A high-strength bar and its preparation method

Abstract

This invention discloses a high-strength bar stock, relating to the field of high-strength bar stock technology. This invention achieves its goal by precisely adjusting the alloy composition: carbon (C) 0.3-0.35%, silicon (Si) 0.90-1.10%, manganese (Mn) 2.10-2.30%, titanium (Ti) 0.25-0.35%, phosphorus (P) ≤0.02%, sulfur (S) ≤0.02%, chromium (Cr) 0.48-0.55%, vanadium (V) 0.04-0.06%, with the remainder being iron and unavoidable impurities. By precisely controlling the content of alloying elements, particularly increasing the content of strengthening elements such as carbon, silicon, and manganese to the optimal range, and supplementing with the synergistic effect of alloying elements such as titanium, vanadium, and chromium, the strength and yield strength of the material are improved, while maintaining or enhancing its toughness. This results in an ultimate performance with a tensile strength ≥1050 MPa and a yield strength ≥820 MPa. This strength level not only far exceeds that of traditional bar stock, but also sets a new benchmark in the field of high-end manufacturing, providing a solid material foundation for building more robust and durable products.

Description

Technical Field

[0001] This invention relates to the field of high-strength bar technology, specifically to a high-strength bar and its preparation method. Background Technology

[0002] Driven by the rapid advancements in modern industrial technology, the performance requirements for metallic materials are increasing at an unprecedented rate, especially under extreme working environments (such as high temperature and high pressure), which place even more stringent demands on the comprehensive properties of materials, including strength and toughness. While traditional metallic materials have a wide range of applications in various industrial sectors, their performance bottlenecks become increasingly apparent when faced with these extreme conditions, making it difficult to meet the demands of modern industry for high-performance materials. High-strength, high-yield-strength bars, as a class of special metallic materials, are widely used in key areas such as construction, bridges, automobiles, aerospace, marine engineering, and petrochemicals due to their superior mechanical properties. This technological field focuses on developing new bars with high tensile strength, high yield strength, good elongation, suitable hardness, and excellent impact toughness to meet the extremely stringent performance requirements of industrial applications.

[0003] Most high-strength bars currently on the market rely on complex alloying designs and cumbersome heat treatment processes. This not only increases production costs but may also introduce new problems during material processing and use, such as cracking and brittle fracture, severely affecting the yield and reliability of the material. Furthermore, because high strength and toughness are often mutually restrictive, and improving corrosion resistance requires specific alloying elements and refined manufacturing processes, existing high-strength bars often struggle to simultaneously achieve good toughness and corrosion resistance while pursuing high strength and high yield strength. Therefore, how to further improve the toughness and corrosion resistance of materials while ensuring high strength and yield strength has become a pressing technical challenge in the field of materials science. To address this, this invention proposes a new type of high-strength bar. Summary of the Invention

[0004] (a) Technical problems to be solved

[0005] To address the urgent need in modern industry for high strength and high toughness of metallic materials under extreme working conditions, this invention provides a high-strength bar and its preparation method. By precisely controlling the alloy composition and optimizing the heat treatment process, a high-strength bar with excellent comprehensive performance has been successfully developed, providing a new material solution for high-end manufacturing. This solves the problem that most high-strength bars on the market rely on complex alloying designs and cumbersome heat treatment processes, which not only increase production costs but may also introduce new problems during material processing and use, such as cracks and brittle fracture, seriously affecting the yield and reliability of the material. Furthermore, existing high-strength bars, while pursuing high strength and high yield strength, often struggle to simultaneously achieve good toughness and corrosion resistance.

[0006] (II) Technical Solution

[0007] The purpose of this invention is to provide a high-strength bar to solve the problems mentioned in the background art.

[0008] To achieve the above objectives, the present invention provides the following technical solution: a high-strength bar material comprising the following chemical composition by weight percentage: carbon (C) 0.3-0.35%, silicon (Si) 0.90-1.10%, manganese (Mn) 2.10-2.30%, titanium (Ti) 0.25-0.35%, phosphorus (P) ≤0.02%, sulfur (S) ≤0.02%, chromium (Cr) 0.48-0.55%, vanadium (V) 0.04-0.06%, with the remainder being iron and unavoidable impurities.

[0009] Through the above technical solution, addressing the application requirements in harsh working environments, this application's technical solution specifically adds an appropriate amount of chromium and strictly controls the content of harmful elements such as phosphorus and sulfur, thereby significantly improving the material's corrosion resistance. This improvement enables the high-strength bar to maintain good performance even in harsh environments such as humidity and corrosion, broadening the material's application range and providing a reliable material choice for more fields. Furthermore, although the high-strength bar of this invention achieves a significant performance improvement, its alloy composition is rationally designed and does not use a large amount of expensive rare elements, thus offering a certain cost advantage.

[0010] A method for preparing high-strength bars, the method following a standard process, includes raw material preparation, batching according to chemical composition ratios, smelting, hot rolling, heat treatment, and subsequent processing steps to obtain the high-strength bars. The heat treatment process includes the following specific steps:

[0011] Step 1: First, heat the bar stock to 860-880℃ for austenitization treatment, and then air cool it to room temperature;

[0012] Step 2: Then heat the bar to 560-580℃ for tempering.

[0013] Through the above technical solution, the optimized heat treatment process results in a uniform and fine internal structure of the material, thereby reducing the occurrence of cracks and deformation during processing and improving processing efficiency and yield. This characteristic reduces production costs, improves production efficiency, and provides strong support for large-scale applications. The high-strength bars of this invention not only have excellent performance but also good machinability.

[0014] Preferably, the performance indicators of the high-strength bar obtained after heat treatment include: tensile strength not less than 1050 MPa, yield strength not less than 820 MPa, elongation not less than 16.5%, hardness in the range of 380-420 HB, and room temperature V-notch impact energy not less than 30 J.

[0015] Preferably, the amount of each element added is strictly controlled during the smelting process to ensure that the chemical composition meets the specified ratio.

[0016] Preferably, the subsequent processing steps include forging, rolling, etc., to adjust the shape and size of the bar.

[0017] Preferably, the austenitizing temperature and tempering temperature in the heat treatment step need to be precisely controlled to ensure that the bar obtains the required mechanical properties and yield strength, and the final high-strength bar needs to undergo rigorous performance testing to ensure that it meets the specified performance indicators.

[0018] (III) Beneficial Effects

[0019] This invention provides a high-strength bar stock. Compared with the prior art, the advantages of this invention are:

[0020] 1. This invention proposes a novel high-strength bar stock. By precisely adjusting the alloy composition—C 0.3-0.35%, Silicon (Si) 0.90-1.10%, Manganese (Mn) 2.10-2.30%, Titanium (Ti) 0.25-0.35%, Phosphorus (P) ≤0.02%, Sulfur (S) ≤0.02%, Chromium (Cr) 0.48-0.55%, Vanadium (V) 0.04-0.06%, with the remainder being iron and unavoidable impurities—the invention achieves superior performance. This is achieved by precisely controlling the content of alloying elements, particularly increasing the content of reinforcing elements such as carbon, silicon, and manganese to their optimal range, and supplementing this with the synergistic effect of alloying elements such as titanium, vanadium, and chromium. This improves the material's strength and yield strength while maintaining or enhancing its toughness, resulting in an ultimate tensile strength ≥1050 MPa and a yield strength ≥820 MPa. This strength level not only far exceeds that of traditional bars but also sets a new benchmark in high-end manufacturing, providing a solid material foundation for building more robust and durable products.

[0021] 2. This invention proposes a novel high-strength bar stock. Through an optimized heat treatment process (austenitization at 860-880℃ followed by air cooling and tempering at 560-580℃), and by refining the grain size and eliminating internal stress, it achieves high strength without neglecting the material's toughness requirements. Through optimized heat treatment processes and a reasonable alloy composition, the material achieves an elongation of ≥16.5%, exhibiting excellent toughness. This characteristic ensures that the material maintains structural integrity and stability under complex stress or impact, effectively extending product lifespan and improving safety during use, further enhancing the material's overall performance. A good balance is achieved between high strength and high yield strength, as well as toughness and corrosion resistance, providing a more reliable material choice for applications under extreme conditions. This gives the material broader application prospects and higher market competitiveness in high-end manufacturing, injecting new vitality into the industry's development. Attached Figure Description

[0022] Figure 1 This is a process flow diagram of the heat treatment process provided in an embodiment of the present invention. Detailed Implementation

[0023] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0024] Please see Figure 1 The present invention provides a high-strength bar stock comprising the following chemical composition by weight percentage: carbon (C) 0.3-0.35%, silicon (Si) 0.90-1.10%, manganese (Mn) 2.10-2.30%, titanium (Ti) 0.25-0.35%, phosphorus (P) ≤0.02%, sulfur (S) ≤0.02%, chromium (Cr) 0.48-0.55%, vanadium (V) 0.04-0.06%, with the remainder being iron and unavoidable impurities.

[0025] The high-strength bar of this invention has a carefully designed and formulated alloy composition aimed at achieving comprehensive optimization of material properties. Specifically:

[0026] Carbon (C): As a key strengthening element, its content plays a decisive role in the microstructure and mechanical properties of materials. An appropriate amount of carbon content significantly improves the hardness and strength of materials, laying a solid foundation for the high yield strength of materials. The carbon content was finally determined to be 0.3-0.35%.

[0027] Silicon (Si): As a good deoxidizer, it can exist in ferrite or austenite in solid solution form. The addition of silicon not only helps to refine the grains and improve the toughness of the material, but also enhances its corrosion resistance, enabling the material to perform well in a variety of environments. The silicon content was finally determined to be 0.90-1.10%.

[0028] Manganese (Mn): As a solid solution strengthening element, manganese can be dissolved in the iron matrix to play a role in solid solution strengthening, stabilize ferrite, improve the strength and hardness of steel, while maintaining good toughness, and improve the microstructure of steel. It has a significant effect on improving the yield strength and tensile strength of materials, further enhancing the load-bearing capacity of materials. Moreover, manganese can promote the formation of austenite in heat treatment and improve the hardenability of steel. In the tempering process, manganese helps to inhibit the precipitation of carbides and maintain the stability of ferrite. The content of manganese was finally determined to be 2.10-2.30%.

[0029] Titanium (Ti): Titanium is a powerful grain-refining element. The addition of titanium refines the grain structure by forming stable compounds, effectively inhibiting grain growth in steel during heating, thus obtaining a fine grain structure. This significantly improves the strength, toughness, and plasticity of the material, thereby enhancing its mechanical properties. Simultaneously, titanium forms stable carbides with carbon, which act as dispersion strengthening agents in steel, increasing its strength and hardness. Furthermore, titanium carbides are less prone to aggregation and coarsening during tempering, improving the tempering stability of the steel. The addition of titanium also improves the corrosion resistance of the material, especially in chlorine-containing environments. The final titanium content was determined to be 0.25-0.35%.

[0030] Phosphorus (P) and sulfur (S) should both be less than or equal to 0.02%. Both phosphorus and sulfur are harmful elements in steel. Phosphorus tends to segregate at the grain boundaries of steel, leading to increased cold brittleness, i.e., decreased impact toughness at low temperatures. Sulfur readily combines with iron in steel to form iron sulfide (FeS). This compound melts at high temperatures, causing cracks in the steel during hot working, i.e., hot brittleness. The presence of both reduces the strength, plasticity, and toughness of steel. Strictly controlling the content of these harmful elements effectively reduces internal defects in the material and improves overall performance.

[0031] Chromium (Cr): Chromium is a ferrite stabilizing element. Chromium can also improve the strength and hardness of steel. It can be infinitely dissolved in iron. When combined with Mn and Si elements, it can enhance solid solution strengthening. The addition of chromium significantly enhances the corrosion resistance of materials, especially in oxidizing and corrosive environments, which can protect materials from corrosion and extend their service life. The final chromium content was determined to be 0.45-0.55%.

[0032] Vanadium (V): As a microalloying element, vanadium is a strong carbide-forming element that can form fine and uniformly distributed vanadium carbides in steel. Vanadium carbides have high hardness, which can improve the wear resistance of materials and is suitable for manufacturing wear-resistant parts. Furthermore, vanadium can prevent grain growth during heating through grain refinement and precipitation strengthening mechanisms, thereby obtaining a fine-grained structure, improving the strength and toughness of materials, and achieving performance optimization. The vanadium content was finally determined to be 0.04-0.06%.

[0033] Based on the chemical composition of the raw materials by weight percentage, this application also provides a method for preparing high-strength bars. The preparation method follows a standard process, including raw material preparation, batching according to the chemical composition ratio, and obtaining high-strength bars through smelting, hot rolling, heat treatment, and subsequent processing steps. Furthermore, the preparation process may also include purification treatment steps such as degassing and slag removal to improve the purity and quality of the bars. For example, through refining and degassing processes, the phosphorus and sulfur content in the steel can be effectively reduced, thereby improving the quality and performance of the steel.

[0034] To fully utilize the potential of the alloy composition, the heat treatment process includes the following specific steps:

[0035] Step 1: First, heat the bar to 860-880℃ for austenitization treatment to fully austenitize the material. This step aims to eliminate internal structural defects and create favorable conditions for subsequent phase transformation and strengthening processes. Then, air cool to room temperature. After austenitization, rapid cooling by air cooling is used to suppress grain growth and retain the supersaturated solid solution in the austenite, providing the necessary conditions for subsequent precipitation strengthening and grain refinement.

[0036] Step two: The bar stock is then heated to 560-580℃ for tempering to eliminate quenching stress, stabilize the microstructure, and promote the formation of precipitates. Tempering not only improves the strength and toughness of the material but also ensures stable performance during use.

[0037] Through the above-mentioned alloy composition design and heat treatment process optimization, the high-strength bar of the present invention exhibits excellent performance indicators: tensile strength ≥1050 MPa, which is far higher than that of traditional materials, ensuring the stability and safety of the material under extreme loads.

[0038] With a yield strength ≥820 MPa, the material possesses strong load-bearing capacity and resistance to deformation.

[0039] With an elongation of ≥16.5%, the material is given good plastic deformation ability while ensuring high strength, which improves safety during processing and use.

[0040] With a hardness of 380-420HB, this moderate hardness range meets the needs of various application scenarios, ensuring the wide applicability of the material.

[0041] The impact energy of a V-notch at room temperature is ≥30J, indicating that the material has good impact resistance and can maintain stable performance under harsh working conditions.

[0042] In summary, the high-strength bar of this invention achieves a perfect combination of high strength, high toughness, good corrosion resistance, and cost-effectiveness through innovative alloy composition design and optimized heat treatment process, providing a high-performance and cost-effective new material option for high-end manufacturing.

[0043] Example 1

[0044] In this embodiment, a high-strength bar with a specification of Ф10mm×3000mm was prepared. The specific chemical composition is as follows (by weight percentage): (C) 0.301%, silicon (Si) 0.95%, manganese (Mn) 2.12%, titanium (Ti) 0.28%, phosphorus (P) ≤0.02%, sulfur (S) ≤0.02%, chromium (Cr) 0.55%, vanadium (V) 0.05%, with the remainder being iron and unavoidable impurities.

[0045] The preparation process follows a standard procedure, including raw material preparation, batching according to chemical composition ratio, smelting, hot rolling, and austenitization at 875℃ followed by air cooling, and then tempering at 575℃.

[0046] The final product's performance test results show that the tensile strength reaches 1055 MPa, the yield strength is 827 MPa, the elongation is 18.5%, the hardness is 382 HB, and the room temperature V-notch impact energy is 35 J, which fully meets and exceeds the specified performance indicators.

[0047] Example 2

[0048] This embodiment describes the preparation of a high-strength bar with a specification of Ф10mm×2500mm. Its chemical composition is adjusted (by weight percentage): (C) 0.31%, silicon (Si) 1.01%, manganese (Mn) 2.20%, titanium (Ti) 0.30%, phosphorus (P) ≤0.02%, sulfur (S) ≤0.02%, chromium (Cr) 0.54%, vanadium (V) 0.048%, with the remainder being iron and unavoidable impurities.

[0049] The same preparation process as in Example 1 was used. The preparation process followed the standard procedure, including raw material preparation, batching according to the chemical composition ratio, melting, hot rolling, and austenitization at 875°C followed by air cooling, and then tempering at 575°C. However, special attention was paid to temperature control during the heat treatment process to ensure the uniformity of the microstructure.

[0050] The final product exhibits superior performance: tensile strength up to 1060 MPa, yield strength of 835 MPa, elongation of 17.5%, hardness of 393 HB, and room temperature V-notch impact energy of 34 J, further verifying the high-performance potential of the invention.

[0051] Example 3

[0052] To meet the stringent requirements for material properties in precision mechanical components, this embodiment prepared a high-strength bar with a specification of Ф10mm×2000mm. Its chemical composition was set as follows (by weight percentage): (C) 0.313%, silicon (Si) 1.04%, manganese (Mn) 2.21%, titanium (Ti) 0.34%, phosphorus (P) ≤0.02%, sulfur (S) ≤0.02%, chromium (Cr) 0.52%, vanadium (V) 0.045%, with the remainder being iron and unavoidable impurities.

[0053] The preparation process follows a standard procedure, including raw material preparation, smelting, hot rolling, and austenitization at 865°C followed by air cooling and tempering at 565°C according to the heat treatment process described in claim 2.

[0054] The final product's performance test results show that the tensile strength reaches 1080 MPa, the yield strength is 840 MPa, the elongation is 17.0%, the hardness is 410 HB, and the room temperature V-notch impact energy is 32 J, which fully meets and exceeds the specified performance indicators.

[0055] Example 4

[0056] To address the demand for high-strength, high-toughness, and good processability materials in the automotive and aerospace industries, this embodiment prepares a high-strength bar with dimensions of Ф10mm×2800mm. Its chemical composition has been slightly adjusted (by weight percentage): carbon (C) 0.330%, silicon (Si) 1.06%, manganese (Mn) 2.27%, titanium (Ti) 0.35%, phosphorus (P) ≤0.02%, sulfur (S) ≤0.02%, chromium (Cr) 0.50%, vanadium (V) 0.041%, with the remainder being iron and unavoidable impurities.

[0057] The same preparation process as in Example 3 was used. The preparation process followed a standard procedure, including raw material preparation, smelting, hot rolling, and austenitization at 865°C followed by air cooling and tempering at 565°C according to the heat treatment process described in claim 2.

[0058] By strictly controlling the quality of raw materials and heat treatment process parameters, this material achieves a tensile strength of 1100 MPa, a yield strength of 850 MPa, an elongation of 16.8%, a hardness of 415 HB, and an impact energy of 31 J. This material not only meets the basic requirements for high strength and yield strength (tensile strength ≥1050 MPa, yield strength ≥820 MPa), but also achieves excellent properties such as an elongation ≥16.5%, adjustable hardness within the range of 380-420 HB, and a room-temperature V-notch impact energy ≥30 J. Furthermore, this material exhibits good plasticity and stability during processing, providing strong support for the manufacture of complex parts.

[0059] Comparative Example

[0060] The technical solution proposed in invention patent publication number CN112458357A specifically discloses a 700MPa grade hot-rolled coiled rebar and its production method. The composition of the hot-rolled coiled rebar is: carbon (C) 0.23-0.28%, silicon (Si) 0.20-0.40%, manganese (Mn) 0.90-1.15%, vanadium (V) 0.22-0.24%, nitrogen (N) 0.025-0.040%, chromium (Cr) 0.25-0.45%, niobium (Nb) 0.02-0.04%, phosphorus (P) ≤0.035%, sulfur (S) ≤0.035%, with the balance being Fe and unavoidable impurities;

[0061] The 700MPa grade hot-rolled coiled rebar is prepared through steelmaking, continuous casting, heating, rolling, and cooling processes. This invention, through composition adjustment and process optimization, appropriately reduces the Mn content, combines it with specific amounts of C, Si, and N, and selectively adds specific alloying elements V, Nb, and Cr. Furthermore, by adjusting the billet heating temperature, rolling temperature, and cooling rate during the rolling process, the prepared hot-rolled coiled rebar meets the performance requirements of 700MPa grade hot-rolled coiled rebar steel, with a tensile strength of 935–992 MPa, a yield strength of 732–762 MPa, and an elongation after fracture ≥15%.

[0062] Table 1. Comparison of chemical composition (by weight percentage) between Examples 1-4 and Comparative Example 1

[0063] C Si Mn Ti P S Cr V Nb N Example 1 0.301 0.95 2.12 0.28 ≤0.01 ≤0.01 0.55 0.05 - - Example 2 0.310 1.01 2.20 0.30 ≤0.01 ≤0.01 0.54 0.048 - - Example 3 0.313 1.04 2.21 0.34 ≤0.01 ≤0.01 0.52 0.045 - - Example 4 0.330 1.06 2.27 0.35 ≤0.01 ≤0.01 0.50 0.041 - - Comparative Example 0.23-0.28 0.20-0.40 0.90-1.15 - ≤ 0.035 ≤ 0.035 0.25-0.45 0.22-0.24 0.02-0.04 0.025-0.04

[0064] Table 2 Comparison of mechanical properties of materials in Examples 1-3 and Comparative Example 1

[0065] Tensile strength / MPa Yield strength / MPa Elongation / % Hardness / HB Impact energy / J Example 1 1055 827 18.5 382 35 Example 2 1060 835 17.5 393 34 Example 3 1080 840 17.0 410 32 Example 4 1100 850 16.8 415 31 Comparative Example 935-992 732-762 15.0 - -

[0066] In summary, the performance indicators of the high-strength bar obtained by this application after heat treatment include: tensile strength not less than 1050 MPa, yield strength not less than 820 MPa, elongation not less than 16.5%, hardness in the range of 380-420 HB, and room temperature V-notch impact energy not less than 30 J.

[0067] Tensile strength refers to the maximum stress a material can withstand during stretching. It is an important indicator used to measure the maximum load-bearing capacity (maximum stress value) of a material when subjected to tensile force.

[0068] Yield strength: This represents the critical point at which a material transitions from elastic deformation to plastic deformation when subjected to stress. In other words, when the stress on a material reaches its yield strength, it will begin to undergo permanent deformation.

[0069] Elongation: This indicates the maximum degree of plastic deformation a material can achieve before tensile fracture, usually expressed as a percentage. A higher elongation indicates better plasticity of the material, meaning it can withstand greater deformation without breaking.

[0070] Hardness (Brinell hardness): This is a commonly used indicator for measuring the hardness of materials. Brinell hardness is calculated by pressing a cemented carbide ball of a certain diameter into the material surface and measuring the diameter of the indentation. It reflects the material's ability to resist indentation by a hard object, i.e., the material's compressive strength. Generally speaking, materials with higher Brinell hardness also have better wear resistance. This is because materials with higher hardness are more difficult to wear down during friction. Different applications have different requirements for material hardness: steel plates used in wear-resistant applications require higher Brinell hardness, while steel plates used in structural components may require moderate hardness to ensure sufficient toughness.

[0071] Room temperature V-notch impact energy: This is an indicator of a material's impact resistance at room temperature. Specifically, it represents the energy absorbed by the material in a V-notch impact test at room temperature. The higher this value, the better the material's impact resistance at low temperatures.

[0072] These indicators together constitute a comprehensive assessment of material properties, including its mechanical properties, plastic deformation capacity, and room temperature impact resistance, corresponding to the data listed in Tables 1 and 2 above:

[0073] Compared with the comparative examples, the embodiments 1-4 of the technical solution of this application have higher yield strength, tensile strength and elongation. The high-strength bar obtained by the technical solution of this application has high strength, high toughness and excellent comprehensive performance, and is particularly suitable for industrial fields with extremely high requirements for material performance, such as high-end equipment manufacturing, aerospace and other fields. It has significant technical advantages and market potential, and provides related industries with a more superior material option.

[0074] This bar achieves superior mechanical properties and toughness through a carefully designed chemical composition and heat treatment process. The chemical composition of this bar includes 0.3-0.35% carbon (C), 0.90-1.10% silicon (Si), 2.10-2.30% manganese (Mn), 0.25-0.35% titanium (Ti), ≤0.02% phosphorus (P), ≤0.02% sulfur (S), 0.48-0.55% chromium (Cr), 0.04-0.06% vanadium (V), with the remainder being iron and unavoidable impurities. During the preparation process, the bar is austenitized at 860-880℃ and then air-cooled, followed by tempering at 560-580℃. This process gives the bar excellent mechanical properties: tensile strength of 1050 MPa or more, yield strength of 820 MPa or more, while maintaining a high elongation of ≥16.5%, a moderate hardness range of 380-420 HB, and good impact toughness, with a room temperature V-notch impact energy of ≥30 J.

[0075] Specifically, the high-strength bar stock of this invention achieves ultimate performance with a tensile strength ≥1050 MPa and a yield strength ≥820 MPa by precisely controlling the content of alloying elements, particularly increasing the content of reinforcing elements such as carbon, silicon, and manganese to the optimal range, and supplementing it with the synergistic effect of elements such as titanium, vanadium, and chromium. This strength level not only far exceeds that of traditional bars but also sets a new benchmark in the field of high-end manufacturing, providing a solid material foundation for building more robust and durable products.

[0076] While pursuing high strength, this invention has not neglected the need for material toughness. Through a reasonable alloy composition and optimized heat treatment process, the material's elongation reaches ≥16.5%, exhibiting excellent toughness. This characteristic ensures that the material can maintain structural integrity and stability when subjected to complex stress or impact, effectively extending the product's service life and improving safety during use.

[0077] Furthermore, to address the application requirements in harsh working environments, this invention specifically adds an appropriate amount of chromium and strictly controls the content of harmful elements such as phosphorus and sulfur, thereby significantly improving the corrosion resistance of the material. This improvement enables the high-strength bar stock to maintain good performance in harsh environments such as humidity and corrosion, broadening the application range of the material and providing a reliable material option for more fields.

[0078] Therefore, the high-strength bars of this invention not only possess excellent performance but also good machinability. The optimized heat treatment process results in a uniform and fine internal microstructure, thereby reducing cracking and deformation during processing and improving processing efficiency and yield. This characteristic lowers production costs, enhances production efficiency, and provides strong support for large-scale applications.

[0079] Although the high-strength bars of this invention achieve significant performance improvements, their alloy composition is rationally designed and does not employ a large number of expensive rare elements, thus offering a cost advantage. This makes the material have broader application prospects and higher market competitiveness in high-end manufacturing fields, injecting new vitality into the industry's development.

[0080] In summary, the high-strength bar material of this invention exhibits significant beneficial effects in terms of strength, toughness, corrosion resistance, processing performance, and cost-effectiveness, providing a high-performance and economical material option for the high-end manufacturing field, and promoting technological progress and industrial upgrading in related industries.

[0081] It should be noted that, in this document, the term "comprising" or any other variations thereof is intended to cover non-exclusive inclusion, such that an article or device comprising a list of elements includes not only those elements but also other elements not expressly listed, or elements inherent to such an article or device. The above embodiments are merely illustrative of the technical solutions of the present invention and are not intended to limit it; although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some of the technical features; and these modifications or substitutions do not cause the essence of the corresponding technical solutions to depart from the scope of the present invention.

[0082] It should be noted that the above examples are merely specific embodiments of the present invention, and the present invention is obviously not limited to the above embodiments, with many similar variations. All modifications that can be directly derived or conceived by those skilled in the art from the content disclosed in this invention should fall within the protection scope of this invention.

[0083] The above are merely preferred embodiments of the present invention and are not intended to limit the scope of protection of the present invention. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the scope of protection of the present invention.

Claims

1. A high strength bar characterized by, Chemical composition comprising the following weight percentages: carbon 0.3-0.35%, silicon 0.90-1.10%, manganese 2.10-2.30%, titanium 0.25-0.35%, phosphorus less than or equal to 0.02%, sulfur less than or equal to 0.02%, chromium 0.48-0.55%, vanadium 0.04-0.06%, the rest being iron and inevitable impurities; The preparation method of the high-strength bar comprises raw material preparation, batching according to the chemical composition ratio, and obtaining the high-strength bar through a melting, hot rolling, heat treatment process and subsequent processing steps, wherein the heat treatment process comprises the following specific steps: Step one, first heat the bar to 860-880℃ for austenitizing treatment, and then air cool to room temperature; Step two, then heat the bar to 560-580℃ for tempering treatment.

2. A high strength bar according to claim 1, wherein The performance indicators of the high-strength bar after heat treatment include: tensile strength not less than 1050 MPa, yield strength not less than 820 MPa, elongation not less than 16.5%, hardness in the range of 380-420HB, and normal temperature V-notch impact energy not less than 30J.

3. A high strength bar according to claim 2, wherein The subsequent processing steps include rolling to adjust the shape and size of the bar.

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