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Enhancement of weld strength of laser-welded joints of AA6061-T6 and TZM alloys via novel dual-laser warm laser shock peening
摘要： In this paper, an experimental study is presented on an investigation to improve the weld strength of laser-welded joints via post-processing by warm laser shock peening (wLSP). A dual-laser setup was utilized to simultaneously heat the sample to a prescribed temperature and to perform the wLSP process on the laser-welded joints of AA6061-T6 and TZM alloys. Joints in overlap and bead-on-plate configurations were created by laser welding by a high-power fiber laser and post-processed with wLSP. The tensile tests carried out on wLSP-processed AA6061-T6 samples demonstrate an enhancement in the strength by about 20% over as-welded samples and the ductility of samples processed by wLSP improved by 30% over as-welded samples. The bead-on-plate (BOP) welds of TZM alloy processed with wLSP demonstrated an enhancement in strength by about 30% and the lap welds processed with wLSP demonstrated an increase in the joint strength by 22%. Finite element analysis revealed that the depth and magnitude of compressive stresses imparted by wLSP were greater than room temperature laser shock peening (rtLSP), which contributed to the enhancement of the joint strength for processed samples.
关键词： Al6061,Warm laser shock peening,Strength improvement,Laser welding,TZM
更新于2025-11-28 14:24:20
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Effects of coverage layer on the electrochemical corrosion behaviour of Mg-Al-Mn alloy subjected to massive laser shock peening treatment
摘要： Effects of coverage layer on electrochemical corrosion behaviour and pitting morphologies of Mg-Al-Mn alloy subjected to massive laser shock peening (LSP) treatment were investigated by potentiodynamic polarisation test, electrochemical impedance spectroscopy (EIS), and scanning electron microscope (SEM) observations. Microstructures of Mg-Al-Mn alloy subjected to massive LSP treatment were also characterized. Results showed that LSP induced an obvious improvement in electrochemical corrosion resistance with increasing coverage layer. Even in a higher corrosive solution concentration, LSP could still prevent corrosion to some extent. The improvement in electrochemical corrosion resistance was due to the grain refinement and compressive residual stress induced by massive LSP treatment. Finally, the influence mechanism of the coverage layer on electrochemical corrosion behavior of Mg-Al-Mn alloy was revealed.
关键词： Microstructure.,Electrochemical corrosion,Mg-Al-Mn alloy,Coverage layer,Laser shock peening
更新于2025-09-23 15:23:52
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Investigation the effect of laser ablation parameters in a liquid in order to reduce the pulse energy during laser shock peening
摘要： The features of laser shock peening technology was studied in relation to the physical processes occurring during and after laser treatment. The effect of laser parameters on the results of the process was investigated. It was shown that the reduce of the diameter of the laser spot while maintaining the intensity leads to a decrease in the effect of LSP. This phenomenon was studied from the point of view of the features of plastic deformation at various sizes of the treatment zone using the standard model for the LSP process. Besides the features of the development of a plasma plume during laser ablation in a liquid are considered. It was shown that the liquid determines the geometry of the plume evolution and the shock wave caused by it. The process parameters used and the results obtained are important for the development of low-energy LSP technology.
关键词： Surface treatment,Laser shock peening,Laser-produced plasmas,Laser ablation in liquid,Nickel alloys,Laser pulses,Lasers
更新于2025-09-23 15:21:01
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Gradient microstructure and vibration fatigue properties of 2024-T351 aluminium alloy treated by laser shock peening
摘要： To investigate the improvement in vibration fatigue and the strengthening mechanism of laser shock peening, a nanosecond laser was used to strengthen the 2024-T351 aluminium alloy. Accordingly, the microstructure, residual stress, nanohardness and surface roughness of the treated alloy were measured. Subsequently, the vibration fatigue damage and fatigue life were evaluated, and the vibration fracture morphology was observed. The results showed that the grains in the peened surface were re?ned. A residual stress of ?141 MPa and a nanohardness of 3.1 GPa were obtained by laser shock peening. Based on the relationship between the peened microstructure and fracture morphology, it was deduced that an increase in the grain boundaries led to a lower crack initiation rate and a higher crack initiation life. The compressive residual stress decreased the crack growth rate and increased the crack growth life. Therefore, laser shock peening increases the total vibration fatigue life by about 63.5%.
关键词： Laser shock peening,Vibration fatigue,2024-T351 aluminium,Compressive residual stress,Microstructure
更新于2025-09-23 15:21:01
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Taguchi Grey Relationalapproach Foroptimizing Process Parameters of Laser Peeningontitanium Alloy to Induce Enhanced Compressive Stress Based on Finite Element Simulation
摘要： Laser Shock Peening (LSP) turned out the most efficient surface engineering process for advanced materials to induce beneficial deep compressive residual stress which helps in improving mechanical, fatigue properties and surface damage resistance. But, analyzing the non-uniform distribution of residual stresses in the treated sample with XRD is much time taking and costly process. This problem can be resolved with LSP finite element numerical simulation model which is feasible with the realistic experimental process. The FE model allows the user to control the laser parameters in order to achieve the optimal level of all controllable parameters. The present study is intended to analyze and optimize the influence of laser processing parameters assists in inducing the residual compressive stress with minimal surface deformation.A Ti6Al4V material model with Johnson-Cook’s visco-elastic-plastic material behaviour law is prepared for LSP simulation. And Gaussian pressure profile is utilized for uniform loading of the targeted zone for the proposed model. Taguchi Grey Relational Analysis (TGRA) with L27 orthogonal array is applied to LSP simulation, and the results were analyzed with consideration of multiple response measures. It is noted that surface deformation is increased with the rise in a number of laser shots and pressure pulse duration. Maximum compressive residual stresses are falling for higher levels of laser spot diameter, Laser spot overlap and Laser Power density. The correlation is observed between FE simulation and published results. The optimal set of process parameters are obtained for improving the LSP on Ti alloys.
关键词： Grey Relational Analysis (GRA),Taguchi Technique,Laser Shock Peening (LSP),Finite Element Method (FEM),Residual Stresses
更新于2025-09-23 15:21:01
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Fatigue behaviors of foreign object damaged Ti-6Al-4V alloys under laser shock peening
摘要： Two-sided and simultaneous laser shock peening (TSLSP) was used to strengthen the Ti-6Al-4V titanium alloy. The fatigue crack growth rate of the specimens was investigated by fatigue test. The results show that both direct TSLSP (TSLSP-D) and indirect TSLSP (TSLSP-I) can reduce the fatigue crack growth rate by producing high magnitude compressive residual stress. The maximum fatigue life increases by 94% (TSLSP-D) and 169% (TSLSP-I) compared with the original specimens. Moreover, the TSLSP-D results show decreased resistance to foreign object damage because of decreased plasticity while the TSLSP-I simultaneously achieves superior foreign object damage resistance and fatigue performance.
关键词： Fatigue performance,Foreign object damage,Two-sided and simultaneous laser shock peening,Titanium alloy
更新于2025-09-23 15:21:01
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[Laser Institute of America ICALEO? 2015: 34th International Congress on Laser Materials Processing, Laser Microprocessing and Nanomanufacturing - Atlanta, Georgia, USA (October 18–22, 2015)] International Congress on Applications of Lasers & Electro-Optics - Microstructural effects induced by laser shock peening for mitigation of stress corrosion cracking
摘要： Stress corrosion cracking is a phenomenon that can lead to rapid, sudden failure of metallic products. In this paper we examine the mechanisms of SCC mitigation of stainless steel and brass samples using laser shock peening (LSP). The behavior of hydrogen within the crystal lattice is one of the most dominant contributors to SCC, where uptake of hydrogen strains the lattice and increases its hardness. Cathodic charging of the metallic samples in 1M sulfuric acid was performed in order to accelerate hydrogen uptake. Non-treated samples underwent hardness increases of 28%, but LSP treated samples only increased in the range of 0 to 8%, indicative that LSP keeps hydrogen from permeating into the metal. Mechanical U-bends subjected and MgCl2 environments are analyzed, to determine changes in fracture morphology. Surface chemical effects are addressed via Kelvin Probe Force Microscopy, which is used for finding changes in the work function caused by LSP treatment. A finite element model of material deformation from U-bending was developed to analyze and compare the induced stresses. With LSP, there is a potential for overprocessing the samples, whereby negative effects refinement, to corrosion martensite formation) can arise. Detection of any martensite phases formed is performed using x-ray diffraction. We find LSP to be beneficial for stainless steel but does not improve brass’s SCC resistance. With our analysis methods we provide a further understanding of the process whereby LSP reduces subsequently highlight SCC for important implementation of the process.
关键词： Brass,Stainless steel,Hydrogen uptake,Stress corrosion cracking,Cathodic charging,Kelvin Probe Force Microscopy,Laser shock peening,Finite element model
更新于2025-09-23 15:21:01
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On the application of laser shock peening for retardation of surface fatigue cracks in laser beam-welded AA6056
摘要： The present study aims to investigate the extent to which the fatigue behaviour of laser beam-welded AA6056-T6 butt joints with an already existing crack can be improved through the application of laser shock peening. Ultrasonic testing was utilized for in situ (nondestructive) measurement of fatigue crack growth during the fatigue test. This procedure allowed the preparation of welded specimens with surface fatigue cracks with a depth of approximately 1.2 mm. The precracked specimens showed a 20% reduction in the fatigue limit compared with specimens without cracks in the as-welded condition. Through the application of laser shock peening on the surfaces of the precracked specimens, it was possible to recover the fatigue life to the level of the specimens tested in the as-welded condition. The results of this study show that laser shock peening is a very promising technique to recover the fatigue life of welded joints with surface cracks, which can be detected by nondestructive testing.
关键词： fatigue crack,aluminium alloys,laser beam welding,ultrasonic crack tip diffraction,residual stress,laser shock peening
更新于2025-09-23 15:19:57
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Effect of laser shock peening on mechanical and microstructural aspects of 6061-T6 aluminum alloy
摘要： Laser shock peening (LSP) of 6061-T6 aluminum alloy was performed and parametric effects post LSP on mechanical aspects and microstructural evolution are meticulously studied using various means of characterization techniques such as residual stress analysis, surface roughness, Vickers microhardness, tensile testing, X-ray diffraction (XRD) analysis, transmission electron microscopy (TEM) and electron back scattered diffraction (EBSD). Work hardened layer of ~1500 μm depth is obtained with significant improvement in cross-sectional microhardness up to 33.04%. Beneficial compressive residual stress of maximum magnitude up to -273 MPa was induced in laser peened specimens concentrating its overall effect around the depth of 100 μm along the effective depth region. Second phase Mg5Si6 (β?) precipitates were observed post LSP while analyzing XRD profiles along with the peak broadening and peak shifting towards higher 2θ angle justifying the results obtained in microhardness profile. High angle grain boundaries (HAGBs) fraction was increased in LSPed specimens and its effect is noticed in residual stress profile. Mg5Si6 (β?) precipitates are attributed as contributing precipitates in improving the mechanical properties of LSPed specimens along with the dense dislocation density caused by severe plastic deformation during LSP. The collective contribution of strain hardening, second phase precipitates, peak broadening, dislocation density and increased fraction of HAGBs is observed in mechanical and microstructural aspects of LSPed specimens. The results are discussed in detailed and are strongly correlated with each other.
关键词： EBSD,Aluminum alloy,cosα method,TEM,XRD,Laser shock peening
更新于2025-09-23 15:19:57
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Effects of laser shock peening on microstructure and fatigue behavior of Tia??6Ala??4V alloy fabricated via electron beam melting
摘要： Laser shock peening (LSP) is a post-treatment process that is widely used to modify the surface microstructure and mechanical properties of parts constructed by additive manufacturing (AM). In this study, the influence of LSP on the microstructure and fatigue behavior of Ti–6Al–4V alloy manufactured via electron beam melting (EBM), a popular method of AM, was investigated. The microstructure of the EBM sample consisted of the β phase (~6 vol%) and α lamellar phase. Grain refinement of the α phase occurred via both dislocation evolution and deformation twinning during LSP. A theoretical description of the microstructural evolution, particularly the distribution of deformation twins, was developed. The fatigue strength and micro-hardness of the EBM samples increased by approximately 17% and 11% after LSP treatment, respectively. The fatigue fracture morphologies at three defined damage stages (crack initiation, crack propagation, and instantaneous rupture) were examined for EBM samples before and after LSP. The dominant mechanism of fatigue strength enhancement by LSP was discussed. The effects of residual compressive stress assistant with adiabatic temperature increase and grain refinement of the α phase produced by LSP reduced the pre-existing crack size, suppressed crack initiation, and increased the required work for fatigue fracture.
关键词： Laser shock peening,Electron beam melting,Ti–6Al–4V titanium alloy,Fatigue behavior,Microstructural characterization
更新于2025-09-23 15:19:57