Method and device for repairing damaged part through laser fusion forging

Abstract

The invention provides a laser fusion forging repairing method and device for a damaged part, and relates to the technical field of metal part remanufacturing. The laser melting and forging repair device for the damaged part comprises a laser cladding module, a high-frequency micro-forging module, a multi-axis movement system, an online monitoring unit and an intelligent control center, wherein the laser cladding module is used for forming a molten pool in a damaged area of the damaged part and depositing metal powder; the high-frequency micro-forging module is used for generating picosecond laser pulses and applying synchronous laser impact forging in the solidification process of a molten pool; the multi-axis movement system is used for driving the laser cladding module and the high-frequency micro-forging module to move along a preset path; the online monitoring unit is used for collecting monitoring data in real time, and the monitoring data comprise the molten pool state and the forging effect. And the intelligent control center is used for receiving the monitoring data and adjusting the laser cladding parameters and the forging parameters in real time so as to repair the damaged part. According to the scheme, the method has the advantage that the mechanical property of the damaged part after laser melting forging repair is improved.

Description

Technical Field

[0001] This application relates to the field of metal component remanufacturing technology, and more specifically, to a method and apparatus for laser melting and forging repair of damaged components. Background Technology

[0002] High-value metal components operate under extreme conditions such as high temperature, high pressure, corrosion, and high-cycle fatigue, making them highly susceptible to localized damage such as wear, cracks, ablation, and corrosion pits. Taking high-pressure turbine blades for aero-engines as an example, the manufacturing cost of a single piece can reach hundreds of thousands of yuan, with a lengthy manufacturing cycle. Directly replacing them with new parts is uneconomical and results in slow supply chain response. Therefore, developing efficient and reliable remanufacturing and repair technologies to restore the performance and extend the lifespan of damaged components has become a key means to ensure the safe and economical operation of high-end equipment and promote circular manufacturing.

[0003] Laser cladding technology has become one of the mainstream approaches to metal component repair due to its advantages such as precise and controllable heat input, metallurgical bonding with the substrate, low dilution rate, and applicability to complex curved surfaces. This technology uses a high-energy laser beam to melt synchronously fed metal powder, which is then deposited layer by layer on the substrate surface to ultimately fill the damaged area. However, traditional laser cladding repair processes still suffer from problems such as uncontrollable metallurgical defects, residual stress concentration, and mismatch in mechanical properties. Summary of the Invention

[0004] The purpose of this application is to provide a method and apparatus for laser cladding repair of damaged components, so as to solve the problems of uncontrollable metallurgical defects, residual stress concentration and mechanical properties in the existing laser cladding repair process.

[0005] To achieve the above objectives, the technical solutions adopted in the embodiments of this application are as follows: On one hand, this application provides a laser cladding and forging repair device for damaged components. The device includes a laser cladding module, a high-frequency micro-forging module, a multi-axis motion system, an online monitoring unit, and an intelligent control center. The intelligent control center is connected to the laser cladding module, the high-frequency micro-forging module, the multi-axis motion system, and the online monitoring unit. Laser cladding modules are used to form a molten pool and deposit metal powder in the damaged area of ​​a damaged component; The high-frequency micro-forging module is used to generate picosecond laser pulses and apply synchronous laser shock forging during the solidification process of the molten pool; The multi-axis motion system is used to drive the laser cladding module and the high-frequency micro-forging module to move along a preset path; The online monitoring unit is used to collect monitoring data in real time, including the state of the molten pool and the forging effect; The intelligent control center is used to receive the monitoring data and adjust the laser cladding parameters and forging parameters in real time to repair the damaged parts.

[0006] Optionally, the high-frequency micro-forging module includes: Picosecond laser emitting unit, used to output laser beams with wavelengths of 532 nm or 1064 nm, pulse widths on the order of picoseconds, and repetition frequencies of 10 kHz to 1 MHz; A beam shaping and focusing system for compressing the laser beam into a micrometer-scale spot size; The synchronous motion platform is used to support the picosecond laser emitting unit and the beam shaping and focusing system, and to realize real-time tracking between the laser impact area and the molten pool area.

[0007] Optionally, the impact timing of the high-frequency micro-forging module covers 20% to 80% of the molten pool life cycle.

[0008] Optionally, the online monitoring unit includes: High-speed vision system for acquiring images of the molten pool; Infrared thermometers are used to monitor the temperature field of the molten pool; Acoustic emission sensors are used to detect the intensity of shock waves; A spectrometer is used for real-time analysis of the composition of the molten pool.

[0009] Optionally, the intelligent control center adopts a hierarchical closed-loop control architecture, which includes: The data acquisition layer is used to acquire real-time data on the morphology, temperature, and composition of the molten pool. The decision-making layer integrates a digital twin model and a reinforcement learning module to optimize process parameters based on data from the data acquisition layer and generate adjustment instructions. The execution layer is used to issue the adjustment commands via a real-time bus to adjust the laser power, forging frequency, and motion path; The safety monitoring layer is used to implement early warning of molten pool splash and module over-temperature protection.

[0010] On the other hand, this application also provides a laser melting and forging repair method for damaged components, applied to the aforementioned laser melting and forging repair device for damaged components, the method comprising: Perform 3D scanning and modeling of damaged components to generate repair paths; Laser cladding is initiated to form a molten pool in the damaged area, and metal powder is then introduced. During the solidification process of the molten pool, high-frequency picosecond laser shock forging is triggered simultaneously; The repair process involves layer-by-layer cladding and forging, with real-time monitoring of the molten pool status and forging effect, and dynamic adjustment of process parameters until the repair is complete.

[0011] Optionally, in the step of synchronously triggering high-frequency picosecond laser shock forging: The impact delay time is 1–5 ms; The impact window covers 20% to 80% of the molten pool's lifespan.

[0012] Optionally, the parameters of the high-frequency picosecond laser shock include: The pulse frequency is 10 kHz to 1 MHz; The single pulse energy is 0.5–2 mJ; The peak pressure of the shock wave is 2–5 GPa.

[0013] Optionally, in the step of layer-by-layer cladding and forging: Each cladding layer has a thickness of 0.2–0.5 mm; The overlap rate between layers is 30% to 50%; Each cladding layer is then subjected to laser impact forging.

[0014] Optionally, before initiating the laser cladding step, the method further includes: The damaged component is sandblasted and cleaned, and then preheated to 300±10℃.

[0015] Compared with the prior art, the embodiments of this application have the following beneficial effects: This application provides a method and apparatus for laser forging repair of damaged components. The apparatus includes a laser cladding module, a high-frequency micro-forging module, a multi-axis motion system, an online monitoring unit, and an intelligent control center. The intelligent control center is connected to the laser cladding module, the high-frequency micro-forging module, the multi-axis motion system, and the online monitoring unit. The laser cladding module forms a molten pool and deposits metal powder in the damaged area of ​​the component. The high-frequency micro-forging module generates picosecond laser pulses and applies synchronous laser shock forging during the solidification of the molten pool. The multi-axis motion system drives the laser cladding module and the high-frequency micro-forging module along a preset path. The online monitoring unit collects monitoring data in real time, including the molten pool state and forging effect. The intelligent control center receives the monitoring data and adjusts the laser cladding and forging parameters in real time to repair the damaged component.

[0016] This application adds a high-frequency micro-forging module and precisely synchronizes the high-frequency laser shock forging with the solidification process of the molten pool. The extremely high pressure and high-speed strain rate effect generated by the shock wave can break up growing dendrites, induce dynamic recrystallization, and compress the molten pool, forcing the dissolved gases inside to escape and compressing micro-shrinkage, significantly reducing porosity. At the same time, synchronous forging counteracts solidification shrinkage stress, forming a compressive stress layer on the surface of the repair area, which reduces metallurgical defects and residual tensile stress overall, and improves the mechanical properties of the damaged parts after laser melting and forging repair.

[0017] To make the above-mentioned objectives, features and advantages of this application more apparent and understandable, preferred embodiments are described below in detail with reference to the accompanying drawings. Attached Figure Description

[0018] To more clearly illustrate the technical solutions of the embodiments of this application, the accompanying drawings used in the embodiments will be briefly introduced below. It should be understood that the following drawings only show some embodiments of this application and should not be regarded as a limitation of the scope. For those skilled in the art, other related drawings can be obtained based on these drawings without creative effort.

[0019] Figure 1 This is a schematic diagram of the module of the laser melting and forging repair device for damaged components provided in the embodiments of this application.

[0020] Figure 2 A schematic diagram of the actual working condition of the laser melting and forging repair device for damaged components provided in the embodiments of this application.

[0021] Figure 3 An exemplary flowchart of a method for repairing damaged components provided in an embodiment of this application.

[0022] Figure 4 This is another exemplary flowchart of a method for repairing damaged components provided in an embodiment of this application.

[0023] Figure 5 This is a schematic diagram comparing the residual stress on the repaired surface of forged cladding and ordinary cladding, as provided in the embodiments of this application.

[0024] In the picture: 110 - Laser cladding module; 120 - High-frequency micro forging module; 130 - Multi-axis motion system; 140 - Online monitoring unit; 150 - Intelligent control center. Detailed Implementation

[0025] To make the objectives, technical solutions, and advantages of the embodiments of this application clearer, the technical solutions of the embodiments of this application will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of this application, and not all embodiments. The components of the embodiments of this application described and shown in the accompanying drawings can generally be arranged and designed in various different configurations.

[0026] Therefore, the following detailed description of the embodiments of this application provided in the accompanying drawings is not intended to limit the scope of the claimed application, but merely to illustrate selected embodiments of the application. All other embodiments obtained by those skilled in the art based on the embodiments of this application without inventive effort are within the scope of protection of this application.

[0027] It should be noted that similar reference numerals and letters in the following figures indicate similar items; therefore, once an item is defined in one figure, it does not need to be further defined and explained in subsequent figures. Furthermore, in the description of this application, terms such as "first," "second," etc., are used only to distinguish descriptions and should not be construed as indicating or implying relative importance.

[0028] It should be noted that in this paper, relational terms such as first and second are used only to distinguish one entity or operation from another entity or operation, and do not necessarily require or imply any such actual relationship or order between these entities or operations.

[0029] The following detailed description of some embodiments of this application is provided in conjunction with the accompanying drawings. Unless otherwise specified, the following embodiments and features can be combined with each other.

[0030] As described in the background section, traditional laser cladding repair processes still face numerous technical bottlenecks, limiting the application of repaired components in critical load-bearing scenarios. These bottlenecks are mainly manifested in the following ways: 1. Metallurgical defects are difficult to control effectively: The molten pool solidifies rapidly under extremely high temperature gradients, which easily forms coarse columnar crystal structures, accompanied by obvious elemental segregation. At the same time, the gas inside the molten pool does not have time to escape, forming defects such as pores and lack of fusion, which seriously affect the density and mechanical properties of the repair layer.

[0031] 2. Significant residual tensile stress problem: During laser cladding, the huge temperature difference between the cladding layer and the substrate leads to uneven thermal expansion and contraction, generating high residual tensile stress (typically exceeding +200MPa) within the repair area and at the interface. This tensile stress significantly reduces the fatigue strength of the component and may induce crack initiation and propagation during service, or even cause the repair layer to peel off.

[0032] 3. Mismatch between the mechanical properties of the repair layer and the substrate: Traditional cladding layers often have high hardness but insufficient plasticity and toughness. There is a significant abrupt change in properties between the repair area and the substrate, which can easily become a fatigue crack initiation under alternating loads, resulting in the overall fatigue life of the repaired part being much shorter than that of a new part.

[0033] To overcome these shortcomings, the industry has attempted various auxiliary or post-processing methods, but all have significant limitations. For example, vibration-assisted laser cladding technology attempts to break dendrites through external mechanical or ultrasonic vibration; however, the vibration wave transmission has a delay (typically >100 ms), making it impossible to precisely synchronize with the microsecond-level solidification process of the molten pool, resulting in limited grain refinement and weak porosity elimination. Alternatively, laser remelting post-processing technology involves a secondary scan of the cladding layer, using remelting thermal cycles to induce tissue recrystallization. This method expands the heat-affected zone, potentially causing matrix softening, and introduces additional heat input and deformation risks. Another approach is hot isostatic pressing (HIP), which places the repaired component in a high-temperature, high-pressure inert gas environment, using isotropic static pressure to eliminate internal porosity and promote creep healing. This method is extremely energy-intensive, has a long processing cycle, and is a post-processing of the entire component, making it unsuitable for localized repairs and economically inefficient.

[0034] It is evident that existing technologies struggle to simultaneously achieve the triple objectives of defect control, stress relief, and performance matching in a single repair process. Therefore, this application provides a laser melting and forging repair device for damaged components. This device simplifies the process flow, allows for in-situ control of defects during the cladding process, and enables precise control of these characteristics according to specific application requirements, significantly improving the mechanical properties of remanufactured damaged components. Furthermore, it enables dynamic grain refinement during the solidification process of the molten pool; reduces residual stress in the repair zone to below 30% of the matrix yield strength; and achieves fatigue performance of the repaired part exceeding 90% of that of a new part. The laser melting and forging repair device for damaged components provided in this application is described below as an example: As an optional implementation, please refer to Figure 1 and Figure 2 The laser melting and forging repair device for the damaged component includes: The system comprises a laser cladding module 110, a high-frequency micro-forging module 120, a multi-axis motion system 130, an online monitoring unit 140, and an intelligent control center 150. The intelligent control center 150 is connected to the laser cladding module 110, the high-frequency micro-forging module 120, the multi-axis motion system 130, and the online monitoring unit 140, respectively. The laser cladding module 110 forms a molten pool and deposits metal powder in the damaged area of ​​the damaged component. The high-frequency micro-forging module 120 generates picosecond laser pulses and applies synchronous laser shock forging during the solidification of the molten pool. The multi-axis motion system 130 drives the laser cladding module 110 and the high-frequency micro-forging module 120 along a preset path. The online monitoring unit 140 collects monitoring data in real time, including the molten pool state and forging effect. The intelligent control center 150 receives the monitoring data and adjusts the laser cladding and forging parameters in real time to repair the damaged component.

[0035] By adding a high-frequency micro-forging module 120 and precisely synchronizing the high-frequency laser shock forging with the solidification process of the molten pool, the extremely high pressure and high-speed strain rate effect generated by the shock wave can break up growing dendrites, induce dynamic recrystallization, and compress the molten pool, forcing the dissolved gases inside to escape and compressing micro-shrinkage, significantly reducing porosity. At the same time, synchronous forging counteracts solidification shrinkage stress, forming a compressive stress layer on the surface of the repair area, which overall reduces metallurgical defects and residual tensile stress, and improves the mechanical properties of the damaged parts after laser melting and forging repair.

[0036] In this application, the damaged component refers to a component made of metal material that has been damaged, such as having cracks or missing parts. In order to repair these damages, it is necessary to use a laser melting and forging repair device for damaged components to repair the damaged area.

[0037] Each module is described in detail below: The laser cladding module 110 is used to melt, transport, and deposit metal materials, thereby heating and melting the damaged area of ​​the damaged component to form a solid shape. It includes an optical path system and a powder feeding system. The optical path system includes a fiber laser, a collimating lens, and a focusing lens. For example, the fiber laser can be a laser with a wavelength of 1070±10nm, the collimating lens has a focal length of 100mm, and the focusing lens can have a focal length of 250mm and a working distance of 200mm. The spot diameter is continuously adjustable from 1.0 to 2.0mm, and the power density is ≥1×10⁻⁶. 5 W / cm². Understandably, the optical path system is mainly used to generate a laser that can form a molten pool in the damaged area. After the laser beam generated by the laser is collimated by the collimating lens and focused by the focusing lens, it only acts on the damaged area of ​​the damaged component and will not affect other areas.

[0038] The powder delivery system stably and continuously transports the metal powder (such as nickel-based alloys, titanium alloys, high-strength steel, etc.) used for repair from the powder storage tank to the laser action area. The powder is fed into the molten pool formed on the surface of the substrate (i.e. the damaged part) by the high-energy laser, where it is rapidly heated, melted, and metallurgically fused with the substrate material, thus accumulating layer by layer to eventually fill the damaged area and form a repair layer that is tightly bonded to the substrate.

[0039] The powder feeding system includes a three-channel annular nozzle and an airflow system. The inner diameter / outer diameter of the three-channel annular nozzle is Φ2mm / Φ6mm, and the carrier gas (argon) flow rate of the airflow system is 8-15L / min. The powder particle size is 45-150μm (adaptable design), and the powder feeding accuracy is ±0.5%.

[0040] The high-frequency micro-forging module 120 is used to apply instantaneous high-energy impact during the critical stage of molten pool solidification to achieve microstructure forging and stress control. It includes a picosecond laser emitting unit, a beam shaping and focusing system, and a synchronous motion platform.

[0041] The picosecond laser emitting unit is used to generate ultrashort pulse lasers for inducing shock waves. It employs a high-repetition-rate picosecond pulse laser with selectable output wavelengths of 532 nm or 1064 nm, pulse widths on the order of picoseconds, and single-pulse energy on the order of mJ, enabling stable operation at high frequencies (10 kHz to 1 MHz). Functionally, the picosecond laser emitting unit provides a shock energy source, with ultrashort pulses generating extremely high instantaneous power density on the material surface.

[0042] The beam shaping and focusing system is used to process the pulsed laser beam into the shape and size required for impact strengthening. It includes a beam expander, lens array, and focusing lens group, uniformly compressing the laser beam to a micrometer-scale spot size to ensure uniform distribution of impact energy on the cladding surface. On one hand, it achieves energy homogenization, preventing excessively high local energy from ablating the workpiece or excessively low energy from rendering the impact ineffective. Simultaneously, it enables spot compression, obtaining a small spot size to achieve high impact pressure. On the other hand, it can match the molten pool, allowing the impact area to effectively cover the width of the cladding channel.

[0043] A synchronous motion platform is used to link the high-frequency micro-forging module 120 and the laser cladding module 110. Through a multi-axis linkage platform, it achieves real-time tracking of the laser molten pool and the picosecond impact zone, ensuring precise temporal and spatial synchronization between the impact forging and the solidification process of the molten pool. Specifically, in terms of timing control, the synchronous motion platform receives a master control signal and, after the laser cladding has passed, triggers the impact with a precisely set time delay (Δt, e.g., 2ms), acting on the semi-solid or initial solidification stage of the molten pool. Furthermore, in one implementation, the impact timing of the high-frequency micro-forging module 120 covers 20% to 80% of the molten pool's lifespan. In terms of spatial tracking, the synchronous motion platform, through independent or linked motion mechanisms, ensures that the impact spot always follows behind the cladding head, performing full coverage or selective forging of the cladding layer along a preset path.

[0044] In some alternative implementations, the high-frequency micro-forging module 120 may also include a constraint layer / absorption layer system to enhance the peak pressure and duration of the laser-induced shock wave. For example, a light-absorbing material can be coated onto the workpiece surface as an absorption layer, covered with a transparent medium (such as glass) as a constraint layer. Plasma is generated by vaporization through the absorption layer, and the constraint layer restricts its expansion, thereby significantly increasing the shock wave pressure (up to several GPa).

[0045] The multi-axis motion system 130 is used to achieve precise, flexible, and complex relative motion between the repair tool (laser head) and the workpiece. It includes a six-axis robot with a load capacity of 50kg and a repeatability of ±0.03mm, equipped with a two-axis turntable (tilt angle ±180°, speed 10rpm), and a laser tracker to achieve real-time correction, update the workpiece pose every 50ms, compensate for thermal deformation errors, and compensate for path deviations caused by thermal deformation, clamping errors, or robot errors.

[0046] The online monitoring unit 140 includes a high-speed vision system for acquiring images of the molten pool; an infrared thermometer for monitoring the temperature field of the molten pool; an acoustic emission sensor for detecting the intensity of shock waves; and a spectrometer for real-time analysis of the composition of the molten pool.

[0047] The high-speed vision system captures images of the molten pool and its surroundings at a high frame rate (e.g., 5000 fps). Through image processing algorithms, such as Canny edge detection, it extracts the molten pool contour (accuracy ±5μm) and calculates key geometric parameters in real time, including the molten pool width, depth, trailing angle, and area. This allows it to identify abnormal fluctuations, spatter, humps, and other unstable phenomena in the molten pool. Optionally, the high-speed vision system may include a high-speed CCD / CMOS camera, high-brightness illumination (optional), and a specific wavelength narrowband filter (e.g., 808 nm) to eliminate plasma interference.

[0048] Furthermore, the online monitoring unit 140 of this application can achieve simultaneous temperature and spectrum acquisition: a dual-color infrared thermometer (800-2500℃) with a sampling rate of 1kHz; and a fiber optic spectrometer (200-800nm) to monitor the intensity of spectral lines of elements such as Fe, Cr, and Ni in real time, and to invert the composition of the molten pool. Specifically, temperature field monitoring uses a dual-color infrared thermometer or an infrared thermal imager to measure the temperature of the center, tail, and heat-affected zone of the molten pool in real time, and to perform temperature gradient analysis. An acoustic emission sensor is used to acquire stress wave signals generated by laser shock forging. By analyzing the amplitude, energy, and count rate of the acoustic emission signal, the effectiveness and consistency of each impact can be indirectly evaluated, and the elastic waves released when microcracks are generated or propagated within the material can be captured. A plasma spectrum of the molten pool is used to acquire the plasma spectrum in real time and analyze the intensity of characteristic spectral lines such as Fe, Cr, and Ni. The stability of the spectral signal reflects the stability of the molten pool evaporation and ionization process, indirectly characterizing the process stability. By monitoring the relative changes in the intensity of the spectral lines of the matrix elements and powder elements, the mixing ratio of the matrix material in the cladding layer can be estimated.

[0049] As one implementation method, the intelligent control center 150 is used for information fusion, intelligent decision-making, and collaborative control to achieve autonomous optimization of the repair process. It adopts a hierarchical closed-loop control architecture, which includes: a data acquisition layer for real-time acquisition of molten pool morphology, temperature, and composition data; a decision layer integrating a digital twin model and reinforcement learning module to optimize process parameters based on data from the data acquisition layer and generate adjustment commands; an execution layer for issuing adjustment commands via a real-time bus to adjust laser power, forging frequency, and motion path; and a safety monitoring layer for implementing molten pool splash warnings and module over-temperature protection.

[0050] Specifically, the data acquisition layer acquires real-time data on molten pool morphology, temperature gradient, and composition using a high-speed CCD, dual-color infrared thermometer, and spectrometer. Edge detection algorithms are then used to extract the molten pool aspect ratio and temperature field distribution. The decision-making layer integrates a digital twin model and rule base, combining reinforcement learning modules to optimize process parameters. The execution layer issues commands via the EtherCAT bus to dynamically adjust laser power, forging frequency, and robot path. The safety monitoring layer implements dual-threshold molten pool splash warnings and forging head overheat protection to ensure a response time of <10ms throughout the entire process. Data from each layer interacts through a real-time database, achieving a fully closed-loop control system of "perception-decision-execution-verification."

[0051] Based on the above implementation, this application also provides a laser melting and forging repair method for damaged components, applied to the aforementioned laser melting and forging repair device for damaged components. Please refer to [link to relevant documentation]. Figure 3 The method includes: S102, perform 3D scanning and modeling of the damaged component, and generate a repair path.

[0052] S104, initiate laser cladding, form a molten pool in the damaged area and feed in metal powder.

[0053] S106, during the solidification process of the molten pool, is simultaneously triggered by high-frequency picosecond laser impact forging.

[0054] S108 involves layer-by-layer cladding and forging according to the repair path, real-time monitoring of the molten pool status and forging effect, and dynamic adjustment of process parameters until the repair is completed.

[0055] In S102, three-dimensional laser scanning can be used to accurately obtain the defect range and depth of damaged components. The detection data is then converted into point cloud files and a CAD / CAE model is established. Finite element meshes (element size 0.05~0.1 mm) are generated for the damaged area, and thermo-mechanical coupling simulation is performed to predict the deformation and residual stress distribution during the repair process. An optimized repair path is generated based on the simulation results.

[0056] As one implementation method, please refer to step S104 before proceeding. Figure 4 The method also includes: S103, the damaged component is sandblasted and cleaned, and the damaged component is preheated to 300±10℃.

[0057] For example, Al2O3 sandblasting (particle size #60, air pressure 0.6 MPa) can be used to remove the surface oxide layer and impurities; then, ultrasonic cleaning with acetone for 20 min can be performed to ensure that there is no oil residue on the surface; and the damaged part can be preheated to 300°C to reduce the temperature gradient and avoid cold cracking. At the same time, severely damaged areas can be lightly machined to form regular repair grooves to ensure the bonding interface of the cladding layer.

[0058] The aforementioned pretreatment process makes the damaged area of ​​the component more regular, resulting in better repair outcomes. Furthermore, preheating the damaged component to 300°C reduces the temperature difference between the laser-heated component and the damaged component during subsequent laser repair, thereby minimizing stress.

[0059] When starting laser cladding, select appropriate powder materials (such as nickel-based alloys, titanium alloys, or high-strength steel alloy powders) with a particle size distribution of 45~105 μm; feed them into the molten pool at a rate of 8~12 g / min through a powder feeding system, use argon as the protective gas with a flow rate of 15~25 L / min; set parameters such as laser power, scanning speed, and spot diameter according to the material type to ensure stable formation of the molten pool.

[0060] Furthermore, after laser cladding is initiated and the laser molten pool is formed under synchronous control of melting and forging, the control system delays by 1 to 5 ms, for example, Δt = 2 ms to trigger picosecond laser shock; and the pulse frequency of the high-frequency micro-forging module 120 is 10 kHz to 1 MHz; the single pulse energy is 0.5 to 2 mJ; the peak pressure of the shock wave is 2 to 5 Gpa; the shock timing covers 20% to 80% of the molten pool life cycle; the path adopts a coaxial synchronous / para-axial staggered mode to ensure uniform coverage of cladding and forging.

[0061] Next, multi-layer cladding and layered forging are performed layer by layer according to the repair path, with each cladding layer having a thickness of 0.2–0.5 mm and an interlayer overlap rate of 30%–50%. Laser shock blasting is performed after each cladding layer. Specifically, when the repair layer thickness is >1 mm, a layer-by-layer cladding and forging process is adopted; the thickness of each layer is controlled at 0.3–0.5 mm, and the interlayer overlap rate is ≥40%; picosecond laser shock blasting is performed immediately after each cladding layer to ensure multi-layer grain refinement and residual stress control.

[0062] During the repair process, it is necessary to monitor the state of the molten pool and the forging effect as needed, and dynamically adjust the process parameters until the repair is completed. The system integrates an infrared thermometer to monitor the surface temperature of the molten pool in real time (accuracy ±2℃, sampling frequency 10 kHz); the intensity and uniformity of the shock wave are detected by an acoustic emission sensor; the control system is based on a feedback algorithm to dynamically adjust the picosecond pulse energy, frequency and cladding laser power to achieve three-parameter linkage closed-loop control.

[0063] During the repair process, if the hardness of the repaired area is greater than the set threshold and the stress and porosity are less than the corresponding threshold, the repair is considered complete. At this time, the repair layer can be cooled and post-treated. For example, it can be naturally cooled to room temperature under a protective atmosphere. If necessary, annealing heat treatment (such as holding at 650℃ for 2 hours) can be performed to release some residual stress. CNC precision machining or electrical discharge machining can be used to restore the original size and surface finish of the part (Ra ≤ 0.8 μm).

[0064] Afterwards, monitoring and performance verification can be carried out, namely, metallographic examination, hardness testing, and fatigue life testing of the repaired area; non-destructive testing (ultrasound, X-ray or CT) confirms that there are no pores or cracks inside the repair layer; compared with the original material performance, the microhardness of the repaired area is increased by 20-50%, the fatigue life is increased by 2-4 times, and the corrosion resistance is significantly enhanced.

[0065] This application utilizes in-situ composite control of high-repetition-rate ultrafast lasers to control laser cladding, achieving significant beneficial effects in terms of surface and interface performance, process efficiency, and applicability. Specifically, these effects are reflected in the following aspects: 1. Breakthrough Improvement in Microstructure Properties. Grain Refinement: Traditional laser repair has a grain size >35μm (mainly columnar crystals). This application precisely synchronizes high-frequency laser shock forging with the molten pool solidification process. The extremely high pressure and high-speed strain rate effect generated by the shock wave breaks up growing dendrites, increases nucleation points, and promotes the formation of equiaxed crystals. At the same time, it induces dynamic recrystallization, obtaining a uniform and fine grain structure (e.g., refining the grain size from >35 μm in traditional cladding to 10-20 μm), significantly improving crack propagation resistance. On the other hand, this method can compress the molten pool, forcing the dissolved gas inside to escape and compressing micro-shrinkage, significantly reducing porosity (down to below 0.5%), thereby fundamentally improving the metallurgical quality of the repair layer.

[0066] 2. Residual Stress Optimization. Active control and optimization of the residual stress state are achieved: Synchronous laser shock introduces a plastic compressive strain layer hundreds of micrometers deep into the surface of the repair area. This compressive strain layer effectively counteracts the tensile stress generated by the solidification shrinkage of the cladding layer, and even forms beneficial residual compressive stress on the surface of the repair area, such as -100 MPa to -400 MPa (compared to +200 MPa tensile stress in traditional processes). This compressive stress layer can significantly inhibit the initiation and early propagation of fatigue cracks, resulting in a 120% increase in fatigue life. Figure 5 As shown, the residual stress on the surface of the conventional cladding used in the prior art is +200MPa tensile stress after repair, while the residual stress on the surface of the forging cladding used in this application is -100MPa after repair.

[0067] 3. Improved Mechanical Properties. The combined effect of fine-grained strengthening and work hardening, while maintaining or slightly improving strength and hardness, significantly improves the performance gradient between the plasticity and toughness repair layer and the matrix, resulting in a smoother interface bonding strength and avoiding weak points caused by abrupt performance changes. Corrosion resistance and wear resistance are also simultaneously improved due to the dense structure and uniform composition. Verification shows that the tensile strength provided by this application increases from 85-90% of the matrix to 98%, an increase of 10-13%; the elongation increases from 40-50% of the matrix to 90%, an increase of 80-100%.

[0068] 4. Revolutionary improvements in efficiency and cost. Simplified process: cladding, forging, and strengthening are completed simultaneously, shortening the cycle by 60% compared to the "cladding + HIP post-treatment" solution (reducing the repair time of a gas turbine blade from 8 hours to 3.2 hours); Reduced energy consumption: eliminating the hot isostatic pressing process (single time >200kWh), resulting in a 70% reduction in overall energy consumption; Material savings: closed-loop powder feeding control enables powder utilization to reach 95% (traditional methods ≤80%).

[0069] The following section uses a certain type of turbine blade as an example to fully illustrate its repair process: S1, Preparations before repair Damage assessment: Taking a certain type of turbine blade as an example, the blade has a chord length of 120 mm, a thickness of 3.5 mm, and a wear depth of 1.2 mm.

[0070] 3D scanning: A point cloud model was generated using a laser line scanner (accuracy 0.02 mm), with a wear area of ​​382 mm². 2 .

[0071] Surface pretreatment: Sandblasting: Al2O3 abrasive particles (#80 mesh), surface roughness Ra=3.2 μm; Cleaning: Ultrasonic cleaning with acetone for 20 minutes, followed by drying in an oven at 80°C; Preheating: Induction heating to 300±10℃ to reduce thermal stress concentration.

[0072] S2: Repair parameter settings Laser cladding: Light source: IPG YLS-3000 fiber laser; Power 1850 W, spot diameter Φ1.2 mm, powder feeding rate 12 g / min; Powder delivery method: Coaxial air-carrying powder delivery (carrying gas Ar 99.999%, flow rate 18 L / min); High-frequency picosecond laser shock micro-forging: Laser: Nd:YVO4 picosecond laser, wavelength 1064 nm, pulse width 10 ps; The pulse frequency is 100 kHz, and the single pulse energy is 0.8 mJ. The impact delay Δt = 2 ms, and the effect window covers 20%~80% of the molten pool's lifespan; The peak pressure of the shock wave is approximately 3.5 GPa; Movement path: Layer thickness 0.2 mm, overlap rate 35%, scanning speed 8 mm / s; The six-axis robot (KUKA KR 60-3) enables multi-axis linkage and complex surface coverage.

[0073] S3: Repair Process Control Molten pool control: Real-time monitoring of the molten pool width-to-depth ratio (W / D). When W / D = 1.9, the parameter is maintained; when W / D > 2.1, the power is automatically reduced by 50 W. Temperature control: Infrared temperature measurement is fed back to the PID controller to maintain a temperature gradient of G=3.2×104 K / m (fluctuation ≤±10%). Shock closed-loop regulation: The acoustic emission sensor monitors the intensity of the shock wave. When the intensity fluctuation exceeds ±5%, the picosecond laser single pulse energy is automatically adjusted to ±0.05 mJ.

[0074] S4: Post-processing and performance testing Heat treatment: vacuum furnace cooling at 720℃ for 8 hours → air cooling at 620℃ for 8 hours to further release residual stress; Non-destructive testing: X-ray inspection according to ASTM E1742 standard, porosity 0.18% (Φ<0.1 mm), no through cracks found; Residual stress test: The surface layer of the repaired area has a compressive stress of approximately -320 MPa (within a depth of 150 μm), which significantly improves fatigue resistance; Microhardness: The repair layer has an HV0.2 of 465, which is approximately 28% higher than that of the substrate; Fatigue life test: Under 650℃ conditions, the fatigue life of the repaired blade was increased to 2.6 times that of the original blade.

[0075] As can be seen, the repair method provided in this application can transform residual tensile stress on the surface into compressive stress, which is suitable for the efficient repair of metallic materials and can solve the problems of weak interfacial bonding and poor fatigue resistance of components.

[0076] In summary, this application provides a method and apparatus for laser forging repair of damaged components. The apparatus includes a laser cladding module, a high-frequency micro-forging module, a multi-axis motion system, an online monitoring unit, and an intelligent control center. The intelligent control center is connected to the laser cladding module, the high-frequency micro-forging module, the multi-axis motion system, and the online monitoring unit. The laser cladding module forms a molten pool and deposits metal powder in the damaged area of ​​the component. The high-frequency micro-forging module generates picosecond laser pulses and applies synchronous laser shock forging during the solidification of the molten pool. The multi-axis motion system drives the laser cladding module and the high-frequency micro-forging module along a preset path. The online monitoring unit collects monitoring data in real time, including the molten pool state and forging effect. The intelligent control center receives the monitoring data and adjusts the laser cladding parameters and forging parameters in real time to achieve the repair of the damaged component. This application adds a high-frequency micro-forging module and precisely synchronizes the high-frequency laser shock forging with the solidification process of the molten pool. The extremely high pressure and high-speed strain rate effect generated by the shock wave can break up growing dendrites, induce dynamic recrystallization, and compress the molten pool, forcing the dissolved gases inside to escape and compressing micro-shrinkage, significantly reducing porosity. At the same time, synchronous forging counteracts solidification shrinkage stress, forming a compressive stress layer on the surface of the repair area, which reduces metallurgical defects and residual tensile stress overall, and improves the mechanical properties of the damaged parts after laser melting and forging repair.

[0077] The above description is merely a preferred embodiment of this application and is not intended to limit this application. Various modifications and variations can be made to this application by those skilled in the art. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of this application should be included within the protection scope of this application.

[0078] It will be apparent to those skilled in the art that this application is not limited to the details of the exemplary embodiments described above, and that this application can be implemented in other specific forms without departing from the spirit or essential characteristics of this application. Therefore, the embodiments should be considered illustrative and non-limiting in all respects, and the scope of this application is defined by the appended claims rather than the foregoing description. Thus, all variations falling within the meaning and scope of equivalents of the claims are intended to be included within this application. No reference numerals in the claims should be construed as limiting the scope of the claims.

Claims

1. A laser melting and forging repair device for damaged components, characterized in that, The laser cladding and forging repair device for damaged components includes a laser cladding module, a high-frequency micro-forging module, a multi-axis motion system, an online monitoring unit, and an intelligent control center. The intelligent control center is connected to the laser cladding module, the high-frequency micro-forging module, the multi-axis motion system, and the online monitoring unit. Laser cladding modules are used to form a molten pool and deposit metal powder in the damaged area of ​​a damaged component; The high-frequency micro-forging module is used to generate picosecond laser pulses and apply synchronous laser shock forging during the solidification process of the molten pool; The multi-axis motion system is used to drive the laser cladding module and the high-frequency micro-forging module to move along a preset path; The online monitoring unit is used to collect monitoring data in real time, including the state of the molten pool and the forging effect; The intelligent control center is used to receive the monitoring data and adjust the laser cladding parameters and forging parameters in real time to repair the damaged parts.

2. The laser melting and forging repair device for damaged components according to claim 1, characterized in that, The high-frequency micro-forging module includes: Picosecond laser emitting unit, used to output laser beams with wavelengths of 532 nm or 1064 nm, pulse widths on the order of picoseconds, and repetition frequencies of 10 kHz to 1 MHz; A beam shaping and focusing system for compressing the laser beam into a micrometer-scale spot size; The synchronous motion platform is used to support the picosecond laser emitting unit and the beam shaping and focusing system, and to realize real-time tracking between the laser impact area and the molten pool area.

3. The laser melting and forging repair device for damaged components according to claim 1, characterized in that, The impact timing of the high-frequency micro-forging module covers 20% to 80% of the life cycle of the molten pool.

4. The laser melting and forging repair device for damaged components according to claim 1, characterized in that, The online monitoring unit includes: High-speed vision system for acquiring images of the molten pool; Infrared thermometers are used to monitor the temperature field of the molten pool; Acoustic emission sensors are used to detect the intensity of shock waves; A spectrometer is used for real-time analysis of the composition of the molten pool.

5. The laser melting and forging repair device for damaged components according to claim 1, characterized in that, The intelligent control center adopts a hierarchical closed-loop control architecture, which includes: The data acquisition layer is used to acquire real-time data on the morphology, temperature, and composition of the molten pool. The decision-making layer integrates a digital twin model and a reinforcement learning module to optimize process parameters based on data from the data acquisition layer and generate adjustment instructions. The execution layer is used to issue the adjustment commands via a real-time bus to adjust the laser power, forging frequency, and motion path; The safety monitoring layer is used to implement early warning of molten pool splash and module over-temperature protection.

6. A method for laser melting and forging repair of damaged components, characterized in that, The method, applied to the laser melting and forging repair apparatus for damaged components as described in any one of claims 1 to 5, comprises: Perform 3D scanning and modeling of damaged components to generate repair paths; Laser cladding is initiated to form a molten pool in the damaged area, and metal powder is then introduced. During the solidification process of the molten pool, high-frequency picosecond laser shock forging is triggered simultaneously; The repair process involves layer-by-layer cladding and forging, with real-time monitoring of the molten pool status and forging effect, and dynamic adjustment of process parameters until the repair is complete.

7. The laser melting and forging repair method for damaged components according to claim 6, characterized in that, In the step of synchronously triggering high-frequency picosecond laser shock forging: The impact delay time is 1–5 ms; The impact window covers 20% to 80% of the molten pool's lifespan.

8. The laser melting and forging repair method for damaged components according to claim 6, characterized in that, The parameters of the high-frequency picosecond laser shock include: The pulse frequency is 10 kHz to 1 MHz; The energy of a single pulse is 0.5–2 mJ; The peak pressure of the shock wave is 2–5 GPa.

9. The laser melting and forging repair method for damaged components according to claim 6, characterized in that, In the step of layer-by-layer cladding and forging: Each cladding layer has a thickness of 0.2–0.5 mm; The overlap rate between layers is 30% to 50%; Each cladding layer is then subjected to laser impact forging.

10. The laser melting and forging repair method for damaged components according to claim 6, characterized in that, Prior to initiating the laser cladding step, the method further includes: The damaged component is sandblasted and cleaned, and then preheated to 300±10℃.

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