Alloy material for high-strength pressure-resistant drill rod and preparation method of alloy material

Abstract

The invention relates to the technical field of alloy materials, in particular to an alloy material for a high-strength pressure-resistant drill rod and a preparation method of the alloy material. The material is prepared from matrix alloy powder and modified composite precursor powder through ball-milling mixing and hot isostatic pressing, wherein the modified composite precursor is prepared by taking graphene oxide as a carrier through a dual confinement strategy of vanadium acetylacetonate interlayer intercalation in-situ nitridation and secondary chelation of vanadium ions on a polydopamine interface, so that Ostwald ripening of a precipitated phase at a high temperature is effectively inhibited, and the interface bonding force is greatly enhanced. The yield strength attenuation rate of the obtained material at the high temperature of 180 DEG C is lower than 2.8%, the strength and toughness are synergistically improved, and the material is particularly suitable for manufacturing drill rods in the high-temperature and high-pressure environments of deep wells and ultra-deep wells.

Description

A high-strength pressure-resistant alloy material for drill pipes and its preparation method Technical Field

[0001] This invention relates to the field of alloy materials technology, specifically to a high-strength, pressure-resistant alloy material for drill pipes and its preparation method. Background Technology

[0002] As global oil and gas exploration expands into deeper, ultra-deeper formations and more complex geological environments, drilling depths are constantly breaking records, and downhole operating conditions are becoming increasingly harsh. Drill pipe, as the hub connecting surface equipment and bottom-hole drilling tools, must withstand complex alternating loads such as tension, torsion, and bending during its service life. Especially in deep well operations, bottom-hole temperatures often exceed 175°C, and even reach over 200°C. Under such high-temperature and high-pressure environments, traditional high-strength low-alloy steel drill pipe materials such as S135 and G105 face severe challenges: on the one hand, the increased thermal vibration of the matrix lattice and reduced dislocation slip resistance lead to a significant thermal decay of yield strength with increasing temperature, seriously affecting the safety of the drill string; on the other hand, second-phase particles (such as carbides and nitrides) introduced to improve strength are prone to Ostwald ripening at high temperatures, i.e., small particles dissolve and large particles engulf and grow, causing the dispersion strengthening effect to fail and the material to soften rapidly.

[0003] To overcome these problems, existing technologies often attempt to introduce novel nano-reinforcing phases such as graphene and carbon nanotubes. However, these nanomaterials have enormous specific surface areas and extremely high surface energies, making them highly susceptible to irreversible aggregation in steel matrices, forming microscopic crack initiation sites. Although ball milling or simple surfactant modification can improve dispersibility to some extent, this physical or weak chemical bond is extremely fragile under high temperature and high stress. The lack of interlayer support in graphene makes it prone to recombination under hot pressing, losing its high modulus properties; simultaneously, the lack of strong chemical bonds between the reinforcing phase and the metal matrix results in a mechanically interlocked interface, which is prone to decoupling and slippage at high temperatures, leading to load transfer failure.

[0004] Therefore, how to construct an interface structure with high-temperature thermal stability while ensuring the monodispersity of the nano-reinforcing phase, suppressing the coarsening of the reinforcing phase, and solving the problem of poor interfacial bonding is a key technical bottleneck that urgently needs to be solved in the preparation of high-performance deep well drill pipe materials. Summary of the Invention

[0005] In view of this, the purpose of this invention is to propose a high-strength pressure-resistant alloy material for drill pipe and its preparation method, so as to solve the problem of severe attenuation of high-temperature yield strength and imbalance of strength and toughness caused by coarsening of reinforcing phase in deep well drill pipe materials.

[0006] To achieve the above objectives, the present invention provides a high-strength pressure-resistant drill pipe alloy material, which is obtained by mixing, grinding, and sintering a matrix alloy powder and a modified composite precursor powder.

[0007] The modified composite precursor powder is made from monolayer graphene oxide powder. After vanadium acetylacetonate intercalation and solvothermal reduction to form intercalated reduced graphene oxide composite powder, a polydopamine active layer is constructed on its surface in tris(hydroxymethyl)aminomethane buffer using the auto-oxidative polymerization reaction of dopamine hydrochloride. The modified precursor powder is formed by the coordination chelation of vanadium trichloride by this layer.

[0008] Preferably, the weight percentage of the matrix alloy powder and the modified composite precursor powder is 99.0%-99.5%:0.5%-1.0%.

[0009] Preferably, the weight percentage of each element in the matrix alloy powder is: carbon (C) 0.28%, silicon (Si) 0.3%, manganese (Mn) 1.5%, phosphorus (P) <0.025%, sulfur (S) <0.025%, chromium (Cr) 1.2%, nickel (Ni) 0.035%, copper (Cu) 0.3%, vanadium (V) 0.1%, and the balance is iron (Fe).

[0010] Preferably, the ratio of the single-layer graphene oxide powder, vanadium acetylacetonate, and ethylenediamine is 400-600 mg: 2.5-3.5 g: 8-12 mL.

[0011] Preferably, the ratio of the intercalated reduced graphene oxide composite powder, dopamine hydrochloride, and vanadium trichloride aqueous solution is 400-600mg:800-1200mg:15-25mL.

[0012] Preferably, the single-layer graphene oxide powder sheet has a diameter of 0.5-5 μm and a thickness of 0.8-1.2 nm.

[0013] Preferably, the reaction temperature of the solvothermal reduction is 170-190℃, and the reaction time is 10-14h.

[0014] Preferably, the molar concentration of the vanadium trichloride aqueous solution is 0.1 mol / L.

[0015] Preferably, the concentration of the trihydroxymethylaminomethane buffer solution is 8-12 mM.

[0016] Preferably, the matrix alloy powder is prepared by vacuum induction melting gas atomization method.

[0017] Preferably, the vacuum induction melting gas atomization method is carried out in an argon atmosphere, and the heating temperature is 1600℃.

[0018] Preferably, the atomization pressure of the vacuum induction melting gas atomization method is 4.5 MPa, and the atomizing gas is high-purity nitrogen.

[0019] Preferably, the particle size of the matrix alloy powder is 15-53 μm.

[0020] Furthermore, the present invention also provides a method for preparing a high-strength pressure-resistant drill pipe alloy material, comprising the following steps: mixing and grinding a matrix alloy powder and a modified composite precursor powder evenly, then loading the mixture into a mold for hot isostatic pressing, and after cooling, performing a tempering heat treatment to obtain the high-strength pressure-resistant drill pipe alloy material.

[0021] Preferably, the grinding is carried out under argon protection, with a rotation speed of 280-320 r / min and a ball milling time of 1.5-2.5 h.

[0022] Preferably, the filling process of the mold is carried out in conjunction with a high-frequency mechanical vibration table (frequency 50-60Hz).

[0023] Preferably, the hot isostatic pressing uses argon as the pressure transmission medium. The temperature is first raised to 800-850°C at a rate of 10-15°C / min, and the pressure is maintained at 80MPa for 30-60min. Then, the temperature is raised to 1100-1200°C at a rate of 5-8°C / min, and the pressure is maintained at 120MPa for 3h.

[0024] Preferably, the quenching and tempering heat treatment process involves austenitizing water quenching at 900-940℃ for 50-70 minutes, followed by high-temperature tempering at 580-620℃ for 1.5-2.5 hours.

[0025] The beneficial effects of this invention are as follows: This invention employs a unique dual confinement strategy of in-situ nitridation of vanadium acetylacetone interlayers and secondary chelation of vanadium ions at a polydopamine biomimetic interface, which is mainly reflected in the following aspects: First, this invention utilizes the intercalation effect of vanadium acetylacetone molecules and subsequent solvothermal reactions to generate nano-vanadium nitride hard support phases in situ between graphene oxide layers. This effectively overcomes the interlayer collapse and recombination problems caused by van der Waals forces during subsequent high-temperature sintering and service of graphene, maximizing the preservation of the high aspect ratio and high strength of the reinforcing phase. The elastic modulus provides an extremely stable high-temperature skeletal support for the matrix, significantly reducing the thermal decay of the material's yield strength at high temperatures. Secondly, this invention constructs a flexible interface layer rich in vanadium carbonitride quantum dots in situ on the surface of the reinforcing phase through biomimetic modification with polydopamine and secondary vanadium ion chelation. On the one hand, the excellent wettability of polydopamine improves the dispersion uniformity of the reinforcing phase in the steel matrix; on the other hand, the in-situ generated ultrafine vanadium carbonitride quantum dots act as powerful grain boundary pinning particles at high temperatures, hindering grain growth and dislocation climb. It also effectively suppresses the long-range diffusion of vanadium atoms at high temperatures, doubly blocking the Ostwald ripening process of the precipitated phase from both thermodynamic and kinetic perspectives, ensuring the dimensional stability of the reinforcing phase in the high-temperature environment of deep wells. Finally, the gradient microstructure constructed in this invention achieves a strong interfacial bond dominated by chemical bonding between the reinforcing phase and the matrix. The carbides / carbonitrides generated at the interface act as rivet points, which not only efficiently transfer loads and improve material strength but also induce deflection and bridging during crack propagation, dissipating deformation energy. This significantly improves the high-temperature yield strength of the material while avoiding brittle fracture caused by interfacial debonding, achieving a synergistic improvement in strength, toughness, and high-temperature stability, and meeting the stringent requirements of drill pipe materials under complex deep well conditions. Detailed Implementation

[0026] To make the objectives, technical solutions, and advantages of this invention clearer, the invention will be further described in detail below with reference to specific embodiments.

[0027] The sources or properties of the raw materials used in the embodiments and comparative examples of this invention are as follows: monolayer graphene oxide powder: purchased from Nanjing Xianfeng Nanomaterials Technology Co., Ltd., model XF002-2, with a sheet diameter of 3μm and a thickness of 1nm; vanadium acetylacetonate: purchased from Shanghai Aladdin Biochemical Technology Co., Ltd., with a purity of 98%; dopamine hydrochloride: purchased from Shanghai Maclean Biochemical Technology Co., Ltd., with a purity of 99%; vanadium trichloride aqueous solution: 0.1mol / L.

[0028] Example 1: A method for preparing a high-strength pressure-resistant alloy material for drill pipes, the specific steps are as follows: (1) Weigh 400mg of single-layer graphene oxide powder and disperse it in 450mL of deionized water, and ultrasonically treat it for 50min at a power of 350W to form a uniform graphene oxide dispersion; take another 80mL of anhydrous ethanol, add 2.5g of acetylacetone vanadium to it, stir and dissolve it to form a uniform dispersion, and then slowly add it dropwise to the graphene oxide dispersion. Stir magnetically for 3h under a water bath at 35℃, and then transfer the mixture to a high-pressure reactor with a polytetrafluoroethylene liner. Add 8mL of ethylenediamine, seal it, and place it in a homogenizing furnace. Solventize at 170℃. The reaction was carried out for 10 hours. After the reaction was completed, the mixture was naturally cooled to room temperature. The black precipitate was collected by centrifugation and washed three times with anhydrous ethanol. The mixture was then dried in a vacuum drying oven at 60°C for 10 hours to obtain intercalated reduced graphene oxide composite powder. (2) 500 mL of 8 mM tris(hydroxymethyl)aminomethane buffer solution was prepared and the pH value was adjusted to 8.3 with hydrochloric acid. 400 mg of intercalated reduced graphene oxide composite powder was dispersed in the buffer solution and ultrasonically dispersed for 25 min to form a uniform suspension. 800 mg of dopamine hydrochloride was weighed and added to the suspension. The mixture was mechanically stirred at room temperature for 2.5 h. Then, 15 mL of vanadium trichloride aqueous solution was added to the reaction system and stirring was continued. 1.5h, after the reaction is completed, after centrifugation and washing with deionized water 3 times, it is vacuum dried at 55℃ for 20h to obtain modified composite precursor powder; (3) The matrix alloy powder is prepared by vacuum induction melting gas atomization method. The high-purity metal raw materials are weighed according to the following weight percentages: carbon (C) 0.28%, silicon (Si) 0.3%, manganese (Mn) 1.5%, phosphorus (P) 0.015%, sulfur (S) 0.010%, chromium (Cr) 1.2%, nickel (Ni) 0.035%, copper (Cu) 0.3%, vanadium (V) 0.1%, and the balance is iron (Fe). The above raw materials are placed in an alumina crucible and heated to 16 under argon protection. 00℃ to completely melt it and keep it at that temperature for 20 minutes to ensure uniform composition. Then, the melt is introduced into the atomizing nozzle and atomized using a high-purity nitrogen gas flow at a pressure of 4.5MPa. Spherical alloy powder with a particle size of 15-53μm is selected as the matrix alloy powder after screening. (4) The matrix alloy powder and the modified composite precursor powder are weighed according to a weight percentage of 99.0%:1.0% and placed together in a high-energy planetary ball mill. Under argon protection, they are mixed and ball-milled at a speed of 280r / min for 1.5h. The mixed powder is then loaded into a stainless steel tubular sleeve. During the filling process, a high-frequency mechanical vibration table (frequency 50Hz) is used. Then, the sleeve is evacuated to 1×10 -3The material is heated to 450℃, and after the sealing sleeve is clamped off, the sealing sleeve is placed in a hot isostatic press. Argon gas is used as the pressure transmission medium, and the temperature is increased to 800℃ at a rate of 10℃ / min. At the same time, the pressure is increased by gas filling and pressurization, so that the pressure reaches 80MPa simultaneously. The temperature is held for 30min, and then the temperature is increased to 1100℃ at a rate of 5℃ / min, while the pressure is increased to 120MPa. The temperature and pressure are held for 3h, and then the material is cooled to below 300℃ in the furnace to obtain the blank. Finally, the material is subjected to quenching and tempering heat treatment, heated to 900℃ and held for 50min for austenitization and water quenching, and then tempered at 580℃ for 1.5h. After air cooling, the high-strength pressure-resistant drill pipe alloy material is obtained.

[0029] Example 2: A method for preparing a high-strength pressure-resistant alloy material for drill pipes, the specific steps are as follows: (1) Weigh 500mg of single-layer graphene oxide powder and disperse it in 500mL of deionized water, and ultrasonically treat it for 60min at a power of 400W to form a uniform graphene oxide dispersion; take another 100mL of anhydrous ethanol, add 3g of acetylacetone vanadium to it, stir and dissolve it to form a uniform dispersion, and then slowly add it dropwise to the graphene oxide dispersion. Stir magnetically for 4h under a water bath at 40℃, and then transfer the mixture to a high-pressure reactor with a polytetrafluoroethylene liner. Add 10mL of ethylenediamine, seal it, and place it in a homogenizing furnace for dissolution at 180℃. The reaction was carried out for 12 hours. After the reaction was completed, the mixture was naturally cooled to room temperature. The black precipitate was collected by centrifugation and washed three times with anhydrous ethanol. The mixture was then dried in a vacuum drying oven at 60°C for 12 hours to obtain intercalated reduced graphene oxide composite powder. (2) 500 mL of 10 mM tris(hydroxymethyl)aminomethane buffer solution was prepared and the pH was adjusted to 8.5 with hydrochloric acid. 500 mg of intercalated reduced graphene oxide composite powder was dispersed in the buffer solution and ultrasonically dispersed for 30 min to form a uniform suspension. 1000 mg of dopamine hydrochloride was weighed and added to the suspension. The mixture was mechanically stirred at room temperature for 3 hours. Then, 20 mL of vanadium trichloride aqueous solution was added to the reaction system. Continue stirring for 2 hours. After the reaction is complete, centrifuge, wash with deionized water 3 times, and then vacuum dry at 60°C for 24 hours to obtain modified composite precursor powder; (3) Prepare matrix alloy powder by vacuum induction melting gas atomization method. Weigh the following high-purity metal raw materials according to the following weight percentages: carbon (C) 0.28%, silicon (Si) 0.3%, manganese (Mn) 1.5%, phosphorus (P) 0.018%, sulfur (S) 0.015%, chromium (Cr) 1.2%, nickel (Ni) 0.035%, copper (Cu) 0.3%, vanadium (V) 0.1%, with the remainder being iron (Fe). Place the above raw materials in an alumina crucible and heat to 1 under argon protection. The melt was completely melted at 600℃ and kept at that temperature for 20 minutes to ensure uniform composition. Then the melt was introduced into the atomizing nozzle and atomized using a high-purity nitrogen gas flow at a pressure of 4.5 MPa. Spherical alloy powder with a particle size of 15-53 μm was screened and used as the matrix alloy powder. (4) The matrix alloy powder and the modified composite precursor powder were weighed according to a weight percentage of 99.3%:0.7% and placed together in a high-energy planetary ball mill. The mixture was ball-milled at a speed of 300 r / min for 2 hours under argon protection. The mixed powder was then loaded into a stainless steel tubular sleeve. During the loading process, a high-frequency mechanical vibration table (frequency 55 Hz) was used. The sleeve was then evacuated to 1×10 -3The material is heated to 450℃, and after the sealing sleeve is clamped off, the sealing sleeve is placed in a hot isostatic press. Argon gas is used as the pressure transmission medium, and the temperature is increased to 830℃ at a rate of 13℃ / min. At the same time, the pressure is increased by gas filling and pressurization, so that the pressure reaches 80MPa simultaneously. The temperature is held for 45min, and then the temperature is increased to 1150℃ at a rate of 7℃ / min, while the pressure is increased to 120MPa. The temperature and pressure are held for 3h, and then the material is cooled to below 300℃ in the furnace to obtain the blank. Finally, the material is subjected to quenching and tempering heat treatment, heated to 920℃ and held for 60min for austenitization and water quenching, and then tempered at 600℃ for 2h. After air cooling, the high-strength pressure-resistant drill pipe alloy material is obtained.

[0030] Example 3: A method for preparing a high-strength pressure-resistant alloy material for drill pipes, the specific steps are as follows: (1) Weigh 600mg of single-layer graphene oxide powder and disperse it in 550mL of deionized water, and ultrasonically treat it for 70min at a power of 450W to form a uniform graphene oxide dispersion; take another 120mL of anhydrous ethanol, add 3.5g of acetylacetone vanadium to it, stir and dissolve to form a uniform dispersion, and then slowly add it dropwise to the graphene oxide dispersion. Stir magnetically for 5h under a water bath at 45℃, and then transfer the mixture to a high-pressure reactor with a polytetrafluoroethylene liner. Add 12mL of ethylenediamine, seal and place in a homogenizing furnace, and dissolve at 190℃. The reaction was carried out for 14 hours. After the reaction was completed, the mixture was naturally cooled to room temperature. The black precipitate was collected by centrifugation and washed three times with anhydrous ethanol. The mixture was then dried in a vacuum drying oven at 60°C for 14 hours to obtain intercalated reduced graphene oxide composite powder. (2) 500 mL of 12 mM tris(hydroxymethyl)aminomethane buffer solution was prepared and the pH was adjusted to 8.7 with hydrochloric acid. 600 mg of intercalated reduced graphene oxide composite powder was dispersed in the buffer solution and ultrasonically dispersed for 35 min to form a uniform suspension. 1200 mg of dopamine hydrochloride was weighed and added to the suspension. The mixture was mechanically stirred at room temperature for 3.5 h. Then, 25 mL of vanadium trichloride aqueous solution was added to the reaction system. Continue stirring for 2.5 h. After the reaction is complete, centrifuge, wash with deionized water 3 times, and then vacuum dry at 65°C for 28 h to obtain modified composite precursor powder; (3) Prepare matrix alloy powder by vacuum induction melting gas atomization method. Weigh the following high-purity metal raw materials according to the following weight percentages: carbon (C) 0.28%, silicon (Si) 0.3%, manganese (Mn) 1.5%, phosphorus (P) 0.020%, sulfur (S) 0.015%, chromium (Cr) 1.2%, nickel (Ni) 0.035%, copper (Cu) 0.3%, vanadium (V) 0.1%, with the remainder being iron (Fe). Place the above raw materials in an alumina crucible and heat to 1 under argon protection. The melt was completely melted at 600℃ and kept at that temperature for 20 minutes to ensure uniform composition. Then the melt was introduced into the atomizing nozzle and atomized using a high-purity nitrogen gas flow at a pressure of 4.5 MPa. Spherical alloy powder with a particle size of 15-53 μm was screened and used as the matrix alloy powder. (4) The matrix alloy powder and the modified composite precursor powder were weighed according to a weight percentage of 99.5%:0.5% and placed together in a high-energy planetary ball mill. The mixture was ball-milled at a speed of 320 r / min for 2.5 h under argon protection. The mixed powder was then loaded into a stainless steel tubular sleeve. During the loading process, a high-frequency mechanical vibration table (frequency 60 Hz) was used. The sleeve was then evacuated to 1×10 -3The material is heated to 450℃, and after the sealing sleeve is clamped off, the sealing sleeve is placed in a hot isostatic press. Argon gas is used as the pressure transmission medium, and the temperature is increased to 850℃ at a rate of 15℃ / min. At the same time, the pressure is increased by gas filling and pressurization, so that the pressure reaches 80MPa simultaneously. The temperature is held for 60min, and then the temperature is increased to 1200℃ at a rate of 8℃ / min, while the pressure is increased to 120MPa. The temperature and pressure are held for 3h, and then the material is cooled to below 300℃ in the furnace to obtain the blank. Finally, the material is subjected to quenching and tempering heat treatment, heated to 940℃ and held for 70min for austenitization and water quenching, and then tempered at 620℃ for 2.5h. After air cooling, the high-strength pressure-resistant drill pipe alloy material is obtained.

[0031] Comparative Example 1: The difference from Example 2 is that vanadium acetylacetone was not added in step (1), while the other conditions were the same as in Example 2.

[0032] Comparative Example 2: The difference from Example 2 is that vanadium trichloride aqueous solution was not added in step (2), while the other conditions were the same as in Example 2.

[0033] Comparative Example 3: The difference from Example 2 is that in step (4), the modified composite precursor powder is replaced with intercalated reduced graphene oxide composite powder, while the other conditions are the same as in Example 2.

[0034] Comparative Example 4: The difference from Example 2 is that no modified composite precursor powder is added in step (4), while the other conditions are the same as in Example 2.

[0035] Comparative Example 5: The difference from Example 2 is that in step (4), the modified composite precursor powder is replaced with an equal amount of monolayer graphene oxide powder, vanadium acetylacetonate and vanadium trichloride mixture, and the mass ratio of monolayer graphene oxide powder, vanadium acetylacetonate and vanadium trichloride is 500:3000:315. The other conditions are the same as in Example 2.

[0036] Performance Testing: Tensile property testing: Performed according to GB / T 228.1-2021 "Metallic materials, tensile testing—Part 1: Tests at room temperature". Standard tensile specimens were cut from the sintered green bodies prepared in the examples and comparative examples using an electric discharge wire cutter. The gauge length was 25 mm, and the diameter of the parallel sections was 5 mm. Testing was conducted using a universal testing machine equipped with an extensometer. The tensile rate was controlled at 1 mm / min. Five parallel specimens were tested for each group of samples, and the average value was recorded. Tensile strength (Rm), yield strength (Rp0.2), and elongation at break (A) were recorded. Room temperature impact toughness testing: Performed according to GB / T The test was conducted according to GB / T 229-2020 "Charpy Pendulum Impact Test Method for Metallic Materials". The sintered billet was machined into a standard V-notch specimen with dimensions of 10mm × 10mm × 55mm and a notch depth of 2mm. The test was performed using a pendulum impact tester at room temperature (23℃). The impact absorbed energy (KV2) of each specimen was recorded, and the average value of three specimens in each group was taken. Rockwell hardness testing was performed according to GB / T 230.1-2018 "Metallic Materials - Rockwell Hardness Test - Part 1: Test Method". A Rockwell hardness tester was used with a C scale (HRC). At least five different locations were selected on the polished surface of the specimen for point testing, with a point spacing greater than 3mm. The applied force was 150kgf, and the holding time was 10s. The arithmetic mean of the five measurements was taken as the final hardness value. High-temperature tensile property testing was performed according to GB / T The test was conducted according to 228.2-2015 "Metallic Materials, Tensile Testing Part 2: High Temperature Test Method". The specimen size was the same as that of the room temperature tensile specimen. The specimen was installed on a tensile testing machine with a high temperature environment chamber and heated to 180℃ (simulating the temperature of deep well operation) at a rate of 10℃ / min. The temperature was then maintained for 20min to ensure uniform specimen temperature. The test rate was controlled by strain rate, with a range of 0.00025 / s. After the test, the yield strength at 180℃ (Rp0.2, 180℃) was recorded. The yield strength attenuation rate was calculated according to the formula: Attenuation rate = [(Rp0.2 at room temperature - Rp0.2 at 180℃) / Rp0.2 at room temperature] × 100%. All test results are shown in Table 1.

[0037] Table 1 Performance Test Results

[0038] Data Analysis: As can be seen from the data in Examples 1-3 of Table 1, the high-strength, pressure-resistant drill pipe alloy material prepared by this invention successfully achieves excellent high-temperature stability and a good strength-toughness balance while ensuring extremely high strength. This indicates that the microstructure constructed by adjusting the raw material ratio in this invention has good process robustness. This is likely due to the effective functioning of the internal vanadium nitride hard core support and the external vanadium carbonitride quantum dot flexible pinning structure. This structure not only provides strong dispersion strengthening and fine-grain strengthening effects at room temperature, but more importantly, it effectively hinders grain boundary slip and dislocation climb at high temperatures. This overcomes the common problem of traditional nano-reinforced phases easily undergoing Ostwald ripening at high temperatures, leading to strengthening failure, and fully meets the stringent requirements for material mechanical properties in deep and ultra-deep well drilling operations.

[0039] As can be seen from the data in Table 1 for Example 2 and Comparative Example 1, the interlayer intercalation step of vanadium acetylacetonate plays a decisive role in maintaining the high-temperature strength stability of the material. It is speculated that this is because the in-situ generated interlayer nitride hard core of vanadium acetylacetonate is equivalent to driving wedges between the graphene sheets, effectively preventing interlayer collapse. This unique internal support structure provides a more rigid constraint to the matrix at high temperatures, thereby significantly reducing the thermal decay of the material.

[0040] As can be seen from the data in Example 2 and Comparative Example 2 in Table 1, the secondary chelation of vanadium ions by the polydopamine interface layer is a key technical feature for solving the problems of insufficient toughness and poor interfacial bonding in nano-reinforced materials. It is speculated that this is because the vanadium ions introduced through chelation transform into dispersed vanadium carbonitride quantum dots at high temperatures. These quantum dots form strong chemical bonds (pinning effect) between the matrix and the reinforcing phase, which can effectively transfer loads and improve strength, and also absorb energy through interfacial deflection cracks, thereby avoiding brittle fracture caused by interfacial debonding and achieving a synergistic improvement in strength and toughness.

[0041] As can be seen from the data in Example 2 and Comparative Example 3 in Table 1, the complete interlayer intercalation + surface chelation dual modification strategy is superior to a single modification method. This technique can construct a gradient transition layer through surface modification, and truly transform the excellent properties of the modified precursor into the mechanical properties of the macroscopic material.

[0042] As can be seen from the data in Example 2 and Comparative Example 4 in Table 1, the composite material of the present invention achieves a significant improvement in mechanical properties compared to the pure matrix alloy. This is presumably due to the construction of a heat-resistant reinforcing network at the matrix grain boundaries through a special microstructure design, which effectively suppresses high-temperature softening and demonstrates the advanced design of the metal matrix composite material.

[0043] As can be seen from the data in Table 1 for Example 2 and Comparative Example 5, the in-situ chemical modification route is significantly superior to the traditional physical mixing process. This indicates that molecular-level assembly and in-situ reaction achieved through chemical means ensure the uniform dispersion of the reinforcing phase and the metallurgical bonding of the interface, thereby achieving toughness and high-temperature stability far exceeding those of the physically mixed state while maintaining high strength.

[0044] Those skilled in the art should understand that the discussion of any of the above embodiments is merely exemplary and is not intended to imply that the scope of the invention is limited to these examples; within the framework of the invention, the technical features of the above embodiments or different embodiments can also be combined, the steps can be implemented in any order, and there are many other variations of the different aspects of the invention as described above, which are not provided in detail for the sake of brevity.

Claims

1. A high-strength, pressure-resistant alloy material for drill pipes, characterized in that, The high-strength pressure-resistant drill pipe alloy material is obtained by mixing, grinding, and sintering a matrix alloy powder and a modified composite precursor powder. The modified composite precursor powder is made from monolayer graphene oxide powder as raw material. After vanadium acetylacetonate intercalation and solvothermal reduction to form intercalated reduced graphene oxide composite powder, a polydopamine active layer is constructed on its surface in a tris(hydroxymethyl)aminomethane buffer using the self-oxidative polymerization reaction of dopamine hydrochloride. The polydopamine active layer is formed through the coordination chelation effect of this layer on vanadium trichloride.

2. The high-strength pressure-resistant drill pipe alloy material according to claim 1, characterized in that, The weight percentage of the matrix alloy powder and the modified composite precursor powder is 99.0%-99.5%: 0.5%-1.0%.

3. The high-strength pressure-resistant drill pipe alloy material according to claim 1, characterized in that, The matrix alloy powder is prepared by vacuum induction melting gas atomization method, and the weight percentage of each element is as follows: carbon (C) 0.28%, silicon (Si) 0.3%, manganese (Mn) 1.5%, phosphorus (P) <0.025%, sulfur (S) <0.025%, chromium (Cr) 1.2%, nickel (Ni) 0.035%, copper (Cu) 0.3%, vanadium (V) 0.1%, and the balance is iron (Fe).

4. The high-strength pressure-resistant drill pipe alloy material according to claim 1, characterized in that, The ratio of the monolayer graphene oxide powder, vanadium acetylacetonate, and ethylenediamine is 400-600 mg: 2.5-3.5 g: 8-12 mL.

5. The high-strength pressure-resistant drill pipe alloy material according to claim 1, characterized in that, The ratio of the intercalated reduced graphene oxide composite powder, dopamine hydrochloride, and vanadium trichloride aqueous solution is 400-600mg:800-1200mg:15-25mL.

6. The high-strength pressure-resistant drill pipe alloy material according to claim 1, characterized in that, The solvothermal reduction reaction temperature is 170-190℃, and the reaction time is 10-14h.

7. A method for preparing a high-strength, pressure-resistant drill pipe alloy material according to any one of claims 1-6, characterized in that, The process includes the following steps: mixing and grinding the matrix alloy powder and the modified composite precursor powder evenly, then loading them into a mold for hot isostatic pressing, and finally subjecting them to quenching and tempering heat treatment after cooling to obtain a high-strength, pressure-resistant drill pipe alloy material.

8. The method for preparing the high-strength pressure-resistant drill pipe alloy material according to claim 7, characterized in that, The grinding was carried out under argon protection, with a rotation speed of 280-320 r / min and a ball milling time of 1.5-2.5 h.

9. The method for preparing the high-strength pressure-resistant drill pipe alloy material according to claim 7, characterized in that, The filling process of the mold is carried out in conjunction with a high-frequency mechanical vibration table (frequency 50-60Hz); the hot isostatic pressing uses argon as the pressure transmission medium, first heating to 800-850℃ at a rate of 10-15℃ / min, maintaining a pressure of 80MPa, holding for 30-60min, and then continuing to heat to 1100-1200℃ at a rate of 5-8℃ / min, maintaining a pressure of 120MPa, and holding for 3h.

10. The method for preparing the high-strength pressure-resistant drill pipe alloy material according to claim 7, characterized in that, The heat treatment involves austenitizing water quenching at 900-940℃ for 50-70 minutes, followed by high-temperature tempering at 580-620℃ for 1.5-2.5 hours.

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