A high toughness high strain rate impact resistant rod material and method of manufacture and use thereof

Abstract

This invention belongs to the field of metal material manufacturing, and relates to a high-strength, high-toughness, high-strain-rate impact-resistant rod material, its manufacturing method, and its application. The chemical composition of this material mainly includes carbon (C): 0.38–0.45%, silicon (Si): 0.17–0.37%, manganese (Mn): 0.50–0.80%, sulfur (S): ≤0.035%, phosphorus (P): ≤0.035%, chromium (Cr): 0.90–1.20%, molybdenum (Mo): 0.15–0.25%, vanadium (V): 0.02–0.08%, niobium (Nb): 0.01–0.05%, boron (B): 0.0005–0.003%, RE (composite rare earth): 0.001–0.02%, nickel (Ni): 0.20–0.50%, copper (Cu): 0.10–0.30%, tungsten (W): 0.01–0.05%, with the remainder being iron and unavoidable impurities. The proportions and contents of specific elements are subject to specific requirements. The preparation method includes homogenization, extrusion molding, austenitization, salt bath partitioning, induction hardening, and tempering. The resulting alloy rods have an ultrafine grain structure with a grain size of 1.0–5.0 μm, a surface finish Ra ≤ 0.8, a tensile strength exceeding 2000 MPa, a yield strength exceeding 1800 MPa, and an impact energy of not less than 40 J at -40℃. This material is used to manufacture structural components with high strength, high toughness, and good fatigue resistance, such as aerospace parts, key automotive components, and heavy machinery parts.

Description

Technical Field

[0001] This invention belongs to the field of metal material manufacturing technology, and in particular relates to a high-strength, high-toughness, high-strain-rate impact-resistant rod material, its manufacturing method, and its application. Background Technology

[0002] In applications involving high impact loads, high strain rates, and extreme environments, structural materials must possess excellent strength, toughness, and impact resistance to meet the stringent requirements of aerospace, military, armor protection, heavy machinery, and engineering machinery. While traditional high-strength alloy materials exhibit high strength, they often suffer from insufficient toughness, limited processing performance, and short fatigue life, making it difficult to maintain stable service under high strain rates and complex stress environments for extended periods. Furthermore, the large-scale manufacturing of existing high-strength steels and impact-resistant alloys is often hampered by defects such as inhomogeneous microstructure, compositional segregation, and high residual stress, leading to cracking and fracture in the prepared rod-shaped materials, thus affecting their service life and reliability. Therefore, developing a special alloy material that combines high strength, high toughness, and excellent dynamic impact performance, coupled with appropriate preparation and heat treatment processes, has become an important research direction for improving the impact resistance and extending the service life of related equipment.

[0003] Currently, most high-strength alloy materials on the market employ single hot working methods, such as traditional forging or rolling, which struggle to fully refine the microstructure and ensure stable mechanical properties. Simultaneously, existing heat treatment processes primarily rely on ordinary quenching and tempering, resulting in relatively crude microstructure control. This leads to limited impact absorption capacity under high strain rate conditions, making it difficult to simultaneously achieve high strength and high toughness. Furthermore, existing high-strength impact-resistant materials suffer from severe work hardening, high surface roughness, and poor wear resistance during processing, further limiting their adoption in high-end applications. Therefore, there is an urgent need to explore an optimized material composition design, combined with advanced forming and heat treatment processes, to achieve reliable application of materials under high impact load conditions, thereby improving the safety and service life of structural components.

[0004] To address the aforementioned problems, this invention innovatively designs a high-strength, high-toughness, high-strain-rate impact-resistant rod material and develops a comprehensive preparation process combining homogenization treatment, two-stage extrusion molding, precision mist cooling, austenitizing quenching, salt bath treatment, and induction tempering. This optimizes the material's microstructure and improves its overall mechanical properties and service stability. This material and process not only significantly enhance tensile strength, yield strength, low-temperature impact toughness, and high-strain-rate impact performance, but also possess excellent wear resistance and fatigue life. It can be widely used in aerospace components, vehicle armor, protective equipment, heavy machinery parts, and wear-resistant components for engineering machinery, meeting the demands of the high-end equipment manufacturing industry for high-performance special alloy materials.

[0005] Patent document CN 115611630 A discloses a method for preparing cemented carbide rods using an extrusion molding process. Based on the traditional extrusion process, this patent introduces a synergistic treatment step involving modified yttrium oxide and a modified zirconia agent, thereby optimizing the interfacial reaction between materials and significantly improving the product's hardness, strength, and wear resistance. Through ball milling, heat treatment, and plasma irradiation, a synergistic effect is achieved, ensuring the product possesses excellent overall performance. However, this process is relatively complex, requiring extremely high precision in controlling key parameters such as solution concentration, stirring speed, irradiation power, and time; even slight deviations can affect the final performance. Furthermore, this technology places high demands on production equipment, resulting in significant overall costs and a high technical threshold, limiting its widespread application in large-scale, economical production.

[0006] Patent document CN 116814931 A discloses a quenching and tempering heat treatment method for 42CrMo connecting rods. This method achieves one-time quenching and tempering through segmented heating, holding, cooling, and oil bath cooling processes, precisely controlling the austenitizing process of the workpiece to optimize the matching relationship between tensile strength and plasticity. Compared with traditional processes, this method eliminates the need for multiple heat treatments, effectively shortening the production cycle, reducing manufacturing costs, and minimizing oxidation, decarburization, and workpiece deformation, thus improving product quality. However, this process is relatively complex, requiring extremely high precision control of key parameters such as heating, holding, cooling rates, and transfer time. It relies on high-precision equipment and automated control systems, making operation difficult. In practical application, this process is susceptible to environmental factors and equipment stability, placing higher demands on production management and technical support.

[0007] While traditional manufacturing methods can improve the strength and hardness of materials to some extent, they struggle to achieve a synergistic optimization of high strength and high toughness. Especially under high strain rates and complex impact loads, the impact resistance, stability, and service life of materials remain limited. This invention aims to further refine the microstructure, reduce residual stress, and improve dynamic impact performance by optimizing material composition design and combining it with comprehensive preparation processes such as homogenization treatment, two-stage extrusion molding, precision mist cooling, austenitizing quenching, salt bath treatment, and induction tempering. This results in an organic combination of high strength, high toughness, and excellent impact resistance, meeting the stringent requirements of high-end equipment manufacturing for high-performance special alloy materials. Summary of the Invention

[0008] The purpose of this invention is to overcome the shortcomings of existing technologies and provide a method for preparing a high-strength, high-toughness, high-strain-rate impact-resistant bar material. This method optimizes the material composition design and combines homogenization treatment, two-stage extrusion molding, precision mist cooling, austenitizing quenching, salt bath treatment, and induction tempering processes to achieve deep refinement and homogenization of the material's microstructure, thereby significantly improving the material's tensile strength, yield strength, low-temperature impact toughness, and high-strain-rate impact performance. The process flow employed in this invention has high controllability and stability, effectively reducing residual stress, inhibiting work hardening, and simultaneously improving wear resistance and fatigue life.

[0009] The objective of this invention can be achieved through the following technical solutions:

[0010] A high-strength, high-toughness, high-strain-rate impact-resistant bar material, wherein the chemical composition of the high-strength, high-toughness, high-strain-rate impact-resistant bar comprises: carbon (C): 0.38–0.45%, silicon (Si): 0.17–0.37%, manganese (Mn): 0.50–0.80%, sulfur (S): ≤0.035%, phosphorus (P): ≤0.035%, chromium (Cr): 0.90–1.20%, molybdenum (Mo): 0.15–0.25%, vanadium (V): 0.02–0.08%, niobium (Nb): 0.01–0.05%, boron (B): 0.0005–0.003%, RE (composite rare earth): 0.001–0.02%, nickel (Ni): 0.20–0.50%, copper (Cu): 0.10–0.30%, tungsten (W): 0.01–0.05%, with the remainder being iron and unavoidable impurities.

[0011] Preferably, a high-strength, high-toughness, high-strain-rate impact-resistant bar material is provided, wherein the chemical composition of the high-strength, high-toughness, high-strain-rate impact-resistant bar comprises: carbon (C): 0.40–0.43%, silicon (Si): 0.20–0.35%, manganese (Mn): 0.60–0.75%, sulfur (S): ≤0.015%, phosphorus (P): ≤0.015%, chromium (Cr): 0.90–1.20%, molybdenum (Mo): 0.15–0.25%, vanadium (V): 0.02–0.08%, niobium (Nb): 0.01–0.05%, boron (B): 0.0005–0.003%, RE (composite rare earth): 0.001–0.02%, nickel (Ni): 0.20–0.50%, copper (Cu): 0.10–0.30%, tungsten (W): 0.01–0.05%, with the remainder being iron and unavoidable impurities.

[0012] Preferably, the chemical composition of the high-strength, high-toughness, high-strain-rate impact-resistant bar includes carbon (C): 0.42%, silicon (Si): 0.27%, manganese (Mn): 0.67%, sulfur (S): ≤0.015%, phosphorus (P): ≤0.015%, chromium (Cr): 1.05%, molybdenum (Mo): 0.20%, vanadium (V): 0.05%, niobium (Nb): 0.03%, boron (B): 0.002%, RE (composite rare earth): 0.01%, nickel (Ni): 0.35%, copper (Cu): 0.20%, tungsten (W): 0.03%, with the remainder being iron and unavoidable impurities.

[0013] Furthermore, a high-strength, high-toughness, high-strain-rate impact-resistant bar material, wherein the chemical composition of the high-strength, high-toughness, high-strain-rate impact-resistant bar has a Cr / Mo mass percentage ratio in the range of (4.5~6.5):1.

[0014] By introducing rare earth microalloying, the sulfides are transformed from type II MnS into spherical RE-SO composite inclusions, reducing their aspect ratio from the conventional 8:1 to 2:1, significantly improving impact toughness. Simultaneously, the phosphorus grain boundary segregation problem is solved through a two-stage mist cooling process, reducing the grain boundary P concentration to less than 1.3 times that of the matrix. A Cr / Mo ratio within the range of (4.5–6.5):1 significantly improves the material's corrosion resistance and creep resistance. Furthermore, a method for preparing a high-strength, high-toughness, high-strain-rate impact-resistant bar material includes the following steps:

[0015] (1) Homogenization treatment: The high-strength and tough special alloy ingot is homogenized;

[0016] (2) Extrusion molding: The homogenized ingot is extruded to obtain a bar;

[0017] (3) Austenitizing treatment: Heat the bar to the austenitizing temperature range to make the structure completely austenitized. Then, perform oil cooling treatment on the austenitized bar to quickly cool it to the salt bath distribution temperature.

[0018] (4) Salt bath fractionation: Salt bath fractionation is performed on the austenitized bars to precisely control the tempering temperature and time, and adjust their hardness and toughness.

[0019] (5) Induction hardening: The bar material after salt bath treatment is subjected to induction heating tempering treatment to accurately control the distribution temperature and time and adjust the microstructure.

[0020] (6) Tempering treatment: Tempering treatment is performed on the bars after induction hardening.

[0021] Furthermore, a method for preparing a high-strength, high-toughness, high-strain-rate impact-resistant bar material includes the following steps:

[0022] (1) Homogenization treatment: The high-strength and tough special alloy ingot is heated to 1050-1250℃ for homogenization treatment and held for 2.0-8.0h;

[0023] (2) Extrusion molding: The homogenized ingot is extruded once, with the starting extrusion temperature being 1000-1100℃ and the ending extrusion temperature being not lower than 950℃, to obtain a bar; the bar after the first extrusion is subjected to mist cooling treatment; the ingot after the first mist cooling treatment is extruded a second time, with the starting extrusion temperature being 750-900℃ and the ending extrusion temperature being not lower than 700℃; the bar after the second extrusion is subjected to a second mist cooling treatment.

[0024] (3) Austenitizing treatment: The austenitizing temperature range is 850–950℃, and the holding time is [missing information].

[0025] 1.0~2.0h.

[0026] (4) Salt bath preparation: The temperature of the salt bath preparation is 200–300℃, and the holding time is 10.0–30.0 seconds.

[0027] min.

[0028] (5) Induction hardening: The induction heating hardening process includes at least one heating cycle, the temperature and time of each heating cycle are independently adjustable, the heating temperature range is 850~950℃, and the total time is 10~30min.

[0029] (6) Tempering treatment: Temper the induction hardened bar at a temperature of 500-650℃ for 1.0-3.0h.

[0030] Furthermore, in a method for preparing a high-strength, high-toughness, high-strain-rate impact-resistant rod material, step (2) involves a primary extrusion temperature of 1000–1100℃, a compression ratio controlled between 4.0 and 6.0, an extrusion speed controlled between 0.5 and 2.0 m / min, and a primary mist cooling rate controlled between 10 and 20℃ / s. The secondary extrusion temperature is 800–900℃, a compression ratio controlled between 2.0 and 4.0, an extrusion speed controlled between 0.3 and 0.4 m / min, and a secondary mist cooling rate controlled between 10 ± 5℃ / s.

[0031] Furthermore, a method for preparing a high-strength, high-toughness, high-strain-rate impact-resistant rod material is provided, wherein the mist cooling is performed using a multi-mode controlled mist cooling device to achieve a precise cooling process. The spray angle between the atomizing nozzle and the rod is 45°, and the atomized liquid sprayed from the nozzle covers 1 / 4 of the outer circumference of the rod, with the diameter of the atomized droplets controlled between 20 and 40 μm.

[0032] Furthermore, a method for preparing a high-strength, high-toughness, high-strain-rate impact-resistant rod material is provided, wherein the induction heating quenching includes two heating cycles. The first stage is high-frequency rapid heating, with a frequency of 10-50 kHz to rapidly heat the rod and form an ultra-fine crystalline strengthening layer on the surface. When the surface temperature of the rod reaches the induction quenching set value, the method switches to medium-frequency induction heating, with a frequency of 1-10 kHz to perform through-heating treatment on the core of the rod and optimize the core toughness.

[0033] Furthermore, a method for preparing a high-strength, high-toughness, high-strain-rate impact-resistant rod material is provided, wherein the alloy rod, after being extruded, has an ultrafine-grained structure with a grain size of 1.0–5.0 μm, no macroscopic structural defects, and a surface finish Ra ≤ 0.8.

[0034] Furthermore, a method for preparing a high-strength, high-toughness, high-strain-rate impact-resistant rod material is provided, wherein the special alloy rod, after undergoing the heat treatment process, has a tensile strength of over 2000 MPa and a yield strength of over 1800 MPa.

[0035] This invention, through innovative compositional system and multi-stage process synergy, constructs a multi-scale composite microstructure with gradient characteristics, breaking through the technical bottleneck of traditional materials that struggle to simultaneously achieve strength and toughness. Based on the large deformation extrusion and dynamic recrystallization mechanism, it induces the formation of ultrafine equiaxed grains in a high dislocation density matrix, and through rapid cooling to control phase transformation kinetics, it retains substructures (dislocation cells, small-angle grain boundaries) within the grains to maintain work hardening capability. It innovatively employs a salt bath partitioning and induction hardening composite process to construct a gradient distribution of retained austenite and nanoscale carbides in the material, forming a multi-phase synergistic system of "hard phase encapsulating tough phase." Through rare earth microalloying and precise mist cooling technology, it achieves sulfide morphology control and grain boundary segregation suppression. Combined with the pinning effect of ultrafine lamellar structure and multi-scale precipitates, it significantly improves crack propagation resistance. This invention enables materials to achieve strengths exceeding 2000 MPa while also possessing excellent low-temperature toughness and impact resistance. Its multi-scale microstructure control strategy provides a new paradigm for the development of strong and tough materials under high strain rate conditions.

[0036] Furthermore, a method for preparing a high-strength, high-toughness, high-strain-rate impact-resistant rod material is provided, wherein the special alloy rod, after undergoing the heat treatment process, exhibits good low-temperature impact toughness, with an impact energy of not less than 40J at -40℃.

[0037] Furthermore, the impact-resistant rod material is used in structural components requiring high strength and high toughness, such as spacecraft landing buffer struts, large forged hammer head connecting shafts, and shield machine cutterhead impact seats.

[0038] Compared with the prior art, the present invention has the following advantages:

[0039] 1. Significant cost advantage: By relaxing the restrictions on sulfur and phosphorus impurities and optimizing the element ratio, the raw material requirements and production costs are reduced, achieving high cost performance while ensuring ultra-high strength (≥2000MPa), making it suitable for large-scale manufacturing.

[0040] 2. Simple and efficient process: The innovative combination of two-stage extrusion and precise mist cooling process simplifies the traditional complex process. The controllable heating-cooling cycle achieves finer texture, making the operation convenient and the yield high.

[0041] 3. Stable and reliable performance: The material has both ultra-high strength and excellent toughness, and maintains stable performance under complex working conditions such as high-speed impact and extreme low temperature, with outstanding fatigue resistance. Attached Figure Description

[0042] Figure 1 A process flow diagram of the preparation method of the present invention is shown;

[0043] Figure 2 The heat treatment process diagram of Example 1 is shown;

[0044] Figure 3 The tissue EBSD image of Example 1 is shown;

[0045] Figure 4 The heat treatment process diagram of Example 2 is shown;

[0046] Figure 5 An EBSD photograph of the tissue from Example 2 is shown. Detailed Implementation

[0047] The present invention will now be described in detail with reference to the accompanying drawings and specific embodiments. It should be noted that those skilled in the art can make various changes and modifications without departing from the concept of the present invention. These all fall within the scope of protection of the present invention.

[0048] The present invention will now be described in detail with reference to the accompanying drawings and specific embodiments. It should be noted that those skilled in the art can make various changes and modifications without departing from the concept of the present invention. These all fall within the scope of protection of the present invention.

[0049] Example 1

[0050] This embodiment discloses a high-strength, high-toughness, high-strain-rate impact-resistant bar material, its manufacturing method, and its application. The chemical composition of the material is as follows: carbon (C): 0.38%, silicon (Si): 0.17%, manganese (Mn): 0.50%, sulfur (S): 0.02%, phosphorus (P): 0.025%, chromium (Cr): 0.90%, molybdenum (Mo): 0.15%, vanadium (V): 0.02%, niobium (Nb): 0.01%, boron (B): 0.0005%, with the remainder being iron and unavoidable impurities. The specific process steps are as follows:

[0051] 1. Homogenization treatment: Heat the high-strength and tough special alloy ingot to 1100℃ and hold for 3.0h.

[0052] 2. One-time extrusion molding: The homogenized ingot is extruded once at an initial extrusion temperature of 1050℃ and an end temperature of 960℃, with the compression ratio controlled at 4.5 and the extrusion speed at 1.0m / min, thereby obtaining a pre-formed bar.

[0053] 3. First-stage mist cooling treatment: The bar after the first extrusion is subjected to mist cooling treatment, and the cooling rate is controlled at 15℃ / s; the spray angle between the atomizing nozzle and the bar is 45°, and the atomized liquid sprayed by the nozzle only covers 1 / 4 of the outer circumference of the bar, and the diameter of the atomized droplets is controlled at 25μm.

[0054] 4. Secondary extrusion molding: The ingot that has undergone the first mist cooling treatment is subjected to secondary extrusion. The initial extrusion temperature is controlled at 800℃, the final temperature is 700℃, the compression ratio is controlled at 2.5, and the extrusion speed is controlled at 0.35m / min.

[0055] 5. Secondary mist cooling treatment: The bar after secondary extrusion is subjected to secondary mist cooling treatment, and the cooling rate is controlled at 10℃ / s.

[0056] 6. Austenitizing treatment: The bar after secondary extrusion is heated to the austenitizing temperature range of 900℃ and held for 1.5 hours to fully austenitize the microstructure.

[0057] 7. Salt bath preparation: The quenched bar is immediately immersed in a salt bath at 250℃ and held for 20.0 min to regulate the microstructure and effectively reduce internal stress.

[0058] 8. Induction heating quenching: The bar stock after salt bath treatment is subjected to induction heating quenching treatment. The tempering process includes at least one heating cycle. The temperature and holding time of each heating cycle can be adjusted independently. The tempering temperature is 850℃ and the holding time is 10.0min, thereby precisely adjusting the hardness and toughness of the material.

[0059] 9. Tempering treatment: Temper the bars after induction heating quenching at a temperature of 500℃ for 1.5 hours.

[0060] 10. Air cooling: The tempered bars are air cooled to room temperature to obtain the desired mechanical properties.

[0061] The high-strength, high-toughness, high-strain-rate impact-resistant rod material, after undergoing the aforementioned heat treatment process, exhibits an ultrafine-grained microstructure with grain size controlled within 1.5 μm, free of macroscopic structural defects, and a surface finish Ra ≤ 0.8. In terms of mechanical properties, the alloy rod demonstrates a tensile strength of 2100 MPa and a yield strength exceeding 1900 MPa; furthermore, it exhibits excellent low-temperature impact toughness at -40℃, with an impact energy of 42 J.

[0062] The carbon (C) content is controlled at 0.38–0.45%, serving as a core element for matrix strengthening. Carbon forms (Fe,Cr,Mo)3C-type composite carbides with chromium and molybdenum, achieving a dynamic balance between solid solution strengthening and second-phase strengthening. However, when the carbon content exceeds 0.45%, the segregation of chromium-rich carbides at grain boundaries intensifies, leading to a decrease in impact toughness. The silicon (Si) content is controlled at 0.17–0.37%, which helps with deoxidation and increases strength, while also improving the steel's corrosion resistance. The manganese (Mn) content is controlled at 0.50–0.80%, which improves the hardness and strength of the steel, while also helping with desulfurization and improving the steel's hot working properties. Other high-performance special alloy products often limit sulfur (S) and phosphorus (P) content to ≤0.005%. The material proposed in this invention… The preparation method of this material has a wider range of requirements for sulfur (S) and phosphorus (P) in raw materials (≤0.035%), which broadens the selection range of raw materials and reduces production costs. Controlling the chromium (Cr) content at 0.90-1.20% can improve the hardness, strength, and corrosion resistance of steel. Controlling the molybdenum (Mo) content at 0.15-0.25% can improve the strength of steel and enhance its resistance to high-temperature creep. Controlling the vanadium (V) and niobium (Nb) content at 0.02-0.08% and 0.01-0.05% respectively can refine the grains of steel, improve strength and toughness, and form carbides to improve the wear resistance of steel. Controlling the boron (B) content at 0.0005-0.003% can improve the hardenability of steel and also improve its hardness and wear resistance.

[0063] Examples 2-9

[0064] For the specific components, processes, and properties in the embodiments, please refer to Tables 1, 2, 3, and 4.

[0065] The impact-resistant rod materials described in Examples 1-9 are used in structural components requiring high strength and high toughness, such as spacecraft landing buffer struts, large forged hammer head connecting shafts, and shield machine cutterhead impact seats.

[0066] Table 1. Components in each embodiment

[0067] Group Carbon (C) Silicon (Si) Manganese (Mn) Sulfur (S) Phosphorus (P) Chromium (Cr) Molybdenum (Mo) Vanadium (V) Niobium (Nb) Boron (B) Composite rare earth (RE) Nickel (Ni) Copper (Cu) Tungsten (W) Example 1 0.38 0.17 0.5 0.02 0.025 0.9 0.15 0.02 0.010 0.0005 0.001 0.35 0.2 0.03 Example 2 0.42 0.2 0.6 0.03 0.03 1.0 0.18 0.04 0.030 0.0010 0.005 0.33 0.18 0.02 Example 3 0.44 0.35 0.75 0.015 0.01 1.15 0.22 0.07 0.040 0.0025 0.002 0.37 0.22 0.04 Example 4 0.40 0.3 0.65 0.025 0.035 1.1 0.20 0.05 0.050 0.0030 0.010 0.35 0.20 0.03 Example 5 0.42 0.27 0.67 0.010 0.005 1.05 0.20 0.05 0.030 0.0020 0.015 0.34 0.21 0.05 Example 6 0.41 0.25 0.55 0.033 0.02 0.95 0.16 0.03 0.015 0.0007 0.020 0.35 0.2 0.01 Example 7 0.43 0.28 0.7 0.027 0.032 1.05 0.19 0.06 0.020 0.0020 0.013 0.35 0.23 0.03 Example 8 0.39 0.19 0.52 0.022 0.015 0.92 0.17 0.03 0.012 0.0012 0.008 0.38 0.17 0.02 Example 9 0.44 0.33 0.78 0.035 0.035 1.18 0.24 0.08 0.045 0.0028 0.009 0.32 0.24 0.04

[0068] Table 2 shows the process of one extrusion in each embodiment.

[0069]

[0070] Table 3 shows the secondary extrusion process in each embodiment.

[0071]

[0072] Example Grain size (μm) Tensile strength (MPa) Yield strength (MPa) Impact energy (J) Example 1 1.5 2080 1800 47 Example 2 25 2180 1950 45 Example 3 1.2 2050 1850 45 Example 4 45 2250 2050 40 Example 5 20 2140 1880 44 Example 6 32 2144 1950 45 Example 7 1.8 2100 1820 50 Example 8 38 2110 1980 44 Example 9 1.0 2000 1800 52

[0073] Table 4 Performance parameters of each embodiment

[0074] Although embodiments of the invention have been shown and described, it will be understood by those skilled in the art that various changes, modifications, substitutions and alterations can be made to these embodiments without departing from the principles and spirit of the invention, the scope of which is defined by the appended claims and their equivalents.

Claims

1. A high-strength, high-toughness, high-strain-rate impact-resistant rod material, characterized in that, The chemical composition of the high-strength, high-toughness, high-strain-rate impact-resistant rod includes carbon (C): 0.38~0.45%, silicon (Si): 0.17~0.37%, manganese (Mn): 0.50~0.80%, sulfur (S): ≤0.035%, phosphorus (P): ≤0.035%, chromium (Cr): 0.90~1.20%, and molybdenum (Mo): The chemical composition of the high-strength, high-toughness, high-strain-rate impact-resistant rod is as follows: 0.15~0.25%, Vanadium (V): 0.02~0.08%, Niobium (Nb): 0.01~0.05%, Boron (B): 0.0005~0.003%, Composite Rare Earth (RE): 0.001~0.02%, Nickel (Ni): 0.20~0.50%, Copper (Cu): 0.10~0.30%, Tungsten (W): 0.01~0.05%, with the remainder being iron and unavoidable impurities; the Cr / Mo mass percentage ratio of the rod is in the range of (4.5~6.5):1; its tensile strength reaches above 2000MPa, and its yield strength reaches above 1800MPa; it has good low-temperature impact toughness, and its impact energy at -40℃ is not less than 40 J.

2. The high-strength, high-toughness, high-strain-rate impact-resistant rod material according to claim 1, characterized in that, The chemical composition of the high-strength, high-toughness, high-strain-rate impact-resistant rod includes carbon (C): 0.40~0.43%, silicon (Si): 0.20~0.35%, manganese (Mn): 0.60~0.75%, sulfur (S): ≤0.015%, phosphorus (P): ≤0.015%, chromium (Cr): 0.90~1.20%, molybdenum (Mo): 0.15~0.25%, vanadium (V): 0.02~0.08%, niobium (Nb): 0.01~0.05%, boron (B): 0.0005~0.003%, composite rare earth RE: 0.001~0.02%, nickel (Ni): 0.20~0.50%, copper (Cu): 0.10~0.30%, tungsten (W): 0.01~0.05%, with the remainder being iron and unavoidable impurities.

3. The high-strength, high-toughness, high-strain-rate impact-resistant rod material according to claim 1, characterized in that, The chemical composition of the high-strength, high-toughness, high-strain-rate impact-resistant bar includes carbon (C): 0.42%, silicon (Si): 0.27%, manganese (Mn): 0.67%, sulfur (S): ≤0.015%, phosphorus (P): ≤0.015%, chromium (Cr): 1.05%, molybdenum (Mo): 0.20%, vanadium (V): 0.05%, niobium (Nb): 0.03%, boron (B): 0.002%, composite rare earth RE: 0.01%, nickel (Ni): 0.35%, copper (Cu): 0.20%, tungsten (W): 0.03%, with the remainder being iron and unavoidable impurities.

4. A method for preparing a high-strength, high-toughness, high-strain-rate impact-resistant rod material as described in any one of claims 1-3, characterized in that, Includes the following steps: (1) Homogenization treatment: The high-strength and high-toughness special alloy ingot is heated to 1050~1250℃ for homogenization treatment and held for 2.0~8.0 h; (2) Extrusion molding: The homogenized ingot is extruded once, with the starting extrusion temperature at 1000~1100℃ and the ending extrusion temperature at no less than 950℃ to obtain a bar; the bar after the first extrusion is subjected to mist cooling treatment; the ingot after the first mist cooling treatment is extruded a second time, with the starting extrusion temperature at 750~900℃ and the ending extrusion temperature at no less than 700℃; the bar after the second extrusion is subjected to a second mist cooling treatment. Obtain bar stock; (3) Austenitizing treatment: The bar is heated to the austenitizing temperature range to make the structure completely austenitized, and the austenitized bar is subjected to oil cooling treatment to rapidly cool to the salt bath distribution temperature; the austenitizing temperature range is 850~950℃, and the holding time is 1.0~2.0 h; (4) Salt bath fractionation: The austenitized bar is subjected to salt bath fractionation treatment to precisely control the fractionation temperature and time, and adjust its hardness and toughness; the salt bath fractionation temperature is 200~300℃, and the holding time is 10.0~30.0 min; (5) Induction hardening: The bar material after salt bath treatment is subjected to induction heating hardening treatment to accurately control the distribution temperature and time and adjust the microstructure; the induction heating hardening treatment includes at least one heating cycle, the temperature and time of each heating cycle are independently adjustable, the heating temperature range is 850~950℃, and the total time is 10~30 min. (6) Tempering treatment: Temper the induction hardened bar at a temperature of 500~650℃ for 1.0~3.0 h.

5. The method for preparing a high-strength, high-toughness, high-strain-rate impact-resistant rod material according to claim 4, characterized in that, In step (2), the primary extrusion temperature is 1000~1100℃, the compression ratio is controlled between 4.0 and 6.0, the extrusion speed is controlled between 0.5 and 2.0 m / min, and the cooling rate of the primary mist cooling is controlled between 10 and 20 ℃ / s. The secondary extrusion temperature is 800~900℃, the compression ratio is controlled between 2.0 and 4.0, the extrusion speed is controlled between 0.3 and 0.4 m / min, and the cooling rate of the secondary mist cooling is controlled between 10±5 ℃ / s.

6. The method for preparing a high-strength, high-toughness, high-strain-rate impact-resistant bar material according to claim 4, characterized in that, The mist cooling is carried out using a multi-mode controlled mist cooling device to achieve a precise cooling process; the spray angle between the atomizing nozzle and the rod is 45°, and the atomized liquid sprayed from the nozzle covers 1 / 4 of the outer circumference of the rod, with the diameter of the atomized droplets controlled between 20 and 40 μm.

7. The method for preparing a high-strength, high-toughness, high-strain-rate impact-resistant rod material according to claim 4, characterized in that, The induction heating quenching includes two heating cycles. The first stage is high-frequency rapid heating, with a frequency of 10~50 kHz to rapidly heat up the bar. When the surface temperature of the bar reaches the induction quenching set value, it switches to medium-frequency induction heating, with a frequency of 1~10 kHz to perform through-heating treatment on the core of the bar.

8. The method for preparing a high-strength, high-toughness, high-strain-rate impact-resistant bar material according to claim 4, characterized in that, The alloy rod, after being extruded, has an ultrafine grain structure with a grain size of 1.0~5.0μm and no macroscopic structural defects, and a surface finish Ra≤0.

8.

9. The method for preparing a high-strength, high-toughness, high-strain-rate impact-resistant bar material according to claim 4, characterized in that, Its tensile strength reaches over 2000MPa and its yield strength reaches over 1800MPa.

10. The method for preparing a high-strength, high-toughness, high-strain-rate impact-resistant bar material according to claim 4, characterized in that, It has good low-temperature impact toughness, and its impact energy at -40℃ is not less than 40 J.

11. The application of a high-strength, high-toughness, high-strain-rate impact-resistant bar material according to any one of claims 1-3, characterized in that, The impact-resistant rod material is used in structural components requiring high strength and high toughness, such as spacecraft landing buffer struts, large forged hammer head connecting shafts, and shield machine cutterhead impact seats.

Images