Steel plate base body, pre-plated steel plate and preparation method thereof, hot stamping forming component and preparation method thereof, and automobile structural part

Abstract

The invention relates to a steel plate base body, a pre-plated steel plate and a preparation method thereof, a hot stamping forming component and a preparation method thereof and an automobile structural part. On the basis of the total weight of the steel plate base body, the steel plate base body comprises 0.42%-0.55% by weight of C, 0.40%-0.90% by weight of Si, 0.50%-1.20% by weight of Mn, 0.10% by weight or less of P, 0.10% by weight or less of S, 0.20%-0.50% by weight of Al, 0.0025%-0.01% by weight of B, 1.05%-2.55% by weight of W, 0.40%-1.50% by weight of Cr, 0.10% by weight or less of impurities and the balance Fe. The steel plate base body can meet the light weight requirement of a vehicle body, the hot stamping forming component has ultrahigh strength and sufficient toughness, and the delayed cracking risk is reduced.

Description

Technical Field

[0001] The present invention relates to the field of automotive hot - formed components, and particularly to a steel plate substrate, a pre - plated steel plate and its preparation method, a hot stamping forming component and its preparation method, and an automotive structural component. Background Art

[0002] In recent years, the ultra - high - strength hot stamping forming process has been increasingly applied to the design and manufacturing of automotive components. However, generally, the increase in the strength of steel plates leads to a decrease in plasticity and toughness. Therefore, in the application in the vehicle field, the problems caused by insufficient toughness and delayed cracking of hot stamping forming components have increasingly attracted the attention of technicians. For example, in the actual production process, brittle cracking often occurs in hot stamping forming components during placement, processing, transportation, or welding after hot stamping, resulting in the scrapping of parts or even the entire vehicle body, thus increasing the production cost. More seriously, some hot stamping forming components undergo delayed cracking only after the vehicle assembly is completed, thus increasing the safety hazards during vehicle operation. Therefore, when using hot stamping forming components, it is crucial to ensure both strength and toughness of the hot stamping forming components. Summary of the Invention

[0003] The object of the present disclosure is to provide a steel plate substrate, a pre - plated steel plate and its preparation method, a hot stamping forming component and its preparation method, and an automotive structural component, which can meet the lightweight requirements of the vehicle body, and the hot stamping forming component has both ultra - high strength and sufficient toughness, reducing the risk of delayed cracking.

[0004] To solve the above - mentioned technical problems, in the first aspect of the present disclosure, a steel plate substrate is provided. Based on the total weight of the steel plate substrate, the steel plate substrate includes 0.42 - 0.55 wt% of C, 0.40 - 0.90 wt% of Si, 0.50 - 1.20 wt% of Mn, P below 0.10 wt%, S below 0.10 wt%, 0.20 - 0.50 wt% of Al, 0.0025 - 0.01 wt% of B, 1.05 - 2.55 wt% of W, 0.40 - 1.50 wt% of Cr, impurities below 0.10 wt%, and the balance of Fe.

[0005] The present disclosure provides a steel plate substrate. By controlling the content of material C and the addition and control of other alloy element contents, especially the control of the contents of Si, Mn, Al, and the addition of W and B, an ultra - high - strength hot stamping forming component with high resistance to hydrogen embrittlement and delayed cracking is obtained, which has both ultra - high strength and sufficient toughness and has good application effects in automotive structural components.

[0006] In one embodiment, the steel plate substrate comprises 0.45 to 0.51 wt% of C, 0.40 to 0.90 wt% of Si, 0.50 to 1.20 wt% of Mn, less than 0.10 wt% of P, less than 0.10 wt% of S, 0.20 to 0.50 wt% of Al, 0.0025 to 0.01 wt% of B, 1.25 to 2.15 wt% of W, 0.55 to 1.35 wt% of Cr, less than 0.10 wt% of impurities and the balance of Fe. The steel plate substrate with the preferred component contents provided by this embodiment can produce hot stamping components with better strength and toughness.

[0007] In one embodiment, in the steel plate substrate, the total content of W + Cr is 1.60 to 3.70 wt%, preferably 1.95 to 3.35 wt%. By controlling the total content of W + Cr in the steel plate substrate within the range of this embodiment, especially within the preferred range, the toughness of the steel plate substrate can be further improved, and then the strength and delayed cracking performance of the hot stamping component can be improved.

[0008] In one embodiment, in the steel plate substrate, (W + Cr) / C is 3 to 10, preferably 4.5 to 6.5. By controlling the content relationship of the three components of W, Cr and C in the steel plate substrate within the range of this embodiment, especially within the preferred range, it is beneficial to control the effect of generating Cr3W3C in the matrix, and then the effect of reducing the C content in the matrix is better, so as to improve the formation of martensite and the toughness of the steel plate substrate.

[0009] The second aspect of the present disclosure provides a method for preparing a pre-coated steel plate, comprising the following steps: S1. Annealing the steel plate substrate described in the first aspect of the present disclosure to obtain a first product; S2. After cooling the first product, performing hot dip plating treatment in a plating solution.

[0010] The present disclosure provides a method for preparing a pre-coated steel plate. First, through annealing treatment, a first product with an initial low-carbon region can be obtained, which is beneficial to subsequent coating and other processes; then, through hot dip plating treatment, a coating is introduced onto the surface of the steel plate substrate, which has antioxidant and anti-corrosion effects.

[0011] In one embodiment, in step S1, the conditions of the annealing treatment include: the annealing temperature is 780 to 830 °C, the dew point is -20 °C to -3 °C, and the soaking time is 25 to 35 s. According to the process conditions in this embodiment, performing the annealing treatment is beneficial to obtaining a hot stamping steel plate with higher strength and toughness.

[0012] In one embodiment, in step S2, the plating solution comprises 9-12% by weight of Si, 2-3% by weight of Fe, impurities below 0.10% by weight, and the balance Al; using the plating solution provided by this embodiment has a better corrosion resistance effect; The conditions of the hot dip plating treatment include: the temperature of the first product after cooling is 600-680°C, the temperature of the plating solution is 650-700°C, and the hot dip plating time is 2-15 s; The thickness of the coating layer obtained by the hot dip plating treatment is 6-16 μm. Conducting the hot dip plating treatment under the process conditions in this embodiment is beneficial to improving the coating quality.

[0013] The third aspect of the present disclosure provides a pre-coated steel sheet prepared by the method described in the second aspect of the present disclosure.

[0014] The fourth aspect of the present disclosure provides a method for preparing a hot stamping formed component, comprising the following steps: Performing hot stamping treatment on the pre-coated steel sheet described in the third aspect of the present disclosure.

[0015] In one embodiment, the conditions of the hot stamping treatment include: the heating temperature is 800-920°C, the heating time is 180-240 s, the hot forming temperature is 680-720°C, the pressure holding time is 8-10 s, the cooling rate after hot stamping is 40-60°C / s, and the die exit temperature ≤ 200°C. Conducting the hot stamping treatment according to the process conditions provided by this embodiment is beneficial to improving the performance of the hot stamping steel sheet.

[0016] The fifth aspect of the present disclosure provides a hot stamping formed component prepared by the method described in the fourth aspect of the present disclosure.

[0017] In one embodiment, the yield strength of the hot stamping formed component ≥ 1300 MPa, the tensile strength ≥ 2300 MPa, and the elongation ≥ 5%; preferably, the yield strength ≥ 1550 MPa, the tensile strength ≥ 2400 MPa, and the elongation ≥ 5.5%. The hot stamping formed component provided by the present disclosure can simultaneously have high yield strength, tensile strength, and elongation, and has excellent comprehensive performance.

[0018] The sixth aspect of the present disclosure provides an automotive structural component, comprising the hot stamping formed component described in the fifth aspect of the present disclosure, which can effectively improve the performance of the automotive structural component.

[0019] Other features and advantages of the present disclosure will be described in detail in the subsequent specific embodiment part. Description of the Drawings

[0020] The accompanying drawings are used to provide a further understanding of the present disclosure and form a part of the specification. Together with the following specific embodiments, they are used to explain the present disclosure, but do not constitute a limitation to the present disclosure. In the accompanying drawings: Figure 1 It is the stress-strain curve diagram of the hot stamping forming member obtained in Example 1 of the present disclosure; Figure 2 It is the stress-strain curve diagram of the hot stamping forming member obtained in Comparative Example 1 of the present disclosure. Specific Embodiments

[0021] The following further details the specific embodiments of the present disclosure with reference to the accompanying drawings. It should be understood that the specific embodiments described herein are only used to illustrate and explain the present disclosure, and are not used to limit the present disclosure.

[0022] The first aspect of the present disclosure provides a steel plate substrate. Based on the total weight of the steel plate substrate, the steel plate substrate includes 0.42 - 0.55 wt% of C (carbon), 0.40 - 0.90 wt% of Si (silicon), 0.50 - 1.20 wt% of Mn (manganese), 0.10 wt% or less of P (phosphorus), 0.10 wt% or less of S (sulfur), 0.20 - 0.50 wt% of Al (aluminum), 0.0025 - 0.01 wt% of B (boron), 1.05 - 2.55 wt% of W (tungsten), 0.40 - 1.50 wt% of Cr (chromium), 0.10 wt% or less of impurities, and the balance of Fe (iron).

[0023] The present disclosure provides a steel plate substrate. By controlling the addition and control of the C content of the material and the contents of other alloying elements, especially the control of the contents of Si, Mn, and Al and the addition of W and B, an ultra-high-strength hot stamping forming member with high resistance to hydrogen embrittlement and delayed cracking can be obtained, and it has both ultra-high strength and sufficient toughness, and has good application effects in automotive structural parts.

[0024] According to the present disclosure, C is the most cost-effective element for improving the strength of steel. By controlling the C content within the range of 0.42 - 0.55 wt%, higher strength can be obtained.

[0025] According to the present disclosure, on the one hand, Si is dissolved in the matrix and has the effect of improving the matrix strength; on the other hand, it can also be used as a deoxidizer during the steelmaking process, so Si with a content of more than 0.10 wt% needs to be added. However, more Si causes different degrees of grain boundary oxidation and decarburization on the surface of the steel plate at different positions during the cooling process after hot rolling coiling of the steel coil, affecting the pickling effect of the steel coil and ultimately affecting the surface quality of the finished product. By adding 0.40 - 0.90 wt% of Si in the present disclosure, a steel plate substrate with better performance can be obtained.

[0026] The inventors of the present disclosure have found that existing steel plate substrates fail to well control the martensitic transformation properties. This not only leads to the formation of brittle twinned martensite, which is not conducive to subsequent processing, but also has a significant impact on the toughness and delayed cracking performance of hot stamping steels and their formed components. Moreover, when the C content is too high, twinned martensite is formed instead of lath martensite with better toughness. In the present disclosure, by adding W + Cr in combination, and then reacting with C in the substrate to form Cr3W3C, the C content in the substrate is reduced, and then lath martensite is formed; and Cr3W3C is uniformly dispersed in the substrate, which can strengthen the substrate and hinder dislocation movement, thereby obtaining good strength and toughness.

[0027] In a preferred embodiment, the steel plate substrate comprises 0.45 - 0.51 wt% of C, 0.40 - 0.90 wt% of Si, 0.50 - 1.20 wt% of Mn, less than 0.10 wt% of P, less than 0.10 wt% of S, 0.20 - 0.50 wt% of Al, 0.0025 - 0.01 wt% of B, 1.25 - 2.15 wt% of W, 0.55 - 1.35 wt% of Cr, less than 0.10 wt% of impurities and the balance of Fe. The steel plate substrate with the preferred component contents provided by this embodiment can produce hot stamping formed components with better strength and toughness.

[0028] In an embodiment, in the steel plate substrate, the total content of W + Cr is 1.60 - 3.70 wt%, including but not limited to 1.6 wt%, 1.8 wt%, 2.0 wt%, 2.2 wt%, 2.4 wt%, 2.6 wt%, 2.8 wt%, 3.0 wt%, 3.2 wt%, 3.4 wt%, 3.6 wt%, 3.7 wt% and the ranges formed by any two values; preferably 1.95 - 3.35 wt%. By controlling the total content of W + Cr in the steel plate substrate within the range of this embodiment, especially within the preferred range, the toughness of the steel plate substrate can be further improved, and then the strength and delayed cracking performance of the hot stamping component can be improved.

[0029] In a preferred embodiment, in the steel plate substrate, (W + Cr) / C is 3 - 10, including but not limited to 3, 4, 5, 6, 7, 8, 9, 10 and the ranges formed by any two values; preferably 4.5 - 6.5. The inventors of the present disclosure have found through experimental research that by controlling the content relationship of the three components of W, Cr and C in the steel plate substrate within the range of this embodiment, especially within the preferred range, it is beneficial to control the effect of forming Cr3W3C in the substrate, and then the effect of reducing the C content in the substrate is better, so as to improve the formation of martensite and the toughness of the steel plate substrate.

[0030] In the present disclosure, the steel plate substrate can be prepared by conventional processes in the art.

[0031] The second aspect of the present disclosure provides a method for preparing a pre-coated steel plate, comprising the following steps: S1. Annealing the steel plate substrate described in the first aspect of the present disclosure to obtain a first product; S2. After cooling the first product, subject it to hot dip plating treatment in a plating solution.

[0032] The present disclosure provides a method for preparing a pre-coated steel plate. First, through annealing treatment, a first product with an initial low-carbon region can be obtained, which is beneficial to subsequent processes such as coating; then, through hot dip plating treatment, a coating is introduced onto the surface of the steel plate substrate, having antioxidant and anti-corrosion effects.

[0033] In one embodiment, in step S1, before performing the annealing treatment, it further includes: After subjecting the steel plate substrate to pre-degreasing, electrolytic degreasing, brushing, rinsing, and drying in a cleaning section, more than 90% of the oil and iron powder on the surface of the steel plate substrate can be removed; then subject the cleaned steel plate substrate to the annealing treatment; wherein the annealing treatment can be carried out in a vertical continuous annealing furnace.

[0034] In one embodiment, in step S1, the conditions of the annealing treatment include: the annealing temperature is 780 - 830 °C, the dew point is -20 to -3 °C, and the soaking time is 25 - 35 s; preferably, the annealing temperature is 790 - 820 °C, the dew point is -22 to -5 °C, and the soaking time is 28 - 32 s. According to the process conditions in this embodiment, especially according to the preferred process conditions, performing the annealing treatment is beneficial to obtaining a hot stamping steel plate with higher strength and toughness.

[0035] In one embodiment, in step S2, the plating solution includes 9 - 12 wt% of Si, 2 - 3 wt% of Fe, impurities below 0.10 wt%, and the balance is Al; preferably, the plating solution includes 10 - 11 wt% of Si, 2.5 - 3.0 wt% of Fe, impurities below 0.10 wt%, and the balance is A; using the plating solution provided in this embodiment has a better corrosion resistance effect.

[0036] In one embodiment, the conditions of the hot dip plating treatment include: the temperature of the first product after cooling is 600 - 680 °C, the temperature of the plating solution is 650 - 700 °C, and the hot dip plating time is 2 - 15 s; preferably, the temperature of the first product after cooling is 620 - 670 °C, the temperature of the plating solution is 660 - 690 °C, and the hot dip plating time is 5 - 10 s; wherein the first product can be cooled by conventional fast cooling and / or slow cooling methods. According to the process conditions in this embodiment, especially according to the preferred process conditions, performing the hot dip plating treatment is beneficial to improving the coating quality.

[0037] In a specific embodiment, after step S3, the following steps are further included: S3. After the steel plate substrate leaves the plating solution and before the plating solution on at least one surface of the steel plate substrate solidifies, the excess plating solution on the at least one surface is removed by air knife blowing to control the coating thickness on the at least one surface; wherein the air knife can adopt the conventional process in the art; S4. After coming out of the loop, the strip steel (steel plate substrate) is subjected to skin pass rolling and stretch leveling, and then a passivation solution is coated by a roll coater. The strip steel coated with the passivation solution needs to be dried by hot air; then the strip steel enters the horizontal inspection table and the vertical inspection table for surface quality inspection, and then enters an oiling machine for oiling. After slitting and sampling by a flying shear, it enters a coiler; after packaging, it is stored in the warehouse.

[0038] In a specific embodiment, the thickness of the coating obtained by the hot-dip plating treatment is 6-16 μm, which can have good antioxidant and anti-corrosion effects.

[0039] The third aspect of the present disclosure provides a pre-coated steel plate prepared by the method according to the second aspect of the present disclosure.

[0040] The fourth aspect of the present disclosure provides a method for preparing a hot stamping forming member, including the following steps: Performing hot stamping treatment on the pre-coated steel plate according to the third aspect of the present disclosure.

[0041] In a preferred embodiment, the conditions of the hot stamping treatment include: the heating temperature is 800-920 °C, preferably 830-900 °C, the heating time is 180-240 s, the hot forming temperature is 680-720 °C, the holding pressure time is 8-10 s, the cooling rate after hot stamping is 40-60 °C / s, and the die exit temperature is below 200 °C. Performing hot stamping treatment according to the process conditions provided in this embodiment is beneficial to improving the performance of the hot stamping steel plate.

[0042] The fifth aspect of the present disclosure provides a hot stamping forming member prepared by the method according to the fourth aspect of the present disclosure.

[0043] In a specific embodiment, the yield strength of the hot stamping forming member is ≥1300 MPa, the tensile strength is ≥2300 MPa, and the elongation is ≥5%; preferably, the yield strength is ≥1550 MPa, the tensile strength is ≥2400 MPa, and the elongation is ≥5.5%. The hot stamping forming member provided by the present disclosure can simultaneously have high yield strength, tensile strength and elongation, and has excellent comprehensive performance.

[0044] In a specific embodiment, the thickness of the coating of the hot stamping forming member is 10-25 μm, which can have good antioxidant and anti-corrosion effects.

[0045] The sixth aspect of the present disclosure provides an automotive structural member, including the hot stamping forming member described in the fifth aspect of the present disclosure.

[0046] In a specific embodiment, the automotive structural member includes, but is not limited to, safety structural members such as front and rear door left and right anti-collision bars (beams), front and rear bumpers, A-pillar reinforcement plates, B-pillar reinforcement plates, C-pillar reinforcement plates, middle channels, roof reinforcement beams, etc.; it can also be applied to the production of battery packs for new energy vehicles.

[0047] The present disclosure will be further described in detail below through examples. The raw materials used in the examples can all be obtained through commercial channels.

[0048] Example 1 (1) After the steel sheet substrate (the composition of the steel sheet substrate is listed in Table 1) is pre-degreased, electrolytically degreased, brushed, rinsed, and dried in the cleaning section, more than 90% of the oil and iron powder on the surface of the steel sheet substrate can be removed; then the cleaned steel sheet substrate enters a vertical continuous annealing furnace, is preheated, heated to the required strip annealing temperature of 800 °C, the dew point is -10 °C, and soaked for 30 s, so that the pre-coated steel sheet has an initial low-carbon zone, and a first product is obtained; (2) The first product is slowly cooled or quickly cooled to 650 °C and then enters the plating solution. The temperature of the plating solution is 660 °C, and the hot-dip plating time is 8 s; the plating solution includes 10% by weight of Si, 3% by weight of Fe, impurities below 0.10% by weight, and the balance is Al; (3) Cooling: After the steel sheet substrate leaves the plating solution and before the plating solution on at least one surface of the steel sheet substrate solidifies, the excess plating solution on at least one surface is removed by air knife blowing to control the thickness of the plating layer on at least one surface; the thickness of the plating layer is controlled within the range of 6 - 16 μm; (4) Oil coating: After coming out of the loop, the strip is subjected to skin pass and tension leveling, and then a passivation solution is coated by a roll coater. The strip coated with the passivation solution needs to be dried by hot air. Then the strip enters a horizontal inspection table and a vertical inspection table for surface quality inspection, and then enters an oil coating machine for oil coating. After slitting and sampling by a flying shear, it enters a coiler. Then it is packaged and stored in the warehouse (pre-coated steel sheet); (5) Hot stamping treatment: The pre-coated steel sheet is subjected to hot stamping treatment. The hot stamping treatment conditions include: heating temperature of 910 °C, heating time of 210 s, hot forming temperature of 690 °C, pressure holding time of 9 s, cooling rate after hot stamping of 45 °C / s, and die exit temperature of 180 °C. A hot stamping forming member is obtained. The thickness of the plating layer is controlled within the range of 10 - 25 μm.

[0049] Examples 2 - 9 Referring to the preparation method in Example 1, the difference from Example 1 is that the component content of the steel sheet substrate used is as shown in Table 1; the remaining processes are the same as those in Example 1.

[0050] Comparative Examples 1 - 8 Referring to the preparation method in Example 1, the difference from Example 1 is that: the component contents of the steel plate substrate used are shown in Table 1; the remaining processes are the same as those in Example 1.

[0051] Comparative Example 9 Referring to the preparation method in Example 1, the difference from Example 1 is that: the components of the steel plate substrate used include (referring to the component contents in WO2024104279A1): 0.33 wt% of C, 0.15 wt% of Si, 1.27 wt% of Mn, 0.013 wt% of P, 0.009 wt% of S, 0.29 wt% of Al, 0.008 wt% of Nb+Ti (by weight), 0.0025 wt% of B, 0.21 wt% of W (B+W+Nb < 0.22 wt%), 0.28 wt% of Cr, 0.15 wt% of V, and the balance Fe; the remaining processes are the same as those in Example 1.

[0052] Table 1

[0053] In Table 1, the unit of each metal component data is "wt%"; the balance of the steel plate substrate in each example and comparative example is Fe; the component content of "-" means that the component is not added or does not have this data.

[0054] +Nb Test Example 1 Mechanical property test: Tensile strength test and elongation test were carried out on the hot stamping flat die parts obtained from the above examples and comparative examples in accordance with the "GBT228.1 - Room Temperature Tensile Standard"; the final test results were the average of 3 groups of test results to reduce errors.

[0055] The test results are listed in Table 2 below.

[0056] Table 2

[0057] Among them, the stress - strain curves of the hot stamping formed steel plate samples obtained in Example 1 and Comparative Example 1 are as Figures 1 - 2 shown.

[0058] It can be seen from the data in Table 2 that In Comparative Example 1 and Comparative Examples 4-7, W and Cr were not added to the steel plate substrate, and Cr was replaced by Nb or V. The hot stamping formed steel plates made from the steel plate substrates in Comparative Example 1 and Comparative Examples 4-7 had low tensile strength and low yield strength, so their comprehensive properties were poor. The hot stamping formed steel plates made from the steel plate substrates in Examples 1-9 of the present disclosure had significantly improved tensile strength, and could also balance excellent yield strength and elongation, with more excellent comprehensive properties. In Comparative Examples 2-3, the contents of W and Cr in the steel plate substrate exceeded or were lower than the content ranges provided by the present disclosure, and the total content of W+Cr also exceeded or was lower than the range provided by the present disclosure. The yield strength, tensile strength and elongation of the hot stamping formed steel plates made from the steel plate substrates in Comparative Examples 2-3 were all low, and their comprehensive properties were poor. The comprehensive properties of the hot stamping formed steel plates made from the steel plate substrates in Examples 1-9 of the present disclosure were more excellent in terms of tensile strength, yield strength and elongation. In Comparative Example 8, the C content of the steel plate substrate was not within the range provided by the present disclosure. The elongation of the hot stamping formed steel plate made from this steel plate substrate was low, and its comprehensive properties were poor. In Comparative Example 9, the composition of the steel plate substrate was not within the range provided by the present disclosure. Comparing Examples 1-9 with Comparative Example 9, it can be seen that the hot stamping formed steel plates prepared from the steel plate substrates provided by the present disclosure in Examples 1-9 can have higher yield strength, tensile strength and good elongation, and better comprehensive properties. Comparing Example 7 with Examples 8-9, it can be seen that the total content of W+Cr in the steel plate substrate in Example 7 was within the optimized range provided by the present disclosure (1.60-3.70 wt%), and the comprehensive properties of the hot stamping formed steel plate prepared in Example 7 were better. Comparing Example 1 with Example 7, it can be seen that the contents of W, Cr and the total content of W+Cr in the steel plate substrate in Example 1 were within the further preferred range provided by the present disclosure. The hot stamping formed steel plate prepared from the steel plate substrate in Example 1 had higher yield strength, tensile strength and good elongation, and better comprehensive properties. Comparing Examples 4-5 with Example 6, it can be seen that the Cr content in Example 4 was within the preferred range provided by the present disclosure (0.55-1.35 wt%), the W content in Example 5 was within the preferred range provided by the present disclosure (1.25-2.15 wt%), and the total content of W+Cr in the steel plate substrates in Examples 4-5 was within the preferred range provided by the present disclosure (1.95-3.35 wt%). The comprehensive properties of the hot stamping formed steel plates prepared in Examples 4-5 were better. Comparing Example 1 with Examples 4-5, it can be seen that the contents of Cr and W in the steel plate matrix of Example 1, as well as the total content of W+Cr, are all within the preferred ranges provided by the present disclosure. The hot stamping formed steel plate obtained in Example 1 has higher yield strength, tensile strength, and good elongation, and has better comprehensive performance; Comparing Example 1 with Example 2, it can be seen that the total content of W+Cr and the ratio of W+Cr / C in Example 1 are both within the preferred ranges provided by the present disclosure. The hot stamping formed steel plate obtained in Example 1 has higher yield strength, tensile strength, and good elongation, and has better comprehensive performance; Comparing Example 1 with Example 3, it can be seen that the C content in the steel plate matrix of Example 1 is within the preferred range provided by the present disclosure (0.45-0.51 wt%). The hot stamping formed steel plate obtained in Example 1 has higher yield strength, tensile strength, and good elongation, and has better comprehensive performance.

[0059] Test Example 2 This test example is used to illustrate the test results of the delayed cracking performance of the four-point bending specimens of the hot stamping flat die parts (hot stamping formed steel plates) obtained in Example 1, Comparative Example 1, and Comparative Example 9 above.

[0060] The delayed cracking performance of the hot stamping flat die parts obtained in the above examples and comparative examples was evaluated according to "GB / T40403 - Method for Determining the Stress Corrosion Cracking Resistance of Metals by Four-Point Bending Method"; the final test results were the average values of 3 groups of test results to reduce errors. The standard for the delayed cracking performance of the hot stamping parts includes: no cracking in the 300h hydrogen embrittlement test. This test includes the following steps: (1) A rectangular specimen with a cross-sectional size of 15mm×115mm was obtained on the hot stamping formed steel plates obtained in the above examples and comparative examples by laser cutting, and the length direction of the specimen was perpendicular to the rolling direction of the steel plate; (2) Select typical specimens and perform pre-tension on a tensile testing machine to obtain the yield strength of the material in the hot stamping state; (3) Apply prestress loading to the specimen through a four-point bending fixture. In this test example, the prestress σ of 100% of the yield strength obtained in step (2) was selected for the steel plate specimen in the hot stamping state; (4) After the specimen was loaded, it was placed in an air medium at a temperature of 15-30°C to observe whether fracture occurred. There were 3 parallel specimens for each stress level, and if 1 cracked specimen appeared within 300 hours, it was determined to be cracked.

[0061] The test results are listed in Table 3 below.

[0062] Table 3

[0063] It can be seen from the data in Table 3 that: In the delayed cracking performance test, after 300 h of testing, none of the three groups of specimens of the hot stamping formed steel plate obtained in Example 1 fractured; For the three groups of specimens of the hot stamping formed steel plate obtained in Comparative Example 1, fractures occurred before 300 h in the delayed cracking performance test; For the three groups of specimens of the hot stamping formed steel plate obtained in Comparative Example 9, fractures occurred in some of the samples in the delayed cracking performance test, and the fracture time was below 300 h.

[0064] The above test results show that the hot stamping formed components made of the steel matrix provided by the present disclosure have more excellent delayed cracking performance.

[0065] The preferred embodiments of the present disclosure have been described in detail above in conjunction with the accompanying drawings. However, the present disclosure is not limited to the specific details in the above embodiments. Within the scope of the technical concept of the present disclosure, various simple modifications can be made to the technical solutions of the present disclosure, and these simple modifications all fall within the protection scope of the present disclosure.

[0066] In addition, it should be noted that, in the case of no conflict, the various specific technical features described in the above specific embodiments can be combined in any suitable manner. To avoid unnecessary repetition, the present disclosure will not separately describe various possible combination methods.

[0067] In addition, any combination can be made between various different embodiments of the present disclosure, as long as it does not violate the idea of the present disclosure, and it should also be regarded as the content disclosed by the present disclosure.

Claims

1. A steel plate substrate, characterized in that, Based on the total weight of the steel plate substrate, the steel plate substrate comprises 0.42 - 0.55 wt% of C, 0.40 - 0.90 wt% of Si, 0.50 - 1.20 wt% of Mn, P below 0.10 wt%, S below 0.10 wt%, 0.20 - 0.50 wt% of Al, 0.0025 - 0.01 wt% of B, 1.05 - 2.55 wt% of W, 0.40 - 1.50 wt% of Cr, impurities below 0.10 wt% and the balance of Fe.

2. The steel plate substrate according to claim 1, wherein, The steel plate substrate comprises 0.45 - 0.51 wt% of C, 0.40 - 0.90 wt% of Si, 0.50 - 1.20 wt% of Mn, P below 0.10 wt%, S below 0.10 wt%, 0.20 - 0.50 wt% of Al, 0.0025 - 0.01 wt% of B, 1.25 - 2.15 wt% of W, 0.55 - 1.35 wt% of Cr, impurities below 0.10 wt% and the balance of Fe.

3. The steel plate substrate according to claim 1, characterized in that, In the steel plate substrate, the total content of W + Cr is 1.60 - 3.70 wt%.

4. The steel plate substrate according to claim 1, characterized in that, In the steel plate substrate, (W + Cr) / C is 3 - 10.

5. A method for preparing a pre-coated steel sheet, characterized in that, Comprising the following steps: S1. Annealing the steel plate substrate according to any one of claims 1 - 4 to obtain a first product; S2. After cooling the first product, performing hot-dip plating treatment in a plating solution.

6. The method according to claim 5, wherein In step S1, the conditions of the annealing treatment include: the annealing temperature is 780 - 830 °C, the dew point is -20 °C to -3 °C, and the soaking time is 25 - 35 s.

7. The method according to claim 5, characterized in that, In step S2, the plating solution comprises 9 - 12 wt% of Si, 2 - 3 wt% of Fe, impurities below 0.10 wt% and the balance of Al; The conditions of the hot-dip plating treatment include: the temperature of the first product after cooling is 600 - 680 °C, the temperature of the plating solution is 650 - 700 °C, and the hot-dip plating time is 2 - 15 s; The thickness of the coating obtained by the hot-dip plating treatment is 6 - 16 μm.

8. A pre-coated steel plate prepared by the method according to any one of claims 5 - 7.

9. A method for manufacturing a hot stamping formed component, characterized in that, Comprising the following steps: Performing hot stamping treatment on the pre-coated steel plate as claimed in claim 8.

10. The method according to claim 9, characterized in that, The conditions of the hot stamping treatment include: the heating temperature is 800 - 920 °C, the heating time is 180 - 240 s, the hot forming temperature is 680 - 720 °C, the pressure holding time is 8 - 10 s, the cooling rate after hot stamping is 40 - 60 °C / s, and the die exit temperature ≤ 200 °C.

11. A hot stamping formed component prepared by the method according to claim 9 or 10.

12. The hot stamping formed component according to claim 11, characterized in that, The yield strength of the hot stamping formed component is ≥ 1300 MPa, the tensile strength is ≥ 2300 MPa, and the elongation is ≥ 5%.

13. An automotive structural component, characterized in that, Comprising the hot stamping formed component as claimed in claim 11 or 12.

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