Heat treatment process of 25CrMoA round steel for sucker rod

Abstract

The invention discloses a heat treatment process of 25CrMoA round steel for a sucker rod, which comprises the following steps: quenching: putting a rough-machined round steel blank sample for the sucker rod into a heating furnace, heating to 865-900 DEG C, keeping the temperature for 50-70 minutes, and then carrying out water quenching; the quenched sample is put into a heating furnace to be heated to 470-530 DEG C, heat preservation is conducted for 120-150 min, and the sample is taken out to be cooled in water; the round steel comprises the following chemical components in percentage by mass: 0.19 to 0.21 percent of C, 0.25 to 0.28 percent of Si, 0.76 to 0.79 percent of Mn, less than or equal to 0.016 percent of P, less than or equal to 0.012 percent of S, 0.79 to 0.87 percent of Cr, 0.18 to 0.22 percent of Mo and the balance of iron and impurities. Through a reasonable heat treatment process, the round steel has good comprehensive mechanical properties, so that the overall service life of the round steel for the sucker rod is remarkably prolonged, and the safety of the round steel is remarkably improved.

Description

Technical Field

[0001] The invention belongs to the technical field of heat treatment of round steel for pumping rods, and in particular relates to a heat treatment process of 25CrMoA round steel for pumping rods. Background Art

[0002] A reasonable heat treatment system is essential for round steel for pumping rods. It can not only optimize the mechanical properties and corrosion resistance of steel, improve fatigue resistance and toughness, but also control internal defects, improve processing performance, ensure product consistency and stability, and thus meet the strict requirements of the oil extraction industry. The oil well environment often contains corrosive media such as brine, hydrogen sulfide, etc. Through proper heat treatment, a dense surface layer or uniform internal structure can be formed to improve the corrosion resistance of round steel and ensure the long-term stability of pumping rods in harsh environments. Through the study of the phase transition point of 25CrMoA round steel for pumping rods, it is found that the heat treatment austenitization temperature of round steel for pumping rods should be controlled at 865℃-900℃, and the holding time should be 50-70min; water with a higher cooling rate is selected as the quenching medium to obtain high strength and good toughness. The tempering temperature should be controlled at 470-530℃, and the tempering holding time should be 120-150min. The quenching temperature, tempering temperature and holding time all have an impact on the performance of the material. The heat treatment process of the round steel for the sucker rod of the present invention determines a set of heat treatment systems that can ensure the stable performance of the steel by studying the heat treatment heating system, including the effects of the quenching temperature, tempering temperature and holding time on the organization and performance.

[0003] Literature 1 studied the changing trend of the yield strength ratio of 25CrMo axle steel for high-speed rail at different quenching and tempering temperatures. Through tensile tests and microstructure analysis, the influence law and mechanism of quenching and tempering temperatures on the yield strength ratio were obtained. This patent introduces a heat treatment process for 25CrMoA round steel for sucker rods, including quenching and tempering steps. By controlling the temperature and holding time, the comprehensive mechanical properties of the round steel are improved. This patent focuses on the optimization of the heat treatment process of 25CrMoA round steel for sucker rods, and improves the performance by precisely controlling the quenching and tempering parameters (temperature, time). The research on the heat treatment process is more in-depth and more targeted, which can better guarantee the performance of the steel.

[0004] Document 2: A heat treatment method for 25CrMo alloy steel hollow axle material for high-speed railway passenger cars, including pretreatment, quenching and tempering steps. The mechanical properties of the treated axle material meet the requirements of relevant standards. This patent introduces a heat treatment process for 25CrMoA round steel for sucker rods, including quenching and tempering steps. By controlling the temperature and holding time, the comprehensive mechanical properties of the round steel are improved, and examples and comparative examples are given.

[0005] Document 3 introduces a heat treatment method for a fully hollow half-axle (25CrMo4 alloy steel) of an automobile. This patent focuses on the optimization of the heat treatment process of 25CrMoA round steel for sucker rods. The performance is improved by precisely controlling the quenching and tempering parameters (temperature, time). The research on the heat treatment process is more in-depth and more targeted, which can better guarantee the performance of the steel. Summary of the invention

[0006] The purpose of the present invention is to provide a heat treatment process for 25CrMoA round steel for pumping rods, so that the round steel has good comprehensive mechanical properties through a reasonable heat treatment process, thereby significantly improving the overall life and safety of the round steel for pumping rods.

[0007] In order to solve the above technical problems, the present invention adopts the following technical solutions:

[0008] The invention discloses a heat treatment process of 25CrMoA round steel for a sucker rod, comprising the following steps: (1) quenching: placing a rough-machined round steel blank sample for a sucker rod into a heating furnace, heating it to 865°C-900°C, keeping it warm for 50-70 minutes, and then quenching and water quenching; (2) tempering: placing the quenched sample into a heating furnace, heating it to 470-530°C, keeping it warm for 120-150 minutes, and then taking out the sample and cooling it in water;

[0009] The chemical composition of the 25CrMoA round steel for the sucker rod is as follows: C 0.19-0.21%, Si 0.25-0.28%, Mn 0.76-0.79%, P≤0.016%, S≤0.012%, Cr 0.79-0.87%, Mo 0.18-0.22%, and the rest is iron and unavoidable impurities.

[0010] Furthermore, the chemical composition of the 25CrMoA round steel for the sucker rod is as follows by mass percentage: C 0.19%, Si 0.26%, Mn 0.78%, P 0.014%, S 0.009%, Cr 0.85%, Mo 0.20%, and the rest is iron and unavoidable impurities.

[0011] Furthermore, the chemical composition of the 25CrMoA round steel for the sucker rod is as follows by mass percentage: C 0.20%, Si 0.28%, Mn 0.76%, P 0.015%, S 0.010%, Cr 0.87%, Mo 0.20%, and the rest is iron and unavoidable impurities.

[0012] Furthermore, the chemical composition of the 25CrMoA round steel for the sucker rod is as follows by mass percentage: C 0.21%, Si 0.25%, Mn 0.79%, P 0.015%, S 0.008%, Cr 0.79%, Mo 0.20%, and the rest is iron and unavoidable impurities.

[0013] Further, proceed as follows:

[0014] (1) Quenching: Place the rough-machined round steel blank of the sucker rod into a heating furnace, heat it to 870°C, keep it warm for 50 minutes, and then quench it with water;

[0015] (2) Tempering: Place the quenched sample into a heating furnace, heat to 485°C, keep warm for 120 min, then take out the sample and cool it in water.

[0016] Further, proceed as follows:

[0017] (1) Quenching: Place the rough-machined round steel blank of the sucker rod into a heating furnace, heat it to 890°C, keep it warm for 70 minutes, and then quench it with water;

[0018] (2) Tempering: Place the quenched sample into a heating furnace, heat to 515°C, keep warm for 150 min, then take out the sample and cool it in water.

[0019] Further, proceed as follows:

[0020] (1) Quenching: Place the rough-machined round steel blank of the sucker rod into a heating furnace, heat it to 880°C, keep it warm for 60 minutes, and then quench it with water;

[0021] (2) Tempering: Place the quenched sample in a heating furnace, heat to 500°C, keep warm for 130 minutes, then take out the sample and cool it in water.

[0022] Compared with the prior art, the beneficial technical effects of the present invention are:

[0023] (1) By optimizing the quenching and tempering temperature and holding time, the present invention significantly improves the yield strength, tensile strength and elongation of 25CrMoA round steel, so that it has excellent strength and plasticity and can better cope with working requirements in high-strength environments; (2) Reasonable control of tempering temperature and holding time enhances the impact toughness of the material, improves the impact resistance of the material under low temperature and harsh working conditions, and extends the service life of the product; (3) The heat treatment process of the present invention reduces the non-metallic inclusions inside the material, improves the cleanliness of the steel, and further improves the uniformity and corrosion resistance of the material, making it suitable for long-term use in harsh environments. DETAILED DESCRIPTION

[0024] Embodiment 1:

[0025] The heat treatment process of the present invention is performed on a 25CrMoA round steel bar for a pumping rod, and is performed in the following steps:

[0026] (1) Quenching: Place the rough-machined round steel blank of the sucker rod into a heating furnace, heat it to 870°C, keep it warm for 50 minutes, and then quench it with water;

[0027] (2) Tempering: Place the quenched sample into a heating furnace, heat to 485°C, keep warm for 120 min, then take out the sample and cool it in water.

[0028] Embodiment 2:

[0029] The heat treatment process of the present invention is performed on a 25CrMoA round steel bar for a pumping rod, and is performed in the following steps:

[0030] (1) Quenching: Place the rough-machined round steel blank of the sucker rod into a heating furnace, heat it to 890°C, keep it warm for 70 minutes, and then quench it with water;

[0031] (2) Tempering: Place the quenched sample into a heating furnace, heat to 515°C, keep warm for 150 min, then take out the sample and cool it in water.

[0032] Embodiment 3:

[0033] The heat treatment process of the present invention is performed on a 25CrMoA round steel bar for a pumping rod, and is performed in the following steps:

[0034] (1) Quenching: Place the rough-machined round steel blank of the sucker rod into a heating furnace, heat it to 880°C, keep it warm for 60 minutes, and then quench it with water;

[0035] (2) Tempering: Place the quenched sample in a heating furnace, heat to 500°C, keep warm for 130 minutes, then take out the sample and cool it in water.

[0036] Comparative Example 1:

[0037] The heat treatment process of the present invention is performed on a 25CrMoA round steel bar for a pumping rod, and is performed in the following steps:

[0038] (1) Quenching: Place the rough-machined round steel blank of the sucker rod into a heating furnace, heat it to 860°C, keep it warm for 30 minutes, and then quench it with water;

[0039] (2) Tempering: Place the quenched sample into a heating furnace, heat to 440°C, keep warm for 100 min, then take out the sample and cool it in water.

[0040] Comparative Example 2:

[0041] The heat treatment process of the present invention is performed on a 25CrMoA round steel bar for a pumping rod, and is performed in the following steps:

[0042] (1) Quenching: Place the rough-machined round steel blank of the sucker rod into a heating furnace, heat it to 930°C, keep it warm for 60 minutes, and then quench it with water;

[0043] (2) Tempering: Place the quenched sample into a heating furnace, heat it to 540°C, keep it warm for 150 min, then take out the sample and cool it in water.

[0044] Comparative Example 3:

[0045] The heat treatment process of the present invention is performed on a 25CrMoA round steel bar for a pumping rod, and is performed in the following steps:

[0046] (1) Quenching: Put the rough-machined round steel blank of the sucker rod into a heating furnace, heat it to 880°C, keep it warm for 40 minutes, and then quench it with oil quenching;

[0047] (2) Tempering: Place the quenched sample in a heating furnace, heat to 500°C, keep warm for 90 minutes, then take out the sample and cool it in air.

[0048] Comparative Example 4:

[0049] The heat treatment process of the present invention is performed on a 25CrMoA round steel bar for a pumping rod, and is performed in the following steps:

[0050] (1) Quenching: Place the rough-machined round steel blank of the sucker rod into a heating furnace, heat it to 870°C, keep it warm for 30 minutes, and then quench it with water;

[0051] (2) Tempering: Place the quenched sample into a heating furnace, heat to 485°C, keep warm for 80 min, then take out the sample and cool it in water.

[0052] The main heat treatment parameters of each embodiment and comparative example are shown in Table 1.

[0053] Table 1 Main heat treatment parameters of each embodiment and comparative example

[0054]

[0055] The chemical compositions of the embodiments and comparative examples are shown in Table 2. After the heat treatment, the rough-machined blank samples were fine-machined and various performance tests were performed. The test results are shown in Tables 3, 4 and 5. It can be seen from Tables 3, 4 and 5 that various performance indicators are higher than the index requirements, and the performance of the samples after heat treatment is qualified.

[0056] Table 2 Chemical composition of each embodiment and comparative example (mass percentage %)

[0057] Example C Si Mn P S Cr Mo Example 1 0.19 0.26 0.78 0.014 0.009 0.85 0.20 Example 2 0.20 0.28 0.76 0.015 0.010 0.87 0.20 Example 3 0.21 0.25 0.79 0.015 0.008 0.79 0.20 Comparative Example 1 0.23 0.28 0.80 0.013 0.007 0.88 0.25 Comparative Example 2 0.21 0.29 0.82 0.015 0.009 0.90 0.23 Comparative Example 3 0.18 0.24 0.75 0.011 0.006 0.80 0.18 Comparative Example 4 0.19 0.26 0.78 0.013 0.005 0.85 0.20

[0058] Table 3 Mechanical properties of each embodiment and comparative example after heat treatment at room temperature

[0059]

[0060] Table 3 Impact toughness of each embodiment and comparative example after heat treatment

[0061]

[0062]

[0063] Table 5 Non-metallic inclusions after heat treatment

[0064]

[0065] It can be seen from the above embodiments and comparative examples that: (1) Compared with comparative example 1, each embodiment prolongs the tempering holding time, so that the austenite grains grow fully, so that the material achieves a good balance between strength and toughness. The appropriate increase in tempering temperature also further enhances the toughness and plasticity of the material, so that the elongation and impact toughness far exceed the performance of comparative example 1. (2) Compared with comparative example 2, the quenching temperature of each embodiment is moderately reduced to prevent excessive grain growth and significantly improve the ductility and impact toughness of the material. The tempering temperature is appropriately reduced and controlled within a reasonable range to ensure the high strength and good plasticity of the material. This optimization treatment overcomes the damage to strength and toughness caused by excessive temperature and achieves excellent comprehensive performance. (3) Compared with comparative example 3, each embodiment significantly improves the strength of the material by using water quenching instead of oil quenching. The appropriate extension of tempering time also further improves plasticity and toughness, so that the comprehensive performance of the material far exceeds that of comparative example 3. (4) Compared with comparative example 3, each embodiment prolongs the quenching heating holding time to 50-70 minutes to ensure complete transformation of austenite and improve the strength and toughness of the material. The tempering and holding time is increased to 120-150 minutes to ensure that the internal stress of the material is fully released, further improving the ductility and impact toughness.

[0066] The heat treatment system of the present invention has the following advantages: (1) In the embodiment, by extending the holding time of quenching and tempering, the yield strength, tensile strength and elongation of the material are significantly higher than those of the comparative example, which proves that the optimization of the holding time plays a key role in the strength and plasticity of the material; (2) Compared with the comparative example, the embodiment adopts a moderate tempering temperature and an extended holding time, and the impact toughness of the material is greatly improved, indicating that reasonable control of the tempering temperature and time is helpful to improve the impact resistance of the material under harsh conditions; (3) The embodiment shows better material uniformity, while the comparative example has incomplete internal stress release due to insufficient holding time, resulting in poor cleanliness. This shows that extending the holding time helps to purify inclusions in steel, thereby improving the long-term stability of the material.

[0067] The embodiments described above are only descriptions of the preferred modes of the present invention, and are not intended to limit the scope of the present invention. Without departing from the design spirit of the present invention, various modifications and improvements made to the technical solutions of the present invention by ordinary technicians in this field should all fall within the protection scope determined by the claims of the present invention.

Claims

1. A heat treatment process for 25CrMoA round steel for sucker rod, characterized in that: The method comprises the following steps: (1) quenching: placing the rough-machined round steel blank sample of the sucker rod into a heating furnace, heating it to 865°C-900°C, keeping it warm for 50-70 minutes, and then quenching and water quenching; (2) tempering: placing the quenched sample into a heating furnace, heating it to 470-530°C, keeping it warm for 120-150 minutes, and then taking out the sample and cooling it in water; The chemical composition of the 25CrMoA round steel for the sucker rod is as follows: C 0.19-0.21%, Si 0.25-0.28%, Mn 0.76-0.79%, P≤0.016%, S≤0.012%, Cr 0.79-0.87%, Mo 0.18-0.22%, and the rest is iron and unavoidable impurities.

2. The heat treatment process of 25CrMoA round steel for sucker rod according to claim 1 is characterized in that: The chemical composition of the 25CrMoA round steel for the sucker rod is as follows: C 0.19%, Si 0.26%, Mn 0.78%, P 0.014%, S 0.009%, Cr 0.85%, Mo 0.20%, and the rest is iron and unavoidable impurities.

3. The heat treatment process of 25CrMoA round steel for sucker rod according to claim 1, characterized in that: The chemical composition of the 25CrMoA round steel for the sucker rod is as follows: C 0.20%, Si 0.28%, Mn 0.76%, P 0.015%, S 0.010%, Cr 0.87%, Mo 0.20%, and the rest is iron and inevitable impurities.

4. The heat treatment process of 25CrMoA round steel for sucker rod according to claim 1, characterized in that: The chemical composition of the 25CrMoA round steel for the sucker rod is as follows: C 0.21%, Si 0.25%, Mn 0.79%, P 0.015%, S 0.008%, Cr 0.79%, Mo 0.20%, and the rest is iron and inevitable impurities.

5. The heat treatment process of 25CrMoA round steel for sucker rod according to claim 2, characterized in that: Proceed as follows: (1) Quenching: Place the rough-machined round steel blank of the sucker rod into a heating furnace, heat it to 870°C, keep it warm for 50 minutes, and then quench it with water; (2) Tempering: Place the quenched sample into a heating furnace, heat to 485°C, keep warm for 120 min, then take out the sample and cool it in water.

6. The heat treatment process of 25CrMoA round steel for sucker rod according to claim 3, characterized in that: Proceed as follows: (1) Quenching: Place the rough-machined round steel blank of the sucker rod into a heating furnace, heat it to 890°C, keep it warm for 70 minutes, and then quench it with water; (2) Tempering: Place the quenched sample into a heating furnace, heat to 515°C, keep warm for 150 min, then take out the sample and cool it in water.

7. The heat treatment process of 25CrMoA round steel for sucker rod according to claim 4, characterized in that: Proceed as follows: (1) Quenching: Place the rough-machined round steel blank of the sucker rod into a heating furnace, heat it to 880°C, keep it warm for 60 minutes, and then quench it with water; (2) Tempering: Place the quenched sample in a heating furnace, heat to 500°C, keep warm for 130 minutes, then take out the sample and cool it in water.

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