Nickel-based alloy oil casing for laser-electric arc composite additive manufacturing of threads and method

Abstract

The invention discloses a nickel-based alloy oil casing for laser-electric arc composite additive manufacturing of threads and a method, and belongs to the technical field of manufacturing of underground equipment for oil and gas field exploitation. According to the method, through the laser-arc time sequence composite additive manufacturing process, the threads are directly manufactured at the end of the nickel-based alloy oil casing in an additive mode, the threads are directly manufactured on the outer surface of the end opening part of the nickel-based alloy oil casing, the threads are made of nickel-based alloy of the same type as a base material, the metallurgical bonding performance of the threads and the base is enhanced, and the service life of the nickel-based alloy oil casing is prolonged. The cladding speed is increased while the thread bonding strength is guaranteed, the additive manufacturing efficiency and the additive thread strength are improved through the laser arc composite technology, and the problem that the thread laser additive strength is low is solved. According to the method, the mechanical performance of the additive remanufactured thread can be effectively improved, the stress structure of the thread part is improved, the service life of the thread is prolonged, and the production and manufacturing cost of the nickel-based alloy oil pipe is greatly reduced.

Description

Technical Field

[0001] This invention belongs to the field of downhole equipment manufacturing technology for oil and gas field development, and relates to a method for manufacturing threads in nickel-based alloy oil casing using laser-arc composite additive manufacturing. Background Technology

[0002] Laser cladding technology, as a key technology in laser additive manufacturing, has broad application prospects. It is mainly used to prepare coatings with high hardness, wear resistance, and corrosion resistance, and can replace chrome plating and arc welding techniques for preparing special functional coatings on the surface of parts. It is suitable for the manufacturing and remanufacturing of high-end products.

[0003] For oil casing used in conditions involving high sulfur content, high temperature, and high pressure, nickel-based alloy oil casing is typically used. When nickel-based alloy oil casing is pulled out during well workovers, it generally only suffers from slight corrosion, with an extremely low annual corrosion rate that does not affect its continued use. It can be run back into the well for reuse with almost no treatment. The only drawback is that damage to the threads during the running-in / run-out process can easily lead to failure. This localized damage affects the overall service life of the product. Currently, there are no effective repair methods for the threads of nickel-based alloy oil casing in oil and gas fields. The procurement cost of nickel-based alloy oil casing is high, and the failure of nickel-based alloy tubing due to thread damage causes significant economic losses to oil and gas fields every year.

[0004] Typically, laser cladding is used for the remanufacturing repair of parts (such as threads) by dimensional repair and preparation of functional coatings. It has the advantages of low dilution rate, metallurgical bonding between coating and substrate, and high strength, hardness and corrosion resistance of coating. It can meet the remanufacturing repair of parts under most working conditions. However, the microstructure of the laser cladding layer material is that of cast titanium. The comprehensive mechanical properties of the thread surface cladding layer manufactured by laser cladding often cannot reach the level of castings or forgings. Summary of the Invention

[0005] The purpose of this invention is to overcome the shortcomings of the prior art and provide a method for manufacturing threads in nickel-based alloy oil sleeves using laser-arc composite additive manufacturing. This addresses the problems in the prior art where nickel-based alloy oil sleeves are easily scrapped due to damage to the threaded screws, and where the comprehensive mechanical properties of the thread surface cladding layer manufactured solely through laser cladding are difficult to achieve the level of castings or forgings.

[0006] To achieve the above objectives, the present invention employs the following technical solution: A method for laser-arc composite additive manufacturing of threads on nickel-based alloy oil casing includes the following steps: S1, turning nickel-based alloy oil pipe to remove the threads at the end, leaving the outer surface of the end smooth and flat; S2, threads are manufactured on the outer surface of the port part by laser cladding-arc additive composite additive method. Both the laser cladding powder and the arc additive wire are made of nickel-based alloy, and nano-reinforcing particles are added to the powder. S3, after each cladding layer is clad, the cladding layer is subjected to ultrasonic rolling treatment; S4, repeat S2 and S3 until the thread additive manufacturing is completed; S5, machining the threads of the threaded pipe opening to achieve the required dimensional accuracy and surface roughness of the threads; S6, nickel-based alloy oil casing is produced by laser impact strengthening treatment of the thread root.

[0007] A further improvement of the present invention is that: Preferably, in S1, the turning dimension is the maximum height of the thread minus 0.5 mm.

[0008] Preferably, in S2, the laser cladding powder is a mixture of nickel-based alloy powder, TiB2, and nano-rare earth reinforcing particles; the material for the arc additive manufacturing is nickel-based alloy wire.

[0009] Preferably, in S2, each cladding layer is clad using a laser-arc synchronous composite additive cladding process. When starting, the laser is turned on first, followed by the arc. The timing interval between the laser and the arc is 50-100ms. After the molten pool is formed, the laser and the arc act synchronously on the molten pool, and the cladding layer is formed by trajectory movement.

[0010] Preferably, in S2, the start-up time interval between laser cladding and arc additive manufacturing is 50-100ms. After start-up, the laser and arc work synchronously to form a molten pool. The scanning speed is 30-50mm / s, the overlap rate is 40%-60%, and the protective gas flow rate is 10-20L / min.

[0011] Preferably, during the cladding process, the laser power is 2.8-3.2kW, the spot diameter is φ3.0-5.0mm, and the powder feeding speed is 2-5g / min.

[0012] Preferably, during the cladding process, the arc current is 250-300A and the wire feeding speed is 20-50g / min.

[0013] Preferably, in S3, during the rolling process, the amplitude is 30μm, the frequency is 20kHz, the moving linear speed is 10mm / s, and the inter-pass overlap rate is 50%.

[0014] Preferably, in S7, during the laser shock strengthening process, the power density is 10. 10 W / cm 2 The shock wave pressure was 4.5 GPa, and a water film confinement layer was used.

[0015] A nickel-based alloy oil casing prepared by any of the above methods, wherein the threaded portion of the nickel-based alloy oil casing has a tensile strength ≥850 MPa and a shear strength ≥700 MPa.

[0016] Compared with the prior art, the present invention has the following beneficial effects: This invention discloses a method for remanufacturing threads on nickel-based alloy oil casing using laser-arc composite additive manufacturing. This method is applicable to the repair and performance enhancement of old oil casing in highly corrosive oil and gas wells containing H2S and CO2. The method uses laser-arc composite cladding manufacturing technology to remanufacture damaged threads, including the design of functional composite materials, laser-arc composite additive manufacturing process, and post-processing methods for thread additive manufacturing. It can effectively improve the mechanical properties of additively manufactured threads, improve the stress structure of the threaded parts, increase the service life of the threads, and greatly reduce the production cost of nickel-based alloy oil tubing. The nickel-based alloy oil casing thread of this invention, after remanufacturing, possesses the excellent corrosion resistance of nickel-based alloys. Because the thread is directly fabricated on the outer surface of the nickel-based alloy oil casing port portion, and the thread uses the same type of nickel-based alloy as the base material, with the addition of a certain proportion of reinforcing material, the metallurgical bond between the thread and the base material is enhanced. This ensures the thread bonding strength while increasing the cladding rate. Furthermore, the use of laser-arc composite technology greatly improves the efficiency of additive manufacturing and the strength of the additive thread, reduces the impact on the mechanical properties of the oil casing base material, and solves the problem of low strength in laser-added threads.

[0017] Furthermore, by synchronously controlling the laser and the electric arc, the high performance of electric arc additive manufacturing is achieved while the introduction of the laser greatly increases the cladding speed, reduces the heat input of pure electric arc additive manufacturing, and reduces the impact of cladding additive manufacturing on the substrate performance.

[0018] Furthermore, the post-processing uses ultrasonic rolling to strengthen the surface of the cladding layer, improving its microstructure and properties. Laser shock peening is used to strengthen the root of the thread after machining, changing the residual stress state at the thread root and improving the thread's fatigue resistance.

[0019] The second aspect of the present invention discloses a nickel-based alloy oil sleeve with a laser-arc composite additive manufacturing thread. The sleeve thread uses a functional composite material, and the final thread threading count can be increased from ≤4 times to more than 5 times without damage. Attached Figure Description

[0020] Figure 1 This is a flowchart of the present invention; Figure 2 This is a schematic diagram of the structure of a nickel-based alloy oil casing. Detailed Implementation

[0021] The present invention will now be described in further detail with reference to the accompanying drawings: To enable those skilled in the art to understand the features and effects of the present invention, the terms and expressions used in the specification and claims are explained and defined in general below. Unless otherwise specified, all technical and scientific terms used herein have the ordinary meaning understood by those skilled in the art regarding the present invention, and in case of conflict, the definitions in this specification shall prevail.

[0022] In this article, unless otherwise specified, “contains,” “includes,” “containing,” “has,” or similar terms cover the meanings of “composed of” and “mainly composed of,” for example, “A contains a” covers the meanings of “A contains a and others” and “A contains only a.”

[0023] The present invention will be further illustrated below with reference to specific embodiments. It should be understood that these embodiments are for illustrative purposes only and are not intended to limit the scope of the invention. Furthermore, it should be understood that after reading the teachings of this invention, those skilled in the art can make various alterations or modifications to the invention, and these equivalent forms also fall within the scope defined by the appended claims.

[0024] The following examples use instruments and equipment conventional in the art. Experimental methods in the following examples, unless otherwise specified, are generally performed under conventional conditions or as recommended by the manufacturer. All raw materials used in the following examples are conventional commercially available products with specifications conventional in the art. In this specification and the following examples, unless otherwise specified, "%" refers to weight percentage, "parts" refers to parts by weight, and "ratio" refers to weight proportion.

[0025] In existing technologies, laser cladding technology is widely used for surface repair of parts and preparation of functional coatings, but it has significant limitations in the field of repairing nickel-based alloy oil casing threads. Traditional laser cladding layers have cast-state structural defects, and their comprehensive mechanical properties are difficult to reach the level of forgings, failing to meet the combined strength and toughness requirements of threaded connections. Especially in the high-sulfur, high-temperature, and high-pressure conditions of oil and gas fields, local damage to nickel-based alloy oil casing threads caused by well tripping operations often leads to complete scrapping. Existing repair methods cannot achieve simultaneous improvement in metallurgical bonding and mechanical properties, resulting in significant economic losses.

[0026] To address the aforementioned issues, such as stress concentration at the thread root leading to fatigue cracking, insufficient repair layer density, and low interfacial bonding strength, this invention prioritizes the synergistic effect of laser cladding and arc additive manufacturing to directly fabricate threads on the casing substrate.

[0027] See Figure 1The first aspect of this invention discloses a method for manufacturing threads on nickel-based alloy oil casing using laser-arc composite additive manufacturing, the method comprising the following steps: S1, turning nickel-based alloy oil pipe to remove the threads at the end, leaving the outer surface of the end smooth and flat; S2, threads are manufactured on the outer surface of the port portion by laser cladding-arc additive composite additive method, and the laser cladding powder and the arc additive wire are made of the same type of nickel-based alloy material; S3, after each cladding layer is clad, the cladding layer is rolled. S4, repeat S2 and S3 until the thread cladding layer manufacturing is completed; S5 uses a CNC lathe to process the cladding layer at the pipe opening to meet the dimensional and precision requirements of the thread; S6, nickel-based alloy oil casing is produced by laser impact strengthening treatment of the thread root.

[0028] Turning refers to forming a reference machining surface through mechanical cutting, which can be achieved using a CNC lathe, providing a geometric positioning reference for subsequent additive manufacturing. Laser cladding-arc additive composite manufacturing refers to a collaborative manufacturing process that simultaneously uses high-energy laser cladding and arc deposition, specifically achieved using a coaxial powder-feeding laser head and an arc welding torch combination. The laser cladding is a coaxial powder-feeding DED process, balancing cladding layer density and forming efficiency. Furthermore, the laser simultaneously acts on the arc molten pool, with the laser and arc working synergistically to form a laser-arc composite additive cladding layer. Rolling treatment refers to a post-processing method that improves material density through mechanical pressure, specifically achieved using an ultrasonic-assisted rolling device, eliminating interlayer porosity and refining grains. A ring-shaped cladding layer refers to a continuous reinforcing structure surrounding the threaded ends, specifically achieved using a circumferential scanning path, enhancing the deformation resistance of the threaded connection. Laser shock stabilization refers to surface modification using high-energy pulses to induce residual compressive stress, specifically achieved using a nanosecond-level pulsed laser, improving the fatigue resistance of the thread root.

[0029] This method achieves complementary advantages through composite additive manufacturing. The laser preheats the molten pool for the cladding layer and provides reinforcing phase materials via powder feeding, ensuring controllable composition of the cladding layer material. The electric arc layer, using wire material to improve manufacturing efficiency, is fed in, and the synergistic effect of the electric arc and laser achieves efficient and high-quality forming of the cladding layer. Traditional repair techniques lack interlayer treatment, leading to defect accumulation. This solution introduces an ultrasonic rolling process to significantly improve interlayer bonding quality. Compared to conventional heat treatment strengthening, laser shock strengthening offers localized precision and no heat-affected zone, making it more suitable for stress control at the thread root.

[0030] The method of this invention is applicable to nickel-based alloy corrosion-resistant oil casings of steel grades such as P110 / P125.

[0031] In some embodiments of the present invention, the turning dimension is the maximum height of the thread minus 0.5 mm, and the thickness of the thread additive layer is greater than the actual maximum height of the thread, ensuring that the threaded part after machining is entirely made of nickel-based alloy manufactured by DED additive manufacturing.

[0032] See Figure 2 Turning dimension refers to the radial cutting amount of material removed from the substrate surface through machining. This can be achieved by controlling the radial feed rate of a CNC lathe. This parameter is used to precisely control the depth of defect removal from the substrate surface. The maximum thread height -0.5mm refers to the cutting reference value determined based on the thread profile geometry parameters. This can be calculated after measuring the original thread profile using 3D scanning. This deviation is used to balance the matching relationship between the amount of substrate removed and the thickness of the additive manufacturing layer. During turning, by setting the cutting depth to a negative deviation of the theoretical thread height, insufficient cutting makes it difficult to ensure that subsequent threads are additively manufactured, reducing the thread's mechanical strength and the connection between the thread and the substrate. Excessive cutting reduces the effective load-bearing cross-section of the substrate, affecting the mechanical properties of the composite structure. By precisely controlling the cutting amount to be the theoretical height minus a fixed deviation value, both the damaged layer on the substrate surface is eliminated, and a uniform substrate surface morphology is provided for subsequent additive manufacturing processes. This solution establishes a quantitative cutting model based on thread geometry parameters, which achieves precise matching between the amount of substrate removed and the thickness of the additive layer, ensuring the accuracy of the restored thread dimensions and avoiding poor interface bonding caused by inaccurate dimensional control during the repair process.

[0033] In some embodiments of the present invention, the laser cladding powder is a mixture of nickel-based alloy, TiB2 and nano-rare earth reinforcing agent, and the arc additive manufacturing uses nickel-based alloy wire.

[0034] Nickel-based alloys refer to alloy materials of the same type as the oil casing substrate, specifically made using Inconel series alloys, to ensure metallurgical compatibility between the cladding layer and the substrate. TiB2 refers to titanium boride ceramic particles as a hard reinforcing phase, specifically made in powder form with a particle size of 5-15μm, used to suppress element diffusion, refine the grain size of the cladding layer, and improve hardness and wear resistance. Nano-rare earth reinforcing agents refer to nanoscale additives containing yttrium oxide or lanthanum oxide, specifically made in powder form with a particle size of 50-100nm, used to suppress grain boundary segregation and cracks, reduce porosity defects, refine grain size, and improve high-temperature oxidation resistance. Nickel-based alloys for arc additive manufacturing refer to metal wires of the same type as those used in laser cladding powder, used to ensure the compositional continuity between the additive layer and the cladding layer. In this embodiment, nano-ceramic reinforcing phase and rare earth reinforcing agent are added, reducing the brittle phase at the interface to less than 0.05%, resulting in excellent corrosion resistance and mechanical properties. The interfacial shear strength of the composite layer reaches more than 700 MPa, which is 60% higher than that of the traditional process.

[0035] During laser cladding, a nickel-based alloy forms a metallurgical bonding layer compatible with the casing substrate, while TiB2 particles are uniformly distributed in the molten pool to form a dispersed reinforcing phase. Nano-rare earth elements are adsorbed at grain boundaries to suppress impurity element segregation. In the subsequent arc additive manufacturing process, nickel-based alloy wire forms a deposition layer with the same composition as the cladding layer through droplet transfer. The synergistic effect of both processes gives the composite layer the advantages of fine-grained strengthening and rapid forming. This combination overcomes the limitations of traditional single laser cladding in forming coarse as-cast structures.

[0036] In some specific implementation schemes, for nickel-based alloy corrosion-resistant oil casings with P110 / P125 or similar steel grades as the base material, the final cladding layer composition includes 98.5 wt% Inconel 718, 1.0 wt% TiB2, and 0.5 wt% nano-rare earth reinforcing agent. The arc additive manufacturing process uses Inconel 718 wire, accounting for 90% of the wire feed mass; the laser cladding powder consists of 85 wt% Inconel 718 powder, 10 wt% TiB2, and 5 wt% nano-rare earth reinforcing agent, accounting for 10% of the powder feed mass. The wire-to-composite powder feed mass ratio is 9:1, with a commonly used wire feed rate of 20-50 g / min and a powder feed rate of 2-5 g / min. The specifications of Inconel 718 filament are φ1.2mm, Inconel 718 powder particle size is 38-75μm, and TiB2 particle size is 50-80nm; the filament feeding rate is 20-50g / min, and the powder feeding rate is 2-5g / min.

[0037] In some embodiments of the present invention, during each cladding layer, the laser is first activated, followed by the electric arc. The laser and electric arc processes are synchronized during the cladding process to complete the additive manufacturing. The pre-laser feeds powder to clad the composite powder material, forming a composite cladding layer molten pool at the interface layer and preheating the substrate. The subsequent electric arc additive cladding continuously feeds nickel-based alloy 718 wire into the molten pool, forming an integral nickel-based alloy composite cladding layer. The threaded laser-arc composite additive cladding layer in this invention is achieved through multi-layer cladding. During single-layer thread repair, a high-energy-density beam first forms a molten pool with metallurgical bonding characteristics on the substrate surface. Subsequently, the electric arc additive process is activated, forming a laser-arc composite cladding layer on the part surface. At this time, the laser and electric arc heat sources act simultaneously to generate a new molten pool, forming a laser-arc composite deposition layer on the workpiece surface. After completing one cladding layer, thicker cladding layers are accumulated, ultimately forming an integral cladding layer taller than the thread thread size. During this process, the laser-arc heat input causes partial remelting of the columnar crystal structure of the previous cladding layer, forming a fine equiaxed crystal transition zone. Simultaneously, the high cooling rate within the deposited layer results in a uniform grain distribution. The combined effect of these two processes leads to a refined microstructure in the composite additive layer, thereby enhancing the strength and deformation resistance of the thread repair area. In this implementation scheme, by limiting the process parameters of laser and arc and the material feed ratio, the advantages of the fine-grained structure of laser cladding are preserved, while the thermal cycling effect of the arc process optimizes the interlayer microstructure, and simultaneously allows for in-situ control of the cladding layer's composition.

[0038] In some embodiments of the present invention, the laser cladding parameters include a laser wavelength of 1064 nm, a power of 2.8-3.2 kW, a spot diameter of φ3.0-5.0 mm, and a powder feeding speed of 2-5 g / min. The arc additive manufacturing parameters use pulsed MIG with a current of 250-300 A and a wire feeding speed of 20-50 g / min.

[0039] In some embodiments of this invention, the distance between the laser spot position and the arc position in laser cladding and arc additive manufacturing is 2-3 mm, ensuring that the arc wire feeding position is within the laser spot, ultimately forming a laser-arc composite molten pool. The laser cladding equipment and the arc additive manufacturing equipment do not interfere with each other. The initial start-up time interval between the laser and the arc is 50-100 ms, the overall scanning speed is 30-50 mm / s, the overlap rate is 40%-60%, and the protective gas flow rate is 10-20 L / min. After the laser cladding process is completed, the arc additive manufacturing process starts within 50-100 ms. At this time, the cladding layer surface is in a semi-solidified state, and the arc heat source can achieve metallurgical bonding without damaging the integrity of the cladding layer. The combined effect of laser and arc can greatly improve the scanning speed of the cladding process. When the scanning speed is maintained at 30-50 mm / s, the molten pool maintains continuous and stable wetting and spreading, avoiding incomplete fusion defects caused by excessive speed. In contrast, the scanning speed of arc additive manufacturing alone is generally around 10 mm / s. When adjacent melt channels overlap by 40%-60% of their width, the subsequent melt pool can fully fuse the edge area of ​​the previous channel, while avoiding the coarsening of the microstructure caused by multiple remeltings. A shielding gas flow rate of 10-20 L / min covers the processing area, effectively removing atmospheric oxygen without causing surface fluctuations in the melt pool due to airflow impact. This invention, through laser-arc composite additive remanufacturing technology, achieves an additive deposition rate 200% higher than traditional laser cladding and arc additive manufacturing alone.

[0040] In some embodiments of the present invention, the cladding layer is rolled after each cladding layer is deposited. During the rolling process, the amplitude is 30 μm, the frequency is 20 kHz, the linear velocity is 10 mm / s, and the inter-pass overlap is 50%. In the laser-arc composite additive manufacturing process, rolling is performed immediately after each cladding layer is deposited. When the mechanical vibration with an amplitude of 30 μm acts on the surface of the cladding layer, it generates a dynamic plastic deformation effect, causing the coarse columnar crystal structure to transform into a fine equiaxed crystal structure. The high-frequency vibration with a frequency of 20 kHz effectively eliminates interlayer thermal stress and improves material density through stress wave propagation. The linear velocity is matched with the scanning speed of the cladding process, ensuring processing efficiency while avoiding local stress concentration. The 50% inter-pass overlap design of the rolling trajectory ensures that adjacent rolling passes have a 50% width overlap, ensuring that the entire cladding layer surface undergoes two rolling processes, thereby achieving uniform and dense microstructure. Each cladding layer is surface-treated by ultrasonic rolling to reduce the porosity of the cladding layer and improve its microstructure and stress state.

[0041] In some embodiments of the present invention, a power density of 10 is used in the laser shock peening process. 10 W / cm 2The laser beam generates a shock wave pressure on the order of 4.5 GPa, and a water film confinement layer is applied for surface treatment. During the laser shock treatment stage, the high-energy laser pulse is absorbed by the water film, forming a plasma explosion that generates a shock wave propagating into the material. The shock wave pressure induces a distributed residual compressive stress field in the thread root region, improving the material's resistance to crack propagation through grain refinement and dislocation multiplication mechanisms. The water film confinement layer simultaneously plays a dual role in controlling the shock wave propagation direction and providing cooling protection, preventing surface thermal damage. The process parameter combination is optimized for the stacking fault energy characteristics of nickel-based alloys, ensuring that the strengthening layer depth matches the stress concentration region at the thread root. Laser shock strengthening at the thread root significantly improves the stress state of the thread, increasing the number of threads from ≤4 to over 5, and improving the lifespan by 125%.

[0042] In some specific implementations, the thickness of the water film constraint layer can be controlled within the range of 0.1-0.3 mm, for example, by using a multi-hole nozzle to form a uniform water film. The laser impact path can be planned along the thread profile to ensure full coverage of the root region. The surface roughness after impact treatment can be controlled by adjusting the laser scanning overlap rate.

[0043] A nickel-based alloy oil casing with threads manufactured by laser-arc composite additive manufacturing has a threaded portion with a tensile strength of 850 MPa or more and a shear strength of 700 MPa or more.

[0044] The nickel-based alloy oil casing disclosed in this invention has a threaded portion tensile strength of 850 MPa or higher. While meeting the strength requirements of the oil casing thread, the tensile strength of the cladding layer is increased by more than 50% compared to traditional laser cladding processes. This nickel-based alloy oil casing meets the requirements for use in harsh operating environments.

[0045] The following description, in conjunction with specific embodiments, provides further details.

[0046] Example 1: Remanufacturing of φ88.9×6.45, P110 grade nickel-based alloy oil pipe threads.

[0047] The remanufacturing of P110 grade nickel-based alloy oil pipe threads was performed using laser-arc composite additive manufacturing technology. The process steps included: Step 1, Damaged thread turning For machining nickel-based alloy oil pipe threads (male threads), the entire thread is machined away. The machining dimension is the maximum thread height minus 0.5mm, and the machining depth on one side is 1.5-2.0mm. Ensure that the root of the thread is completely machined cleanly, and the machining length is 150mm.

[0048] Step 2, PT inspection of the cladding area surface Before cladding, the machined surfaces of the threaded areas are cleaned and subjected to penetrant testing to ensure that the cladding surface is free of defects such as cracks and porosity. The surface is then laser-cleaned again before cladding to remove stains and impurities.

[0049] Step 3, additive cladding of the tubing thread section The outer diameter of the threaded part is clad with laser-arc composite additive manufacturing equipment to perform laser-arc composite cladding on the threaded part of the outer surface of the oil pipe. The cladding thickness is 3mm on one side and 4.0mm within 20mm of the threaded end to ensure the processing of the shrinkage sealing surface size.

[0050] Cladding materials: Arc additive manufacturing uses Inconel 718 wire (φ1.2mm), accounting for 90% of the wire feed weight; Laser cladding powder consists of 85wt% Inconel 718 powder (particle size 38-75μm) + 10wt% TiB2 (particle size 50-80nm) + 5wt% nano rare earth reinforcing agent, accounting for 10% of the powder feed weight.

[0051] Composite cladding process parameters: laser power 3000W, spot diameter 4mm, powder feeding rate 5g / min; arc parameters: current 300A, wire feeding speed 50g / min; laser-arc distance 3mm, start-up timing interval 100ms, scanning speed 50mm / s, overlap 2.0mm, protective gas flow rate 10-20L / min. Single-layer cladding thickness 1.2mm, interlayer cooling using internal wall liquid nitrogen spray cooling below 50℃. Overall cladding layer thickness 2.5-3.0mm per side.

[0052] Step 4, ultrasonic rolling treatment of the cladding layer After each cladding layer is clad, the surface of the cladding layer is subjected to ultrasonic rolling treatment with an amplitude of 30μm and a frequency of 20kHz.

[0053] Step 5: Turning the pipe threads and seals. The pipe cladding layer is machined to the dimensions shown in the drawing using a CNC lathe for machining the threads and sealing parts.

[0054] Step 6, Thread post-processing After thread machining, laser shock peening is used to strengthen the root of the thread. Laser power density: 10 10 W / cm 2 The shock wave pressure was 4.5 GPa, the overlap rate was 30%, a water film constraint layer was used, and the shock wave was repeated 3 times.

[0055] Step 7, Thread accuracy and seal inspection The final machined threads and seals are inspected for dimensional accuracy and sealing performance.

[0056] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the protection scope of the present invention.

Claims

1. A method for manufacturing threads on nickel-based alloy oil casing using laser-arc composite additive manufacturing, characterized in that, Includes the following steps: S1, turning nickel-based alloy oil pipe to remove the threads at the end, leaving the outer surface of the end smooth and flat; S2, threads are manufactured on the outer surface of the port part by laser cladding-arc additive composite additive method. Both the laser cladding powder and the arc additive wire are made of nickel-based alloy, and nano-reinforcing particles are added to the powder. S3, after each cladding layer is clad, the cladding layer is subjected to ultrasonic rolling treatment; S4, repeat S2 and S3 until the thread additive manufacturing is completed; S5, machining the threads of the threaded pipe opening to achieve the required dimensional accuracy and surface roughness of the threads; S6, nickel-based alloy oil casing is produced by laser impact strengthening treatment of the thread root.

2. The method for manufacturing threads on a nickel-based alloy oil casing using laser-arc composite additive manufacturing according to claim 1, characterized in that, In S1, the turning dimension is the maximum height of the thread minus 0.5 mm.

3. The method for manufacturing threads on a nickel-based alloy oil casing using laser-arc composite additive manufacturing according to claim 1, characterized in that, In S2, the laser cladding powder is a mixture of nickel-based alloy powder, TiB2, and nano-rare earth reinforcing particles; the material for arc additive manufacturing is nickel-based alloy wire.

4. The method for manufacturing threads on a nickel-based alloy oil casing using laser-arc composite additive manufacturing according to claim 1, characterized in that, In S2, each cladding layer is clad using a laser-arc synchronous composite additive cladding process. When starting, the laser is turned on first, followed by the arc. The timing interval between the laser and the arc is 50-100ms. After the molten pool is formed, the laser and the arc act synchronously on the molten pool, and the cladding layer is formed by trajectory movement.

5. The method for manufacturing threads on a nickel-based alloy oil casing using laser-arc composite additive manufacturing according to claim 4, characterized in that, In S2, the start-up time interval between laser cladding and arc additive manufacturing is 50-100ms. After start-up, the laser and arc work synchronously to form a molten pool. The scanning speed is 30-50mm / s, the overlap rate is 40%-60%, and the protective gas flow rate is 10-20L / min.

6. The method for manufacturing threads on a nickel-based alloy oil casing using laser-arc composite additive manufacturing according to claim 1, characterized in that, During the cladding process, the laser power is 2.8-3.2kW, the spot diameter is φ3.0-5.0mm, and the powder feeding speed is 2-5g / min.

7. The method for manufacturing threads on a nickel-based alloy oil casing using laser-arc composite additive manufacturing according to claim 1, characterized in that, During the cladding process, the arc current is 250-300A and the wire feeding speed is 20-50g / min.

8. The method for manufacturing threads on a nickel-based alloy oil casing using laser-arc composite additive manufacturing according to claim 1, characterized in that, In S3, during the rolling process, the amplitude is 30μm, the frequency is 20kHz, the moving linear speed is 10mm / s, and the inter-pass overlap rate is 50%.

9. The method for manufacturing threads on a nickel-based alloy oil casing using laser-arc composite additive manufacturing according to claim 1, characterized in that, In S7, during laser shock peening, the power density is 10. 10 W / cm 2 The shock wave pressure was 4.5 GPa, and a water film confinement layer was used.

10. A nickel-based alloy oil casing prepared by any one of claims 1-9, characterized in that, The threaded portion of the nickel-based alloy oil casing has a tensile strength ≥850 MPa and a shear strength ≥700 MPa.

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