Device and method for forming aluminum alloy cladding layer through synchronous laser cladding and composite ultrasonic impact

Abstract

The invention relates to the technical field of laser cladding, and provides a device and method for forming an aluminum alloy cladding layer through synchronous laser cladding and composite ultrasonic peening, and the device comprises a laser cladding head and an ultrasonic peening needle; the ultrasonic peening needle comprises a shaft body; a ceramic coating is arranged on the outer surface of the shaft body; the laser cladding head and the ultrasonic peening needle are located on the same side of a to-be-repaired base body, and the ultrasonic peening needle synchronously follows the laser cladding head, so that the laser cladding head conducts laser cladding on the to-be-repaired base body to form a molten pool, and meanwhile the to-be-repaired base body is subjected to ultrasonic peening. The end face of the ultrasonic peening needle generates peening pressure perpendicular to the to-be-repaired base body on the to-be-repaired base body. According to the method, in the process of forming the aluminum alloy through laser cladding, under the condition of good plasticity, the ultrasonic impact needle with the ceramic coating is adopted, the composite ultrasonic impact mechanical auxiliary field is synchronously followed, and the aluminum alloy laser cladding layer which is nearly free of defects, refined in grain and improved in performance is obtained.

Description

Technical Field

[0001] This invention relates to the field of laser cladding technology, and in particular to an apparatus and method for laser cladding and simultaneous composite ultrasonic impact forming of aluminum alloy cladding layers. Background Technology

[0002] Aluminum alloys offer significant advantages: lightweight yet high strength, excellent corrosion resistance, ease of processing, and recyclability, leading to their widespread application in rail transportation, aerospace, and the automotive industry. However, during use, aluminum alloy components often suffer from material performance degradation and structural integrity impairment due to a combination of factors, including corrosion, wear, fatigue, stress corrosion cracking, high-temperature oxidation, and fretting damage. This ultimately affects the service life of the components and the reliability of the equipment. Currently, laser cladding technology, characterized by concentrated energy, controllable heat input, strong material compatibility, and a high degree of automation, can restore the shape, size, and performance of damaged aluminum alloy components, enabling their repair and remanufacturing.

[0003] However, during the laser cladding process of aluminum alloys, the solubility of gases (mainly hydrogen) decreases rapidly during the solidification and cooling of the liquid aluminum alloy, resulting in porosity due to insufficient time for precipitation. Furthermore, the rapid heating and cooling of laser cladding easily causes residual tensile stress, severely affecting the fatigue life of laser-clad repaired aluminum alloy parts. Based on laser cladding technology, combining it with the inherent advantages of ultrasonic impact mechanical auxiliary fields can overcome the limitations of single laser additive manufacturing and solve the persistent problem of porosity defects in aluminum alloy laser cladding. However, the current composite process achieves metallurgical bonding of the material surface through laser cladding in a cold state, while simultaneously using high-frequency mechanical impact from ultrasonic shock to improve the porosity defects and stress state of the laser-clad layer. However, it cannot solve the problem of microstructural degradation in the heat-affected zone of the substrate caused by heat input during laser cladding, making it difficult to improve the microhardness of laser-clad repaired aluminum alloy parts. Summary of the Invention

[0004] The ultrasonic impact pin is the core component of the ultrasonic impact equipment. The impact pin generally acts directly on the surface of the workpiece. This invention provides a device and method for forming an aluminum alloy cladding layer by synchronous composite ultrasonic impact during laser cladding. By optimizing the structure of the ultrasonic impact pin and adjusting the ultrasonic impact pin to synchronously follow the laser cladding head to directly apply the action to the incompletely cooled cladding layer, this invention solves the problems of microstructure deterioration in the heat-affected zone of the substrate caused by heat input during the laser cladding process in the prior art, and the difficulty in improving the microhardness and mechanical properties of aluminum alloy parts repaired by laser cladding.

[0005] This invention provides an ultrasonic-assisted laser cladding device, comprising: a laser cladding head and an ultrasonic impact needle; the ultrasonic impact needle includes a shaft; the outer surface of the shaft is provided with a ceramic coating; The laser cladding head and the ultrasonic impact needle are located on the same side of the substrate to be repaired. The ultrasonic impact needle synchronously follows the laser cladding head, so that while the laser cladding head performs laser cladding on the substrate to be repaired to form a molten pool, the end face of the ultrasonic impact needle generates an impact pressure perpendicular to the substrate to be repaired.

[0006] The laser cladding head is used to provide a laser beam.

[0007] Preferably, the end face is in direct contact with the substrate to be repaired, so that the ultrasonic impact needle is perpendicular to the substrate to be repaired, thereby generating the impact pressure.

[0008] The ultrasonic impact pin synchronously follows the laser cladding head. This can be achieved by using independent robotic arms to control both the ultrasonic impact pin and the laser cladding head, or by using the same robotic arm to control both simultaneously. The ceramic coating in this invention possesses high heat resistance and laser reflection resistance. Therefore, when the ultrasonic impact pin synchronously follows the laser cladding head, it allows for extremely close-field coupling between the heat source and the impact source, with the pin tip extremely close to the surface of the liquid metal in the molten pool. This enables the application of high-frequency ultrasonic impact loads while the laser cladding layer still has a high temperature, completing deformation while the cladding layer has good plasticity. This closes pore defects, regulates residual stress, and improves the softening problem in the heat-affected zone.

[0009] The ultrasonic impact needle of this invention has a connection method and operation method that is basically the same as that of the ultrasonic impact needle used in the prior art in ultrasonic impact equipment. For example, it can be fixed to the impact head by mechanical locking (such as threaded connection) or elastic clamping (such as spring clip) to ensure vibration transmission efficiency. However, the outer surface of the shaft of the ultrasonic impact needle in this invention is provided with a ceramic coating. In order to adapt to the existing coating process and to ensure that the ultrasonic impact needle can move up and down in the needle sleeve, the ultrasonic impact needle of this invention is structurally optimized. Specifically, according to the ultrasonic assisted laser cladding device provided by this invention, the shaft is a columnar structure, and a first section, a second section and a third section are provided in sequence along its axial direction. The cross-sectional area of ​​each section is different, and the cross-sectional area of ​​the second section is smaller than that of the first section. The first segment is one end of the shaft, and its end face is a closed planar structure; The first segment and the second segment are coaxially connected, forming a stepped surface I at the connection between the two segments; The second segment is coaxially connected to the third segment, forming a stepped surface II at the junction of the two segments; The outer peripheral surface of the second segment, the surface of step surface I, and the surface of step surface II are provided with a ceramic coating.

[0010] As an example, when the ultrasonic impact device is fixed to the impact head by elastic clamping, the spring at the upper end of the impact pin is compressed and deformed by pressing down the robotic arm. The amount of spring compression is adjusted by the pressing height of the robotic arm to change the pressure of the impact head on the workpiece surface.

[0011] Specifically, during laser cladding, the surface of the ultrasonic impact pin is prone to heat accumulation (temperatures can reach several hundred degrees Celsius) due to repeated energy inputs. The ceramic coating in this invention reflects over 70% of thermal radiation energy, reducing the surface temperature by 30% to 40%, thus preventing a decrease in the dimensional accuracy of the impact pin due to thermal softening. Materials suitable for the ceramic coating of this invention include, but are not limited to, oxide ceramics, nitride ceramics, and carbide ceramics.

[0012] Preferably, in the ultrasonic-assisted laser cladding device provided by the present invention, the thickness of the ceramic coating is less than 1 mm, for example, it can be any value or a numerical range composed of any values ​​among 0.1 mm, 0.2 mm, 0.3 mm, 0.4 mm, 0.5 mm, 0.6 mm, 0.7 mm, 0.8 mm, 0.9 mm, and 1 mm, preferably 0.5 to 1 mm.

[0013] To improve the durability of the ultrasonic impact needle, preferably, the height of the first segment is less than 0.8 mm, and more preferably 0.5 to 0.8 mm.

[0014] Preferably, the total height of the first segment, the second segment, the step surface I, and the step surface is 10 mm or more, and more preferably 15 mm or more.

[0015] Preferably, the columnar structure is a cylindrical structure.

[0016] Preferably, the stepped surface I forms an angle of less than 90 degrees with the axis of the shaft.

[0017] Preferably, the stepped surface II forms an angle of less than 90 degrees with the axis of the shaft.

[0018] Preferably, the equivalent diameter of the cross-section of the third segment is 6~9mm; Preferably, the total height of the shaft is 25~36mm.

[0019] Preferably, the ceramic coating is formed using a thermal spraying process.

[0020] Since the laser cladding head and the ultrasonic impact needle are located on the same side of the substrate to be repaired, and the ultrasonic impact needle synchronously follows the laser cladding head, the smaller the minimum distance between the axis of the ultrasonic impact needle and the molten pool, the higher the temperature of the cladding area when the impact pressure acts on it. However, if the minimum distance between the axis of the ultrasonic impact needle and the molten pool is too close, it is not conducive to improving the overall performance of the cladding area. Preferably, in the ultrasonic-assisted laser cladding device provided by the present invention, the minimum distance between the axis of the ultrasonic impact needle and the molten pool is 5~15mm. For example, it can be any value or a range of values ​​from 5mm, 6mm, 7mm, 8mm, 9mm, 10mm, 11mm, 12mm, 13mm, 14mm, and 15mm.

[0021] According to the ultrasonic-assisted laser cladding device provided by the present invention, the laser cladding head includes a coaxial powder feeding nozzle.

[0022] Preferably, the direction of the laser beam generated by the laser cladding head is at an angle of 20° to 40° with the axis of the ultrasonic impact needle to avoid interference. For example, it can be any value or a range of values ​​among 20°, 25°, 30°, 35°, and 40°.

[0023] Generally, to make the laser cladding head more functional, it may also include components such as a laser emitter, a laser collimating lens group, a powder supply device (such as a powder feeder), a cooling system (such as a water-cooled jacket or an air-cooled device), and a guiding device (such as a multi-axis displacement stage or a robot arm mounting structure).

[0024] Similarly, to facilitate the installation of ultrasonic impact needles, the ultrasonic impact needles may include components such as ultrasonic transducers (e.g., piezoelectric ceramic actuators), energy amplifiers, needle holders and needle replacement mechanisms, and vibration buffer components (shock-absorbing devices to reduce noise and losses during device operation).

[0025] For the aforementioned ultrasonic-assisted laser cladding device, to achieve control sensitivity and accuracy while ensuring ease of operation, a collaborative control system and a positioning and monitoring system can be set up. The collaborative control system generally includes a main control unit (control components, including a PLC or industrial control computer), a synchronization control module (for coordinating the timing and parameters of laser cladding and ultrasonic impact), and a human-machine interface (for parameter setting, monitoring, and fault diagnosis). The positioning and monitoring system generally includes a workpiece positioning device (such as a fixture, rotary table, etc.), a cladding layer temperature monitoring sensor, an ultrasonic intensity detection device, and a laser output power detection unit.

[0026] The present invention also provides a method for laser cladding and simultaneous ultrasonic impact forming of aluminum alloy cladding layer, comprising: using aluminum alloy powder as raw material, and forming an aluminum alloy cladding layer on the aluminum alloy substrate to be repaired using the ultrasonic-assisted laser cladding device described above.

[0027] According to the method provided by the present invention, the laser beam parameters include: The restoration atmosphere is the atmospheric environment; The energy distribution is a Gaussian beam; The spot diameter is 1~1.5mm; for example, it can be any value or a range of values ​​from 1.0mm, 1.1mm, 1.2mm, 1.3mm, 1.4mm, 1.5mm.

[0028] The laser power is 1600~1800W; for example, it can be any value or a range of values ​​among 1600W, 1650W, 1700W, 1750W, and 1800W.

[0029] The scanning speed is 300~900 mm / min; for example, it can be any value or a range of values ​​among 300 mm / min, 400 mm / min, 500 mm / min, 600 mm / min, 700 mm / min, 800 mm / min, and 900 mm / min.

[0030] The powder feeding rate is 1.0~2.5 g / min; for example, it can be any value or a range of values ​​from 1.0 g / min, 1.1 g / min, 1.2 g / min, 1.3 g / min, 1.4 g / min, 1.5 g / min, 1.6 g / min, 1.7 g / min, 1.8 g / min, 1.9 g / min, 2.0 g / min, 2.1 g / min, 2.2 g / min, 2.3 g / min, 2.4 g / min, and 2.5 g / min.

[0031] The overlap rate is 40-50%. For example, it can be any value or a range of values ​​from 40%, 41%, 42%, 43%, 44%, 45%, 46%, 47%, 48%, 49%, and 50%.

[0032] By controlling the laser beam parameters within the above range, problems such as poor fusion, spheroidization, or a large number of visible pores caused by improper parameter settings can be avoided, which in turn affect the mechanical properties after repair.

[0033] According to the method provided by the present invention, the impact pressure is 50~200N; for example, it can be any value or a range of values ​​composed of 50N, 70N, 90N, 110N, 130N, 150N, 170N, 190N, and 200N.

[0034] Preferably, the frequency of the ultrasonic impact gun is 18~20KHz, for example, it can be any value or a range of values ​​composed of 18KHz, 19KHz, and 20KHz.

[0035] The power of the ultrasonic impact gun is 600~1000W, for example, it can be any value or a range of values ​​among 600W, 650W, 700W, 750W, 800W, 850W, 900W, 950W, and 1000W.

[0036] The amplitude of the ultrasonic impact gun is 35~40 μm; for example, it can be any value or a range of values ​​among 35μm, 36μm, 37μm, 38μm, 39μm, and 40μm.

[0037] The moving speed of the ultrasonic impact gun is consistent with the scanning speed of the laser beam.

[0038] Within the above parameter range, the ultrasonic impact gun can be used continuously for a long time.

[0039] According to the method provided by the present invention, the aluminum alloy powders applicable to the present invention include, but are not limited to, AlSi10Mg and AlMgScZr, and other aluminum alloy powder materials that can be used for laser cladding repair are also applicable.

[0040] Preferably, the material of the aluminum alloy substrate to be repaired is cast aluminum alloy, various heat-treatable and non-heat-treatable deformable aluminum alloys, including but not limited to aluminum alloys such as ZL101, 5083 and 7N01.

[0041] The present invention also provides an aluminum alloy part, the aluminum alloy part including an aluminum alloy cladding layer, the aluminum alloy cladding layer being formed by the method described above.

[0042] The apparatus and method for laser cladding and synchronous composite ultrasonic impact forming of aluminum alloy cladding layers provided by the present invention, in the process of laser cladding forming of aluminum alloy, under the condition that the aluminum alloy has a high temperature and good plasticity, an ultrasonic impact needle with ceramic coating that is resistant to high heat and laser reflection is used to synchronously follow the composite ultrasonic impact mechanical auxiliary field to obtain a near-defect-free aluminum alloy laser cladding layer with refined grains, improved performance, and residual compressive stress, effectively improving the softening problem of the heat-affected zone of aluminum alloy laser cladding. Attached Figure Description

[0043] To more clearly illustrate the technical solutions in this invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are some embodiments of this invention. For those skilled in the art, other drawings can be obtained from these drawings without creative effort.

[0044] Figure 1 This is a schematic diagram of the ultrasonic impact needle provided by the present invention.

[0045] Figure 2 This is a schematic diagram of the process of laser cladding synchronous composite ultrasonic impact forming of aluminum alloy cladding layer provided by the present invention.

[0046] Figure 3 This is a photograph of the burnt-out conventional unmodified flat needle provided in Comparative Example 2 of this invention.

[0047] Figure 4 This is a metallographic diagram of Embodiment 2 provided by the present invention.

[0048] Figure 5 These are hardness variation trend diagrams for Examples 2, 4-5 provided by the present invention.

[0049] Figure 6 This is a metallographic diagram of Comparative Example 1 provided by the present invention.

[0050] Figure 7 This is a graph showing the hardness variation trend of Comparative Example 1 and Examples 6-8 provided by the present invention.

[0051] Figure 8 This is the metallographic structure diagram of Comparative Example 3 provided by the present invention. Detailed Implementation

[0052] To make the objectives, technical solutions, and advantages of this invention clearer, the technical solutions of this invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some, not all, of the embodiments of this invention. All other embodiments obtained by those skilled in the art based on the embodiments of this invention without creative effort are within the scope of protection of this invention.

[0053] Where specific techniques or conditions are not specified in the examples, they shall be performed in accordance with the techniques or conditions described in the literature in this field, or in accordance with the product instructions. Reagents or instruments whose manufacturers are not specified are all conventional products that can be purchased through legitimate channels.

[0054] The repair material used in the following examples is AlMgScZr high-strength aluminum alloy powder, and the repair substrate is 7N01 heat-treatable aluminum alloy. Before cladding, the oil and oxide film on the surface of the repair substrate are quickly cleaned by surface cleaning methods such as laser cleaning / acid and alkali washing.

[0055] Example 1: Ultrasonic-assisted laser cladding device An ultrasonic-assisted laser cladding device, such as Figure 1 As shown, it includes: a laser cladding head, an ultrasonic impact needle, a collaborative control system, and a positioning and monitoring system; The ultrasonic impact needle includes a shaft; the shaft is a cylindrical structure with a total height of 36mm, and has three sections arranged sequentially along its axis, each with a different cross-sectional area. The first section is one end of the shaft, and its end face is a closed planar structure; the height of the first section is 0.5mm, and its cross-sectional diameter is 8mm. The first and second sections are coaxially connected, forming a stepped surface I at the junction; stepped surface I forms a 45-degree angle with the shaft axis. The second and third sections are coaxially connected, forming a stepped surface II at the junction; stepped surface II forms a 15-degree angle with the shaft axis. The diameter of the cross-section of the third section is 8mm. The total length of the first, second, stepped surfaces I and II along the shaft axis is 15mm. The outer circumference of the second section, the surface of stepped surface I, and the surface of stepped surface II are coated with a 0.5mm thick ceramic coating formed by thermal spraying. The third section of the shaft is elastically clamped and fixed to the impact head for guidance and pressure application.

[0056] The laser cladding head and the ultrasonic impact needle are located on the same side of the substrate to be repaired.

[0057] The laser cladding head includes a laser emitter, a powder feeder, a coaxial powder feeding nozzle, a water-cooling jacket, and a guiding device, which are used to provide the laser beam.

[0058] The collaborative control system includes a main control unit with a PLC, a synchronous control module for coordinating the timing and parameters of laser cladding and ultrasonic impact, and a human-machine interface for parameter setting and monitoring.

[0059] The positioning and monitoring system includes a workpiece positioning device, a cladding layer temperature monitoring sensor, an ultrasonic strength testing device, and a laser output power testing unit.

[0060] Example 2 A method for laser cladding and simultaneous ultrasonic impact forming of aluminum alloy cladding layers, such as... Figure 2 As shown, the process includes: using aluminum alloy powder as the repair material, and drying the repair material in a drying oven at 120°C for 2 hours. An aluminum alloy cladding layer is formed on the aluminum alloy substrate to be repaired using the ultrasonic-assisted laser cladding device described in Example 1.

[0061] In this process, the ultrasonic impact needle synchronously follows the laser cladding head, so that while the laser cladding head performs laser cladding on the substrate to be repaired to form a molten pool, the end face of the ultrasonic impact needle generates an impact pressure perpendicular to the substrate to be repaired.

[0062] The laser beam parameters include: the repair atmosphere is atmospheric; the energy distribution is a Gaussian beam; the spot diameter is 1.5 mm; the laser power is 1800 W; the scanning speed is 600 mm / min; the powder feeding rate is 1.5 g / min; and the overlap rate is 50%.

[0063] The ultrasonic impact gun has a frequency of 18 kHz, a power of 800 W, and an amplitude of 35 μm; the moving speed of the ultrasonic impact gun is consistent with the scanning speed of the laser beam; the impact pressure generated by the ultrasonic impact gun is 50 N.

[0064] The laser beam generated by the laser cladding head is set to form an angle of 35° with the axis of the ultrasonic impact needle, and the minimum distance between the axis of the ultrasonic impact needle and the molten pool is kept at 5mm.

[0065] Example 3 A method for laser cladding and simultaneous ultrasonic impact forming of an aluminum alloy cladding layer includes: using aluminum alloy powder as the repair material, and drying the repair material in a drying oven at 130℃ for 2 hours. The ultrasonic-assisted laser cladding device of Example 1 is used to form the aluminum alloy cladding layer on the aluminum alloy substrate to be repaired.

[0066] In this process, the ultrasonic impact needle synchronously follows the laser cladding head, so that while the laser cladding head performs laser cladding on the substrate to be repaired to form a molten pool, the end face of the ultrasonic impact needle generates an impact pressure perpendicular to the substrate to be repaired.

[0067] The laser beam parameters include: the repair atmosphere is atmospheric; the energy distribution is a Gaussian beam; the spot diameter is 1.5 mm; the laser power is 1600 W; the scanning speed is 480 mm / min; the powder feeding rate is 1.0 g / min; and the overlap rate is 50%.

[0068] The ultrasonic impact gun has a frequency of 18 kHz, a power of 800 W, and an amplitude of 35 μm; the moving speed of the ultrasonic impact gun is consistent with the scanning speed of the laser beam; the impact pressure generated by the ultrasonic impact gun is 100 N.

[0069] The laser beam generated by the laser cladding head is set to form an angle of 30º with the axis of the ultrasonic impact needle, and the minimum distance between the axis of the ultrasonic impact needle and the molten pool is kept at 10mm.

[0070] Examples 4-5 This is basically the same as Example 2, except that the minimum distance between the axis of the ultrasonic impact pin and the molten pool is adjusted, as shown in the table below: Table 1

[0071] Examples 6-8 This is basically the same as Example 2, except that the impact pressure generated by the ultrasonic impact gun is adjusted, as shown in the table below: Table 2

[0072] Comparative Example 1 The process is basically the same as in Example 2, except that the ultrasonic impact needle is not activated, and the direction of the laser beam generated by the laser cladding head is set to be perpendicular to the substrate to be repaired, so as to form an aluminum alloy cladding layer on the aluminum alloy substrate to be repaired.

[0073] Comparative Example 2 The results were largely the same as in Example 3, except that the ultrasonic impact needle in the ultrasonic-assisted laser cladding device was replaced with a traditional unmodified flat needle. The results showed that the traditional unmodified flat needle was severely burned during operation, such as... Figure 3 As shown.

[0074] Comparative Example 3 A method for laser cladding simultaneously with ultrasonic impact forming of an aluminum alloy cladding layer includes: using aluminum alloy powder as the repair material, and drying the repair material in a drying oven at 125°C for 2 hours. Another ultrasonic-assisted laser cladding device is used, differing from the ultrasonic-assisted laser cladding device in Example 1 only in that the ultrasonic impact needle is replaced with a traditional unmodified flat needle, to form an aluminum alloy cladding layer on the aluminum alloy substrate to be repaired.

[0075] The steps for forming an aluminum alloy cladding layer are as follows: First, the laser cladding head is activated to perform laser cladding on the substrate to be repaired and then cooled to form a cladding layer; then, the traditional unmodified flat needle is activated, and the end face of the traditional unmodified flat needle generates an impact pressure perpendicular to the substrate to be repaired.

[0076] The laser beam parameters include: the repair atmosphere is atmospheric; the energy distribution is a Gaussian beam; the spot diameter is 1.5 mm; the laser power is 1800 W; the scanning speed is 600 mm / min; the powder feeding rate is 1.5 g / min; and the overlap rate is 50%.

[0077] The traditional unmodified flat needle has a frequency of 18KHz, a power of 800W, and an amplitude of 35μm; the traditional unmodified flat needle moves at a speed of 480 mm / min; and the ultrasonic impact gun generates an impact pressure of 100N.

[0078] The laser beam generated by the laser cladding head is set to form an angle of 35º with the axis of the ultrasonic impact needle, and the minimum distance between the axis of the ultrasonic impact needle and the cladding layer is kept at 10mm.

[0079] Test Example 1 (1) Microstructure (2) Hardness change trend curve: Microhardness tests were performed on different areas of the obtained coating.

[0080] The test results are as follows: The metallographic structure and hardness variation trend diagram of Example 2 are as follows: Figures 4-5 As shown.

[0081] The hardness variation trend graphs of Examples 2, 4, and 5 are shown below. Figure 5 As shown.

[0082] The metallographic structure and hardness variation trend diagram of Comparative Example 1 are as follows: Figures 6-7 As shown.

[0083] The hardness variation trend graphs of Comparative Example 1, Example 2, and Examples 6-8 are shown below. Figure 7 As shown.

[0084] Figure 8 This is the metallographic structure diagram of Comparative Example 3 provided by the present invention.

[0085] The test results above show that: from Figure 5 It can be seen that the closer to the molten pool, the more significant the increase in microhardness of the boundary heat-affected zone caused by ultrasonic impact, that is, the smaller the degree of softening caused by the heat effect of laser cladding, and the effect on the cladding zone is basically the same.

[0086] from Figure 7 It can be seen that the increase in microhardness in the cladding zone and the boundary heat-affected zone gradually increases with increasing impact pressure. The increase in hardness in the cladding zone with increasing impact pressure is due to the greater the impact force, the greater the work hardening in the cladding zone, resulting in higher hardness in this area. Similarly, the increase in hardness in the boundary heat-affected zone is due to the increased impact pressure, which in turn increases the pressure on the heat-affected zone, and the greater the work hardening, the more significant the increase in hardness in this area.

[0087] from Figure 8 It can be seen that after laser cladding of aluminum alloy, ultrasonic impact is performed. During ultrasonic impact, the cladding structure has cooled down and its plasticity is not as good as that of the cladding structure at high temperature. Under the same impact force, the deformation of the cladding structure is relatively small and the depth of the effect on the porosity defects is also small. Therefore, incompletely closed porosity defects can still be observed at the bottom of the cladding layer.

[0088] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, and not to limit them; although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some of the technical features; and these modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the spirit and scope of the technical solutions of the embodiments of the present invention.

Claims

1. An ultrasonic-assisted laser cladding device, characterized in that, include: A laser cladding head and an ultrasonic impact needle; the ultrasonic impact needle includes a shaft; the outer surface of the shaft is provided with a ceramic coating; The laser cladding head and the ultrasonic impact needle are located on the same side of the substrate to be repaired. The ultrasonic impact needle synchronously follows the laser cladding head, so that while the laser cladding head performs laser cladding on the substrate to be repaired to form a molten pool, the end face of the ultrasonic impact needle generates an impact pressure perpendicular to the substrate to be repaired.

2. The ultrasonic-assisted laser cladding device according to claim 1, characterized in that, The shaft is a columnar structure, with a first section, a second section and a third section arranged sequentially along its axial direction. The cross-sectional area of ​​each section is different, and the cross-sectional area of ​​the second section is smaller than that of the first section. The first segment is one end of the shaft, and its end face is a closed planar structure; The first segment and the second segment are coaxially connected, forming a stepped surface I at the connection between the two segments; The second segment is coaxially connected to the third segment, forming a stepped surface II at the junction of the two segments; The outer peripheral surface of the second segment, the surface of step surface I, and the surface of step surface II are provided with a ceramic coating.

3. The ultrasonic-assisted laser cladding device according to claim 1, characterized in that, The thickness of the ceramic coating is less than 1 mm, preferably 0.5 to 1 mm.

4. The method according to any one of claims 1 to 3, characterized in that, The minimum distance between the axis of the ultrasonic impact needle and the molten pool is 5~15 mm.

5. The method according to any one of claims 1 to 4, characterized in that, The laser cladding head includes a coaxial powder feeding nozzle.

6. A method for laser cladding and simultaneous ultrasonic impact forming of an aluminum alloy cladding layer, characterized in that, include: Using aluminum alloy powder as raw material, an aluminum alloy cladding layer is formed on the aluminum alloy substrate to be repaired using the ultrasonic-assisted laser cladding device described in any one of claims 1 to 5.

7. The method according to claim 6, characterized in that, The laser beam parameters include: the repair atmosphere is atmospheric; the energy distribution is a Gaussian beam; the spot diameter is 1~1.5mm; the laser power is 1600~1800W; the scanning speed is 300~900mm / min; the powder feeding rate is 1.0~2.5g / min; and the overlap rate is 40~50%.

8. The method according to claim 6 or 7, characterized in that, The impact pressure is 50~200N; Preferably, the ultrasonic impact gun has a frequency of 18~20KHz, a power of 600~1000W, and an amplitude of 35~40μm; the moving speed of the ultrasonic impact gun is consistent with the scanning speed of the laser beam.

9. The method according to any one of claims 6 to 8, characterized in that, The aluminum alloy powder is selected from AlSi10Mg and AlMgScZr.

10. An aluminum alloy part, characterized in that, The aluminum alloy part includes an aluminum alloy cladding layer, which is formed using the method described in any one of claims 6 to 9.

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