Apparatus and method for laser-pulse current coupling additive manufacturing of 17-4PH steel

Abstract

This invention belongs to the field of laser additive manufacturing technology, specifically relating to an apparatus and method for laser-pulsed current coupled additive manufacturing of 17-4PH steel using a co-feeding wire-powder system. Addressing the problems of insufficient residual δ-ferrite and insufficient precipitation of nano-copper-rich phases in existing 17-4PH steel laser additive manufacturing processes, as well as the inability of existing control technologies to simultaneously address the differentiated requirements of solidification and aging, and the difficulty in achieving in-situ composition control and multi-process synergy, this invention proposes a full-chain synergistic optimization technology solution. This invention utilizes synergistic control methods such as laser heat source, co-feeding of wire and powder, pulsed current application, and closed-loop monitoring to in-situ adjust the molten pool composition and solidification behavior during the 17-4PH stainless steel laser additive manufacturing process, suppressing residual δ-ferrite and accelerating the precipitation of nano-copper-rich phases. This results in printed components with low residual δ-ferrite, high hardness, and high strength without post-heat treatment, suitable for manufacturing large and complex components and on-site repair of damaged parts.

Description

Technical Field

[0001] This invention relates to the field of laser additive manufacturing technology, specifically to an apparatus and method for additive manufacturing 17-4PH precipitation-hardening stainless steel using laser-pulse current coupling with co-feeding wire and powder, belonging to the interdisciplinary field of materials forming and electromagnetic metallurgy. Background Technology

[0002] In recent years, laser-directed energy deposition additive manufacturing (LDED) technology has become a key technology for the integrated manufacturing and on-site repair of core components of high-end equipment. The uniformity of the microstructure and mechanical properties of the formed parts directly determine the service safety and reliability of key components in aerospace, energy equipment, and other fields. Among them, 17-4PH precipitation-hardening stainless steel, with its excellent strength, toughness, and corrosion resistance, has become an important material for the laser additive manufacturing of large and complex load-bearing components. It should be noted that during the laser additive manufacturing process, due to the inherent characteristics of the solidification mode and the extreme non-equilibrium thermal history, this material is prone to metallurgical defects such as residual δ-ferrite and insufficient precipitation of copper-rich nanophases (CRPs). This makes the control of solidification microstructure and the precipitation of strengthening phases the core links to ensure that its performance meets the standards.

[0003] In existing laser additive manufacturing processes for 17-4PH steel, the forming control is typically achieved by using pre-alloyed powder with fixed composition and preset constant laser process parameters. Post-printing solution treatment followed by aging heat treatment is then used to achieve microstructure homogenization and the precipitation of strengthening phases. For example, standard 17-4PH pre-alloyed powder is selected, and fixed laser power and scanning rate are set to complete layer-by-layer deposition. After forming, the entire structure undergoes overall heat treatment to meet performance requirements.

[0004] However, in the actual laser additive manufacturing process of 17-4PH steel, two major insurmountable defects often arise due to the material's inherent solidification characteristics and extreme non-equilibrium thermal history:

[0005] Firstly, the chromium equivalent to nickel equivalent ratio of the standard 17-4PH composition is 2.7-3.0, indicating a fully ferrite solidification mode. The high cooling rate of laser additive manufacturing inhibits sufficient element diffusion, resulting in an incomplete solid-state phase transformation from δ-ferrite to austenite, ultimately leaving a high residual content in the microstructure. The network of δ-ferrite disrupts the continuity of the martensitic matrix. The reason for this is that, in the all-ferrite solidification mode, the high-temperature δ-ferrite must transform into austenite through a peritectic / eutectoid reaction during subsequent solid-state cooling. This transformation depends on the diffusion and redistribution of elements such as Cr and Ni. However, the cooling rate in laser additive manufacturing is as high as... The rate of change is much faster than the rate of elemental diffusion, and the transformation is kinetically suppressed, so that the residual δ-ferrite is retained along the solidification grain boundaries and dendrites until room temperature.

[0006] Secondly, during the subsequent thermal cycling of the deposited layers, the residence time in the equivalent aging stage of the printed component is extremely short. This results in insufficient driving force for the precipitation of copper-rich nanoparticles, inadequate diffusion, low precipitation density, and uneven size of the precipitated phases. The hardness of the printed component is typically only 280-320 HV, far lower than that of the heat-treated forging. The root cause is that the precipitation of copper-rich nanoparticles follows a classic nucleation-growth mechanism, requiring sufficient diffusion time within the aging temperature range of 450-600℃ to allow copper atoms to complete long-range diffusion and form stable nuclei above the critical size. In contrast, in laser additive manufacturing, the cumulative residence time in the equivalent aging temperature range is only a few seconds to tens of seconds, and the diffusion kinetics are far from meeting the requirements for complete precipitation.

[0007] The aforementioned problems severely restrict the direct application of large and complex components without post-processing, and also greatly limit the reliability of the process and the quality of repair in on-site repair scenarios.

[0008] To address the above problems, existing technologies have proposed several improvement solutions:

[0009] Some solutions involve adjusting the Cr and Ni content through pre-alloyed powder composition design to reduce... The ratio can suppress the formation of δ-ferrite from the perspective of material design. However, this type of solution uses pre-alloyed powder with a fixed composition, which cannot flexibly adjust the composition and properties in different regions of the same component, and also cannot solve the problem of insufficient CRP precipitation.

[0010] Another approach attempts to promote CRP precipitation by optimizing laser process parameters and adjusting thermal history, but due to limitations in forming quality and efficiency, the adjustment space for process parameters is limited, making it difficult to fundamentally solve the problem of insufficient precipitation kinetics.

[0011] Another approach involves post-additive heat treatment, which eliminates δ-ferrite and promotes CRP precipitation through solution treatment and aging after printing. Unfortunately, this method is not suitable for on-site repair of large components, and overall heat treatment can easily lead to component deformation and secondary damage.

[0012] In recent years, pulsed current assisted additive manufacturing technology has gradually attracted attention. It controls the microstructure through electromagnetic stirring and Joule heating effect of pulsed current. It is worth noting that the existing pulsed current technology adopts a single fixed parameter mode, which cannot take into account the differentiated control needs of the solidification stage and the aging stage. Moreover, this type of technology is not combined with composition control, and cannot solve the root cause problem of δ ferrite residue at the material level.

[0013] In addition, technologies such as wire-powder co-feeding and interlayer pauses have also been attempted for microstructure control in additive manufacturing. For example, Chinese patent CN119549735A discloses a method for wire-powder co-feeding multimodal laser coupling additive manufacturing of titanium alloys, which can achieve wire-powder switching to balance processing efficiency and accuracy. However, this scheme focuses on wire-powder switching, and the lack of pulse current makes it lack the physical mechanism to regulate solidification structure and promote aging precipitation. In addition, the above patents mainly target titanium alloys and do not involve the synergistic control of δ-ferrite residue and copper-rich phase precipitation in 17-4PH steel. Therefore, they are difficult to directly apply to the technical problems solved by this invention.

[0014] In summary, existing technologies treat composition control and physical field control as separate entities, and the pulsed currents all employ a single fixed parameter mode, failing to address the differentiated control requirements of the solidification and aging stages. Therefore, how to achieve precise control of solidification structure and aging-enhanced phase infiltration simultaneously through deep coupling of wire-powder co-feeding and staged variable-parameter pulsed currents, thereby overcoming the shortcomings of existing technologies in addressing the dual challenges of residual δ-ferrite and insufficient CRP precipitation, has become a pressing technical challenge in this field. Summary of the Invention

[0015] An apparatus for laser-pulse current coupled additive manufacturing of 17-4PH steel using a co-feeding wire-powder system is characterized by comprising the following components: a laser heat source system, including a fiber laser, a laser transmission fiber, and a laser processing head; the fiber laser has a power range of 300-6000W and supports continuous mode; the laser processing head employs a reflective optical design to focus the laser at a single point, which is contained within an annular powder feeding channel; the laser processing head has internal gaps and a reflective optical design; a rolling electrode inside the laser head and a wire feeding tube inside the laser heat source system deliver the wire. The laser powder confluence point; the wire-powder co-feeding system includes a coaxial powder feeding mechanism, a coaxial wire feeding mechanism, a powder feeder, and a wire feeder. The powder feeder is a multi-hopper design, including at least three independent hoppers, respectively filled with high-Ni powder, high-Cr powder, and high-Cu powder. Each hopper is equipped with an independent powder feeding tray, a powder feeding motor, and a flow controller, enabling independent and precise control of the three powder feeding speeds. The wire feeder conveys 17-4PH stainless steel wire; the pulse current generation and application system includes a pulse power supply, a rolling electrode device, and a conductive clamp; the pulse power supply has a laser deposition mode. The system has two preset parameter modes: a deposition mode and an interlayer pause mode, which can automatically switch between the two modes based on the laser switching signal. The positive electrode is connected to two wires, one to the rolling electrode and the other to one end of the conductive clamp. When the positive wire is connected to the rolling electrode, it is in deposition mode; when connected to the conductive clamp, it is in interlayer pause mode. The negative electrode is connected to the other end of the conductive clamp. The rolling electrode is used to assist in conductivity and guide the filament, allowing current to be conducted to the molten pool area. The system also includes a data acquisition and monitoring module, comprising a laser status module and a filament powder feeding monitoring module. The monitoring module acquires the laser's on / off status signal in real time. The wire powder feeding monitoring module can monitor and change the feeding rate in real time. The motion and control system includes a six-axis robot and a positioner; an inert gas protection system includes an argon cylinder and a gas flow meter; and a control terminal is electrically connected to the laser, powder feeder, wire feeder, pulse power supply, robot, and positioner to adjust the laser power, powder feeding rate, wire feeding rate, and pulse current parameters according to the laser and feeding status. Each system is controlled by the control terminal, which provides feedback adjustment based on monitoring information. The device for wire-powder co-feeding laser-pulse current coupled additive manufacturing of 17-4PH steel is described below. Figure 1 As shown.

[0016] An apparatus for additive manufacturing of 17-4PH steel using laser-pulsed current coupling with co-feeding of wire powder, characterized in that: the pulsed current parameters of the laser deposition mode are: peak current 400-600A, frequency 50-150Hz, pulse width 2000-5000μs, and duty cycle... The parameter group A, characterized by a lower frequency and a higher amplitude, aims to enhance the electromagnetic stirring and electromigration effects, promoting compositional homogenization within the molten pool and the transformation of δ-ferrite to austenite. The pulse current parameters for the interlayer pause mode are: peak current 150-300A, frequency 500-1500Hz, pulse width 200-600μs, and duty cycle... The parameter group B, characterized by higher frequency and lower amplitude, is designed to enhance Joule thermal and non-thermal effects (reducing diffusion activation energy and promoting Cu diffusion through electromigration), thereby accelerating the nucleation and growth of CRPs in the martensitic matrix.

[0017] An apparatus for laser-pulse current coupled additive manufacturing of 17-4PH steel using wire and powder co-feeding, characterized in that: the high-Ni powder is pure Ni powder or Ni-based alloy powder, with a Ni content of... Used to improve the molten pool Value; the high-Cr powder is pure Cr powder or Cr-based alloy powder, with a Cr content of Used to regulate the molten pool Value; the high-copper powder is pure Cu powder or Cu-based alloy powder, with a Cu content of It is used to supplement the Cu content to increase the driving force for CRP precipitation.

[0018] An apparatus for additive manufacturing of 17-4PH steel using laser-pulse current coupling with co-feeding of wire powder, characterized in that: the laser deposition / interlayer pause dual-mode control module further includes an interlayer pause time management submodule, which starts a timer when the laser state changes from on to off, and allows the next layer deposition to begin after the interlayer pause time reaches a preset value.

[0019] An apparatus for laser-pulse current coupled additive manufacturing of 17-4PH steel using wire powder delivery, characterized in that: the interlayer pause time is set in the range of 0-300s, preferably 10-60s.

[0020] A device for laser-pulsed current coupled additive manufacturing of 17-4PH steel using wire and powder feeding, characterized in that: the device further includes a real-time calculation and control system for the molten pool composition, the system comprising a feeding parameter acquisition module, a molten pool composition calculation module, and a feeding parameter optimization module; the feeding parameter acquisition module acquires the wire feeding speed and the powder feeding speed of each hopper in real time; the molten pool composition calculation module calculates the molten pool composition in real time based on the law of conservation of mass. The ratio and Cu content; the feeding parameter optimization module adjusts the powder feeding speed of each hopper using a PID algorithm based on the deviation between the target composition and the actual composition.

[0021] An apparatus for co-feeding wire powder and laser-pulse current coupled additive manufacturing of 17-4PH steel, characterized in that: The target value for the ratio is 1.0-1.5, and the target value for the Cu content is 4.5-8.0 wt%.

[0022] A method for additive manufacturing of 17-4PH steel using laser-pulse current coupling with wire and powder feeding, characterized by the following steps: (a) using 17-4PH stainless steel wire as the matrix material supply source, and using high-Ni powder, high-Cr powder, and high-copper powder as the composition-controlled powder source, the material is transported to the laser molten pool through wire and powder co-feeding to achieve molten pool formation. (a) In-situ control of ratio and Cu content; (b) During the laser deposition stage, the laser is turned on and a pulsed current mainly composed of electromagnetic stirring and electromigration is applied to the molten pool to suppress δ-ferrite residue and refine the grains; (c) After the current layer is deposited, the laser is turned off and the interlayer pause stage is entered; (d) During the interlayer pause stage, a pulsed current mainly composed of Joule heating and non-thermal effects is applied to the solidified layer to accelerate the precipitation of nano-copper-rich phase; (e) After the interlayer pause is completed, return to step (b) and start the next layer deposition until the component is completed.

[0023] A method for additive manufacturing of 17-4PH steel using laser-pulsed current coupling with co-feeding wire powder, characterized in that: the parameters of the pulsed current in step (b) are: peak current 400-600A, frequency 50-150Hz, pulse width 2000-5000μs, and duty cycle... The parameters of the pulse current in step (d) are: peak current 150-300A, frequency 500-1500Hz, pulse width 200-600μs, and duty cycle. .

[0024] A method for additive manufacturing of 17-4PH steel using laser-pulse current coupling with co-feeding wire powder, characterized in that the interlayer pause time is 10-60s.

[0025] A method for laser-pulse current coupled additive manufacturing of 17-4PH steel using co-feeding of wire powder and powder is characterized in that: in step (a), the feed rate of high-Ni powder and high-copper powder is adjusted to control the molten pool in real time. The ratio and Cu content make The ratio was maintained at 1.0-1.5, and the Cu content was maintained at 4.5-8.0 wt%.

[0026] A method for laser-pulse current coupled additive manufacturing of 17-4PH steel using wire powder delivery, characterized in that: the method is used for laser additive manufacturing of 17-4PH steel components or on-site repair of damaged 17-4PH steel parts.

[0027] Beneficial effects of the invention

[0028] This invention belongs to the field of laser additive manufacturing technology, and relates to an apparatus and method for laser-pulsed current coupled additive manufacturing of 17-4PH precipitation-hardening stainless steel using wire and powder co-feeding. Addressing two key technical challenges in the laser additive manufacturing of 17-4PH steel—residual δ-ferrite and insufficient precipitation of nano-copper-rich phases—this invention proposes an in-situ control of the molten pool chemical composition through co-feeding of wire and powder. Furthermore, it employs a dual-mode control strategy, applying different pulse current parameters during the laser deposition stage and the interlayer pause stage, to achieve synergistic optimization of solidification structure control and solid-state aging precipitation promotion. The in-situ control is achieved using a wire-powder co-feeding system. The ratio and Cu content are used to suppress the formation of δ-ferrite and increase the driving force for CRP precipitation. Low-frequency, high-amplitude pulsed current during the laser deposition stage is used to enhance electromagnetic stirring and electromigration effects, promoting the δ→γ transition. High-frequency, low-amplitude pulsed current during the interlayer pause stage is used to enhance Joule heating and non-thermal effects, promoting CRP precipitation. A pure solid-state aging window is created using an interlayer pause time management submodule. Closed-loop composition control is achieved using a real-time calculation and control system for the molten pool composition. This invention reduces the δ-ferrite content from 5-15% in traditional laser additive manufacturing to below 1%. The abundant analysis of nano-copper-rich phases enables the printed hardness to reach 400-450 HV (approaching or reaching the H900 level of forgings), achieving excellent mechanical properties without post-heat treatment. Furthermore, the performance gradient of different regions of the component can be differentiated through the ternary synergistic control of composition, current, and pause. Attached Figure Description

[0029] Figure 1 A schematic diagram of a device for additive manufacturing of 17-4PH steel using a laser-pulse current coupling method that delivers both wire and powder.

[0030] In the diagram, 1 is a fiber laser, 2 is a laser transmission fiber, 3 is a laser processing head, 4 is a coaxial powder feeding mechanism, 5 is a coaxial wire feeding mechanism, 6 is a powder feeder (including multiple hoppers), 7 is a wire feeder, 8 is a dual-mode pulse power supply, 10 is a conductive fixture, 11 is a six-axis robot, 12 is a positioner, 13 is a gas flow meter, 14 is an argon cylinder, and 15 is a control terminal.

[0031] Figure 2 This is a detailed view of a part of the device.

[0032] In the figure, 9 is the electrode device (including insulating support 91, elastic clamping mechanism 92, and rolling electrode 93), 16 is the solidified deposit layer, and 17 is the molten pool.

[0033] Figure 3 Flowchart of the operation for laser-pulse current coupled additive manufacturing of 17-4PH steel using wire-powder co-feeding. Detailed Implementation

[0034] The present invention will be further described below with reference to the accompanying drawings and embodiments, but the present invention is not limited to the following embodiments.

[0035] In this invention, a conductive substrate is used as the substrate, and its surface is fixed on a conductive fixture after being polished and cleaned. The fiber laser transmits the laser light into the laser processing head through a laser transmission fiber. The laser processing head is equipped with a coaxial powder feeding mechanism and a coaxial wire feeding mechanism, so that the 17-4PH stainless steel wire, high-Ni powder, high-Cr powder, and high-copper powder converge near the laser focus and enter the molten pool together.

[0036] During implementation, the pulsed power supply automatically switches its operating mode according to the laser's on / off status: when the laser is turned on, it switches to laser deposition mode, applying a peak current of 400-600A, a frequency of 50-150Hz, a pulse width of 2000-5000μs, and a duty cycle of [missing information]. A pulsed current is applied to enhance electromagnetic stirring and composition homogenization of the molten pool; when the laser is turned off and enters the interlayer pause stage, the system switches to interlayer pause mode, applying a peak current of 150-300A, a frequency of 500-1500Hz, a pulse width of 200-600μs, and a duty cycle of [missing information]. A pulsed current is applied to promote the precipitation of copper-rich nanophases in solid tissues.

[0037] Meanwhile, the real-time calculation and control system for the molten pool composition calculates the composition of the molten pool in real time based on the wire feeding speed and the powder feeding speed of each hopper. The ratio and Cu content are used to adjust the powder feeding rate of each silo through a feedback control algorithm, so as to keep it stable within the target range.

[0038] In a preferred embodiment, The ratio is controlled between 1.0 and 1.5, and the Cu content is controlled between 4.5 wt% and 8.0 wt%. Within this range, the formation of excessive δ-ferrite can be suppressed, and the driving force for the formation of copper-rich precipitates can be increased.

[0039] In a preferred embodiment, the interlayer pause time is set to 0-300s, preferably 10-660s. This pause window provides the necessary time for interlayer solid-state aging, thereby improving the hardness and uniformity of the printed state.

[0040] In one embodiment, it can be used for direct additive manufacturing of large, complex components made of 17-4PH steel; in another embodiment, it can be used for in-situ repair of damaged 17-4PH steel components. For graded performance components, the deposition height can be adjusted. The ratio, Cu content, and interlayer dwell time are used to achieve hardness gradient variation and performance zoning design.

Claims

1. An apparatus for co-feeding wire and powder in laser-pulse current coupled additive manufacturing of 17-4PH steel, characterized in that, Includes: a laser thermal source system, comprising a fiber laser, a laser transmission fiber, and a laser processing head; the laser processing head employs a reflective optical design; A wire-powder co-feeding system includes a coaxial powder feeding mechanism, a coaxial wire feeding mechanism, and a multi-hopper powder feeder. The multi-hopper powder feeder includes at least three independently controlled hoppers, respectively filled with high-Ni powder, high-Cr powder, and high-copper powder. The coaxial wire feeding mechanism conveys 17-4PH stainless steel wire. A pulse current generation and application system includes a pulse power supply, a rolling electrode device, and a conductive clamp. The pulse power supply has two preset parameter modes: laser deposition mode and interlayer pause mode, and can automatically switch between the two modes according to the laser switching signal. The positive terminal of the pulse power supply is electrically connected to one end of the rolling electrode or the conductive clamp via a switching switch. The switching switch is controlled by a control terminal and automatically connects the positive terminal to the rolling electrode (laser deposition mode) or to the conductive clamp (interlayer pause mode) according to the laser's switching state. The negative terminal of the pulse power supply is always electrically connected to the other end of the conductive clamp. The rolling electrode is used to assist in conductivity and guide the filament, enabling current to be conducted to the molten pool area. The data acquisition and monitoring system includes a laser status module, a filament powder feeding monitoring module, and an interlayer pause timing module. The laser status monitoring module acquires the laser's on / off status signal in real time. The filament powder feeding monitoring module can monitor and adjust the feeding rate in real time. The motion and control system includes a six-axis robot and a positioner. The interlayer pause timing module starts timing after the laser is turned off, allowing the next layer deposition to begin after a preset pause time is reached. The inert gas protection system includes an argon cylinder and a gas flow meter. Each system is controlled by a control terminal, which adjusts based on monitoring information.

2. The apparatus for co-feeding wire and powder, laser-pulse current coupled additive manufacturing of 17-4PH steel according to claim 1, characterized in that: The pulse current parameters for the laser deposition mode are: peak current 400-600A, frequency 50-150Hz, pulse width 2000-5000μs, and duty cycle. The pulse current parameters for the interlayer pause mode are: peak current 150-300A, frequency 500-1500Hz, pulse width 200-600μs, and duty cycle. .

3. The apparatus for co-feeding wire and powder, laser-pulse current coupled additive manufacturing of 17-4PH steel according to claim 1, characterized in that: The high-Ni powder is pure Ni powder or Ni-based alloy powder, with a Ni content of... The high-Cr powder is pure Cr powder or Cr-based alloy powder, with a Cr content of... The high-copper powder is pure Cu powder or Cu-based alloy powder, with a Cu content of... .

4. The apparatus for co-feeding wire and powder, laser-pulse current coupled additive manufacturing of 17-4PH steel according to claim 1, characterized in that: The coaxial powder feeding mechanism and the coaxial wire feeding mechanism are integrated into the laser processing head to achieve coaxial convergence of the wire and multi-element powder at the laser molten pool.

5. A method for additive manufacturing of 17-4PH steel components using the apparatus according to any one of claims 1 to 4, characterized in that, Includes the following steps: S1. Substrate pretreatment: Grind the substrate / repair surface to remove the oxide layer, clean it with acetone or alcohol, and then fix the substrate on the conductive fixture; S2. Wire and Powder Co-feeding: The coaxial wire feeding mechanism is activated to transport 17-4PH stainless steel wire, and the multi-hopper powder feeder is activated at the same time to independently control the powder feeding amount of high Ni powder, high Cr powder and high Cu powder according to the target composition; S3. Laser Deposition and Pulse Current Application: The laser is turned on, the laser status monitoring module detects the laser turn-on signal, the pulse power supply is switched to laser deposition mode, and a specific pulse current is applied to the molten pool during the deposition process; S4. Interlayer pause processing: When one layer of deposition is completed, the laser status monitoring module detects the laser shutdown signal, the pulse power supply switches to interlayer pause mode, and starts the interlayer pause timer. The pause time is preset to 0-300s. During the interlayer pause, a high-frequency pulse current is applied for online aging processing. S5. Repeat steps S3 to S4 until the component is formed.

6. The method for additive manufacturing of 17-4PH steel components according to claim 5, characterized in that: In step S2, the chromium equivalent / nickel equivalent in the molten pool is controlled by adjusting the feeding ratio of high-Ni powder to high-Cr powder. The ratio is in the range of 1.1 to 1.5; the Cu content is controlled by adjusting the feed rate of the high Cu powder. to Within the range.

7. An additive manufacturing method for a 17-4PH steel graded performance component, implemented based on the apparatus described in any one of claims 1 to 4, characterized in that, include: A gradient composition distribution is designed along the deposition height direction of the component, and adjusted by... The ratio, Cu content, and interlaminar dwell time cause the hardness of the component to increase in a continuous gradient from bottom to top. The bottom region achieves higher toughness through a higher Creq / Nieq (1.4-1.5) and a lower Cu content (4.5-5.0 wt%), while the top region achieves high hardness through a lower Creq / Nieq (1.1-1.2) and a higher Cu content (5.5-6.5 wt%) combined with a longer interlaminar dwell time, thereby achieving a customized distribution of performance in different parts of the component.

8. A method for on-site repair of 17-4PH steel components, implemented based on the apparatus described in any one of claims 1 to 4, characterized in that, Includes the following steps: Clean and pre-treat the surface of the damaged 17-4PH steel components; Set the target component for repair: The ratio is 1.1-1.3, and the Cu content is... The repair layer was deposited using laser deposition and interlayer pause mode, with the interlayer pause time set to [value missing]. After repair, the interfacial shear strength with the matrix is ​​obtained. ,hardness Repair layer.

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