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WO-2026092556-A1 - HOT STAMPED COMPONENT AND MANUFACTURING METHOD THEREFOR

WO2026092556A1WO 2026092556 A1WO2026092556 A1WO 2026092556A1WO-2026092556-A1

Abstract

Disclosed is a hot stamped component, comprising Fe and inevitable impurities, and further comprising the following chemical elements in percentage by mass: 0.24-0.34% of C, 0.5-2.0% of Si, 2.0-4.0% of Mn, 0.05-1.0% of Al, and 0.03-0.1% of Nb. The microstructure of the hot stamped component comprises at least 60% of tempered martensite and 5-20% of austenite. Further disclosed is a method for manufacturing the hot stamped component, comprising the steps of: preparing a steel blank; hot stamping; first-stage quenching; second-stage quenching; and aging treatment. The hot-stamped component of the present invention effectively addresses and improves the problems of poor elongation and bending angle of 1300 MPa-grade hot-stamped components, and improves hot-stamped component crash performance.

Inventors

  • LIU, HAO
  • TAN, Ning
  • LIN, Guangtao
  • JIN, Xinyan

Assignees

  • 宝山钢铁股份有限公司

Dates

Publication Date
20260507
Application Date
20251030
Priority Date
20241030

Claims (15)

  1. A hot-stamped part containing Fe and unavoidable impurities, characterized in that it further contains the following chemical elements in the following mass percentages: C: 0.24-0.34%, Si: 0.5-2.0%, Mn: 2.0-4.0%, Al: 0.05-1.0%, Nb: 0.03-0.1%; The microstructure of the hot-stamped component contains at least 60% tempered martensite and 5-20% austenite.
  2. The hot-stamped component as described in claim 1 is characterized in that the mass percentage content of each chemical element is: C: 0.24-0.34%, Si: 0.5-2.0%, Mn: 2.0-4.0%, Al: 0.05-1.0%, Nb: 0.03-0.1%; balance Fe and unavoidable impurities.
  3. The hot-stamped component as described in claim 1 or 2 is characterized in that: the mass percentage content of Si element is 1.0-2.0%; and/or, the mass percentage content of Mn element is 3.0-4.0%; and/or, the mass percentage content of Al element is 0.1-1.0% or 0.1-0.8%.
  4. The hot-stamped component as described in any one of claims 1-3 is characterized in that it further contains at least one of the following chemical elements: 0 < Ti ≤ 0.15%; 0 < V ≤ 1.0%; 0 < Ni ≤ 1.0%; 0 < Cr ≤ 2.0%; 0 < Mo ≤ 1.0%; 0 < Cu ≤ 1.0%; 0 < Ca ≤ 0.01%; 0 < REM ≤ 0.1%.
  5. The hot-stamped part according to any one of claims 1-4 is characterized in that, in the unavoidable impurities, each impurity element satisfies at least one of the following: P≤0.05%, S≤0.01%, N≤0.01%, B≤0.0005%.
  6. The hot-stamped component as described in any one of claims 1-5 is characterized in that: its austenite shape factor K1 = γ1/γ0, and K1 ≥ 0.7, wherein γ1 represents the austenite content with a length-to-minor-diameter ratio of not less than 4, and γ0 represents the total austenite content; preferably, K1 is 0.7-1.0, such as 0.7-0.95; and/or its austenite composition factor K2 = M1/M2, and K2 ≥ 3, wherein M1 represents the mass percentage content of Mn element in austenite, and M2 represents the mass percentage content of Mn element in tempered martensite; preferably, K2 is 3.0-7.0, such as 3.0-6.5; and/or its austenite stability factor K3 = V1/V2, and K3 ≥ 1.5, wherein V1 represents the austenite transformation amount in the plastic stage of the tensile test at room temperature, and V2 represents the austenite transformation amount in the elastic stage of the tensile test at room temperature; preferably, K3 is 1.5-4.0.
  7. The hot-stamped component according to any one of claims 1-6 is characterized in that the microstructure contains particulate precipitates dispersed in the matrix, the particulate precipitates including TiC and Nb(C,N), and the diameter of the particulate precipitates is less than or equal to 30 nm.
  8. The hot-stamped component as described in claim 1 or 2 is characterized in that its surface is further covered with a plating layer and/or a coating layer.
  9. The hot-stamped component as described in claim 1 or 2 is characterized in that its tensile strength is ≥1300MPa, elongation A50 is ≥10%, uniform elongation is ≥8%, and VDA bending angle is ≥60°.
  10. The hot-stamped component as described in claim 9 is characterized in that: its tensile strength is ≥1380MPa, or ≥1420MPa, ≥1500MPa, or ≥1600MPa, or between 1300 and 1900MPa, such as 1400 to 1900MPa; and/or, its elongation A50 is 10 to 16%; and/or, its uniform elongation is 8 to 12%; and/or, its VDA bending angle is ≥65°, or between 60° and 75° or between 65° and 75°.
  11. The method for manufacturing a hot-stamped part according to any one of claims 1-10 is characterized in that it includes the following steps: Steel plates were produced; Hot stamping: Heat the steel plate to (Ac1+50)-(Ac3+150)℃ and hold for 2-15 minutes, then complete the hot stamping process. First stage of cooling: The hot-stamped parts are rapidly cooled to Ms-Mf and held at that temperature for 5-200 seconds; Second stage cooling: Cooling the component to below 100°C; Aging treatment: Reheat the component to 100-400℃, hold for 10-60 minutes, and then air cool to room temperature.
  12. The manufacturing method as described in claim 11 is characterized in that a reheating step is further provided between the first cooling step and the second cooling step: the hot-stamped part is reheated to Ms-500°C and held at that temperature for 10-300 seconds.
  13. The manufacturing method as described in claim 11 is characterized in that, in the first cooling step, the cooling rate is 30-100°C/s.
  14. The manufacturing method as described in claim 11 is characterized in that, in the second cooling step, the cooling rate is not higher than 30°C/s.
  15. The manufacturing method as described in claim 11 is characterized in that, after the aging treatment step, it further includes a step of plating a coating layer and/or applying a coating layer.

Description

A hot-stamped component and its manufacturing method Technical Field This invention relates to a steel forming part and its manufacturing method, and more particularly to a hot stamping forming part and its manufacturing method. Background Technology The application of ultra-high strength steel can reduce vehicle weight while ensuring safety. Ultra-high strength steel applications in car bodies include two technical approaches: cold stamping and hot stamping. Hot stamping offers advantages such as ultra-high strength, ease of forming, and high dimensional accuracy. However, current hot stamping steels with strengths of 1300MPa and above suffer from insufficient plasticity and toughness, which can lead to cracking of the car body during a collision. Existing hot-stamping steel, tested according to the national standard GB/T228 Metallic Materials, room temperature tensile testing method, uses P6 sample, A50 gauge length, with a typical elongation of 6%. The VDA bending angle is tested according to VDA238-100 Metallic Materials, plate bending test, with a typical thickness of 1.5mm and the indenter parallel to the rolling direction, measuring a typical bending angle of 50°. In existing technologies, there is limited research, both domestically and internationally, on ultra-high strength hot-stamping components that simultaneously improve plasticity and toughness. Among these: For example, Chinese patent document CN108474081A, published on August 31, 2018, entitled "Steel for Stamping and Forming and Forming Components Thereof and Heat Treatment Method", discloses a steel for stamping and forming and forming components thereof and heat treatment method. The steel has a Mn content of 5-9.5% and contains 30-60% retained austenite in its microstructure. The purpose is to obtain steel with a yield strength of 0.5-1.2 GPa, a strength of 1.0-1.5 GPa, and a strength-ductility product ≥25 GPa%. The above patent document mainly obtains high strength-ductility product by introducing retained austenite through a higher manganese content. However, steel with a Mn content of more than 5% is more difficult to manufacture and has a higher cost. For example, Chinese patent document CN114959514A, published on August 30, 2022, entitled "Method for producing high-strength steel parts with improved ductility and parts obtained by said method", discloses a method for producing high-strength steel parts with improved ductility and parts obtained by said method. The parts contain 0.25-2% Ni element, and the number of Ni element diffusion enrichment particles on the surface is controlled, with the aim of improving the ductility of hot stamping steel. Summary of the Invention One of the objectives of this invention is to provide a hot-stamped component that, by controlling its chemical composition ratio and regulating its microstructure, can achieve ultra-high strength, plasticity, and toughness, and has excellent impact performance. To achieve the above objectives, the present invention provides a hot-stamped component containing Fe and unavoidable impurities, and further containing the following chemical elements in the following mass percentages: C: 0.24-0.34%, Si: 0.5-2.0%, Mn: 2.0-4.0%, Al: 0.05-1.0%, Nb: 0.03-0.1%; The microstructure of the hot-stamped component comprises at least 60% tempered martensite and 5-20% austenite. In this invention, when the proportion of tempered martensite in the microstructure is less than 60%, the tensile strength requirement of this invention cannot be met. The plasticity improvement of this invention mainly relies on austenite, which has high mechanical stability. During the tensile test of hot-stamped parts, the austenite in the microstructure undergoes a TRIP effect, increasing the material's work hardening rate and thus increasing plasticity, especially increasing the uniform elongation of the material. However, when the proportion of austenite in the microstructure is less than 5%, it affects the elongation and uniform elongation of the hot-stamped parts. When the proportion of austenite in the microstructure is greater than 20%, more alloying elements need to be added, and the stability of austenite will be affected. Furthermore, in the hot-stamped component described in this invention, the mass percentage content of each chemical element is as follows: C: 0.24-0.34%, Si: 0.5-2.0%, Mn: 2.0-4.0%, Al: 0.05-1.0%, Nb: 0.03-0.1%; balance Fe and unavoidable impurities. The design principles of each chemical element in the hot-stamped component of this invention are as follows: C: In the hot-stamped components described in this invention, carbon (C) is a key element for strength. When the mass percentage content of C is too low, it is difficult to achieve the target strength of 1300 MPa for the hot-stamped components. When the mass percentage content of C is too high, the plasticity, toughness, weldability, and resistance to delayed cracking of the hot-stamped components deteriorate. Therefore, in