A laser cladding method for anticorrosion treatment of gas-tight sleeve threads

Abstract

This application belongs to the field of laser cladding, and specifically relates to a laser cladding method for corrosion protection of gas-tight sleeve threads. The method ensures accurate thread dimensions and improves sealing performance through pre-machining steps and subsequent rough and finish machining. The laser cladding process is used to prepare a laser cladding layer that enhances corrosion resistance. Based on the improved corrosion resistance using a 625 nickel-based alloy, graphite is added to the cladding layer. The use of nickel-coated graphite avoids oxidation and denaturation of the graphite during the cladding process. After machining, some graphite is exposed on the cross-section. Subsequent annealing in a carbon-containing atmosphere allows further graphite growth on the exposed surface, resulting in a slight protrusion of graphite compared to the machined surface. Therefore, after thread connection, a "micro-maze" structure composed of graphite protrusions is formed on the connection contact surface, further improving sealing performance.

Description

Technical Field

[0001] This invention belongs to the field of laser cladding, and specifically relates to a laser cladding method for corrosion protection of airtight sleeve threads. Background Technology

[0002] With the continuous growth of current energy demand and the ongoing promotion of renewable energy, energy storage technology has become an important way to resolve energy fluctuations and balance the contradiction between energy supply and demand. Air-based energy storage power generation technology, due to its advantages such as high efficiency, environmental friendliness, and flexibility, is increasingly becoming one of the key technologies in the energy storage industry. The core concept of air-based energy storage power generation technology is to compress and store air when there is excess electricity, and release the stored compressed air to drive a turbine to generate electricity when energy demand increases. This energy storage method has high power density and a long storage period, and can provide continuous power output during peak demand periods in the power system, effectively solving the problems of intermittency and volatility in renewable energy power generation. However, existing air-based energy storage injection-production packers face some technical challenges. First, insufficient sealing performance may lead to leakage of stored air, reducing system efficiency and energy storage capacity. Second, air-based energy storage generally uses salt caverns as energy storage containers and compressed air as the energy storage medium, thus exhibiting environmental characteristics such as high humidity, high salinity, and high oxygen content, posing a significant challenge to the corrosion resistance of the injection-production tubing. Furthermore, air energy storage systems typically have a service life of 20-30 years, during which they store and release energy daily, thus placing high demands on the long-term sealing performance of the injection and production tubing. With the construction of MW-level demonstration projects such as the 300MW compressed air energy storage power station in Yingcheng, Hubei, it has been found that laser cladding alloy anti-corrosion coatings for the exposed ends of injection and production well casing offer high reliability and economy. However, the anti-corrosion treatment of the airtight threads of the casing still presents many challenges. Therefore, developing a laser cladding method for the anti-corrosion treatment of airtight casing threads is essential.

[0003] This invention provides a laser cladding method for corrosion protection of airtight sleeve threads. The implementation of this invention will further improve the long-term corrosion protection and sealing performance of air storage injection and production tubing, providing an economical and effective solution for the large-scale application of renewable energy and the efficient operation of power systems. Summary of the Invention

[0004] The laser cladding method for corrosion protection of airtight sleeve threads described in this invention mainly includes a corrosion protection processing method for the sealing end face of airtight threaded couplings and a corrosion protection processing method for the airtight threaded end face of pipe ends.

[0005] The present invention relates to the following specific method:

[0006] The anti-corrosion processing method for the sealing end face of the airtight threaded coupling is as follows: the coupling blank is rough machined to remove 0.7-1mm more material than the final product. Then, laser cladding is performed on the sealing end face of the airtight threaded coupling. The cladding material is 625 nickel-based alloy, and the cladding thickness is 1-1.5mm. Then, the cladding layer is rough machined and finish machined according to the size requirements of the airtight threaded coupling. Finally, annealing treatment is performed to form the sealing end face of the coupling with the 625 nickel-based alloy cladding layer.

[0007] The anti-corrosion processing method for the airtight thread end face of the pipe end is as follows: the rough machining of the pipe end requires removing 0.7-1mm more material than the final product. Then, laser cladding is performed on the airtight thread end face of the pipe end using 625 nickel-based alloy as the cladding material, with a cladding thickness of 1-1.5mm. Subsequently, the cladding additive is rough-machined and finish-machined according to the dimensions of the airtight thread of the pipe end, followed by annealing treatment, finally forming a pipe end sealing end face with a 625 nickel-based alloy cladding layer.

[0008] The steps for laser cladding of 625 nickel-based alloy are as follows: First, the workpiece is ultrasonically cleaned for 5-10 minutes, followed by drying. The laser cladding parameters are: laser power of 300W-600W, laser scanning speed of 4mm / s-14mm / s, alloy powder conveying speed of 3g / min-10g / min, and scanning overlap rate of 15%-35%. The 625 nickel-based alloy powder also contains 0.1-0.3wt% nickel-coated graphite powder, which is composed of the following mass fractions: 10%-40% graphite and 60%-90% Ni.

[0009] The rough turning method involves removing the high-porosity layer on the upper surface of the laser-clad end face. This requires a rough turning tool made of carbide with a tool tip radius of R0.8-1.2mm, a machine tool speed of 80-90 rpm, and a tool feed rate of approximately 0.03-0.05mm.

[0010] The finishing method involves performing fine surface machining after rough turning. The remaining thickness of the 625 nickel-based alloy after finishing turning should not be less than 0.5mm. Due to the poor heat dissipation performance of 625 nickel-based alloy, the use of carbide tools results in severe wear. Therefore, ceramic finishing tools are required, with a tool tip radius of R0.2-0.4mm, a machine tool speed of 90-100 rpm, and a tool feed rate of 0.06-0.08mm.

[0011] The annealing process is as follows: annealing temperature is 350-400℃, annealing time is 0.5-1h, annealing atmosphere is carbon-containing gas, carbon-containing gas pressure is 500-1000Pa, and carburizing gas is acetylene.

[0012] Long corrosion protection life: Due to the short duration of heat input on the substrate during laser cladding and the concentrated laser energy, a good metallurgical bond can be achieved between the substrate and the coating material, resulting in a high bonding strength compared to other coating corrosion protection methods. Furthermore, the method described in this invention effectively avoids the drawbacks of increased thickness due to the cladding layer covering the sealing end face, which could affect the contact sealing effect. By treating key sealing locations with corrosion protection and combining it with laser cladding corrosion protection technology on the inner wall of the pipe, the corrosion sealing problem of the pipe string can be effectively solved, avoiding excessive costs associated with using expensive corrosion protection materials for the entire pipe assembly.

[0013] Improved airtightness: Based on the improved corrosion resistance of 625 nickel-based alloy, graphite is added to the cladding layer. The use of nickel-coated graphite can avoid the oxidation and deformation of graphite during the cladding process. After turning, some graphite is exposed on the cross-section. After subsequent annealing in a carbon-containing atmosphere, the graphite particles on the exposed surface grow further, making the graphite slightly protrude from the turned surface. Therefore, after threaded connection, a "micro-maze" structure composed of graphite protrusions is formed on the connection contact surface, further improving the sealing performance. Detailed Implementation

[0014] Example 1:

[0015] The anti-corrosion processing method for the sealing end face of the airtight threaded coupling is as follows: the coupling blank is rough machined to remove more than 0.8mm of material than the final product. Then, laser cladding is performed on the sealing end face of the airtight threaded coupling. The cladding material is 625 nickel-based alloy with a cladding thickness of 1.2mm. Then, the cladding layer is rough machined and finish machined according to the size requirements of the airtight threaded coupling. Finally, annealing treatment is performed to form the sealing end face of the coupling with a 625 nickel-based alloy cladding layer.

[0016] The anti-corrosion processing method for the airtight thread end face of the pipe end is as follows: the rough machining of the pipe end is to remove more than 0.8mm of material than the final product. Then, laser cladding is performed on the airtight thread end face of the pipe end. The cladding material is 625 nickel-based alloy and the cladding thickness is 1.2mm. Then, according to the pipe end airtight thread size requirements, the cladding additive is rough-machined and fine-machined. Finally, annealing treatment is performed to form a pipe end sealing end face with a 625 nickel-based alloy cladding layer.

[0017] The steps for laser cladding of 625 nickel-based alloy are as follows: First, the workpiece is ultrasonically cleaned for 8 minutes, followed by drying. The laser cladding parameters are: laser power of 500W, laser scanning speed of 9mm / s, alloy powder feeding speed of 7g / min, scanning overlap rate of 20%, and the 625 nickel-based alloy powder also contains 0.2wt% nickel-coated graphite powder, which is composed of the following mass fractions: 20% graphite and 80% Ni.

[0018] The rough turning method involves removing the high-porosity layer on the upper surface of the laser-clad end face. This requires a rough turning tool made of carbide with a tool tip radius of R1mm, a machine speed of 80 rpm, and a tool feed rate of approximately 0.04mm.

[0019] The finishing method involves performing surface finishing after roughing, using a ceramic finishing tool with a tool tip radius of 0.3mm, a machine speed of 100 rpm, and a tool feed rate of 0.07mm.

[0020] The annealing process is as follows: annealing temperature is 380℃, annealing time is 0.5h, annealing atmosphere is carbon-containing gas, carbon-containing gas pressure is 800Pa, and carburizing gas is acetylene.

[0021] Accelerated Corrosion Simulation: The airtight threaded coupling and pipe end were placed in the experimental environment, which was set at a simulated experimental temperature of 50℃, a pressure of 12MPa, and an oxygen concentration of 50%. The workpiece was sprayed with a corrosive solution. The corrosive solution simulated formation water, with 1L containing 297g NaCl + 9.05g Na₂SO₄ + 0.69g CaCl₂ + 0.02g MgCl₂. Airtightness Test: After the threaded connection was completed, the two ends were connected with plugs to form a test cascade. A high-pressure air pump was used as both the air and pressure source, connected to both ends of the cascade to provide pressure at 35MPa. The test cascade was placed in a water tank. After the high-pressure air pump was activated, no bubbles were observed escaping from the threaded connection to determine if there was any gas leakage in the test sample. The test results are shown in Table 1.

[0022] Example 2:

[0023] The anti-corrosion processing method for the sealing end face of the airtight threaded coupling is as follows: the coupling blank is rough machined to remove more than 0.8mm of material than the final product. Then, laser cladding is performed on the sealing end face of the airtight threaded coupling. The cladding material is 625 nickel-based alloy with a cladding thickness of 1.2mm. Then, the cladding layer is rough machined and finish machined according to the size requirements of the airtight threaded coupling. Finally, annealing treatment is performed to form the sealing end face of the coupling with a 625 nickel-based alloy cladding layer.

[0024] The anti-corrosion processing method for the airtight thread end face of the pipe end is as follows: the rough machining of the pipe end is to remove more than 0.8mm of material than the final product. Then, laser cladding is performed on the airtight thread end face of the pipe end. The cladding material is 625 nickel-based alloy and the cladding thickness is 1.2mm. Then, according to the pipe end airtight thread size requirements, the cladding additive is rough-machined and fine-machined. Finally, annealing treatment is performed to form a pipe end sealing end face with a 625 nickel-based alloy cladding layer.

[0025] The steps for laser cladding of 625 nickel-based alloy are as follows: First, the workpiece is ultrasonically cleaned for 6 minutes, followed by drying. The laser cladding parameters are: laser power of 400W, laser scanning speed of 8mm / s, alloy powder feeding speed of 5g / min, scanning overlap rate of 30%, and the 625 nickel-based alloy powder also contains 0.2wt% nickel-coated graphite powder, which is composed of the following mass fractions: 25% graphite and 75% Ni.

[0026] The rough turning method involves removing the high-porosity layer on the upper surface of the laser-clad end face. This requires a rough turning tool made of carbide with a tool tip radius of R1mm, a machine speed of 80 rpm, and a tool feed rate of approximately 0.04mm.

[0027] The finishing method involves performing surface finishing after roughing, using a ceramic finishing tool with a tool tip radius of 0.3mm, a machine speed of 100 rpm, and a tool feed rate of 0.07mm.

[0028] The annealing process is as follows: annealing temperature is 360℃, annealing time is 0.75h, annealing atmosphere is carbon-containing gas, carbon-containing gas pressure is 600Pa, and carburizing gas is acetylene.

[0029] The testing process is described in Example 1, and the test results are shown in Table 1.

[0030] Comparative Example 1:

[0031] The anti-corrosion processing method for the sealing end face of the airtight threaded coupling is as follows: the coupling blank is rough machined to remove more than 0.8mm of material than the final product. Then, laser cladding is performed on the sealing end face of the airtight threaded coupling. The cladding material is 625 nickel-based alloy with a cladding thickness of 1.2mm. Then, the cladding layer is rough machined and finish machined according to the size requirements of the airtight threaded coupling. Finally, annealing treatment is performed to form the sealing end face of the coupling with a 625 nickel-based alloy cladding layer.

[0032] The anti-corrosion processing method for the airtight thread end face of the pipe end is as follows: the rough machining of the pipe end is to remove more than 0.8mm of material than the final product. Then, laser cladding is performed on the airtight thread end face of the pipe end. The cladding material is 625 nickel-based alloy and the cladding thickness is 1.2mm. Then, according to the pipe end airtight thread size requirements, the cladding additive is rough-machined and fine-machined. Finally, annealing treatment is performed to form a pipe end sealing end face with a 625 nickel-based alloy cladding layer.

[0033] The steps for laser cladding of 625 nickel-based alloy are as follows: First, the workpiece is ultrasonically cleaned for 8 minutes, followed by drying. The laser cladding parameters are: laser power of 500W, laser scanning speed of 9mm / s, alloy powder feeding speed of 7g / min, and scanning overlap rate of 20%.

[0034] The rough turning method involves removing the high-porosity layer on the upper surface of the laser-clad end face. This requires a rough turning tool made of carbide with a tool tip radius of R1mm, a machine speed of 80 rpm, and a tool feed rate of approximately 0.04mm.

[0035] The finishing method involves performing surface finishing after roughing, using a ceramic finishing tool with a tool tip radius of 0.3mm, a machine speed of 100 rpm, and a tool feed rate of 0.07mm.

[0036] The annealing process is as follows: annealing temperature is 380℃, annealing time is 0.5h, annealing atmosphere is carbon-containing gas, carbon-containing gas pressure is 800Pa, and carburizing gas is acetylene.

[0037] Comparative Example 2:

[0038] The anti-corrosion processing method for the sealing end face of the airtight threaded coupling is as follows: the coupling blank is rough machined to remove more than 0.8mm of material than the final product. Then, laser cladding is performed on the sealing end face of the airtight threaded coupling. The cladding material is 625 nickel-based alloy with a cladding thickness of 1.2mm. Then, the cladding layer is rough machined and finish machined according to the size requirements of the airtight threaded coupling. Finally, annealing treatment is performed to form the sealing end face of the coupling with a 625 nickel-based alloy cladding layer.

[0039] The anti-corrosion processing method for the airtight thread end face of the pipe end is as follows: the rough machining of the pipe end requires removing more than 0.8mm of material than the final product. Then, laser cladding is performed on the airtight thread end face of the pipe end using 625 nickel-based alloy as the cladding material and cladding thickness of 1.2mm. Subsequently, the cladding additive is rough-machined and finish-machined according to the dimensions of the airtight thread of the pipe end, finally forming a pipe end sealing end face with a 625 nickel-based alloy cladding layer.

[0040] The steps for laser cladding of 625 nickel-based alloy are as follows: First, the workpiece is ultrasonically cleaned for 8 minutes, followed by drying. The laser cladding parameters are: laser power of 500W, laser scanning speed of 9mm / s, alloy powder feeding speed of 7g / min, scanning overlap rate of 20%, and the 625 nickel-based alloy powder also contains 0.2wt% nickel-coated graphite powder, which is composed of the following mass fractions: 20% graphite and 80% Ni.

[0041] The rough turning method involves removing the high-porosity layer on the upper surface of the laser-clad end face. This requires a rough turning tool made of carbide with a tool tip radius of R1mm, a machine speed of 80 rpm, and a tool feed rate of approximately 0.04mm.

[0042] The finishing method involves performing surface finishing after roughing, using a ceramic finishing tool with a tool tip radius of 0.3mm, a machine speed of 100 rpm, and a tool feed rate of 0.07mm.

[0043] Comparative Example 3:

[0044] The anti-corrosion processing method for the sealing end face of the airtight threaded coupling is as follows: the coupling blank is rough machined to remove more than 0.8mm of material than the final product. Then, laser cladding is performed on the sealing end face of the airtight threaded coupling. The cladding material is 625 nickel-based alloy with a cladding thickness of 1.2mm. Then, the cladding layer is rough machined and finish machined according to the size requirements of the airtight threaded coupling. Finally, annealing treatment is performed to form the sealing end face of the coupling with a 625 nickel-based alloy cladding layer.

[0045] The anti-corrosion processing method for the airtight thread end face of the pipe end is as follows: the rough machining of the pipe end is to remove more than 0.8mm of material than the final product. Then, laser cladding is performed on the airtight thread end face of the pipe end. The cladding material is 625 nickel-based alloy and the cladding thickness is 1.2mm. Then, according to the pipe end airtight thread size requirements, the cladding additive is rough-machined and fine-machined. Finally, annealing treatment is performed to form a pipe end sealing end face with a 625 nickel-based alloy cladding layer.

[0046] The steps for laser cladding of 625 nickel-based alloy are as follows: First, the workpiece is ultrasonically cleaned for 8 minutes, followed by drying. The laser cladding parameters are: laser power of 500W, laser scanning speed of 9mm / s, alloy powder feeding speed of 7g / min, scanning overlap rate of 20%, and the 625 nickel-based alloy powder also contains 0.2wt% nickel-coated graphite powder, which is composed of the following mass fractions: 20% graphite and 80% Ni.

[0047] The rough turning method involves removing the high-porosity layer on the upper surface of the laser-clad end face. This requires a rough turning tool made of carbide with a tool tip radius of R1mm, a machine speed of 80 rpm, and a tool feed rate of approximately 0.04mm.

[0048] The finishing method involves performing surface finishing after roughing, using a ceramic finishing tool with a tool tip radius of 0.3mm, a machine speed of 100 rpm, and a tool feed rate of 0.07mm.

[0049] The annealing process is as follows: annealing temperature is 300℃, annealing time is 0.3h, annealing atmosphere is carbon-containing gas, carbon-containing gas pressure is 800Pa, and carburizing gas is acetylene.

[0050] Comparative Example 4:

[0051] The anti-corrosion processing method for the sealing end face of the airtight threaded coupling is as follows: the coupling blank is rough machined to remove more than 0.8mm of material than the final product. Then, laser cladding is performed on the sealing end face of the airtight threaded coupling. The cladding material is 625 nickel-based alloy with a cladding thickness of 1.2mm. Then, the cladding layer is rough machined and finish machined according to the size requirements of the airtight threaded coupling. Finally, annealing treatment is performed to form the sealing end face of the coupling with a 625 nickel-based alloy cladding layer.

[0052] The anti-corrosion processing method for the airtight thread end face of the pipe end is as follows: the rough machining of the pipe end is to remove more than 0.8mm of material than the final product. Then, laser cladding is performed on the airtight thread end face of the pipe end. The cladding material is 625 nickel-based alloy and the cladding thickness is 1.2mm. Then, according to the pipe end airtight thread size requirements, the cladding additive is rough-machined and fine-machined. Finally, annealing treatment is performed to form a pipe end sealing end face with a 625 nickel-based alloy cladding layer.

[0053] The steps for laser cladding of 625 nickel-based alloy are as follows: First, the workpiece is ultrasonically cleaned for 8 minutes, followed by drying. The laser cladding parameters are: laser power of 500W, laser scanning speed of 9mm / s, alloy powder feeding speed of 7g / min, scanning overlap rate of 20%, and the 625 nickel-based alloy powder also contains 0.2wt% nickel-coated graphite powder, which is composed of the following mass fractions: 20% graphite and 80% Ni.

[0054] The rough turning method involves removing the high-porosity layer on the upper surface of the laser-clad end face. This requires a rough turning tool made of carbide with a tool tip radius of R1mm, a machine speed of 80 rpm, and a tool feed rate of approximately 0.04mm.

[0055] The finishing method involves performing surface finishing after roughing, using a ceramic finishing tool with a tool tip radius of 0.3mm, a machine speed of 100 rpm, and a tool feed rate of 0.07mm.

[0056] The annealing process is as follows: annealing temperature is 450℃, annealing time is 1.3h, annealing atmosphere is carbon-containing gas, carbon-containing gas pressure is 1200Pa, and carburizing gas is acetylene.

[0057] Table 1 Test Results

[0058]

Claims

1. A laser cladding method for corrosion protection of airtight sleeve threads, comprising a corrosion protection processing method for the sealing end face of an airtight threaded coupling and a corrosion protection processing method for the airtight threaded end face of a pipe end, characterized in that, The anti-corrosion processing method for the sealing end face of the airtight threaded coupling is as follows: the coupling blank is rough machined to remove 0.7-1mm more than the final product. Then, laser cladding is performed on the sealing end face of the airtight threaded coupling. The cladding material is 625 nickel-based alloy. Then, the cladding layer is rough machined and finish machined according to the size requirements of the airtight threaded coupling. Finally, annealing treatment is performed to form the sealing end face of the coupling with the 625 nickel-based alloy cladding layer. The anti-corrosion processing method for the airtight thread end face of the pipe end is as follows: the rough machining of the pipe end requires removing 0.7-1mm more than the final product. Then, laser cladding is performed on the airtight thread end face of the pipe end using 625 nickel-based alloy as the cladding material. The cladding layer is then rough-machined and finish-machined according to the size requirements of the airtight thread of the pipe end, followed by annealing treatment, finally forming a pipe end sealing end face with a 625 nickel-based alloy cladding layer. The steps for laser cladding of 625 nickel-based alloy are as follows: First, the workpiece is ultrasonically cleaned and then dried. The parameters for laser cladding are: laser power of 300w-600w, laser scanning speed of 4mm / s-14mm / s, alloy powder conveying speed of 3g / min-10g / min, scanning overlap rate of 15%-35%, and 625 nickel-based alloy powder also contains 0.1-0.3wt% nickel-coated graphite powder. The annealing process is as follows: annealing temperature is 350-400℃, annealing time is 0.5-1h, annealing atmosphere is carbon-containing gas, and carbon-containing gas pressure is 500-1000Pa.

2. The method as described in claim 1, characterized in that, Nickel-coated graphite powder is composed of the following components by mass fraction: 10%-40% graphite and 60%-90% Ni.

3. The method as described in claim 1, characterized in that, The roughing method is as follows: the tool tip radius is R0.8-1.2mm, the machine tool speed is 80-90 rpm, and the tool feed rate is 0.03-0.05mm.

4. The method as described in claim 3, characterized in that, Roughing tools made of carbide are used for roughing.

5. The method as described in claim 1, wherein the finishing turning method is to perform surface finishing after rough turning, the remaining thickness of the 625 nickel-based alloy after finishing turning is not less than 0.5mm, the tool tip radius R is 0.2-0.4mm, the machine tool speed is 90-100 rpm, and the tool feed rate is 0.06-0.08mm.

6. The method as described in claim 5, characterized in that, The finishing tool is made of ceramic material.

7. The method as described in claim 1, characterized in that, The carburizing gas is acetylene.

8. The method as described in claim 1, characterized in that, The ultrasonic cleaning time is 5-10 minutes.

9. The method as described in claim 1, characterized in that, In the corrosion protection processing method for the sealing end face of airtight threaded couplings, the thickness of the cladding layer is 1-1.5mm.

10. The method as described in claim 1, characterized in that, The anti-corrosion processing method for the airtight threaded end face of the pipe end has a cladding layer thickness of 1-1.5mm.

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