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Influence of multiple laser peening on vibration fatigue properties of TC6 titanium alloy
摘要： In this study, typical TC6 titanium alloy was taken to investigate the effects of multiple laser peening (LP) on the vibration fatigue properties and microstructural evolution. The vibration fatigue experiments were conducted, while the vibration fatigue life of the specimens before and after LP was compared and the fracture morphologies were observed by scanning electron microscopy (SEM). In addition, the measurements of residual stress and microhardness were carried out. The microstructures produced by different treatments were also characterized by transmission electron microscopy (TEM) and electron backscattered diffraction (EBSD). The experimental results indicated that multiple LP could indeed enhance the vibration fatigue properties of TC6 titanium alloy. Comparing with the investigated specimen without LP, the vibration fatigue life of the specimen subjected to 5 times LP increased by 105.2%. Meanwhile, after 5 times LP, the surface residual stress transformed from tensile stress (+26 MPa) to compressive stress (?485 MPa), and the surface microhardness was 428 HV, which increased by 32.9% compared with the untreated sample. Additionally, high-density of dislocation and deformation twin were also generated after multiple LP. The improvement of vibration fatigue properties was attributed to the rewarding compressive residual stress and the beneficial microstructural evolution induced by multiple LP.
关键词： TC6 titanium alloy,Laser peening,Vibration fatigue properties,Microstructure evolution,Residual stress
更新于2025-11-14 17:04:02
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The effects of laser peening on laser additive manufactured 316L steel
摘要： Laser peening has an extensive application in traditional manufacturing industry. However, in additive manufacturing, the initial stresses on the parts often reduce the effects of laser peening and make it hard to achieve a desirable residual stress distribution. In this investigation, the interaction of initial residual stress and laser peening-induced stress was studied through numerical simulation and experimental tests. A finite element model (FEM) model was built to predict the stress distribution on laser-deposited sample, and its changed state is affected by laser peening. The microstructure and mechanical properties were also characterized experimentally. The result turned out that the thermal-induced tensile residual stress in laser-deposited sample can affect the laser peening result in both horizontal and longitudinal directions. Some mechanical properties of the LAMed sample were changed after LSP treatment. The hardness on the surface and 1-mm depth have been increased by 7% and 22%, respectively, and the yield strength was increased by 16%, while there is no significant change in the tensile strength and elongation rate.
关键词： Finite element analysis,Laser peening,Laser additive manufacturing,Residual stress
更新于2025-09-23 15:21:01
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Grain orientation and crystallographic texture governed gradient oxidation in laser peening
摘要： This study examined the microstructural/crystallographic textural changes within a laser peened circular spot on Al-Li alloy 2060-T8 and their correlation with gradient oxidation. These changes were looked at the center and edge regions of the circular spot peened at 8 J and 13 J pulse energies. At the pulse energy of 13 J, grain orientation profoundly changed from h0 0 1i (base region) to h1 1 0i (laser spot) with reduced low coincidence site lattice boundaries at the edge of the laser spot. Ideal fibre texture was transformed into strong Cube {0 0 1} h1 0 0i and Goss {0 1 1} h1 0 0i textures respectively at 8 J and 13 J. Dense atomic structured h1 1 0i and h1 1 1i grain orientations and transformed strong Goss texture are observed to promote the oxidation significantly at the edge of laser spot for 13 J. Reasons for gradient oxidation within the laser peened spot were explained from the view point of microstructural/crystallographic textural changes.
关键词： Al-Li alloy,Oxidation,Grain boundaries,Texture,Laser peening
更新于2025-09-23 15:19:57
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Strengthening mechanism of Nd: Yag laser shock peening for commercially pure titanium (CP-TI) on surface integrity and residual stresses
摘要： In the present work, an attempt has been made to investigate the effect of generating shock waves through direct and con?ned ablation modes of plasma method of massive laser shock peening (MLSP) on surface integrity of cast dumbbell shaped and cylindrical cast specimens of commercially pure titanium (CP-Ti) and to compare with those of untreated CP-Ti. The MLSP is usually performed in a massively peening mode to induce uniform compressive residual stress and surface deformation across the entire specimens. After MLSP, tensile testing was carried out to obtain the tensile strength, modulus of elasticity and percentage elongation. The microstructural and surface topography investigations of the laser shock peened material were carried out using digital, optical microscopy and SEM equipped with an energy dispersive spectrometer (EDS) and XRD. The results show that laser shock peened with con?ned ablation make the surface of CP-Ti with improved change in microstructure, increase in tensile strength, microhardness (73.08%), surface roughness and compressive residual stresses ((cid:1)420 MPa) which prolongs the mastication ability and dimensional stability of dental implant restorative materials.
关键词： Massive laser peening,Direct ablation mode,Con?ned ablation mode,Microstructure,Microhardness
更新于2025-09-19 17:13:59
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Test Results for Wrought and AM In718 Treated by Shot Peening and Laser Peening Plus Thermal Microstructure Engineering
摘要： Fatigue life improvement by shot peening (SP) and laser peening (LP) on metals is already well known. However, we are short of information about results on manufacturing (AM) parts, which are characterized by bad surface finishing, micro-porosities and structural defects. This paperstudies the effects of SP and LP on AM In718. Residual stress profiles, fractures surface, fatigue results will be detailed. Different thermal microstructure and surface preparations are compared: raw AM, SP, LP, polished.
关键词： Fatigue,Thermal,Shot Peening,Additive Manufacturing,Laser Peening
更新于2025-09-16 10:30:52
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Effects of laser peening on the fatigue strength and defect tolerance of aluminum alloy
摘要： The effects of laser peening (LP) on the bending fatigue strength of the 7075-T651 aluminum alloy were investigated. Accordingly, the defect tolerance of the aluminum alloy subjected to LP is discussed on the basis of fracture mechanics. The results indicate that a deeper compressive residual stress was induced by LP compared with the case of shot peening (SP). The fatigue strengths increased when both peening types were used. Semicircular slits with depths less than 0.4 and 0.1 mm were rendered harmless on the basis of the applications of LP and SP, respectively. The apparent threshold stress intensity factor range ΔKth,ap increased by approximately five and two times owing to LP and SP, respectively. The increase of the ΔKth,ap was caused by the compressive residual stress induced by the peening. The Kitagawa-Takahashi diagram of the laser-peened specimens shows that the defect tolerance of the aluminum alloy was improved by LP.
关键词： fatigue strength,laser peening,residual stress,shot peening,defect tolerance,aluminum alloy
更新于2025-09-16 10:30:52
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Femtosecond laser shock peening of galvanized stainless steel
摘要： In this paper a SUS316L stainless steel was electroplated with metallic layers and coated with polymer films. A sub-100fs ultrashort laser pulse with a central wavelength of λ=800nm was utilized to process the layer. The aim was to generate shock waves due to ablation of the deposited sacrificial layers. Generated shockwaves propagate and penetrate the lower stainless-steel sample and increase its mechanical hardness (Laser Shock Peening). The sacrificial layer protects the sample from ablation damage and determines the shock wave coupling. To achieve maximal peening, we compare different sacrificial layers and laser processing parameters.
关键词： Ultrashort Laser Peening,Shock hardening,LIPSS,Laser Shock Peening
更新于2025-09-12 10:27:22
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High energy femtosecond laser peening of 2024 aluminum alloy
摘要： A femtosecond laser with a pulse energy of up to 100 mJ is used to investigate the feasibility of laser peening of a 2024 aluminum alloy that is widely used in aerospace industry. Laser beam directly irradiates the as-received aluminum sample surface in air without any protective coating for laser absorption and transparent overlay for plasma confinement. The effects of pulse energy, pulse duration and beam spot size on peening performance are studied. Optical microscope and SEM are used to examine the surface morphology of laser peened samples. Vickers hardness test is used to determine the microhardness on the surface. Residual stresses on the surface and at selected depths are measured using x-ray diffraction method. It is found that femtosecond laser can impart compressive residual stresses to a depth of more than 100 μm for this material, but the surface stress condition is not altered significantly.
关键词： residual stress,aluminum alloy,hardness,femtosecond laser,surface texture,laser peening
更新于2025-09-12 10:27:22
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Maskless Patterning of Metal Outflow in Alternating Metal/Ceramic Multiple Nanolayers by Femtosecond Laser Irradiation
摘要： In this work, solid-state metal transport from internal metal nanolayers onto the surface of metal/ceramic nano-multi-layers (NMLs) has been directed in a controlled way by femtosecond (fs) laser irradiation and subsequent low temperature thermal annealing. Laser irradiation induced modifications of the NML microstructures and stress states can be limited within the first few top nanolayers due to the focused laser energy input at the metal/ceramic interface by exploiting the local plasmonic effect. Accompanied laser peening can further refine the crystallites and introduce compressive stress at the laser-irradiated region, which reduces the activation energies for vacancy formation and migration of metal atoms in the nano-confinement. Patterned Cu surface nanostructures (outflow) appear selectively along the laser path after air annealing at temperatures down to 360 ℃. For the solid-state diffusion of Cu in confinement, in-plane metal transport along the Cu-AlN interfaces is much faster than the outward short-circuit diffusion of Cu across the AlN barrier layers. Localized metal outflow is accompanied by the collapse and sintering of the remaining AlN barrier layers, under influence of the acting capillary forces, which may further accelerate the metal transport. This laser induced maskless patterning of metal outflow is not only applicable in Cu/AlN NMLs, but also in Ag/AlN NMLs, assisted by subsequent low temperature annealing.
关键词： solid-state metal transport,laser peening,metal/ceramic nanolayers,femtosecond laser,plasmonic effect
更新于2025-09-12 10:27:22
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Surface Micro patterning of Aluminium Reinforced Composite for Aerospace Applications through High Energy Pulse Laser Peening
摘要： Aluminium (Al) Composites have universal engineering applications because of their higher strength to weight ratio, ductility, and formability. However, in diverse applications, mechanical properties such as hardness, corrosion, wear, and fatigue resistance are the prerequisite at closer surface regions. Such localised changes without impacting various surface treatment approaches can attempt the bulk phase. Laser shock peening is an advanced surface engineering technique, which has been successfully applied to improve the surface morphology and microstructure of the material. In this work, we are focusing on improving the surface properties of Al7075 reinforced with SiC and Zirconia through laser peening technique. The hardened layer was evaluated using surface integrity with optical microscopy, energy dispersive spectroscopy, scanning electron microscope (SEM) and analysis of microhardness. Process parameters and resulting microstructures of Aluminium composite are summarised, along with the impact of laser peening on surface properties. Research results indicated that laser peening shows a significant influence on the final condition of the surface layer of Aluminium composite.
关键词： Zirconia,Aluminium Metal Matrix Composites,SiC,SEM,Laser peening
更新于2025-09-12 10:27:22