Tailored blanks, tailored blank hot formed parts, methods of making the same, and vehicles

Abstract

The application provides a tailor-welded blank, a tailor-welded blank hot-formed part, a preparation method thereof and a vehicle, wherein the tailor-welded blank comprises a first plated steel sheet and a second plated steel sheet, the thickness and / or strength of the first plated steel sheet is different from that of the second plated steel sheet, the first plated steel sheet comprises a first plating layer, the second plated steel sheet comprises a second plating layer, the thickness of the first plating layer is different from that of the second plating layer, and the first plated steel sheet and the second plated steel sheet are connected by laser tailor-welding. It is verified by experiments that, by adjusting the thickness of the plating layer of different plated steel sheets, different plated steel sheets can reach full austenitization at a substantially same time, so that, under the premise that different plated steel sheets all reach full austenitization, over-heating of a plated steel sheet with a thinner thickness or weaker strength for a long time is avoided, and the problem of incomplete austenite transformation or over-heating of different plated steel sheets caused by the same heating time is fundamentally solved.

Description

Technical Field

[0001] This application relates to the field of thermoforming technology, and in particular to a welded plate, a welded plate thermoformed component, a method for preparing the same, and a vehicle. Background Technology

[0002] Many hot-formed parts of automobile bodies (such as door rings) are made by laser welding together aluminum-silicon coated steel sheets of different thicknesses or strengths (usually referring to the strength after hot stamping), followed by sequential heating and hot stamping. During the heating process, coated steel sheets of different thicknesses or strengths need to be heated at the same temperature for the same amount of time, ensuring that all coated steel sheets of different strengths or thicknesses are heated uniformly and fully austenitized.

[0003] Because coated steel sheets of different thicknesses or strengths heat at different rates, thinner or weaker coated steel sheets heat up faster and require less time to reach full austenitization, while thicker or stronger coated steel sheets heat up slower and require more time to reach full austenitization. If coated steel sheets of different thicknesses or strengths are heated simultaneously for a prolonged period, the thinner or weaker coated steel sheets will overheat for an extended period, leading to a decrease in toughness and weldability. Conversely, if coated steel sheets of different thicknesses or strengths are heated simultaneously for a shorter period, the thicker or stronger coated steel sheets will be underheated, failing to achieve full austenitization, resulting in insufficient strength after hot stamping.

[0004] Therefore, how to achieve full austenitization of coated steel sheets of different thicknesses or strengths in a basically similar amount of time is an urgent problem to be solved. Summary of the Invention

[0005] In view of this, the purpose of this application is to provide a welded plate, a welded plate thermoformed component, a method for preparing the same, and a vehicle, so as to solve or partially solve the problems raised in the prior art.

[0006] To achieve the above objectives, the first aspect of this application provides a welded plate, comprising: a first coated steel plate and a second coated steel plate, wherein the thickness and / or the strength after hot stamping of the first coated steel plate are different from those of the second coated steel plate, the first coated steel plate includes a first coating, the second coated steel plate includes a second coating, the thickness of the first coating is different from that of the second coating, and the first coated steel plate and the second coated steel plate are connected by laser welding.

[0007] The first coated steel sheet includes a first coating and a first substrate located at the bottom of the first coating. For the first coated steel sheet, the factors affecting the heating time are the thickness of the first coated steel sheet (the thickness of the first coated steel sheet = the thickness of the first coating + the thickness of the first substrate) and the strength of the first coated steel sheet after hot stamping.

[0008] Similarly, the second coated steel sheet includes a second coating and a second substrate located at the bottom of the second coating. For the second coated steel sheet, the factors affecting the heating time are the thickness of the second coated steel sheet (the thickness of the second coated steel sheet = the thickness of the second coating + the thickness of the second substrate) and the strength of the second coated steel sheet after hot stamping.

[0009] Furthermore, the thickness of the first coated steel plate is greater than the thickness of the second coated steel plate, and the thickness of the first coating is less than the thickness of the second coating.

[0010] In this design, the thickness of the first coated steel plate is greater than that of the second coated steel plate. Therefore, the thickness of the first coating is less than that of the second coating. By reducing the thickness of the first coating on the thicker first coated steel plate, the heating time required for the first coated steel plate to achieve full austenitization is shortened. At the same time, by increasing the thickness of the second coating on the thinner second coated steel plate, the heating time required for the second coated steel plate to achieve full austenitization is extended. Ultimately, the heating times for the first and second coated steel plates to achieve full austenitization are basically the same, avoiding the problems of incomplete austenite transformation or overheating of different coated steel plates.

[0011] Furthermore, the thickness of the first coating is 4–15 μm, and the thickness of the second coating is 18–37 μm.

[0012] In the industry, coating thickness is mostly expressed in g / m² in the delivery condition. 2 For ease of understanding, the coating thickness is expressed in μm in this application. The thickness of the first coating is 4–15 μm (equivalent to 10–40 g / m²). 2 The thickness of the second coating is 18–37 μm (equivalent to 50–100 g / m²). 2 ).

[0013] Furthermore, the thickness of the first coating is 5–15 μm (equivalent to 15–40 g / m²). 2 The thickness of the second coating is 19–33 μm (equivalent to 70–90 g / m²). 2 ).

[0014] Furthermore, in response to determining that the thickness of the first coated steel plate is greater than 1.8 mm, the difference between the thickness of the first coated steel plate and the thickness of the second coated steel plate is 0 to 0.6 mm.

[0015] In response to determining that the thickness of the first coated steel sheet is between 1.1 and 1.8 mm, the difference between the thickness of the first coated steel sheet and the thickness of the second coated steel sheet is 0 to 0.4 mm.

[0016] When the thickness of the first coated steel plate is greater than 1.8 mm, the first coated steel plate is thicker (i.e. the first substrate is thicker), and the heating rate is slower. Therefore, it is permissible for the thickness of the first coated steel plate and the thickness of the second coated steel plate to differ more significantly in order to balance the heating time of the two.

[0017] When the thickness of the first coated steel plate is less than or equal to 1.8 mm, the first coated steel plate is relatively thin (i.e., the first substrate is relatively thin), and the heating rate is relatively fast. Therefore, the difference between the thickness of the first coated steel plate and the thickness of the second coated steel plate should not be too large. Otherwise, the second coated steel plate will be too thin, making it very easy to overheat, resulting in poor toughness and weldability.

[0018] However, in actual production processes, the thickness of the first and second coated steel plates must be ≥0.7mm to meet actual production requirements. Therefore, the minimum thickness of the second coated steel plate is 0.7mm, and correspondingly, the minimum thickness of the first coated steel plate is 1.1mm.

[0019] Furthermore, in response to determining that the thickness of the first coated steel sheet is greater than 1.8 mm and the strength of the second coated steel sheet after hot stamping is greater than or equal to 1000 MPa, the difference between the thickness of the first coated steel sheet and the thickness of the second coated steel sheet is 0 to 0.6 mm.

[0020] In response to determining that the thickness of the first coated steel sheet is greater than 1.8 mm and the strength of the second coated steel sheet after hot stamping is less than 1000 MPa, the difference between the thickness of the first coated steel sheet and the thickness of the second coated steel sheet is 0.2 to 0.6 mm.

[0021] Furthermore, in response to determining that the thickness of the first coated steel sheet is between 1.1 and 1.8 mm and the strength of the second coated steel sheet after hot stamping is greater than or equal to 1000 MPa, the difference between the thickness of the first coated steel sheet and the thickness of the second coated steel sheet is 0 to 0.4 mm.

[0022] In response to determining that the thickness of the first coated steel sheet is between 1.1 and 1.8 mm and the strength of the second coated steel sheet after hot stamping is less than 1000 MPa, the difference between the thickness of the first coated steel sheet and the thickness of the second coated steel sheet is 0.2 to 0.4 mm.

[0023] Since the first coated steel plate is relatively thick and is used as a crash barrier in practical applications, the strength of the first coated steel plate after hot stamping is also relatively large. Typically, the strength of the first coated steel plate used as a crash barrier after hot stamping is greater than or equal to 1300MPa.

[0024] The second-coated steel sheet is thinner and is used as an energy-absorbing zone in practical applications, thus allowing for a wider range of selectable strengths after hot stamping. However, when the strength of the second-coated steel sheet after hot stamping is greater than or equal to 1000 MPa and less than 1000 MPa, the heating rate differs significantly due to their different microstructures. Therefore, when the strength of the second-coated steel sheet after hot stamping is greater than or equal to 1000 MPa, the heating rate is slower, allowing for a larger difference in thickness between the second and first-coated steel sheets; conversely, when the strength of the second-coated steel sheet after hot stamping is less than 1000 MPa, the heating rate is faster, allowing for a smaller difference in thickness between the second and first-coated steel sheets to balance their heating times.

[0025] Furthermore, both the first coating and the second coating are silicon-aluminum coatings, and the aluminum content in the first coating and the second coating is greater than or equal to 85 wt%.

[0026] The first and second coatings contain a large amount of aluminum. Due to the extremely strong thermal conductivity of aluminum, the first and second coatings can significantly affect the heating time of the first and second coated steel plates.

[0027] Furthermore, the silicon content in the first coating and the second coating is 5 to 11 wt%, and the iron content is less than or equal to 4 wt%.

[0028] Furthermore, the strength, element content, and mechanical properties of both the first and second substrates after hot stamping all meet the following conditions (for ease of description, the first and second substrates will be referred to as substrates):

[0029] When the strength of the substrate after hot stamping is 1300-1650 MPa, the substrate comprises the following components: C 0.18-0.26 wt%, Si 0.1-0.6 wt%, Mn 1.0-2.5 wt%, and B 0.001-0.006 wt%. The mechanical properties of the substrate after hot stamping are: tensile strength 1300-1650 MPa, yield strength 950-1250 MPa, and elongation after fracture ≥4%.

[0030] When the strength of the substrate after hot stamping is 1800-2100 MPa, the substrate comprises the following components: C 0.28-0.38 wt%, Si 0.2-0.8 wt%, Mn 0.3-2.5 wt%, and B 0.001-0.006 wt%. The mechanical properties of the substrate after hot stamping are: tensile strength 1800-2100 MPa, yield strength 1200-1500 MPa, and elongation after fracture ≥4%.

[0031] When the strength of the substrate after hot stamping is 1000-1200 MPa, the substrate comprises the following components: C 0.05-0.14 wt%, Si 0.1-0.8 wt%, Mn 1.0-2.5 wt%, and B 0.001-0.006 wt%. The mechanical properties of the substrate after hot stamping are: tensile strength 1000-1200 MPa, yield strength 500-950 MPa, and elongation after fracture ≥5%.

[0032] When the strength of the substrate after hot stamping is 500-800 MPa, the substrate comprises the following components: C 0.05-0.14 wt%, Si 0.01-0.6 wt%, Mn 0.4-2.0 wt%, B ≤0.001 wt%, and the mechanical properties of the substrate after hot stamping are: tensile strength 1300-1650 MPa, yield strength 950-1250 MPa, and elongation after fracture ≥8%.

[0033] Based on the same inventive concept, a second aspect of this application provides a method for preparing a welded plate, wherein a first coated steel plate and a second coated steel plate are welded together; wherein the thickness and / or the strength after hot stamping of the first coated steel plate is different from that of the second coated steel plate, the first coated steel plate includes a first coating, the second coated steel plate includes a second coating, the thickness of the first coating is different from that of the second coating, and the first coated steel plate and the second coated steel plate are connected.

[0034] Furthermore, the welding speed of the weld is 2 to 30 m / min.

[0035] Based on the same inventive concept, a third aspect of this application provides a hot-formed component for a welded plate, wherein the hot-formed component is obtained by hot stamping of a welded plate as described in any of the first aspects or any of the second aspects.

[0036] Based on the same inventive concept, the fourth aspect of this application provides a method for preparing a thermoformed component of a welded plate, comprising the following steps:

[0037] The welded plate obtained by the preparation method described in any of the first aspects or the second aspects above is subjected to heating and hot stamping in sequence to obtain the thermoformed component of the welded plate.

[0038] Furthermore, the heating step is carried out in a roller hearth furnace or a box furnace, and the maximum heating temperature is 850-950°C;

[0039] Furthermore, in the hot stamping (i.e. quenching and cooling) step, mold cooling is used, and the cooling rate is 10-100℃ / s;

[0040] Furthermore, in the laser welding step, the welding speed is 2-30 m / min, including welding after partial peeling of the coating, welding with various welding wires added, and / or direct welding without treatment.

[0041] Based on the same inventive concept, the fifth aspect of this application provides a vehicle, including any one of the following (1) to (4):

[0042] (1) The welded plate described in any of the first aspects above;

[0043] (2) The welded plate prepared by any of the preparation methods described in the second aspect above;

[0044] (3) The hot-formed component of the welded plate described in the third aspect above;

[0045] (4) The hot-formed component of the welded plate prepared by any of the preparation methods in the fourth aspect above.

[0046] As can be seen from the above, the welded plate, the hot-formed component of the welded plate, the preparation method thereof, and the vehicle provided in this application, through experimental verification, demonstrate that by adjusting the coating thickness of coated steel plates with different thicknesses and / or different post-hot stamping strengths, different coated steel plates can achieve full austenitization in a substantially similar time. This ensures that all coated steel plates achieve full austenitization while avoiding prolonged overheating of thinner or weaker coated steel plates, fundamentally solving the problem of incomplete austenite transformation or overheating caused by coated steel plates of different thicknesses and / or different post-hot stamping strengths under the same heating time. Attached Figure Description

[0047] To more clearly illustrate the technical solutions in the embodiments of this application or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of this application. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0048] Figure 1This is a heating-cooling curve of the welded plate described in Embodiment 5 of this application;

[0049] Figure 2 The electron microscope images of the microstructure and coating of the first and second coated steel plates after heating and hot stamping of the welded plate described in Embodiment 5 of this application are shown.

[0050] Figure 3 This is a heating-cooling curve of the laser-welded plate described in Embodiment 6 of this application;

[0051] Figure 4 The image shows the microstructure and coating of the first and second coated steel plates after heating and hot stamping of the welded plate described in Embodiment 6 of this application. Detailed Implementation

[0052] To better understand the above-mentioned objectives, features, and advantages of this disclosure, the solutions disclosed herein will be further described below. It should be noted that, unless otherwise specified, the embodiments and features described herein can be combined with each other.

[0053] Numerous specific details are set forth in the following description in order to provide a full understanding of this disclosure, but this disclosure may also be implemented in other ways different from those described herein; obviously, the embodiments in the specification are only some, and not all, of the embodiments of this disclosure.

[0054] As described in the background section, many hot-formed parts of automobile bodies are obtained by laser welding various aluminum-silicon coated steel sheets of different thicknesses or strengths, followed by sequential heating and hot stamping. During the heating process, coated steel sheets of different thicknesses or strengths need to be heated at the same temperature for the same amount of time, ensuring uniform heating and complete austenitization. However, due to the different heating rates of coated steel sheets of varying thicknesses or strengths, thinner or weaker coated steel sheets heat faster and require less time to achieve complete austenitization, while thicker or stronger coated steel sheets heat slower and require more time. Heating coated steel sheets of different thicknesses or strengths at the same temperature for the same amount of time may lead to incomplete austenite transformation or overheating.

[0055] Based on the above problems, this application provides a welded plate that, by adjusting the thickness of the coating on different coated steel plates, enables the different coated steel plates to achieve full austenitization in a substantially similar time, fundamentally solving the problem of incomplete austenite transformation or overheating caused by different coated steel plates heating for the same time.

[0056] Specifically, by reducing the thickness of the first coating on the thicker first coated steel plate, the heating time required for the first coated steel plate to achieve full austenitization is shortened. At the same time, by increasing the thickness of the second coating on the thinner second coated steel plate, the heating time required for the second coated steel plate to achieve full austenitization is extended. Ultimately, the heating times for the first coated steel plate and the second coated steel plate to achieve full austenitization are basically the same, avoiding the problems of incomplete austenite transformation or overheating in different coated steel plates.

[0057] Based on this, the first aspect of this application provides a welded plate, comprising: a first coated steel plate and a second coated steel plate, wherein the thickness and / or the strength after hot stamping of the first coated steel plate are different from those of the second coated steel plate, the first coated steel plate includes a first coating, the second coated steel plate includes a second coating, the thickness of the first coating is different from that of the second coating, and the first coated steel plate and the second coated steel plate are connected by laser welding.

[0058] In some embodiments, the thickness of the first coating is 2 to 15 μm. For example, the thickness of the first coating can be 2 μm, 3 μm, 4 μm, 5 μm, 6 μm, 7 μm, 8 μm, 9 μm, 10 μm, 11 μm, 12 μm, 13 μm, 14 μm, 15 μm, etc.

[0059] In some embodiments, the thickness of the second coating is 18–37 μm. For example, the thickness of the second coating is 18 μm, 19 μm, 20 μm, 21 μm, 22 μm, 23 μm, 24 μm, 25 μm, 26 μm, 27 μm, 28 μm, 29 μm, 30 μm, 31 μm, 32 μm, 33 μm, 34 μm, 35 μm, 36 μm, 37 μm, etc.

[0060] In some embodiments, the thickness of the first coated steel plate is greater than 1.8 mm. For example, the thickness of the first coated steel plate can be 1.81 mm, 1.85 mm, 1.9 mm, 2.0 mm, 2.1 mm, 2.2 mm, 2.3 mm, 2.4 mm, 2.5 mm, 2.6 mm, 2.7 mm, 2.8 mm, 2.9 mm, 3.0 mm, etc. Correspondingly, when the thickness of the first coated steel plate is greater than 1.8 mm, the difference between the thickness of the first coated steel plate and the thickness of the second coated steel plate is 0 to 0.6 mm. For example, this difference can be 0.6 mm, 0.55 mm, 0.5 mm, 0.45 mm, 0.4 mm, 0.35 mm, 0.3 mm, 0.25 mm, 0.2 mm, 0.15 mm, 0.1 mm, 0.05 mm, 0 mm, etc.

[0061] In some embodiments, the thickness of the first coated steel plate is between 1.1 and 1.8 mm. For example, the thickness of the first coated steel plate can be 1.1 mm, 1.15 mm, 1.2 mm, 1.25 mm, 1.3 mm, 1.35 mm, 1.4 mm, 1.45 mm, 1.5 mm, 1.55 mm, 1.6 mm, 1.65 mm, 1.7 mm, 1.75 mm, 1.8 mm, etc. Correspondingly, when the thickness of the first coated steel plate is between 1.1 and 1.8 mm, the difference between the thickness of the first coated steel plate and the thickness of the second coated steel plate is 0 to 0.4 mm. For example, this difference can be 0.4 mm, 0.35 mm, 0.3 mm, 0.25 mm, 0.2 mm, 0.15 mm, 0.1 mm, 0.05 mm, 0 mm, etc.

[0062] In some embodiments, the strength of the first coated steel sheet after hot stamping can be 1300MPa, 1400MPa, 1500MPa, 1600MPa, 1650MPa, 1700MPa, 1800MPa, 1900MPa, 2000MPa, 2100MPa, etc.

[0063] In some embodiments, the strength of the second coated steel sheet after hot stamping can be 500MPa, 600MPa, 700MPa, 800MPa, 900MPa, 1000MPa, 1100MPa, 1200MPa, 1300MPa, 1400MPa, 1500MPa, 1600MPa, 1650MPa, 1700MPa, etc.

[0064] In some embodiments, both the first coating and the second coating are silicon-aluminum coatings, and the aluminum content in the first coating and the second coating is greater than or equal to 85 wt%. For example, the aluminum content can be 85 wt%, 86 wt%, 87 wt%, 88 wt%, 89 wt%, 90 wt%, 91 wt%, 92 wt%, 93 wt%, 94 wt%, 95 wt%, etc.

[0065] In some embodiments, the silicon content in the first and second coatings is 5 to 11 wt%. For example, the silicon content can be 5 wt%, 6 wt%, 7 wt%, 8 wt%, 9 wt%, 10 wt%, or 11 wt%.

[0066] In some embodiments, the iron content in the first and second coatings is less than or equal to 4 wt%. Exemplary examples include 4 wt%, 3 wt%, 2 wt%, 1 wt%, and 0 wt%.

[0067] In some embodiments, the strength, element content, and mechanical properties of the first substrate and the second substrate after hot stamping all meet the following conditions (for ease of description, the first substrate and the second substrate are collectively referred to as substrates):

[0068] When the strength of the substrate after hot stamping is 1300-1650 MPa, the substrate comprises the following components: C 0.18-0.26 wt%, Si 0.1-0.6 wt%, Mn 1.0-2.5 wt%, and B 0.001-0.006 wt%. For example, the content of C can be 0.18wt%, 0.19wt%, 0.20wt%, 0.21wt%, 0.22wt%, 0.23wt%, 0.24wt%, 0.25wt%, 0.26wt%, etc.; the content of Si can be 0.1wt%, 0.2wt%, 0.3wt%, 0.4wt%, 0.5wt%, 0.6wt%, etc.; the content of Mn can be 1.0wt%, 2.0wt%, 2.5wt%, etc.; and the content of B can be 0.001wt%, 0.002wt%, 0.003wt%, 0.004wt%, 0.005wt%, 0.006wt%, etc.

[0069] When the strength of the substrate after hot stamping is 1800-2100 MPa, the substrate comprises the following components: C 0.28-0.38 wt%, Si 0.2-0.8 wt%, Mn 0.3-2.5 wt%, and B 0.001-0.006 wt%. For example, the content of C can be 0.28wt%, 0.29wt%, 0.30wt%, 0.31wt%, 0.32wt%, 0.33wt%, 0.34wt%, 0.35wt%, 0.36wt%, 0.37wt%, 0.38wt%, etc.; the content of Si can be 0.2wt%, 0.3wt%, 0.4wt%, 0.5wt%, 0.6wt%, 0.7wt%, 0.8wt%, etc.; the content of Mn can be 0.3wt%, 0.5wt%, 0.8wt%, 1.0wt%, 2.0wt%, 2.5wt%, etc.; and the content of B can be 0.001wt%, 0.002wt%, 0.003wt%, 0.004wt%, 0.005wt%, 0.006wt%, etc.

[0070] When the strength of the substrate after hot stamping is 1000-1200 MPa, the substrate comprises the following components: C 0.05-0.14 wt%, Si 0.1-0.8 wt%, Mn 1.0-2.5 wt%, and B 0.001-0.006 wt%. For example, the content of C can be 0.05wt%, 0.06wt%, 0.07wt%, 0.08wt%, 0.09wt%, 0.10wt%, 0.11wt%, 0.12wt%, 0.13wt%, 0.24wt%, etc.; the content of Si can be 0.1wt%, 0.2wt%, 0.3wt%, 0.4wt%, 0.5wt%, 0.6wt%, 0.7wt%, 0.8wt%, etc.; the content of Mn can be 1.0wt%, 2.0wt%, 2.5wt%, etc.; and the content of B can be 0.001wt%, 0.002wt%, 0.003wt%, 0.004wt%, 0.005wt%, 0.006wt%, etc.

[0071] A second aspect of this application provides a method for preparing a welded plate, wherein a first coated steel plate and a second coated steel plate are welded together. The welding speed of the welded plate is 2 to 30 m / min.

[0072] The third aspect of this application provides a hot-formed component for a welded plate, wherein the hot-formed component is obtained by hot stamping of the welded plate described in either the first or second aspect above.

[0073] The fourth aspect of this application provides a method for preparing a hot-formed component from a welded sheet, using coated steel sheet as raw material. Specifically, it includes the following steps:

[0074] The welded plate obtained by the preparation method described in any of the first aspects or the second aspects above is subjected to heating and hot stamping in sequence to obtain the thermoformed component of the welded plate.

[0075] It should be noted that the preparation methods and hot-formed components of the welded plates provided in the second to fourth aspects of this application all have the corresponding technical effects of the first aspect, and will not be elaborated here.

[0076] The fifth aspect of this application provides a vehicle comprising any one of the following (1) to (4):

[0077] (1) The welded plate described in any of the first aspects above;

[0078] (2) The welded plate prepared by any of the preparation methods described in the second aspect above;

[0079] (3) The hot-formed component of the welded plate described in the third aspect above;

[0080] (4) The hot-formed component of the welded plate prepared by any of the preparation methods in the fourth aspect above.

[0081] It should be noted that the vehicle provided in the fifth aspect of this application has the corresponding technical effects of the above aspects, which will not be elaborated here.

[0082] The present invention will now be described with reference to specific embodiments. It should be noted that these embodiments are merely descriptive and do not limit the present invention in any way.

[0083] Example 1

[0084] A welded plate is provided, comprising: a first coated steel plate and a second coated steel plate, wherein the thickness and / or the strength after hot stamping of the first coated steel plate are different from those of the second coated steel plate, the first coated steel plate includes a first coating, the second coated steel plate includes a second coating, the thickness of the first coating is different from that of the second coating, and the first coated steel plate and the second coated steel plate are connected by laser welding, wherein the welded plate is a laser welded plate.

[0085] The thickness of the first coating is 15 μm, and the thickness of the second coating is 18 μm. Both the first and second coatings are silicon-aluminum coatings, and the aluminum content in both coatings is greater than or equal to 85 wt%.

[0086] The thickness of the first coated steel sheet is 2.0 mm, and the strength of the first coated steel sheet after hot stamping is 1500 MPa. The thickness of the second coated steel sheet is 2.0 mm, and the strength of the second coated steel sheet after hot stamping is 1200 MPa. The difference between the thickness of the first coated steel sheet and the thickness of the second coated steel sheet is 0 mm.

[0087] Example 2

[0088] A welded plate is provided, comprising: a first coated steel plate and a second coated steel plate, wherein the thickness and / or the strength after hot stamping of the first coated steel plate differs from that of the second coated steel plate; the first coated steel plate includes a first coating; the second coated steel plate includes a second coating; the thickness of the first coating differs from that of the second coating; the first coated steel plate and the second coated steel plate are joined together by laser welding; the welded plate is a laser-welded plate.

[0089] Wherein, the thickness of the first coated steel plate is greater than the thickness of the second coated steel plate, and the thickness of the first coating is less than the thickness of the second coating.

[0090] The thickness of the first coating is 15 μm, and the thickness of the second coating is 37 μm. Both the first and second coatings are silicon-aluminum coatings, and the aluminum content in both coatings is greater than or equal to 85 wt%.

[0091] The thickness of the first coated steel sheet is 2.0 mm, and the strength of the first coated steel sheet after hot stamping is 1500 MPa. The thickness of the second coated steel sheet is 1.4 mm, and the strength of the second coated steel sheet after hot stamping is 1500 MPa. The difference between the thickness of the first coated steel sheet and the thickness of the second coated steel sheet is 0.6 mm.

[0092] Example 3

[0093] A welded plate is provided, comprising: a first coated steel plate and a second coated steel plate, wherein the thickness and / or the strength after hot stamping of the first coated steel plate differs from that of the second coated steel plate; the first coated steel plate includes a first coating; the second coated steel plate includes a second coating; the thickness of the first coating differs from that of the second coating; the first coated steel plate and the second coated steel plate are joined together by laser welding; the welded plate is a laser-welded plate.

[0094] The thickness of the first coated steel plate is greater than the thickness of the second coated steel plate, and the thickness of the first coating is less than the thickness of the second coating.

[0095] The thickness of the first coating is 5 μm, and the thickness of the second coating is 19 μm. Both the first and second coatings are silicon-aluminum coatings, and the aluminum content in both coatings is greater than or equal to 85 wt%.

[0096] The thickness of the first coated steel sheet is 1.1 mm, and the strength of the first coated steel sheet after hot stamping is 1500 MPa. The thickness of the second coated steel sheet is 0.8 mm, and the strength of the second coated steel sheet after hot stamping is 1500 MPa. The difference between the thickness of the first coated steel sheet and the thickness of the second coated steel sheet is 0.3 mm.

[0097] Example 4

[0098] A welded plate is provided, comprising: a first coated steel plate and a second coated steel plate, wherein the thickness and / or the strength after hot stamping of the first coated steel plate differs from that of the second coated steel plate; the first coated steel plate includes a first coating; the second coated steel plate includes a second coating; the thickness of the first coating differs from that of the second coating; the first coated steel plate and the second coated steel plate are joined together by laser welding; the welded plate is a laser-welded plate.

[0099] Wherein, the thickness of the first coated steel plate is greater than the thickness of the second coated steel plate, and the thickness of the first coating is less than the thickness of the second coating.

[0100] The thickness of the first coating is 15 μm, and the thickness of the second coating is 33 μm. Both the first and second coatings are silicon-aluminum coatings, and the aluminum content in both coatings is greater than or equal to 85 wt%.

[0101] The thickness of the first coated steel sheet is 1.8 mm, and the strength of the first coated steel sheet after hot stamping is 1500 MPa. The thickness of the second coated steel sheet is 1.6 mm, and the strength of the second coated steel sheet after hot stamping is 1500 MPa. The difference between the thickness of the first coated steel sheet and the thickness of the second coated steel sheet is 0.2 mm.

[0102] Example 5

[0103] A welded plate is provided, comprising: a first coated steel plate and a second coated steel plate, wherein the thickness and / or the strength after hot stamping of the first coated steel plate differs from that of the second coated steel plate; the first coated steel plate includes a first coating; the second coated steel plate includes a second coating; the thickness of the first coating differs from that of the second coating; the first coated steel plate and the second coated steel plate are joined together by laser welding; the welded plate is a laser-welded plate.

[0104] The thickness of the first coating is 10 μm, and the thickness of the second coating is 30 μm. Both the first and second coatings are silicon-aluminum coatings, and the aluminum content in both coatings is greater than or equal to 85 wt%.

[0105] The first coated steel sheet has a strength of 1500 MPa after hot stamping and a thickness of 1.9 mm. The second coated steel sheet has a strength of 800 MPa after hot stamping and a thickness of 1.3 mm. The difference between the thickness of the first coated steel sheet and the thickness of the second coated steel sheet is 0.6 mm.

[0106] Example 6

[0107] A welded plate is provided, comprising: a first coated steel plate and a second coated steel plate, wherein the thickness and / or the strength after hot stamping of the first coated steel plate differs from that of the second coated steel plate; the first coated steel plate includes a first coating; the second coated steel plate includes a second coating; the thickness of the first coating differs from that of the second coating; the first coated steel plate and the second coated steel plate are joined together by laser welding; the welded plate is a laser-welded plate.

[0108] The thickness of the first coating is 15 μm, and the thickness of the second coating is 33 μm. Both the first and second coatings are silicon-aluminum coatings, and the aluminum content in both coatings is greater than or equal to 85 wt%.

[0109] The first coated steel sheet has a strength of 1500 MPa after hot stamping, and its thickness is 1.9 mm. The second coated steel sheet has a strength of 1500 MPa after hot stamping, and its thickness is 1.5 mm. The difference between the thickness of the first coated steel sheet and the thickness of the second coated steel sheet is 0.4 mm.

[0110] Example 7

[0111] A welded plate is provided, comprising: a first coated steel plate and a second coated steel plate, wherein the thickness and / or the strength after hot stamping of the first coated steel plate differs from that of the second coated steel plate; the first coated steel plate includes a first coating; the second coated steel plate includes a second coating; the thickness of the first coating differs from that of the second coating; the first coated steel plate and the second coated steel plate are joined together by laser welding; the welded plate is a laser-welded plate.

[0112] The thickness of the first coating is 15 μm, and the thickness of the second coating is 33 μm. Both the first and second coatings are silicon-aluminum coatings, and the aluminum content in both coatings is greater than or equal to 85 wt%.

[0113] The first coated steel sheet has a strength of 1500 MPa after hot stamping, and its thickness is 1.5 mm. The second coated steel sheet has a strength of 1500 MPa after hot stamping, and its thickness is 1.1 mm. The difference between the thickness of the first coated steel sheet and the thickness of the second coated steel sheet is 0.4 mm.

[0114] Example 8

[0115] A welded plate is provided, comprising: a first coated steel plate and a second coated steel plate, wherein the thickness and / or the strength after hot stamping of the first coated steel plate differs from that of the second coated steel plate; the first coated steel plate includes a first coating; the second coated steel plate includes a second coating; the thickness of the first coating differs from that of the second coating; the first coated steel plate and the second coated steel plate are joined together by laser welding; the welded plate is a laser-welded plate.

[0116] The thickness of the first coating is 10 μm, and the thickness of the second coating is 30 μm. Both the first and second coatings are silicon-aluminum coatings, and the aluminum content in both coatings is greater than or equal to 85 wt%.

[0117] The first coated steel sheet has a strength of 1500 MPa after hot stamping, and a thickness of 1.5 mm. The second coated steel sheet has a strength of 800 MPa after hot stamping, and a thickness of 1.3 mm. The difference between the thicknesses of the first and second coated steel sheets is 0.2 mm.

[0118] Comparative Example 1

[0119] A welded plate is provided, which is the same as in Example 2, except that the thickness of the second coated steel plate is 1.0 mm.

[0120] Comparative Example 2

[0121] A welding board is provided, which is the same as in Example 5, except that the thickness of the first coating is 30 μm.

[0122] Comparative Example 3

[0123] A welding board is provided, which is the same as that in Example 6, except that the thickness of the first coating is 33 μm.

[0124] Comparative Example 4

[0125] A welding board is provided, which is the same as in Example 2, except that the thickness of the first coating is 2 μm.

[0126] Comparative Example 5

[0127] A welding board is provided, which is the same as in Example 2, except that the thickness of the first coating is 20 μm.

[0128] Comparative Example 6

[0129] A welding board is provided, which is the same as in Example 2, except that the thickness of the second coating is 10 μm.

[0130] Comparative Example 7

[0131] A welding board is provided, which is the same as in Example 8, except that the thickness of the second coating is 45 μm.

[0132] The welded plates from the above embodiments and comparative examples are sequentially heated and hot-stamped to obtain the corresponding hot-formed welded plate components. Specifically, the heating step is carried out in a box furnace, with an initial heating temperature of 30°C and a final heating temperature (maximum temperature) of 950°C; in the hot-stamping (i.e., quenching and cooling) step, mold cooling is used, with a cooling rate of 50°C / s; in the laser welding step, the welding speed is 15 m / min.

[0133] During the heating process, the time required for the first and second coated steel plates to be heated to the highest temperature was monitored, and the martensite content in the microstructure of the first and second coated steel plates in the prepared hot-formed welded plate was determined. The monitoring and measurement data are detailed in Table 1 below.

[0134] Table 1. List of relevant data for the embodiments and comparative examples.

[0135]

[0136]

[0137] It is worth noting that the time difference ratio in the table above is calculated using the formula M = (T1 - T2) / T2; where M represents the time difference ratio; T1 represents the larger of the heating times for the first and second coated steel plates; and T2 represents the smaller of the heating times for the first and second coated steel plates. A smaller time difference ratio indicates a shorter overheating time, while a larger ratio indicates a longer overheating time.

[0138] When heating the laser-welded plates, the total heating time is the greater of the heating times for the first and second coated steel plates, ensuring complete austenite transformation in both plates. Therefore, the coated steel plate with a shorter heating time may experience slight overheating. However, as long as the time difference ratio remains within the specified range, it will not affect the toughness or weldability of the overheated coated steel plate.

[0139] Industry standards stipulate that only thermoformed parts that meet the following two conditions can be used in automobile bodies.

[0140] Condition 1: During the process of heating the thermoforming parts of the laser-welded plate, the time difference ratio is <20%;

[0141] Condition 2: The martensite content in the microstructure of all coated steel sheets with a strength of 1200MPa or higher in the hot-formed parts of the laser-welded plate after hot stamping is >90% (since the microstructure of coated steel sheets with a strength of less than 1200MPa is variable, no limitation is made).

[0142] As shown in Table 1 above, in each embodiment, based on the thickness and strength of the first and second coated steel plates, the thicknesses of the corresponding first and second coatings are reasonably adjusted. By reducing the thickness of the first coating on the thicker first coated steel plate, the heating time required for the first coated steel plate to achieve full austenitization is shortened. Simultaneously, by increasing the thickness of the second coating on the thinner second coated steel plate, the heating time required for the second coated steel plate to achieve full austenitization is extended. Ultimately, the heating times for the first and second coated steel plates to achieve full austenitization are essentially the same, with a time difference ratio of less than 5%, far below the industry standard. (Reference) Figure 1 and Figure 3 As shown, the time required for the first and second coated steel sheets to heat to the peak temperature (950℃) is basically the same, proving that this application can significantly reduce the overheating time of coated steel sheets with shorter heating times, avoiding the impact of prolonged overheating on the toughness and weldability of the coated steel sheets. Meanwhile, the martensite content of both the first and second coated steel sheets after hot stamping is >90% (see the microstructure and coating of the first and second coated steel sheets after hot stamping). Figure 2 and Figure 4 As shown in the figure, it proves that the austenite transformation of the first-coated steel plate and the second-coated steel plate is complete.

[0143] Compared with Example 2, in Comparative Example 1, the thickness difference between the second coated steel plate and the first coated steel plate is too large, resulting in an excessively thin second coating and a short heating time. This leads to a large difference between the heating time of the first coated steel plate and the heating time of the second coated steel plate, with a time difference ratio of 40%. Ultimately, this results in an excessively long overheating time (63s) for the second coated steel plate, which seriously affects the toughness and weldability of the second coated steel plate.

[0144] Comparative Example 2 uses existing laser-welded plates in the industry, where the thickness of the first and second coatings is the same. Because the thicknesses of the first and second coatings differ, the required heating times also differ, resulting in a longer overheating time (46s) for the second coating and a larger time difference ratio (24%), which affects the toughness and weldability of the second coating. In Example 5, compared to Comparative Example 2, simply reducing the thickness of the first coating reduces the heating time of the first coating, thereby significantly reducing the overheating time of the second coating (14s), thus avoiding any impact on the toughness and weldability of the second coating.

[0145] Comparative Example 3 also uses existing laser-welded plates in the industry, where the thickness of the first coating and the thickness of the second coating are the same. Because the thicknesses of the first and second coatings differ, the required heating times also differ, resulting in a longer overheating time (41s) for the second coating and a larger time difference ratio (20.7%), which affects the toughness and weldability of the second coating. In Example 6, compared to Comparative Example 3, simply reducing the thickness of the first coating reduces the heating time of the first coating, thereby significantly reducing the overheating time of the second coating (4s), thus avoiding any impact on the toughness and weldability of the second coating.

[0146] Compared with Example 2, in Comparative Example 4, the thickness of the first coating was too small, resulting in a short heating time for the first coated steel plate, even shorter than the heating time for the second coated steel plate. This ultimately led to a prolonged overheating of the first coated steel plate, severely affecting its toughness and weldability.

[0147] Compared with Example 2, in Comparative Example 5, the thickness of the first coating is too large, resulting in a longer heating time for the first coated steel plate, which cannot be balanced with the heating time of the second coated steel plate, ultimately leading to a large time difference ratio and an excessively long overheating time for the second coated steel plate.

[0148] Compared with Example 2, in Comparative Example 6, the thickness of the second coating was too small, resulting in a short heating time for the second coated steel plate. This ultimately led to a prolonged overheating of the second coated steel plate, which severely affected its toughness and weldability.

[0149] Compared with Example 8, in Comparative Example 7, the thickness of the second coating was too large, resulting in a long heating time for the second coated steel plate. This ultimately led to a prolonged overheating of the first coated steel plate, affecting its performance.

[0150] In summary, the welded steel plate, the hot-formed component of the welded steel plate, the preparation method thereof, and the vehicle provided in this application, through experimental verification, demonstrate that by adjusting the coating thickness of coated steel plates with different thicknesses and / or strengths, different coated steel plates can achieve full austenitization in approximately the same amount of time. This ensures that different coated steel plates achieve full austenitization while avoiding overheating of thinner or weaker coated steel plates, fundamentally solving the problem of incomplete austenite transformation or overheating caused by different coated steel plates heating for the same time.

[0151] It should be noted that, in this document, relational terms such as "first" and "second" are used merely to distinguish one entity or operation from another, and do not necessarily require or imply any such actual relationship or order between these entities or operations. Furthermore, the term "comprising" or any other variations thereof is intended to cover non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements includes not only those elements but also other elements not expressly listed, or elements inherent to such a process, method, article, or apparatus. Without further limitations, an element defined by the phrase "comprising one..." does not exclude the presence of other identical elements in the process, method, article, or apparatus that includes said element.

Claims

1. A welded plate, characterized in that, include: A first coated steel plate and a second coated steel plate, wherein the thickness and / or the strength after hot stamping of the first coated steel plate are different from those of the second coated steel plate, the first coated steel plate includes a first coating, the second coated steel plate includes a second coating, the thickness of the first coating is different from that of the second coating, the first coated steel plate and the second coated steel plate are connected by welding, the thickness of the first coated steel plate is greater than that of the second coated steel plate, and the thickness of the first coating is less than that of the second coating.

2. The welded plate as described in claim 1, characterized in that, The thickness of the first coating is 4~15um, and the thickness of the second coating is 18~37um.

3. The welded plate as described in claim 1, characterized in that, In response to determining that the thickness of the first coated steel sheet is greater than 1.8 mm, the difference between the thickness of the first coated steel sheet and the thickness of the second coated steel sheet is 0~0.6 mm. In response to determining that the thickness of the first coated steel sheet is between 1.1 and 1.8 mm, the difference between the thickness of the first coated steel sheet and the thickness of the second coated steel sheet is 0 to 0.4 mm.

4. The welded plate as described in claim 1, characterized in that, In response to determining that the thickness of the first coated steel sheet is greater than 1.8 mm and the strength of the second coated steel sheet after hot stamping is greater than or equal to 1000 MPa, the difference between the thickness of the first coated steel sheet and the thickness of the second coated steel sheet is 0~0.6 mm. In response to determining that the thickness of the first coated steel sheet is greater than 1.8 mm and the strength of the second coated steel sheet after hot stamping is less than 1000 MPa, the difference between the thickness of the first coated steel sheet and the thickness of the second coated steel sheet is 0.2~0.6 mm.

5. The welded plate as described in claim 1, characterized in that, In response to determining that the thickness of the first coated steel sheet is between 1.1 and 1.8 mm and the strength of the second coated steel sheet after hot stamping is greater than or equal to 1000 MPa, the difference between the thickness of the first coated steel sheet and the thickness of the second coated steel sheet is 0 to 0.4 mm. In response to determining that the thickness of the first coated steel sheet is between 1.1 and 1.8 mm and the strength of the second coated steel sheet after hot stamping is less than 1000 MPa, the difference between the thickness of the first coated steel sheet and the thickness of the second coated steel sheet is 0.2 to 0.4 mm.

6. The welded plate as described in claim 1, characterized in that, Both the first coating and the second coating are silicon-aluminum coatings, and the aluminum content in the first coating and the second coating is greater than or equal to 85 wt%.

7. A method for preparing a welded plate, characterized in that: The first coated steel plate and the second coated steel plate are welded together by splicing; wherein the thickness and / or the strength after hot stamping of the first coated steel plate are different from those of the second coated steel plate, the first coated steel plate includes a first coating, the second coated steel plate includes a second coating, the thickness of the first coating is different from that of the second coating, the thickness of the first coated steel plate is greater than that of the second coated steel plate, and the thickness of the first coating is less than that of the second coating.

8. The preparation method according to claim 7, characterized in that, The welding speed for the assembly is 2~30m / min.

9. A thermoformed component made of welded plates, characterized in that, The hot-formed component of the welded plate is obtained by hot stamping of the welded plate as described in any one of claims 1 to 6 or the welded plate as described in any one of claims 7 to 8.

10. A method for preparing a hot-formed component from a welded plate, characterized in that: Includes the following steps: The welded plate according to any one of claims 1 to 6 or the welded plate prepared by any one of claims 7 to 8 is subjected to heating and hot stamping in sequence to obtain the thermoformed component of the welded plate.

11. The preparation method according to claim 10, characterized in that, The heating step is carried out in a roller hearth furnace or a box furnace, and the maximum heating temperature is 850~950℃.

12. The preparation method according to claim 10, characterized in that, In the hot stamping step, mold cooling is used, and the cooling rate is 10~100℃ / s.

13. A vehicle, characterized in that, Including any one of the following (1) to (4): (1) The welded plate according to any one of claims 1 to 6; (2) The welded plate prepared by the preparation method according to any one of claims 7 to 8; (3) The hot-formed component of the welded plate as described in claim 9; (4) The hot-formed component of the welded plate obtained by any one of the preparation methods of claims 10 to 12.

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