A production and preparation method for eliminating internal stress in a copper-steel bimetallic composite material

Abstract

The present invention discloses a production and preparation method for eliminating internal stress in a copper-steel bimetallic composite material. The method includes: preparing the copper-steel bimetallic composite material using additive manufacturing technology; adding alloying elements at the copper-steel interface to promote the diffusion and uniform distribution of elements; during the additive manufacturing process, adjusting the cooling rate to refine the grains at the interface; performing heat treatment on the copper-steel bimetallic composite material after additive manufacturing; performing ultrasonic impact treatment on the heat-treated copper-steel bimetallic composite material; performing vibration treatment on the copper-steel bimetallic composite material after ultrasonic impact treatment; detecting the distribution of internal stress through ultrasonic detection technology to ensure that the internal stress in the copper-steel bimetallic composite material is effectively eliminated. The method of the present invention can effectively eliminate the internal stress in the copper-steel bimetallic composite material, significantly improve the fatigue resistance, mechanical properties and service life of the material, and ensure the stability and reliability of the material in practical applications.

Description

Technical Field

[0001] The present invention relates to the technical field of metal preparation, and particularly to a production preparation method for eliminating internal stress in a copper-steel bimetal composite material. Background Art

[0002] Due to the excellent electrical conductivity, thermal conductivity of copper and high strength of steel, the copper-steel bimetal composite material has broad application prospects in many fields. However, in the traditional preparation process of manufacturing the copper-steel bimetal composite material, segregation is likely to occur at the copper-steel interface, resulting in the accumulation of residual stress, which affects the mechanical properties and service life of the material. The existence of this residual stress will not only reduce the fatigue resistance of the material, but may also lead to early failure of the material during use.

[0003] At present, the methods for eliminating residual stress mainly include heat treatment and machining, etc. Although heat treatment can effectively release residual stress, it may lead to a decline in material properties, and the treatment process is complex and costly. Mechanical processing methods such as shot peening and ultrasonic impact treatment, although they can generate beneficial residual compressive stress on the material surface, for the complex multi-layer structure of the copper-steel bimetal composite material, their effects are limited and it is difficult to process uniformly. In addition, these methods also have certain limitations in practical applications. For example, heat treatment may cause grain growth of the material, thereby reducing the strength and hardness of the material, while mechanical processing methods may cause damage to the material surface, affecting the surface quality of the material.

[0004] In recent years, with the development of additive manufacturing technology, it has been applied to a certain extent in the preparation of copper-steel bimetal composite materials. Additive manufacturing technology can achieve the rapid manufacturing of complex structures and effectively reduce metallurgical defects at the interface by precisely controlling the heat input and cooling rate during the forming process. However, although additive manufacturing technology has improved the interface bonding quality to a certain extent, residual stress may still be generated during the preparation process, especially at the copper-steel interface. The existence of this residual stress may lead to early failure of the material.

[0005] In summary, developing a production preparation method that can effectively eliminate the internal stress in the copper-steel bimetal composite material is of great significance for improving the performance and service life of the material. Summary of the Invention

[0006] The purpose of the present invention is to propose a production preparation method for eliminating the internal stress in the copper-steel bimetal composite material to solve the problem that the residual stress in the prior art cannot be eliminated thoroughly, affecting the material properties and service life.

[0007] To achieve the above purpose, the present invention adopts the following technical scheme: A production preparation method for eliminating the internal stress in the copper-steel bimetal composite material, comprising the following steps:

[0008] Step S1, prepare the copper-steel bimetallic composite material by additive manufacturing technology, and regulate the interfacial microstructure by controlling the heat source parameters and scanning path;

[0009] Step S2, add alloying elements at the copper-steel interface to promote the diffusion and uniform distribution of elements and reduce the segregation phenomenon at the interface;

[0010] Step S3, during the additive manufacturing process, refine the grains at the interface by adjusting the cooling rate to reduce the stress concentration caused by the grain size difference;

[0011] Step S4, perform heat treatment on the copper-steel bimetallic composite material after additive manufacturing is completed, and eliminate internal stress by controlling the heat treatment temperature and time;

[0012] Step S5, perform ultrasonic impact treatment on the heat-treated copper-steel bimetallic composite material, and make the composite material undergo compressive plastic deformation through high-frequency impact to release residual stress;

[0013] Step S6, perform vibration treatment on the copper-steel bimetallic composite material after ultrasonic impact treatment, and make the material vibrate at the resonance frequency to release stress;

[0014] Step S7, detect the distribution of internal stress through ultrasonic testing technology to ensure that the internal stress of the copper-steel bimetallic composite material is effectively eliminated.

[0015] Furthermore, in step S1, the following sub-steps are also included:

[0016] S1-1, select the additive manufacturing technology according to the application requirements and performance requirements of the copper-steel bimetallic composite material, and the additive manufacturing technology includes laser additive manufacturing, electron beam additive manufacturing, and arc additive manufacturing;

[0017] S1-2, design the scanning path and heat source parameters to regulate the interfacial microstructure, and the heat source parameters include laser power, scanning speed, electron beam energy, and arc current;

[0018] S1-3, monitor the forming state and interface quality of the material in real time, detect the molten pool temperature, molten pool size, and interlayer bonding condition of the material by using a laser displacement sensor and a thermal imager, and adjust the heat source parameters.

[0019] Furthermore, in step S2, the following sub-steps are also included:

[0020] S2-1, add appropriate alloying elements at the copper-steel interface, which can form solid solutions or intermetallic compounds with copper and steel to promote the diffusion and uniform distribution of elements, and the alloying elements include nickel, chromium, molybdenum, iron, manganese, and silicon;

[0021] S2-2. By optimizing the addition amount of alloying elements, controlling the chemical composition gradient at the interface, and reducing the interfacial segregation phenomenon caused by composition differences, the addition amount is 0.5% to 5% of the total weight at the copper-steel interface;

[0022] S2-3. By using stirring, vibration, and electroless plating methods, make the alloying elements evenly distributed at the interface. The stirring time is 10 minutes to 30 minutes, and the rated frequency of the vibration is 20 Hz to 50 Hz.

[0023] Furthermore, in step S3, the following sub-steps are also included:

[0024] S3-1. During the additive manufacturing process, by controlling the temperature and flow rate of the cooling medium, adjusting the cooling rate, and making the grains at the interface refined. The temperature of the cooling medium is controlled at 20°C to 40°C, and the flow rate is 1 L / min to 5 L / min;

[0025] S3-2. During the cooling process, use a multi-point temperature sensor to monitor the temperature change at the interface in real time, and dynamically adjust the cooling parameters according to the monitoring data to ensure that the cooling process is uniform and stable, and avoid interface defects caused by local overcooling or overheating;

[0026] S3-3. After the cooling is completed, conduct a metallographic analysis on the cooled material to check the grain size and tissue uniformity at the interface. The metallographic analysis uses an optical microscope.

[0027] Furthermore, in step S4, the following sub-steps are also included:

[0028] S4-1. Put the copper-steel bimetallic composite material after additive manufacturing into a heat treatment furnace, and heat it to the preset heat treatment temperature at a certain heating rate. The heating rate is 10°C / min to 30°C / min, and the temperature is 500°C to 700°C;

[0029] S4-2. Keep it at the heat treatment temperature for a certain time to fully release the residual stress inside the material. The time is 1 hour to 4 hours;

[0030] S4-3. According to the performance requirements of the material and the heat treatment effect, adjust the heat treatment temperature and holding time within the adjustment range. The adjustment range is the heat treatment temperature ±50°C, and the holding time ±1 hour;

[0031] S4-4. After the holding is completed, cool the material to room temperature at a certain cooling rate. The cooling rate is 10°C / min to 50°C / min.

[0032] Furthermore, in step S5, the following sub-steps are also included:

[0033] S5-1. Adjust the parameters of the ultrasonic impact device according to the thickness and hardness of the material. The parameters include amplitude, frequency, and impact force. The amplitude is from 10 μm to 50 μm, the frequency is from 20 kHz to 50 kHz, and the impact force is from 100 N to 500 N.

[0034] S5-2. Perform ultrasonic impact treatment on the surface of the copper-steel bimetallic composite material according to the preset impact path and number of impacts, causing compressive plastic deformation on the material surface, eliminating surface residual tensile stress, and forming beneficial residual compressive stress on the surface. The number of impacts is from 4 to 10 times.

[0035] S5-3. During the ultrasonic impact treatment process, use strain gauges and displacement sensors to monitor the stress changes and deformation conditions on the material surface, and adjust the impact parameters in real time to ensure uniform and effective impact treatment.

[0036] Further, in step S6, the following sub-steps are also included:

[0037] S6-1. Adjust the vibration frequency and amplitude of the vibration aging device according to the structure and size of the copper-steel bimetallic composite material to match its resonance frequency. The vibration frequency is from 10 Hz to 50 Hz, and the amplitude is from 0.1 mm to 1 mm.

[0038] S6-2. Fix the material on the vibration aging device and perform vibration treatment on the material to make it vibrate at the resonance frequency and release internal residual stress.

[0039] S6-3. During the vibration treatment process, monitor the stress changes and vibration response of the material in real time, and use acceleration sensors and strain gauges to record vibration data to ensure the uniformity and effectiveness of the vibration treatment.

[0040] S6-4. Dynamically adjust the vibration parameters according to the monitoring results to ensure that the material is vibrated under the best resonance conditions to release internal stress to the maximum extent.

[0041] Further, in step S7, the following sub-steps are also included:

[0042] S7-1. Adopt ultrasonic detection technology, set detection parameters, and perform internal stress detection on the treated copper-steel bimetallic composite material. The detection parameters include frequency, pulse width, gain, probe angle, and coupling medium.

[0043] S7-2. During the detection process, record the stress distribution of the material, use ultrasonic signal analysis software to analyze the data, evaluate the stress elimination effect, and determine whether the internal stress of the material is within the controllable range.

[0044] S7-3. If the test result shows that the internal stress exceeds the controllable range, repeat steps S4-S6 to further optimize and adjust the production preparation process until the internal stress is effectively eliminated and the material properties are stable and reliable.

[0045] The beneficial effects brought by the technical solution provided by the present invention at least include:

[0046] The present invention uses additive manufacturing technology to prepare a copper-steel bimetallic composite material. By controlling the heat source parameters and scanning path, the regulation of the interfacial microstructure is realized; alloying elements are added at the copper-steel interface to promote the diffusion and uniform distribution of elements and reduce the segregation phenomenon at the interface; during the additive manufacturing process, by adjusting the cooling rate, the grains at the interface are refined, reducing the stress concentration caused by the grain size difference; after the additive manufacturing of the copper-steel bimetallic composite material is completed, heat treatment is carried out to eliminate the internal stress by controlling the heat treatment temperature and time; after the heat treatment of the copper-steel bimetallic composite material, ultrasonic impact treatment is carried out to make the composite material produce compressive plastic deformation through high-frequency impact and release the residual stress; after the ultrasonic impact treatment of the copper-steel bimetallic composite material, vibration treatment is carried out to make the material vibrate at the resonance frequency and release stress; the distribution of the internal stress is detected by ultrasonic detection technology to ensure that the internal stress of the copper-steel bimetallic composite material is effectively eliminated.

[0047] By optimizing the additive manufacturing process parameters and introducing subsequent treatment processes, the present invention can significantly reduce the residual stress inside the copper-steel bimetallic composite material, effectively eliminate the residual tensile stress inside the material, and form beneficial residual compressive stress on the surface, thereby improving the fatigue resistance and service life of the material.

[0048] The present invention adds an appropriate amount of alloying elements at the copper-steel interface and optimizes the interfacial microstructure through the heat treatment process, significantly improving the metallurgical bonding quality of the interface. It not only reduces the segregation phenomenon at the interface but also enhances the strength and toughness of the interface, significantly improving the overall mechanical properties of the material.

[0049] The production preparation method provided by the present invention has a simple process flow, is easy to operate, does not require complex equipment and high costs, reduces the complex links in the traditional process, reduces the production cost, improves the production efficiency, and has high industrial application value. Description of the Drawings

[0050] In order to more clearly illustrate the technical solutions and advantages in the embodiments of the present invention or the prior art, the following will briefly introduce the drawings required to be used in the description of the embodiments or the prior art. Obviously, the following drawings are only some embodiments of the present invention. For those of ordinary skill in the art, other drawings can be obtained based on these drawings without creative efforts.

[0051] Figure 1 This is the flowchart of the method provided by the embodiment of the present invention. Specific embodiments

[0052] In order to further elaborate on the technical means and effects adopted by the present invention to achieve the predetermined invention purpose, the following combines the accompanying drawings and preferred embodiments to specifically describe the production and preparation method of a copper-steel bimetal composite material that can eliminate internal stress according to the present invention, including its specific implementation manners, structures, features and effects. In the following description, different "one embodiment" or "another embodiment" do not necessarily refer to the same embodiment. In addition, the specific features, structures, or characteristics in one or more embodiments can be combined in any suitable form.

[0053] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by those skilled in the technical field to which the present invention belongs.

[0054] The following embodiments are for illustrative purposes only and are not intended to limit the scope of the present invention.

[0055] The following specifically describes the specific solution of the production and preparation method of a copper-steel bimetal composite material that can eliminate internal stress provided by the present invention with reference to the accompanying drawings.

[0056] Please refer to Figure 1 , which shows the flowchart of the production and preparation method of a copper-steel bimetal composite material that can eliminate internal stress provided by an embodiment of the present invention. The method includes the following steps:

[0057] Step S1: Prepare a copper-steel bimetal composite material using additive manufacturing technology, and regulate the interfacial microstructure by controlling the heat source parameters and scanning paths;

[0058] In step S1, the following sub-steps are further included:

[0059] S1-1: Select additive manufacturing technology according to the application requirements and performance requirements of the copper-steel bimetal composite material. The additive manufacturing technology includes laser additive manufacturing, electron beam additive manufacturing, and arc additive manufacturing;

[0060] S1-2: Design scanning paths and heat source parameters to regulate the interfacial microstructure. The heat source parameters include laser power, scanning speed, electron beam energy, and arc current;

[0061] S1-3: Real-time monitor the forming state and interfacial quality of the material, detect the molten pool temperature, molten pool size, and interlayer bonding condition of the material using a laser displacement sensor and a thermal imager, and adjust the heat source parameters.

[0062] It should be noted that for Laser Additive Manufacturing (LAM): the laser power ranges from 200W to 500W, and the scanning speed ranges from 500mm / min to 1500mm / min. It is applicable to the preparation of high-precision and small-sized copper-steel bimetallic composites. Laser Additive Manufacturing can provide a high energy density, precisely control the molten pool size and temperature, and is suitable for manufacturing complex geometries.

[0063] Electron Beam Additive Manufacturing (EBAM): the electron beam energy ranges from 100W to 300W, and the scanning speed ranges from 300mm / min to 800mm / min. It is applicable to materials that require high energy absorption. Electron Beam Additive Manufacturing can be carried out in a vacuum environment to reduce oxidation and is suitable for manufacturing materials sensitive to the environment.

[0064] Wire Arc Additive Manufacturing (WAAM): the arc current ranges from 80A to 150A, and the welding speed ranges from 200mm / min to 600mm / min. It is applicable to the preparation of large and complex-shaped copper-steel bimetallic composites. Wire Arc Additive Manufacturing has a high deposition efficiency and is suitable for manufacturing large structural parts.

[0065] Laser power: Controls the energy output of the laser, affecting the temperature and size of the molten pool. The laser power range is typically from 200W to 500W.

[0066] Scanning speed: Controls the movement speed of the laser or electron beam on the material surface, affecting the cooling rate and grain size of the molten pool. The scanning speed range is typically from 500mm / min to 1500mm / min.

[0067] Electron beam energy: Controls the energy output of the electron beam, affecting the temperature and size of the molten pool. The electron beam energy range is typically from 100W to 300W.

[0068] Arc current: Controls the energy output of the arc, affecting the temperature and size of the molten pool. The arc current range is typically from 80A to 150A.

[0069] Scanning path: Can be a straight line, spiral line, or complex geometric path. The specific path is optimized according to the shape and performance requirements of the material to ensure uniform forming of the material and metallurgical bonding at the interface.

[0070] Laser displacement sensor: Used to detect the temperature, size of the molten pool, and interlayer bonding condition of the material, and can provide real-time feedback on the three-dimensional size and temperature distribution of the molten pool to ensure the stability and uniformity of the molten pool.

[0071] Thermal imager: Used to monitor the temperature distribution of the molten pool to ensure uniform temperature of the molten pool and avoid local overheating or overcooling.

[0072] Step S2: Add alloying elements at the copper-steel interface to promote the diffusion and uniform distribution of elements and reduce the segregation phenomenon at the interface;

[0073] Among them, in step S2, the following sub-steps are also included:

[0074] S2-1: Add an appropriate amount of alloying elements at the copper-steel interface, which can form solid solutions or intermetallic compounds with copper and steel to promote the diffusion and uniform distribution of elements. The alloying elements include nickel, chromium, molybdenum, iron, manganese, and silicon;

[0075] S2-2: By optimizing the addition amount of alloying elements, control the chemical composition gradient at the interface and reduce the interface segregation phenomenon caused by composition differences. The addition amount is 0.5% to 5% of the total weight at the copper-steel interface;

[0076] S2-3: Adopt stirring, vibration, and electroless plating methods to make the alloying elements uniformly distributed at the interface. The stirring time is 10 minutes to 30 minutes, and the rated vibration frequency is 20 Hz to 50 Hz.

[0077] It should be noted that for nickel: the addition amount is 1% to 3%, which can form a good solid solution with copper and steel, improve the metallurgical compatibility of the interface, and promote the diffusion of elements.

[0078] For chromium: the addition amount is 0.5% to 2%, which can improve the oxidation resistance and corrosion resistance of the material and enhance the hardness and strength of the interface.

[0079] For molybdenum: the addition amount is 0.1% to 1%, which can effectively solid-solution strengthen and precipitate strengthen elements, improve the strength and toughness of the material, and improve the crack resistance of the interface.

[0080] For iron: the addition amount is 0.5% to 2%, which can promote the metallurgical bonding between copper and steel and reduce the brittle phase at the interface.

[0081] For manganese: the addition amount is 0.1% to 1%, which can improve the strength and toughness of the material and improve the crack resistance of the interface.

[0082] For silicon: the addition amount is 0.1% to 0.5%, which can improve the oxidation resistance and corrosion resistance of the material and improve the hardness and strength of the interface.

[0083] Stirring: Adopt mechanical stirring to make the alloying elements uniformly distributed at the interface. The stirring time is 10 minutes to 30 minutes to ensure the full mixing of alloying elements.

[0084] Vibration: Adopt vibration treatment to make the alloying elements uniformly distributed at the interface. The vibration frequency is 20 Hz to 50 Hz, and the vibration time is 10 minutes to 30 minutes to ensure the uniform distribution of alloying elements.

[0085] Electroless plating method: A technique that forms a metal coating on the surface of a substrate through a chemical reaction. It does not require an external power source but relies on a chemical reduction reaction to reduce metal ions to metal, which is deposited on the surface of the substrate. It can achieve uniform deposition of alloying elements at the interface of a copper-steel bimetallic composite material, improve the metallurgical bonding performance at the interface, reduce segregation phenomena, and thus enhance the comprehensive performance of the material.

[0086] Step S3: During the additive manufacturing process, by adjusting the cooling rate, refine the grains at the interface to reduce stress concentration caused by grain size differences.

[0087] Among them, in step S3, the following sub-steps are also included:

[0088] S3-1: During the additive manufacturing process, by controlling the temperature and flow rate of the cooling medium, adjust the cooling rate to refine the grains at the interface. The temperature of the cooling medium is controlled at 20°C to 40°C, and the flow rate is 1 L / min to 5 L / min.

[0089] S3-2: During the cooling process, use multiple-point temperature sensors to monitor the temperature change at the interface in real time, and dynamically adjust the cooling parameters according to the monitoring data to ensure a uniform and stable cooling process and avoid interface defects caused by local overcooling or overheating.

[0090] S3-3: After cooling is completed, conduct metallographic analysis on the cooled material to check the grain size and tissue uniformity at the interface. The metallographic analysis uses an optical microscope.

[0091] It should be noted that for the cooling medium: water and air are used. Water has a better cooling effect, but it may cause rapid cooling on the surface of the material, generating thermal stress; air cooling is relatively gentle, but the cooling rate is slow.

[0092] Temperature control: The temperature of the cooling medium is controlled at 20°C to 40°C. A lower temperature can accelerate the cooling rate, but it may cause overcooling on the surface of the material, generating thermal stress; a higher temperature can slow down the cooling rate, but it may cause overheating inside the material, affecting the grain refinement effect.

[0093] Flow rate control: The flow rate of the cooling medium is controlled at 1 L / min to 5 L / min. A larger flow rate can accelerate the cooling rate, but it may cause overcooling on the surface of the material; a smaller flow rate can slow down the cooling rate, but it may cause overheating inside the material.

[0094] Multiple-point temperature sensors: Arrange multiple temperature sensors at the interface to monitor the temperature change of the material in real time. Multiple-point monitoring can provide more comprehensive temperature distribution information to ensure the uniformity of the cooling process.

[0095] Dynamic adjustment: According to the monitoring data, dynamically adjust the temperature and flow rate of the cooling medium to ensure the uniformity of the cooling process. If the temperature at a certain point is too high, the cooling flow rate in this area can be appropriately increased; if the temperature at a certain point is too low, the cooling flow rate in this area can be appropriately decreased.

[0096] Optical microscope: Use an optical microscope to observe the microstructure of the material, measure the grain size and tissue uniformity. The optical microscope can provide high-resolution images for easy observation and analysis.

[0097] Grain size measurement: Use an optical microscope to measure the grain size to ensure that the grain size at the interface is uniform and small. Small grain size can improve the strength and toughness of the material and reduce stress concentration.

[0098] Tissue uniformity inspection: Inspect the tissue uniformity of the material to ensure that the cooled material has a good microstructure and reduce stress concentration caused by grain size differences.

[0099] Step S4: Perform heat treatment on the copper-steel bimetallic composite material after additive manufacturing to eliminate internal stress by controlling the heat treatment temperature and time;

[0100] Among them, in step S4, the following sub-steps are also included:

[0101] S4-1: Put the copper-steel bimetallic composite material after additive manufacturing into a heat treatment furnace and heat it to the preset heat treatment temperature at a certain heating rate. The heating rate is 10°C / min to 30°C / min, and the temperature is 500°C to 700°C;

[0102] S4-2: Keep it at the heat treatment temperature for a certain time to fully release the residual stress inside the material. The time is 1 hour to 4 hours;

[0103] S4-3: Adjust the heat treatment temperature and holding time within the adjustment range according to the performance requirements of the material and the heat treatment effect. The adjustment range is the heat treatment temperature ±50°C and the holding time ±1 hour;

[0104] S4-4: After the holding is completed, cool the material to room temperature at a certain cooling rate. The cooling rate is 10°C / min to 50°C / min.

[0105] It should be noted that the selection of the heating rate: The selection of the heating rate has an important impact on the thermal stress distribution of the material. If the heating rate is too fast, the temperature difference between the inside and outside of the material is too large, which may lead to an increase in thermal stress and even cause material deformation or cracking. Selecting a heating rate of 10°C / min to 30°C / min can avoid thermal stress caused by too large a temperature difference while ensuring the heating efficiency.

[0106] Selection of preset temperature: The temperature range of 500°C to 700°C is set based on the characteristics of the copper-steel bimetallic composite material. The recrystallization temperature of copper is about 300°C to 400°C, while that of steel is usually higher. Within this temperature range, the residual stress at the interface between copper and steel can be released through atomic diffusion and the recrystallization process, while avoiding the degradation of material properties (grain growth, hardness reduction) that may be caused by excessive temperature.

[0107] Selection of holding time: The length of the holding time determines the degree of release of the internal residual stress of the material. A longer holding time can release the residual stress more fully, but an overly long holding time may lead to instability of the material properties. Selecting a holding time of 1 hour to 4 hours can ensure the full release of stress while avoiding excessive degradation of the material properties.

[0108] Necessity of adjustment: Due to differences in the composition, structure, and additive manufacturing process of the material, different copper-steel bimetallic composite materials may require different heat treatment parameters. By adjusting the temperature and holding time, the heat treatment effect can be optimized to ensure that the material properties reach the best state.

[0109] Selection of adjustment range: The temperature adjustment range of ±50°C and the time adjustment range of ±1 hour are set based on experience and experimental data in actual production, which can cover the heat treatment requirements of most copper-steel bimetallic composite materials, while avoiding instability of the material properties caused by too large an adjustment amplitude.

[0110] Selection of cooling rate: If the cooling rate is too fast, new residual stress may be generated inside the material; if the cooling rate is too slow, the material properties may degrade (grain growth). Selecting a cooling rate of 10°C / min to 50°C / min can ensure the material properties while avoiding the generation of new residual stress.

[0111] Step S5: Perform ultrasonic impact treatment on the heat-treated copper-steel bimetallic composite material to produce compressive plastic deformation in the composite material through high-frequency impact and release the residual stress;

[0112] Among them, in step S5, the following sub-steps are also included:

[0113] S5-1: Adjust the parameters of the ultrasonic impact equipment according to the thickness and hardness of the material. The parameters include amplitude, frequency, and impact force. The amplitude is 10μm to 50μm, the frequency is 20kHz to 50kHz, and the impact force is 100N to 500N;

[0114] S5-2. According to the preset impact path and number of impacts, perform ultrasonic impact treatment on the surface of the copper-steel bimetal composite material, causing compressive plastic deformation on the material surface, eliminating the surface residual tensile stress, and forming beneficial residual compressive stress on the surface. The number of impacts is 4 to 10 times.

[0115] S5-3. During the ultrasonic impact treatment process, use strain gauges and displacement sensors to monitor the stress changes and deformation conditions on the material surface, and adjust the impact parameters in real time to ensure the uniform and effective impact treatment.

[0116] It should be noted that ultrasonic impact treatment is a process that causes compressive plastic deformation on the material surface through high-frequency impacts, thereby releasing residual stress and improving the surface properties of the material. The aim is to eliminate the residual tensile stress on the surface of the copper-steel bimetal composite material and form beneficial residual compressive stress on the surface, so as to improve the fatigue resistance and service life of the material.

[0117] The ultrasonic impact equipment includes handheld ultrasonic impact tools: amplitude: 10μm to 50μm, frequency: 20kHz to 50kHz, impact force: 100N to 500N; fixed ultrasonic impact equipment: amplitude: 20μm to 80μm, frequency: 15kHz to 40kHz, impact force: 200N to 800N; automated ultrasonic impact system: amplitude: 10μm to 60μm, frequency: 20kHz to 50kHz, impact force: 150N to 600N; portable ultrasonic impact equipment: amplitude: 10μm to 40μm, frequency: 20kHz to 40kHz, impact force: 100N to 300N.

[0118] Amplitude: The amplitude determines the size of the impact energy. A larger amplitude can provide stronger impact energy, thus more effectively eliminating residual stress. However, an excessive amplitude may cause damage to the material surface. Selecting an amplitude range of 10μm to 50μm can ensure the impact effect while avoiding damage to the material surface.

[0119] Frequency: The frequency determines the impact frequency. A higher frequency can improve the impact efficiency. However, an excessive frequency may lead to increased energy consumption of the equipment and unstable impact effect. Selecting a frequency range of 20kHz to 50kHz can improve the operation efficiency of the equipment while ensuring the impact effect.

[0120] Impact force: The impact force determines the impact strength. A larger impact force can more effectively eliminate residual stress. However, an excessive impact force may cause damage to the material surface. Selecting an impact force range of 100N to 500N can ensure the impact effect while avoiding damage to the material surface.

[0121] Influence of material thickness and hardness: The thickness and hardness of the material will affect the selection of impact parameters. Thicker or harder materials require greater impact force and amplitude, while thinner or softer materials require smaller impact force and amplitude.

[0122] Impact path: Covers the key areas on the material surface, especially the stress concentration areas, including welds and interfaces. Through reasonable impact path design, the uniformity and effectiveness of the impact treatment can be ensured.

[0123] Number of impacts: The number of impacts determines the intensity of the impact treatment. A larger number of impacts can more effectively eliminate residual stress, but too many impacts may cause fatigue damage to the material surface. Selecting 4 to 10 impacts can ensure the impact effect while avoiding fatigue damage to the material surface.

[0124] Formation of compressive plastic deformation and residual compressive stress: Ultrasonic impact treatment causes compressive plastic deformation on the material surface through high-frequency impacts, thereby eliminating the surface residual tensile stress and forming beneficial residual compressive stress on the surface. The residual compressive stress can improve the fatigue resistance and crack propagation resistance of the material.

[0125] Strain gauges and displacement sensors: Strain gauges and displacement sensors are commonly used stress monitoring devices. Strain gauges can monitor the strain changes on the material surface in real time, and displacement sensors can monitor the deformation of the material surface. Through these monitoring devices, the effect of the impact treatment can be understood in real time.

[0126] Real-time adjustment: During the impact treatment process, the stress and deformation conditions on the material surface will change continuously. By real-time monitoring and adjusting the impact parameters, the uniformity and effectiveness of the impact treatment can be ensured, and local stress being too high or too low caused by improper parameter settings can be avoided.

[0127] Adjustment method: According to the monitoring data, the amplitude, frequency, and impact force parameters can be adjusted. If the stress in a certain area is monitored to be too high, the impact force or amplitude can be appropriately reduced; if the stress in a certain area is monitored to be too low, the impact force or amplitude can be appropriately increased.

[0128] Step S6: Perform vibration treatment on the copper-steel bimetallic composite material after ultrasonic impact treatment to make the material vibrate at the resonance frequency and release stress;

[0129] Among them, in step S6, the following sub-steps are further included:

[0130] S6-1: According to the structure and size of the copper-steel bimetallic composite material, adjust the vibration frequency and amplitude of the vibration aging equipment to match the resonance frequency of the material. The vibration frequency is 10 Hz to 50 Hz, and the amplitude is 0.1 mm to 1 mm;

[0131] S6-2. Fix the material on the vibratory stress relief equipment and perform vibratory treatment on the material to make the material vibrate at the resonance frequency and release the internal residual stress.

[0132] S6-3. During the vibratory treatment, monitor the stress change and vibration response of the material in real time, and use an acceleration sensor and a strain gauge to record the vibration data to ensure the uniformity and effectiveness of the vibratory treatment.

[0133] S6-4. According to the monitoring results, dynamically adjust the vibration parameters to ensure that the material is vibrated under the optimal resonance conditions to release the internal stress to the maximum extent.

[0134] It should be noted that the resonance frequency: The resonance frequency refers to the frequency at which the vibration energy reaches the maximum value when the material vibrates at this frequency. Selecting the appropriate resonance frequency can maximize the release of the internal residual stress of the material. The structure and size of the copper-steel bimetal composite material determine that its resonance frequency range is 10 Hz to 50 Hz. If the frequency is too high or too low, it may not be able to effectively excite the resonance of the material, thereby reducing the stress release effect.

[0135] Amplitude: The amplitude determines the intensity of the vibration. A larger amplitude can provide stronger vibration energy, thereby more effectively releasing the residual stress. However, an excessive amplitude may cause surface damage or structural deformation of the material. Selecting an amplitude range of 0.1 mm to 1 mm can ensure the vibration effect while avoiding damage to the material.

[0136] Structure and size: The structure and size of the material will affect its resonance frequency and amplitude. Larger materials may require a lower vibration frequency and a larger amplitude, while smaller materials require a higher vibration frequency and a smaller amplitude.

[0137] Fixing method: The material needs to be firmly fixed on the vibratory stress relief equipment to ensure that the material does not shift or loosen during the vibration process. The fixing method can be fixture fixing or bolt fixing, and the specific selection depends on the shape and size of the material.

[0138] Vibration effect: When vibrating at the resonance frequency, the atoms and molecules inside the material will be subjected to periodic external forces, thereby promoting the release of residual stress. The vibratory treatment can effectively reduce the stress concentration inside the material and improve the stability and fatigue resistance of the material.

[0139] Acceleration sensor and strain gauge: The acceleration sensor can monitor the vibration acceleration of the material in real time, and the strain gauge can monitor the strain change on the surface of the material. Through the acceleration sensor and the strain gauge, the effect of the vibratory treatment can be understood in real time.

[0140] Real-time monitoring: During the vibration treatment process, the stress and vibration response inside the material will continuously change. Through real-time monitoring, the uniformity and effectiveness of the vibration treatment can be ensured, and local stress being too high or too low caused by improper vibration parameter settings can be avoided.

[0141] Data recording and analysis: The recorded vibration data can be processed and analyzed through professional data analysis software to evaluate the effect of the vibration treatment. By analyzing the acceleration and strain data, the stress distribution inside the material can be determined, thereby judging whether the vibration treatment has achieved the expected effect.

[0142] Adjustment method: According to the monitoring data, the vibration frequency, amplitude, and vibration time parameters can be adjusted. If the stress in a certain area is detected to be too high, the amplitude can be increased or the vibration time can be extended; if the stress in a certain area is detected to be too low, the amplitude can be decreased or the vibration time can be shortened.

[0143] Dynamic adjustment: During the vibration treatment process of the material, its internal structure and stress state will continuously change. Therefore, the vibration parameters need to be dynamically adjusted according to the real-time monitoring data to ensure the effect of the vibration treatment. Dynamic adjustment can avoid local stress being too high or too low caused by improper parameter settings, thereby improving the uniformity and effectiveness of the vibration treatment.

[0144] Adjustment range: The adjustment range of the vibration frequency is ±5 Hz, and the adjustment range of the amplitude is usually ±0.1 mm. The adjustment range is set based on the experience and experimental data in actual production and can cover the vibration treatment requirements of most copper-steel bimetallic composite materials.

[0145] Step S7: Detect the distribution of internal stress through ultrasonic testing technology to ensure that the internal stress of the copper-steel bimetallic composite material is effectively eliminated;

[0146] Among them, in step S7, the following sub-steps are also included:

[0147] S7-1: Adopt ultrasonic testing technology, set the detection parameters, and perform internal stress detection on the processed copper-steel bimetallic composite material. The detection parameters include frequency, pulse width, gain, probe angle, and coupling medium;

[0148] S7-2: During the detection process, record the stress distribution of the material, analyze the data using ultrasonic signal analysis software, evaluate the stress elimination effect, and determine whether the internal stress of the material is within the controllable range;

[0149] S7-3: If the detection result shows that the internal stress exceeds the controllable range, repeat steps S4 - S6 to further optimize and adjust the production preparation process until the internal stress is effectively eliminated and the material performance is stable and reliable.

[0150] It should be noted that for frequency: the higher the frequency, the higher the resolution of the ultrasonic wave, but the weaker the penetration ability; the lower the frequency, the stronger the penetration ability, but the lower the resolution. The frequency of the ultrasonic wave is between 1 MHz and 10 MHz, which can ensure sufficient penetration depth while guaranteeing the detection accuracy. The specific frequency selection depends on the thickness of the material and the detection depth. High-frequency ultrasonic waves (5 MHz to 10 MHz) are suitable for thin plates or surface detection, while low-frequency ultrasonic waves (1 MHz to 3 MHz) are suitable for thick plates or internal detection.

[0151] Pulse width: The pulse width affects the penetration ability and resolution of the ultrasonic wave. A short pulse width (10 ns to 50 ns) provides higher resolution but weaker penetration ability; a long pulse width (100 ns to 500 ns) provides stronger penetration ability but lower resolution.

[0152] Gain: Gain is used to adjust the intensity of the ultrasonic signal to ensure that the signal will not be lost due to attenuation during the detection process. A higher gain can improve the sensitivity of the signal, but it may introduce noise; a lower gain can reduce noise, but it may reduce the sensitivity of the signal. It is usually between 20 dB and 60 dB, and the specific value is adjusted according to the attenuation characteristics of the material.

[0153] Probe angle: The probe angle affects the incident direction and reflection characteristics of the ultrasonic wave, determining the propagation direction of the ultrasonic wave in the material. Selecting a probe angle of 45° to 70° can improve the detection accuracy while ensuring the detection coverage.

[0154] Coupling medium: The coupling medium is used to reduce the air gap between the probe and the material surface, improving the transmission efficiency of the ultrasonic wave between the probe and the material surface. It includes water, glycerin, machine oil, and coupling agent. Selecting a suitable coupling medium can reduce signal attenuation and reflection, improving the detection effect.

[0155] Recording of stress distribution: Record the stress distribution inside the material through an ultrasonic detection device. The propagation speed and reflection characteristics of the ultrasonic wave in the material will change due to different stress states. Therefore, the stress distribution can be evaluated by detecting these changes.

[0156] Data analysis: Use ultrasonic signal analysis software to process and analyze the recorded data. The analysis software can extract the stress distribution characteristics through signal processing algorithms (Fourier transform) and generate a stress distribution map.

[0157] Evaluation criteria: Set the evaluation criteria for stress elimination according to the performance requirements and application background of the material. The internal stress should be lower than a certain percentage (10% to 20%) of the yield strength of the material to ensure the stability and reliability of the material during use.

[0158] Controllable range: If the test result shows that the internal stress is within the controllable range, it indicates that the stress relief effect is good; if the internal stress exceeds the controllable range, further optimization of the processing technology is required.

[0159] Repeating steps: If the internal stress exceeds the controllable range, heat treatment (step S4), ultrasonic impact treatment (step S5), and vibration treatment (step S6) need to be carried out again, and relevant process parameters are adjusted according to the test results.

[0160] Optimization and adjustment: According to the ultrasonic test results, analyze the uneven stress distribution areas or areas with excessive stress, and adjust the heat treatment temperature and time, ultrasonic impact parameters (amplitude, frequency, impact force, number of impacts), and vibration treatment parameters (vibration frequency, amplitude, vibration time) accordingly.

[0161] Iterative optimization: Through multiple iterative optimizations, gradually adjust the process parameters until the internal stress is effectively eliminated and the material properties are stable and reliable. After each optimization, ultrasonic testing needs to be carried out again to ensure the optimization effect.

[0162] In this way, a production preparation method for eliminating the internal stress of copper-steel bimetallic composites can effectively eliminate the internal stress of copper-steel bimetallic composites, optimize the interface microstructure at the same time, improve the overall performance of the material, and ensure its stability and reliability in practical applications.

[0163] The above-described embodiments are only used to illustrate the technical solutions of the present application, and are not intended to limit them; although the present application has been described in detail with reference to the foregoing embodiments, those of ordinary skill in the art should understand that they can still modify the technical solutions recorded in the foregoing embodiments, or perform equivalent replacements on some of the technical features; and these modifications or replacements do not make the essence of the corresponding technical solutions deviate from the spirit and scope of the technical solutions of the embodiments of the present application, and should all be included in the protection scope of the present application.

Claims

1. A production method capable of eliminating internal stress of a copper-steel bimetallic composite material, characterized in that: The method includes: Step S1, preparing a copper-steel bimetallic composite material by using additive manufacturing technology, and controlling the heat source parameters and scanning path to achieve regulation of the interface structure; Step S2, adding alloy elements at the copper-steel interface to promote diffusion and uniform distribution of the elements and reduce segregation at the interface; Step S3, during the additive manufacturing process, by adjusting the cooling rate, the grains at the interface are refined to reduce the stress concentration caused by the grain size difference; Step S4, heat treating the copper-steel bimetallic composite material after additive manufacturing, and eliminating internal stress by controlling the heat treatment temperature and time; Step S5, performing ultrasonic impact treatment on the copper-steel bimetallic composite material after the heat treatment, so as to cause compressive plastic deformation of the composite material by high-frequency impact and release residual stress; Step S6, vibrating the copper-steel bimetallic composite material after the ultrasonic impact treatment to make the material vibrate at a resonant frequency to release stress; Step S7, detecting the distribution of internal stress by ultrasonic detection technology to ensure that the internal stress of the copper-steel bimetallic composite material is effectively eliminated; Wherein step S2 also includes the following sub-steps: S2-1, adding an appropriate amount of alloying elements at the copper-steel interface, which can form a solid solution or intermetallic compound with copper and steel to promote the diffusion and uniform distribution of the elements, and the alloying elements include nickel, chromium, molybdenum, iron, manganese and silicon; S2-2, by optimizing the addition amount of alloying elements, controlling the chemical composition gradient at the interface, and reducing the interface segregation phenomenon caused by composition differences, the addition amount is 0.5% to 5% of the total weight at the copper-steel interface; S2-3, using stirring, vibration and chemical plating to evenly distribute the alloy elements at the interface, the stirring time is 10 minutes to 30 minutes, and the rated frequency of the vibration is 20 Hz to 50 Hz; Wherein step S4 also includes the following sub-steps: S4-1, placing the copper-steel bimetallic composite material after additive manufacturing into a heat treatment furnace, and heating it to a preset heat treatment temperature at a certain heating rate, wherein the heating rate is 10°C / min to 30°C / min, and the temperature is 500°C to 700°C; S4-2, maintaining the material at the heat treatment temperature for a certain period of time to fully release the residual stress inside the material, wherein the period of time is 1 hour to 4 hours; S4-3, according to the performance requirements of the material and the heat treatment effect, the heat treatment temperature and the heat preservation time are adjusted within the adjustment range, and the adjustment range is the heat treatment temperature ± 50 ° C, and the heat preservation time ± 1 hour; S4-4, after the heat preservation is completed, cooling the material to room temperature at a certain cooling rate, wherein the cooling rate is 10°C / min to 50°C / min; Wherein, in step S5, the following sub-steps are also included: S5-1, adjusting the parameters of the ultrasonic impact equipment according to the thickness and hardness of the material, the parameters including amplitude, frequency, and impact force, the amplitude being 10 μm to 50 μm, the frequency being 20 kHz to 50 kHz, and the impact force being 100 N to 500 N; S5-2, performing ultrasonic impact treatment on the surface of the copper-steel bimetallic composite material according to a preset impact path and impact times, so as to cause compressive plastic deformation on the surface of the material, eliminate the surface residual tensile stress, and form beneficial residual compressive stress on the surface, wherein the impact times are 4 to 10 times; S5-3, during the ultrasonic impact treatment process, strain gauges and displacement sensors are used to monitor the stress changes and deformation of the material surface, and the impact parameters are adjusted in real time to ensure that the impact treatment is uniform and effective; Wherein, in step S6, the following sub-steps are also included: S6-1, according to the structure and size of the copper-steel bimetallic composite material, adjust the vibration frequency and amplitude of the vibration aging equipment to match the resonant frequency of the material, the vibration frequency is 10Hz to 50Hz, and the amplitude is 0.1mm to 1mm; S6-2, fix the material on the vibration aging equipment, perform vibration treatment on the material, make the material vibrate at the resonance frequency, and release the internal residual stress; S6-3, during the vibration treatment process, real-time monitoring of material stress changes and vibration response, using accelerometers and strain gauges to record vibration data to ensure the uniformity and effectiveness of the vibration treatment; S6-4, dynamically adjust the vibration parameters according to the monitoring results to ensure that the material is vibrated under the best resonance conditions to release the internal stress to the maximum extent.

2. A production method capable of eliminating internal stress of a copper-steel bimetallic composite material as claimed in claim 1, characterized in that: Wherein step S1 also includes the following sub-steps: S1-1, selecting additive manufacturing technology according to the application needs and performance requirements of the copper-steel bimetallic composite material, wherein the additive manufacturing technology includes laser additive manufacturing, electron beam additive manufacturing, and arc additive manufacturing; S1-2, designing scanning path and heat source parameters to achieve regulation of interface structure, wherein the heat source parameters include laser power, scanning speed, electron beam energy, and arc current; S1-3, real-time monitoring of the molding state and interface quality of the material, using laser displacement sensors and thermal imagers to detect the molten pool temperature, molten pool size and interlayer bonding of the material, and adjusting the heat source parameters.

3. A production method capable of eliminating internal stress of a copper-steel bimetallic composite material as claimed in claim 1, characterized in that: Wherein step S3 also includes the following sub-steps: S3-1, in the additive manufacturing process, the cooling rate is adjusted by controlling the temperature and flow rate of the cooling medium to refine the grains at the interface, wherein the temperature of the cooling medium is controlled at 20° C. to 40° C. and the flow rate is 1 L / min to 5 L / min; S3-2, during the cooling process, use multi-point temperature sensors to monitor the temperature changes at the interface in real time, and dynamically adjust the cooling parameters according to the monitoring data to ensure that the cooling process is uniform and stable, and avoid interface defects caused by local overcooling or overheating; S3-3, after cooling is completed, metallographic analysis is performed on the cooled material to check the grain size and structural uniformity at the interface, and the metallographic analysis is performed using an optical microscope.

4. A production method capable of eliminating internal stress of a copper-steel bimetallic composite material as claimed in claim 1, characterized in that: Wherein, in step S7, the following sub-steps are also included: S7-1, using ultrasonic testing technology, setting testing parameters, and performing internal stress testing on the treated copper-steel bimetallic composite material, wherein the testing parameters include frequency, pulse width, gain, probe angle, and coupling medium; S7-2, during the testing process, record the stress distribution of the material, use ultrasonic signal analysis software to analyze the data, evaluate the stress relief effect, and determine whether the internal stress of the material is within the controllable range; S7-3, if the test results show that the internal stress exceeds the controllable range, repeat steps S4-S6 to further optimize and adjust the production process until the internal stress is effectively eliminated and the material performance is stable and reliable.

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