Method for improving heat transfer performance and fatigue performance of nickel-based heat transfer tube weldment through electromagnetic coupling energy field

Abstract

The invention relates to the technical field of nuclear reaction equipment production and processing, and particularly discloses a method for improving the heat transfer performance and fatigue performance of a nickel-based heat transfer pipe welding part through an electromagnetic coupling energy field to solve the problems that excessive heat damage, deformation and the like are likely to be generated in an existing nickel-based heat transfer pipe welding part strengthening treatment means. Comprising the following steps: fixing a welding part in the center of an electromagnetic coupling generation device; setting equipment parameters, applying a pulsed electric field, and stopping device operation when the temperature of a welding area of a welding part reaches 150 DEG C or above after the pulsed electric field is applied for multiple times; setting equipment parameters, applying a pulsed magnetic field, and carrying out electromagnetic coupling treatment; and then the electromagnetic coupling generating device is separated, and the welding part is taken out. The pulsed electric field is firstly applied to the welding part, then the pulsed magnetic field is applied, the temperature of the welding area of the welding part is increased through the first applied electric field and the Joule heating effect, the microstructure defects are repaired more obviously through the electromagnetic field under the high-temperature condition, and the heat transfer performance and the fatigue performance of the welding part can be remarkably improved.

Description

Technical Field

[0001] This invention relates to the field of nuclear reaction equipment manufacturing and processing technology, and more specifically, to a method for improving the heat transfer performance and fatigue performance of nickel-based heat transfer tube welded components using an electromagnetic coupling energy field. Background Technology

[0002] The steam generator is the core heat exchange equipment in a nuclear reactor. Its primary function is to transfer the heat generated by the fission of nuclear fuel in the primary loop to the water in the secondary loop, producing high-temperature, high-pressure steam to drive a turbine for power generation. Simultaneously, it ensures complete isolation between the primary and secondary loops, preventing the leakage of radioactive materials. Nickel-based heat transfer tubes, as a critical component of the steam generator in a nuclear reactor, directly affect the heat exchange efficiency and service life of the steam generator due to their thermal conductivity and fatigue performance. Currently, the heat transfer tubes of steam generators are directly formed by cold rolling. However, the manufacturing capabilities of cold rolling equipment limit the length of the heat transfer tubes to some extent; therefore, welding is used to connect long heat transfer tubes.

[0003] For example, patent CN104046759A proposes a cold working process for 800 alloy heat transfer tubes used in nuclear power steam generators, including cold rolling of the billet, intermediate annealing, final cold rolling, and finished product annealing. Combined with patent CN108581141A, a welding method for dissimilar materials used in heat transfer tubes for high-temperature gas-cooled reactors is provided. This method utilizes pulsed TIG welding to weld Incoloy-800H and SA-213T22, enabling the connection of long-length heat transfer tubes.

[0004] However, welding, as a rapid heating and solidification non-equilibrium process, introduces residual stress during rapid heating and cooling, leading to defects such as segregation and inclusions. This results in inhomogeneity of the microstructure and properties in the joint area, significantly impacting the overall performance of the welded joint. Therefore, ensuring and improving the service performance of welded joints of nickel-based heat transfer tubes in steam generators is of great practical significance for the safe operation of nuclear power plant equipment.

[0005] Currently, the main methods for strengthening the welded area of ​​nickel-based heat transfer pipes include laser shock blasting and heat treatment. Laser shock blasting uses a high-energy laser beam to bombard the welded area, thereby improving the fatigue life of the weld joint by changing lattice dislocations and grain size and introducing residual compressive stress. However, this technology requires complex equipment and highly skilled operation, resulting in high application costs. Furthermore, laser shock blasting requires a large amount of energy, which may cause excessive thermal damage and deformation. Heat treatment involves placing the welded parts in a high-temperature thermal aging furnace to release residual stress. However, this method requires maintaining a high-temperature environment for a long time, resulting in a long processing cycle, high costs, and significant environmental pollution. The fatigue performance of the welded parts may also be reduced to some extent after heat treatment. Summary of the Invention

[0006] The purpose of this invention is to solve the problems of excessive heat damage and deformation that exist in the current welding strengthening methods for nickel-based heat transfer tubes used in steam generators.

[0007] This invention is achieved through the following technical solution: This invention provides a method for improving the heat transfer and fatigue performance of welded nickel-based heat transfer tubes using an electromagnetically coupled energy field, comprising the following steps: S1 fixes the nickel-based heat transfer tube weldment to the center of the electromagnetic coupling generator; S2 sets the equipment parameters of the electromagnetic coupling generator, applies a pulsed electric field, and after multiple pulsed electric fields, stops the device when the temperature of the welding area of ​​the nickel-based heat transfer tube weldment reaches 150°C or above. S3 Then set the equipment parameters of the electromagnetic coupling generator, apply a pulsed magnetic field, and perform electromagnetic coupling processing; S4 After the above process is completed, the electromagnetic coupling generator is separated and the nickel-based heat transfer tube weldment is removed.

[0008] Preferably, in step S2, the device parameters when applying the pulsed electric field are: voltage 1-2V and electric pulse frequency 30-80Hz.

[0009] Preferably, in step S3, the equipment parameters for applying the pulsed magnetic field are: voltage 0-2.0V, magnetic field strength 0-2.0T, electrical pulse frequency 30-80Hz, magnetic pulse duration 10s-20s, and number of magnetic pulses 15-20.

[0010] The present invention also provides the above-mentioned electromagnetic coupling generating device, including a pulse electric field generating device, a pulse magnetic field generating device, and an external PLC system. The pulse electric field generating device includes two electrodes, the pulse magnetic field generating device includes an excitation coil, and the external PLC system can output a pulse current with a current range of 0-10000A, a voltage range of 0-10V, and a pulse magnetic field with a magnetic field strength range of 0-2.5T.

[0011] Preferably, the pulsed electric field generator and the pulsed magnetic field generator are triggered separately to form a single electric field or a single magnetic field; or the pulsed electric field generator and the pulsed magnetic field generator are triggered simultaneously to form an electromagnetically coupled energy field. The technical solution of the present invention has the following beneficial effects: This invention addresses the problems of high stress and microstructural defects (such as inclusions and microcracks) in the welded areas of existing welding strengthening methods for nickel-based heat transfer tubes used in steam generators. It proposes a method using an electromagnetically coupled energy field to enhance the heat transfer and fatigue performance of welded nickel-based heat transfer tubes. Electromagnetic treatment strengthens the welded components by eliminating or mitigating these defects, improving the fatigue performance and heat transfer efficiency of the welded area. This method involves introducing electric and magnetic fields at both ends of the welded component. The thermal effect of the current promotes atomic motion through heating, providing energy for dislocation movement, reducing dislocation pile-up, and promoting reorganization, thus optimizing the microstructure. Simultaneously, Joule heating can locally heat the area around microcracks, prompting the filling of voids or cracks in the material. The Lorentz force and electron wind generated by the electromagnetic field effectively promote dislocation movement, releasing residual stress in the welded area and distributing stress evenly, reducing stress concentration and improving fatigue life. Simultaneously, it promotes M... 23 C6 precipitation reduces lattice distortion of solid solution atoms in nickel-based heat transfer pipe weldments, thereby improving the heat transfer performance of the weldments. Specifically: (1) Electromagnetic coupling treatment of nickel-based heat transfer tube weldments with electromagnetic coupling energy field effectively controls the residual stress of the weldments and improves the tensile strength to a certain extent, thereby improving the fatigue performance of the weldments; in addition, the electromagnetic coupling energy field promotes the movement of dislocations and M 23 The precipitation of C6 reduces lattice distortion and effectively improves the tensile strength and heat transfer performance of welded parts.

[0012] (2) The entire electromagnetic coupling process consumes only electrical energy and does not generate other pollution sources. The entire process is usually kept within 10 minutes. Compared with traditional post-processing methods for welded parts, it has the advantages of high efficiency, no pollution and low cost.

[0013] (3) Before and after electromagnetic coupling treatment, the temperature rise of nickel-based heat transfer tube weldment will not exceed its recrystallization temperature. The electromagnetic coupling energy field will not change the morphological characteristics of the weldment and will not cause damage to the surface of the weldment. It can be applied to heat transfer tube weldment of different sizes and structures.

[0014] This method has advantages such as short processing time, wide adaptability to size and structure, good processing effect and low processing cost. It can effectively solve the problems of high cost, large pollution and reduced fatigue performance of existing nickel-based heat transfer tube welding area strengthening methods. Attached Figure Description

[0015] Figure 1 The image shows a comparison of the residual stress of the nickel-based heat transfer tube weldment before and after treatment in the experimental example. Figure 2 This is a comparison chart of the average yield strength of the nickel-based heat transfer tube welded components in this invention, before and after treatment. Figure 3 This is a comparison chart of the average tensile strength of the nickel-based heat transfer tube welded components in this invention, before and after treatment. Figure 4 This is a comparison chart of the average thermal conductivity of the nickel-based heat transfer tube welded components in this invention, before and after treatment. Detailed Implementation

[0016] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, the technical solutions in the embodiments of the present invention will be clearly and completely described below. Where specific conditions are not specified in the embodiments, they are performed according to conventional conditions or conditions recommended by the manufacturer; where the manufacturers of the instruments, equipment, reagents, or raw materials used are not specified, they are all conventional products that can be purchased commercially.

[0017] This invention provides a method for improving the heat transfer and fatigue performance of welded nickel-based heat transfer tubes using an electromagnetically coupled energy field, specifically comprising the following steps: (1) Using a special fixture, the nickel-based heat transfer tube weldment is fixed in the center of the electromagnetic coupling generator by stepper motors at both ends of the electrode.

[0018] The electromagnetic coupling generating device includes a pulse electric field generating device and a pulse magnetic field generating device, as well as an external PLC system shared by the above devices; The pulse electric field generator includes two electrodes and an external PLC system. The external PLC system can output pulse current with a current range of 0-10000A and a voltage range of 0-10V. The pulsed magnetic field generator includes an excitation coil and an external PLC system. The external PLC system can output a pulsed magnetic field with a magnetic field strength range of 0-2.5T.

[0019] (2) Set the equipment parameters of the electromagnetic coupling generator, such as voltage, magnetic field strength, electric pulse frequency, magnetic pulse time, number of magnetic pulses, etc. First apply the pulse electric field, and after reaching the specified temperature T, apply the pulse magnetic field to perform electromagnetic coupling treatment on the nickel-based heat transfer tube weldment clamped in the center of the electromagnetic coupling generator.

[0020] The external PLC system controls the equipment with a voltage of 1-2V and an electric pulse frequency of 30-80Hz. First, a pulsed electric field is applied. After multiple pulsed electric fields, the temperature of the welding area of ​​the nickel-based heat transfer tube weldment reaches 150℃ or above, and then the equipment stops operating. Then set the voltage to 0-2.0V, the magnetic field strength to 0-2.0T, the electric pulse frequency to 30-80Hz, the magnetic pulse time to 10s-20s, and the number of magnetic pulses to 15-20, apply the pulsed magnetic field, and perform electromagnetic coupling.

[0021] This invention first applies a pulsed electric field to the nickel-based heat transfer tube weldment, and then applies a pulsed magnetic field. The applied electric field utilizes the Joule heating effect to raise the temperature of the welded area of ​​the nickel-based heat transfer tube weldment. The electromagnetic field under high temperature conditions has a more significant effect on repairing microstructural defects, which can significantly improve the heat transfer performance and fatigue performance of the nickel-based heat transfer tube weldment.

[0022] (3) After the above electromagnetic coupling process is completed, the electromagnetic coupling generating device is separated by the drive motor, and the special fixture and nickel-based heat transfer tube welding parts are taken out.

[0023] Example 1 Step 1: Take the nickel-based heat transfer tube weldment and use a special clamp to fix the nickel-based heat transfer tube weldment in the center of the electromagnetic coupling generator through the stepper motors at both ends of the electrode.

[0024] Step 2: Set the electromagnetic field parameters: voltage 1.8V, electric pulse frequency 50Hz. First, apply the electric field, press the start button of the electromagnetic coupling generator, and the electrodes and excitation coil discharge according to the set parameters. After two pulse electric fields, stop the equipment operation and check that the temperature of the nickel-based heat transfer tube welded part reaches 150℃.

[0025] Step 3: Set the electromagnetic field parameters: voltage 1.8V, magnetic field strength 1.5T, electric pulse frequency 50Hz, magnetic pulse time 20s, number of magnetic pulses 15, turn on the cooling device, control the temperature to maintain at 150℃, press the start button of the electromagnetic coupling generator to perform electromagnetic coupling processing, processing time 300s.

[0026] Step 4: The electrodes and excitation coils discharge and demagnetize according to the set parameters. After two pulsed electric fields, the equipment stops operating. After the discharge process is completed, the electromagnetic coupling generator is separated by the drive motor, and the special fixture and nickel-based heat transfer tube weldment are removed. The electromagnetic coupling process is then complete.

[0027] Test case (1) Effect of electromagnetic coupling treatment on residual stress in welded nickel-based heat transfer tubes 1.1 Residual stress detection before treatment Non-destructive testing methods such as ultrasonic testing and X-ray testing were used to locate and test the welding area of ​​the untreated nickel-based heat transfer pipe weldment, and to determine the residual stress distribution in the welding area before electromagnetic coupling treatment.

[0028] 1.2 Electromagnetic Coupling Treatment Another sample of a nickel-based heat transfer tube weldment was subjected to electromagnetic coupling treatment in accordance with the method described in Example 1.

[0029] 1.3 Residual stress detection after treatment The welded nickel-based heat transfer tubes after electromagnetic coupling treatment were subjected to positioning inspection using non-destructive testing methods such as ultrasonic testing and X-ray testing. The residual stress distribution in the welded area before electromagnetic coupling treatment was determined, and the results are as follows: Figure 1 As shown.

[0030] Tests showed that the residual stress of the nickel-based heat transfer tube weldment was reduced to a certain extent after electromagnetic coupling treatment. The average residual stress decreased from 116.8 MPa to 76 MPa, a reduction of 34.93%, indicating that the electromagnetic coupling energy field can effectively release the residual stress of the nickel-based heat transfer tube weldment.

[0031] (2) Effect of electromagnetic coupling treatment on tensile properties of nickel-based heat transfer tube welded parts Two nickel-based heat transfer tube welded components were selected as the control group, without any treatment; two other nickel-based heat transfer tube welded components were selected as the experimental group, and electromagnetic coupling treatment was performed according to the method in Example 1. The yield strength and tensile strength of the nickel-based heat transfer tube welded components in the control and experimental groups were tested using a tensile testing machine, and the results are as follows. Figure 2 and Figure 3 As shown.

[0032] Tests showed that the average yield strength and average tensile strength of the nickel-based heat transfer tube welded parts were improved to a certain extent after electromagnetic coupling treatment. The average yield strength increased from 324 MPa to 340 MPa, an increase of 4.9%, and the average tensile strength increased from 747 MPa to 775 MPa, an increase of 3.7%. This indicates that the electromagnetic coupling energy field can improve the tensile properties of the nickel-based heat transfer tube welded parts, thereby improving their fatigue performance.

[0033] (3) Effect of electromagnetic coupling treatment on the heat transfer performance of nickel-based heat transfer tube welded parts Two nickel-based heat transfer tube welded components were selected as the control group, without any treatment; two other nickel-based heat transfer tube welded components were selected as the experimental group, and electromagnetic coupling treatment was performed according to the method in Example 1. The thermal conductivity of the nickel-based heat transfer tube welded components in the control and experimental groups was tested by laser flash analysis, and the results are as follows. Figure 4 As shown.

[0034] Tests showed that the average thermal conductivity of the nickel-based heat transfer tube weldment was improved to a certain extent after electromagnetic coupling treatment, increasing from 15.559 W / (m·K) to 17.841 W / (m·K), an increase of 14.7%. This indicates that the electromagnetic coupling energy field can improve the thermal conductivity of the nickel-based heat transfer tube weldment, thereby improving its heat transfer performance in the steam generator.

[0035] The above are merely preferred embodiments of the present invention and are not intended to limit the present invention. Various modifications and variations can be made to the present invention by those skilled in the art. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the scope of protection of the present invention.

Claims

1. A method for improving the heat transfer performance and fatigue performance of welded nickel-based heat transfer tubes using an electromagnetically coupled energy field, characterized in that, Includes the following steps: S1 fixes the nickel-based heat transfer tube weldment to the center of the electromagnetic coupling generator; S2 sets the equipment parameters of the electromagnetic coupling generator, applies a pulsed electric field, and after multiple pulsed electric fields, stops the device when the temperature of the welding area of ​​the nickel-based heat transfer tube weldment reaches 150°C or above. S3 Then set the equipment parameters of the electromagnetic coupling generator, apply a pulsed magnetic field, and perform electromagnetic coupling processing; S4 After the above process is completed, the electromagnetic coupling generator is separated and the nickel-based heat transfer tube weldment is removed.

2. The method for improving the heat transfer performance and fatigue performance of nickel-based heat transfer tube weldments using an electromagnetic coupling energy field according to claim 1, characterized in that, In step S2, the device parameters for applying the pulsed electric field are: voltage 1-2V and pulse frequency 30-80Hz.

3. The method for improving the heat transfer performance and fatigue performance of nickel-based heat transfer tube weldments using an electromagnetic coupling energy field according to claim 1, characterized in that, In step S3, the equipment parameters for applying the pulsed magnetic field are: voltage 0-2.0V, magnetic field strength 0-2.0T, electric pulse frequency 30-80Hz, magnetic pulse duration 10s-20s, and number of magnetic pulses 15-20.

4. An electromagnetic coupling generating device according to claim 1, characterized in that, It includes a pulse electric field generator, a pulse magnetic field generator, and an external PLC system. The pulse electric field generator includes two electrodes, the pulse magnetic field generator includes an excitation coil, and the external PLC system can output pulse current with a current range of 0-10000A, a voltage range of 0-10V, and a pulse magnetic field with a magnetic field strength range of 0-2.5T.

5. The electromagnetic coupling generating device according to claim 4, characterized in that, The pulsed electric field generator and the pulsed magnetic field generator are triggered individually to form a single electric field or a single magnetic field; or the pulsed electric field generator and the pulsed magnetic field generator are triggered simultaneously to form an electromagnetically coupled energy field.

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