Applications of Energy Field Assisted Laser Shock Peening in Aerospace Components

With the rapid advancement of modern aviation technology, critical load-bearing components are subjected to complex service environments involving cyclic loading, high-temperature oxidation, and severe vibrations. These harsh conditions often lead to fatigue cracking, stress corrosion cracking, and high-temperature creep failures, posing serious threats to the safety and reliability of aerospace equipment. Laser shock peening can introduce deep residual compressive stresses into the surface layer of materials, significantly enhancing fatigue performance and corrosion resistance, and has been successfully applied to components such as engine blades and landing gears. However, conventional single-process laser shock peening technology faces limitations in terms of plastic deformation depth, microstructural control, and uniform strengthening of complex geometries. In recent years, energy field assisted laser shock peening has emerged by incorporating auxiliary energy fields such as ultrasonic vibration, electric pulses, magnetic fields, thermal fields, and cryogenic environments. This approach enables deeper energy coupling and precise multiscale microstructural regulation, significantly improving fatigue life, corrosion resistance, and high-temperature service performance of materials. This paper reviews the mechanisms and current applications of energy field assisted laser shock peening in aerospace components, focusing on the effects of different auxiliary fields on microstructural evolution, residual stress distribution, and mechanical property enhancement. Case studies on aerospace blades, turbine disks, and landing gears are presented to highlight its advantages in improving fatigue resistance, corrosion resistance, and structural reliability. Finally, future trends and potential applications of energy field assisted laser shock peening in intelligent manufacturing and surface strengthening of high-performance aerospace materials are discussed, providing theoretical guidance and engineering references for optimizing the comprehensive performance of critical aerospace components.

SiC particle-reinforced aluminum matrix composites (SiC_p/Al) demonstrate broad application prospects in lightweight and large-scale aerospace equipments due to their high specific strength, low density, and low coefficient of thermal expansion. However, defects such as the formation of the brittle Al₄C₃ phase, porosity, and particle segregation readily occur during their fusion welding, severely restricting their engineering applications. Consequently, the demand for high-efficiency and reliable welding techniques is becoming increasingly urgent. This paper systematically reviews the research status of laser welding for aerospace SiC_p/Al from three aspects: conventional laser welding, external-fieldassisted laser welding, and laser welding with interlayers. Conventional laser welding (continuous, pulsed, or wobbling) can only optimize joint performance through process regulation, but cannot effectively suppress the formation of the brittle phase, and the process window remains narrow. External energy field assistance (arc, magnetic field, or ultrasonic) laser welding can effectively stabilize the molten pool, reduce macroscopic defects, and refine grains, yet it struggles to block the interfacial reaction. Interfacial reaction regulation laser welding, by introducing active elements to reconstruct the interfacial reaction path and transforming harmful phases into strengthening phases, has emerged as the key to achieving performance leaps. Finally, this review discusses the future research hotspots of the laser welding for SiC_p/Al composites, aiming to provide a reference for the large-scale and reliable welding of this material in the aerospace field.

Laser welding has been widely used in aerospace automotive and other fields due to its advantages of high weld seam quality, high processing efficiency, and low heat-affected zone. During the welding process, fluctuations on the surface of the molten pool directly affect the quality of the weld formation, making it significant to investigate the flow behavior of the shallow melt. In this study, a small amount of aluminum oxide (Al₂O₃) particles was introduced as tracers during welding. By combining image processing and machine learning methods, the motion trajectories of surface oxides in the molten pool were extracted and analyzed, quantifying the changes in surface melt flow velocity at different penetration stages. By correlating features such as temperature, spatter, and molten pool spot frequency, the periodic variation patterns of vortices on both sides of the molten pool surface during complete penetration stage were revealed, and their respective correlations with spatter behavior and keyhole breakthrough phenomena were illustrated. This study provides valuable references for analyzing the surface flow of shallow molten pools and optimizing weld surface quality.

In this paper, the detection methods and evaluation systems for material surface cleanliness after laser cleaning are systematically reviewed. These encompass various online detection techniques such as laser-induced breakdown spectroscopy (LIBS), fluorescence spectroscopy, reflectance spectroscopy, acoustic signal analysis, and image recognition, as well as offline methods like wettability testing, surface morphology observation, and elemental analysis. The research finds that these diverse methods can effectively identify the characteristic stages of insufficient cleaning, complete cleaning, and excessive cleaning during the cleaning process, with distinct signal features reflecting the evolution of the cleaning state. The collaborative analysis of multi-source detection information aids in enhancing the accuracy of state recognition and process monitoring. At present, there are differences among these methods in terms of response mechanisms, evaluation dimensions, and application scopes. Techniques such as LIBS, spectroscopy, and acoustic signal analysis are more suited for laboratory conditions, whereas image acquisition and analysis, as well as roughness and wettability assessments, are more practical for on-site industrial monitoring. Each detection method yields distinct results with its own characteristics. Future research can further explore areas such as multi-modal integration, cross-scale modeling, and the establishment of standardized systems, thereby advancing laser cleaning quality detection towards higher precision, intelligence, and engineering applicability. This progression will help meet the technical demands for surface cleanliness control in aerospace manufacturing and other advanced industrial fields.

With the rapid advancement of aerospace technology, difficult-to-machine materials such as high-strength alloys, ceramics, and composites have gained widespread application. But traditional machining methods struggle to meet the demands for high-quality processing. Waterjet-guided laser processing technology, with its advantages of high precision and low damage, addresses the shortcomings of tool wear and large heat-affected zones inherent in conventional mechanical machining and laser machining, demonstrating significant application potential. Therefore, this paper systematically reviews the working mechanisms and practical applications of waterjet-guided laser processing technology for difficult-to-machine materials in the aerospace field. First, it elaborates on the fundamental principles of waterjet-guided laser processing, the multi-field coupling material removal mechanism, and comprehensively introduces the core components of the waterjetguided processing system. Second, it delves into its multidimensional working mechanisms from three dimensions: water jet characteristics, optical properties, and water-optical coupling characteristics. Subsequently, it comprehensively summarizes research progress in cutting and hole-making processes for “difficult-to-machine materials” using waterjetguided laser technology. Finally, it explores typical application scenarios of this technology in precision machining, based on current research status, and outlines future development trends for waterjet-guided laser precision machining technology.

Laser – CMT (cold metal transfer) hybrid welding can increase penetration depth, enhance efficiency, and improve weld formation, yet the laser power is crucial for weld formation and process stability. In this study, high-speed imaging and electrical signal method were employed to investigate the weld formation and process stability during laser–CMT hybrid welding of a 6 mm medium-thick aerospace ultra-high-strength steel plate. The results show that the addition of laser shortens the droplet short-circuiting process, prolongs the boost and waiting times, and the droplet diameter slightly increases with laser power, yet the transition frequency remains essentially unchanged at 97 Hz. As laser power increases, the frequency of current instability increases, affecting the stability of the welding process. Analysis indicates that during the detachment and boost phases, the impact force of the droplet and the arc pressure impact and squeeze the keyhole, which is the main cause of keyhole instability. When the laser power is at 5000 W, the keyhole is fully penetrated, and the metal vapor force maintaining keyhole stability maintains a dynamic balance with the droplet impact force and arc pressure, resulting in the best formation with a porosity rate only 0.14%. However, when the power is increased or decreased, the formation deteriorates and porosity defects increase.

Reaction-bonded silicon carbide (RB-SiC) ceramics are critically important for applications in space optics and precision manufacturing due to their excellent thermophysical properties and near-net-shape capability. However, their high hardness, brittleness, and multi-phase composite structure (consisting of multi-sized SiC grains and free silicon) classify them as typical difficult-to-machine materials. To address the specific structure of RB-SiC, this study proposes a femtosecond laser selective processing strategy. By switching between a galvanometer-objective lens system (with a spot diameter of 4 μm) and a galvanometer-field lens system (with a spot diameter of 28 μm), selective microtexturing and high-efficiency planarization of RB-SiC are achieved, respectively. Experimental results indicate that under low energy density, the objective lens system enables the selective removal of free Si and submicron SiC particles while preserving the large SiC skeleton structure on the scale of tens of micrometers. Conversely, under high energy density, the field lens system produces smooth microgrooves with a surface roughness Ra < 1.5 μm and a removal depth >270 μm. The combination of these two processing methods facilitates the creation of functional micro-structured surfaces. By integrating dual-temperature model simulations with multiple characterization techniques, the interaction mechanism between laser parameters and the material's multi-phase structure was systematically elucidated, clarifying the physical principles underlying selective material removal. This work provides new insights and key technical support for the laser-based precision machining of multi-phase composite materials.

Inconel 718 pre-alloyed powder was prepared by electrode induction melting gas atomization (EIGA). Powder metallurgy (PM) Inconel 718 alloy was formed by hot isostatic pressing (HIP) + special high temperature heat treatment (SHT) and then its microstructure was observed and its mechanical properties were tested. The results show that the SHT can reduce prior particle boundaries (PPBs) and improve the elongation and impact toughness of PM Inconel 718 alloy. Based on the SHT, the holding time of the high-temperature section is extended and the HIP is optimized. The optimized process can inhibit or eliminate PPBs in PM Inconel 718 alloy, increase the number of twins, and improve the alloy properties. The tensile elongation at 650 ℃ has been increased from 6% to 10%. The optimized HIP can be used as an alternative process to HIP + SHT to achieve near-net-shape and achieve the purpose of cost reduction and efficiency increase.

High-power fiber lasers are critical in advanced manufacturing and defense applications, yet their high-power output poses severe thermal management challenges that limit long-term stability and further development. Traditional cooling methods suffer from inefficiency and system complexity. This study proposes an immersed phasechange cooling system utilizing the latent heat of the low-boiling-point working fluid R245fa for efficient heat dissipation. By integrating numerical simulations with experimental validation, the thermodynamic characteristics and structural design were analyzed, leading to an optimized integrated packaging solution. Simulation results demonstrated a temperature rise of only 8 ℃ within 100 s, maintaining stability within the safe operating range of laser components. Experimental tests on an engineering prototype confirmed the system’s effectiveness, achieving a total heat dissipation capacity of 25 kW. The proposed system significantly improves thermal efficiency and reliability while reducing energy consumption and system volume, offering an innovative solution for advancing high-power laser technology and broadening its applications with substantial engineering value.

Based on orthogonal tests, the optimization method of binder jetting forming Ti6Al4V alloy process was investigated, and the powder gradient optimization strategy was proposed, revealing the control mechanism of fine powder introduction on the pore structure and forming performance of the samples. The influence of printing process parameters on the forming properties of green part is investigated by orthogonal test, and the correlation relationship between the properties of green part is constructed based on the normalization analysis method to obtain the optimal process parameters, and the particle size distribution is further regulated by the strategy of coarse and fine powder gradient to investigate the influence of fine powder content on the properties of green part and sintered parts. The results show that the layer thickness has the most significant effect on the properties, followed by the inkjet density, and the rotational speed has a higher effect on the properties of the green part than the horizontal speed. The optimum process parameters were 100 μm layer thickness, 85% inkjet density, 100 mm/s horizontal speed and 2.0 r/s rotational speed. When the mass fraction of fine powder is 10%, the green part performance was optimal, with a relative density of 52.22% and a compressive strength of 3.27 MPa. When the mass fraction of fine powder is 20%, the sintered parts achieve the optimal mechanical properties, with a compressive strength of 642.94 MPa and a Vickers hardness of 420.68HV. When the mass fraction of fine powder is increased to 30%, the relative density of the sintered body reaches 93.11%. This provides a reference for the optimization of binder jetting forming process parameters and the regulation of sample properties of Ti6Al4V alloy.

Aluminum alloys are extensively utilized in critical aerospace structural components, where surface conditions directly impact fatigue life and structural reliability. To investigate the fatigue strength enhancement of typical structures through laser shock peening (LSP) and mechanical shot peening (MSP), notched specimens of 7050 and 2024 aluminum alloys were prepared. The effects of LSP and MSP on residual stress fields and surface hardness were systematically examined, with subsequent analysis of changes in the detail fatigue strength cutoff (DFR_cutoff). Key findings include: MSP demonstrated superior amplitude and uniformity in surface compressive residual stress for both alloys compared to LSP, though with significantly shallower affected depths; LSP induced pronounced surface hardening, while MSP provided limited hardness improvement. LSP elevated DFRcutoff of 2024 and 7050 aluminum alloys by 21.9% (163.7 MPa) and 48.1% (175.0 MPa), respectively, substantially exceeding MSP-treated specimens. For notched structures, LSP generated deeper compressive residual stress layers and higher microhardness, effectively delaying fatigue crack initiation/propagation at stress concentration zones and enhancing fatigue resistance.