Ultra-thin high ductility steel strip for fast charging tail plug and manufacturing process thereof

Abstract

This invention relates to the field of steel strip technology for fast charging connectors, and more particularly to an ultra-thin, high-ductility steel strip for fast charging connectors and its manufacturing process. The steel strip includes a main body, which comprises an application section in the middle and bent sections on both sides of the application section. The uniform thickness of the main body is 0.05mm to 0.15mm. The chemical composition of the main body, by mass percentage, includes: C: 0.03% to 0.08%, Si: 0.30% to 1.00%, Mn: 1.00% to 2.50%, and Ni: 8.00% to 12.00%. Cr: 18.00%~20.00%, N: 0.01%~0.15%, Cu: 0.10%~0.50%, P≤0.035%, S≤0.020%, with the balance being Fe and unavoidable impurities; the metallographic structure of the main body of the steel strip is austenite, with a grain size grade of 7~9. In this invention, through the setting of the main body of the steel strip, temporary internal support components and other structures, the ultra-thin high-ductility steel strip for fast charging tail plugs achieves the dual advantages of high ductility and morphological stability through the synergistic optimization of material composition, microstructure and macrostructure.

Description

Technical Field

[0001] This invention relates to the field of steel strip technology for fast charging tail plugs, specifically to an ultra-thin, high-ductility steel strip for fast charging tail plugs and its manufacturing process. Background Technology

[0002] With the rapid development of fast charging technology, USB-C, Lightning and other fast charging interfaces have become standard configurations for consumer electronics products. The metal shell of the fast charging connector is usually formed by deep drawing process. This process requires the raw material to be ultra-thin stainless steel strip and to have excellent ductility to meet the forming requirements of complex three-dimensional structures.

[0003] However, existing steel strips cannot simultaneously meet the dual requirements of ultra-thinness and high ductility. On the one hand, when conventional stainless steel strips are rolled to below 0.15mm, defects such as edge cracks and pinholes are prone to occur due to improper grain control or high impurity content, resulting in a significant reduction in yield. On the other hand, when reducing the alloy element content or increasing the annealing temperature to achieve high ductility, the steel strip strength is insufficient, with yield strength often below 200MPa. Wrinkling is easily generated during deep drawing. More importantly, existing ultra-thin high-ductility steel strips are extremely prone to ductile deformation under non-use conditions such as transportation and storage, due to their thickness... With its extremely thin thickness and low yield strength, the steel strip is prone to irreversible elongation due to local grain slippage under winding tension, its own weight, or external forces, resulting in edge wavy or overall unevenness. At the same time, after the steel strip is wound into a coil, the interlayer pressure distribution is uneven, and the radial stiffness is insufficient under ultra-thin specifications, which easily leads to defects such as coil collapse and interlayer slippage. The above deformation problems directly affect the quality of subsequent processing and forming, resulting in dimensional deviations of the tail plug shell, surface scratches, or even cracks, causing material scrap and reduced production efficiency. Therefore, in view of the above problems, an ultra-thin high-ductility steel strip for fast charging tail plugs and its manufacturing process are proposed. Summary of the Invention

[0004] The purpose of this invention is to provide an ultra-thin, high-ductility steel strip for fast charging tail plugs and its manufacturing process, so as to solve the problem that existing steel strips cannot simultaneously meet the dual requirements of ultra-thinness and high ductility, and are prone to deformation during transportation and storage under ultra-thin and high-ductility specifications.

[0005] To achieve the above objectives, the present invention provides the following technical solution: An ultra-thin, high-ductility steel strip for fast-charging charging plugs includes a steel strip body, which is composed of an application section in the middle and bending sections on both sides of the application section. The uniform thickness of the steel strip body is 0.05mm to 0.15mm. The chemical composition of the steel strip body, by mass percentage, includes: C: 0.03% to 0.08%, Si: 0.30% to 1.00%, Mn: 1.00% to 2.50%, Ni: 8.00% to 12.00%, Cr: 18.00% to 20.00%, N: 0.01% to 0.15%, Cu: 0.10% to 0.50%, P≤0.035%, S≤0.020%, with the balance being Fe and unavoidable impurities. The metallographic structure of the steel strip body is austenite with a grain size grade of 7 to 9. The elongation of the steel strip body along the rolling direction is ≥40%, and its yield strength is 250 MPa to 350 MPa. A bending groove for bending is provided between the bending section and the application section. A removable temporary inner support assembly is provided on the upper side of the steel strip body. The temporary inner support assembly includes a support strip covering the upper side of the application section. Elastic hollow support tubes are fixedly connected to both sides of the temporary inner support assembly. The elastic hollow support tubes are used to be embedded in the enclosing space formed by the bending of the bending section. Adhesive tape is fixedly connected to both sides of the upper end face of the support strip. The adhesive tape is used to bond and fix to the inner wall of the bent section after bending. Notches are provided at the inner wall of the bent section. The notches are used for the breakage of the bent section, so that the temporary inner support assembly can be removed as a whole.

[0006] Preferably, the sum of the mass percentages of Ni and N in the main chemical composition of the steel strip satisfies: 10.0%≤Ni+N≤12.5%, the thickness tolerance of the main steel strip is ±0.01mm, and the thickness of the application section and the bending section are the same.

[0007] Preferably, the elastic hollow support tube is made of thermoplastic polyurethane, the outer diameter of the elastic hollow support tube is 3mm to 5mm, and the wall thickness of the elastic hollow support tube is 0.5mm to 1.0mm.

[0008] Preferably, the bent portion is a flat extension of the edge of the steel strip body before bending, the notch is a V-shaped groove structure, and the depth of the notch is 60% to 70% of the thickness of the steel strip body.

[0009] Preferably, the support strip is made of polyester film or polyimide film, and the elastic modulus of the support strip is ≥2GPa and the elongation at break is ≤30% to provide in-plane rigid constraint and prevent the application part from plastically stretching during non-application processes.

[0010] Preferably, the adhesive tape is a pressure-sensitive adhesive layer with an adhesive strength of 1 N / cm to 3 N / cm, and the adhesive tape only contacts the bent portion.

[0011] Preferably, a manufacturing process includes the following steps: S1. Smelting and continuous casting: Using a converter or electric furnace for primary smelting, the molten steel is prepared according to the following mass percentages: C: 0.03%–0.08%, Si: 0.30%–1.00%, Mn: 1.00%–2.50%, Ni: 8.00%–12.00%, Cr: 18.00%–20.00%, N: 0.01%–0.15%, Cu: 0.10%–0.50%, P≤0.035%, S≤0.020%, with the balance being Fe and unavoidable impurities. The prepared molten steel is then refined through argon-oxygen decarburization or vacuum oxygen decarburization, with controlled... The dissolved oxygen content in the molten steel is ≤0.0050%, and the hydrogen content is ≤0.0003%, ensuring that the Ni and N content meets the requirement of Ni+N=10.0%~12.5%. Then, the refined molten steel is poured into the continuous casting machine, and the superheat of the molten steel in the tundish is controlled at 15℃~35℃. The continuous casting speed is 0.8~1.2m / min. Electromagnetic stirring technology is used to suppress the growth of columnar crystals and cast into slabs. The slabs are then subjected to online grinding or flame cleaning to remove surface cracks and slag inclusions with a depth ≥2mm, ensuring that the surface roughness Ra of the slabs is ≤25μm. Finally, the slabs are slowly cooled to room temperature. S2. Hot rolling annealing: The slab is heated to 1150℃~1250℃ and held for 1.5~3.0h to allow the alloying elements to fully dissolve. Then, it is rolled in multiple passes on a hot continuous rolling mill with an initial rolling temperature of 1050℃~1150℃ and a final rolling temperature of 850℃~950℃. The cumulative reduction rate is ≥90%, and the slab is rolled into a hot-rolled strip with a thickness of 2.0mm~3.0mm. The hot-rolled strip is then laminar cooled to 550℃~650℃ at a cooling rate of 15℃ / s~30℃ / s and coiled into a hot-rolled coil. The hot-rolled coil is then continuously annealed at a temperature of 1000℃~1100℃ for 1~3min to fully austenitize the hot-rolled structure and eliminate work hardening. Subsequently, the coil is pickled to remove the iron oxide scale, resulting in a hot-rolled pickled coil with a smooth surface, a grain size of 5~7, and a thickness of 2.0mm~3.0mm. S3. Cold rolling: After uncoiling and trimming the ends of the hot-rolled pickled coil, it is fed into a 20-roll Sendzimir multi-roll mill for 5-7 passes of cold rolling. The rolling oil temperature is 40℃-60℃, and the strip crown is controlled to be ≤5I and the flatness to be ≤10I. The first pass reduction rate is 25%-35%, the last pass reduction rate is 15%-25%, and the cumulative reduction rate is ≥87%. The steel strip is rolled from a thickness of 2.0mm-3.0mm to 0.05mm-0.15mm. By controlling the rolling force and tension matching of each pass, the steel strip is free of cracks and edge breaks, resulting in a cold-rolled hard steel strip with a thickness tolerance of ±0.01mm and a surface roughness Ra≤0.8μm. S4. Continuous annealing: Cold-rolled hardened steel strip is passed through a continuous annealing furnace under a protective atmosphere of mixed hydrogen and nitrogen. The hydrogen gas fraction is 25%–75%, the dew point is ≤-40℃, the annealing temperature is 1050℃–1150℃, the strip speed is 30–80 m / min, and the annealing time is 30s–120s. This causes the deformed grains generated by cold rolling to recrystallize and grow uniformly, controlling the grain size to be 10μm–25μm, the grain size grade to be 7–9, and the {111} crystal orientation density in the austenite matrix to be ≥60%. After annealing, the strip is rapidly cooled to room temperature at a cooling rate of 50℃ / s–100℃ / s to obtain a recrystallized annealed steel strip with an elongation ≥40% along the rolling direction and a yield strength of 250MPa–350MPa. S5. Slitting: The recrystallized annealed steel strip is fed into a precision slitting unit. Using a disc shear or roller shear, the strip is slitted according to the required width. The slitting speed is 100–300 m / min, with burr height controlled to ≤0.03 mm and width tolerance to ±0.05 mm. The slitting process yields the main body of the steel strip, which has an application section in the middle and bending sections on both sides. Online surface quality inspection is performed on the slitting steel strip, removing any strips with edge cracks or scratches. S6. Processing notches: The slit steel strip body is fed into a punching or laser etching equipment. A bending groove is processed between the application section and the bending section. A notch for breaking is processed at the bending section. It is formed by laser etching or mechanical stamping. During the processing, a vision inspection system is used to monitor the position accuracy of the notch online and reject defective products with uneven notch depth or position deviation. S7. Assembly support: The steel strip body with the notched part is fed into the automatic laying machine or manual assembly table and laid flat; the support strip of the temporary inner support component is laid on the upper surface of the application part, so that the two sides of the support strip are aligned with the bending groove; the elastic hollow support tube is placed on both sides of the support strip and located on the upper side of the bending part; with the bending groove as the bending starting point, the two sides of the bending part are bent inward by 180° by bending machine or manual flanging, so that the bending part covers the elastic hollow support tube; the bending part is bonded and fixed to the support strip by adhesive tape, so that the elastic hollow support tube is used to support the bending part to maintain the bending shape, while the support strip is tensioned to restrain the application part to prevent it from stretching and deforming; S8. Winding: The steel strip body equipped with the temporary inner support assembly is fed into the winding machine and wound at a tension of 5-15 N / mm², controlling the outer diameter of the roll at 800-1500 mm. The winding tension is uniform, resulting in the finished roll. During storage and transportation, the support straps of the temporary inner support assembly are tensioned on the upper surface of the application section to prevent stretching deformation of the application section with in-plane rigid constraint. At the same time, the bending section forms an edge reinforcement structure after bending and wrapping the elastic hollow support tube, providing edge rigid support to prevent the roll from collapsing. When using, the roll is unwound and laid flat. Pressure is applied to the bend through an external pressure device; because the notch for breaking is opened on the bend, the thickness of the bend becomes thinner at this point; when the external pressure exceeds the supporting force of the elastic hollow support tube, the elastic hollow support tube is crushed and loses its supporting function, and the bent end of the bend closes inward under pressure, causing the bend to break in a controlled manner from the notch; since the bend and the support strip are bonded together by adhesive tape, the temporary inner support assembly can be peeled off and removed from the application part along with the broken bend, exposing a flat and residue-free application part for subsequent stamping processing of the fast charging tail plug.

[0012] Compared with the prior art, the beneficial effects of the present invention are: In this invention, by designing a steel strip body and temporary internal support components, the morphological stability of the ultra-thin, high-ductility steel strip in its non-use state and its forming performance in its use state are unified. On the one hand, the steel strip body adopts an optimized chemical composition design, controlling the sum of the mass percentages of Ni and N to be 10.0%–12.5%, and combining it with an austenitic structure of grain size 7–9, so that the steel strip maintains high ductility with an elongation of ≥40% even in ultra-thin specifications with a thickness of 0.05mm–0.15mm, meeting the stringent requirements of deep drawing forming for fast charging tail inserts. At the same time, the yield strength is controlled at 250MPa–350MPa to ensure sufficient anti-wrinkling ability during stamping. On the other hand, the temporary internal support components fundamentally solve the problem of ductility deformation during the transportation and storage of ultra-thin steel strips. The support belt uses in-plane rigid constraint to prevent plastic ductility in the application part of the steel strip body, while the elastic hollow support tube supports the bent part to maintain the bent shape. The synergistic effect of the two ensures that the steel strip body remains flat and tight in the winding state. This invention eliminates defects such as coil collapse and interlayer slippage, and provides edge rigid support at the bend, significantly improving the overall rigidity of the coil. Furthermore, the pre-designed notch for breaking facilitates controlled fracture of the bend along the notch during subsequent use, allowing the temporary internal support assembly to be removed along with the fractured bend, exposing a smooth, residue-free application section for stamping, achieving a non-destructive separation of the protective and functional structures. Optimized uniform thickness design and ±0.01mm thickness tolerance control ensure precise matching of the deep-drawing die gap, reducing the forming scrap rate. This invention employs a complete process chain including smelting and continuous casting, hot rolling and annealing, cold rolling, continuous annealing, slitting, notch processing, assembly support, and coiling. By controlling key parameters in each process, it achieves synergistic optimization of material composition, microstructure, and macrostructure for ultra-thin, high-ductility steel strips used in fast-charging tail plugs. This gives the steel strip the dual advantages of high ductility and morphological stability, solving the problem that existing steel strips cannot simultaneously meet the dual requirements of ultra-thinness and high ductility, and are prone to deformation during transportation and storage in ultra-thin, high-ductility specifications. Attached Figure Description

[0013] Figure 1 This is a schematic diagram of the overall structure of the present invention; Figure 2 For the present invention Figure 1 A magnified structural diagram at point A; Figure 3 This is a schematic diagram of the composition of the steel strip body of the present invention.

[0014] In the diagram: 1. Steel strip main body; 11. Application section; 12. Bending section; 13. Bending groove; 14. Notch; 2. Temporary internal support assembly; 21. Support strip; 22. Elastic hollow support tube; 23. Adhesive strip. Detailed Implementation

[0015] Please see Figure 1-3The present invention provides a technical solution: An ultra-thin, high-ductility steel strip for fast charging connectors includes a steel strip body 1. The steel strip body 1 is composed of an application section 11 located in the middle and bending sections 12 located on both sides of the application section 11. The uniform thickness of the steel strip body 1 is 0.05mm to 0.15mm. The chemical composition of the steel strip body 1, by mass percentage, includes: C: 0.03% to 0.08%, Si: 0.30% to 1.00%, Mn: 1.00% to 2.50%, Ni: 8.00% to 12.00%, Cr: 18.00% to 20.00%, N: 0.01% to 0.15%, Cu: 0.10% to 0.50%, P≤0.035%, S≤0.020%, with the balance being Fe and unavoidable impurities. The metallographic structure of the steel strip body 1 is austenite with a grain size grade of 7 to 9. The elongation of the steel strip body 1 along the rolling direction is ≥40%, and its yield strength is 250 MPa to 350 MPa. A bending groove 13 for bending is provided between the bending part 12 and the application part 11. A removable temporary inner support assembly 2 is provided on the upper side of the steel strip body 1. The temporary inner support assembly 2 includes a support strip 21 covering the upper side of the application part 11. Elastic hollow support tubes 22 are fixedly connected to both the left and right sides of the temporary inner support assembly 2. The elastic hollow support tubes 22 are used to be embedded in the containment space formed by bending of the bending part 12. Adhesive tape 23 is fixedly connected to both sides of the upper end face of the support strip 21. The adhesive tape 23 is used to be bonded and fixed to the inner wall of the bent part 12 after bending. A notch 14 is provided at the inner wall of the bent part 12. The notch 14 is used for the breakage of the bent part 12, so that the temporary inner support assembly 2 can be removed as a whole.

[0016] The sum of the mass percentages of Ni and N in the chemical composition of the steel strip body 1 satisfies: 10.0% ≤ Ni + N ≤ 12.5%. The thickness tolerance of the steel strip body 1 is ±0.01 mm. The thickness of the application section 11 and the bending section 12 are the same. This configuration allows the steel strip body 1 to maintain excellent austenitic stability and forming accuracy while maintaining ultra-thin dimensions. The synergistic effect of Ni and N ensures that the austenitic structure does not undergo martensitic transformation during cold rolling to 0.05 mm to 0.15 mm, maintaining an elongation of ≥40%. High ductility and strict thickness tolerance control improve the matching accuracy of deep drawing die gaps, reducing forming defects caused by thickness fluctuations. The uniform thickness design avoids the complex process of differential thickness rolling, simplifying the production process and ensuring a clean and controllable fracture surface when the bent section 12 breaks. The elastic hollow support tube 22 is made of thermoplastic polyurethane, with an outer diameter of 3mm to 5mm and a wall thickness of 0.5mm to 1.0mm. This design allows the elastic hollow support tube 22 to bend... The fold 12 provides support; before bending, the fold 12 is a flat extension of the edge of the steel strip body 1. This design allows the fold 12 to be integrally formed with the steel strip body 1 before bending, eliminating the need for additional welding or assembly. The notch 14 is a V-shaped groove structure, with a depth of 60% to 70% of the thickness of the steel strip body 1. This design ensures that the fold 12 maintains sufficient strength while achieving controllable fracture under external pressure. The fracture surface is clean and does not extend to the application section 11, ensuring the integrity and flatness of the application section 11. The support strip 21 is made of polyester film or polyimide film. The elastic modulus of the support strip 21 is ≥2GPa and the elongation at break is ≤30% to provide in-plane rigid constraint and prevent the application part 11 from plastically stretching during non-application. The adhesive tape 23 is a pressure-sensitive adhesive layer with an adhesive strength of 1N / cm to 3N / cm. The adhesive tape 23 only contacts the bending part 12. This arrangement allows the bent part 12 to be peeled off from the application part 11 along with the entire temporary inner support assembly 2 after breakage without affecting the application part 11.

[0017] Workflow: The manufacturing and use of ultra-thin, high-ductility steel strip for fast-charging plugs are as follows: S1. Smelting and continuous casting: Primary smelting is carried out in a converter or electric furnace, with the following mass percentages of molten steel: C: 0.03%–0.08%, Si: 0.30%–1.00%, Mn: 1.00%–2.50%, Ni: 8.00%–12.00%, Cr: 18.00%–20.00%, N: 0.01%–0.15%, Cu: 0.10%–0.50%, P≤0.035%, S≤0.020%, with the balance being Fe and unavoidable impurities; the molten steel is then refined through argon-oxygen decarburization or vacuum oxygen decarburization, controlling... The dissolved oxygen content in the molten steel is ≤0.0050%, and the hydrogen content is ≤0.0003%, ensuring that the Ni and N content meets the requirement of Ni+N=10.0%~12.5%. The refined molten steel is then poured into a continuous casting machine, controlling the superheat of the molten steel in the tundish to be 15℃~35℃, and the continuous casting speed to be 0.8~1.2m / min. Electromagnetic stirring technology is used to suppress columnar crystal growth, casting into slabs. The slabs undergo online surface grinding or flame cleaning to remove surface cracks and inclusions with a depth ≥2mm, ensuring a surface roughness Ra≤25μm. They are then slowly cooled to room temperature. S2, hot rolling annealing: the slab is heated to 1150℃~1250℃ and held for 1.5 seconds. The alloying elements are fully dissolved over 3.0 hours, followed by multi-pass rolling on a hot continuous rolling mill. The initial rolling temperature is 1050℃~1150℃, the final rolling temperature is 850℃~950℃, and the cumulative reduction rate is ≥90%, resulting in a hot-rolled strip with a thickness of 2.0mm~3.0mm. The hot-rolled strip is then laminar cooled to 550℃~650℃ at a cooling rate of 15℃ / s~30℃ / s and coiled into a hot-rolled coil. The hot-rolled coil is then continuously annealed at a temperature of 1000℃~1100℃ for 1~3 minutes to fully austenitize the hot-rolled microstructure and eliminate work hardening. Subsequently, pickling is performed to remove the iron oxide scale, resulting in a smooth surface, a grain size of 5~7, and a thickness of [missing information]. 2.0mm~3.0mm hot-rolled pickled coils; S3, cold rolling: after uncoiling and trimming the ends, the hot-rolled pickled coils are fed into a 20-roll Sendzimir multi-roll mill for 5~7 passes of cold rolling. The rolling oil temperature is 40℃~60℃, and the strip crown is controlled to be ≤5I and the flatness to be ≤10I. The first pass reduction rate is 25%~35%, the last pass reduction rate is 15%~25%, and the cumulative reduction rate is ≥87%, rolling the steel strip from a thickness of 2.0mm~3.0mm to 0.05mm~0.15mm. By controlling the matching of rolling force and tension in each pass, the steel strip is free of cracks and edge breaks, resulting in a thickness tolerance of ±0.01mm and a surface roughness Ra≤0.8μm cold-rolled hard steel strip; S4, continuous annealing: the cold-rolled hard steel strip is passed through a continuous annealing furnace under a mixed hydrogen and nitrogen protective atmosphere, with a hydrogen gas integral of 25%–75%, a dew point ≤-40℃, an annealing temperature of 1050℃–1150℃, a strip speed of 30–80 m / min, and an annealing time of 30s–120s. This causes the deformed grains generated by cold rolling to recrystallize and grow uniformly, controlling the grain size to 10μm–25μm, the grain size grade to 7–9, and the {111} in the austenite matrix. The crystal orientation density is ≥60%; after annealing, it is rapidly cooled to room temperature at a cooling rate of 50℃ / s~100℃ / s to obtain recrystallized annealed steel strip with an elongation ≥40% along the rolling direction and a yield strength of 250MPa~350MPa; S5, slitting: the recrystallized annealed steel strip is fed into a precision slitting unit, and slitting is carried out according to the finished product width requirements using a disc shear or roller shear. The slitting speed is 100~300m / min, the burr height is controlled to be ≤0.03mm, and the width tolerance is ±0.0.5mm; After slitting, a steel strip body 1 is obtained, which has an application section 11 in the middle and bending sections 12 on both sides of the application section 11; The surface quality of the slitting steel strip body 1 is inspected online to remove defective products with edge cracks and scratches; S6, Processing notch 14, the slitting steel strip body 1 is fed into a punching or laser etching equipment, a bending groove 13 is processed between the application section 11 and the bending section 12, and a notch 14 for breaking is processed at the bending section 12, which is formed by laser etching or mechanical stamping. During the processing, a vision inspection system is used to monitor the position accuracy of the notch 14 online and remove defective products with uneven depth or positional deviation of the notch 14; S7 1. Assemble the support: The steel strip body 1, after processing the notch 14, is fed into an automatic laying machine or a manual assembly table and laid flat. The support strip 21 of the temporary inner support component 2 is laid on the upper surface of the application section 11, aligning the two side edges of the support strip 21 with the bending groove 13. Elastic hollow support tubes 22 are placed on both sides of the support strip 21, located above the bending section 12. Using the bending groove 13 as the starting point of the bend, the two bending sections 12 are bent inwards by 180° using a bending machine or manual flanging, so that the bending section 12 covers the elastic hollow support tube 22. The bending section 12 is then bonded and fixed to the support strip 21 using adhesive tape 23, allowing the elastic hollow support tube 22 to support the bending section 12 and maintain its bent shape. Simultaneously, the support strap 21 is tensioned to constrain the application section 11 and prevent it from stretching and deforming; S8, winding: the steel strip body 1 equipped with the temporary inner support assembly 2 is fed into the winding machine and wound with a tension of 5-15 N / mm², controlling the outer diameter of the roll to be 800-1500 mm, and the winding tension is uniform to obtain the finished roll; during storage and transportation, the support strap 21 of the temporary inner support assembly 2 is tensioned on the upper surface of the application section 11 to prevent the application section 11 from stretching and deforming with in-plane rigid constraint, while the bending section 12 bends and wraps around the elastic hollow support tube 22 to form an edge reinforcement structure, providing edge rigid support to prevent the roll from collapsing; when in use, the roll is unwound and flattened. The bending section 12 is subjected to pressure by an external pressure device. Because the notch 14 for breaking is opened on the bending section 12, the thickness of the bending section 12 becomes thinner at this point. When the external pressure exceeds the supporting force of the elastic hollow support tube 22, the elastic hollow support tube 22 is crushed and loses its supporting function. The bent end of the bending section 12 closes inward under pressure, causing the bending section 12 to fracture controllably at the notch 14. Because the bending section 12 and the support strip 21 are bonded together by the adhesive tape 23, the temporary inner support assembly 2 can be peeled off and removed from the application section 11 along with the broken bending section 12, exposing a flat and residue-free application section 11 for subsequent stamping processing of the fast charging tail plug.

[0018] This article uses specific examples to illustrate the principles and implementation methods of the present invention. The above examples are only for the purpose of helping to understand the method and core ideas of the present invention. The above descriptions are only preferred embodiments of the present invention. It should be noted that due to the limitations of textual expression, while there are objectively infinite specific structures, those skilled in the art can make several improvements, modifications, or changes without departing from the principles of the present invention, and can also combine the above technical features in an appropriate manner. These improvements, modifications, changes, or combinations, or the direct application of the inventive concept and technical solution to other situations without modification, should all be considered within the scope of protection of the present invention.

Claims

1. A thin, high-ductility steel strip for fast charging connectors, comprising a steel strip body (1), characterized in that: The steel strip body (1) is composed of an application section (11) located in the middle and bending sections (12) located on both sides of the application section (11). The uniform thickness of the steel strip body (1) is 0.05mm to 0.15mm. The chemical composition of the steel strip body (1) by mass percentage includes: C: 0.03% to 0.08%, Si: 0.30% to 1.00%, Mn: 1.00% to 2.50%, Ni: 8.00% to 12.00%, Cr: 18.00% to 20.00%, N: 0.01% to 0.15%, Cu: 0.10% to 0.50%, P≤0.035%, S≤0.020%, with the balance being Fe and unavoidable impurities. The metallographic structure of the steel strip body (1) is austenite with a grain size grade of 7 to 9. The elongation of the steel strip body (1) along the rolling direction is ≥40%, and its yield strength is 250 MPa to 350 MPa. A bending groove (13) for bending is provided between the bending part (12) and the application part (11). A removable temporary inner support assembly (2) is provided on the upper side of the steel strip body (1). The temporary inner support assembly (2) includes a support strip (21) covering the upper side of the application part (11). Elastic hollow support tubes (22) are fixedly connected to both the left and right sides of the temporary inner support assembly (2). The elastic hollow support tubes (22) are used to be embedded in the containment space formed by the bending part (12). Adhesive tape (23) is fixedly connected to both sides of the upper end face of the support strip (21). The adhesive tape (23) is used to be bonded and fixed to the inner wall of the bent part (12) after bending. A notch (14) is provided at the inner wall of the bent part (12). The notch (14) is used for the breakage of the bent part (12), so that the temporary inner support assembly (2) can be removed as a whole.

2. The ultra-thin, high-ductility steel strip for a fast-charging tail plug according to claim 1, characterized in that: The sum of the mass percentages of Ni and N in the chemical composition of the steel strip body (1) satisfies: 10.0%≤Ni+N≤12.5%, the thickness tolerance of the steel strip body (1) is ±0.01mm, and the thickness of the application part (11) is the same as that of the bending part (12).

3. The ultra-thin, high-ductility steel strip for a fast-charging tail plug according to claim 2, characterized in that: The elastic hollow support tube (22) is made of thermoplastic polyurethane. The outer diameter of the elastic hollow support tube (22) is 3mm to 5mm, and the wall thickness of the elastic hollow support tube (22) is 0.5mm to 1.0mm.

4. The ultra-thin, high-ductility steel strip for a fast-charging tail plug according to claim 3, characterized in that: Before bending, the bending section (12) is a flat extension of the edge of the steel strip body (1). The notch (14) is a V-shaped notch structure. The depth of the notch (14) is 60% to 70% of the thickness of the steel strip body (1).

5. The ultra-thin, high-ductility steel strip for a fast-charging tail plug according to claim 4, characterized in that: The support strip (21) is made of polyester film or polyimide film. The elastic modulus of the support strip (21) is ≥2GPa and the elongation at break is ≤30% to provide in-plane rigid constraint and prevent the application part (11) from plastically stretching during non-application.

6. The ultra-thin, high-ductility steel strip for a fast-charging tail plug according to claim 1, characterized in that: The adhesive tape (23) is a pressure-sensitive adhesive layer with an adhesive strength of 1N / cm to 3N / cm. The adhesive tape (23) only contacts the bent part (12).

7. A manufacturing process for an ultra-thin, high-ductility steel strip for a fast-charging tail plug as described in claims 1-6, characterized in that, Includes the following steps: S1. Smelting and continuous casting: Using a converter or electric furnace for primary smelting, the molten steel is prepared according to the following mass percentages: C: 0.03%–0.08%, Si: 0.30%–1.00%, Mn: 1.00%–2.50%, Ni: 8.00%–12.00%, Cr: 18.00%–20.00%, N: 0.01%–0.15%, Cu: 0.10%–0.50%, P≤0.035%, S≤0.020%, with the balance being Fe and unavoidable impurities. The prepared molten steel is then refined through argon-oxygen decarburization or vacuum oxygen decarburization, with controlled... The dissolved oxygen content in the molten steel is ≤0.0050%, and the hydrogen content is ≤0.0003%, ensuring that the Ni and N content meets the requirement of Ni+N=10.0%~12.5%. Then, the refined molten steel is poured into the continuous casting machine, and the superheat of the molten steel in the tundish is controlled at 15℃~35℃. The continuous casting speed is 0.8~1.2m / min. Electromagnetic stirring technology is used to suppress the growth of columnar crystals and cast into slabs. The slabs are then subjected to online grinding or flame cleaning to remove surface cracks and slag inclusions with a depth ≥2mm, ensuring that the surface roughness Ra of the slabs is ≤25μm. Finally, the slabs are slowly cooled to room temperature. S2. Hot rolling annealing: The slab is heated to 1150℃~1250℃ and held for 1.5~3.0h to allow the alloying elements to fully dissolve. Then, it is rolled in multiple passes on a hot continuous rolling mill with an initial rolling temperature of 1050℃~1150℃ and a final rolling temperature of 850℃~950℃. The cumulative reduction rate is ≥90%, and the slab is rolled into a hot-rolled strip with a thickness of 2.0mm~3.0mm. The hot-rolled strip is then laminar cooled to 550℃~650℃ at a cooling rate of 15℃ / s~30℃ / s and coiled into a hot-rolled coil. The hot-rolled coil is then continuously annealed at a temperature of 1000℃~1100℃ for 1~3min to fully austenitize the hot-rolled structure and eliminate work hardening. Subsequently, the coil is pickled to remove the iron oxide scale, resulting in a hot-rolled pickled coil with a smooth surface, a grain size of 5~7, and a thickness of 2.0mm~3.0mm. S3. Cold rolling: After uncoiling and trimming the ends of the hot-rolled pickled coil, it is fed into a 20-roll Sendzimir multi-roll mill for 5-7 passes of cold rolling. The rolling oil temperature is 40℃-60℃, and the strip crown is controlled to be ≤5I and the flatness to be ≤10I. The first pass reduction rate is 25%-35%, the last pass reduction rate is 15%-25%, and the cumulative reduction rate is ≥87%. The steel strip is rolled from a thickness of 2.0mm-3.0mm to 0.05mm-0.15mm. By controlling the rolling force and tension matching of each pass, the steel strip is free of cracks and edge breaks, resulting in a cold-rolled hard steel strip with a thickness tolerance of ±0.01mm and a surface roughness Ra≤0.8μm. S4. Continuous annealing: Cold-rolled hardened steel strip is passed through a continuous annealing furnace under a protective atmosphere of mixed hydrogen and nitrogen. The hydrogen gas fraction is 25%–75%, the dew point is ≤-40℃, the annealing temperature is 1050℃–1150℃, the strip speed is 30–80 m / min, and the annealing time is 30s–120s. This causes the deformed grains generated by cold rolling to recrystallize and grow uniformly, controlling the grain size to be 10μm–25μm, the grain size grade to be 7–9, and the {111} crystal orientation density in the austenite matrix to be ≥60%. After annealing, the strip is rapidly cooled to room temperature at a cooling rate of 50℃ / s–100℃ / s to obtain a recrystallized annealed steel strip with an elongation ≥40% along the rolling direction and a yield strength of 250MPa–350MPa. S5. Slitting: The recrystallized annealed steel strip is fed into a precision slitting unit. It is slitting according to the finished product width requirements using a disc shear or a roller shear. The slitting speed is 100-300 m / min, and the burr height is controlled to be ≤0.03 mm and the width tolerance is ±0.05 mm. After slitting, a steel strip body (1) is obtained, which has an application part (11) in the middle and a bending part (12) on both sides of the application part (11). The surface quality of the slitting steel strip body (1) is inspected online to remove products with edge cracks and scratches. S6. Processing notch (14): The steel strip body (1) after slitting is fed into the punching or laser etching equipment. A bending groove (13) is processed between the application part (11) and the bending part (12). A notch (14) for breaking is processed at the bending part (12). It is formed by laser etching or mechanical stamping. During the processing, a visual inspection system is used to monitor the position accuracy of the notch (14) online and reject defective products with uneven depth or positional deviation of the notch (14). S7. Assembly support: The steel strip body (1) after processing notch (14) is fed into an automatic laying machine or a manual assembly table and laid flat; the support strip (21) of the temporary inner support component (2) is laid on the upper surface of the application part (11) so that the two sides of the support strip (21) are aligned with the bending groove (13); the elastic hollow support tube (22) is placed on both sides of the support strip (21) and located on the upper side of the bending part (12); with the bending groove (13) as the bending starting point, the two sides of the bending part (12) are bent inward by 180° by bending machine or manual turning, so that the bending part (12) covers the elastic hollow support tube (22); the bending part (12) and the support strip (21) are bonded and fixed by adhesive tape (23), so that the elastic hollow support tube (22) is used to support the bending part (12) to maintain the bending shape, while the support strip (21) is tensioned to restrain the application part (11) to prevent it from stretching and deforming; S8. Winding: The steel strip body (1) equipped with the temporary inner support assembly (2) is fed into the winding machine and wound with a tension of 5-15 N / mm². The outer diameter of the roll is controlled to be 800-1500 mm, and the winding tension is uniform to obtain the finished roll. During storage and transportation, the support strip (21) of the temporary inner support assembly (2) is tensioned on the upper surface of the application part (11) to prevent the application part (11) from stretching and deforming with in-plane rigid constraint. At the same time, the bending part (12) bends and wraps the elastic hollow support tube (22) to form an edge reinforcement structure, providing edge rigid support to prevent the roll from collapsing. When in use, the roll is unwound and laid flat. External pressure is applied to the bending part (12). Pressure; Since the notch (14) for breaking is opened on the bend (12), the thickness of the bend (12) becomes thinner at this point; When the external pressure exceeds the supporting force of the elastic hollow support tube (22), the elastic hollow support tube (22) is crushed and loses its supporting function, and the bent end of the bend (12) closes inward under pressure, causing the bend (12) to break in a controllable manner from the notch (14); Since the bend (12) and the support strip (21) are bonded together by the adhesive tape (23), the temporary inner support assembly (2) can be peeled off and removed from the application part (11) along with the broken bend (12), exposing a flat and residue-free application part (11) for subsequent stamping processing of the fast charging tail plug.

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