A lightweight, high-strength, high-energy-absorbing porous TWIP steel and its preparation method

Abstract

The present invention discloses a lightweight, high-strength, high-energy-absorbing porous TWIP steel and a preparation method thereof. High-purity metal Fe, Mn powder and high-purity graphite are weighed and mixed in a certain proportion, and then mechanical alloying (MA), pore formation and high-temperature sintering are performed in sequence to obtain porous structure TWIP steel with different pore sizes and porosities. The alloy has the characteristics of light weight, high specific strength and high energy absorption, and can be used as a new generation of impact-resistant, buffering and energy-absorbing materials in many fields. At present, the research and development of porous metals mainly focuses on aluminum, copper, titanium, magnesium, nickel alloys, stainless steel, etc., and there are almost no reports on the porous preparation of TWIP steel. The present invention adopts a formed powder sintering method, and utilizes MA combined with pore formation and high-temperature sintering to realize the direct preparation of lightweight porous TWIP steel with controllable pore size and porosity. The unique TWIP effect and high work hardening ability of TWIP steel are utilized to obtain a higher specific strength and extremely high buffering and energy-absorbing ability.

Description

Technical Field

[0001] The present invention relates to the field of preparation of advanced metal materials, and in particular to a lightweight, high-strength, high-energy-absorbing porous TWIP steel and a preparation method thereof. Background Art

[0002] Porous metal is an engineering material with both structural and functional properties. Composed of a metal matrix and pores, it boasts advantages such as lightweight, large specific surface area, high specific strength, excellent energy absorption, and thermal insulation. As a functional structural material, it has extensive industrial applications. In particular, in the automotive, mechanical, and aerospace sectors, the use of porous metals can effectively reduce the weight of mechanical devices such as vehicles, aircraft, and spacecraft, achieving lightweighting and promoting energy conservation and emission reduction. Furthermore, the material's excellent energy absorption properties can enhance the impact resistance and energy absorption capacity of mechanical devices, reduce the degree of deformation and damage caused by impact, and effectively improve the safety of drivers and passengers. As a lightweight structural material, porous metal's excellent energy absorption properties are highly compatible with the development needs of the automotive, mechanical, and aerospace industries. Therefore, continued research is necessary, particularly the development of new, advanced porous metal materials to further enhance their overall performance, particularly their energy absorption properties. The goal is to significantly improve the lightweighting of mechanical devices while significantly enhancing their resistance to impact deformation, ultimately increasing the safety of the devices themselves and their passengers. This also aligns with the national green development requirements for energy conservation and emission reduction.

[0003] However, current research on porous metals primarily focuses on iron, nickel, copper, aluminum, cobalt, chromium, gold, silver, and their alloys, titanium alloys, and stainless steel. Twining-induced plasticity (TWIP) steel, a new high-manganese alloy steel, exhibits great potential for application in modern engineering fields such as automotive, rail transportation, aerospace, and defense due to its high strength, ultra-high energy absorption and efficiency, as well as excellent formability and weather resistance. Currently, research and application of this alloy primarily relies on bulk materials formed from traditional induction melting and ingot casting combined with various deformation and heat treatment processes. Considering the need for lightweight mechanical devices and the excellent energy absorption properties of this alloy, a lightweight porous TWIP steel with high specific strength and high energy absorption is being designed and prepared. Currently, there are few reports on the direct preparation of porous TWIP steel using powder metallurgy. Powder metallurgy, as an advanced manufacturing technology that integrates material preparation and part forming, offers energy conservation, material conservation, high efficiency, final formability, and low pollution. It boasts low cost, high efficiency, easily controllable microscopic features such as pore size and distribution, and simple operation.

[0004] Therefore, the present invention intends to use the molded powder sintering method, MA combined with pore formation and high-temperature sintering technology to prepare a porous TWIP steel with controllable pore size and porosity, thereby achieving higher specific strength and high energy absorption. It is hoped that this will provide a certain reference for the research of porous TWIP steel, increase the engineering application methods of the material, and expand its application range. Summary of the Invention

[0005] The object of the present invention is to provide a lightweight, high-strength, high-energy-absorbing porous TWIP steel and a preparation method thereof, so as to solve the problems raised in the above-mentioned background technology.

[0006] To achieve the above object, the present invention provides the following technical solutions:

[0007] A lightweight, high-strength, high-energy-absorbing porous TWIP steel. The chemical composition of the alloy steel is as follows: Mn: 18-23; C: 0.2-0.6; P≤0.008; S≤0.005; the remainder is Fe. The structure is a single austenite composed of a matrix and pores, with a porosity of 10%-80% and a controllable pore diameter of 0.1-0.6 mm.

[0008] A method for preparing lightweight, high-strength, high-energy-absorbing porous TWIP steel comprises the following steps:

[0009] (1) Mechanical alloying: According to the designed component ratio, the raw material powder is placed in a planetary ball mill with a ball-to-material ratio of 10:1 and a ball milling speed of 200 r / min. The ball milling is carried out under argon protection for 40-80 hours to obtain a fully alloyed Fe-Mn-C alloy powder with an average particle size range of 10-60 μm.

[0010] (2) Mixing and pressing: Alloy powder and ammonium bicarbonate particles with a particle size of 0.1-0.6 mm are weighed according to a certain ratio, placed in a V-type mixer, mixed evenly for 1-2 hours, placed in a φ12 mm cylindrical mold, and cold pressed at 200 MPa;

[0011] (3) Pre-sintering and pore formation: The pressed alloy block is placed in a tubular furnace and pre-sintered at 200°C for 3 h under the protection of flowing high-purity argon gas, and the furnace is cooled to remove ammonium bicarbonate particles and complete pore formation;

[0012] (4) High-temperature sintering: The porous block is placed in a high-temperature sintering furnace and sintered at 1050-1250°C for 2-3 hours under argon protection. The furnace is then cooled to obtain a porous cylindrical block with a diameter of 12 mm and a height of 12 mm.

[0013] Compared with the prior art, the present invention has the following beneficial effects:

[0014] The present invention provides a lightweight, high-strength, high-energy-absorbing porous TWIP steel and its preparation, which for the first time utilizes mechanical alloying combined with powder forming and sintering technology to achieve the direct preparation of lightweight porous TWIP steel with controllable pore size and porosity. In view of the unique plastic deformation mechanism and high work hardening ability of this material, combined with its porous structure, it has excellent energy absorption while achieving high specific strength. It can be used as an ideal functional structural material and applied to certain engineering fields with high requirements for lightweight and impact-resistant buffering protection. In addition, the preparation method is efficient and convenient, and can adjust the sintering mold according to actual engineering needs or component structure to achieve direct forming of specific products, meeting the advanced manufacturing requirements of high efficiency, energy saving, and green environmental protection. The Fe-Mn-C pre-alloyed powder prepared by the present invention and the obtained porous TWIP steel microstructure and main mechanical properties are as follows: Figure 1 、 2 As shown. Figure 1 It can be seen that the porous TWIP steel prepared by the present invention has a fine pore structure, uniform pore distribution, good sintering degree of powder particles, and exhibits high metallic luster. BRIEF DESCRIPTION OF THE DRAWINGS

[0015] Figure 1 These are TWIP steel pre-alloyed powder and porous TWIP steel sintered samples prepared by MA.

[0016] Figure 2 Quasi-static compression curves of porous TWIP steels with different porosities. DETAILED DESCRIPTION

[0017] The technical solution of this patent is further described in detail below in conjunction with specific implementation methods.

[0018] See also Figure 1-2 A lightweight, high-strength, high-energy-absorbing porous TWIP steel. The chemical composition of the alloy steel is as follows (wt.%): Mn 18-23; C 0.2-0.6; P≤0.008; S≤0.005; the remainder is Fe. Its structure is a single austenite composed of a matrix and pores, with a controllable porosity of 10%-80% and a pore diameter of 0.1-0.6 mm.

[0019] The preparation of porous alloy specifically includes the following steps:

[0020] (1) Mechanical alloying: According to the designed component ratio, the raw material powder is placed in a planetary ball mill with a ball-to-material ratio of 10:1 and a ball milling speed of 200 r / min. The ball milling is carried out under argon protection for 40-80 hours to obtain a fully alloyed Fe-Mn-C alloy powder with an average particle size range of 10-60 μm.

[0021] (2) Mixing and pressing: Alloy powder and ammonium bicarbonate particles with a particle size of 0.1-0.6 mm are weighed according to a certain ratio, placed in a V-type mixer, mixed evenly for 1-2 hours, placed in a φ12 mm cylindrical mold, and cold pressed at 200 MPa;

[0022] (3) Pre-sintering and pore formation: The pressed alloy block is placed in a tubular furnace and pre-sintered at 200°C for 3 h under the protection of flowing high-purity argon gas, and the furnace is cooled to remove ammonium bicarbonate particles and complete pore formation;

[0023] (4) High-temperature sintering: The porous block is placed in a high-temperature sintering furnace and sintered at 1050-1250°C for 2-3 hours under argon protection. The furnace is then cooled to obtain a porous cylindrical block with a diameter of 12 mm and a height of 12 mm.

[0024] (5) Processing the heat-treated cylindrical block into a φ6×8 mm cylindrical compression specimen;

[0025] (6) Ultrasonic cleaning of the sample in anhydrous ethanol for 10 min to remove oil stains and drying in a drying oven;

[0026] (7) Compression tests were carried out on a TMS universal material testing machine at a compression rate of 0.8 mm / min. The material showed high compressive yield strength (50-190 MPa), compressive strength and energy absorption.

[0027] The above describes in detail the preferred embodiments of this patent, but this patent is not limited to the above embodiments. Various changes can be made within the knowledge of ordinary technicians in this field without departing from the purpose of this patent.

Claims

1. A lightweight, high-strength, high-energy-absorbing porous TWIP steel, characterized in that: The mass percentage of the chemical composition of the steel is recorded as: Mn: 18-23%; C: 0.2-0.6%; P≤0.008%; S≤0.005%; the rest is Fe; Its structure is single austenite, consisting of matrix and pores, with a porosity of 10%-80% and a pore diameter of 0.1-0.6mm; The method for preparing the steel comprises the following steps: (1) Mechanical alloying: The raw material powders were placed into a planetary ball mill according to the designed component ratio, with a ball-to-material ratio of 10:1 and a ball milling speed of 200 r / min. The milling was carried out under argon protection for 40-80 h to obtain a fully alloyed Fe-Mn-C alloy powder with an average particle size range of 10-60 μm. (2) Mixing and pressing: Weigh the alloy powder and ammonium bicarbonate particles with a particle size of 0.1-0.6 mm in a certain proportion, put them into a V-type mixer, mix them evenly for 1-2 hours, put them into a φ12 mm cylindrical mold, and cold press them at 200 MPa; (3) Pre-sintering and pore formation: The pressed alloy block is placed in a tubular furnace and pre-sintered at 200°C for 3 h under the protection of flowing high-purity argon gas, and the furnace is cooled to remove ammonium bicarbonate particles and complete pore formation; (4) High-temperature sintering: The porous block is placed in a high-temperature sintering furnace and sintered at 1050-1250°C for 2-3 hours under argon protection. The furnace is then cooled to obtain a porous cylindrical block with a diameter of 12 mm and a height of 12 mm.

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