Structural component for a vehicle and method

Abstract

The present disclosure relates to a structural component for a vehicle frame, the structural component being at least partially configured for supporting a compressive load. The structural component includes a main member extending in a longitudinal direction from a load receiving end to an opposite end. Further, the primary member includes a primary soft region having a lower mechanical property than other regions of the primary member. Further, the main soft zone includes first and second portions having substantially constant first and second mechanical properties, respectively. The mechanical property of the first part is lower than that of the second part.

Description

[0001] This application claims the benefit of EP22382876.5, filed on September 22, 2022. Technical Field

[0002] The present disclosure relates to a structural component for a vehicle frame, which is at least partially configured to support a compressive load. Background Art

[0003] Vehicles such as automobiles include a structural framework designed to withstand the loads that a vehicle may experience during its service life. The structural framework is further designed to withstand and absorb impacts in the case of a collision with, for example, other automobiles or road structures.

[0004] The automotive industry's demand for weight reduction has led to the development and implementation of lightweight materials or components, as well as related manufacturing processes and tools. The demand for weight reduction is particularly driven by the goal of reducing CO 2 emissions. The increasing concern for occupant safety has also led to the adoption of materials that improve vehicle integrity during a collision while also improving energy absorption.

[0005] A process called Hot Forming Die Quenching (HFDQ) typically uses boron steel sheets to manufacture stamped parts with Ultra High Strength Steel (UHSS) properties, having a tensile strength of, for example, 1500 MPa or 2000 MPa or even higher. The increase in strength allows the use of thinner gauge materials, which results in weight reduction compared to conventional cold-stamped low-carbon steel parts. Throughout the present disclosure, UHSS can be considered as steel having an ultimate tensile strength of 1000 MPa or higher after a press hardening process.

[0006] In the HFDQ process, a blank to be hot formed can be heated to a predetermined temperature, such as the austenitization temperature or higher (and particularly between Ac3 and, for example, the evaporation temperature of the coating of the blank). A high-temperature furnace system can be used for this purpose. Depending on specific requirements, the high-temperature furnace system can be supplemented with additional heaters, such as induction heaters or infrared heaters. By heating the blank, the strength of the blank is reduced and its formability is increased, i.e., facilitating the hot stamping process.

[0007] There are several known Ultra High Strength Steels (UHSS) for hot stamping and hardening. The blank can be made of, for example, coated or uncoated boron steel, such as (22MnB5) commercially available from ArcelorMittal.

[0008] Hot Forming Die Quenching can also be referred to as "press hardening" or "hot stamping". These terms will be used interchangeably throughout the present disclosure.

[0009] Typical vehicle components that can be manufactured using the HFDQ process include: door beams, bumper beams, cross members / side rails, A / B pillar reinforcements, front and rear longitudinal beams, seat cross members, and roof longitudinal beams.

[0010] Hot forming of boron steel has become increasingly popular in the automotive industry due to its excellent strength and formability. As a result, many structural components that were traditionally cold formed from low-carbon steel have been replaced by hot-formed equivalents, which have a significantly increased strength. This allows for a reduction in material thickness (and thus weight) while maintaining the same strength. However, hot-formed components provide a very low level of ductility and energy absorption under the conditions in which they are formed.

[0011] To improve the ductility and energy absorption in specific regions of a component, it is known to introduce softer regions within the same component. This locally improves the ductility while generally maintaining the required high strength. By locally customizing the microstructure and mechanical properties of certain structural components such that they include regions with very high strength (very hard), i.e., high ultimate tensile strength and high yield strength, and regions with increased ductility (softer), i.e., lower ultimate tensile strength and lower yield strength and increased elongation before fracture, the overall energy absorption of these structural components can be improved and their structural integrity maintained during a collision scenario, and their overall weight can also be reduced. Such soft zones can also advantageously alter the kinematic behavior in the case where the component collapses under impact.

[0012] Known methods for creating regions of increased ductility ("soft zones") in the structural components of a vehicle include providing a tool comprising a pair of complementary upper and lower die units, each of which units has individual die elements (steel blocks). The blank to be hot formed is preheated to a predetermined temperature, such as the austenitizing temperature or higher, for example by means of a high-temperature furnace system, in order to reduce the strength, i.e., to facilitate the hot stamping process.

[0013] The die elements can be designed to operate at different temperatures so that different regions of the part formed during the quenching process have different cooling rates, and thus result in different material properties in the final product, such as soft regions that typically have a lower ultimate tensile strength and a lower yield strength but allow for a greater elongation before fracture. For example, one die element can be cooled so as to quench a corresponding region of the part being manufactured at a high cooling rate, and thus rapidly reduce the temperature of the part and obtain a hard martensitic microstructure. Another adjacent die element can be heated so as to ensure that a corresponding portion of the part being manufactured cools at a lower cooling rate so as to obtain a softer microstructure, including, for example, bainite, ferrite, and / or pearlite. When the part exits the die, such regions of the part can remain at a higher temperature than the rest of the part.

[0014] Other methods for obtaining hot-stamped parts with regions of different mechanical properties include, for example, customized heating or differential heating before stamping, and local heat treatment after the stamping process to change the local microstructure and obtain different mechanical properties. Further possible methods include using patchwork blanks and tailor welded blanks (TWBs) that combine different thicknesses and / or materials in the blank.

[0015] Several methods for differential heating before stamping are known. In an example, a nozzle or a group of nozzles can discharge a fluid stream, such as compressed cooling air, towards a portion of the blank to be cooled, for example, while the blank is still in the heating furnace. Other portions of the blank can be kept at a higher temperature. This enables obtaining a blank with a customized temperature distribution along its length and / or width. In some examples, the blank can undergo further heating in the heating furnace before being subjected to the stamping process.

[0016] In other examples, an infrared heater array can be used, which can be independently controlled to control the temperature along the blank.

[0017] Some elements of the structural framework of an automobile (e.g., front and rear longitudinal beams, seat cross-members, and roof longitudinal beams) can be specifically designed to support compressive loads. That is, these components are arranged such that they are subjected to compressive loads in the case of a standard collision scenario. These structural components and other structural components can have one or more regions that have a generally U-shaped (also referred to as "hat" shaped) cross-section. These structural components can be manufactured in various ways and can be made of various materials. Lightweight materials that improve energy absorption during a collision while still maintaining the integrity of the vehicle are desirable.

[0018] Throughout the present disclosure, a U-shaped cross-section can be understood to refer to a structural member that has a bottom wall and two side walls in cross-section (usually in a transverse plane substantially perpendicular to the longitudinal axis of the structural member). As is well known, a U-shaped cross-section has a good ratio of moment of inertia to weight. The two side walls can form an obtuse angle with the bottom wall, for example, between 90° and 135°. The two side walls can include outwardly extending side flanges. The bottom wall and the side walls can be substantially straight, but they can also include transition portions, curved portions, recesses, or protrusions.

[0019] In addition to the ultra-high-strength steel mentioned above, more ductile steel can be used in parts of the structural framework that need to absorb energy. Examples of ductile steel include 500, 1000 and CRL-340LA.

[0020] UHSS can exhibit a tensile strength of up to 1500 MPa, or even 2000 MPa or higher, especially after a press hardening operation. Once hardened, UHSS can have a martensitic microstructure. This microstructure can increase the maximum tensile strength and yield strength per unit weight.

[0021] Some ductile steels can also be heated and pressed (i.e., used in a hot stamping process), but do not have a martensitic microstructure after this process. Therefore, they will have a lower tensile strength and yield strength than UHSS, but they have a higher elongation at break.

[0022] Although ductile steel enables a structural component to absorb energy, it may not be easy to control and predict how a structural component may behave during a vehicle collision. Moreover, it may not be simple to enhance energy absorption while maintaining a certain structural integrity of the structural component.

[0023] The object of the present disclosure is to provide an improvement in the control of the deformation and energy absorption of a structural component for a vehicle frame when subjected to a load, especially a compressive load. Summary of the Invention

[0024] In a first aspect, there is provided a structural component for a vehicle frame. The structural component is at least partially configured to support a compressive load. The structural component includes a main member that extends along a longitudinal direction of the main member from a load receiving end to an opposite end. The main member includes a main soft zone that has lower mechanical properties than other zones of the main member. Further, the main soft zone includes a first portion having a substantially constant first mechanical property and a second portion having a substantially constant second mechanical property, wherein the first mechanical property is lower than the second mechanical property.

[0025] A main soft zone including a first part and a second part is introduced, where the first part and the second part have respective first mechanical properties and second mechanical properties, enabling the main component to effectively absorb energy during a collision while controlling the kinematics of deformation. When the structural component is subjected to a compressive load, the first part having lower mechanical properties than the second part can deform first, before the second part and before the rest of the main component. The main component can achieve absorbing more energy with a high predictability of deformation during compression. On the other hand, the rest of the main component with higher mechanical properties can provide a limitation to the deformation, such as retaining the interior space of the vehicle. Thus, the safety of vehicle passengers can be enhanced.

[0026] A compressive load can be understood as a load or a component of a load acting substantially parallel to the length of the structural component in a way that attempts to shorten the component. Components or regions in an automotive frame that may be particularly subject to compressive loads in different collision or impact scenarios include: front longitudinal beams, rear longitudinal beams, energy absorbers, roof longitudinal beams, and seat cross members. Thus, the examples disclosed herein can be particularly beneficial when used in such types of components.

[0027] Throughout this disclosure, "configured at least in part to support a compressive load" can be understood to mean that a part of the component or the entire component is expected to primarily absorb a compressive load in the event of an impact or collision. That is, even though other loads may also occur, the compressive load is expected to be higher.

[0028] Furthermore, throughout this disclosure, a reference to "the mechanical properties of a part" can be understood as the mechanical properties of the material forming the part. Thus, unless otherwise specified, comparisons of the mechanical properties of parts, components, etc. relate to the material, rather than its geometry or other characteristics.

[0029] Higher mechanical properties can be understood herein as higher ultimate tensile strength and / or higher yield strength, while lower mechanical properties can be understood as lower ultimate tensile strength and / or lower yield strength. The ultimate tensile strength and yield strength are considered herein as material properties of the material after the manufacturing process. The ultimate tensile strength and yield strength can be determined in a standardized tensile strength test, using, for example, A30, A50, or A80 specimens in a quasi-static load test.

[0030] The comparison between lower mechanical properties and higher mechanical properties should be made using the same test conditions and specimen sizes. To compare the yield strengths of different parts, specimens formed of the same material as the part of the structural component (e.g., the part of the soft zone) can be prepared and tested in a Universal Testing Machine (UTM).

[0031] Throughout this disclosure, a "portion having substantially constant mechanical properties" can be considered to be a portion made of the same material that has been subjected to the same heat treatment. The resulting mechanical properties can be substantially the same, with normal production tolerances. In an example, each portion can have an average magnitude of mechanical properties (such as hardness, yield strength, or ultimate tensile strength), and a local magnitude within ±15% deviation from the average magnitude.

[0032] In an example, the main soft zone of the structural member is formed by subjecting the main soft zone to a different temperature treatment than other zones of the main member.

[0033] In some examples, the main soft zone of the structural member can further include a third portion having substantially constant third mechanical properties. The third mechanical properties can be higher than the second mechanical properties. Additionally, the main soft zone can include more than three portions arranged adjacent to each other.

[0034] In an example, the portions of the main soft zone can be arranged along the longitudinal direction based on their mechanical properties, that is, the portions having lower mechanical properties can be positioned closest to the load receiving end, and the portions having higher mechanical properties can be positioned further away from the load receiving end. This can result in a structural member that can effectively absorb energy during a collision, while controlling the kinematics of deformation and preserving the interior space of the vehicle. When the structural member is subjected to a compressive load, the first portion having lower mechanical properties than the second portion can deform first, before the second portion and before the rest of the main member.

[0035] In other examples, the portions of the main soft zone can be arranged along the longitudinal direction, where the portions having higher mechanical properties are located at positions closest to the load receiving end, and the portions having lower mechanical properties are located further away from the load receiving end. Further, the portions of the main soft zone can be arranged along the longitudinal direction based on other parameters or considerations.

[0036] In an example, the main soft zone can be configured to extend across the entire width (or entire cross-section) of the main member of the structural member. In other examples, the main soft zone can not cover the entire width of the main member. For example, in the case of a U-shaped cross-section, the main soft zone can extend from one side flange to the opposite side flange, or can cover only the side walls and the bottom, or only a part of the side walls and the bottom of the U-shape.

[0037] In an example, the structural member can include a secondary soft zone spaced apart from the main soft zone along the longitudinal direction. The secondary soft zone can be different from the main soft zone. For example, the secondary soft zone can include more or fewer portions having different mechanical properties than the main soft zone, and the arrangement of the portions within the secondary soft zone can be based on other parameters or considerations.

[0038] In some examples, the main member of the structural member outside the soft zone has an ultimate tensile strength of mainly 1000 MPa or more, specifically 1200 MPa or more, and more specifically 1500 MPa or more.

[0039] In an example, the main member defines a substantially U-shaped cross-section, and the substantially U-shaped cross-section includes a bottom wall, a first side wall, and a second side wall. Additionally, the main member may include a flange extending outward from the side wall.

[0040] In some examples, between the parts of the soft zone, that is, between the first part and the second part of the main soft zone or in the transition zone between the main member and the soft zone, the width may be less than 30 mm, specifically between 20 mm and 5 mm. The width of the transition zone may depend on manufacturing parameters, such as the temperature difference between adjacent parts, or on the manufacturing process.

[0041] Furthermore, in an example, the difference in the average yield strength between two adjacent parts may be greater than 10%, specifically greater than 15%, and possibly greater than 20%.

[0042] In some examples, the main member may include a region made of hardened, especially press-hardened steel. The main member may include a region made of ultra-high-strength steel (UHSS) having an ultimate tensile strength of 1000 MPa, especially 1500 MPa or greater.

[0043] In addition, the energy absorption along the length of the main member can be customized in different ways. For example, when the area of the cross-section of the main member increases, more energy can be absorbed. Therefore, the energy absorption can increase from the first cross-section of the main member closer to the position where the impact can be received to a farther cross-section.

[0044] In some examples, the main member may include one or more ribs. The ribs may extend throughout the bottom wall, or one of the first side wall and the second side wall.

[0045] Throughout this disclosure, a rib can be understood as an elongated, substantially straight part of the main member for local strengthening. The ribs can be manufactured during the stamping process. In some examples, the ribs can be formed by using a patchwork blank, that is, before the stamping process, the patchwork blank is welded (e.g., spot welded) to the main blank. In other examples, the ribs can be formed as a deformation of the same main blank.

[0046] The presence of one or more ribs in the main member can contribute to adjusting the deformation behavior of the structural member. The ribs, which are less ductile and more resistant compared to the main member, can help create specific bending positions in the structural member. Therefore, the deformation of the structural member can be optimized. In particular, when the structural member is configured to support compressive loads, the energy absorption can be increased.

[0047] The number, position, and extent of the portions having different mechanical properties from the remainder of the main member, as well as the number, position, and extent of the ribs in the structural member, can be selected based on the desired behavior of the structural member in terms of deformation, e.g., especially under compressive loads of the main member caused by (simulated) impacts or collisions.

[0048] In an example, the structural member can include an attachment to the main member. The attachment can be, for example, a plate or a cover attached at a flange of the main member. The attachment can also have a similar size and shape as the main member, i.e., the structural member is formed by two similar parts. In an example, both the main member and the attachment can have a U-shaped cross-section or a hat-shaped cross-section with flanges extending outward. In an example, the flanges can also be configured to have lower mechanical properties. The first part and subsequent parts of the soft zone can extend into the flanges, or the flanges can form yet another different part of the soft zone, i.e., the flanges can be subjected to a different heat treatment from the sidewalls and bottom of the U-shaped cross-section. The flanges can, for example, have a lower strength and greater ductility than the adjacent main soft zone.

[0049] In some examples, the soft zone including the aforementioned first part and second (and optionally additional) parts can also be formed in the attachment.

[0050] In another aspect, a method for manufacturing a structural member (the structural member being at least partially configured to support compressive loads) is provided to obtain a structural member for a vehicle frame as described in the present disclosure.

[0051] The method includes providing a main blank. The method further includes heating the main blank at least partially to a temperature above the austenitizing temperature, wherein adjacent first and second parts are heated in a different manner from other parts of the main blank, and press-hardening the heated main blank to form the main member of the structural member. The formed main member includes a main soft zone having lower mechanical properties than other zones of the main member. Further, the main soft zone includes a first part having substantially constant first mechanical properties and a second part having substantially constant second mechanical properties. Additionally, the first mechanical properties are lower than the second mechanical properties.

[0052] This method can improve the deformation behavior of a structural member configured to support compressive loads and can enable adjustment of how the structural member deforms during, for example, an automotive collision. Thus, the energy absorption of the structural member can be enhanced.

[0053] The main blank should be understood herein as a blank, e.g., a thin metal sheet or a flat metal plate that will form the main member. The main blank can be made of a hardenable steel, especially boron steel. The thickness of the main blank can typically be between 1 mm and 2.5 mm.

[0054] In an example of the method, the first part may be arranged closer to the load receiving end than the second part.

[0055] In some examples of the method, the heating step includes heating the preform substantially uniformly to a temperature above the austenitizing temperature and subsequently cooling a portion of the preform, in particular to a temperature below the austenitizing temperature.

[0056] In some examples of the method, the cooling may include blowing air against the portion of the preform to be cooled through a nozzle. The portion to be cooled may extend along a substantially transverse direction and / or along a substantially longitudinal direction of the preform.

[0057] This way of cooling a specific portion of the preform may create precisely defined temperature zones and temperature gradients along and / or across the preform. Thus, the cooling effect can be localized, and the mechanical properties of different parts can be precisely controlled. This allows for predictable and substantially constant mechanical properties within each part and a relatively small transition zone between them.

[0058] In some further examples, the cooling may include reducing the temperature of the cooled portion by 100 degrees relative to other parts of the main member, and more specifically by 200 degrees relative to other parts of the main member.

[0059] In some examples, a nozzle array or nozzle matrix may be used to perform the cooling. Thus, the nozzles can precisely define the portion of the main member to be cooled.

[0060] In an example, the nozzles may propel compressed air with an overpressure of at least 2 bar, specifically 3 bar and more specifically 4 bar. The overpressure should be understood as the pressure difference between atmospheric pressure under normal conditions and the total pressure of the compressed air (i.e., static pressure plus dynamic pressure).

[0061] In some examples, the nozzles may include at least one tangential nozzle. The tangential nozzle may propel compressed air with a direction component substantially parallel to the processing plane (i.e., the surface of the part). Thus, this tangential nozzle can create a flow seal, which can prevent air from other nozzles from reaching a portion of the preform. Therefore, the tangential nozzle can be used to control the temperature gradient along and / or across the preform.

[0062] In an example, the nozzles may include nozzles configured to create a negative pressure zone at a desired position inside the heating facility. The negative pressure zone may be suitable for separating regions with different air temperatures. Description of the Drawings

[0063] Non-limiting examples of the present disclosure will be described below with reference to the drawings, where:

[0064] Figure 1An example of a structural component for a vehicle that is at least partially configured to support a compressive load is schematically shown.

[0065] Figure 2 Two cross-sections of an example of the structural component are schematically shown.

[0066] Figure 3 Another example of a structural component for a vehicle that is at least partially configured to support a compressive load is schematically shown.

[0067] Figure 4 The variation of the yield strength of an exemplary main member with the longitudinal position after quenching is schematically shown.

[0068] Figure 5 Yet another example of a structural component for a vehicle that is at least partially configured to support a compressive load is schematically shown.

[0069] Figure 6 Schematically shown is Figure 5 a cross-section of the structural component.

[0070] Figure 7 Yet another example of a structural component for a vehicle that is at least partially configured to support a compressive load is schematically shown.

[0071] Figure 8 Another example of a structural component for a vehicle that is at least partially configured to support a compressive load is schematically shown.

[0072] Figure 9 Yet another example of a structural component for a vehicle that is at least partially configured to support a compressive load is schematically shown.

[0073] Figure 10 is a flowchart of a method for manufacturing a structural component that is at least partially configured to support a compressive load.

[0074] The accompanying drawings relate to exemplary embodiments and are only for assisting in understanding the claimed subject matter and are not limiting in any sense. Detailed Description

[0075] Figure 1Schematically shown is a structural component 100 for a vehicle configured or at least partially configured to support a compressive load. The structural component 100 includes a main member 110 that extends from a load receiving end 111 to an opposite end 112 along a longitudinal direction of the main member 110. The main member 110 includes a main soft zone 170 having lower mechanical properties than other zones of the main member. Further, the main soft zone 170 includes a first part 120 having substantially constant first mechanical properties and a second part 130 having substantially constant second mechanical properties. Further, the first mechanical properties are lower than the second mechanical properties.

[0076] In Figure 1 the example shown, the first part 120 is arranged closer to the load receiving end 111 than the second part 130, but in other examples, the second part 130 may be arranged closer to the load receiving end 111 than the first part 120.

[0077] As Figure 1 shown, the main soft zone 170 of the main member 110 may further include a third part 140 having substantially constant third mechanical properties. The third part 140 may be arranged adjacent to the second part 130. Further, the third mechanical properties may be higher than the second mechanical properties.

[0078] Thus, the main member 110 may include a main soft zone 170 that includes two or more parts 120, 130, 140 that are different in mechanical properties and are adjacent to one another. The parts 120, 130, 140 may be arranged based on mechanical properties, i.e., the part with the lowest mechanical properties is closest to the load receiving end 111. One aspect of this arrangement is that in the case of a compressive load (in the case of an impact), subsequent parts of the load receiving end have increased strength and will deform in a controlled manner, i.e., first the part closest to the load receiving end and having the lowest mechanical properties, then the adjacent subsequent parts having higher mechanical properties, and so on.

[0079] Alternatively, the parts 120, 130, 140 may be arranged based on other parameters or considerations. Thus, the arrangement of the parts 120, 130, 140 may be customized to regulate the behavior of the structural component 100 when subjected to a compressive load.

[0080] Figure 1 For the main member 110 of the structural component 100 in the example of, outside the main soft zone 170, it may have an ultimate tensile strength of mainly 1000 MPa or greater, specifically 1200 MPa or greater, and more specifically 1500 MPa or greater.

[0081] The soft zones in the examples can have a yield strength between 300 MPa and 950 MPa. For example, the soft zone can have a first part with a yield strength between 300 MPa and 500 MPa (e.g., an average of about 400 MPa), a second part with a yield strength between 400 MPa and 550 MPa (e.g., an average of about 475 MPa), a third part with a yield strength between 650 MPa and 800 MPa (an average of about 725 MPa), and a fourth part with a yield strength between 750 MPa and 950 MPa (e.g., an average of about 850 MPa).

[0082] In addition, Figure 1 The structural component 100 of the example shown in FIG. shows that the main member 110 can generally define a U-shaped or "hat-shaped" cross-section, and the U-shaped or "hat-shaped" cross-section includes a bottom wall 113 and first and second side walls 114, 115. The bottom wall 113 can be generally perpendicular to the first and second side walls 114, 115. In another example, the bottom wall 113 can define an angle different from 90 degrees with respect to the first and second side walls 114, 115. The structural component 100 can define other cross-sectional geometries. For example, the structural component 100 can define an L-shaped cross-section, a W-shaped cross-section, or other cross-sections.

[0083] In addition, the radius of curvature between the bottom wall 113 and the first and second side walls 114, 115 can be adjusted according to the specifications of the structural component 100 (i.e., the mechanical properties of the materials used, the desired maximum local strength, etc.).

[0084] As Figure 1 shown, the structural component 110 can include first and second flanges 116, 117 extending outward from the first and second side walls 114, 115 respectively. The flanges 116, 117 provide convenient attachment points to connect the structural component 100 to other parts of the vehicle (e.g., other components of the vehicle's structural frame). As mentioned above, the radius of curvature between the first and second side walls 114, 115 and the flanges 116, 117 can also vary according to the specifications of the structural component 110.

[0085] In the illustrated example, the main soft zone extends throughout the entire width of the main member and at least a part of the length of the main member. That is, in the case of the U-shaped cross-section of this example, the main soft zone extends from one side flange to the other side flange. In other examples, the soft zone can extend from one side wall to the other side wall without extending into the flanges. In some cases, secondary soft zones can be created in the flanges, for example, by using local heat treatment for local softening. For example, the connection areas of the flanges can be softened, that is, their mechanical properties can be reduced. Such local softening can improve the kinematics in the case of impact and, in particular, delay or avoid the rupture of the joints at the flanges.

[0086] In some examples, the main member 110 may be made of boron steel such as and, for example 1500 (22MnB5 steel, with or without a protective coating), 2000 (37MnB5) or any martensitic steel or ultra-high-strength steel (UHSS). 22MnB5 can be commercially obtained from ArcelorMittal. CRL-340LA can be commercially obtained from SSAB.

[0087] 1500 is supplied in a ferritic-pearlite phase. It has a fine-grained structure distributed in a uniform pattern. Its mechanical properties are related to this structure. After heating, the hot stamping process, and subsequent quenching, a martensitic microstructure is produced. As a result, the tensile strength and yield strength increase significantly.

[0088] The composition of 1500 is summarized as follows by weight percentage (the rest being iron (Fe) and impurities):

[0089] Maximum carbon (C) content (%): 0.25

[0090] Maximum silicon (Si) content (%): 0.4

[0091] Maximum manganese (Mn) content (%): 1.4

[0092] Maximum phosphorus (P) content (%): 0.03

[0093] Maximum sulfur (S) content (%): 0.01

[0094] Aluminum (Al) content (%): 0.01 - 0.1

[0095] Maximum titanium (Ti) content (%): 0.05

[0096] Maximum niobium (Nb) content (%): 0.01

[0097] Maximum copper (Cu) content (%): 0.20

[0098] Maximum boron (B) content (%): 0.005

[0099] Maximum chromium (Cr) content (%): 0.35

[0100] 2000 is an example of another boron steel, 37MnB5, which has an even higher strength. After the hot stamping die quenching process, the yield strength of 2000 can be 1400 MPa or higher, and its ultimate tensile strength can be higher than 1800 MPa.

[0101] The composition of 2000 is summarized by weight percentage as follows (the balance being iron (Fe) and impurities):

[0102] Maximum carbon (C) content (%): 0.36

[0103] Maximum silicon (Si) content (%): 0.8

[0104] Maximum manganese (Mn) content (%): 0.8

[0105] Maximum phosphorus (P) content (%): 0.03

[0106] Maximum sulfur (S) content (%): 0.01

[0107] Aluminum (Al) content (%): 0.01 - 0.06

[0108] Maximum titanium (Ti) content (%): 0.07

[0109] Maximum niobium (Nb) content (%): 0.07

[0110] Maximum copper (Cu) content (%): 0.20

[0111] Maximum boron (B) content (%): 0.005

[0112] Maximum chromium (Cr) content (%): 0.50

[0113] Maximum molybdenum (Mb) content (%): 0.50

[0114] Boron steels, such as 22MnB5 or 37MnB5, etc., may be presented with an aluminum-silicon coating in order to avoid decarburization and scaling during the forming process.

[0115] Several 22MnB5 and other boron steels with similar chemical compositions are commercially available. However, the exact content of each component in the 22MnB5 steel may vary slightly depending on the manufacturer. Other ultra-high-strength steels include, for example, BTR 165 available from Benteler.

[0116] Figure 2 Two cross-sections schematically showing examples of structural components are shown. These cross-sections and other cross-sections may be part of the same structural component, i.e., the structural component may have a cross-section that varies along the longitudinal direction, or may be cross-sections corresponding to different structural components.

[0117] Although in Figure 2Although not shown in the examples, the bottom wall 113 can be curved or include recesses or protrusions along the bottom. This also applies to the side walls 114, 115, which do not necessarily have to be completely straight. The side walls 114, 115 can include straight portions with curved transition regions therebetween. Additionally, the side walls 114, 115 can be symmetric or asymmetric. For example, the height of the first side wall 114 can be different from the height of the second side wall 115. In some examples, the height along the longitudinal direction of the first side wall 114 and / or the second side wall 115 can also vary. In an example, the width of the bottom wall 113 can be different from the height of the first side wall 114 and / or the second side wall 115. Other examples can include any combination of the above examples.

[0118] The shape and size of the flanges 116, 117 can be designed to be placed on a particular vehicle component and can be used to couple the structural component to other components, such as other vehicle frame components.

[0119] Figure 3 Another example of a structural component 100 for a vehicle is schematically shown, where the structural component is configured or at least partially configured to support a compressive load. In this example, the main member 110 includes a main soft zone 170 that includes three portions 120, 130, 140 that have a lower yield strength and / or ultimate tensile strength than the remainder of the main member 110. The three portions 120, 130, 140 can be more ductile than the remaining stiffer portions of the main member. In particular, the three portions can have a higher elongation at break and / or an increased reduction of area prior to fracture.

[0120] In addition, the three portions 120, 130, 140 have different mechanical properties due to the different heat treatments they undergo. Other numbers of portions (e.g., four or more) and other relative sizes can be included in the structural component 100 according to the present disclosure.

[0121] In the example shown, the local yield strength of each of the portions 120, 130, 140 can be within ±15% deviation of the average yield strength of the corresponding portion. Additionally, in some examples, the yield strength of each of the portions 120, 130, 140 can vary by less than 10% within each portion, i.e., the magnitude of the yield strength at the load receiving end of the portion 120 can be substantially constant.

[0122] As Figure 3As shown, the main member 110 may include a transition region 150 between the soft region 170 and other regions of the main member. The width of the transition region 150 is less than 30 mm, specifically between 20 mm and 5 mm. The width of the transition region 150 may depend on manufacturing parameters, such as the temperature difference between adjacent parts, or on the process followed in manufacturing the structural member.

[0123] The transition region 150 between adjacent portions 120, 130, 140 of the soft region 170 may have the same width as previously discussed. Thus, the yield strength in the transition region 150 may change abruptly, i.e., from a relatively high yield strength at the end of the transition region 150 adjacent to the main member 110 to a relatively low yield strength at the end of the transition region 150 adjacent to the main soft region 170.

[0124] In the example shown, and as can be seen in Figure 4 the first portion 120 located closest to the load receiving end 111 of the main member 110 is the "softest" and most ductile portion. The ductility (e.g., measured as the elongation at break or the reduction of area at break under given test conditions) may be highest in this portion, while the yield strength and ultimate tensile strength are lower. Further, in some examples, all portions 120, 130, 140 of the main soft region 170 are arranged in ascending order of mechanical properties along the longitudinal direction, i.e., based on the yield strength of the material forming the portion from low to high. This has also been shown in Figure 4 as well.

[0125] The difference in average yield strength between two adjacent portions 120 and 130, 130 and 140 may be greater than 100 MPa, 150 MPa, or 200 MPa. In an example, the adjacent portions may have an average yield strength difference of 10%, specifically greater than 15%, and more specifically greater than 20%. In some examples, the difference in average yield strength between two adjacent portions may not be the same as the difference between two other adjacent portions. For example, the difference in average yield strength between portions 120, 130 may be 10%, while the difference in average yield strength between portions 130, 140 may be 15%.

[0126] As in the example of Figure 1 the main soft region 170 extends substantially throughout the entire cross-section or the entire width of the main member.

[0127] Figure 4 is shown Figure 3Simplified diagram of the variation of the average yield strength of each cross-section of the structural member with the longitudinal position. The horizontal axis represents the longitudinal position along the structural member 100 from the load receiving end 111 to the opposite end 112, i.e., the load receiving end 111 corresponds to the coordinate center. The vertical axis represents the average cross-section yield strength after the structural member has been quenched, i.e., at room temperature after press hardening.

[0128] Note that Figure 4 the reference numerals in Figure 3 are associated with the features in Figure 3 . Therefore, the area in the figure with a given reference numeral is not the feature itself, but points to the yield strength of the corresponding feature in

[0129] In the materials typically used in hot stamping the structural members of the present disclosure, the yield strength (or tensile strength) and ductility are inversely correlated, i.e., as the microstructure of the material changes and the yield strength increases, the ductility decreases, and vice versa.

[0130] Therefore, Figure 4 shows that the yield strength at the load receiving end 111 of the main member 110 is relatively high and almost constant. Then, before reaching the first part 120, the yield strength of the main member 110 decreases sharply (and thus the ductility increases) at the first transition zone 150. This change in mechanical properties occurs in a relatively short width, such as about 20 mm or 30 mm. After this first transition zone 150, the main member 110 includes a first part 120 with low strength and high ductility. The mechanical properties of this first part 120 do not change significantly along the longitudinal direction because the heat treatment is in principle uniform for the first part 120.

[0131] The local yield strength of the main member is relatively high at the second transition zone 150 after the first part 120. The second platform part after the second transition zone 150 corresponds to the second part 130; and the same situation occurs between the second part 130 and the third part 140 and between the third part 140 and the rest of the main member 110 (i.e., the opposite end 112). As can be seen from Figure 4 the yield strength gradients in different transition zones 150 can be different.

[0132] Note that Figure 4 does not include strength and longitudinal dimensions as it is only used as an example of the present disclosure. In addition, compared with the length of the part of the main soft zone, the width of some transition zones in the transition zones may seem relatively large, but this has been clearly used to illustrate the potential differences in yield strength gradients. The microstructure that can be obtained can be controlled by appropriate temperature treatment.

[0133] As described above, the portions 120, 130, 140 may be arranged along the longitudinal direction based on other parameters or considerations. Additionally, the portions 120, 130, 140 do not necessarily have to be located between regions with high mechanical properties, i.e., one portion may be located at one end of the structural member 100.

[0134] Figure 5 Another example of a structural member 100 for a vehicle is schematically shown, where the structural member is configured or at least partially configured to support a compressive load. In this example, the structural member 100 may be a front longitudinal beam or a rear longitudinal beam of the vehicle.

[0135] In this example, the main member 110 includes a main soft zone 170 having three portions 120, 130, 140 that have a lower yield strength and / or ultimate tensile strength than the rest of the main member 110. These three portions 120, 130, 140 may be more ductile than the remaining harder portions of the main member. In particular, these three portions 120, 130, 140 may have a higher elongation at break and / or an increased reduction of area before fracture. Note that Figure 5 the three portions 120, 130, 140 in have been schematically shown in dashed lines, and the transition regions between the portions are not shown.

[0136] Furthermore, as in the above example, these three portions 120, 130, 140 have different mechanical properties. Other numbers of portions (e.g., four or more) and other relative dimensions may be included in the structural member 100 according to the present disclosure.

[0137] In this example, the structural member includes an add-on 180 attached to the main member 110. The add-on 180 may have a similar size and shape to the main member 110, i.e., the structural member 100 may be formed by two similar members 110, 180. Additionally, the add-on 180 may also include portions having a lower yield strength at the same positions as the main member 110. More precisely, the main member 110 and the add-on 180 may have substantially the same mechanical properties along their lengths. That is, in this example, the structural member is substantially symmetric in terms of mechanical properties.

[0138] In addition, in Figure 5 the example shown, the main member 110 and the add-on 180 have a substantially L-shaped cross-section. Each L-shaped cross-section includes a lateral wall 160 and a horizontal wall 190. The horizontal wall 190 further includes a flange 165 extending outward.

[0139] As Figure 5As shown, the flange 165 can be configured to contact the side wall 160 of another piece, i.e., the flange 165 of the main member 110 can be configured to contact the side wall 160 of the attachment 180, and vice versa. The main member 110 and the attachment 180 can be joined at the flange. Thus, the main member 110 and the attachment 180 together define a substantially rectangular closed cross-section.

[0140] In addition, the flange 165 and the portion of the side wall 160 configured to contact the flange 165 can be made of a material having lower mechanical properties than the portions 120, 130, 140 of the main member 110 and the attachment 180. For example, the most ductile portion (e.g., portion 120) of the main member 110 and the attachment 180 can have an average yield strength of about 600 MPa or greater, and the corresponding portions of the flange 165 and the side wall 160 can have a yield strength of about 550 MPa or less. Providing a softer flange can increase the toughness of the connection (e.g., spot weld) between the main member 110 and the attachment 180 in the event of an impact. At the same time, this enhances the overall dynamic response of the component 100 and allows for better control of deformation.

[0141] Figure 6 is schematically shown Figure 5 of the cross-section of the structural component 100.

[0142] As previously described, the main member 110 and the attachment 180 can be attached at their flanges 165, thereby defining a substantially rectangular closed cross-section.

[0143] In some examples, the geometry of the components can be different, e.g., they can define a substantially square closed cross-section, the radii of curvature of the components can be different, etc.

[0144] In other examples, the main member 110 and the attachment 180 can not have the same geometry, e.g., the main member 110 can have a substantially U-shaped cross-section, and the attachment 180 can be a substantially flat plate with a closed U-shaped cross-section. Also in these cases, a specific heat treatment different from the other parts of the main soft zone can be provided for the flange.

[0145] Figure 7 Another example of a structural component 100 for a vehicle is schematically shown, wherein the structural component 100 is at least partially configured to support a compressive load. In this example, the structural component 100 is a front longitudinal beam, but other vehicle components such as door rings, rear longitudinal beams, rear frames, sills, one-piece floors, cross members, front upper longitudinal beams, and chassis extensions, etc. can also be illustrative for the present disclosure.

[0146] In Figure 7 it, a compressive impact can be received in the main member 110 on the right side. In this case,Figure 7 On the right side of which will be the load receiving end 111.

[0147] Due to the introduction of parts 120, 130, 140 having mechanical properties lower than the rest of the main member 110, i.e., lower tensile strength, the deformation of the main member 110 can start near the location where the impact occurs rather than in any other area. Note that for simplicity, Figure 3 and Figure 4 the transition zone 150 shown in Figure 7 is not shown in this

[0148] Changing the mechanical properties of the various parts can facilitate the control of the deformation of the main member 110, especially the location where the deformation starts. Thus, when the first part 120 with the lowest mechanical properties is located closest to the point receiving the compressive impact, the main member will start to deform from this area.

[0149] Although not shown in Figure 7 the structural member 100 may further include a secondary soft zone spaced apart from the main soft zone 170 along the longitudinal direction. For example, a secondary soft zone having mechanical properties higher than those of the main soft zone 170 may be located farther from the load receiving end 111 to facilitate a second deformation point.

[0150] In some examples, ribs may be included in the main member 110 to further enhance the strength difference between the various parts of the main member 110. In fact, the characteristics of the ribs (including their number, shape, size, location, and the extensions extending over the main member 110) can be customized to adjust the behavior of the structural member 100 when subjected to a compressive load. The ribs create harder and more rigid regions in the structural member 100. In this way, the behavior of the main member 110 and the structural member 100 can be better controlled during a collision.

[0151] Figure 8 Another example of a structural member 100 for a vehicle frame is schematically shown, where the structural member is at least partially configured to support a compressive load. In this example, the structural member 100 is the vehicle's floor panel. In this particular example, the floor panel is a one-piece floor panel formed by a single integral part that combines, for example, seat cross-members and channels. The one-piece floor panel can be formed in a single press hardening process.

[0152] In Figure 8 the vehicle travels from left to right. In the sense of the independent claims, the longitudinal direction of the floor panel is vertical in Figure 8 . The floor panel in this example has been designed and manufactured to have a softer area that is designed to absorb energy in the case of a lateral impact, i.e., absorb energy from the top or from the bottom in the example of Figure 8 .

[0153] The floor panel in this example includes a main soft zone 170 having two portions 120, 130 that have a lower yield strength and / or ultimate tensile strength than the remainder of the main member 110. In particular, as can be seen in the example of Figure 8 , the main member 110 includes a main soft zone 170 located at a first side of the main member 110 and a secondary soft zone 171 located at a second side of the main member 110.

[0154] Each of the two portions 120, 130 of the main soft zone 170 and the secondary soft zone 171 is configured to be more ductile than the remainder of the stiffer portions of the main member 110. In particular, the two portions 120, 130 may have a higher elongation at break and / or an increased reduction of area prior to fracture.

[0155] In the example of Figure 8 , the first portion 120 is arranged closer to the load receiving end of the main member 110 than the other portion 130 and may be the "softest" and most ductile portion.

[0156] The floor panel of the vehicle may receive a side impact at the load receiving end 111. Since the first portion 120 having the lowest mechanical properties is located closest to the position receiving the compressive impact, the main member 110 may start to deform in the first portion 120 of the main soft zone 170, and subsequent portions of the load receiving end having increased strength will deform in a controlled manner. The floor panel can effectively absorb impact energy while controlling the kinematics of the deformation and preserving the interior space of the vehicle.

[0157] In the example of Figure 8 , the main soft zone tapers along the longitudinal direction (the direction in which compressive loads are received in the case of a side impact). The main soft zone decreases its width along the longitudinal direction. Thereby, a balance between high strength (low weight) and energy absorption can be provided. Even if the side impact is received more towards the front of the vehicle or more towards the rear of the vehicle, this arrangement can be utilized to deflect the deformation towards a more central region of the floor panel.

[0158] Figure 9 Another example of a structural component 100 for a vehicle frame is schematically shown, wherein the structural component is at least partially configured to support compressive loads. In this example, the structural component 100 is a door ring of the vehicle.

[0159] As Figure 9 shown, the door ring in this example extends from the A-pillar and the hinge pillar to the B-pillar. Thus, the door ring is a front door ring. In other examples, the door ring may be a complete door ring extending from the A-pillar to the C-pillar.

[0160] The front door ring in this example includes a B-pillar portion, a sill portion, a hinge portion, and an A-pillar portion. The door ring can be formed by joining different blanks, forming a composite blank, and then forming the composite blank into a single-piece integrated door ring.

[0161] In this example, the sill portion of the vehicle extending from the load receiving end 111 to the opposite end 112 along the longitudinal direction includes a soft zone 170.

[0162] Furthermore, the door ring, and more specifically, the sill portion of the door ring, includes a main soft zone 170 having four parts 120, 130, 140, 150, which have a lower yield strength and / or ultimate tensile strength than the rest of the main member 110.

[0163] These four parts 120, 130, 140, 150 can be more ductile than the remaining stiffer parts of the main member 110. In particular, these four parts 120, 130, 140, 150 can have a higher elongation at break and / or an increased reduction of area before fracture.

[0164] In Figure 9 the example, the four parts 120, 130, 140, 150 of the main soft zone 170 are arranged along the longitudinal direction of the sill portion of the floor panel. The first part 120 arranged closer to the load receiving end of the main member 110 than the other parts is the "softest" and most ductile part. The second part 130 is adjacent to the first part 120, the third part 140 is adjacent to the second part 130 and includes a third mechanical property that is higher than the mechanical properties of the first part 120 and the second part 130 but lower than the mechanical property of the fourth part 150, and the fourth part 150 is arranged adjacent to the third part 140.

[0165] In some examples, the yield strength of the first part 120 can be between 300 MPa and 600 MPa, specifically between 300 MPa and 500 MPa, and the yield strength of the second part 130 can be between 350 MPa and 600 MPa, specifically between 400 MPa and 550 MPa. Further, the yield strength of the third part 140 can be between 600 MPa and 850 MPa, specifically between 650 MPa and 800 MPa, and the yield strength of the fourth part 150 can be between 700 MPa and 1000 MPa, specifically between 750 MPa and 950 MPa.

[0166] The door ring of a vehicle can receive a frontal impact at the load receiving end 111. Since the first part 120 with the lowest mechanical properties is located closest to the position receiving the compressive impact, the main member 110 can start to deform in the first part 120 of the main soft zone 170, and the subsequent parts of the load receiving end with increased strength will deform in a controlled manner. The door ring can effectively absorb the impact energy while controlling the kinematics of the deformation and preserving the interior space of the vehicle.

[0167] In another aspect of the present invention, there is provided a method 200 for manufacturing a structural component 100 that is at least partially configured to support a compressive load, as described throughout this disclosure. The method 200 is schematically illustrated in the block diagram of Figure 10 .

[0168] The method 200 includes, at block 201, providing a main blank. The method further includes, at block 202, heating the main blank at least partially to a temperature above the austenitizing temperature, wherein the adjacent first part 120 and second part 130 are heated in a different manner from the other parts of the main blank.

[0169] Furthermore, the method 200 includes, at block 203, press hardening the heated main blank to form the main member of the structural component 100. The formed main member 110 includes a main soft zone 170 that has lower mechanical properties than the other zones of the main member 110. Further, the main soft zone 170 includes a first part 120 having substantially constant first mechanical properties and a second part 130 having substantially constant second mechanical properties. The first mechanical properties are lower than the second mechanical properties.

[0170] Further, the first part 120 can be arranged closer to the load receiving end 111 than the second part 130.

[0171] In an example where the main blank forms a main member 110 configured to be coupled to an additional component 180, the method 200 can include heating the part of the main blank intended to contact the additional component 180 (before deformation, during deformation, or after deformation) in a different manner from the other parts of the main blank, such that the mechanical properties of this part after forming are lower than the rest of the main member 110.

[0172] Additionally, the method 200 can be adapted to form a main member 110 having any combination of the previously discussed technical features.

[0173] The main blank can be made of any type of hardenable steel, as previously discussed for the structural component 100.

[0174] The heating step 202 of method 200 may include heating the main workpiece substantially uniformly to a temperature above the austenitizing temperature and then particularly cooling a portion of the main workpiece to a temperature below the austenitizing temperature.

[0175] In an example, before deforming the workpiece, the main workpiece may be heated to a temperature above Ac3, and a portion of the main workpiece may be cooled to a temperature below Ac3 and even below Ac1. Other portions may be maintained above Ac3 until the workpiece is deformed, or may be temporarily cooled and then reheated to a temperature above Ac3.

[0176] For example, during a first stage of the heating step 202, the main workpiece may be heated substantially uniformly in a main high-temperature furnace to a temperature above Ac3. Then, in a second stage of step 202, a portion of the main workpiece corresponding to the soft zone (after forming) may be cooled to a temperature below Ac3 while other portions are maintained at a higher temperature, such as above Ac3. Additionally, in a third stage of step 202, the main workpiece may be reheated so that the portion corresponding to the soft zone remains below Ac3 and the remaining portion of the main workpiece is maintained at a temperature above Ac3. In a case where the overall temperature of the main workpiece has decreased during the second stage, the third stage of step 202 may be used to raise the temperature of the remaining portion of the main workpiece to a temperature above Ac3. The three stages of step 202 may be carried out in the same high-temperature furnace or may be carried out in a separate facility downstream of the main high-temperature furnace.

[0177] In some examples, the heating step 202 of method 200 may include blowing air through nozzles against the portion of the main workpiece to be cooled. The nozzles may be distributed in an array or a 2D matrix to provide a more precise temperature distribution along and / or across the main workpiece. This may be carried out in the same high-temperature furnace in which the main workpiece is heated or may be carried out in a separate facility downstream of the main high-temperature furnace.

[0178] The inventors have found that this type of method of partially cooling a heated workpiece through pressurized nozzles allows cooling of a specific portion of the workpiece with a relatively small impact on the temperature of the remaining portion of the workpiece. This type of method allows precise control of the temperature distribution of the heated main member and the resulting material microstructure along the structural component. Further, this method represents a cost-effective way of forming the structural components of the present disclosure.

[0179] The cooling nozzles may set a temperature difference of at least 100 degrees, preferably at least 200 degrees, between at least a first portion 120 of the main member and the remaining portion of the main member 110. Further, a number of temperature differences between portions of the main member may be set. For example, three or more portions 120, 130, 140 may be provided in the main member 110, each having a different temperature.

[0180] In one example, a portion of the blank to be fully hardened can be maintained at a temperature of 900 °C or higher. The first portion can be reduced to a temperature below Acl, for example, between 600 °C and 700 °C. The second portion 120 can have a higher temperature than the first portion, but lower than the portion of the blank to be fully hardened. The temperature of the second portion can be, for example, between 700 °C and 800 °C.

[0181] Thus, different temperatures can result in different microstructures or strength properties being set in the corresponding portions of the main member 110, particularly during any subsequent rapid cooling (“quenching”), such as during a hot stamping process.

[0182] In an example, the main member is formed during the press hardening step 203 to form a component and is simultaneously quenched to a temperature below 400 °C, or specifically below 300 °C.

[0183] In an example, the cooling nozzle can include at least one tangential nozzle. The tangential nozzle can propel compressed air with a direction component that is generally parallel to the processing plane (i.e., the surface of the component). The tangential nozzle propels the compressed air at an angle other than zero relative to the surface of the component. For example, the tangential nozzle can be oriented such that the air flow from the tangential nozzle and the normal vector of the component surface define an angle less than 30 degrees, and more specifically less than 15 degrees.

[0184] Thus, this tangential nozzle can create a flow seal, which can prevent air from other nozzles from reaching a given portion of the main blank. Therefore, the tangential nozzle can be used to control the temperature gradient along and / or across the main blank.

[0185] In some examples, the cooling nozzle can be mounted on a movable frame that is capable of displacing and rotating the individual nozzles relative to the main blank.

[0186] Although only a number of examples are disclosed herein, other alternatives, modifications, uses, and / or their equivalents are possible. Therefore, the scope of the present disclosure should not be limited by the specific examples, but should be determined only by a reasonable interpretation of the appended claims.

Claims

1. A structural component (100) for a vehicle frame, the structural component being at least partially configured to support a compressive load, and comprising: A main member (110) extending from a load receiving end (111) to an opposite end (112) along a longitudinal direction of the main member (110), wherein, The main member (110) includes a main soft zone having lower mechanical properties than other zones of the main member, wherein, The main soft zone includes a first portion (120) having substantially constant first mechanical properties and a second portion (130) having substantially constant second mechanical properties, and wherein the first mechanical properties are lower than the second mechanical properties, wherein, The mechanical properties are ultimate tensile strength and yield strength.

2. The structural component (100) according to claim 1, wherein, The first portion (120) is arranged closer to the load receiving end (111) than the second portion (130).

3. The structural component (100) according to claim 1 or 2, wherein, The main soft zone further includes a third portion (140) having substantially constant third mechanical properties higher than the second mechanical properties.

4. The structural component (100) according to any one of claims 1 to 3, wherein, The portions (120, 130, 140) of the main soft zone are arranged along the longitudinal direction based on their mechanical properties, with the portions having lower mechanical properties being closer to the load receiving end (111) and the portions having higher mechanical properties being farther from the load receiving end (111).

5. The structural component (100) according to any one of claims 1 to 4, wherein, The main soft zone is formed by subjecting the main soft zone to a temperature treatment different from that of other zones of the main member (110).

6. The structural component (100) according to any one of claims 1 to 5, further comprising a secondary soft zone spaced apart from the main soft zone along the longitudinal direction and closer to the opposite end (112) of the main member.

7. The structural component (100) according to claim 6, wherein, The secondary soft zone has higher mechanical properties than the main soft zone.

8. The structural component (100) according to any one of claims 1 to 7, wherein, The main member (110) mainly has an ultimate tensile strength of 1000 MPa or greater, specifically 1200 MPa or greater, and more specifically 1500 MPa or greater.

9. The structural component (100) according to any one of claims 1 to 8, further comprising an attachment (180) configured to be coupled to the main member (110) at flanges (165, 116, 117), and wherein, The flanges (165, 116, 117) have lower mechanical properties than the main soft zone.

10. The structural component (100) according to any one of claims 1 to 9, wherein, The local yield strength of each of the first part (120) and the second part (130) varies by less than 15% from the average yield strength of the first part (120) and the second part (130), respectively.

11. The structural component (100) according to any one of claims 1 to 10, wherein, the difference in average yield strength between two adjacent parts (120, 130) is greater than 10%, and specifically greater than 20%.

12. The structural component (100) according to any one of claims 1 to 11, wherein, the structural component (100) is any one of a door ring, a rear longitudinal beam, a rear frame, a sill, a floor panel component, a cross beam, a passenger seat part, and a chassis extension, or is formed as a part of any one of a door ring, a rear longitudinal beam, a rear frame, a sill, a floor panel component, a cross beam, a passenger seat part, and a chassis extension.

13. A method (200) for manufacturing a structural component (100) for a vehicle frame, the method (200) comprising: providing (201) a main blank; heating the main blank at least partially to a temperature above the austenitizing temperature, wherein adjacent first and second parts are heated in a different manner from other parts of the main blank; and press hardening (203) the heated main blank to form a main member of the structural component, the main member including a main soft zone having lower mechanical properties than other zones of the main member, wherein, the main soft zone includes the first part (120) having substantially constant first mechanical properties and the second part (130) having substantially constant second mechanical properties, and wherein the first mechanical properties are lower than the second mechanical properties, wherein, the mechanical properties are ultimate tensile strength and yield strength.

14. The method (200) according to claim 13, wherein, heating (202) the main blank includes heating the main blank substantially uniformly to a temperature above the austenitizing temperature and then cooling a part of the main blank, in particular cooling to a temperature below the austenitizing temperature.

15. The method (200) according to claim 14, wherein, cooling the part of the main blank includes blowing pressurized air against the part through a nozzle.

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