Preparation method of sucker rod based on rare earth material reinforcement

Abstract

The preparation method comprises the steps that raw materials are prepared, specifically, high-quality carbon steel is selected as a basic raw material, and chemical components of the high-quality carbon steel are strictly controlled within a specific range; wherein the carbon content is controlled to be 0.30%-0.45%, the silicon content is kept to be 0.20%-0.35%, the manganese content is 0.60%-0.80%, the phosphorus content and the sulfur content are strictly limited to be smaller than or equal to 0.035%, and in addition, an additive rich in rare earth elements of cerium and lanthanum is prepared; smelting in a converter; refining outside a furnace; preparing a continuous casting blank; rolling processing; according to the heat treatment method, the strength and the corrosion resistance of the sucker rod are remarkably improved, the fatigue life of the sucker rod is remarkably prolonged, the energy consumption and the cost in the production process are reduced, the production efficiency is improved, and a sucker rod product with better performance and higher cost performance is provided for the oil exploitation industry.

Description

Technical Field

[0001] The invention belongs to the technical field of sucker rod production, and in particular relates to a preparation method of a sucker rod reinforced with rare earth materials. Background Art

[0002] In the process of oil extraction, the performance of the sucker rod, as a key component connecting the oil pump and the pumping unit, directly affects the efficiency and cost of the extraction operation. Traditional sucker rods are mainly made of ordinary steel. After being subjected to alternating loads and erosion by harsh downhole environments for a long time, they are prone to problems such as strength loss and fatigue fracture. For example, in high-temperature, high-salt, and high-sulfur oil wells, the corrosion rate of ordinary sucker rods is accelerated, resulting in a significant shortening of their service life. According to relevant statistics, under some harsh working conditions, the average service life of ordinary sucker rods is only 2-3 years. Frequent replacement operations not only consume a lot of manpower, material and financial resources, but also cause oil wells to stop production, affecting crude oil production.

[0003] At present, the common production process of sucker rods is mainly based on electric furnace smelting. Although electric furnace smelting can guarantee the quality of molten steel to a certain extent, it has disadvantages such as high energy consumption and long production cycle. Taking the production of 1 ton of sucker rods as an example, the energy consumption of electric furnace smelting is about 800-1000 kWh, and the entire production cycle from raw material input to finished product output usually takes 3-5 days. In addition, in the process of introducing rare earth elements into the production of sucker rods, the existing technology makes it difficult to achieve uniform distribution of rare earth elements in molten steel, resulting in unstable product performance and failure to give full play to the optimization effect of rare earth elements on steel performance. Summary of the invention

[0004] The purpose of the present invention is to provide a method for preparing a sucker rod reinforced with rare earth materials, which not only significantly improves the strength, corrosion resistance and fatigue life of the sucker rod, but also reduces energy consumption and cost in the production process, improves production efficiency, and provides the oil extraction industry with sucker rod products with better performance and higher cost performance.

[0005] In order to solve the above technical problems, the present invention adopts the following technical solutions:

[0006] The present invention provides a method for preparing a sucker rod reinforced with rare earth materials, comprising:

[0007] Raw material preparation: Select high-quality carbon steel as the basic raw material, and its chemical composition is strictly controlled within a specific range; among which: the carbon content is controlled between 0.30%-0.45%, the silicon content is maintained at 0.20%-0.35%, the manganese content is 0.60%-0.80%, and the phosphorus and sulfur contents are strictly limited to ≤0.035%. In addition, additives rich in cerium and lanthanum rare earth elements are prepared;

[0008] Converter smelting: Add the prepared high-quality carbon steel raw materials into the converter to start the smelting process. First, blow an appropriate amount of oxygen into the converter and use the heat generated by the chemical reaction between oxygen and elements such as carbon to quickly heat up and melt the steel; during the smelting process, accurately control the temperature in the converter between 1500-1600℃. Too high or too low temperature will affect the quality of the molten steel and the effect of adding rare earth elements; when the temperature of the molten steel reaches 1550 plus or minus 20℃ and the steel is fully melted, add rare earth additives according to the predetermined proportion; to ensure that the rare earth elements can be evenly integrated into the molten steel, after adding the rare earth additives, use a combination of mechanical stirring and air blowing stirring, and continue stirring for 10-15 minutes; during the stirring process, closely monitor the changes in the composition of the molten steel, and adjust the amount of rare earth elements added in real time through spectral analysis to ensure that the content of rare earth elements in the molten steel reaches the expected target;

[0009] Refining outside the furnace: Although some impurities have been initially removed from the molten steel after converter smelting, further refining is still required to meet higher quality requirements; the molten steel is transferred to the refining equipment outside the furnace: LF refining furnace or VD vacuum refining furnace; in the refining process outside the furnace, argon stirring and adding refining agents are mainly used to further remove inclusions and harmful gases in the molten steel and adjust the chemical composition of the molten steel; by precisely controlling the refining time and temperature: the refining time is 30-60 minutes, and the temperature is controlled at 1500-1550℃, the purity and chemical composition uniformity of the molten steel can meet the standards for producing high-quality sucker rods;

[0010] Preparation of continuous casting billet: The molten steel refined outside the furnace enters the continuous casting process; during the continuous casting process, the pulling speed and cooling intensity are strictly controlled: the pulling speed is usually controlled between 2.0-2.1m / min, and the cooling intensity is adjusted according to the specifications and steel type of the billet. Generally, the secondary cooling method is adopted to control the cooling water volume and cooling time to make the billet evenly cooled in the crystallizer to form a dense and uniform organizational structure; at the same time, the electromagnetic stirring technology is used to further improve the internal quality of the billet, reduce segregation, and ensure that the quality of the continuous casting billet meets the rolling requirements; finally, the square billet with a side length of 150mm is made into a continuous casting billet, providing high-quality billets for subsequent rolling processing;

[0011] Rolling process: The continuous casting billet is heated to a high temperature of 1100-1200℃ to make it have good plasticity and machinability; then, the heated continuous casting billet is sent to the rolling mill for multiple rolling; during the rolling process, the rolling passes and reduction are carefully designed according to the final specifications and performance requirements of the pumping rod, and the rolling passes are 8-12 passes. By gradually reducing the roller spacing, the cross-sectional size of the continuous casting billet is gradually reduced, and finally rolled into the required specifications of the pumping rod round steel; after each rolling pass, the size, shape and surface quality of the billet are tested, and the rolling parameters are adjusted in time to ensure the stable quality of the billet; at the same time, the online temperature control technology is used to control the temperature of the billet during the rolling process to avoid organizational defects and performance degradation caused by too high or too low temperature;

[0012] Heat treatment: The rolled sucker rod round steel is heat treated. The heat treatment process includes two steps: quenching and tempering. The quenching temperature is controlled between 850-900℃ and the holding time is 30-40 minutes to fully austenitize the internal structure of the billet. Then, the billet is quickly placed in a quenching medium for cooling. The quenching medium can be water, oil or other special quenching liquids. The cooling rate is adjusted according to the steel type and billet size to obtain an ideal martensitic structure. The tempering temperature is controlled between 550-600℃ and the holding time is 60-90 minutes.

[0013] Furthermore, it also includes: surface treatment: performing surface treatment on the heat-treated sucker rod.

[0014] Furthermore, the surface treatment adopts hot-dip galvanizing or nickel plating process: the hot-dip galvanizing process is to immerse the sucker rod in molten zinc liquid to form a dense zinc layer on the surface of the sucker rod. The thickness of the zinc layer is generally controlled between 80-120μm, which can effectively isolate the contact between the external corrosive medium and the sucker rod matrix; the nickel plating process is to electroplating a nickel layer on the surface of the sucker rod. The nickel layer thickness is 50-80μm. The nickel layer has good corrosion resistance and wear resistance, and can increase the service life of the sucker rod in harsh environments.

[0015] Furthermore, the raw material preparation is specifically as follows: prepare 1000kg of high-quality carbon steel, whose chemical composition in mass percentage is: C 0.35%, Si 0.25%, Mn 0.65%, P≤0.035%, S≤0.035%, prepare 5kg of rare earth additives, wherein the cerium content is 40%, the lanthanum content is 30%, and the content of other rare earth elements is 30%.

[0016] Furthermore, the raw material preparation is specifically as follows: prepare 1500kg of high-quality carbon steel, whose chemical composition in mass percentage is: C 0.40%, Si 0.30%, Mn 0.70%, P≤0.035%, S≤0.035%, prepare 8kg of rare earth additives, wherein the cerium content is 45%, the lanthanum content is 35%, and the content of other rare earth elements is 20%.

[0017] Furthermore, the rare earth sucker rod produced by the process of the present invention has a yield strength increased by 20%-30%, a tensile strength increased by 15%-25%, and an impact toughness increased by 30%-50% compared with traditional sucker rods, can withstand greater loads, and reduces the risk of breakage during use.

[0018] Furthermore, the corrosion rate of the sucker rod produced by the invention is reduced by more than 50% compared with the traditional sucker rod.

[0019] Furthermore, the energy consumption of producing 1 ton of sucker rod using the converter rolling process is reduced by 200-300 kWh compared to the electric furnace smelting process.

[0020] Compared with the prior art, the beneficial technical effects of the present invention are:

[0021] Significant performance improvement: By precisely adding rare earth additives during the converter smelting process and optimizing the process parameters, the rare earth elements are evenly distributed in the molten steel, effectively refining the grains and improving the internal structure of the sucker rod. According to tests, the rare earth sucker rod produced by the process of the present invention has a yield strength increased by 20%-30%, a tensile strength increased by 15%-25%, and an impact toughness increased by 30%-50% compared with the traditional sucker rod. It can withstand greater loads and reduce the risk of breakage during use.

[0022] Improved corrosion resistance: The addition of rare earth elements and the application of surface treatment technology greatly improve the corrosion resistance of the sucker rod. In the simulated high temperature, high salt, high sulfur oil well environment, the corrosion rate of the sucker rod produced by the present invention is reduced by more than 50% compared with the traditional sucker rod, which effectively extends the service life of the sucker rod, reduces the number of replacements, and reduces the mining cost.

[0023] Improved production efficiency: Compared with the traditional electric furnace smelting process, the converter rolling process has the advantages of short production cycle and high production efficiency. Using the process of the present invention, the time for producing 1 ton of sucker rods can be shortened to 2-3 days, and the production efficiency is increased by 30%-50%, which can meet the large market demand for sucker rods.

[0024] Reduced energy consumption: Converter smelting uses its own chemical reaction heat to reduce external energy consumption. According to calculations, the energy consumption of producing 1 ton of sucker rods using the converter rolling process is reduced by 200-300 kWh compared to the electric furnace smelting process, which meets the environmental protection requirements of energy conservation and emission reduction and has significant economic and environmental benefits. DETAILED DESCRIPTION

[0025] Embodiment 1:

[0026] Raw material preparation: prepare 1000kg of high-quality carbon steel, whose chemical composition (mass fraction) is: C 0.35%, Si 0.25%, Mn 0.65%, P≤0.035%, S≤0.035%, prepare 5kg of rare earth additives, of which the cerium content is 40%, the lanthanum content is 30%, and the content of other rare earth elements is 30%.

[0027] Converter smelting: Add high-quality carbon steel to the converter, heat it to 1550℃, introduce an appropriate amount of oxygen for smelting, and when the molten steel is fully melted, add rare earth additives, and stir and smelt for 12 minutes by combining mechanical stirring and air blowing stirring. During the stirring process, perform a spectral analysis of the molten steel every 3 minutes, and fine-tune the amount of rare earth additives added based on the analysis results to ensure that the content of rare earth elements in the molten steel is uniform and in line with expectations.

[0028] Refining outside the furnace: The molten steel after melting in the converter is transferred to the LF refining furnace and refined for 30 minutes by stirring with argon. During the refining process, refining agents are added in stages. According to the changes in the content of impurities such as sulfur and phosphorus in the molten steel, the amount and time of refining agents are adjusted to reduce the impurity content in the molten steel to within the specified range.

[0029] Preparation of continuous casting billet: The refined molten steel is continuously cast, the casting speed is controlled at 2.1m / min, and the secondary cooling method is adopted. An electromagnetic stirring device is installed in the crystallizer to make a square billet with a side length of 150mm. During the continuous casting process, the surface quality and internal defects of the billet are monitored in real time, and the quality of the billet is ensured by adjusting the cooling water volume and electromagnetic stirring parameters.

[0030] Rolling process: The continuous casting billet is heated to 1150℃ and sent to the rolling mill for 8 passes of rolling. Before each rolling pass, the roller spacing and rolling speed are adjusted according to the billet size and performance test results after the previous rolling. During the rolling process, online temperature control technology is used to ensure that the billet temperature is always kept within the appropriate range, and finally rolled into a pumping rod round steel with a diameter of 25mm.

[0031] Heat treatment: The sucker rod blank is quenched at 880°C, kept at this temperature for 35 minutes, and then quickly placed in oil for cooling; then tempered at 580°C for 75 minutes. During the heat treatment process, a thermocouple is used to monitor the temperature change of the blank in real time to ensure the accurate execution of the heat treatment process.

[0032] Surface treatment: The heat-treated sucker rod is surface treated by hot-dip galvanizing process, and the thickness of the galvanized layer is 80μm. During the galvanizing process, the parameters such as zinc liquid temperature, immersion time and removal speed are controlled to ensure that the galvanized layer is uniform and dense.

[0033] Embodiment 2:

[0034] Raw material preparation: prepare 1500kg of high-quality carbon steel, whose chemical composition (mass fraction) is: C 0.40%, Si 0.30%, Mn 0.70%, P≤0.035%, S≤0.035%, prepare 8kg of rare earth additives, of which the cerium content is 45%, the lanthanum content is 35%, and the content of other rare earth elements is 20%.

[0035] Converter smelting: Add high-quality carbon steel to the converter, heat it to 1580℃, introduce an appropriate amount of oxygen for smelting, and when the molten steel is fully melted, add rare earth additives and stir and smelt for 13 minutes. During the stirring process, advanced testing equipment is used to monitor the composition and temperature of the molten steel in real time to ensure that the rare earth elements are evenly integrated into the molten steel.

[0036] Refining outside the furnace: The molten steel after converter melting is transferred to the VD vacuum refining furnace, stirred with argon gas, and refined for 35 minutes. In a vacuum environment, harmful gases and inclusions in the molten steel are further removed to improve the purity of the molten steel.

[0037] Preparation of continuous casting billet: The refined molten steel is continuously cast, the casting speed is controlled at 2.1m / min, and the secondary cooling method is adopted to make a square billet continuous casting billet with a side length of 150mm. During the continuous casting process, the billet is subjected to ultrasonic flaw detection to timely discover and deal with internal defects.

[0038] Rolling process: The continuous casting billet is heated to 1180℃ and sent to the rolling mill for 10 passes of rolling. During the rolling process, according to the performance requirements of the pumping rod, the rolling passes and the reduction amount are optimized, and the advanced roll cooling technology is used to ensure the service life of the roll and the rolling quality, and finally the pumping rod round steel with a diameter of 30mm is rolled.

[0039] Heat treatment: The sucker rod blank is quenched at 890℃, kept at this temperature for 38 minutes and then rapidly cooled; then tempered at 590℃ for 80 minutes. During the heat treatment process, the heating speed, holding time and cooling speed are strictly controlled to ensure that the sucker rod blank obtains the ideal organizational structure and performance.

[0040] Surface treatment: The heat-treated sucker rod is surface treated with nickel plating, and the thickness of the nickel plating layer is 50μm. During the nickel plating process, the quality and performance of the nickel plating layer are guaranteed by adjusting the composition of the electroplating solution and current density and other parameters.

[0041] 1. Composition and content of finished product of the embodiment

[0042] Example 1

[0043] Chemical composition: C 0.35%, Si 0.25%, Mn 0.65%, P≤0.035%, S≤0.035%, rare earth lanthanum and cerium are 30ppm.

[0044] Example 2

[0045] Chemical composition: C 0.38%, Si 0.28%, Mn 0.70%, P≤0.030%, S≤0.030%, rare earth lanthanum and cerium are 40ppm.

[0046] 2. Comparative Example Ingredients

[0047] Traditional sucker rod (comparative example)

[0048] Chemical composition: C 0.40%, Si 0.20%, Mn 0.60%, P≤0.040%, S≤0.040%, no rare earth added.

[0049] 3. Mechanical properties and comparison

[0050]

[0051]

[0052] It can be clearly seen from the above data that in terms of tensile strength, Example 1 reaches 950MPa, and Example 2 is as high as 980MPa, while the traditional sucker rod is only 750MPa, which is a significant improvement. In terms of impact toughness, Example 1 is 80J / cm 2 , Example 2 is 85 J / cm 2 , much higher than the 60J / cm of traditional sucker rods 2, indicating that the rare earth sucker rod performs better in resisting impact. In terms of corrosion rate, Example 1 is 0.05mm / a, Example 2 is 0.04mm / a, and the traditional sucker rod is 0.12mm / a. The corrosion resistance of the rare earth sucker rod is obvious. In terms of service life, Example 1 can reach 8 years, Example 2 is 9 years, and the traditional sucker rod is only 5 years. It fully proves that the rare earth sucker rod produced by the process of the present invention is significantly superior to the traditional sucker rod in strength, corrosion resistance and service life, which effectively verifies the feasibility and superiority of the process of the present invention.

[0053] The rare earth sucker rods produced by Example 1 and Example 2 were subjected to comprehensive performance tests, including tensile tests, impact tests, corrosion tests, etc. The results showed that their strength, corrosion resistance and service life were significantly better than those of traditional sucker rods, fully verifying the feasibility and superiority of the process of the present invention.

Claims

1. A method for preparing a sucker rod reinforced with rare earth materials, characterized in that: include: Raw material preparation: Select high-quality carbon steel as the basic raw material, and its chemical composition is strictly controlled within a specific range; among which: the carbon content is controlled between 0.30%-0.45%, the silicon content is maintained at 0.20%-0.35%, the manganese content is 0.60%-0.80%, and the phosphorus and sulfur contents are strictly limited to ≤0.035%. In addition, additives rich in cerium and lanthanum rare earth elements are prepared; Converter smelting: Add the prepared high-quality carbon steel raw materials into the converter to start the smelting process. First, blow an appropriate amount of oxygen into the converter and use the heat generated by the chemical reaction between oxygen and elements such as carbon to quickly heat up and melt the steel; during the smelting process, accurately control the temperature in the converter between 1500-1600℃. Too high or too low temperature will affect the quality of the molten steel and the effect of adding rare earth elements; when the temperature of the molten steel reaches 1550 plus or minus 20℃ and the steel is fully melted, add rare earth additives according to the predetermined proportion; to ensure that the rare earth elements can be evenly integrated into the molten steel, after adding the rare earth additives, use a combination of mechanical stirring and air blowing stirring, and continue stirring for 10-15 minutes; during the stirring process, closely monitor the changes in the composition of the molten steel, and adjust the amount of rare earth elements added in real time through spectral analysis to ensure that the content of rare earth elements in the molten steel reaches the expected target; Refining outside the furnace: Although some impurities have been initially removed from the molten steel after converter smelting, further refining is still required to meet higher quality requirements; the molten steel is transferred to the refining equipment outside the furnace: LF refining furnace or VD vacuum refining furnace; in the refining process outside the furnace, argon stirring and adding refining agents are mainly used to further remove inclusions and harmful gases in the molten steel and adjust the chemical composition of the molten steel; by precisely controlling the refining time and temperature: the refining time is 30-60 minutes, and the temperature is controlled at 1500-1550℃, the purity and chemical composition uniformity of the molten steel can meet the standards for producing high-quality sucker rods; Preparation of continuous casting billet: The molten steel refined outside the furnace enters the continuous casting process; during the continuous casting process, the pulling speed and cooling intensity are strictly controlled: the pulling speed is usually controlled between 2.0-2.1m / min, and the cooling intensity is adjusted according to the specifications and steel type of the billet. Generally, the secondary cooling method is adopted to control the cooling water volume and cooling time to make the billet evenly cooled in the crystallizer to form a dense and uniform organizational structure; at the same time, the electromagnetic stirring technology is used to further improve the internal quality of the billet, reduce segregation, and ensure that the quality of the continuous casting billet meets the rolling requirements; finally, the square billet with a side length of 150mm is made into a continuous casting billet, providing high-quality billets for subsequent rolling processing; Rolling process: The continuous casting billet is heated to a high temperature of 1100-1200℃ to make it have good plasticity and machinability; then, the heated continuous casting billet is sent to the rolling mill for multiple rolling; during the rolling process, the rolling passes and reduction are carefully designed according to the final specifications and performance requirements of the pumping rod, and the rolling passes are 8-12 passes. By gradually reducing the roller spacing, the cross-sectional size of the continuous casting billet is gradually reduced, and finally rolled into the required specifications of the pumping rod round steel; after each rolling pass, the size, shape and surface quality of the billet are tested, and the rolling parameters are adjusted in time to ensure the stable quality of the billet; at the same time, the online temperature control technology is used to control the temperature of the billet during the rolling process to avoid organizational defects and performance degradation caused by too high or too low temperature; Heat treatment: The rolled sucker rod round steel is heat treated. The heat treatment process includes two steps: quenching and tempering. The quenching temperature is controlled between 850-900℃ and the holding time is 30-40 minutes to fully austenitize the internal structure of the billet. Then, the billet is quickly placed in a quenching medium for cooling. The quenching medium can be water, oil or other special quenching liquids. The cooling rate is adjusted according to the steel type and billet size to obtain an ideal martensitic structure. The tempering temperature is controlled between 550-600℃ and the holding time is 60-90 minutes.

2. The method for preparing a sucker rod reinforced with rare earth materials according to claim 1, characterized in that: Also includes: Surface treatment: Surface treatment is performed on the heat-treated sucker rod.

3. The method for preparing a sucker rod reinforced with rare earth materials according to claim 2, characterized in that: The surface treatment adopts hot-dip galvanizing or nickel plating process: the hot-dip galvanizing process is to immerse the sucker rod in molten zinc liquid to form a dense zinc layer on the surface of the sucker rod. The thickness of the zinc layer is generally controlled between 80-120μm, which can effectively isolate the contact between the external corrosive medium and the sucker rod substrate; the nickel plating process is to plate a nickel layer on the surface of the sucker rod by electroplating. The nickel layer thickness is 50-80μm. The nickel layer has good corrosion resistance and wear resistance, and can increase the service life of the sucker rod in harsh environments.

4. The method for preparing a sucker rod reinforced with rare earth materials according to claim 1, characterized in that: The raw material preparation is specifically as follows: prepare 1000kg of high-quality carbon steel, whose chemical composition by mass percentage is: C 0.35%, Si0.25%, Mn 0.65%, P≤0.035%, S≤0.035%, prepare 5kg of rare earth additives, wherein the cerium content is 40%, the lanthanum content is 30%, and the content of other rare earth elements is 30%.

5. The method for preparing a sucker rod reinforced with rare earth materials according to claim 1, characterized in that: The raw material preparation is specifically as follows: 1500kg of high-quality carbon steel, whose chemical composition by mass percentage is: C 0.40%, Si0.30%, Mn 0.70%, P≤0.035%, S≤0.035%, and 8kg of rare earth additives, wherein the cerium content is 45%, the lanthanum content is 35%, and the content of other rare earth elements is 20%.

6. The method for preparing a sucker rod reinforced with rare earth materials according to claim 1, characterized in that: The rare earth sucker rod produced by the process of the present invention has a yield strength increased by 20%-30%, a tensile strength increased by 15%-25%, and an impact toughness increased by 30%-50% compared with traditional sucker rods. It can withstand a larger load and reduces the risk of breakage during use.

7. The method for preparing a sucker rod reinforced with rare earth materials according to claim 1, characterized in that: The corrosion rate of the sucker rod produced by the invention is reduced by more than 50% compared with the traditional sucker rod.

8. The method for preparing a sucker rod reinforced with rare earth materials according to claim 1, characterized in that: The energy consumption of producing 1 ton of sucker rod using the converter rolling process is reduced by 200-300 kWh compared to the electric furnace smelting process.

Images