Heat treatment process of round steel for sucker rod

Abstract

The invention discloses a heat treatment process of round steel for sucker rods, a used heat treatment sample is 30CrMoA round steel for sucker rods, and heat treatment is carried out according to the following steps: (1) direct quenching: heating the round steel to 850-870 DEG C to austenitize the material; the heating time is 50 to 70 minutes. Then quenching in water, wherein the quenching time is 10-15 seconds; and (2) self-tempering: taking out after quenching, and gradually cooling to room temperature through natural cooling without an additional heating process. The heat-treated sample is subjected to mechanical property inspection, and at normal temperature, the yield strength is larger than or equal to 735 MPa, the tensile strength is larger than or equal to 930 MPa, the ductility is larger than or equal to 12%, and the percentage reduction of area is larger than or equal to 50%; impact absorption KU2 is greater than or equal to 71J, and various non-metallic inclusions are less than or equal to 1.5 grades.

Description

Technical Field

[0001] The invention belongs to the technical field of manufacturing round steel for pumping rods, and in particular relates to a heat treatment process of 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 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, the corrosion resistance of round steel can be improved, and the long-term stability of pumping rods in harsh environments can be ensured. The traditional heat treatment method for 30CrMoA round steel for pumping rods is generally quenching at 880℃ and then tempering at 540℃. Through such a heat treatment process, 30CrMoA round steel for pumping rods can have good comprehensive mechanical properties. However, the traditional 880℃ quenching + 540℃ tempering process heat treatment method has the disadvantages of high energy consumption, long time consumption and high cost. In order to simplify the heat treatment process and save costs, the present invention adopts a direct quenching + self-tempering heat treatment process to replace the traditional 880℃ quenching and 540℃ tempering process, which can achieve the goal of simplifying the process and reducing costs. The steel is heated to 850-870℃, kept warm for 30-60min, quenched in water for 15-20s, and then the sample is taken out and self-tempered in the air using its own residual heat. Through this heat treatment process, the heat treatment cost of 30CrMoA round steel for sucker rods can be effectively reduced, the process steps can be simplified, and the production efficiency can be improved while maintaining the material properties, which is suitable for large-scale industrial production. Summary of the invention

[0003] The purpose of the present invention is to provide a heat treatment process for round steel for pumping rods, so that the round steel has good comprehensive mechanical properties, thereby significantly improving the overall life and safety of the round steel for pumping rods.

[0004] In order to solve the above technical problems, the present invention adopts the following technical solutions:

[0005] The present invention provides a heat treatment process for round steel for a pumping rod, comprising the following steps:

[0006] (1) Direct quenching: Heat the round steel to 850-870℃ to austenitize the material for 50-70min, then quench in water for 10-15s;

[0007] (2) Self-tempering: After quenching, the temperature gradually drops to room temperature through natural cooling without the need for additional heating.

[0008] Further, the following steps are included:

[0009] (1) Direct quenching: Heat the round steel to 850°C to austenitize the material for 50 minutes. Then quench in water for 12 seconds.

[0010] (2) Self-tempering: After quenching, take it out and gradually cool it to room temperature through natural cooling without the need for additional heating process.

[0011] Further, the following steps are included:

[0012] (1) Direct quenching: Heat the round steel to 870°C to austenitize the material for 70 minutes. Then quench in water for 15 seconds.

[0013] (2) Self-tempering: After quenching, take it out and gradually cool it to room temperature through natural cooling without the need for additional heating process.

[0014] Further, the following steps are included:

[0015] 1) Direct quenching: Heat the round steel to 860°C to austenitize the material for 60 minutes. Then quench in water for 10 seconds;

[0016] (2) Self-tempering: After quenching, take it out and gradually cool it to room temperature through natural cooling without the need for additional heating process.

[0017] Furthermore, the round steel for sucker rod is 30CrMoA round steel for sucker rod.

[0018] Compared with the prior art, the beneficial technical effects of the present invention are:

[0019] (1) Reduced costs: The number of heating times can be reduced. Self-tempering utilizes the residual heat inside the material, and no additional tempering furnace is required, which reduces energy consumption. No additional tempering equipment or multiple heating equipment is required, which reduces equipment costs and maintenance costs. (2) The traditional quenching + tempering process requires two heating steps and two processing steps. Direct quenching + self-tempering only requires one heating to complete quenching and tempering, which significantly simplifies the process flow and improves production efficiency. (3) Since the internal cooling and self-tempering treatments are performed separately, the brittle fracture problem caused by excessive quenching is avoided, ensuring better overall strength and impact resistance of the sucker rod. DETAILED DESCRIPTION

[0020] The heat treatment process of round steel for pumping rods of the present invention determines a set of heat treatment systems that can ensure the quality of steel; it can effectively reduce the heat treatment cost of 30CrMoA round steel for pumping rods, simplify the process steps, and improve production efficiency under the premise of improving the mechanical properties of the material and reducing inclusions in the steel.

[0021] Embodiment 1:

[0022] The heat treatment process of the present invention is performed on a 30CrMoA round steel bar for a pumping rod, and is performed in the following steps:

[0023] (1) Direct quenching: Heat the round steel to 850°C to austenitize the material. The heating time is 50 minutes. Then quench in water for 12 seconds.

[0024] (2) Self-tempering: The quenched sample is taken out and gradually cooled to room temperature through natural cooling without the need for additional heating process.

[0025] Embodiment 2:

[0026] The heat treatment process of the present invention is performed on a 30CrMoA round steel bar for a pumping rod, and is performed in the following steps:

[0027] (1) Direct quenching: Heat the round steel to 870°C to austenitize the material. The heating time is 70 minutes. Then quench in water for 15 seconds.

[0028] (2) Self-tempering: The quenched sample is taken out and gradually cooled to room temperature through natural cooling without the need for additional heating process.

[0029] Embodiment 3:

[0030] The heat treatment process of the present invention is performed on a 30CrMoA round steel bar for a pumping rod, and is performed in the following steps:

[0031] (1) Direct quenching: Heat the round steel to 860°C to austenitize the material. The heating time is 60 minutes. Then quench in water for 10 seconds.

[0032] (2) Self-tempering: The quenched sample is taken out and gradually cooled to room temperature through natural cooling without the need for additional heating process.

[0033] Comparative Example 1:

[0034] The heat treatment process of the present invention is performed on a 30CrMoA round steel bar for a pumping rod, and is performed in the following steps:

[0035] (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 50 minutes, and then quench it with water;

[0036] (2) Tempering: Place the quenched sample in a heating furnace, heat to 550°C, keep warm for 120 minutes, then take out the sample and cool it in air.

[0037] Comparative Example 2:

[0038] The heat treatment process of the present invention is performed on a 30CrMoA round steel bar for a pumping rod, and is performed in the following steps:

[0039] (1) Quenching: Place the rough-machined round steel blank of the sucker rod into a heating furnace, heat it to 900°C, keep it warm for 50 minutes, and then quench it with water;

[0040] (2) Tempering: Place the quenched sample into a heating furnace, heat it to 535°C, keep it warm for 100 min, then take out the sample and cool it in air.

[0041] Comparative Example 3:

[0042] The heat treatment process of the present invention is performed on a 30CrMoA round steel bar for a pumping rod, and is performed in the following steps:

[0043] 1) Quenching: Put the rough-machined round steel blank of the sucker rod into the heating furnace, heat it to 880℃, keep it warm for 50min, and then quench it with water;

[0044] (2) Tempering: Place the quenched sample in a heating furnace, heat to 540°C, keep warm for 130 min, then take out the sample and cool it in air.

[0045] After the heat treatment, the samples were finely processed and various performance tests were carried out. The test results are shown in Table 1, Table 2 and Table 3. It can be seen from Table 1, Table 2 and Table 3 that all performance indicators are higher than the index requirements, and the performance of the samples after heat treatment is qualified.

[0046] Table 1 Mechanical properties at room temperature after heat treatment

[0047]

[0048] Table 3 Impact toughness after heat treatment

[0049]

[0050]

[0051] Table 4 Non-metallic inclusions after heat treatment

[0052]

[0053] 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 round steel for sucker rods, characterized in that: The steps include: (1) Direct quenching: Heat the round steel to 850-870℃ to austenitize the material for 50-70min, then quench in water for 10-15s; (2) Self-tempering: After quenching, the temperature gradually drops to room temperature through natural cooling without the need for additional heating.

2. The heat treatment process of round steel for sucker rod according to claim 1, characterized in that: The steps include: (1) Direct quenching: Heat the round steel to 850°C to austenitize the material for 50 minutes. Then quench in water for 12 seconds. (2) Self-tempering: After quenching, take it out and gradually cool it to room temperature through natural cooling without the need for additional heating process.

3. The heat treatment process of round steel for sucker rod according to claim 1, characterized in that: The steps include: (1) Direct quenching: Heat the round steel to 870°C to austenitize the material for 70 minutes. Then quench in water for 15 seconds. (2) Self-tempering: After quenching, take it out and gradually cool it to room temperature through natural cooling without the need for additional heating process.

4. The heat treatment process for round steel for sucker rod according to claim 1, characterized in that: The steps include: 1) Direct quenching: Heat the round steel to 860°C to austenitize the material for 60 minutes. Then quench in water for 10 seconds; (2) Self-tempering: After quenching, take it out and gradually cool it to room temperature through natural cooling without the need for additional heating process.

5. The heat treatment process for round steel for sucker rod according to claim 1, characterized in that: The round steel for the sucker rod is 30CrMoA round steel for the sucker rod.

Images