Steel plate substrate, pre-plated steel plate and preparation method thereof, hot stamping formed component and preparation method thereof, and automobile structural part

Abstract

A steel plate substrate, a pre-plated steel plate and a method for preparing the same, a hot stamping forming component and a method for preparing the same, and an automobile structural part. The steel plate substrate includes 0.29-0.42 wt% C, 0.50-0.90 wt% Si, 0.30-0.70 wt% Mn, 0.10 wt% or less P, 0.10 wt% or less S, 0.01-0.40 wt% Cr, 0.001-0.01 wt% B, 0.10-0.40 wt% Al, 0.002-0.005 wt% Mg, 0.10-0.30 wt% Cu, 0.05-0.20 wt% V, 0.10 wt% or less impurities and the remainder Fe. The steel plate substrate disclosed in the present invention can meet the high strength requirements and have both sufficient toughness and delayed cracking resistance while meeting the lightweight requirements of the vehicle body.

Description

Technical Field

[0001] The invention relates to the field of automobile hot forming parts, and in particular to a steel plate substrate, a pre-plated steel plate and a preparation method thereof, a hot stamping formed component and a preparation method thereof, and an automobile structural part. Background Art

[0002] Ultra-high-strength hot stamping processes are increasingly being used in the design and manufacturing of automotive components. However, in general, an increase in the strength of steel plates will lead to a decrease in plasticity and toughness. Therefore, in applications in the vehicle field, the problems caused by insufficient toughness and delayed cracking of hot stamped components have increasingly attracted the attention of technicians. For example, some hot stamped components suffer brittle cracking during placement, processing, transportation or welding after hot stamping, resulting in the scrapping of parts or even the entire vehicle body, thereby increasing production costs. More seriously, some hot stamped components only experience delayed cracking after the vehicle is assembled, thereby increasing the safety risks of the vehicle during driving. Therefore, when using hot stamped components, especially when their strength reaches 1800MPa or more, it is crucial to ensure that the hot stamped components have sufficient toughness and delayed cracking resistance. Summary of the invention

[0003] The purpose of the present disclosure is to provide a steel plate substrate, a pre-plated steel plate and a preparation method thereof, a hot stamping formed component and a preparation method thereof, and an automobile structural part, which can meet the high strength requirements and have both sufficient toughness and delayed cracking resistance while meeting the lightweight demand of the vehicle body.

[0004] In order to solve the above technical problems, the first aspect of the present disclosure provides a steel plate substrate, which includes 0.29~0.42 weight % of C, 0.50~0.90 weight % of Si, 0.30~0.70 weight % of Mn, 0.10 weight % or less of P, 0.10 weight % or less of S, 0.01~0.40 weight % of Cr, 0.001~0.01 weight % of B, 0.10~0.40 weight % of Al, 0.002~0.005 weight % of Mg, 0.10~0.30 weight % of Cu, 0.05~0.20 weight % of V, less than 0.10 weight % of impurities and the remainder of Fe.

[0005] Optionally, the steel plate matrix includes 0.32-0.38 wt % C, 0.70-0.90 wt % Si, 0.30-0.50 wt % Mn, less than 0.10 wt % P, less than 0.10 wt % 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, less than 0.10 wt % impurities and the remainder Fe.

[0006] Optionally, the total content of Si and Cr in the steel plate matrix is ​​greater than 0.7 wt %.

[0007] Optionally, the Ms of the steel plate substrate calculated according to the following formula (1) is ≥335:

[0008] Ms=500-320×[C]-50×[Mn]-30×[Cr]-5×([Cu]+[Si]), formula (1);

[0009] In formula (1), [C] represents the C content in the steel plate matrix, in weight %; [Mn] represents the Mn content in the steel plate matrix, in weight %; [Cr] represents the Cr content in the steel plate matrix, in weight %; [Cu] represents the Cu content in the steel plate matrix, in weight %; and [Si] represents the Si content in the steel plate matrix, in weight %.

[0010] Optionally, the steel plate substrate has Ms≥345.

[0011] A second aspect of the present disclosure provides a method for preparing a pre-plated steel plate, comprising the following steps:

[0012] S1. annealing the steel plate substrate described in the first aspect of the present disclosure to obtain a first product;

[0013] S2, cooling the first product and then placing it into a plating solution for hot dip plating.

[0014] Optionally, in step S1, the annealing treatment conditions include: annealing temperature of 780-830°C, dew point of -30 to -20°C, and soaking time of 25-35s.

[0015] Optionally, in step S2, the plating solution comprises 9-12 wt% Si, 2-3 wt% Fe, less than 0.10 wt% impurities and the balance Al;

[0016] 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 seconds;

[0017] The thickness of the coating obtained by the hot-dip plating process is 6-16 μm.

[0018] A third aspect of the present disclosure provides a pre-plated steel plate prepared by the method described in the second aspect of the present disclosure.

[0019] A fourth aspect of the present disclosure provides a method for preparing a hot stamping component, comprising the following steps:

[0020] The pre-plated steel sheet according to the third aspect of the present disclosure is subjected to hot stamping treatment.

[0021] Optionally, the conditions of the hot stamping treatment include: heating temperature of 880~940℃, heating time of 180~240s, hot forming temperature of 680~720℃, holding time of 8~10s, cooling rate after hot stamping of 40~60℃ / s, and demolding temperature below 200℃.

[0022] A fifth aspect of the present disclosure provides a hot stamping component prepared by the method described in the fourth aspect of the present disclosure.

[0023] Optionally, the hot stamping formed component has a yield strength ≥1250 MPa, a tensile strength ≥2000 MPa, an elongation ≥5%, and a VDA ≥40°.

[0024] A sixth aspect of the present disclosure provides an automobile structural part, comprising the hot stamping formed component according to the fifth aspect of the present disclosure.

[0025] Through the above technical scheme, the present disclosure provides a steel plate substrate, a pre-plated steel plate and a preparation method thereof, a hot stamping formed component and a preparation method thereof, and an automobile structural part. The steel plate substrate is a dislocation martensitic matrix, which can avoid the formation of a large number of fine twin substructures in the twin martensite, and its hindering effect on dislocations and serious lattice distortion, thereby causing the problem of poor toughness of the twin martensite. The steel plate substrate can have high strength, good toughness, and delayed cracking resistance. The hot stamping formed component prepared from the steel plate substrate provided by the present disclosure can have high strength and both sufficient toughness and delayed cracking resistance, and has a good application effect in automobile structural parts.

[0026] Other features and advantages of the present disclosure will be described in detail in the following detailed description. BRIEF DESCRIPTION OF THE DRAWINGS

[0027] The accompanying drawings are used to provide a further understanding of the present disclosure and constitute 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 of the present disclosure. In the accompanying drawings:

[0028] Figure 1This is a microstructure photograph of dislocation martensite of the hot stamped steel plate prepared in Example 1 of the present disclosure;

[0029] Figure 2 : is the stress-strain curve of the hot stamped steel sheet prepared in Examples 1, 2 and 9 of the present disclosure;

[0030] Figure 3 1 is the load-displacement curve of the hot stamped steel plates prepared in Examples 1, 2 and 9 of the present disclosure. DETAILED DESCRIPTION

[0031] The specific implementation of the present disclosure is described in detail below in conjunction with the accompanying drawings. It should be understood that the specific implementation described herein is only used to illustrate and explain the present disclosure, and is not used to limit the present disclosure.

[0032] A first aspect of the present disclosure provides a steel plate substrate, which includes 0.29~0.42 weight % of C, 0.50~0.90 weight % of Si, 0.30~0.70 weight % of Mn, 0.10 weight % or less of P, 0.10 weight % or less of S, 0.01~0.40 weight % of Cr, 0.001~0.01 weight % of B, 0.10~0.40 weight % of Al, 0.002~0.005 weight % of Mg, 0.10~0.30 weight % of Cu, 0.05~0.20 weight % of V, 0.10 weight % or less of impurities and the balance of Fe.

[0033] The present disclosure provides a steel plate matrix, which is a dislocation martensite matrix, and can avoid the formation of a large number of fine twin substructures in twin martensite, and its hindering effect on dislocations and serious lattice distortion, thereby causing the problem of poor toughness of twin martensite. The steel plate matrix can have high strength, good toughness and delayed cracking resistance. The steel plate matrix provided by the present disclosure is prepared to obtain a hot stamping component, which can have high strength and both sufficient toughness and delayed cracking resistance, and has a good application effect in automotive structural parts.

[0034] According to the present disclosure, C is a cost-effective element for improving the strength of steel, but excessive C content, although it can improve the strength, will also promote the formation of twinned martensite and deteriorate the toughness of the final steel plate structure. Therefore, the present disclosure controls the C content within the range of 0.29~0.42 weight %, so that the steel plate matrix can have both strength and toughness.

[0035] According to the present disclosure, the present disclosure addresses the problem of poor toughness caused by high C content by increasing the Ms temperature (starting temperature of martensitic phase transformation) of the steel plate matrix; the higher the Ms temperature, the more obvious the self-tempering effect of the produced martensite, and martensite tempering can eliminate or reduce internal stress. The steel parts after quenching are usually high in hardness but brittle and poor in plasticity. The steel plate matrix provided by the present disclosure can reduce brittleness, improve plasticity and toughness through self-tempering after hot stamping, making the parts safer and more reliable during use, thereby reducing the high stress caused by the generation of martensite. Therefore, the present disclosure controls the content of Mn, Cr, Cu and Si to exert a synergistic application effect, thereby increasing the Ms temperature of the steel plate matrix, and can exert the self-tempering effect of the steel plate matrix, without the need for additional tempering treatment, and also simplifies the process.

[0036] According to the present disclosure, adding a trace amount (0.002-0.005 wt%) of Mg to the steel plate matrix can refine the grains on the one hand, and change the morphology of inclusions to make them more rounded on the other hand, thereby improving the ductility and toughness of the steel. By forming more rounded and evenly distributed MgS and MgO, the amount of unfavorable FeS is reduced, thereby improving the ductility and toughness of the steel.

[0037] According to the present disclosure, adding 0.10-0.30 wt. % Cu to the steel plate matrix can not only expand the austenite region, but also precipitate a copper-rich phase, which has a high hydrogen trap binding energy and can capture hydrogen, thereby reducing the risk of hydrogen embrittlement and improving toughness.

[0038] In a preferred embodiment, the steel plate matrix includes 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 the remainder Fe. The steel plate matrix having the preferred component contents provided in this embodiment can have higher strength and toughness.

[0039] In a preferred embodiment, the total content of Si and Cr in the steel plate matrix is ​​0.7 wt % or more, preferably 1 wt % or more. By controlling the total content of Si and Cr within the range of this embodiment, the strength and toughness of the steel plate matrix can be improved.

[0040] In a preferred embodiment, the Ms of the steel plate substrate calculated according to the following formula (1) is ≥335:

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

[0042] In formula (1), [C] represents the C content in the steel plate matrix, % by weight; [Mn] represents the Mn content in the steel plate matrix, % by weight; [Cr] represents the Cr content in the steel plate matrix, % by weight; [Cu] represents the Cu content in the steel plate matrix, % by weight; and [Si] represents the Si content in the steel plate matrix, % by weight. The inventors of the present disclosure have found through research that when the Ms temperature obtained by the component content in the steel plate matrix according to formula (1) is above 335°C, the self-tempering effect of the steel plate matrix during hot stamping is better; and as Ms increases, the self-tempering performance of the steel plate matrix is ​​also improved accordingly, which is conducive to obtaining a hot stamping steel plate with high strength and excellent plasticity and toughness.

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

[0044] In a specific implementation manner, the steel plate substrate can be prepared by conventional processes in the art.

[0045] A second aspect of the present disclosure provides a method for preparing a pre-plated steel plate, comprising the following steps:

[0046] S1. annealing the steel plate substrate described in the first aspect of the present disclosure to obtain a first product;

[0047] S2, cooling the first product and then placing it into a plating solution for hot dip plating.

[0048] The present disclosure provides a method for preparing a pre-plated steel plate, which first undergoes annealing treatment to obtain a first product having an initial low-carbon zone, which is beneficial to subsequent coating and other processes; then, a coating is introduced into the surface of the steel plate substrate through hot-dip plating, which has an anti-oxidation and anti-corrosion effect.

[0049] In one embodiment, in step S1, before the annealing treatment is performed, the process further includes:

[0050] After the steel plate substrate 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 plate substrate can be removed; then the cleaned steel plate substrate is subjected to the annealing treatment; wherein the annealing treatment can be carried out in a vertical continuous annealing furnace.

[0051] In one embodiment, in step S1, the annealing conditions include: an annealing temperature of 780 to 830°C, a dew point of -30 to -20°C, and a soaking time of 25 to 35s; preferably, the annealing temperature is 790 to 820°C, the dew point is -28 to -22°C, and the soaking time is 28 to 32s. Annealing according to the process conditions in this embodiment, especially according to the preferred process conditions, is conducive to obtaining a hot stamping steel plate with higher strength and toughness.

[0052] In one embodiment, in step S2, the plating solution includes 9-12 wt% Si, 2-3 wt% Fe, less than 0.10 wt% impurities, and the remainder is Al; preferably, the plating solution includes 10-11 wt% Si, 2.5-3.0 wt% Fe, less than 0.10 wt% impurities, and the remainder is A; the plating solution provided in this embodiment has better corrosion resistance.

[0053] In one embodiment, the conditions for hot-dip plating 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 2~15s; 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 5~10s; wherein the first product can be cooled by conventional fast cooling and / or slow cooling. The process conditions in this embodiment, especially hot-dip plating according to the preferred process conditions, are beneficial to improving the coating quality.

[0054] In a specific implementation manner, after step S3, the method further includes:

[0055] 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, removing excess plating solution on the at least one surface by blowing with an air knife to control the thickness of the coating on the at least one surface; wherein the air knife can adopt conventional processes in the art;

[0056] S4. After coming out of the loop, the strip (steel plate substrate) is smoothed and stretched, and then coated with passivation liquid by a roller coater. The strip coated with passivation liquid needs to be dried by hot air; then the strip enters the horizontal inspection table and the vertical inspection table for surface quality inspection, and then enters the oiler for oiling, and then enters the coiler after slitting and sampling by the flying shear; and is packed and stored.

[0057] In a specific embodiment, the coating obtained by the hot-dip plating process has a thickness of 6 to 16 μm, which can have good anti-oxidation and anti-corrosion effects.

[0058] A third aspect of the present disclosure provides a pre-plated steel plate prepared by the method described in the second aspect of the present disclosure.

[0059] A fourth aspect of the present disclosure provides a method for preparing a hot stamping component, comprising the following steps:

[0060] The pre-plated steel sheet according to the third aspect of the present disclosure is subjected to hot stamping treatment.

[0061] In a preferred embodiment, the conditions of the hot stamping treatment include: a heating temperature of 880-940°C, preferably 900-930°C, a heating time of 180-240s, a hot forming temperature of 680-720°C, a holding time of 8-10s, a cooling rate after hot stamping of 40-60°C / s, and a die-out temperature of less than 200°C. Performing hot stamping treatment according to the process conditions provided in this embodiment is conducive to improving the performance of the hot stamped steel sheet.

[0062] A fifth aspect of the present disclosure provides a hot stamping component prepared by the method described in the fourth aspect of the present disclosure.

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

[0064] In a specific implementation manner, the coating thickness of the hot stamping formed component is 10-25 μm, which can have good anti-oxidation and anti-corrosion effects.

[0065] A sixth aspect of the present disclosure provides an automobile structural part, comprising the hot stamping formed component according to the fifth aspect of the present disclosure.

[0066] In a specific embodiment, the automobile structural parts include but are not limited to 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, center channels, roof reinforcement beams and other safety structural parts; they can also be used in the production of battery packs for new energy vehicles.

[0067] The present disclosure is further described in detail by way of examples. The raw materials used in the examples can all be obtained through commercial sources.

[0068] The martensitic structure photos of hot stamping steel plates were obtained by testing with a German ZEISS-LAB A1.MAT microscope.

[0069] Example 1

[0070] (1) After the steel plate substrate (the composition of the steel plate substrate is listed in Table 1) is pre-degreased, electrolytically degreased, brushed, rinsed, and dried 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 the cleaned steel plate substrate is placed in a vertical continuous annealing furnace, preheated, heated to the required strip annealing temperature of 800°C, with a dew point of -22°C, and soaked for 30 seconds, so that the pre-plated steel plate has an initial low-carbon area, thereby obtaining a first product;

[0071] (2) the first product is slowly cooled or rapidly cooled to 670° C. and then placed into a plating solution, the plating solution temperature is 680° C., and the hot dip plating time is 10 s; the plating solution comprises 10.4 wt % Si, 2.6 wt % Fe, less than 0.10 wt % impurities, and the balance is Al;

[0072] (3) Cooling: 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, remove excess plating solution on the at least one surface by air knife blowing to control the thickness of the coating on the at least one surface; the thickness of the coating is controlled within a range of 6 to 16 μm;

[0073] (4) Oiling: After coming out of the loop, the strip is smoothed and stretched, and then the passivation liquid is applied by the roller coater. The strip coated with the passivation liquid needs to be dried by hot air. Then the strip enters the horizontal inspection table and the vertical inspection table for surface quality inspection, and then enters the oiling machine for oiling. After being cut and sampled by the flying shear, it enters the coiler. Then it is packaged and put into storage (pre-plated steel plate);

[0074] (5) Hot stamping treatment: The pre-plated steel sheet was subjected to hot stamping treatment under the following conditions: heating temperature of 920°C, heating time of 230s, hot forming temperature of 700°C, holding time of 9s, cooling rate after hot stamping of 50°C / s, and die ejection temperature of 180°C. A hot stamping component was obtained. The thickness of the coating was in the range of 10-25μm.

[0075] The microscopic picture of the martensite structure of the hot stamping steel plate prepared in this embodiment is as follows: Figure 1 As shown by Figure 1 It can be seen that the martensite in the hot stamping steel plate prepared by using the steel plate matrix provided by the present disclosure is a dislocation martensite structure.

[0076] Embodiments 2 to 9

[0077] 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 as shown in Table 1; the rest of the process is the same as Example 1.

[0078] Comparative Examples 1 to 5

[0079] 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 as shown in Table 1; the rest of the process is the same as Example 1.

[0080] Table 1

[0081]

[0082] In Table 1, the unit of each metal component data is "weight %"; and the balance of the steel plate matrix in each embodiment and comparative example is Fe; the component content "-" indicates that the component is not added; the unit of Ms is "°C".

[0083] Test Case

[0084] The obtained untempered hot stamping flat die parts were tested for tensile strength, elongation and maximum bending angle according to the GBT228.1 room temperature tensile standard and the VDA-238 three-point bending standard. The VDA angle is obtained according to the calculation method of Appendix D in VDA 238-100:2020. And the data of the hot stamping steel sheets obtained in each embodiment and comparative example are the average values ​​of the three groups of test results to reduce the measurement error. The test results are listed in Table 2 below.

[0085] Table 2

[0086]

[0087] According to the data in Table 2, we can see that:

[0088] The steel plate substrates used in Comparative Examples 1 to 4 do not contain Mg and Cu, and the Si and Mn contents of the steel plate substrates in Examples 1, 3 to 4 are not within the range provided in the present disclosure, and their Ms temperatures are not within the range provided in the present disclosure. The C, Si and Mn contents of the steel plate substrate in Example 2 are not within the range provided in the present disclosure, and the component contents of the steel plate substrate used in Comparative Example 5 are not within the range provided in the present disclosure. The hot stamped steel plates prepared in Examples 1 to 2 and 4 to 5 have relatively high elongation and VDA angle, but their yield strength and tensile strength are relatively low, for example, the tensile strength cannot reach 2000 MPa. The strength performance, elongation and VDA angle of the hot stamped steel plate prepared in Comparative Example 3 are relatively low, which shows that the hot stamped steel plates prepared with the steel plate substrates provided in Comparative Examples 1 to 5 cannot achieve high strength and comprehensive performance of both plasticity and toughness. Compared with Comparative Examples 1 to 5, the hot stamped steel plates prepared with the steel plate substrates provided in the present disclosure in Examples 1 to 9 can have higher strength performance (yield strength ≥ 1250 MPa, tensile strength ≥2000MPa) and good toughness and plasticity (elongation ≥5%, VDA ≥40°);

[0089] Comparing Example 1 with Example 2, it can be seen that the Ms temperature of the steel plate substrate provided in Example 1 is within the preferred range provided in the present disclosure (Ms temperature ≥ 345°C), and the hot stamped steel plate prepared in Example 1 can have higher strength performance, and the elongation and VDA angle are also higher;

[0090] Comparing Examples 3 to 8 with Example 9, it can be seen that the contents of C, Si, Mn, Cr, Mg and Cu in the steel plate matrix used in Example 9 are not within the preferred range provided in the present disclosure, and the contents of one component of C, Si, Mn, Cr, Mg and Cu in the steel plate matrix used in Examples 3 to 8 are respectively not within the preferred range of the present disclosure. Compared with the hot stamped steel plate obtained in Example 9, the hot stamped steel plates obtained in Examples 3 to 8 can have higher strength performance, and the elongation and VDA angle are also higher;

[0091] Further comparing Examples 3 to 8 with Example 1, it can be seen that the component content of the steel plate matrix used in Example 1 is within the preferred range provided in the present disclosure, and the hot stamped steel plate produced in Example 1 can have higher strength performance, and the elongation and VDA angle are also higher.

[0092] The stress-strain curves of the hot stamping steel sheets prepared in Examples 1-2 and Example 9 are as follows: Figure 2 As shown by Figure 2 It can be seen that the hot stamped steel plate prepared from the steel plate matrix in Example 1 has higher strength while maintaining good elongation;

[0093] The load displacement curves of the hot stamping steel plates prepared in Examples 1-2 and Example 9 are as follows: Figure 3 As shown by Figure 3 It can be seen that the hot stamped steel plate prepared from the steel plate matrix in Example 1 has a better bending angle, that is, has better toughness.

[0094] The preferred embodiments of the present disclosure are 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 technical concept of the present disclosure, a variety of simple modifications can be made to the technical solution of the present disclosure, and these simple modifications all fall within the protection scope of the present disclosure.

[0095] It should also be noted that the various specific technical features described in the above specific embodiments can be combined in any suitable manner without contradiction. In order to avoid unnecessary repetition, the present disclosure will not further describe various possible combinations.

[0096] In addition, various embodiments of the present disclosure may be arbitrarily combined, and as long as they do not violate the concept of the present disclosure, they should also be regarded as the contents disclosed by the present disclosure.

Claims

1. A steel plate substrate, characterized in that: The steel plate matrix comprises 0.32-0.38 wt % of C, 0.70-0.90 wt % of Si, 0.30-0.50 wt % of Mn, 0.10 wt % or less of P, 0.10 wt % or less of S, 0.01-0.20 wt % of Cr, 0.001-0.01 wt % of B, 0.10-0.40 wt % of Al, 0.002-0.003 wt % of Mg, 0.22-0.30 wt % of Cu, 0.05-0.20 wt % of V, 0.10 wt % or less of impurities and the balance of Fe; The steel plate matrix is ​​a dislocation martensite matrix; The Ms of the steel plate substrate is calculated according to the following formula (1) ≥ 335: Ms=500-320×[C]-50×[Mn]-30×[Cr]-5×([Cu]+[Si]), formula (1); In formula (1), [C] represents the C content in the steel plate matrix, in weight %; [Mn] represents the Mn content in the steel plate matrix, in weight %; [Cr] represents the Cr content in the steel plate matrix, in weight %; [Cu] represents the Cu content in the steel plate matrix, in weight %; and [Si] represents the Si content in the steel plate matrix, in weight %.

2. The steel plate substrate according to claim 1, characterized in that: The total content of Si and Cr in the steel plate matrix is ​​greater than 1 wt %.

3. The steel plate substrate according to claim 1, characterized in that: The steel plate substrate has a Ms≥345.

4. A method for preparing a pre-plated steel sheet, characterized in that: The following steps are involved: S1. Annealing the steel plate substrate as claimed in any one of claims 1 to 3 to obtain a first product; S2, cooling the first product and then placing it into a plating solution for hot dip plating.

5. The method according to claim 4, characterized in that In step S1, the annealing treatment conditions include: annealing temperature of 780-830°C, dew point of -30 to -20°C, and soaking time of 25-35s.

6. The method according to claim 4, characterized in that In step S2, the plating solution includes 9-12 wt% Si, 2-3 wt% Fe, less than 0.10 wt% impurities and the balance 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 seconds; The thickness of the coating obtained by the hot-dip plating process is 6-16 μm.

7. The pre-plated steel sheet prepared according to the method according to any one of claims 4 to 6.

8. A method for preparing a hot stamping formed component, characterized in that: The following steps are involved: The pre-plated steel sheet according to claim 7 is subjected to hot stamping treatment.

9. The method according to claim 8, characterized in that The conditions of the hot stamping treatment include: a heating temperature of 880-940°C, a heating time of 180-240s, a hot forming temperature of 680-720°C, a holding time of 8-10s, a cooling rate after hot stamping of 40-60°C / s, and a demolding temperature below 200°C.

10. A hot stamping component produced according to the method of claim 8 or 9.

11. The hot stamping component according to claim 10, characterized in that: The yield strength of the hot stamping formed component is ≥1250MPa, the tensile strength is ≥2000MPa, the elongation is ≥5%, and the VDA is ≥40°.

12. An automobile structural part, characterized in that: The hot stamping formed component comprises the hot stamping formed component according to claim 10 or 11.

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