potential safety risks during vehicle operation. Therefore, it is crucial to ensure that hot-stamped components possess sufficient toughness and resistance to delayed cracking during use, particularly when tensile strength exceeds 1800 MPa.

[0005] The object of the present application is to provide a steel plate substrate, a steel plate having a pre-plated layer and a method for manufacturing the same, a hot stamping formed member and a method for manufacturing the same, and an automobile structural member, which satisfies the requirements for a lightweight vehicle body while simultaneously satisfying high strength requirements and possessing toughness and delayed crack resistance.

[0006] To solve the above technical problem, the first aspect of the present application provides a steel plate substrate, said steel plate substrate comprising 0.29 to 0.42 wt% C, 0.50 to 0.90 wt% Si, 0.30 to 0.70 wt% Mn, 0.10 wt% or less P, 0.10 wt% or less S, 0.01 to 0.40 wt% Cr, 0.001 to 0.01 wt% B, 0.10 to 0.40 wt% Al, 0.002 to 0.005 wt% Mg, 0.10 to 0.30 wt% Cu, 0.05 to 0.20 wt% V, 0.10 wt% or less impurities and excess Fe.

[0007] Optionally, the steel sheet substrate comprises 0.32 to 0.38 wt% C, 0.70 to 0.90 wt% Si, 0.30 to 0.50 wt% Mn, 0.10 wt% or less P, 0.10 wt% or less S, 0.01 to 0.20 wt% Cr, 0.001 to 0.01 wt% B, 0.10 to 0.40 wt% Al, 0.002 to 0.003 wt% Mg, 0.22 to 0.30 wt% Cu, 0.05 to 0.20 wt% V, 0.10 wt% or less impurities and excess Fe.

[0008] Optionally, the total content of Si and Cr in the steel plate substrate is 0.7 wt% or more.

[0009] Optionally, Ms of the steel plate substrate calculated according to the following equation (1) satisfies Ms≥335, and

[0010] Ms=500-320×[C]-50×[Mn]-30×[Cr]-5×([Cu]+[Si]), equation (1),

[0011] In Equation (1), [C] represents the C content (weight%) in the steel plate substrate; [Mn] represents the Mn content (weight%) in the steel plate substrate; [Cr] represents the Cr content (weight%) in the steel plate substrate; [Cu] represents the Cu content (weight%) in the steel plate substrate; and [Si] represents the Si content (weight%) in the steel plate substrate.

[0012] Optionally, Ms of the steel plate substrate satisfies Ms≥345.

[0013] A second aspect of the present application provides a method for manufacturing a steel sheet having a pre-plated layer, and

[0014] S1, a step of obtaining a first product by performing an annealing treatment on a steel plate substrate according to the first aspect of the present application; and

[0015] S2, a step of performing a molten plating treatment in a plating solution after cooling the first product; is included.

[0016] Optionally, in step S1, the conditions of the annealing treatment include an annealing temperature of 780°C to 830°C, a dew point of -30°C to -20°C, and a soaking time of 25 s to 35 s.

[0017] Optionally, in step S2, the plating solution comprises 9 to 12 wt% Si, 2 to 3 wt% Fe, 0.10 wt% or less of impurities and excess Al;

[0018] The conditions of the above molten plating treatment include conditions in which, after cooling, the temperature of the first product is 600℃ to 680℃, the temperature of the plating solution is 650℃ to 700℃, and the molten plating time is 2s to 15s;

[0019] The thickness of the plating layer obtained by the above molten plating treatment is 6 μm to 16 μm.

[0020] A third aspect of the present application provides a steel plate having a pre-plated layer manufactured according to the method of the second aspect of the present application.

[0021] A fourth aspect of the present application provides a method for manufacturing a hot stamping molded member, and

[0022] The method includes the step of performing a hot stamping treatment on a steel plate having a preliminary plating layer according to the third aspect of the present application.

[0023] Optionally, the conditions of the hot stamping process include a heating temperature of 880°C to 940°C, a heating time of 180 s to 240 s, a thermoforming temperature of 680°C to 720°C, a pressure holding time of 8 s to 10 s, a cooling rate after hot stamping of 40°C / s to 60°C / s, and a demolding temperature of 200°C or lower.

[0024] The fifth aspect of the present application provides a hot stamping molded member manufactured according to the method of the fourth aspect of the present application.

[0025] Optionally, the yield strength of the hot stamping formed member is 1250 MPa or more, the tensile strength is 2000 MPa or more, the elongation is 5% or more, and the VDA is 40° or more.

[0026] The sixth aspect of the present application provides an automobile structural member and includes a hot stamping formed member according to the fifth aspect of the present application.

[0027] Through the above technical solution, the present application provides a steel plate substrate, a steel plate having a pre-plating layer and a method for manufacturing the same, a hot stamping formed member and a method for manufacturing the same, and an automotive structural member. The steel plate substrate is a dislocation-structured martensite substrate. It not only prevents the formation of a large number of fine twin martensite structures in twin martensite but also prevents the problem of reduced toughness of twin martensite caused by interference with dislocations and severe crystal lattice distortion. Consequently, the steel plate substrate can possess high strength, excellent toughness, and delayed crack resistance. By manufacturing a hot stamping formed member using the steel plate substrate provided in the present application, it is possible to possess high strength, sufficient toughness, and delayed crack resistance, and to exhibit excellent performance for application in automotive structural members.

[0028] Other features and advantages of the present application will be described in detail in the specific embodiments described below. Brief explanation of the drawing

[0030] The attached drawings provide further understanding of the present application, constitute part of the description of the invention, and are used to interpret the present application together with the specific embodiments below, and do not constitute limitations to the present application. Figure 1 is a photograph of the dislocation structure martensite microstructure of a hot stamping steel sheet manufactured in Example 1 of the present application. FIG. 2 is a stress-strain curve of hot-stamped steel sheets manufactured in Examples 1, 2, and 9 of the present application. FIG. 3 is a load-displacement curve of hot stamped steel sheets manufactured in Examples 1, 2, and 9 of the present application. Specific details for implementing the invention

[0031] Hereinafter, specific embodiments of the present application will be described in detail with reference to the attached drawings. It should be understood that the specific embodiments described herein are used merely to explain and interpret the present application and are not intended to limit the application.

[0032] A first aspect of the present application provides a steel sheet substrate, said steel sheet substrate comprising 0.29 to 0.42 wt% C, 0.50 to 0.90 wt% Si, 0.30 to 0.70 wt% Mn, 0.10 wt% or less P, 0.10 wt% or less S, 0.01 to 0.40 wt% Cr, 0.001 to 0.01 wt% B, 0.10 to 0.40 wt% Al, 0.002 to 0.005 wt% Mg, 0.10 to 0.30 wt% Cu, 0.05 to 0.20 wt% V, 0.10 wt% or less impurities and excess Fe.

[0033] The present application provides a steel plate substrate, wherein the steel plate substrate is a dislocation structure martensite substrate. By preventing the formation of a large number of fine twin martensite structures, as well as preventing the problem of reduced toughness of twin martensite caused by interference with dislocations and severe crystal lattice distortion, the steel plate substrate can possess high strength, excellent toughness, and delayed crack resistance. By manufacturing a hot stamping formed member using the steel plate substrate provided in the present application, high strength, sufficient toughness, and delayed crack resistance can be achieved, and excellent performance can be demonstrated for application to automotive structural members.

[0034] According to the present application, C is a cost-effective element for improving steel strength. However, if the C content is excessive, while strength may increase, it may also promote the formation of twin martensite and further reduce the structural toughness of the steel sheet produced. Therefore, in the present application, the C content is controlled within the range of 0.29 to 0.42 weight% so that the steel sheet substrate can possess both strength and toughness.

[0035] According to the present application, to address the decrease in toughness caused by high C content, the Ms temperature (martensite phase transformation start temperature) of the steel sheet substrate is increased. The higher the Ms temperature, the more pronounced the automatic tempering effect of the produced martensite. Tempering of martensite can remove or reduce internal stress, and quenched steel members generally exhibit high hardness but show excessive brittleness and poor plasticity. The steel sheet substrate provided in the present application reduces brittleness and improves plasticity and toughness through automatic tempering after hot stamping, thereby alleviating high stress caused by martensite formation and improving the safety and reliability of the member during use. Therefore, the present application achieves a synergistic effect by controlling the content of Mn, Cr, Cu, and Si, further increases the Ms temperature of the steel sheet substrate, and exerts an automatic tempering effect of the steel sheet substrate, thereby simplifying the process without additional tempering treatment.

[0036] According to the present application, by adding a small amount (0.002 to 0.005 wt%) of Mg to a steel plate substrate, on the one hand, it contributes to grain refinement, and on the other hand, it deforms the shape of inclusions into a rounder form, thereby improving the ductility and toughness of the steel. As rounder and more uniformly distributed MgS and MgO particles are formed, the amount of unfavorable FeS is reduced, and the ductility and toughness of the steel are improved.

[0037] According to the present application, by adding 0.10 to 0.30 weight% of Cu to a steel plate substrate, the austenite region is expanded and the precipitation of a copper-rich phase is promoted, and hydrogen atoms can be captured with the high hydrogen capture bonding energy of the copper-rich phase, thereby reducing the risk of hydrogen embrittlement and further improving the toughness of the steel.

[0038] In one preferred embodiment, the steel sheet substrate comprises 0.32 to 0.38 wt% C, 0.70 to 0.90 wt% Si, 0.30 to 0.50 wt% Mn, 0.10 wt% or less P, 0.10 wt% or less S, 0.01 to 0.20 wt% Cr, 0.001 to 0.01 wt% B, 0.10 to 0.40 wt% Al, 0.002 to 0.003 wt% Mg, 0.22 to 0.30 wt% Cu, 0.05 to 0.20 wt% V, 0.10 wt% or less impurities and excess Fe. A steel sheet substrate having the content of the preferred components provided in this embodiment may have higher strength and toughness.

[0039] In one preferred embodiment, the total content of Si and Cr in the steel sheet substrate is 0.7 weight% or more, preferably 1 weight% or more. The total content of Si and Cr controlled within the range of this embodiment can increase the strength and toughness of the steel sheet substrate.

[0040] In one preferred embodiment, the Ms of the steel plate substrate calculated according to the following equation (1) satisfies Ms≥335, and

[0041] Ms=500-320×[C]-50×[Mn]-30×[Cr]-5×([Cu]+[Si]), equation (1),

[0042] In Equation (1), [C] represents the C content (weight%) in the steel plate substrate; [Mn] represents the Mn content (weight%) in the steel plate substrate; [Cr] represents the Cr content (weight%) in the steel plate substrate; [Cu] represents the Cu content (weight%) in the steel plate substrate; and [Si] represents the Si content (weight%) in the steel plate substrate. The inventors of the present application have discovered through research that when the Ms temperature calculated according to Equation (1) using the content of each component in the steel plate substrate is 335°C or higher, the steel plate substrate has a better self-tempering effect during the hot stamping process. As the Ms temperature increases, the self-tempering performance of the steel plate substrate improves accordingly, which helps to obtain a hot stamping steel plate having high strength and excellent plasticity and toughness.

[0043] In one preferred embodiment, the Ms of the steel plate substrate satisfies Ms≥345. In this embodiment, a steel plate substrate having a preferred Ms temperature can further improve the strength and toughness of the steel plate substrate after hot stamping.

[0044] In one specific embodiment, the steel plate substrate can be manufactured by a conventional process in the art.

[0045] A second aspect of the present application provides a method for manufacturing a steel sheet having a pre-plated layer, comprising the following steps S1 and S2.

[0046] S1, an annealing treatment is performed on a steel plate substrate according to the first aspect of the present application to obtain a first product.

[0047] S2, after cooling the first product, a molten plating treatment is performed in a plating solution.

[0048] The present application provides a method for manufacturing a steel sheet having a pre-plated layer. This method first obtains a first product having an initial low-carbon region by using an annealing treatment, which is advantageous for subsequent plating processes. Subsequently, a molten plating treatment is performed to introduce a plating layer having oxidation resistance and corrosion resistance onto the surface of a steel sheet substrate.

[0049] In one embodiment, before performing an annealing treatment in step S1, the method further comprises the following.

[0050] The steel plate substrate is pre-degreased, electrolytically degreased, brushed, rinsed, and dried in a washing section to remove more than 90% of the oil and iron particles from the surface of the steel plate substrate; subsequently, an annealing treatment is performed on the washed steel plate substrate, wherein the annealing treatment can be performed in a vertical continuous annealing furnace.

[0051] In one embodiment, in step S1, the conditions of the annealing treatment include an annealing temperature of 780°C to 830°C, a dew point of -30°C to -20°C, and a soaking time of 25 s to 35 s. Preferably, the annealing temperature is 790°C to 820°C, the dew point is -28°C to -22°C, and the soaking time is 28 s to 32 s. According to the process conditions of the present embodiment, an annealing treatment performed under particularly preferred process conditions helps to obtain a hot stamping steel sheet having higher strength and toughness.

[0052] In one embodiment, at step S2, the plating solution comprises 9 to 12 wt% Si, 2 to 3 wt% Fe, 0.10 wt% or less of impurities and excess Al. Preferably, the plating solution comprises 10 to 11 wt% Si, 2.5 to 3.0 wt% Fe, 0.10 wt% or less of impurities and excess Al. A steel plate substrate using the plating solution provided in this embodiment has excellent corrosion resistance.

[0053] In one embodiment, the conditions of the molten plating process include conditions in which the temperature of the first product after cooling is 600°C to 680°C, the temperature of the plating solution is 650°C to 700°C, and the molten plating time is 2 s to 15 s; preferably, conditions in which the temperature of the first product after cooling is 620°C to 670°C, the temperature of the plating solution is 660°C to 690°C, and the molten plating time is 5 s to 10 s. The first product may be cooled by a conventional rapid cooling and / or slow cooling method. According to the process conditions of the present embodiment, performing the molten plating process under particularly preferred process conditions may help improve the plating quality.

[0054] In one specific embodiment, after step S2, the following steps S3 and S4 are further included.

[0055] S3, after the steel plate substrate leaves the plating solution, and before the plating solution solidifies on at least one surface of the steel plate substrate, the excess plating solution on the at least one surface is removed by wiping with a gas knife to control the thickness of the plating layer on the at least one surface, wherein a gas knife can be a conventional process in the art.

[0056] S4, after coming out of the loop, skin pass rolling and tension leveling are performed on the strip steel (i.e., steel plate substrate), then a passivation solution is coated through a roll coater, the strip steel coated with the passivation solution is dried with hot air, then the strip steel is subjected to surface quality inspection on a horizontal inspection table and a vertical inspection table, then enters an oiling machine to be coated with oil, then shears the strip steel by a flying shear to obtain a sample, enters a winding machine, and after packaging, is stored in a warehouse.

[0057] In one specific embodiment, the thickness of the plating layer obtained by the molten plating treatment is 6 μm to 16 μm, and it may have excellent oxidation resistance and corrosion resistance.

[0058] A third aspect of the present application provides a steel plate having a pre-plated layer manufactured by the method according to the second aspect of the present application.

[0059] A fourth aspect of the present application provides a method for manufacturing a hot stamping molded member, said method,

[0060] The method includes the step of performing a hot stamping treatment on a steel plate having a preliminary plating layer according to the third aspect of the present application.

[0061] In one preferred embodiment, the conditions of the hot stamping process include a heating temperature of 880°C to 940°C, preferably 900°C to 930°C, a heating time of 180 s to 240 s, a thermoforming temperature of 680°C to 720°C, a pressure holding time of 8 s to 10 s, a cooling rate after hot stamping of 40°C / s to 60°C / s, and a demolding temperature of 200°C or lower. When the hot stamping process is performed according to the process conditions provided in this embodiment, it helps to improve the performance of the hot stamped steel sheet.

[0062] According to the fifth aspect of the present application, a hot stamping molded member manufactured by the method according to the fourth aspect of the present application is provided.

[0063] In one specific embodiment, the hot stamping formed member has a yield strength ≥ 1250 MPa, a tensile strength ≥ 2000 MPa, an elongation ≥ 5%, and a VDA ≥ 40°; preferably, the yield strength ≥ 1350 MPa, a tensile strength ≥ 2100 MPa, an elongation ≥ 6%, and a VDA ≥ 45°.

[0064] In one specific embodiment, the thickness of the plating layer of the hot stamping molded member is 10 μm to 25 μm, and it may have excellent oxidation resistance and corrosion resistance.

[0065] The sixth aspect of the present application provides an automobile structural member and includes a hot stamping formed member according to the fifth aspect of the present application.

[0066] In one specific embodiment, the vehicle structural member includes, but is not limited to, safety structural members such as left / right collision prevention bars (beams) of the front / rear doors, front / rear bumpers, A-pillar reinforcing panels, B-pillar reinforcing panels, C-pillar reinforcing panels, intermediate channels, and roof reinforcing beams. It may also be applied to the manufacture of battery enclosures for new energy vehicles.

[0067] The present application will be explained in more detail through the following examples. All materials used in the examples are commercially available.

[0068] Images of the martensitic structure of hot-stamped steel sheets are obtained using a ZEISS-LAB A1.MAT microscope (Germany).

[0070] Example 1

[0071] (1) A steel plate substrate with a composition listed in Table 1 is pre-degreased, electrolytically degreased, brushed, rinsed, and dried in a washing section to remove more than 90% of the oil and iron particles from the surface of the steel plate substrate, and then the washed steel plate substrate is fed into a vertical continuous annealing furnace to preheat and heat to the required annealing temperature of 800°C for the strip steel, and the dew point is -22°C and the soaking time is 30 seconds, so that the steel plate with the pre-plating layer has an initial low-carbon region and the first product is obtained.

[0072] (2) After the first product is cooled slowly or rapidly to a temperature of 670°C, it is placed in a plating solution, the temperature of the plating solution is 680°C and the melt plating time is 10 seconds, and the plating solution contains 10.4 wt% Si, 2.6 wt% Fe, 0.10 wt% or less of impurities and excess Al.

[0073] (3) Cooling: After the steel plate substrate leaves the plating solution, and before the plating solution solidifies on at least one surface of the steel plate substrate, the excess plating solution on the at least one surface is removed by wiping with a gas knife to control the thickness of the plating layer on the at least one surface, thereby controlling the thickness of the plating layer to within the range of 6 μm to 16 μm.

[0074] (4) Oil Coating: After coming out of the loop, skin pass rolling and tension leveling are performed on the strip steel, then a passivation solution is coated through a roll coater, and the strip steel coated with the passivation solution is dried with hot air. Then, the strip steel is subjected to surface quality inspection on a horizontal inspection table and a vertical inspection table, then enters an oiling machine to be coated with oil, then shears the strip steel by a flying shear to obtain a sample, and then enters a winding machine. Then, (the steel plate with the pre-plating layer) is packaged and stored in a warehouse.

[0075] (5) Hot stamping treatment: Hot stamping treatment is performed on a steel plate having a pre-plated layer, and the conditions include a heating temperature of 920°C, a heating time of 230 s, a thermoforming temperature of 700°C, a pressure holding time of 9 s, a cooling rate after hot stamping of 50°C / s, and a demolding temperature of 180°C. A hot stamped formed member is obtained. The thickness of the plating layer is within the range of 10 μm to 25 μm.

[0076] A micrograph of the martensite structure of a hot stamping steel sheet manufactured according to the present embodiment is shown in FIG. 1. As shown in FIG. 1, the martensite of the hot stamping steel sheet manufactured using the steel sheet substrate provided in the present application is a dislocation structure martensite structure.

[0078] Examples 2~9

[0079] Refer to the manufacturing method of Example 1, except that the difference from Example 1 is that the content of each component of the steel plate substrate used is as shown in Table 1, and the other process is the same as Example 1.

[0081] Comparative Examples 1~5

[0082] Refer to the manufacturing method of Example 1, except that the difference from Example 1 is that the content of each component of the steel plate substrate used is as shown in Table 1, and the other process is the same as Example 1.

[0083] Table 1

[0084]

[0085] In Table 1, the unit of all metal component data is “weight%”; the excess of the steel plate substrate in each example and comparative example is Fe; component content marked with “-” indicates that the corresponding component was not added; and the unit of Ms is “°C”.

[0087] Test example

[0088] Tests for tensile strength, elongation, and maximum bending angle were performed on untempered hot-stamped flat plate members obtained in accordance with the GBT228.1 Room Temperature Tensile Test Standard and the VDA-238 Three-Point Bending Test Standard. Here, the VDA angle was calculated according to the calculation method in Appendix D of VDA 238-100:2020. The data for the hot-stamped steel plates obtained in each example and comparative example are the average values ​​of the test results from the three groups to minimize experimental error. The test results are shown in Table 2 below.

[0089] Table 2

[0090]

[0091] Based on the data in Table 2, the following conclusions can be drawn.

[0092] The steel substrates used in Comparative Examples 1 to 4 all do not contain Mg and Cu, and the Si and Mn content of the steel substrates in Comparative Example 1 and Examples 3 to 4 are all outside the range provided in this application, and their Ms temperature is also outside the range provided in this application. The C, Si, and Mn content of the steel substrate in Comparative Example 2 are all outside the range provided in this application. The Mg and Cu content of the steel substrate used in Comparative Example 5 is outside the range provided in this application; and the hot stamping steel sheets produced in Comparative Examples 1 to 2 and 4 to 5 have high elongation and VDA angle, but have relatively low yield strength and tensile strength, for example, the tensile strength did not reach 2000 MPa. It can be seen that the strength performance, elongation, and VDA angle of the hot stamping steel sheet produced in Comparative Example 3 are relatively low, and that the hot stamping steel sheet produced using the steel sheet substrates provided in Comparative Examples 1 to 5 could not achieve comprehensive performance combining high strength and excellent plasticity and toughness. Compared to Comparative Examples 1 to 5, the hot stamping steel sheet produced using the steel sheet substrates provided in the present application in Examples 1 to 9 can achieve higher strength performance (yield strength ≥ 1250 MPa, tensile strength ≥ 2000 MPa) and excellent toughness and plasticity (elongation ≥ 5%, VDA ≥ 40°).

[0093] Comparing Example 1 and Example 2, it can be seen that the Ms temperature of the steel plate substrate provided in Example 1 is within the preferred range (Ms temperature ≥ 345℃) provided in this application, and that the hot stamping steel plate produced in Example 1 has higher strength performance, higher elongation, and a larger VDA angle.

[0094] When comparing Examples 3 to 8 with Example 9, the content of C, Si, Mn, Cr, Mg, and Cu in the steel plate substrate used in Example 9 all fell outside the preferred range provided in this application, namely 0.32 to 0.38 wt% C, 0.70 to 0.90 wt% Si, 0.30 to 0.50 wt% Mn, 0.01 to 0.20 wt% Cr, 0.002 to 0.003 wt% Mg, and 0.22 to 0.30 wt% Cu, and in each of the steel plate substrates used in Examples 3 to 8, the content of any one of the components of C, Si, Mn, Cr, Mg, and Cu fell outside the preferred range provided in this application. Specifically, the C component in the steel substrate used in Example 3, the Si component in the steel substrate used in Example 4, the Mn component in the steel substrate used in Example 5, the Cr component in the steel substrate used in Example 6, the Mg component in the steel substrate used in Example 7, and the Cu component in the steel substrate used in Example 8 were outside the preferred range provided in this application, namely 0.32 to 0.38 wt% C, 0.70 to 0.90 wt% Si, 0.30 to 0.50 wt% Mn, 0.01 to 0.20 wt% Cr, 0.002 to 0.003 wt% Mg, and 0.22 to 0.30 wt% Cu. Compared to the hot stamping steel sheet produced in Example 9, the hot stamping steel sheets produced in Examples 3 to 8 have higher strength performance, higher elongation, and a larger VDA angle.

[0095] Further comparing Examples 3 to 8 with Example 1, the composition of the steel sheet substrate used in Example 1 is within the preferred range provided in this application, namely 0.32 to 0.38 wt% C, 0.70 to 0.90 wt% Si, 0.30 to 0.50 wt% Mn, 0.10 wt% or less P, 0.10 wt% or less S, 0.01 to 0.20 wt% Cr, 0.001 to 0.01 wt% B, 0.10 to 0.40 wt% Al, 0.002 to 0.003 wt% Mg, 0.22 to 0.30 wt% Cu, 0.05 to 0.20 wt% V, 0.10 wt% or less impurities, and excess Fe, and the hot stamping steel sheet produced in Example 1 has higher strength performance, higher elongation, and a larger VDA angle. It is equipped.

[0096] The stress-strain curves of the hot stamping steel sheets produced in Examples 1 to 2 and Example 9 are shown in FIG. 2, and from FIG. 2, it can be seen that the hot stamping steel sheet produced from the steel sheet substrate of Example 1 has higher strength while maintaining excellent elongation.

[0097] The load-displacement curves of the hot stamping steel sheets manufactured in Examples 1 to 2 and Example 9 are shown in FIG. 3, and from FIG. 3, it can be seen that the hot stamping steel sheet manufactured from the steel sheet substrate of Example 1 has a better bending angle, that is, has better toughness.

[0098] Preferred embodiments of the present application have been described in detail with reference to the accompanying drawings, but the present application is not limited to the specific details of the embodiments. Within the scope of the technical concept of the present application, various simple modifications may be made to the technical means of the present application, and all such simple modifications fall within the scope of protection of the present application.

[0099] It should also be noted that each specific technical feature described in the specific embodiments above may be combined in any suitable manner where not contradictory, and to avoid unnecessary repetition, this application does not describe various possible combination forms.

[0100] Furthermore, various embodiments of the present application may be combined at will without conflict with the spirit of the present application, and such combinations are also deemed to be as disclosed in the present application.

Claims

Claim 1 A steel plate substrate, wherein the steel plate substrate comprises 0.29 to 0.42 wt% C, 0.50 to 0.90 wt% Si, 0.30 to 0.70 wt% Mn, 0.10 wt% or less P, 0.10 wt% or less S, 0.01 to 0.40 wt% Cr, 0.001 to 0.01 wt% B, 0.10 to 0.40 wt% Al, 0.002 to 0.005 wt% Mg, 0.10 to 0.30 wt% Cu, 0.05 to 0.20 wt% V, 0.10 wt% or less impurities and excess Fe. Claim 2 A steel plate substrate according to claim 1, characterized in that the steel plate substrate comprises 0.32~0.38 wt% C, 0.70~0.90 wt% Si, 0.30~0.50 wt% Mn, 0.10 wt% or less P, 0.10 wt% or less S, 0.01~0.20 wt% Cr, 0.001~0.01 wt% B, 0.10~0.40 wt% Al, 0.002~0.003 wt% Mg, 0.22~0.30 wt% Cu, 0.05~0.20 wt% V, 0.10 wt% or less impurities and excess Fe. Claim 3 A steel plate substrate according to claim 1, characterized in that the total content of Si and Cr in the steel plate substrate is 0.7 weight% or more. Claim 4 A steel plate substrate according to claim 1, wherein Ms of the steel plate substrate calculated according to the following formula (1) satisfies Ms ≥ 335, Ms = 500 - 320 × [C] - 50 × [Mn] - 30 × [Cr] - 5 × ([Cu] + [Si]), formula (1), wherein [C] represents the C content (weight%) in the steel plate substrate; [Mn] represents the Mn content (weight%) in the steel plate substrate; [Cr] represents the Cr content (weight%) in the steel plate substrate; [Cu] represents the Cu content (weight%) in the steel plate substrate; and [Si] represents the Si content (weight%) in the steel plate substrate. Claim 5 A steel plate substrate characterized in that, in paragraph 4, Ms of the steel plate substrate satisfies Ms≥345. Claim 6 A method for manufacturing a steel plate having a pre-plated layer, comprising: S1, a step of performing an annealing treatment on a steel plate substrate according to any one of claims 1 to 5 to obtain a first product; and S2, a step of performing a molten plating treatment in a plating solution after cooling the first product; characterized in that it comprises a steel plate having a pre-plated layer. Claim 7 A method for manufacturing a steel sheet having a pre-plated layer, characterized in that, in step S1 of claim 6, the conditions of the annealing treatment include an annealing temperature of 780℃ to 830℃, a dew point of -30℃ to -20℃, and a soaking time of 25s to 35s. Claim 8 A method for manufacturing a steel sheet having a pre-plated layer, characterized in that, in step S2 of claim 6, the plating solution comprises 9 to 12 wt% Si, 2 to 3 wt% Fe, 0.10 wt% or less of impurities and excess Al; the conditions of the molten plating treatment include conditions in which the temperature of the first product after cooling is 600°C to 680°C, the temperature of the plating solution is 650°C to 700°C, and the molten plating time is 2 s to 15 s; and the thickness of the plating layer obtained by the molten plating treatment is 6 μm to 16 μm. Claim 9 A steel plate having a pre-plating layer manufactured according to the method of paragraph 6. Claim 10 A method for manufacturing a hot stamping formed member, characterized by including the step of performing a hot stamping treatment on a steel plate having a preliminary plating layer according to claim 9. Claim 11 A method for manufacturing a hot stamped molded member according to claim 10, wherein the conditions of the hot stamping process include a heating temperature of 880℃ to 940℃, a heating time of 180s to 240s, a thermoforming temperature of 680℃ to 720℃, a pressure holding time of 8s to 10s, a cooling rate after hot stamping of 40℃ / s to 60℃ / s, and a demolding temperature of 200℃ or lower. Claim 12 A hot stamping molded member manufactured according to the method of claim 10. Claim 13 A hot stamping formed member according to claim 12, characterized in that the yield strength of the hot stamping formed member is 1250 MPa, the tensile strength is 2000 MPa or more, the elongation is 5% or more, and the VDA is 40° or more. Claim 14 An automobile structural member characterized by including the hot stamping formed member of claim 12.

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