Production method of superstrong sucker rod steel without surface quenching

Abstract

The invention discloses a production method of ultrahigh-strength sucker rod steel without surface quenching, which successfully adopts and develops the ultrahigh-strength sucker rod steel with excellent comprehensive mechanical properties and without surface quenching by controlling the processes of converter smelting, LF refining, continuous casting, casting blank heating furnace heating, round steel forging, thermal refining and the like. The high-strength and high-toughness steel comprises the following chemical components in percentage by mass: 0.22%-0.28% of C, 0.25%-0.32% of Si, 0.80%-0.90% of Mn, less than or equal to 0.025% of P, less than or equal to 0.015% of S, 1.20%-1.30% of Cr, 0.20%-0.25% of Ni, 0.05%-0.10% of V, 0.15%-0.20% of Mo and 0.02%-0.03% of Re. The invention aims to produce the ultrahigh-strength steel for the sucker rod without surface quenching, so that the overall service life of the sucker rod is remarkably prolonged, and the safety of the sucker rod is remarkably improved.

Description

Technical Field

[0001] The invention belongs to the technical field of smelting and forging, and in particular relates to a production method of super-strong sucker rod steel that does not require surface quenching. Background Art

[0002] With the continued development of the oil and gas industry, sucker rod steel holds broad market potential in the oil and gas extraction sector. The increasing demand for high-strength, low-cost, and durable materials is expected to further expand the market acceptance and application of these innovative steels. Traditional sucker rod steel typically requires surface hardening to improve wear resistance and strength, but this treatment increases production costs and process complexity, while also placing high demands on factory equipment and processes. By rationally selecting alloying elements in the production process, the inherent strength and toughness of the steel can be enhanced, eliminating surface hardening and streamlining the production process. This not only reduces energy consumption and costs, but also shortens production cycles, meeting the modern steel industry's pursuit of efficient and environmentally friendly production. This material offers significant advantages in improving oil well production efficiency, reducing equipment maintenance frequency, and extending service life. Furthermore, by eliminating the surface hardening step, this steel is more environmentally friendly and processable, better suited to the complex demands of oil and gas field environments. Therefore, the development of ultra-high-strength sucker rod steel that does not require surface hardening has significant technical feasibility and application prospects.

[0003] Publication No. CN116855851A introduces a new HL-grade hydrogen-resistant sucker rod steel and its preparation method. Its chemical composition contains specific proportions of elements such as C, Si, Mn, Mo, Cr, Ni, and V. Through processes such as vacuum induction furnace melting, forging, rolling, quenching and tempering heat treatment, the sucker rod steel produced has a yield strength of ≥900MPa, tensile strength ≥1100MPa, elongation ≥15%, cross-sectional reduction rate ≥60%, impact energy KV2 ≥80J, and a metallographic structure of tempered bainite, showing excellent resistance to hydrogen embrittlement.

[0004] Publication No. CN 110273101 A introduces an H-grade sucker rod and its preparation method. Its chemical composition contains specific proportions of elements such as C, Si, Mn, Cr, Mo, Nb, Ti, B, and Al. Through smelting in a 210-ton top-and-bottom combined furnace, refining with Ar blowing, continuous casting (at a specific drawing speed and superheat), rolling on a bar continuous rolling line, hot upsetting the rod head, and medium-frequency induction normalizing and tempering the entire rod, the produced sucker rod has a yield strength of Rel ≥ 795 MPa, a tensile strength of Rm ≥ 965 MPa, an elongation of A200 ≥ 10%, an area reduction of Z ≥ 45%, and an impact energy of Aku2 ≥ 60 J. It exhibits excellent comprehensive mechanical properties and corrosion fatigue resistance.

[0005] Publication No. CN 118086793 A discloses a high-strength, high-toughness steel for pump rods and its preparation method. Its chemical composition contains specific proportions of elements such as C, Si, Mn, Cr, Mo, V, Cu, and Al. The steel is smelted in an electric furnace (using 25MnV as the raw material, at specific temperatures and times, and alloyed with copper iron, ferromanganese, and ferrochromium), vacuum refining (VD degassing, controlled vacuum and time, and argon stirring), continuous casting (controlling superheat, using electromagnetic stirring and mist cooling, and stabilizing the casting speed), and rolling (controlling the heating temperature). The addition of a small amount of copper enhances the steel's wear and corrosion resistance, resulting in high overall mechanical properties.

[0006] This patent discloses an ultra-high-strength steel for sucker rods that does not require surface quenching and a preparation method thereof. The chemical composition of the steel contains elements such as C, Si, Mn, P, S, Cr, Ni, V, Mo, and Re in specific proportions. Through processes such as converter smelting, LF refining, continuous casting, heating in a billet heating furnace, round steel forging, and tempering treatment, the parameters of each link are controlled. The sucker rod steel produced has a tensile strength ≥1300MPa, an elongation after fracture ≥10%, a cross-sectional reduction rate A ≥60%, a Rockwell hardness HRC ≥40J, an impact toughness KU2 ≥100J, and a fatigue life ≥1,000,000 times. In addition, by optimizing the chemical composition and process, no surface quenching is required, which improves the performance of the steel in various environments and reduces cost and energy consumption.

[0007] This patented design utilizes the combined effects and optimized ratios of multiple alloying elements, combined with a unique preparation process, to achieve high strength while significantly enhancing the material's comprehensive properties, including toughness, fatigue resistance, corrosion resistance, and high-temperature stability. This achieves ultra-high strength without the need for surface quenching, simplifying the production process and reducing costs and energy consumption. The resulting steel boasts even higher performance indicators, such as higher tensile strength and longer fatigue life, making it more adaptable to complex and harsh oil well environments. Furthermore, the patented design utilizes more sophisticated and comprehensive process control, facilitating the stable production of high-quality sucker rod steel. Summary of the Invention

[0008] The purpose of the present invention is to provide a method for producing ultra-strong sucker rod steel that does not require surface quenching. The method utilizes a process that is synergistically optimized based on the principle of composite alloying of Cr, Ni, V, Mo, and Re to significantly improve the performance of forged round steel, thereby producing ultra-high-strength sucker rod steel that does not require surface quenching, thereby significantly improving the overall life and safety of the sucker rod.

[0009] In order to solve the above technical problems, the present invention adopts the following technical solutions:

[0010] The present invention provides a production method for ultra-strong sucker rod steel that does not require surface quenching, comprising converter smelting, LF refining, continuous casting, heating in a casting furnace, round steel forging, and quenching and tempering treatment, and is characterized in that:

[0011] Converter smelting: Combined-blowing converter smelting uses a double-slag method for smelting operations. During the tapping process, slag balls or slag plugs are used to prevent slag. Silicon manganese and ferrosilicon are used for deoxidation and alloying, while silicon aluminum calcium and barium are used for final deoxidation. Deoxidizer is added when the molten steel reaches 1 / 3 of the tapping volume, and alloy is added after the deoxidizer is added. The amount of alloy added is adjusted accordingly based on the final carbon content and tapping volume.

[0012] LF refining: After the converter completes tapping, the ladle is hoisted to the refining station by an overhead crane, and refining operations are then carried out under argon blowing conditions throughout the entire process. During heating, the heating rate is gradually increased from low to high levels, and slag formation, fine-tuning, and heating operations are carried out according to changes in the molten steel composition and temperature. In the later stage of refining, a silicon calcium wire is fed, and the soft blowing time is ≥10 minutes.

[0013] Continuous casting: Adopting small square billet continuous casting process, using mold protection slag, working casting speed is 1.8-2.0m / min, superheat temperature is 25-30℃, full protection casting is implemented throughout the process, the billet is placed in the slow cooling pit, and the slow cooling time is ≥36 hours;

[0014] Heating in billet heating furnace: Billet heating temperature is 1080~1120℃, with an allowable temperature difference of ≤30℃. The total heating time is controlled at 2h to prevent overheating, overburning and decarburization. The temperature is raised slowly to ensure uniform billet heating temperature and reduce temperature difference.

[0015] Round steel forging: initial forging temperature 1030~1050℃, final forging temperature 930~970℃;

[0016] Quenching and tempering treatment: After forging, quenching and tempering treatment is carried out, quenching in water at 880±10℃, tempering at 5000±10℃, and cooling in water;

[0017] The chemical composition of the sucker rod steel includes, by weight percentage, C 0.22% to 0.28%, Si 0.25% to 0.32%, Mn 0.80% to 0.90%, P ≤ 0.025%, S ≤ 0.015%, Cr 1.20% to 1.30%, Ni 0.20% to 0.25%, V 0.05% to 0.10%, Mo 0.15% to 0.20%, Re 0.02% to 0.03%, and the remainder is Fe and unavoidable trace impurities, with a total weight fraction of 100%.

[0018] Furthermore, a continuous casting process of small square billets 150mm×150mm is adopted.

[0019] Further, quenching and tempering treatment: quenching and tempering treatment is carried out after forging, quenching in water at 880℃, tempering at 500℃, and cooling in water.

[0020] Furthermore, the chemical composition of the sucker rod steel includes, by mass percentage, C 0.23%, Si 0.27%, Mn 0.86%, P 0.012%, S 0.003%, Cr 1.28%, Ni 0.22%, V 0.07%, Mo 0.18%, Re 0.025%, and the remainder is Fe and unavoidable impurities, with a total mass fraction of 100%.

[0021] Furthermore, the chemical composition of the sucker rod steel includes, by mass percentage, C 0.24%, Si 0.28%, Mn 0.87%, P 0.014%, S 0.004%, Cr 1.26%, Ni 0.23%, V 0.06%, Mo 0.17%, Re 0.026%, and the remainder is Fe and unavoidable impurities, with a total mass fraction of 100%.

[0022] Furthermore, the chemical composition of the sucker rod steel includes, by mass percentage, C 0.24%, Si 0.27%, Mn 0.85%, P 0.015%, S 0.003%, Cr 1.27%, Ni 0.22%, V 0.06%, Mo 0.17%, Re 0.024%, and the remainder is Fe and unavoidable impurities, with a total mass fraction of 100%.

[0023] Furthermore, the finished product specification is φ50mm.

[0024] Furthermore, the longitudinal mechanical properties meet the requirements of Rm≥1300MPa, Rockwell hardness HRC≥40, elongation after fracture ≥10%, cross-sectional expansion ratio ≥60%, and fatigue life ≥1,000,000 times.

[0025] Furthermore, the fatigue life of the super-strong sucker rod steel without surface quenching is 1.16×10 6 to 2.05×10 6 Second-rate.

[0026] The mechanism of action of alloying elements is as follows:

[0027] Cr is an effective element for strengthening ferrite and pearlite, increasing the strength and hardness of steel, making it more capable of bearing loads in high-stress environments. This is particularly important for the load-bearing and tensile strength requirements of sucker rods in oil and gas production. Cr significantly improves the hardenability of the steel, ensuring a uniform hardness distribution in the sucker rod, thereby enhancing the overall performance of the material. The Cr mass fraction in this patent is 1.20-1.30%.

[0028] Nickel increases the toughness of steel, preventing brittle fracture in extreme environments. Toughness is particularly critical for sucker rod steel operating under the harsh conditions deep within oil wells. Nickel helps improve the corrosion resistance of steel, making it more resistant to corrosive environments such as those containing sulfur and salt. Nickel improves the plasticity of steel, making it less susceptible to fracture under high stress and suitable for withstanding the complex loads of oil wells. The nickel mass fraction in this patent is 0.20-0.25%.

[0029] V refines the steel's grain structure by forming carbides, improving the material's strength and toughness. Grain refinement also enhances impact toughness and wear resistance, which directly impacts the fatigue resistance of the sucker rod. The addition of V allows the material to maintain high strength even under high-temperature conditions, making it suitable for deep and high-temperature oil well environments. An appropriate amount of V improves the steel's hardenability, ensuring a uniform distribution of hardness and toughness in the sucker rod after heat treatment. The V mass fraction in this patent is 0.05-0.10%.

[0030] Mo helps increase the material's high-temperature strength, preventing softening at high temperatures while also increasing the steel's hardness. Mo effectively inhibits pitting and crevice corrosion in hydrogen- and sulfur-containing environments, significantly extending the material's life in oil well environments. Mo helps reduce deformation (creep resistance) under prolonged stress, ensuring the stability of the sucker rod under continuous load. The Mo mass fraction in this patent is 0.15-0.20%.

[0031] Re can effectively improve the high-temperature stability and oxidation resistance of steel, enabling the material to maintain excellent performance in the high-temperature environment of oil wells. Re in microalloyed steel helps reduce stress corrosion cracking, thereby improving the durability of pump rods. Re promotes the steel's grain refinement mechanism, resulting in higher strength while maintaining high toughness. The mass fraction of Re in this patent is 0.02-0.03%.

[0032] By optimizing the ratio of these elements, the strength, toughness, wear resistance and corrosion resistance of sucker rod steel can achieve an ideal balance, thereby improving the overall service life and reliability of oil and gas production equipment.

[0033] Compared with the prior art, the present invention has the following beneficial technical effects:

[0034] (1) By optimizing the chemical composition and tempering process, ultra-high strength and wear resistance can be achieved without additional surface quenching treatment. Since the high-frequency surface quenching process is omitted, a large amount of electricity can be saved, energy consumption can be reduced, and the production cost per ton is reduced by about RMB 500, which is extremely effective in energy saving and consumption reduction. (2) The steel produced by the present invention has high tensile strength (Rm ≥ 1300MPa), good toughness (elongation after fracture ≥ 10%) and fatigue resistance (fatigue life ≥ 1,000,000 times), which significantly improves the service life and safety of the pumping rod in complex oil well environments. (3) The optimization of alloying elements (such as the reasonable combination of Cr, Ni, Mo and Re) significantly improves the corrosion resistance of the material in corrosive environments such as sulfur and salt, as well as the oxidation resistance and creep resistance in high temperature environments. (4) The present invention optimizes the preparation process, replaces the electric furnace with a converter, reduces the preparation cost, degassing and removes inclusions, improves the cleanliness of the material, and thus significantly improves the strength and toughness of the steel and the life of the material. The preparation method is simple, has low energy consumption, and is suitable for the existing industrial equipment level. (5) The preparation process is simple, suitable for the existing industrial equipment conditions, and can stably and efficiently produce steel for pumping rods that meet ultra-high strength requirements, with broad market application prospects. DETAILED DESCRIPTION

[0035] Example 1:

[0036] The present invention provides a method for preparing ultra-high strength steel for sucker rods that does not require surface quenching. The production process is carried out according to the following steps:

[0037] Combined-blown converter smelting uses a double-slag process. During the tapping process, slag balls or plugs are used to prevent slag. Silicon manganese and ferrosilicon are used for deoxidation and alloying, while silicon aluminum calcium and barium are used for final deoxidation. Deoxidizer is added when the molten steel reaches 1 / 3 of the tapping volume, and alloy is added after the deoxidizer. The amount of alloy added is adjusted accordingly based on the final carbon content and the tapping volume.

[0038] After the converter completes tapping, the ladle is hoisted to the refining station by an overhead crane, where refining operations begin under argon blowing throughout the process. Heating is performed by gradually increasing the heating rate from low to high levels, with slagging, fine-tuning, and heating operations performed based on changes in the molten steel's composition and temperature. A calcium silicon wire is added in the final stages of refining, with a soft blowing time of 13 minutes.

[0039] Further: adopting the continuous casting process of small square billets (150mm×150mm), using mold protection slag, the working casting speed is 1.8m / min, the superheat temperature is 27℃, and the full protection casting is implemented. The billets are placed in the slow cooling pit and the slow cooling time is 36 hours;

[0040] Further: the billet heating temperature is 1095℃, the total heating time is controlled at 2h, overheating, overburning and decarburization are prevented, the temperature is raised slowly to ensure uniform billet heating temperature and reduce temperature difference;

[0041] The initial forging temperature is 1032°C, and the final forging temperature is 945°C. The finished product size is φ50mm. After forging, it is tempered by quenching in water at 880°C, tempering at 500°C, and cooling in water.

[0042] Example 2-3:

[0043] Except for some specific process parameters that are different from those in Example 1, the rest of Examples 2-3 are exactly the same as those in Example 1. Specific process parameters are shown in Table 1.

[0044] Table 1 Process parameters of each embodiment

[0045]

[0046] Comparative Example 1:

[0047] Comparative Example 1 is identical to Example 1 except that the forging process is replaced by the rolling process. The initial rolling temperature of this comparative example is 1032°C, and the final rolling temperature is 945°C.

[0048] Comparative Examples 2-3:

[0049] Comparative Example 2-3 is identical to Example 1 except that the forging process is replaced by a rolling process and the rare earth element Re is not added. The initial rolling temperature of this comparative example is 1032°C and the final rolling temperature is 945°C.

[0050] Comparative Example 4:

[0051] Comparative Example 4 is identical to Example 1 except for the higher forging temperature. The initial rolling temperature in this comparative example is 1082°C and the final rolling temperature is 995°C.

[0052] Comparative Example 5:

[0053] Comparative Example 5 is identical to Example 1 except for the lower forging temperature. The initial rolling temperature in this comparative example is 982°C and the final rolling temperature is 895°C.

[0054] The ultra-high strength sucker rod steel that does not require surface quenching and is produced by adopting the chemical composition and process flow of the present invention can achieve longitudinal mechanical properties of the steel of Rm ≥ 1300 MPa, Rockwell hardness HRC ≥ 40, elongation after fracture ≥ 10%, cross-sectional expansion ratio ≥ 60%, fatigue life ≥ 1,000,000 times, and no cracks, scars, folds or inclusions on the steel surface.

[0055] Table 2 shows the chemical compositions of three embodiments and five comparative examples of the present invention. Tables 3 and 4 further illustrate the present invention.

[0056] Table 2 Chemical composition of various examples of ultra-high strength sucker rod steel without surface quenching (mass percentage / %)

[0057] Example C Si Mn P S Cr Ni V Mo Re Example 1 0.23 0.27 0.86 0.012 0.003 1.28 0.22 0.07 0.18 0.025 Example 2 0.24 0.28 0.87 0.014 0.004 1.26 0.23 0.06 0.17 0.026 Example 3 0.24 0.27 0.85 0.015 0.003 1.27 0.22 0.06 0.17 0.024 Comparative Example 1 0.23 0.28 0.86 0.013 0.004 1.27 0.22 0.06 0.18 0.025 Comparative Example 2 0.24 0.27 0.85 0.017 0.009 1.25 0.21 0.07 0.16 —— Comparative Example 3 0.23 0.27 0.87 0.018 0.010 1.28 0.23 0.06 0.17 —— Comparative Example 4 0.24 0.27 0.85 0.015 0.009 1.26 0.22 0.06 0.18 —— Comparative Example 5 0.23 0.28 0.87 0.013 0.010 1.27 0.21 0.07 0.16 ——

[0058] Table 3 Mechanical properties of various examples of ultra-high strength sucker rod steel without surface quenching

[0059]

[0060]

[0061] Table 4 Non-metallic inclusions and austenite grain size of various examples of ultra-high strength sucker rod steel without surface quenching

[0062]

[0063] It can be seen from Tables 2 to 4 that:

[0064] (1) Compared with comparative example 1, the embodiment shows significant advantages in terms of strength, toughness, fatigue life, grain size and high temperature resistance. These performance improvements are attributed to the optimization of the forging process and the improvement of the material organization. The forging process can better improve the grain flow direction of the material, refine the grain structure, reduce defects, and thus improve the strength and hardness of the material. The forging process can significantly improve the ductility and plasticity of the material through higher plastic deformation and fine control, making it more resilient in high stress environments. The forging process can optimize the fiber structure inside the material, reduce internal defects and stress concentration, and improve fatigue resistance, so that the sucker rod has a longer life and higher safety under repeated loads. The forging process can significantly refine the grain structure and improve the uniformity of the grains through large deformation and controlled cooling rate. The austenite grain size of embodiment 1 is 8.5, while that of comparative example 1 is only 6.5.

[0065] (2) The embodiment significantly improves the cleanliness of steel by adding an appropriate amount of rare earth elements (Re 0.02% - 0.03%). Rare earth elements have strong deoxidation and desulfurization effects, which can effectively reduce the number and size of non-metallic inclusions. The embodiment significantly improves the cleanliness of steel by adding an appropriate amount of rare earth elements (Re 0.02% - 0.03%). Rare earth elements have strong deoxidation and desulfurization effects, which can effectively reduce the number and size of non-metallic inclusions. The fatigue life of the embodiment reaches 1.16×10 6 to 2.05×10 6 times, while the comparative example 2-3 was only 0.75×10 6 to 1.00×106 Rare earth elements can reduce the stress concentration effect caused by inclusions, thereby enhancing the material's fatigue resistance and extending its service life.

[0066] (3) The forging temperature of Example 4 is too high (initial forging temperature 1082°C, final forging temperature 995°C), which leads to grain growth and a tendency for the material to overburn, thereby reducing the mechanical properties. The tensile strength and toughness of Example 4 are significantly lower than those of the embodiment, and the cross-sectional shrinkage rate and fatigue life are both poor, especially in high stress environments, where brittle fracture is prone to occur. If the forging temperature is too low (initial forging temperature 982°C, final forging temperature 895°C), the deformation amount will be insufficient, the fiber structure inside the metal will not be fully extended, and the grain refinement effect will be poor. Although the strength and hardness of the material are close to those of the embodiment, the toughness and fatigue performance are slightly inferior. The embodiment achieves the best balance of strength, hardness, toughness and fatigue performance through reasonable forging temperature control (initial forging temperature 1030-1050°C, final forging temperature 930-970°C).

[0067] As can be seen from the above examples and comparative examples:

[0068] (1) The examples are superior to the comparative examples in terms of mechanical properties such as tensile strength, hardness, reduction of area, and elongation. The tensile strength of the examples reaches 1323-1334 MPa, significantly higher than that of the comparative examples (approximately 1225-1327 MPa); at the same time, the reduction of area and elongation are also higher, demonstrating excellent toughness and plasticity. This performance improvement is due to the optimization of the alloy composition and the rational control of the heat treatment process, making the material more suitable for high-stress, complex load environments.

[0069] (2) The fatigue life of the embodiment is 1.16×10 6 to 2.05×10 6 times, while the fatigue life of most comparison samples is less than 1.60×10 6 times (the lowest is only 0.75×10 6 times). The embodiment effectively reduces the initiation and expansion of fatigue cracks by refining the grains and reducing the inclusion content, thereby improving the fatigue resistance and significantly extending the service life of the material under cyclic loads. (3) The embodiment significantly refines the grains (austenite grain size is about 8 levels) and reduces the content of non-metallic inclusions (A fine inclusions ≤ 0.5) through the synergistic effect of forging process and rare earth elements, while some of the comparative examples have coarser grains (6.5-7 levels) and more inclusions (A fine inclusions are as high as 1.0). This organizational optimization improves the strength, toughness and corrosion resistance of the material, while enhancing the high temperature stability and wear resistance of the material, adapting to more complex use environments.

[0070] The embodiments described above are merely descriptions of preferred embodiments of the present invention and are not intended to limit the scope of the present invention. Without departing from the spirit of the present invention, various modifications and improvements made to the technical solutions of the present invention by persons skilled in the art should fall within the scope of protection defined by the claims of the present invention.

Claims

1. A method for producing ultra-strong sucker rod steel that does not require surface quenching, comprising converter smelting, LF refining, continuous casting, heating in a casting furnace, round steel forging, and quenching and tempering treatment, characterized in that: Converter smelting: Combined-blowing converter smelting uses a double-slag method for smelting operations. During the tapping process, slag balls or slag plugs are used to prevent slag. Silicon manganese and ferrosilicon are used for deoxidation and alloying, while silicon aluminum calcium and barium are used for final deoxidation. Deoxidizer is added when the molten steel reaches 1 / 3 of the tapping volume, and alloy is added after the deoxidizer is added. The amount of alloy added is adjusted accordingly based on the final carbon content and tapping volume. LF refining: After the converter completes tapping, the ladle is hoisted to the refining station by an overhead crane, and refining operations are then carried out under argon blowing conditions throughout the entire process. During heating, the heating rate is gradually increased from low to high levels, and slag formation, fine-tuning, and heating operations are carried out according to changes in the molten steel composition and temperature. In the later stage of refining, a silicon calcium wire is fed, and the soft blowing time is ≥10 minutes. Continuous casting: Adopting small square billet continuous casting process, using mold protection slag, working casting speed is 1.8-2.0m / min, superheat temperature is 25-30℃, full protection casting is implemented throughout the process, the billet is placed in the slow cooling pit, and the slow cooling time is ≥36 hours; Heating in billet heating furnace: Billet heating temperature is 1080~1120℃, with an allowable temperature difference of ≤30℃. The total heating time is controlled at 2h to prevent overheating, overburning and decarburization. The temperature is raised slowly to ensure uniform billet heating temperature and reduce temperature difference. Round steel forging: initial forging temperature 1030~1050℃, final forging temperature 930~970℃; Quenching and tempering treatment: After forging, quenching and tempering treatment is carried out, quenching in water at 880±10℃, tempering at 5000±10℃, and cooling in water; The chemical composition of the sucker rod steel includes, by weight percentage, C 0.22% to 0.28%, Si 0.25% to 0.32%, Mn 0.80% to 0.90%, P ≤ 0.025%, S ≤ 0.015%, Cr 1.20% to 1.30%, Ni 0.20% to 0.25%, V 0.05% to 0.10%, Mo 0.15% to 0.20%, Re 0.02% to 0.03%, and the remainder is Fe and unavoidable trace impurities, with a total weight fraction of 100%.

2. The method for producing super-strong sucker rod steel without surface quenching according to claim 1, characterized in that: The continuous casting process of small square billets 150mm×150mm is adopted.

3. The method for producing super-strong sucker rod steel without surface quenching according to claim 1, characterized in that: Quenching and tempering treatment: After forging, quenching and tempering treatment is carried out, quenching in water at 880℃, tempering at 500℃, and cooling in water.

4. The method for producing super-strong sucker rod steel without surface quenching according to claim 1, characterized in that: The chemical composition of the sucker rod steel includes, by weight percentage, C 0.23%, Si 0.27%, Mn 0.86%, P 0.012%, S 0.003%, Cr 1.28%, Ni 0.22%, V 0.07%, Mo 0.18%, Re 0.025%, and the remainder is Fe and unavoidable impurities, with a total weight fraction of 100%.

5. The method for producing super-strong sucker rod steel without surface quenching according to claim 1, characterized in that: The chemical composition of the sucker rod steel includes, by weight percentage, C 0.24%, Si 0.28%, Mn 0.87%, P 0.014%, S 0.004%, Cr 1.26%, Ni 0.23%, V 0.06%, Mo 0.17%, Re 0.026%, and the remainder is Fe and unavoidable impurities, with a total weight fraction of 100%.

6. The method for producing super-strong sucker rod steel without surface quenching according to claim 1, characterized in that: The chemical composition of the sucker rod steel includes, by weight percentage, C 0.24%, Si 0.27%, Mn 0.85%, P 0.015%, S 0.003%, Cr 1.27%, Ni 0.22%, V 0.06%, Mo 0.17%, Re 0.024%, and the remainder is Fe and unavoidable impurities, with a total weight fraction of 100%.

7. The method for producing super-strong sucker rod steel without surface quenching according to claim 1, characterized in that: The finished product specification is φ50mm.

8. The method for producing super-strong sucker rod steel without surface quenching according to claim 1, characterized in that: The longitudinal mechanical properties meet the requirements of Rm≥1300MPa, Rockwell hardness HRC≥40, elongation after fracture ≥10%, cross-sectional expansion ratio ≥60%, and fatigue life ≥1,000,000 times.

9. The method for producing super-strong sucker rod steel without surface quenching according to claim 1 or 8, characterized in that: The fatigue life of the super-strong sucker rod steel without surface quenching is 1.16×10 6 to 2.05×10 6 Second-rate.

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