Steel plate base body, pre-plated steel plate and preparation method thereof, hot 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 forming component and a preparation method thereof, and an automobile structural part. The steel plate substrate comprises 0.35 to 0.45 wt% of C, 0.1 to 0.5 wt% of Si, 0.6 to 1.6 wt% of Mn, 0.10 wt% or less of P, 0.10 wt% or less of S, 0.1 to 0.5 wt% of Cr, 0.001 to 0.006 wt% of B, 0.10 to 0.50 wt% of Al, 0.001 to 0.1 wt% of Ti, 0.001 to 0.1 wt% of Nb, 0.0002 to 0.02 wt% of RE, 0.2 wt% or less of impurities, and the balance of Fe; wherein RE comprises one or more of Ce, La, Y, Pr, Nd and Sm. The strength performance of the hot-formed steel plate can be improved, and the hydrogen-induced delayed cracking condition can be improved.

Description

Technical Field

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

[0002] New energy vehicles have increasingly higher requirements in areas such as emissions, endurance, and passive safety, especially in the area of collision safety. More and more OEMs are paying attention to working conditions such as drilling, top pressure, and hillside rollover, and have put forward higher requirements for ultra-high-strength hot-formed steel. The highest-strength hot-formed material used by mainstream OEMs has a tensile strength of approximately 2000MPa. With the emergence of extreme testing conditions, there is a demand for higher-strength hot-formed materials. However, as the strength of the material increases, the toughness will decrease significantly, and the tendency of hydrogen-induced delayed cracking will become more and more obvious, causing the material to crack when it is slightly deformed, or hydrogen-induced delayed cracking will occur during the storage, transportation, and welding stages after the parts are produced, affecting the use of the parts. 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-formed component and a preparation method thereof, and an automobile structural component, which can improve the strength performance of the hot-formed steel plate and improve the hydrogen-induced delayed cracking.

[0004] In order to solve the above technical problems, 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 0.35~0.45 weight% of C, 0.1~0.5 weight% of Si, 0.6~1.6 weight% of Mn, less than 0.10 weight% of P, less than 0.10 weight% of S, 0.1~0.5 weight% of Cr, 0.001~0.006 weight% of B, 0.10~0.50 weight% of Al, 0.001~0.1 weight% of Ti, 0.001~0.1 weight% of Nb, 0.0002~0.02 weight% of RE, less than 0.2 weight% of impurities and the balance Fe; wherein RE includes one or more of Ce, La, Y, Pr, Nd and Sm.

[0005] In one embodiment, the steel plate matrix includes 0.35-0.42 wt% C, 0.1-0.4 wt% Si, 0.8-1.2 wt% Mn, 0.10 wt% or less P, 0.10 wt% or less S, 0.2-0.4 wt% Cr, 0.001-0.006 wt% B, 0.10-0.50 wt% Al, 0.001-0.08 wt% Ti, 0.001-0.08 wt% Nb, 0.0025-0.01 wt% RE, 0.2 wt% or less impurities, and the balance Fe. The steel plate matrix having the preferred component contents provided in this embodiment is more conducive to obtaining hot-formed components with high strength, high toughness, and high resistance to hydrogen embrittlement delayed cracking.

[0006] In one embodiment, the content ratio of RE:S in the steel plate matrix is 1-5, which can take into account both toughness and production continuity.

[0007] In one embodiment, the total content of Ti and Nb in the steel plate matrix is 0.01~0.2% by weight; when the total content of Ti and Nb in the steel plate matrix is within the range of this embodiment, Nb and Ti can exert a better dispersion strengthening and grain refinement effect in the steel plate matrix, which is beneficial to improving the performance of the hot stamping steel plate.

[0008] In one embodiment, the ratio of C / (Ti+Nb) in the steel plate matrix is 3-15, which is more conducive to the formation of carbides by Nb and Ti with the C element, thereby improving the performance of the steel plate matrix.

[0009] A second aspect of the present disclosure provides a method for preparing a pre-plated 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. Cooling the first product and placing it into a plating solution for hot-dip plating.

[0010] In one embodiment, in step S1, the annealing treatment conditions include: annealing temperature of 780-830°C, dew point of -20 to -3°C, and soaking time of 25-35s, which is conducive to obtaining hot stamping steel plates with higher strength and toughness.

[0011] In one embodiment, 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; 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, which is conducive to improving the coating quality; The coating obtained by the hot-dip plating process has a thickness of 6 to 16 μm and has good anti-oxidation and anti-corrosion effects.

[0012] A third aspect of the present disclosure provides a pre-plated steel plate prepared according to the method described in the second aspect of the present disclosure.

[0013] A fourth aspect of the present disclosure provides a method for preparing a thermoformed component, comprising the following steps: The pre-plated steel sheet described in the third aspect of the present disclosure is subjected to hot forming treatment.

[0014] In one embodiment, the conditions of the hot forming treatment include: a heating temperature of 880~920°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, which is beneficial to improving the performance of the hot stamped steel plate.

[0015] A fifth aspect of the present disclosure provides a hot-formed component prepared by the method described in the fourth aspect of the present disclosure.

[0016] In one embodiment, the yield strength of the thermoformed component is ≥1350 MPa, the tensile strength is ≥2000 MPa, the elongation is ≥4.5%, and the ultimate cold bending angle is ≥40°, and the component has excellent comprehensive performance.

[0017] A sixth aspect of the present disclosure provides an automobile structural component, comprising the thermoformed component described in the fifth aspect of the present disclosure.

[0018] Through the above technical solution, the present disclosure provides a steel plate substrate, a pre-plated steel plate and a preparation method thereof, a hot-formed component and a preparation method thereof, and an automotive structural part. By controlling the C element content in the steel plate substrate and the addition and content control of trace elements and rare earths, especially controlling the addition and content control of Ti, Nb, and RE (rare earth metals), and then subjecting the steel plate substrate to a coating treatment and hot-forming treatment, a hot-formed steel plate with high strength and high toughness can be obtained, and hydrogen-induced delayed cracking is effectively improved, which has a good application effect in automotive structural parts.

[0019] Other features and advantages of the present disclosure will be described in detail in the following detailed description. BRIEF DESCRIPTION OF THE DRAWINGS

[0020] 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 detailed description, they are used to explain the present disclosure but do not constitute a limitation of the present disclosure. In the accompanying drawings: Figure 1 (a) is a photograph of MnS grains before refinement (Comparative Example 1); Figure 1 (b) is a photograph of the refined MnS grains (Example 1); Figure 2 Middle (c) is a photograph of Al2O3 grains before refinement (Comparative Example 1); Figure 2 (d) is a photograph of the refined Al2O3 grains (Example 1). DETAILED DESCRIPTION

[0021] The following describes the specific embodiments of the present disclosure in detail 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 intended to limit the present disclosure.

[0022] A first aspect of the present disclosure provides a steel plate substrate, which, based on the total weight of the steel plate substrate, comprises 0.35-0.45 wt% of C (carbon), 0.1-0.5 wt% of Si (silicon), 0.6-1.6 wt% of Mn (manganese), less than 0.10 wt% of P (phosphorus), less than 0.10 wt% of S (sulfur), 0.1-0.5 wt% of Cr (chromium), 0.001-0.006 wt% of B (boron), 0.10-0.50 wt% of Al (aluminum), 0.001-0.1 wt% of Ti (titanium), 0.001-0.1 wt% of Nb (niobium), 0.0002-0.02 wt% of RE (rare earth elements), less than 0.2 wt% of impurities, and the balance of Fe (iron); wherein RE comprises one or more of Ce, La, Y, Pr, Nd, and Sm.

[0023] The present disclosure provides a steel plate substrate. By controlling the C element content in the steel plate substrate and the addition and content control of trace elements and rare earths, especially controlling the addition and content control of Ti, Nb, and RE (rare earth metals), and then subjecting the steel plate substrate to coating and hot forming treatments, a hot-formed steel plate with high strength and high toughness can be obtained, and hydrogen-induced delayed cracking is effectively improved, with good application effects in automotive structural parts.

[0024] According to the present disclosure, C can significantly improve the strength and hardenability of steel plate materials, but while the C element improves the strength of the material, it also reduces the toughness of the material. The present disclosure controls the C content within the range of 0.35~0.45% by weight, and the resulting steel plate material can take into account both strength and toughness.

[0025] According to the present disclosure, the addition of element C can lead to a decrease in toughness. The addition of Nb and Ti in the present disclosure can form carbides with element C, improving the toughness of the material through grain refinement and precipitation strengthening. Simultaneously, the formation of carbides further reduces the carbon content of the matrix, further improving the toughness of the material. The present disclosure adds 0.001-0.1 wt% Ti and 0.001-0.1 wt% Nb to the steel plate matrix, effectively improving the toughness of the hot-formed steel sheet produced from the steel plate matrix.

[0026] According to the present disclosure, adding a trace amount (0.0002-0.02 wt%) of rare earth elements (RE) can purify molten steel and reduce the O and S contents in the molten steel. At the same time, the addition of rare earth elements can convert strip-shaped and angular MnS and Al2O3 inclusions in the steel into spherical rare earth compounds. Such rare earth compounds have a lower hardness, and when the material is deformed by force, the stress concentration between the inclusions and the matrix is reduced, thereby inhibiting the initiation and propagation of cracks. Rare earth elements can segregate at grain boundaries, refine austenite grains, and further improve the toughness of the material. In addition, rare earth elements form hydrogen traps in the steel, capturing hydrogen atoms and improving hydrogen-induced delayed cracking.

[0027] In the present disclosure, impurities in the steel plate matrix refer to trace impurities (such as As, Sb, etc.) that are inevitably introduced during the preparation of the steel plate matrix and are negligible in the overall composition of the steel plate matrix.

[0028] In a preferred embodiment, the steel plate substrate includes 0.35-0.42 wt% C, 0.1-0.4 wt% Si, 0.8-1.2 wt% Mn, 0.10 wt% or less P, 0.10 wt% or less S, 0.2-0.4 wt% Cr, 0.001-0.006 wt% B, 0.10-0.50 wt% Al, 0.001-0.08 wt% Ti, 0.001-0.08 wt% Nb, 0.0025-0.01 wt% RE, 0.2 wt% or less impurities, and the balance Fe. The steel plate substrate having the preferred component contents provided in this embodiment is more conducive to obtaining hot-formed components with high strength, high toughness, and high resistance to hydrogen embrittlement and delayed cracking.

[0029] In one embodiment, the RE:S ratio in the steel plate matrix is 1 to 5. While adding a small amount of rare earth elements can significantly improve toughness, rare earth elements are susceptible to oxidation. If added in excessive amounts, rare earth oxides can easily clog the casting nozzle, impacting production efficiency. The present disclosure controls the RE:S ratio in the steel plate matrix within a range of 1 to 5, achieving a balance between toughness and production continuity.

[0030] In a preferred embodiment, the ratio of RE to S in the steel plate matrix is 2 to 4, more preferably 2.5 to 3.5. When the ratio of RE to S in the steel plate matrix is within the preferred range of this embodiment, a steel plate with improved toughness and production continuity can be obtained.

[0031] In one embodiment, the total content of Ti and Nb in the steel plate matrix is 0.01 to 0.2% by weight, preferably 0.03 to 0.1% by weight. The inventors of the present disclosure have discovered that when the total content of Ti and Nb in the steel plate matrix is within the range of this embodiment, especially within the preferred range, Nb and Ti can achieve a more effective dispersion strengthening and grain refinement effect in the steel plate matrix, thereby improving the performance of the hot stamped steel plate.

[0032] In one embodiment, the ratio of C / (Ti+Nb) in the steel plate matrix is 3 to 15; adding C, Ti, and Nb to the steel plate matrix according to the ratio of C content to the total content of Ti+Nb provided in the present disclosure is more conducive to the formation of carbides between Nb and Ti and the C element, thereby improving the performance of the steel plate matrix.

[0033] In a specific embodiment, the steel plate substrate can be prepared by conventional processes in the art.

[0034] A second aspect of the present disclosure provides a method for preparing a pre-plated 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. Cooling the first product and placing it into a plating solution for hot-dip plating.

[0035] 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 anti-oxidation and anti-corrosion effects.

[0036] In one embodiment, in step S1, before performing the annealing treatment, the process further includes: 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; the annealing treatment can be carried out in a vertical continuous annealing furnace.

[0037] In one embodiment, in step S1, the annealing conditions include: an annealing temperature of 780 to 830°C, a dew point of -20 to -3°C, and a soaking time of 25 to 35 seconds; preferably, the annealing temperature is 790 to 820°C, the dew point is -22 to -5°C, and the soaking time is 28 to 32 seconds. Annealing according to the process conditions in this embodiment, especially according to the preferred process conditions, is conducive to obtaining a hot stamped steel plate with higher strength and toughness.

[0038] In one embodiment, in step S2, the plating solution includes 9-12 weight % of Si, 2-3 weight % of Fe, 0.10 weight % or less of impurities, and the remainder is Al; preferably, the plating solution includes 10-11 weight % of Si, 2.5-3.0 weight % of Fe, 0.10 weight % or less of impurities, and the remainder is A; the plating solution provided by this embodiment has better corrosion resistance.

[0039] In one embodiment, the conditions for the hot dip plating treatment include: the temperature of the first product after cooling is 600~680℃, the temperature of the plating solution is 650~700℃, and the hot dip plating time is 2~15s; preferably, the temperature of the first product after cooling is 620~670℃, the temperature of the plating solution is 660~690℃, 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 the hot dip plating treatment according to the preferred process conditions, are beneficial to improving the coating quality.

[0040] In a specific implementation manner, after step S3, the method further includes: 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 a conventional process in the art; S4. After coming out of the loop, the strip (steel plate substrate) is subjected to skin finishing and stretching straightening, and then coated with passivation liquid by a roller coater. The strip coated with passivation liquid needs to be dried with 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 is cut and sampled by the flying shear before entering the coiler; and is packed and put into storage.

[0041] In a specific embodiment, the coating obtained by the hot-dip plating process has a thickness of 6 to 16 μm, and can have good anti-oxidation and anti-corrosion effects.

[0042] A third aspect of the present disclosure provides a pre-plated steel plate prepared according to the method described in the second aspect of the present disclosure.

[0043] A fourth aspect of the present disclosure provides a method for preparing a thermoformed component, comprising the following steps: The pre-plated steel sheet described in the third aspect of the present disclosure is subjected to hot forming treatment.

[0044] In a preferred embodiment, the hot forming process conditions include: a heating temperature of 880-920°C, preferably 900-910°C, a heating time of 180-240 seconds, a hot forming temperature of 680-720°C, a holding time of 8-10 seconds, a cooling rate after hot stamping of 40-60°C / s, and a die ejection temperature below 200°C. Performing hot forming according to the process conditions provided in this embodiment is beneficial for improving the performance of hot stamped steel sheets.

[0045] A fifth aspect of the present disclosure provides a hot-formed component prepared by the method described in the fourth aspect of the present disclosure.

[0046] In a specific embodiment, the yield strength of the thermoformed component is ≥1350 MPa, the tensile strength is ≥2000 MPa, the elongation is ≥4.5%, and the ultimate cold bending angle is ≥40°; preferably, the yield strength is ≥1450 MPa, the tensile strength is ≥2100 MPa, the elongation is ≥5%, and the ultimate cold bending angle is ≥45°.

[0047] In a specific embodiment, the coating thickness of the thermoformed component is 10-25 μm, which can have good anti-oxidation and anti-corrosion effects.

[0048] A sixth aspect of the present disclosure provides an automobile structural component, comprising the thermoformed component described in the fifth aspect of the present disclosure.

[0049] 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.

[0050] The present disclosure is further described in detail below through examples. The raw materials used in the examples can be obtained through commercial channels.

[0051] Example 1 (1) The steel plate substrate (the composition of the steel plate substrate is listed in Table 1) is subjected to pre-degreasing, electrolytic degreasing, brushing, rinsing, and drying in a cleaning section, so that 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 in the range of -20 to -3°C, and soaked for 30 seconds, so that the pre-plated steel plate has an initial low carbon area, thereby obtaining a first product; (2) the first product is slowly cooled or rapidly cooled to 640° C. and then placed in a plating solution having a plating temperature of 680° C. and a hot dip plating time of 9 seconds; the plating solution comprises 11 wt % Si, 2.5 wt % Fe, less than 0.2 wt % of unavoidable impurities, and the balance being Al; (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 to be within the range of 6 to 16 μm; (4) Oiling: After coming out of the looper, the strip is subjected to skin-finishing and stretching straightening, and then the strip is coated with passivation liquid by a roller coater. The strip coated with passivation liquid needs to be dried with hot air. The strip then enters the horizontal inspection table and the vertical inspection table for surface quality inspection, and then enters the oiling machine for oiling. It is cut and sampled by the flying shear and then enters the coiler. It is then packaged and put into storage (pre-coated steel plate); (5) Hot forming treatment: The pre-plated steel sheet was subjected to hot forming treatment. The hot forming treatment conditions included: heating temperature of 860°C, heating time of 210s, hot forming temperature of 210°C, holding time of 8s, cooling rate after hot stamping of 50°C / s, and die ejection temperature of ≤200°C. The hot formed component was obtained. The thickness of the coating was in the range of 6-16μm.

[0052] Examples 2 to 12 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.

[0053] Comparative Examples 1 to 7 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.

[0054] Comparative Example 8 Referring to the preparation method in Example 1, the difference from Example 1 is that the component content of the steel plate matrix used includes: 0.307 weight% C, 0.26 weight% Si, 1.02 weight% Mn, 0.15 weight% Cr, 0.19 weight% Al, 0.021 weight% Nb, 0.0022 weight% B, 0.0024 weight% N, 0.17 weight% V, less than 0.013 weight% P, 0.009 weight% S, 0.1 weight% Cu, 0.1 weight% Co, 0.002 weight% REM, and the balance Fe; the rest of the process is the same as in Example 1.

[0055] Comparative Example 9 Referring to the preparation method in Example 1, the difference from Example 1 is that the components of the steel plate matrix used include: 0.2 weight% C, 1.35 weight% Mn, 1.5 weight% Si, 2.5 weight% Cr, 0.25 weight% Y, 0.02 weight% Nb, 0.03 weight% Al, 0.01 weight% V, 0.03 weight% Ti, and 0.05 weight% Cu; the rest of the process is the same as in Example 1.

[0056] Table 1

[0057] In Table 1, the unit of each metal component data is "weight %"; 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.

[0058] Test Example 1 The untempered hot stamping flat die parts obtained in the above examples and comparative examples were tested for yield strength, tensile strength, elongation, maximum bend angle, and delayed cracking according to the GBT 228.1 room temperature tensile test and the VDA 238 three-point bend test. The VDA angle was calculated according to Appendix D of VDA 238-100: 2020. The delayed cracking test was performed using a stress of 1.0 times the yield strength and the test results were obtained after 120 hours of stagnation. The final test results were averaged from three sets of test results to minimize error. The test results are listed in Table 2 below.

[0059] Table 2

[0060] According to the data in Table 2, we can see that: In Comparative Examples 1 to 3, Ti, Nb, and RE were not added to the steel plate matrix. The yield strength and tensile strength of the hot stamped components obtained in Comparative Examples 1 to 3 were both low, and the required strength properties could not be achieved. The RE content in Comparative Example 4 is too high, and the yield strength and tensile strength of the hot stamped component obtained in Comparative Example 4 are both low, and the elongation and ultimate cold bending angle are also low, and cracking occurs in the delayed cracking performance test. Comparing Comparative Example 4 with Example 10 shows that the RE content of the steel plate substrate in Example 10 is within the optimized range provided by the present disclosure, and the yield strength, tensile strength, elongation, and ultimate cold bending angle of the hot stamped component obtained in Example 10 are higher. The Ti and Nb contents of the steel plate matrix in Comparative Example 5 are too high. Comparing Comparative Example 5 with Example 10, it can be seen that the Ti and Nb contents of the steel plate matrix in Example 10 are within the optimized range provided by the present disclosure. The yield strength and tensile strength of the hot stamped component obtained in Example 10 are higher. In addition, the excessively high Ti and Nb contents in Comparative Example 5 do not significantly improve the elongation and the ultimate cold bending angle, but will significantly increase the cost, which is not conducive to industrial mass production. The C content in the steel plate matrix in Comparative Example 6 is too low, and the Si, Mn, and Cr contents in the steel plate matrix in Comparative Example 7 are not within the ranges provided in the present disclosure. The yield strength and tensile strength of the hot stamping components obtained in Comparative Examples 6 and 7 are both low, and the overall performance is poor; The composition of the steel plate matrix in Comparative Examples 8 and 9 is not within the scope of the present disclosure. The yield strength and tensile strength of the hot stamping components obtained in Comparative Examples 8 and 9 are both low, and the overall performance is poor. The hot stamped components obtained by using the steel plate substrate provided by the present disclosure in Examples 1 to 12 have high yield strength and tensile strength (yield strength ≥ 1350 MPa, tensile strength ≥ 2000 MPa), and can also have good elongation and ultimate cold bending angle, with better overall performance; Comparing Example 11 with Example 12, it can be seen that the weight ratio of RE / S of the steel plate substrate in Example 11 is within the optimized range provided by the present disclosure. The hot stamped component obtained in Example 11 has higher yield strength and tensile strength, and also better elongation and ultimate cold bending angle, and better overall performance. Comparing Example 1 with Example 11, it can be seen that the weight ratio of RE / S of the steel plate substrate in Example 1 is within the further preferred range provided by the present disclosure, and the hot stamping formed component obtained in Example 1 has better comprehensive performance; Comparing Example 9 with Example 10, it can be seen that the composition of the steel plate matrix in Example 9 is within the preferred range provided in the present disclosure, and the total content of Ti+Nb is also within the preferred range provided in the present disclosure. The hot stamping formed component obtained in Example 9 has better comprehensive performance; Comparing Example 1 with Example 9, it can be seen that the composition of the steel plate matrix and the total content of Ti+Nb in Example 1 are within the preferred ranges provided in the present disclosure, and the RE / S ratio is also within the range provided in the present disclosure. The hot stamping formed component obtained in Example 1 has better comprehensive performance; Comparing Example 1 with Examples 7-8, it can be seen that the Ti and Nb contents and the total Ti+Nb content in the steel plate matrix of Example 1 are within the preferred ranges disclosed herein, and the hot stamping formed component obtained in Example 1 has better comprehensive performance; Comparing Example 1 with Examples 2 to 6, it can be seen that the composition of the steel plate substrate in Example 1 is within the preferred range provided in the present disclosure, and the hot stamping formed component obtained in Example 1 has better comprehensive performance.

[0061] Test Example 2 This test example is used to illustrate the effect of rare earth metal elements on grain refinement in the steel plate matrix.

[0062] The photos before and after grain refinement were obtained using an AXIO-Vert A1 metallographic microscope.

[0063] Figure 1 (a) and (b) show the MnS grains before refinement (the steel plate matrix without rare earth metal addition in Comparative Example 1) and the MnS grains after refinement (the steel plate matrix with rare earth metal addition in Example 1), respectively. Figure 1 It can be seen that the originally long strip-shaped sulfide inclusions such as MnS in the steel will be transformed into small, dispersed spherical rare earth complex sulfide inclusions under the action of rare earths; the spherical inclusions reduce stress concentration and improve the strength and toughness of the steel.

[0064] Figure 2 (c) and (d) in FIG1 respectively show the Al2O3 grains before refinement (the steel plate matrix without rare earth metal addition in Comparative Example 1) and the Al2O3 grains after refinement (the steel plate matrix with rare earth metal addition in Example 1). Figure 2 It can be seen that the sharp Al2O3 inclusions are transformed into spherical inclusions under the action of rare earths, which reduces stress concentration and improves the strength and toughness of steel.

[0065] 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 of the above embodiments. Within 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 scope of protection of the present disclosure.

[0066] It should also be noted that the various specific technical features described in the above specific embodiments can be combined in any appropriate manner without contradiction. In order to avoid unnecessary repetition, the present disclosure will not further describe various possible combinations.

[0067] In addition, the 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: Based on the total weight of the steel plate substrate, the steel plate substrate includes 0.35-0.45 weight% of C, 0.1-0.5 weight% of Si, 0.6-1.6 weight% of Mn, less than 0.10 weight% of P, less than 0.10 weight% of S, 0.1-0.5 weight% of Cr, 0.001-0.006 weight% of B, 0.10-0.50 weight% of Al, 0.001-0.1 weight% of Ti, 0.001-0.1 weight% of Nb, 0.0002-0.02 weight% of RE, less than 0.2 weight% of impurities and the balance Fe; wherein RE includes one or more of Ce, La, Y, Pr, Nd and Sm.

2. The steel plate substrate according to claim 1, characterized in that: The steel plate matrix includes 0.35-0.42 wt% of C, 0.1-0.4 wt% of Si, 0.8-1.2 wt% of Mn, 0.10 wt% or less of P, 0.10 wt% or less of S, 0.2-0.4 wt% of Cr, 0.001-0.006 wt% of B, 0.10-0.50 wt% of Al, 0.001-0.08 wt% of Ti, 0.001-0.08 wt% of Nb, 0.0025-0.01 wt% of RE, 0.2 wt% or less of impurities, and the balance of Fe.

3. The steel plate substrate according to claim 1, wherein: The content ratio of RE:S in the steel plate matrix is 1-5.

4. The steel plate substrate according to claim 1, wherein: In the steel plate matrix, the total content of Ti and Nb is 0.01-0.2% by weight; Optionally, in the steel plate matrix, the content ratio of C / (Ti+Nb) is 3-15.

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

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

7. The method according to claim 5, 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.

8. The pre-plated steel sheet prepared according to the method according to any one of claims 5 to 7.

9. A method for preparing a hot-formed component, characterized in that: The following steps are involved: The pre-plated steel sheet according to claim 9 is subjected to hot forming treatment.

10. The method according to claim 9, characterized in that The conditions of the hot forming treatment include: heating temperature of 880~920℃, 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 mold ejection temperature below 200℃.

11. A hot-formed component produced according to the method of claim 9 or 10.

12. The thermoformed component according to claim 11, characterized in that The yield strength of the thermoformed component is ≥1350 MPa, the tensile strength is ≥2000 MPa, the elongation is ≥4.5%, and the ultimate cold bending angle is ≥40°.

13. An automobile structural part, characterized in that: The thermoformed component comprises the thermoformed component according to claim 11 or 12.

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