Single fire panel for vehicle

Description

SINGLE FIRE PANEL FOR VEHICLE

[0001] This application claims the benefit of European patent no. 23 382 332.7, filed on April 5, 2023.

[0002] This disclosure relates to fire-resistant panels for vehicles, and more particularly to unitary fire-resistant panels for vehicles and methods of manufacturing unitary fire-resistant panels for vehicles. CONTEXT

[0003] Vehicles such as cars incorporate a structural skeleton designed to withstand the loads to which the vehicle may be subjected during its service life. The structural skeleton is also designed to resist and absorb impacts, in the event of, for example, collisions with other cars or road structures.

[0004] The trend toward manufacturing low-emission and more efficient vehicles has increased dramatically in recent decades. The rapid development of hybrid and electric vehicles has forced the industry to design new car components, namely for weight reduction and therefore greater vehicle range, and to accommodate and protect new car components, among other things. Thus, the demand for weight reduction in the automotive industry has led to the development and implementation of lightweight materials or components, and related manufacturing processes and tooling. The demand for weight reduction is especially driven by the goal of reducing CO2 emissions. The growing concern for occupant safety also leads to the adoption of materials that improve vehicle integrity during a collision, while also improving energy absorption.

[0005] Press hardening, also known as Hot Forming Die Quenching (HFDQ), typically uses boron steel blanks to create stamped components with Ultra High Strength Steel (UHSS) properties, with tensile strengths of, for example, 1,500 MPa or 2,000 MPa or even more. The increased strength allows a thinner gauge material to be used, resulting in weight savings compared to conventionally cold-stamped mild steel components. Throughout this disclosure, UHSS may be considered a Petition 870250090735, dated 06 / 10 / 2025, page 6 / 91 2 / 20 steel with an ultimate tensile strength of 1,000 MPa or more, particularly after a press hardening process.

[0006] In an HFDQ process, a blank to be hot-formed can be heated to a predetermined temperature, for example, austenitizing temperature or higher (and particularly between Ac3 and an evaporation temperature of, for example, a coating on the blank). A furnace system can be used for this purpose. Depending on specific needs, a furnace system can be supplemented with additional heaters, for example, induction or infrared heaters. By heating the blank, the strength of the blank decreases and the deformability increases, i.e., to facilitate the hot stamping process.

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

[0008] Typical vehicle components that can be manufactured using the HFDQ process include: door bars, bumper bars, cross members / side members, A / B pillar reinforcements, front and rear rails, seat cross members, and roof rails.

[0009] To improve ductility and energy absorption in specific areas of a component, it is known to introduce softer regions within the same component. This improves ductility locally while maintaining the required high overall strength. By locally adapting the microstructure and mechanical properties of certain structural components so that they comprise regions with very high strength (very hard regions), i.e., regions with high ultimate tensile strength and high yield strength, and regions with greater ductility (softer regions), i.e., regions with lower ultimate tensile strength and lower yield strength and greater elongation before rupture, it may be possible to improve their overall energy absorption and maintain their structural integrity during a collision situation, and also reduce their total weight. Such soft zones may also advantageously, Petition 870250090735, dated 06 / 10 / 2025, page 7 / 91 3 / 20 alter the kinematic behavior in case of collapse of a component under impact.

[0010] Known methods for creating regions with increased ductility (soft zones) in structural vehicle components include providing tooling comprising a pair of complementary upper and lower die units, each unit having separate die elements (steel blocks). A blank to be hot-formed is preheated to a predetermined temperature, for example, austenitizing temperature or higher, by, for example, a furnace system, in order to reduce resistance, i.e., to facilitate the hot stamping process.

[0011] Die elements can be designed to work at different temperatures in order to have different cooling rates in different zones of the part being formed during the quenching process, and thus result in different material properties in the final product, for example, soft areas that will generally have lower ultimate tensile strength and lower yield strength, but allow more elongation before rupture. For example, a die element can be cooled to quench the corresponding area of ​​the component being manufactured at high cooling rates and thus reduce the component temperature rapidly and obtain a hard martensitic microstructure.Another neighboring die element may be heated to ensure that the corresponding portion of the component being manufactured cools at a lower cooling rate in order to obtain a softer microstructure, including, for example, bainite, ferrite, and / or pearlite. Such an area of ​​the component may remain at higher temperatures than the rest of the component when it exits the die.

[0012] Other methods for obtaining hot-stamped components with areas of different mechanical properties include, for example, adapted or differential heating before stamping, and local heat treatments after a stamping process to alter the local microstructure and obtain different mechanical properties. Other possibilities also include the use of raw patchwork pieces and Petition 870250090735, dated 06 / 10 / 2025, page 8 / 91 4 / 20 Adapted Welded (TWB) blanks combining different thicknesses and / or materials in blanks.

[0013] UHSS can exhibit tensile strengths as high as 1,500 MPa, or even 2,000 MPa or more, particularly after a press hardening operation. Once hardened, a UHSS can have a martensitic microstructure. This microstructure allows for greater maximum tensile strength and yield strength per unit weight.

[0014] In addition to the Ultra High Strength Steels mentioned earlier, more ductile steels can also be used in structural skeletal parts that require energy absorption. These steels can be used in hot stamping processes, but will not achieve a martensitic microstructure in the process. Ductibor® 1000 is an example of a suitable, more ductile steel.

[0015] Vehicles such as cars comprise a passenger compartment or cabin, which is the space adapted to accommodate the driver and other passengers, and an engine compartment, which houses the engine, among other things, and is located in front of the passenger compartment.

[0016] The passenger compartment is separated from the engine compartment by what is called a firewall. Firewalls are usually made of lightweight materials and isolate the cabin from engine noise and heat.

[0017] Firebreaks are commonly manufactured by welding together different parts that have been previously cold-stamped or otherwise formed. These parts usually have different thicknesses and are made of different materials, particularly those suitable for cold stamping.

[0018] Firewalls are generally not designed or configured to withstand and absorb impacts, for example, in the event of collisions with other cars, other vehicles or obstacles. Therefore, it is known to provide reinforcing members, which are commonly welded to the firewall so that, in the event of a collision, the firewall is provided with elements that distribute the impact forces to the structural skeleton of the vehicle, for example, rocker arms or hinge pillars. Petition 870250090735, dated 06 / 10 / 2025, page 9 / 91 5 / 20

[0019] Firestops are manufactured separately from reinforcements, which have different sizes and shapes depending on the specifications of the firestop in which they are being installed. These reinforcements comprise different thicknesses and different materials that allow the firestop to achieve the necessary rigidity. For example, such reinforcements can be made of press-hardened boron steel.

[0020] One problem that has been encountered is that manufacturing firewalls by welding stamped parts is a slow process that produces some weak points in the structure. Another issue to consider is that reinforcements welded to the firewalls to make them more resistant to impact loads can increase the vehicle's weight.

[0021] This disclosure provides examples of systems and methods that offer improvements over prior art firebreaks. SUMMARY

[0022] In a first aspect, a method for manufacturing a fire-resistant panel is provided. The method comprises providing a plurality of blanks, joining the blanks to form a combined blank, and hot stamping the combined blank to form the unitary fire-resistant panel.

[0023] Joining the blanks together to form a combined blank and then hot stamping the combined blank provides a lightweight and strong unitary fire-resistant panel, constructed in fewer steps, since post-forming welding operations are reduced. Avoiding or reducing post-forming welding operations also reduces the corresponding heat-affected zones. The unitary fire-resistant panel can have improved impact performance while maintaining a reduced weight.

[0024] Hot stamping is a process that allows for the appropriate deformation of, for example, ultra-high-strength steel to form the resulting complex structure of the unitary fire-resistant panel.

[0025] In some examples, raw pieces of different thicknesses and / or material grades can be used to meet specific requirements for strength and energy absorption and distribution and to optimize weight. Petition 870250090735, dated 06 / 10 / 2025, page 10 / 91 6 / 20

[0026] In some examples, joining the blanks involves forming one or more overlapping regions formed by the partial overlapping of the blanks with one another. In this disclosure, partially overlapping two blanks means that only a portion of the two blanks overlaps.

[0027] The overlapping region(s) may provide a firewall with thicker regions, which may distribute collision energy to the structural components of the vehicle's skeleton. A firewall that is no longer merely a physical separation between the engine compartment and the passenger cabin, but also has a structural function, may be provided. The unitary firewall may be more rigid and may be able to distribute collision energy, preferably without the need to weld additional reinforcements. Improved vehicle collision performance may therefore be achieved with fewer components.

[0028] In some examples, an overlapping region may be formed along a longitudinal direction of the unitary firewall. A longitudinal direction may be considered here as a direction that is substantially transverse to the longitudinal direction of the vehicles.In a frontal collision, overlapping regions can stiffen the firewall and distribute impact energy to the sides of the firewall and to the vehicle's structural elements. Reinforcement in a region vulnerable to impact loads can be provided, and the collision performance of the firewall can be improved.

[0029] In other examples, an overlap region may be formed along a vertical direction of the unitary firewall panel. A stiffer firewall panel may be provided, which may distribute the impact load to the vehicle's structural elements, for example, the rocker arms, the tunnel, or the hinge pillars. The overlap region may be located on one lateral side or on both lateral sides of the unitary firewall panel. An overlap along a vertical direction may also be located in a substantially central area and in the lower half of the firewall panel. Such an overlap may locally strengthen the firewall panel and conduct loads to, for example, the tunnel. Petition 870250090735, dated 06 / 10 / 2025, page 11 / 91 7 / 20

[0030] In some examples, the deformation of the combined raw part can be done in a single operation. Deforming the combined raw part in a single operation can result in improved manufacturing process efficiency for a vehicle firewall panel.

[0031] In examples, areas of greater thickness are provided in the combined bulk piece (either by overlapping region or, for example, by providing a patch bulk piece) in order to provide load paths to direct loads to, for example, a hinge pillar, a floor or a tunnel. Such areas of greater thickness may be arranged so that the areas of the firewall that are joined to other parts of the vehicle structure have greater strength and stiffness. Such areas of greater thickness may extend, for example, from a central area of ​​the firewall (central in a horizontal and / or vertical direction) towards the areas where the firewall is joined to other components of a vehicle structural frame, particularly rocker arms, floor, tunnel, hinge pillar or A-pillar.

[0032] In a further aspect, a unitary fire-resistant panel, as obtained by a method according to any of the examples described herein, is provided. BRIEF DESCRIPTION OF THE DRAWINGS

[0033] Non-limiting examples of the present disclosure will be described below, with reference to the accompanying figures, in which: Figure 1 shows an example of a vehicle firewall according to the prior art; Figure 2a shows an example of a plurality of unfinished pieces before they are joined together to form a combined unfinished piece; Figure 2b shows an example of a combined raw piece formed by two raw pieces joined together; Figure 3a shows another example of a plurality of unfinished pieces before they are joined to form a combined unfinished piece; Figure 3b shows an example of a combined raw piece formed by joining the raw pieces from Figure 3a; Petition 870250090735, dated 06 / 10 / 2025, page 12 / 91 8 / 20 Figure 4 shows an example of a combined raw piece comprising a patch raw piece; Figure 5 shows another example of a combined raw piece comprising patchwork raw pieces; Figure 6 shows an example of a unitary fire-resistant panel of a vehicle according to the present disclosure; and Figure 7 is a flowchart of a method for manufacturing a single fire-resistant panel for a vehicle.

[0034] The figures refer to example implementations and may be used only as an aid to understanding the subject matter claimed, not to limit it in any way. DETAILED DESCRIPTION OF THE EXAMPLES

[0035] In these figures, the same reference signs were used to designate corresponding elements.

[0036] Figure 1 schematically represents a prior art firewall. The firewall is made of a plurality of independent cold-formed components 1 that are subsequently welded together. The plurality of cold-formed components may comprise different shapes and different thicknesses. The firewall is a mere physical separation between the engine compartment and the passenger cabin of a vehicle and is not configured to withstand and absorb impacts, in the event of, for example, collisions with other cars.

[0037] In addition, the firewall comprises a plurality of transverse members 2 or reinforcing members that extend along a longitudinal direction of the firewall. These transverse members 2 are welded to the firewall and act as reinforcements in collision events.

[0038] In one aspect of the disclosure, a unitary fireproof panel 100 is provided. The unitary fireproof panel 100 is made from a plurality of blanks joined together to form a combined blank. The unitary fireproof panel is obtained after hot stamping of the combined blank. A unitary fireproof panel with improved collision performance can therefore be obtained. Petition 870250090735, dated 06 / 10 / 2025, page 13 / 91 9 / 20

[0039] As schematically illustrated in Figure 2a, a unitary fire-resistant panel 100 can be manufactured by joining a first blank piece 10 and a second blank piece 20 to form a combined blank piece 30. In the example in Figure 2a, the first blank piece 10 can define the upper part of the fire-resistant panel, while the second blank piece 20 can define the lower part of the fire-resistant panel. In other examples, the unitary fire-resistant panel 100 can be manufactured by joining blank pieces that define other parts of the fire-resistant panel or by joining more than two blank pieces.

[0040] The blanks can have a thickness between 0.5 and 5 mm, preferably 0.8 and 3 mm. In some examples, the thickness of the various blanks may be substantially the same. In other examples, depending on the position of the blank in the fire-resistant panel, different thicknesses of the blanks may be desired, and blanks with different thicknesses may be joined to form the combined blank. Furthermore, the plurality of blanks 10, 20 that form the combined blank 30 may be made of different materials. In some examples, the blanks 10, 20 may be made of ultra-high-strength steels (UHSS), for example, Usibor® or Ductibor®. In other examples, aluminum blanks, for example, aluminum from the 6000 or 7000 series, may be used.

[0041] A combined blank piece 30, including the two blank pieces 10, 20, can thus be formed as shown in Figure 2b, by joining a first blank piece 10 and a second blank piece 20. The joining of the blank pieces may comprise the formation of one or more overlapping regions formed by the partial overlapping of the blank pieces with one another, i.e., one blank piece may be positioned only partially over the other blank piece and the blank pieces are then joined together. The overlapping region may have a width of at least 5 cm in some examples. An overlapping region thus acquires an increased thickness compared to the rest of the blank pieces. Such an increase in thickness can be used to adapt the mechanical properties as needed and to provide local strength and / or stiffness in the unitary fire-resistant panel in areas where, in the prior art, reinforcement is required.

[0042] In addition, overlapping regions can be used to disperse impact energy to other parts of the vehicle. Overlapping regions can Petition 870250090735, dated 06 / 10 / 2025, page 14 / 91 10 / 20 understand load paths that can transfer impact energy to other vehicle elements configured to absorb such energy. In the case of, for example, a frontal impact, the impact load can be transmitted through the firewall to structural elements of the vehicle that are designed to absorb the energy produced in the collision. Additional structural reinforcements in the firewall panel can thus be avoided and the collision performance of the firewall can be improved while reducing the number of components.

[0043] The joining of the raw parts can be done by any of the following methods: laser welding, spot welding or arc welding.

[0044] Returning to figure 2b, an overlapping region 40 can be formed along a longitudinal direction of the unitary firewall by joining the first and second blank pieces 10, 20 of figure 2a. The overlapping region 40 can form a horizontal band in the lower half of the firewall, i.e., the overlapping region 40 can be a substantially straight region that is vertically offset from the center towards the bottom of the combined blank piece 30. The overlapping region 40 can extend from a first end to a second end of the combined blank piece 30, i.e., for the entire length of the firewall (or for substantially the entire width of the vehicle). Furthermore, both ends of the overlapping region can be vertically aligned.

[0045] In a frontal collision, overlapping regions along a longitudinal direction can stiffen the firewall and distribute impact energy to the vehicle's structural elements. Additional structural reinforcements in the firewall may therefore be unnecessary. A unitary firewall can thus be obtained, comprising a reinforcement along a longitudinal direction which, in the event of a frontal impact, for example with another car, can disperse the collision loads. Therefore, a unitary firewall manufactured with few parts and capable of distributing collision energy can be provided.

[0046] In some examples, the overlapping region may have a length L1 corresponding to a unit fire-resistant panel length of 100. In the example in Figure 2b, the overlapping region may have a length L1 corresponding to a Petition 870250090735, dated 06 / 10 / 2025, page 15 / 91 The 11 / 20 length of the unitary fire-resistant panel may have a width W1 of at least 1 cm, for example, between 1 and 5 cm. In some examples, the width of the overlap region may be at least 5 cm. In some examples, the width of the overlap region may not be constant, for example, the overlap region may be wider towards a central portion of the combined bulk piece 30. Suitable dimensions for the overlap region 40 may be chosen taking into account weldability, strength, stiffness and energy distribution requirements. A larger overlap region 40 means an increase in thickness over a larger area and therefore an increase in strength and stiffness locally in the unitary fire-resistant panel 100, as well as better energy distribution.

[0047] In a subsequent step, the combined blank 30 is hot-stamped and the unitary fire-resistant panel is formed. In particular, the combined blank can be heated above an austenitizing temperature, for example, around 900-920 °C in a furnace. And, subsequently, the combined blank can be deformed and hardened in a pressing apparatus. In particular, rapid cooling above a critical cooling rate of the combined blank can achieve a martensitic microstructure and high ultimate tensile strength and high yield strength.

[0048] In some examples, the partial overlapping of the raw pieces with each other may comprise the formation of an overlapping region in a substantially vertical direction of the unitary fire-resistant panel 100.

[0049] Figure 3a shows another example of joining a first blank piece 10 and a second blank piece 20 to form a combined blank piece 30. As shown, the blank pieces in Figure 3a have different shapes from the shapes of the blank pieces in the example in Figure 2a and therefore an overlapping region 40 different from that in Figure 2b will be obtained by partially overlapping the blank pieces 10, 20 on each other.

[0050] In the example in Figure 3b, a substantially U-shaped overlapping region can be formed by the partial overlapping of the raw pieces 10, 20 with each other. In addition to the overlapping region 40 also formed in Figure 2b, one or more Petition 870250090735, dated 06 / 10 / 2025, page 16 / 91 12 / 20 overlapping regions 50, 60 can be formed along a vertical direction of the unitary fire-resistant panel such that an overlapping region can be located on a first lateral side of the unitary fire-resistant panel 100. Figure 3b shows a first lateral side of the combined blank 30 comprising a first vertical overlapping region 50 and a second lateral side of the combined blank 30 comprising a second vertical overlapping region 60. In some examples, the vertical overlapping regions may have a width of at least 1 cm, preferably at least 5 cm. The overlapping regions located on a lateral side of the unitary fire-resistant panel can provide additional thickness in said region and can provide a unitary fire-resistant panel that can disperse the load from a frontal impact to, for example, the rocker arms and / or hinge pillars of the vehicle.

[0051] Furthermore, the size and shape of the blanks may depend on where a 40, 50, 60 overlap region may be desired in the blank. In other examples, a first blank that may define the left side of the firewall may be joined to a second blank that may define the right side of the firewall, forming a substantially vertical overlap region in the center of the firewall. This may lead to a unitary firewall that may have greater stiffness in a central part and along a substantially vertical direction and that may be able to distribute impact loads to structural elements of the vehicle body, for example, the tunnel.

[0052] As schematically illustrated in Figure 4, in some examples, a patch 70 blank can be joined to at least one of the blanks of the plurality that forms the combined blank 30. The patch 70 blank can be added substantially to a central portion of one of the blanks. A patch 70 blank can be added as reinforcement to increase strength and distribute the impact load from a specific area of ​​the combined blank 30 to structural parts of the vehicle configured to absorb impact energy, such as the floor tunnel and rocker arms. Petition 870250090735, dated 06 / 10 / 2025, p. 17 / 91 13 / 20

[0053] In this particular example, a 70 patch blank has been added to the central portion of the 20 blank, in a substantially central lower part of the combined blank 30, so that the load energy can be transmitted to the vehicle tunnel. In other examples, a 70 patch blank may be arranged along a vertical direction of the combined blank 30, optionally on a first lateral side of the combined blank. The impact load can therefore be distributed to the vehicle hinge pillars and / or to the rocker arms.

[0054] Patch 70 blanks can be joined to blanks by overlapping one blank with the other blank and using spot welding. In other examples, alternative welding techniques can be used, for example, laser welding or arc welding.

[0055] Figure 5 schematically represents another example of a combined bulk piece 30 comprising four bulk patch pieces. As shown in Figure 6, a first bulk patch piece 71 can be joined to a lower central portion of a bulk piece, which, in case of impact, can direct the impact load to the vehicle floor tunnel. A second and a third bulk patch piece 72, 73 can be joined to an upper portion of the combined bulk piece, i.e., to an upper half of the panel. The second and third bulk patch pieces are shown positioned offset from a vertical centerline of the panel.

[0056] In addition, the blank 10 of figure 6 may also comprise a fourth patch blank 74 which may extend longitudinally from one side to the other of the combined blank and which may be located between the first 71 and the second and third patch blanks 72, 73. In other examples, the combined blank may comprise additional patch blanks or fewer patch blanks, depending on where greater strength and / or impact load distribution may be desired in the unitary fire-resistant panel.

[0057] In other examples, the blank pieces 10, 20 joined to form the combined blank piece 30 may be formed by a plurality of blank pieces or sub-blank pieces, for example, of different thicknesses and / or different materials. In these examples, the plurality of blank pieces may be Adapted Welded Blank Pieces Petition 870250090735, dated 06 / 10 / 2025, page 18 / 91 14 / 20 (TWB). TWBs can be formed by joining the blank sub-pieces by edge-to-edge welding, where welding may include laser welding. In other examples, the plurality of blanks joined to form the combined blank can be joined by forming one or more overlapping regions formed by the partial overlapping of the blanks with each other. In these cases, any of laser welding, arc welding, or spot welding can be used.

[0058] In some examples, the plurality of blanks 10, 20 that form the combined blank 30 may be made of different materials. In some examples, the blanks 10, 20 may be made of ultra-high-strength steels (UHSS). Boron steel, for example, 22MnB5, or other steel compositions mentioned or referred to previously, may be suitable UHSS. These blanks, for example, boron steel blanks, may comprise an aluminum silicon coating or zinc coating.

[0059] Usibor® 1500P is an example of 22MnB5 steel. The composition of Usibor® is summarized below in weight percentages (the remainder is iron (Fe) and impurities): Carbon (C) maximum (%): 0.25 Silicon (Si) maximum (%): 0.4 Manganese (Mn) maximum (%): 1.4 Phosphorus (P) maximum (%): 0.03 Sulfur (S) maximum (%): 0.01 Aluminum (Al) (%): 0.01 - 0.1 Titanium (Ti) maximum (%): 0.05 Niobium (Nb) maximum (%): 0.01 Copper (Cu) maximum (%): 0.20 Boron (B) maximum (%): 0.005 Chromium (Cr) maximum (%): 0.35

[0060] Usibor® 1500P can have a yield strength of, for example, 1,100 MPa, and an ultimate tensile strength of 1,500 MPa.

[0061] Usibor® 2000 is another boron steel with even higher strength. The yield strength of Usibor® 2000 can be 1,400 MPa or more, and the tensile strength Petition 870250090735, dated 06 / 10 / 2025, p. 19 / 91 15 / 20 final strength can exceed 1,800 MPa. The composition of Usibor® 2000 is summarized below in weight percentages (the remainder is iron (Fe) and impurities): Maximum Carbon (C) (%): 0.36 Maximum Silicon (Si) (%): 0.8 Maximum Manganese (Mn) (%): 0.8 Maximum phosphorus (P) (%): 0.03 Maximum Sulfur (S) (%): 0.01 Aluminum (Al) (%): 0.01 - 0.06 Maximum Titanium (Ti) (%): 0.07 Maximum niobium (Nb) content (%): 0.07 Maximum Copper (Cu) (%): 0.20 Maximum Boron (B) (%): 0.005 Maximum Chromium (Cr) (%): 0.50 Maximum Molybdenum (Mb) (%): 0.50

[0062] The plurality of blanks that form the combined blank 30 may comprise different materials and / or thicknesses. For example, blanks made of Usibor® (e.g., Usibor® 1500 and / or Usibor® 2000) may be used in the blanks that form the combined blank 30. The use of these types of materials in hot forming and subsequent quenching processes leads to a predominantly martensitic structure due to Usibor®. One or more of the blanks may be made of a different and particularly more ductile material, for example, Ductibor® 1000.

[0063] Ductibor® 1000 is another material used in hot stamping to increase elongation compared to Usibor® 1500 and Usibor® 2000. The yield strength of Ductibor® 1000 can be 800 MPa or more, and the ultimate tensile strength 1000 MPa or more. The composition of Ductibor® 1000 is summarized below in weight percentages (the remainder is iron (Fe) and impurities): Maximum Carbon (C) (%): 0.10 Maximum Silicon (Si) (%): 0.6 Maximum Manganese (Mn) (%): 1.8 Petition 870250090735, dated 06 / 10 / 2025, p. 20 / 91 16 / 20 Maximum phosphorus (P) (%): 0.03 Maximum Sulfur (S) (%): 0.01 Aluminum (Al) (%): 0.01 - 0.1 Maximum Titanium (Ti) (%): 0.05 Maximum niobium (Nb) content (%): 0.10 Maximum Copper (Cu) (%): 0.20 Maximum Boron (B) (%): 0.005 Maximum Chromium (Cr) (%): 0.20

[0064] In other examples, the plurality of blanks 10, 20 that form the combined blank 30 can be made of aluminum. The aluminum of the plurality of blanks can be an aluminum alloy selected from the 6000 and 7000 series aluminum alloy groups. These series are characterized by their strength, corrosion resistance, and weldability.

[0065] In some examples, the unitary fire-resistant panel 100 may comprise areas with different ultimate tensile strengths according to any of the examples described herein.

[0066] In some of these examples, different materials may be used in the combined raw piece 30. In some of these examples, areas with different final tensile strengths may have a different microstructure.

[0067] Different microstructures can be created in a hot-formed firewall panel 100. These different microstructures can be created by heating a combined blank 30 above the austenitizing temperature and then controlling the cooling of the combined blank 30 during the forming of the combined blank 30 to form a unitary firewall panel 100 of a vehicle. The cooling of different areas of the combined blank 30 can be controlled by providing zones of the forming tool with heaters. Consequently, the unitary firewall panel 100 comprises zones with a predominantly martensitic structure and zones comprising ferrite, pearlite or bainite or a mixture thereof. Alternatively, a different microstructure can be created by partially heating, for example, using a laser beam, a portion of the panel. Petition 870250090735, dated 06 / 10 / 2025, page 21 / 91 17 / 20 unitary firestop that has been tempered by pressing to alter the predominantly martensitic structure to a structure containing ferrite and / or pearlite and / or bainite and / or tempered martensite and a mixture thereof. The tensile strength of the predominantly martensitic structure may be above 1400 MPa, and specifically above 1500 MPa.

[0068] The unitary fire-resistant panel 100 can thus be made of a material that can be effective in absorbing energy during an impact. In some examples, the plurality of raw pieces 10, 20 can be made of at least one ultra-high-strength steel.

[0069] The plurality of raw pieces can have an ultimate tensile strength of 1,000 - 2,000 MPa, specifically 1,500 - 2,000 MPa.

[0070] In some examples, the thickness of the plurality of raw pieces may be different, for example, the thickness of a first raw piece 10 may be different from the thickness of a second raw piece 20.

[0071] In some examples, joining the blanks to one another comprises welding the blanks to one another. In some examples, the blanks may be welded by spot welding and / or laser welding. Joining the blanks before deformation may make joining easier because the blanks are substantially flat at the time of joining. Welding blanks before the laser deformation and / or spot welding process can be efficient and precise.

[0072] In some examples, hot stamping or hot forming of the combined blank may comprise heating the combined blank 30 above the austenitizing temperature and then forming the combined blank 30 to create the unitary fire-resistant panel 100. In some examples, forming may comprise two or more forming steps.These forming steps may include, for example, molding, cutting or trimming and may be performed in a single multi-stage press. Examples of multi-stage presses are known, for example, from US 9,492,859 B2 and WO 2016142367 A1.

[0073] Deformation may include hot forming, i.e., heating the combined raw piece 30 in a furnace, possibly above an austenitizing temperature, specifically above Ac3. After heating in the furnace, the piece Petition 870250090735, dated 06 / 10 / 2025, page 22 / 91 The combined 18 / 20 rough piece 30 can be transferred to a press where the combined rough piece 30 is deformed to obtain the final shape of the unitary fire-resistant panel 100. During and immediately after forming, tempering can be carried out. In particular, tempering may include cooling above a critical cooling rate to obtain a martensitic microstructure. In some examples, tempering may be avoided in selected portions of the fire-resistant panel.

[0074] In some examples, the deformation can be done in a single operation.

[0075] Figure 6 schematically represents a unitary fire-resistant panel 100 according to an example in this disclosure. The unitary fire-resistant panel 100 is made from a plurality of blanks joined together to form a combined blank. The unitary fire-resistant panel is obtained after hot stamping of the combined blank.

[0076] In some examples, the unitary fire-resistant panel 100 can be placed between the passenger compartment and the engine compartment of a vehicle and can be joined to other parts of the vehicle structure, such as the hinge pillars and the floor, for example, by welding.

[0077] A firewall that is no longer a mere physical separation between the engine compartment and the passenger cabin can be provided. The unitary firewall panel 100 of the present disclosure may have greater rigidity and may have load paths that can transmit impact loads produced in a collision event to other parts of the vehicle designed to absorb such impact loads, for example, hinge pillars, A-pillars, rocker arms or the floor tunnel. Furthermore, the unitary firewall panel can be produced with fewer processes. Therefore, collision performance can be improved by avoiding the need to weld additional structural reinforcements to the firewall panel.

[0078] Figure 7 represents a flowchart of a method 200 for manufacturing a single fireproof panel for a vehicle. The method comprises providing a plurality of blanks 202; joining the blanks together to form a combined blank 204; hot stamping the combined blank to form a single fireproof panel 206. Petition 870250090735, dated 06 / 10 / 2025, page 23 / 91 19 / 20

[0079] In some examples, the plurality of blanks 10, 20 that form the combined blank 30 can be made of different materials. In some examples, the plurality of blanks 10, 20 can be made of ultra-high-strength steel or aluminum.

[0080] In some examples, the joining of the blanks to one another to form a combined blank 202 may comprise the formation of one or more overlapping regions 40, 50, 60 formed by the partial overlapping of the blanks to one another.

[0081] Overlap regions provide increased thickness and can provide rigidity to the firewall and be used to disperse impact energy to other parts of the vehicle. Overlap regions can be arranged to provide load paths to direct loads to, for example, a hinge pillar, a floor, or a tunnel. Overlap regions can be arranged so that areas of the firewall that are joined to other parts of the vehicle structure have greater strength and rigidity.

[0082] In some examples, an overlapping region may be formed along a longitudinal direction of the unitary firewall. A unitary firewall that may be more rigid in a longitudinal direction and that may be able to distribute impact loads to the structural parts of the vehicle may be provided.

[0083] Hot stamping or hot forming of the combined blank to form a unitary fireproof panel 206 may involve the creation of different microstructures in the hot-formed fireproof panel. These different microstructures may be created by heating a combined blank 30 above the austenitizing temperature. In some instances, during and after forming, quenching may be performed. Quenching may involve cooling above a critical cooling rate to obtain a martensitic microstructure.

[0084] In some examples, different microstructures can be obtained by heating a combined blank 30 above the austenitizing temperature and then controlling the cooling of the combined blank 30 during the molding of the part. Petition 870250090735, dated 06 / 10 / 2025, page 24 / 91 20 / 20 rough combined 30 to form a unitary fire-resistant panel 100. In some examples, tempering may be avoided in selected portions of the unitary fire-resistant panel 100.

[0085] In some examples, hot stamping of the combined raw piece to form a unitary fire-resistant panel 206 can be done in a single operation.

[0086] Although only a number of examples have been disclosed here, other alternatives, modifications, uses and / or equivalents are possible. Furthermore, all possible combinations of the examples described are also covered. Thus, the scope of this disclosure should not be limited by particular examples, but should be determined only by a fair reading of the claims that follow.

Claims

CLAIMS 1. Method for manufacturing a unitary fireproof panel (100) for a vehicle, characterized in that it comprises: providing a plurality of blanks (10, 20); joining the blanks to form a combined blank (30); hot stamping the combined blank (30) to form the unitary fireproof panel (100), wherein the joining of the blanks comprises the formation of one or more overlapping regions (40, 50, 60) formed by the partial overlapping of the blanks with one another; and wherein an overlapping region (40) is formed along a longitudinal direction of the unitary fireproof panel; and / or wherein an overlapping region is formed along a vertical direction of the unitary fireproof panel (100) and is located on a first lateral side of the unitary fireproof panel and on a second lateral side of the unitary fireproof panel.

2. Method according to claim 1, characterized in that the overlapping region (40) formed along a longitudinal direction of the unitary fire-resistant panel extends along the entire length of the unitary fire-resistant panel.

3. Method according to claim 1, characterized in that the unitary fire-resistant panel comprises a substantially U-shaped overlapping region.

4. A method, according to any one of claims 1 to 3, characterized in that the width of an overlapping region is at least 5 cm.

5. A method, according to any one of claims 1 to 4, characterized in that the deformation is done in a single operation.

6. Method, according to any one of claims 1 to 5, characterized in that the combined blank piece (30) comprises at least one patch blank piece (70). Petition 870250090735, dated 06 / 10 / 2025, page 26 / 91 2 / 2 7. Method according to claim 6, characterized in that the patch blank (70) is arranged along a vertical direction of the combined blank.

8. Method according to claim 7, characterized in that the patch blank (70) is arranged on a first lateral side of the combined blank.

9. Method, according to any one of claims 6 to 8, characterized in that the patch blank (70) is disposed in a substantially central lower part of the combined blank.

10. A method, according to any one of claims 1 to 9, characterized in that the joining of the blanks comprises welding the blanks to each other.

11. Method according to claim 10, characterized in that the welding comprises laser welding.

12. Method, according to any one of claims 1 to 11, characterized in that the plurality of blanks (10, 20) are made of an ultra-high strength steel.

13. Method, according to any one of claims 1 to 11, characterized in that the plurality of blanks (10, 20) are made of aluminum.

14. Unitary fire-resistant panel (100), characterized in that it can be obtained by a method according to any of claims 1 to 13.

15. Vehicle, characterized in that it comprises the unitary fire-resistant panel (100) according to claim 14.

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